329 results on '"Gerrits T"'
Search Results
152. Picosecond coherent magnetisation reversal by magnetic field pulse shaping.
- Author
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Gerrits, T., van den Berg, H.A.M., Hohlfeld, J., Bar, L., and Rasing, T.
- Published
- 2002
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153. There's hope -- early observations of ARV treatment roll out in South Africa.
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Abah, S. J., Addo, E., Adjei, P. C., Arhin, P., Barami, A. A. S., Byarugaba, M. A., Chibuta, C. S., Chowdhury, A. K., Dlamini, L., Ekezie, C. C., Essobe, J., Gerrits, T., Gitau, L. N., Hadiyono, J. E. P., Irunde, H., Kafoa, B., Kekana, L., Kgatlwane, J., Kibria, G., and Kwasa, R.
- Abstract
The article discusses a study which examined the adherence to antiretroviral (ARV) drugs among people living with HIV/AIDS (PLWHA) in South Africa. Some of the factors affecting adherence to ARV treatment include perceived quality of care, privacy, respectful treatment, waiting time and information given to PLWHA. Some of the factors that complicate adherence to treatment include: costs of the treatment; food; family support; side-effects and PLWHA's knowledge and conflicting information.
- Published
- 2005
154. A near-infrared 64-pixel superconducting nanowire single photon detector array with integrated multiplexed readout
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Prochazka, Ivan, Sobolewski, Roman, James, Ralph B., Allman, M. S., Verma, V. B., Stevens, M., Gerrits, T., Horansky, R. D., Lita, A. E., Marsili, F., Beyer, A. D., Shaw, M. D., Kumor, D., Mirin, R., and Nam, S. W.
- Published
- 2015
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155. The Divine in the Clinic: Assisted Reproduction and Religious Practice in Ghana and South Africa.
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Whittaker A, Gerrits T, and Manderson L
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Drawing on studies with 40 informants in Ghana and 74 informants in South Africa, we explore spiritual interventions among staff and patients that accompany their use of assisted reproduction. These practices and expressions of faith reinforce staff and patients as moral subjects who have done everything possible to assist in the vagaries of assisted reproduction-another form of care to enable, complement, and enhance high-tech intervention. We consider the creation of sacred spaces in the clinics, the rituals that form part of IVF practice, and the dilemmas of translation when assisted reproductive technologies (ARTs) travel to different cultural and religious contexts., Competing Interests: Declarations. Conflicts of interest: We declare no conflicts of interest. Ethical approval: Ethical clearance was granted by Monash University (MUHREC 27166), University of the Witwatersrand, Johannesburg (M210546), and participating clinics. Ethical clearance for the Ghanaian Project was obtained through the Noguchi Memorial Institute for Medical Research-IRB in Accra, Ghana. Informed signed consent was obtained from all informants., (© 2025. The Author(s).)
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- 2025
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156. FERTILITY CARE IN LOW AND MIDDLE INCOME COUNTRIES: Embryologists' practices of care in IVF-clinics in sub-Saharan Africa.
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Gerrits T, Whittaker A, and Manderson L
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- Humans, Africa South of the Sahara, Female, Embryology, Developing Countries, Fertility Clinics, Male, South Africa, Counseling, Fertilization in Vitro
- Abstract
Abstract: Despite the centrality of the role of embryologists in in vitro fertilization (IVF), there is relatively little literature on the nature of their work. In this article, we draw on results from a large ethnographic study on the emerging IVF industry in South Africa and reproductive travel in sub-Saharan Africa (SSA), where IVF clinics and embryologists are scarce. Drawing on qualitative interviews with 11 embryologists, who work(ed) in SSA, we illustrate how their care practices are produced through the interaction of people and things. We emphasize the importance of context in shaping their practices, including the shortage of embryologists, the need to set up 'first' clinics in their respective countries, the paucity of trained counsellors in clinics and the mobility of IVF staff. The embryologists we interviewed performed multiple tasks on top of their laboratory work, including entrepreneurial tasks, advocacy, training, development of regulations, mentoring and patient counselling. They enacted care in several ways, towards gametes and embryos, patients, clinics and the profession. These multiple tasks and care practices make for dynamic and fulfilling careers of the interviewed embryologists but also stretch their capacities. They also raise questions about their contribution to the scarcity of embryological work in SSA. If access to IVF is to be achieved in the SSA region, more embryologists need to be trained and retained., Lay Summary: Embryologists play a central role in IVF. Yet, there is limited knowledge about the nature of their work. We examine the work of embryologists in SSA, where IVF clinics and embryologists are scarce. Based on qualitative interviews conducted with 12 embryologists, we illustrate the multiple tasks they perform on top of their laboratory work: entrepreneurial tasks, advocacy, training, development of regulations, mentoring and patient counselling. Context is important in shaping these practices. This includes the shortage of embryologists in the SSA region, the need to set up 'first' clinics in their respective countries, the lack of trained counsellors in clinics and the mobility of IVF staff. These multiple tasks, while professionally fulfilling, raise questions about their contribution to the scarcity of embryological work in SSA, which contributes to the limited access to IVF in this region.
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- 2025
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157. Access to assisted reproductive technologies in sub-Saharan Africa: fertility professionals' views.
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Whittaker A, Gerrits T, Hammarberg K, and Manderson L
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- Humans, Africa South of the Sahara, Female, Attitude of Health Personnel, Interviews as Topic, Male, Qualitative Research, Reproductive Techniques, Assisted economics, Health Services Accessibility
- Abstract
Across sub-Saharan Africa, there remains disagreement among local expert providers over the best ways to improve access to assisted reproduction in low-income contexts. Semi-structured qualitative interviews were conducted between 2021 and 2023 with 19 fertility specialists and 11 embryologists and one clinic manager from South Africa, Zimbabwe, Namibia, Kenya, Ethiopia and Uganda to explore issues surrounding access and potential low-cost IVF options. Lack of access to ART was variously conceptualised as a problem of high cost of treatment; lack of public funding for medical services and medication; poor policy awareness and prioritisation of fertility problems; a shortage of ART clinics and well-trained expert staff; the need for patients to travel long distances; and over-servicing within the largely privatised sector. All fertility specialists agreed that government funding for public sector assisted reproduction services was necessary to address access in the region. Other suggestions included: reduced medication costs by using mild stimulation protocols and oocyte retrievals under sedation instead of general anaesthetics. Insufficient data on low-cost interventions was cited as a barrier to their implementation. The lack of skilled embryologists on the continent was considered a major limitation to expanding ART services and the success of low-cost IVF systems. Very few specialists suggested that profits of pharmaceutical companies or ART clinics might be reduced to lessen the costs of treatments.
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- 2024
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158. mHealth technologies for pregnancy prevention: A challenge for patient-centred contraceptive counselling in Dutch general practice.
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Algera E, Leusink P, Gerrits T, Pols J, and Ravesloot JH
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- Female, Pregnancy, Humans, Contraceptive Agents, Counseling, General Practice, General Practitioners, Telemedicine
- Abstract
Background: A general practitioner (GP) standardly provides contraceptive counselling and care in the Netherlands. Recent years have seen the rise of mobile health technologies that aim to prevent pregnancy based on fertility awareness-based methods (FABMs). We lack high-quality evidence of these methods' effectiveness and clarity on how healthcare professionals include them in contraceptive counselling., Objectives: To analyse how Dutch healthcare professionals include pregnancy-prevention mobile health technologies (mHealth contraception) in contraceptive counselling and to propose practice recommendations based on our findings., Methods: We used ethnographic methods, including semi-structured interviews with nine professionals who were recruited using purposive sampling, 10 observations of contraceptive counselling by four professionals, six observations of teaching sessions in medical training on contraception and reproductive health, one national clinical guideline, and seven Dutch patient decision aids. Data were collected between 2018 and 2021 and analysed inductively using praxiographic and thematic analysis., Results: In contraceptive counselling and care, professionals tended to blend two approaches: 1) individual patient-tailored treatment and 2) risk minimisation. When interviewed about mHealth contraception, most professionals prioritised risk minimisation and forewent tailored treatment. Some did not consider mHealth contraception or FABMs as contraceptives or deemed them inferior methods., Conclusion: To minimise risk of unintended pregnancy, professionals hesitated to include mHealth contraception or other FABMs in contraceptive consultations. This may hamper adequate patient-centred counselling for patients with preference for mHealth contraception.Based on these results, we proposed recommendations that foster a patient-tailored approach to mHealth contraceptives.
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- 2024
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159. Antisense oligonucleotide-mediated terminal intron retention of endoglin: A potential strategy to inhibit renal interstitial fibrosis.
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Gerrits T, Dijkstra KL, Bruijn JA, Scharpfenecker M, Bijkerk R, and Baelde HJ
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- Humans, Male, Fibronectins metabolism, Fibronectins genetics, Female, Actins metabolism, Actins genetics, Middle Aged, Animals, Collagen Type I genetics, Collagen Type I metabolism, Alternative Splicing, Fibroblasts metabolism, Fibroblasts pathology, RNA, Messenger genetics, RNA, Messenger metabolism, Mice, Cell Line, Fibrosis, Endoglin metabolism, Endoglin genetics, Oligonucleotides, Antisense pharmacology, Oligonucleotides, Antisense genetics, Introns genetics, Transforming Growth Factor beta1 metabolism, Transforming Growth Factor beta1 genetics, Kidney metabolism, Kidney pathology
- Abstract
TGF-β is considered an important cytokine in the development of interstitial fibrosis in chronic kidney disease. The TGF-β co-receptor endoglin (ENG) tends to be upregulated in kidney fibrosis. ENG has two membrane bound isoforms generated via alternative splicing. Long-ENG was shown to enhance the extent of renal fibrosis in an unilateral ureteral obstruction mouse model, while short-ENG inhibited renal fibrosis. Here we aimed to achieve terminal intron retention of endoglin using antisense-oligo nucleotides (ASOs), thereby shifting the ratio towards short-ENG to inhibit the TGF-β1-mediated pro-fibrotic response. We isolated mRNA from kidney biopsies of patients with chronic allograft disease (CAD) (n = 12) and measured total ENG and short-ENG mRNA levels. ENG mRNA was upregulated 2.3 fold (p < 0.05) in kidneys of CAD patients compared to controls, while the percentage short-ENG of the total ENG mRNA was significantly lower (1.8 fold; p < 0.05). Transfection of ASOs that target splicing regulatory sites of ENG into TK173 fibroblasts led to higher levels of short-ENG (2 fold; p < 0.05). In addition, we stimulated these cells with TGF-β1 and measured a decrease in upregulation of ACTA2, COL1A1 and FN1 mRNA levels, and protein expression of αSMA, collagen type I, and fibronectin. These results show a potential for ENG ASOs as a therapy to reduce interstitial fibrosis in CKD., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier B.V. All rights reserved.)
- Published
- 2024
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160. Entangled photon pair generation in an integrated SiC platform.
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Rahmouni A, Wang R, Li J, Tang X, Gerrits T, Slattery O, Li Q, and Ma L
- Abstract
Entanglement plays a vital role in quantum information processing. Owing to its unique material properties, silicon carbide recently emerged as a promising candidate for the scalable implementation of advanced quantum information processing capabilities. To date, however, only entanglement of nuclear spins has been reported in silicon carbide, while an entangled photon source, whether it is based on bulk or chip-scale technologies, has remained elusive. Here, we report the demonstration of an entangled photon source in an integrated silicon carbide platform for the first time. Specifically, strongly correlated photon pairs are efficiently generated at the telecom C-band wavelength through implementing spontaneous four-wave mixing in a compact microring resonator in the 4H-silicon-carbide-on-insulator platform. The maximum coincidence-to-accidental ratio exceeds 600 at a pump power of 0.17 mW, corresponding to a pair generation rate of (9 ± 1) × 10
3 pairs/s. Energy-time entanglement is created and verified for such signal-idler photon pairs, with the two-photon interference fringes exhibiting a visibility larger than 99%. The heralded single-photon properties are also measured, with the heralded g(2) (0) on the order of 10-3 , demonstrating the SiC platform as a prospective fully integrated, complementary metal-oxide-semiconductor compatible single-photon source for quantum applications., (© 2024. The Author(s).)- Published
- 2024
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161. Synchronized source of indistinguishable photons for quantum networks.
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Lal N, Burenkov IA, Li-Baboud YS, Jabir MV, Kuo PS, Gerrits T, Slattery O, and Polyakov SV
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We present a source of indistinguishable photons at telecom wavelength, synchronized to an external clock, for the use in distributed quantum networks. We characterize the indistinguishability of photons generated in independent parametric down-conversion events using a Hong-Ou-Mandel interferometer, and show non-classical interference with coalescence, C = 0.83(5). We also demonstrate the synchronization to an external clock within sub-picosecond timing jitter, which is significantly shorter than the single-photon wavepacket duration of ≈ 35 ps. Our source enables scalable quantum protocols over multi-node, long-distance optical networks using network-based clock recovery systems.
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- 2024
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162. IntenSelect+: Enhancing Score-Based Selection in Virtual Reality.
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Kruger M, Gerrits T, Romer T, Kuhlen T, and Weissker T
- Abstract
Object selection in virtual environments is one of the most common and recurring interaction tasks. Therefore, the used technique can critically influence a system's overall efficiency and usability. IntenSelect is a scoring-based selection-by-volume technique that was shown to offer improved selection performance over conventional raycasting in virtual reality. This initial method, however, is most pronounced for small spherical objects that converge to a point-like appearance only, is challenging to parameterize, and has inherent limitations in terms of flexibility. We present an enhanced version of IntenSelect called IntenSelect+ designed to overcome multiple shortcomings of the original IntenSelect approach. In an empirical within-subjects user study with 42 participants, we compared IntenSelect+ to IntenSelect and conventional raycasting on various complex object configurations motivated by prior work. In addition to replicating the previously shown benefits of IntenSelect over raycasting, our results demonstrate significant advantages of IntenSelect+ over IntenSelect regarding selection performance, task load, and user experience. We, therefore, conclude that IntenSelect+ is a promising enhancement of the original approach that enables faster, more precise, and more comfortable object selection in immersive virtual environments.
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- 2024
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163. Breaking the silence around infertility: a scoping review of interventions addressing infertility-related gendered stigmatisation in low- and middle-income countries.
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Gerrits T, Kroes H, Russell S, and van Rooij F
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- Male, Humans, Female, Stereotyping, Social Stigma, Counseling, Developing Countries, Infertility, Female
- Abstract
Infertility is a reproductive health concern that deserves attention, as reconfirmed by the 2018 report of the Guttmacher- Lancet Commission on Sexual and Reproductive Health and Rights (SRHR). However, governments and SRHR organisations tend to neglect infertility. We conducted a scoping review of existing interventions aiming to decrease the stigmatisation of infertility in low- and middle-income countries (LMICs). The review consisted of a combination of research methods: academic database (Embase, Socological abstracts, google scholar; resulting in 15 articles), Google and social media searches, and primary data collection (18 key informant interviews and 3 focus group discussions). The results distinguish between infertility stigma interventions targeted at intrapersonal, interpersonal and structural levels of stigma. The review shows that published studies on interventions tackling infertility stigmatisation in LMICs are rare. Nevertheless, we found several interventions at intra- and interpersonal levels aiming to support women and men to cope with and mitigate infertility stigmatisation (e.g. counselling, telephone hotlines, and support groups). A limited number of interventions addressed stigmatisation at a structural level (e.g. empowering infertile women to become financially independent). The review suggests that infertility destigmatisation interventions need to be implemented across all levels. Interventions geared to individuals experiencing infertility should include women and men and also be offered beyond the clinical setting; and interventions should also aim to combat stigmatising attitudes of family or community members. At the structural level, interventions could aim to empower women, reshape masculinities and improve access to and quality of comprehensive fertility care. Interventions should be undertaken by policymakers, professionals, activists, and others working on infertility in LMICs, and accompanied with evaluation research to assess their effectiveness.
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- 2023
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164. Synchronization and coexistence in quantum networks.
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Burenkov IA, Semionov A, Hala, Gerrits T, Rahmouni A, Anand DJ, Li-Baboud YS, Slattery O, Battou A, and Polyakov SV
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We investigate the coexistence of clock synchronization protocols with quantum signals in a common single-mode optical fiber. By measuring optical noise between 1500 nm to 1620 nm we demonstrate a potential for up to 100 quantum, 100 GHz wide channels coexisting with the classical synchronization signals. Both "White Rabbit" and pulsed laser-based synchronization protocols were characterized and compared. We establish a theoretical limit of the fiber link length for coexisting quantum and classical channels. The maximal fiber length is below approximately 100 km for off-the-shelf optical transceivers and can be significantly improved by taking advantage of quantum receivers.
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- 2023
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165. 'Doing' kinship: heterosexual parents' experiences of non-genetic parenthood through donor conception.
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Siermann M, Visser M, Schrijvers A, Mochtar M, and Gerrits T
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- Child, Humans, Male, Female, Heterosexuality, Prospective Studies, Semen, Parents, Donor Conception, Insemination, Artificial, Heterologous
- Abstract
Research Question: How do Dutch heterosexual parents who achieved parenthood through donor conception navigate non-genetic parenthood and kinship?, Design: A qualitative in-depth semi-structured interview study was performed between September 2018 and January 2019 with both partners of 13 Dutch heterosexual couples where the male partner suffered from infertility and who conceived a child with the help of a sperm donor. Interview questions were based on literature and clinical experiences of experts in the field of donor conception. Interviews were transcribed and analysed using thematic analysis., Results: All parents navigated non-genetic parenthood through 'doing' kinship: they negotiated the importance of nature versus nurture with regards to donor conception and non-genetic parenthood. Most parents perceived genetics as irrelevant for experiencing parenthood, bonding with their children and the preferred role of the donor in their future lives. Yet most of them found genetics relevant for generating similarities between the father and the child, and for wanting the same donor for all their children to ensure a full genetic relation among them. Additionally, based on the donor's genetic bond with the child, some men were anxious about the donor's role in the child's future life and the consequences for their position as a non-genetic father. A few women perceived genetics as relevant in terms of possible inherited illnesses from the donor., Conclusions: Parents experienced several ambiguities regarding the role of genetics in donor conception and navigated 'doing' kinship in various ways. These aspects need to be taken into consideration during the counselling of prospective parents planning to conceive with donor conception., (Copyright © 2022 Reproductive Healthcare Ltd. Published by Elsevier Ltd. All rights reserved.)
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- 2023
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166. Endoglin Is an Important Mediator in the Final Common Pathway of Chronic Kidney Disease to End-Stage Renal Disease.
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Gerrits T, Brouwer IJ, Dijkstra KL, Wolterbeek R, Bruijn JA, Scharpfenecker M, and Baelde HJ
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- Humans, Endothelial Cells metabolism, Fibrosis, Kidney metabolism, Receptors, Growth Factor metabolism, RNA, Messenger metabolism, Transforming Growth Factor beta metabolism, Diabetic Nephropathies metabolism, Endoglin genetics, Endoglin metabolism, Kidney Failure, Chronic pathology, Renal Insufficiency, Chronic metabolism
- Abstract
Chronic kidney disease (CKD) is a slow-developing, progressive deterioration of renal function. The final common pathway in the pathophysiology of CKD involves glomerular sclerosis, tubular atrophy and interstitial fibrosis. Transforming growth factor-beta (TGF-β) stimulates the differentiation of fibroblasts towards myofibroblasts and the production of extracellular matrix (ECM) molecules, and thereby interstitial fibrosis. It has been shown that endoglin (ENG, CD105), primarily expressed in endothelial cells and fibroblasts, can function as a co-receptor of TGF signaling. In several human organs, endoglin tends to be upregulated when chronic damage and fibrosis is present. We hypothesize that endoglin is upregulated in renal interstitial fibrosis and plays a role in the progression of CKD. We first measured renal endoglin expression in biopsy samples obtained from patients with different types of CKD, i.e., IgA nephropathy, focal segmental glomerulosclerosis (FSGS), diabetic nephropathy (DN) and patients with chronic allograft dysfunction (CAD). We showed that endoglin is upregulated in CAD patients (p < 0.001) and patients with DN (p < 0.05), compared to control kidneys. Furthermore, the amount of interstitial endoglin expression correlated with eGFR (p < 0.001) and the amount of interstitial fibrosis (p < 0.001), independent of the diagnosis of the biopsies. Finally, we investigated in vitro the effect of endoglin overexpression in TGF-β stimulated human kidney fibroblasts. Overexpression of endoglin resulted in an enhanced ACTA2, CCN2 and SERPINE1 mRNA response (p < 0.05). It also increased the mRNA and protein upregulation of the ECM components collagen type I (COL1A1) and fibronectin (FN1) (p < 0.05). Our results suggest that endoglin is an important mediator in the final common pathway of CKD and could be used as a possible new therapeutic target to counteract the progression towards end-stage renal disease (ESRD).
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- 2022
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167. Multifaceted Visual Analysis of Oceanographic Simulation Ensemble Data.
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Rave H, Fincke J, Averkamp S, Tangerding B, Wehrenberg LP, Gerrits T, Huesmann K, Leistikow S, and Linsen L
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- Computer Simulation, Oceanography
- Abstract
The analysis of multirun oceanographic simulation data imposes various challenges ranging from visualizing multifield spatio-temporal data over properly identifying and depicting vortices to visually representing uncertainties. We present an integrated interactive visual analysis tool that enables us to overcome these challenges by employing multiple coordinated views of different facets of the data at different levels of aggregation.
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- 2022
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168. Calibration and comparison of detection efficiency for free-space single-photon avalanche diodes at 850 nm.
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Jin J, Gerrits T, and Gamouras A
- Abstract
A detection efficiency measurement system for free-space single-photon detectors has been established at the National Research Council (NRC) Canada. This measurement apparatus incorporates an 850 nm fiber laser source and utilizes a double-attenuation and substitution calibration technique. Detection efficiency calibrations of silicon single-photon avalanche photodiodes (SPADs) at incident photon rates in the range of 1.0×10
5 photon counts per second (Cts/s) (36 fW) to 2.1×106 C t s / s (734 fW) are SI-traceable through the substitution configuration with a silicon transfer standard detector, calibrated directly using the NRC absolute cryogenic radiometer. The measurement approach taken by the NRC was compared with the SPAD calibration technique implemented at the National Institute of Standards and Technology (NIST) in the United States. The count-rate-dependent detection efficiency of a silicon SPAD was measured at NIST and compared with results from the same SPAD measured at NRC within the range of incident photon rates from 1×105 C t s / s to 5×105 C t s / s . Comparison of the calibration results shows agreement between the two laboratories within the combined measurement uncertainties.- Published
- 2022
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169. Quantum computational advantage with a programmable photonic processor.
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Madsen LS, Laudenbach F, Askarani MF, Rortais F, Vincent T, Bulmer JFF, Miatto FM, Neuhaus L, Helt LG, Collins MJ, Lita AE, Gerrits T, Nam SW, Vaidya VD, Menotti M, Dhand I, Vernon Z, Quesada N, and Lavoie J
- Abstract
A quantum computer attains computational advantage when outperforming the best classical computers running the best-known algorithms on well-defined tasks. No photonic machine offering programmability over all its quantum gates has demonstrated quantum computational advantage: previous machines
1,2 were largely restricted to static gate sequences. Earlier photonic demonstrations were also vulnerable to spoofing3 , in which classical heuristics produce samples, without direct simulation, lying closer to the ideal distribution than do samples from the quantum hardware. Here we report quantum computational advantage using Borealis, a photonic processor offering dynamic programmability on all gates implemented. We carry out Gaussian boson sampling4 (GBS) on 216 squeezed modes entangled with three-dimensional connectivity5 , using a time-multiplexed and photon-number-resolving architecture. On average, it would take more than 9,000 years for the best available algorithms and supercomputers to produce, using exact methods, a single sample from the programmed distribution, whereas Borealis requires only 36 μs. This runtime advantage is over 50 million times as extreme as that reported from earlier photonic machines. Ours constitutes a very large GBS experiment, registering events with up to 219 photons and a mean photon number of 125. This work is a critical milestone on the path to a practical quantum computer, validating key technological features of photonics as a platform for this goal., (© 2022. The Author(s).)- Published
- 2022
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170. Reproductive travel to, from and within sub-Saharan Africa: A scoping review.
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Moll T, Gerrits T, Hammarberg K, Manderson L, and Whittaker A
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Scholarly interest in reproductive travel has increased in recent years, but travel within, to and from the African continent has received much less attention. We reviewed the literature on cross-border reproductive travel to and from countries of sub-Saharan Africa in order to understand the local forms of this trade. Access to fertility care remains deeply stratified, which is an ongoing concern in a region with some of the highest rates of infertility. We found a wide variety of reasons for reproductive travel, including a lack of trusted local clinics. Destinations were chosen for reasons including historical movements for medical treatment broadly, diasporic circulations, pragmatic language reasons, and ties of former colonial relations. We describe the unique tempos of treatment in the region, ranging from some intended parents staying in receiving countries for some years to the short-term contingent support networks that reprotravellers develop during their treatment and travel. Unique to the region is the movement of medical professionals, such as the 'fly-in, fly-out' clinic staff to deliver fertility care. Future research should include practices and movements to presently neglected 'reprohubs', particularly Kenya and Nigeria; the impact of pandemic-related lockdowns and border closures on the movements of intended parents, reproductive assistors and reproductive material; and the impact of low-cost protocols on treatment access within the region. This scoping review provides insight into the relevant work on cross-border reproductive care in sub-Saharan Africa, where a unique combination of access factors, affordability, and sociocultural and geopolitical issues fashion individuals' and couples' cross-border reproductive travel within, to and from Africa., (© 2022 The Authors.)
- Published
- 2022
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171. Mixture model analysis of Transition Edge Sensor pulse height spectra.
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Coakley KJ, Splett J, and Gerrits T
- Abstract
To calibrate an optical transition edge sensor (TES), for each pulse of the light source (e.g. pulsed laser), one must determine the ratio of the expected number of photons that deposit energy and the expected number of photons created by the laser. Based on the estimated pulse height generated by each energy deposit, we form a pulse height spectrum with features corresponding to different numbers of deposited photons. We model the number of photons that deposit energy per laser pulse as a realization of a Poisson process, and the observed pulse height spectrum with a mixture model method. For each candidate feature set, we determine the expected number of photons that deposit energy per pulse and its associated uncertainty based on the mixture model weights corresponding to that candidate feature set. From training data, we select the optimal feature set according to an uncertainty minimization criterion. We then determine the expected number of photons that deposit energy per pulse and its associated uncertainty for test data that is independent of the training data. Our uncertainty budget accounts for random measurement errors, systematic effects due to mismodeling feature shapes in our mixture model, and possible imperfections in our feature set selection method., Competing Interests: Disclosures The authors declare no conflicts of interest.
- Published
- 2022
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172. Witnessing the survival of time-energy entanglement through biological tissue and scattering media.
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Lum DJ, Mazurek MD, Mikhaylov A, Parzuchowski KM, Wilson RN, Jimenez R, Gerrits T, Stevens MJ, Cicerone MT, and Camp CH Jr
- Abstract
We demonstrate the preservation of the time-energy entanglement of near-IR photons through thick biological media (≤1.55 mm) and tissue (≤ 235 μ m) at room temperature. Using a Franson-type interferometer, we demonstrate interferometric contrast of over 0.9 in skim milk, 2% milk, and chicken tissue. This work supports the many proposed opportunities for nonclassical light in biological imaging and analyses from sub-shot noise measurements to entanglement-enhanced fluorescence imaging, clearly indicating that the entanglement characteristics of photons can be maintained even after propagation through thick, turbid biological samples., Competing Interests: The authors declare no conflicts of interest., (© 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement.)
- Published
- 2021
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173. The relationship between stigmatisation and quality of life in Ghanaian women and men with fertility problems: mediating role of coping strategies.
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Van Rooij FB, Bos H, Gerrits T, Hiadzi RA, and Donkor ES
- Abstract
Introduction: Fertility problems may have a devastating impact on the people involved. Specifically, in highly pronatalist settings like Ghana, the personal and social consequences are high. This study focused on the relationship between stigmatisation because of fertility problems and quality of life among Ghanaian women and men, and the possible mediating role of coping strategies., Methods: Participants (38 women, 11 men) were recruited with the help of a patient organisation and a hospital in Accra. Standardised instruments were used to measure the stigmatisation of having fertility problems, fertility quality of life and coping with fertility problems. Partial Pearson r correlations were conducted, followed by bootstrapped mediation analyses (PROCESS macro)., Results: Stigmatisation was negatively correlated with fertility quality of life, and fertility quality of life was negatively correlated with active-avoidance coping. Active avoidance coping partially mediated the relationship between being stigmatised because of fertility problems and fertility quality of life., Conclusions: Professionals working with people with fertility problems should pay more attention to how people are coping with experiences of stigmatisation., Competing Interests: Disclosure of interest: The authors report no conflict of interest., (Copyright © 2020 Facts, Views & Vision.)
- Published
- 2021
174. Endoglin Promotes Myofibroblast Differentiation and Extracellular Matrix Production in Diabetic Nephropathy.
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Gerrits T, Zandbergen M, Wolterbeek R, Bruijn JA, Baelde HJ, and Scharpfenecker M
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- Aged, Autopsy, Biopsy, Cell Line, Cohort Studies, Female, Fibroblasts metabolism, Fibroblasts pathology, Humans, Kidney pathology, Male, Phosphorylation, RNA, Small Interfering metabolism, Signal Transduction, Smad Proteins metabolism, Transforming Growth Factor beta metabolism, Up-Regulation, Cell Differentiation, Diabetic Nephropathies metabolism, Diabetic Nephropathies pathology, Endoglin metabolism, Extracellular Matrix metabolism, Myofibroblasts metabolism, Myofibroblasts pathology
- Abstract
Diabetic nephropathy (DN) is a complication of diabetes mellitus that can lead to proteinuria and a progressive decline in renal function. Endoglin, a co-receptor of TGF-β, is known primarily for regulating endothelial cell function; however, endoglin is also associated with hepatic, cardiac, and intestinal fibrosis. This study investigates whether endoglin contributes to the development of interstitial fibrosis in DN. Kidney autopsy material from 80 diabetic patients was stained for endoglin and Sirius Red and scored semi-quantitatively. Interstitial endoglin expression was increased in samples with DN and was correlated with Sirius Red staining ( p < 0.001). Endoglin expression was also correlated with reduced eGFR ( p = 0.001), increased creatinine ( p < 0.01), increased systolic blood pressure ( p < 0.05), hypertension ( p < 0.05), and higher IFTA scores ( p < 0.001). Biopsy samples from DN patients were also co-immunostained for endoglin together with CD31, CD68, vimentin, or α-SMA Endoglin co-localized with both the endothelial marker CD31 and the myofibroblast marker α-SMA. Finally, we used shRNA to knockdown endoglin expression in a human kidney fibroblast cell line. We found that TGF-β1 stimulation upregulated SERPINE1 , CTGF , and ACTA2 mRNA and α-SMA protein, and that these effects were significantly reduced in fibroblasts after endoglin knockdown. Taken together, these data suggest that endoglin plays a role in the pathogenesis of interstitial fibrosis in DN., Competing Interests: The authors declare no conflict of interest.
- Published
- 2020
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175. The social and cultural meanings of infertility for men and women in Zambia: legacy, family and divine intervention.
- Author
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Howe S, Zulu JM, Boivin J, and Gerrits T
- Abstract
Despite the high prevalence of infertility within the sub-Saharan sterility belt, infertility in Zambia is understudied, particularly from a social perspective. Furthermore, few studies in sub-Saharan Africa include the infertility experiences of men. This article seeks to fill this gap by qualitatively describing the ways in which infertility in Zambia is socially and culturally loaded for both men and women. Demonstrating fertility is necessary to be considered a full adult, a real man or woman, and to leave a legacy after death. People in Zambia, including medical professionals, currently lack the necessary information and access to (or ability to provide) care to effectively resolve fertility issues. Infertile people manage their experience through a variety of social, emotional, spiritual, and medical strategies. However, no solution is considered adequate unless the intervention results in childbirth. In this way, infertility is about producing babies and the social meaning of that process, rather than the raising of children., Competing Interests: Conflict of Interest statement: The authors have no conflicts of interest to declare., (Copyright © 2020 Facts, Views & Vision.)
- Published
- 2020
176. Knowing what the patient wants: a hospital ethnography studying physician culture in shared decision making in the Netherlands.
- Author
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Spinnewijn L, Aarts J, Verschuur S, Braat D, Gerrits T, and Scheele F
- Subjects
- Anthropology, Cultural, Gynecology, Hospital Departments, Hospitals, University, Humans, Medical Oncology, Netherlands, Physician-Patient Relations, Decision Making, Shared, Patient Preference, Physicians
- Abstract
Objectives: To study physician culture in relation to shared decision making (SDM) practice., Design: Execution of a hospital ethnography, combined with interviews and a study of clinical guidelines. Ten-week observations by an insider (physician) and an outsider (student medical anthropology) observer. The use of French sociologist Bourdieu's 'Theory of Practice' and its description of habitus, field and capital, as a lens for analysing physician culture., Setting: The gynaecological oncology department of a university hospital in the Netherlands. Observations were executed at meetings, as well as individual patient contacts., Participants: Six gynaecological oncologists, three registrars and two specialised nurses. Nine of these professionals were also interviewed., Main Outcome Measures: Common elements in physician habitus that influence the way SDM is being implemented., Results: Three main elements of physician habitus were identified. First of all, the 'emphasis on medical evidence' in group meetings as well as in patient encounters. Second 'acting as a team', which confronts the patient with the recommendations of a whole team of professionals. And lastly 'knowing what the patient wants', which describes how doctors act on what they think is best for patients instead of checking what patients actually want. Results were viewed in the light of how physicians deal with uncertainty by turning to medical evidence, as well as how the educational system stresses evidence-based medicine. Observations also highlighted the positive attitude doctors actually have towards SDM., Conclusions: Certain features of physician culture hinder the correct implementation of SDM. Medical training and guidelines should put more emphasis on how to elicit patient perspective. Patient preferences should be addressed better in the patient workup, for example by giving them explicit attention first. This eventually could create a physician culture that is more helpful for SDM., Competing Interests: Competing interests: None declared., (© Author(s) (or their employer(s)) 2020. Re-use permitted under CC BY-NC. No commercial re-use. See rights and permissions. Published by BMJ.)
- Published
- 2020
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177. Improvisation and harm avoidance: An ethnographic study of adherence to postnatal care protocols in two hospitals in Southern Ghana.
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Yevoo LL, Agyepong IA, Gerrits T, and van Dijk H
- Subjects
- Anthropology, Cultural methods, Attitude of Health Personnel, Ghana, Guideline Adherence statistics & numerical data, Hospitals statistics & numerical data, Humans, Postnatal Care standards, Postnatal Care statistics & numerical data, Qualitative Research, Guideline Adherence standards, Harm Reduction, Postnatal Care methods
- Abstract
Providers' adherence to case management protocols can affect quality of care. However, how and why protocols are adhered to by frontline health workers in low- and middle-income countries is not always clear. This study explored midwives' adherence to national postnatal care protocols in two public hospitals in Southern Ghana using an ethnographic study design. Ninety participant observations and 88 conversations were conducted over a 20-months period, and two group interviews held with the midwives in the two hospitals. Data was analysed using a grounded theory approach. Findings: Midwives collectively decided when to adhere, modify or totally ignore postnatal care protocols. Adherence often occurred if required resources (equipment, tools, supplies) were available. Modification occurred when midwives felt that strict adherence could have negative implications for patients and they could be seen as acting 'unprofessionally'. Ignoring or modifying protocols also occurred when midwives were uncertain of the patient's health condition; basic supplies, logistics and infrastructure needed for adherence were unavailable or inappropriate; or midwives felt they might expose themselves or their clients to physical, psychological, emotional, financial or social harm. Regardless of the reasons that midwives felt justified to ignore or modify postnatal care protocols, it appeared in many instances to lead to the provision of care of suboptimal quality. Conclusion and recommendations: Providing clinical decision-making protocols is not enough to improve mother and new born care quality and outcomes. Faced with constraining conditions of work, providers are likely to modify guidelines as part of coping behaviour. Addressing constraining conditions of work must accompany guidelines. This includes adequate risks protection for health workers and clients; and resolution of deficits in essential equipment, infrastructure, supplies and staffing., Competing Interests: Declaration of Competing Interest None., (Copyright © 2019. Published by Elsevier Ltd.)
- Published
- 2020
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178. Detector-Agnostic Phase-Space Distributions.
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Sperling J, Phillips DS, Bulmer JFF, Thekkadath GS, Eckstein A, Wolterink TAW, Lugani J, Nam SW, Lita A, Gerrits T, Vogel W, Agarwal GS, Silberhorn C, and Walmsley IA
- Abstract
The representation of quantum states via phase-space functions constitutes an intuitive technique to characterize light. However, the reconstruction of such distributions is challenging as it demands specific types of detectors and detailed models thereof to account for their particular properties and imperfections. To overcome these obstacles, we derive and implement a measurement scheme that enables a reconstruction of phase-space distributions for arbitrary states whose functionality does not depend on the knowledge of the detectors, thus defining the notion of detector-agnostic phase-space distributions. Our theory presents a generalization of well-known phase-space quasiprobability distributions, such as the Wigner function. We implement our measurement protocol, using state-of-the-art transition-edge sensors without performing a detector characterization. Based on our approach, we reveal the characteristic features of heralded single- and two-photon states in phase space and certify their nonclassicality with high statistical significance.
- Published
- 2020
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179. Quantum-enhanced interferometry with large heralded photon-number states.
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Thekkadath GS, Mycroft ME, Bell BA, Wade CG, Eckstein A, Phillips DS, Patel RB, Buraczewski A, Lita AE, Gerrits T, Nam SW, Stobińska M, Lvovsky AI, and Walmsley IA
- Abstract
Quantum phenomena such as entanglement can improve fundamental limits on the sensitivity of a measurement probe. In optical interferometry, a probe consisting of N entangled photons provides up to a N enhancement in phase sensitivity compared to a classical probe of the same energy. Here, we employ high-gain parametric down-conversion sources and photon-number-resolving detectors to perform interferometry with heralded quantum probes of sizes up to N = 8 (i.e. measuring up to 16-photon coincidences). Our probes are created by injecting heralded photon-number states into an interferometer, and in principle provide quantum-enhanced phase sensitivity even in the presence of significant optical loss. Our work paves the way towards quantum-enhanced interferometry using large entangled photonic states., Competing Interests: COMPETING INTERESTS The authors declare no competing interests.
- Published
- 2020
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180. Calibration of free-space and fiber-coupled single-photon detectors.
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Gerrits T, Migdall A, Bienfang JC, Lehman J, Nam SW, Splett J, Vayshenker I, and Wang J
- Abstract
We measure the detection efficiency of single-photon detectors at wavelengths near 851 nm and 1533.6 nm. We investigate the spatial uniformity of one free-space-coupled single-photon avalanche diode and present a comparison between fusion-spliced and connectorized fiber-coupled single-photon detectors. We find that our expanded relative uncertainty for a single measurement of the detection efficiency is as low as 0.70% for fiber-coupled measurements at 1533.6 nm and as high as 1.78% for our free-space characterization at 851.7 nm. The detection-efficiency determination includes corrections for afterpulsing, dark count, and count-rate effects of the single-photon detector with the detection efficiency interpolated to operation at a specified detected count rate.
- Published
- 2020
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181. Less is more: On-board lossy compression of accelerometer data increases biologging capacity.
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Nuijten RJM, Gerrits T, Shamoun-Baranes J, and Nolet BA
- Subjects
- Animals, Seasons, Accelerometry, Behavior, Animal
- Abstract
GPS-tracking devices have been used in combination with a wide range of additional sensors to study animal behaviour, physiology and interaction with their environment. Tri-axial accelerometers allow researchers to remotely infer the behaviour of individuals, at all places and times. Collection of accelerometer data is relatively cheap in terms of energy usage, but the amount of raw data collected generally requires much storage space and is particularly demanding in terms of energy needed for data transmission. Here, we propose compressing the raw accelerometer (ACC) data into summary statistics within the tracking device (before transmission) to reduce data size, as a means to overcome limitations in storage and energy capacity. We explored this type of lossy data compression in the accelerometer data of tagged Bewick's swans Cygnus columbianus bewickii collected in spring 2017. Using software settings in which bouts of 2 s of both raw ACC data and summary statistics were collected in parallel but with different bout intervals to keep total data size comparable, we created the opportunity for a direct comparison of time budgets derived by the two data collection methods. We found that the data compression in our case yielded a six times reduction in data size per bout, and concurrent, similar decreases in storage and energy use of the device. We show that with the same accuracy of the behavioural classification, the freed memory and energy of the device can be used to increase the monitoring effort, resulting in a more detailed representation of the individuals' time budget. Rare and/or short behaviours, such as daily roost flights, were picked up significantly more when collecting summary statistics instead of raw ACC data (but note differences in sampling rate). Such level of detail can be of essential importance, for instance to make a reliable estimate of the energy budgets of individuals. In conclusion, we argue that this type of lossy data compression can be a well-considered choice in study situations where limitations in energy and storage space of the device pose a problem. Ultimately, these developments can allow for long-term and nearly continuous remote monitoring of the behaviour of free-ranging animals., (© 2019 The Authors. Journal of Animal Ecology published by John Wiley & Sons Ltd on behalf of British Ecological Society.)
- Published
- 2020
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182. Counsellors' practices in donor sperm treatment.
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Visser M, Gerrits T, van der Veen F, and Mochtar M
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- Adult, Counseling methods, Decision Making, Disclosure, Female, Focus Groups, Humans, Male, Middle Aged, Policy, Counseling organization & administration, Counselors, Sperm Banks, Tissue Donors psychology
- Abstract
When intended parents choose to have donor sperm treatment (DST), this may entail wide-ranging and long-lasting psychosocial implications related to the social parent not having a genetic tie with the child, how to disclose donor-conception and future donor contact. Counselling by qualified professionals is recommended to help intended parents cope with these implications. The objective of this study is to present findings and insights about how counsellors execute their counselling practices. We performed a qualitative study that included 13 counsellors working in the 11 clinics offering DST in the Netherlands. We held a focus group discussion and individual face-to-face semi-structured interviews, which were fully transcribed and analysed using thematic analysis. The counsellors combined screening for eligibility and guidance within one session. They acted according to their individual knowledge and clinical experience and had different opinions on the issues they discussed with intended parents, which resulted in large practice variations. The counsellors were dependent on the admission policies of the clinics, which were mainly limited to regulating access to psychosocial counselling, which also lead to a variety of counselling practices. This means that evidence-based guidelines on counselling in DST need to be developed to provide consistent counselling with less practice variation.
- Published
- 2019
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183. Quantum interference enables constant-time quantum information processing.
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Stobińska M, Buraczewski A, Moore M, Clements WR, Renema JJ, Nam SW, Gerrits T, Lita A, Kolthammer WS, Eckstein A, and Walmsley IA
- Abstract
It is an open question how fast information processing can be performed and whether quantum effects can speed up the best existing solutions. Signal extraction, analysis, and compression in diagnostics, astronomy, chemistry, and broadcasting build on the discrete Fourier transform. It is implemented with the fast Fourier transform (FFT) algorithm that assumes a periodic input of specific lengths, which rarely holds true. A lesser-known transform, the Kravchuk-Fourier (KT), allows one to operate on finite strings of arbitrary length. It is of high demand in digital image processing and computer vision but features a prohibitive runtime. Here, we report a one-step computation of a fractional quantum KT. The quantum d -nary (qudit) architecture we use comprises only one gate and offers processing time independent of the input size. The gate may use a multiphoton Hong-Ou-Mandel effect. Existing quantum technologies may scale it up toward diverse applications.
- Published
- 2019
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184. Indistinguishable single-mode photons from spectrally engineered biphotons.
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Chen C, Heyes JE, Hong KH, Niu MY, Lita AE, Gerrits T, Nam SW, Shapiro JH, and Wong FNC
- Abstract
We use pulsed spontaneous parametric down-conversion in KTiOPO
4 , with a Gaussian phase-matching function and a transform-limited Gaussian pump, to achieve near-unity spectral purity in heralded single photons at telecommunication wavelength. Theory shows that these phase-matching and pump conditions are sufficient to ensure that a biphoton state with a circularly symmetric joint spectral intensity profile is transform limited and factorable. We verify the heralded-state spectral purity in a four-fold coincidence measurement by performing Hong-Ou-Mandel interference between two independently generated heralded photons. With a mild spectral filter we obtain an interference visibility of 98.4±1.1% which corresponds to a heralded-state purity of 99.2%. Our heralded photon source is potentially an essential resource for measurement-based quantum information processing and quantum network applications.- Published
- 2019
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185. Being a donor-child: wishes for parental support, peer support and counseling.
- Author
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Schrijvers A, Bos H, van Rooij F, Gerrits T, van der Veen F, Mochtar M, and Visser M
- Subjects
- Adolescent, Adult, Female, Humans, Insemination, Artificial, Heterologous psychology, Interviews as Topic, Male, Netherlands, Tissue Donors psychology, Young Adult, Counseling, Disclosure, Donor Conception psychology, Parents, Peer Group
- Abstract
Objectives: We aimed at exploring the wishes of Dutch donor-conceived offspring for parental support, peer support and counseling and sought to contribute to the improvement of health care for all parties involved with assisted reproductive technologies., Methods: We held semi-structured in-depth interviews with 24 donor-conceived offspring (M
age = 26.9, range 17-41) born within father-mother, two-mother and single mother families. The majority of the donor offspring was conceived with semen of anonymous donors. All offspring were recruited by network organizations and snowball sampling. The interviews were fully transcribed and analyzed using the constant comparative method., Results: Donor-conceived offspring wished that their parents had talked openly about donor conception and had missed parental support. They wished that their parents would have received counseling before donor sperm treatment on how to talk with their children about donor conception in several stages of life. They valued the availability of peer contact to exchange stories with other donor-conceived offspring and would have liked assistance in getting access to trustworthy information about characteristics and identifying information of their donor. Donor-conceived offspring wished to know where to find specialist counseling when needed., Conclusions: Peer support and counseling by professionals for donor-conceived offspring should be available for those who need it. The findings also support professional counseling for intended parents before treatment to improve parental support for donor-children.- Published
- 2019
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186. Endoglin Mediates Vascular Endothelial Growth Factor-A-Induced Endothelial Cell Activation by Regulating Akt Signaling.
- Author
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Bus P, Gerrits T, Heemskerk SAC, Zandbergen M, Wolterbeek R, Bruijn JA, Baelde HJ, and Scharpfenecker M
- Subjects
- Animals, Diabetes Mellitus, Type 1 complications, Diabetic Nephropathies etiology, Diabetic Nephropathies metabolism, Endoglin genetics, Endothelium, Vascular metabolism, Female, Gene Expression Regulation, Humans, Kidney Glomerulus metabolism, Kidney Glomerulus pathology, Male, Mice, Mice, Inbred C57BL, Phosphorylation, Proto-Oncogene Proteins c-akt genetics, Signal Transduction, Vascular Cell Adhesion Molecule-1 genetics, Vascular Endothelial Growth Factor A genetics, Diabetes Mellitus, Experimental complications, Diabetic Nephropathies pathology, Endoglin metabolism, Endothelium, Vascular pathology, Proto-Oncogene Proteins c-akt metabolism, Vascular Cell Adhesion Molecule-1 metabolism, Vascular Endothelial Growth Factor A metabolism
- Abstract
In diabetic nephropathy, differential expression of growth factors leads to vascular changes, including endothelial cell activation, monocyte infiltration, and inflammation. Endoglin plays an important role in endothelial function and is also associated with inflammation. In the kidney, vascular endoglin expression is increased in animal models of renal injury, where it contributes to disease severity, possibly by promoting endothelial cell activation and inflammation. Herein, we investigated whether endoglin expression is associated with diabetic nephropathy. In addition, we examined whether reducing endothelial endoglin expression in vitro affects endothelial cell activation and monocyte adhesion and, if so, which intracellular pathways are involved. Finally, we analyzed whether glomerular endoglin expression is correlated with endothelial cell activation in patients with diabetic nephropathy. Endoglin levels were significantly increased in mice with type 1 diabetes compared with control mice. Reducing endoglin expression in cultured endothelial cells significantly impaired the vascular endothelial growth factor-A-induced up-regulation of activation markers and monocyte adhesion. This was mediated by increased phosphorylation of Akt, thereby inhibiting activating transcription factor 2 phosphorylation, which regulates vascular cell adhesion molecule-1 (VCAM1) gene transcription in these cells. Last, endoglin colocalized with VCAM-1 in the glomeruli of diabetic patients, glomerular VCAM-1 expression was significantly increased in these patients, and this increase in VCAM-1 expression was correlated with increased glomerular endoglin expression. Thus, targeting endoglin function may have therapeutic value in patients at risk for diabetic nephropathy., (Copyright © 2018 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.)
- Published
- 2018
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187. Multi-pulse fitting of transition edge sensor signals from a near-infrared continuous-wave source.
- Author
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Lee J, Shen L, Cerè A, Gerrits T, Lita AE, Nam SW, and Kurtsiefer C
- Abstract
Transition-edge sensors (TESs) are photon-number resolving calorimetric spectrometers with near unit efficiency. Their recovery time, which is on the order of microseconds, limits the number resolving ability and timing accuracy in high photon-flux conditions. This is usually addressed by pulsing the light source or discarding overlapping signals, thereby limiting its applicability. We present an approach to assign detection times to overlapping detection events in the regime of low signal-to-noise ratio, as in the case of TES detection of near-infrared radiation. We use a two-level discriminator, inherently robust against noise, to coarsely locate pulses in time and timestamp individual photoevents by fitting to a heuristic model. As an example, we measure the second-order time correlation of a coherent source in a single spatial mode using a single TES detector.
- Published
- 2018
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188. Randomness Extraction from Bell Violation with Continuous Parametric Down-Conversion.
- Author
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Shen L, Lee J, Thinh LP, Bancal JD, Cerè A, Lamas-Linares A, Lita A, Gerrits T, Nam SW, Scarani V, and Kurtsiefer C
- Abstract
We present a violation of the Clauser-Horne-Shimony-Holt inequality without the fair sampling assumption with a continuously pumped photon pair source combined with two high efficiency superconducting detectors. Because of the continuous nature of the source, the choice of the duration of each measurement round effectively controls the average number of photon pairs participating in the Bell test. We observe a maximum violation of S=2.016 02(32) with an average number of pairs per round of ≈0.32, compatible with our system overall detection efficiencies. Systems that violate a Bell inequality are guaranteed to generate private randomness, with the randomness extraction rate depending on the observed violation and on the repetition rate of the Bell test. For our realization, the optimal rate of randomness generation is a compromise between the observed violation and the duration of each measurement round, with the latter realistically limited by the detection time jitter. Using an extractor composably secure against quantum adversary with quantum side information, we calculate an asymptotic rate of ≈1300 random bits/s. With an experimental run of 43 min, we generated 617 920 random bits, corresponding to ≈240 random bits/s.
- Published
- 2018
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189. Mothers' reproductive and medical history misinformation practices as strategies against healthcare providers' domination and humiliation in maternal care decision-making interactions: an ethnographic study in Southern Ghana.
- Author
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Yevoo LL, Agyepong IA, Gerrits T, and van Dijk H
- Subjects
- Anthropology, Cultural, Communication, Decision Making, Female, Ghana, Health Personnel, Humans, Medical History Taking statistics & numerical data, Mothers, Pregnancy, Attitude of Health Personnel ethnology, Health Behavior ethnology, Maternal Health Services statistics & numerical data, Patient Acceptance of Health Care ethnology, Professional-Patient Relations
- Abstract
Background: Pregnant women can misinform or withhold their reproductive and medical information from providers when they interact with them during care decision-making interactions, although, the information clients reveal or withhold while seeking care plays a critical role in the quality of care provided. This study explored 'how' and 'why' pregnant women in Ghana control their past obstetric and reproductive information as they interact with providers at their first antenatal visit, and how this influences providers' decision-making at the time and in subsequent care encounters., Methods: This research was a case-study of two public hospitals in southern Ghana, using participant observation, conversations, interviews and focus group discussions with antenatal, delivery, and post-natal clients and providers over a 22-month period. The Ghana Health Service Ethical Review Committee gave ethical approval for the study (Ethical approval number: GHS-ERC: 03/01/12). Data analysis was conducted according to grounded theory., Results: Many of the women in this study selectively controlled the reproductive, obstetric and social history information they shared with their provider at their first visit. They believed that telling a complete history might cause providers to verbally abuse them and they would be regarded in a negative light. Examples of the information controlled included concealing the actual number of children or self-induced abortions. The women adopted this behaviour as a resistance strategy to mitigate providers' disrespectful treatment through verbal abuses and questioning women's practices that contradicted providers' biomedical ideologies. Secondly, they utilised this strategy to evade public humiliation because of inadequate privacy in the hospitals. The withheld information affected quality of care decision-making and care provision processes and outcomes, since misinformed providers were unaware of particular women's risk profile., Conclusion: Many mothers in this study withhold or misinform providers about their obstetric, reproductive and social information as a way to avoid receiving disrespectful maternal care and protect their privacy. Improving provider client relationship skills, empowering clients and providing adequate infrastructure to ensure privacy and confidentiality in hospitals, are critical to the provision of respectful maternal care.
- Published
- 2018
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190. Short-wave infrared compressive imaging of single photons.
- Author
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Gerrits T, Lum DJ, Verma V, Howell J, Mirin RP, and Nam SW
- Abstract
We present a short-wave infrared (SWIR) single photon camera based on a single superconducting nanowire single photon detector (SNSPD) and compressive imaging. We show SWIR single photon imaging at a megapixel resolution with a low signal-to-background ratio around 0.6, show SWIR video acquisition at 20 frames per second and 64x64 pixel video resolution, and demonstrate sub-nanosecond resolution time-of-flight imaging. All scenes were sampled by detecting only a small number of photons for each compressive sampling matrix. In principle, our technique can be used for imaging faint objects in the mid-IR regime.
- Published
- 2018
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191. Reproductive Travel to Ghana: Testimonies, Transnational Relationships, and Stratified Reproduction.
- Author
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Gerrits T
- Subjects
- Adult, Anthropology, Medical, Female, Ghana ethnology, Humans, Internationality, Male, Middle Aged, Gestational Carriers, Tissue Donors, Medical Tourism, Reproductive Techniques, Assisted
- Abstract
In this article, I address reproductive travel to Ghana, based on research conducted in two private fertility clinics. Both clinics attract clients from West African countries as well as Ghanaian people living in the US and Europe. Their motivations to visit these clinics include positive "testimonies" about treatment results, "bioavailability" of matching donor material and surrogates, lower treatment costs and the circumvention of restricting regulations in the country of residence. Communication technologies are central in facilitating reproductive travel. Finally, I argue that the "international choreographies" of reproductive travel are co-shaped by the unique biographies and transnational relationships of the people involved.
- Published
- 2018
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192. Compressive characterization of telecom photon pairs in the spatial and spectral degrees of freedom.
- Author
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Montaut N, Magaña-Loaiza OS, Bartley TJ, Verma VB, Nam SW, Mirin RP, Silberhorn C, and Gerrits T
- Abstract
In the past few years, physicists and engineers have demonstrated the possibility of utilizing multiple degrees of freedom of the photon to perform information processing tasks for a wide variety of applications. Furthermore, complex states of light offer the possibility of encoding and processing many bits of information in a single photon. However, the challenges involved in the process of extracting large amounts of information, encoded in photonic states, impose practical limitations to realistic quantum technologies. Here, we demonstrate characterization of quantum correlated photon pairs in the spatial and spectral degrees of freedom. Our technique utilizes a series of random projective measurements in the spatial basis that do not perturb the spectral properties of the photon. The sparsity in the spatial properties of downconverted photons allows us to exploit the potential of compressive sensing to reduce the number of measurements to reconstruct spatial and spectral properties of correlated photon pairs at telecom wavelength. We demonstrate characterization of a photonic state with 12 × 10
9 dimensions using only 20% of the measurements with respect to the conventional raster scan technique. Our characterization technique opens the possibility of increasing and exploiting the complexity and dimensionality of quantum protocols that utilize multiple degrees of freedom of light with high efficiency.- Published
- 2018
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193. Identification of nonclassical properties of light with multiplexing layouts.
- Author
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Sperling J, Eckstein A, Clements WR, Moore M, Renema JJ, Kolthammer WS, Nam SW, Lita A, Gerrits T, Walmsley IA, Agarwal GS, and Vogel W
- Abstract
In Sperling et al. [Phys. Rev. Lett. 118 , 163602 (2017)], we introduced and applied a detector-independent method to uncover nonclassicality. Here, we extend those techniques and give more details on the performed analysis. We derive a general theory of the positive-operator-valued measure that describes multiplexing layouts with arbitrary detectors. From the resulting quantum version of a multinomial statistics, we infer nonclassicality probes based on a matrix of normally ordered moments. We discuss these criteria and apply the theory to our data which are measured with superconducting transition-edge sensors. Our experiment produces heralded multiphoton states from a parametric down-conversion light source. We show that the known notions of sub-Poisson and sub-binomial light can be deduced from our general approach, and we establish the concept of sub-multinomial light, which is shown to outperform the former two concepts of nonclassicality for our data.
- Published
- 2017
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194. Detector-Independent Verification of Quantum Light.
- Author
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Sperling J, Clements WR, Eckstein A, Moore M, Renema JJ, Kolthammer WS, Nam SW, Lita A, Gerrits T, Vogel W, Agarwal GS, and Walmsley IA
- Abstract
We introduce a method for the verification of nonclassical light which is independent of the complex interaction between the generated light and the material of the detectors. This is accomplished by means of a multiplexing arrangement. Its theoretical description yields that the coincidence statistics of this measurement layout is a mixture of multinomial distributions for any classical light field and any type of detector. This allows us to formulate bounds on the statistical properties of classical states. We apply our directly accessible method to heralded multiphoton states which are detected with a single multiplexing step only and two detectors, which are in our work superconducting transition-edge sensors. The nonclassicality of the generated light is verified and characterized through the violation of the classical bounds without the need for characterizing the used detectors.
- Published
- 2017
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195. Infertility in the Global South: Raising awareness and generating insights for policy and practice.
- Author
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Gerrits T, Van Rooij F, Esho T, Ndegwa W, Goossens J, Bilajbegovic A, Jansen A, Kioko B, Koppen L, Kemunto Migiro S, Mwenda S, and Bos H
- Abstract
Infertility is a highly prevalent reproductive health condition in the global South, which often has a devastating impact on the people concerned. Yet, thus far it hardly received any attention from policy makers, Non-Governmental Organizations (NGOs) or donors working in the field of Sexual and Reproductive Health and Rights (SRHR). For this reason we have set up a project to increase knowledge and awareness about infertility and childlessness among those stakeholders and organizations and to generate insight into (possible) interventions in this field. The project received a grant by Share-Net International (the Knowledge Platform in the field of SRHR, funded by the Dutch Ministry of Foreign Affairs) and is a unique collaboration between universities, fertility clinics, fertility support groups and the Walking Egg Foundation. The project consists of multimethods studies in Ghana and Kenya as well as dissemination workshops and meetings in these countries and the Netherlands. The first workshops in Kenya have already taken place with successful feedback from stakeholders. In this commentary we provide insight into the project and the main points and recommendations discussed in the Workshops in Kenya.
- Published
- 2017
196. The Role of Trust in CenteringPregnancy: Building Interpersonal Trust Relationships in Group-Based Prenatal Care in The Netherlands.
- Author
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Kweekel L, Gerrits T, Rijnders M, and Brown P
- Subjects
- Adult, Female, Humans, Interviews as Topic, Midwifery, Netherlands, Pregnancy, Qualitative Research, Young Adult, Interpersonal Relations, Prenatal Care methods, Social Support, Trust
- Abstract
Background: CenteringPregnancy (CP) is a specific model of group-based prenatal care for women, implemented in 44 midwifery practices in The Netherlands since 2011. Women have evaluated CP positively, especially in terms of social support, and improvements have been made in birthweight and preterm-birth outcomes; however, there is limited understanding as to why. The purpose of this study was to examine the mechanisms that create trusting relationships within CP to better understand CP outcomes and effectiveness., Methods: A qualitative study was conducted using in-depth interviews with 26 (former) CP participants, alongside observations of CP sessions. All interviews were transcribed and analyzed following open, axial, and selective coding., Results: Most women characterized trust as a positive expectation about how others would respond to sensitive information that was shared within the group. Trust emerged within the data as a multidimensional concept and several preconditions seemed crucial in building trusting relations: vulnerability, communication, reciprocity, chemistry, and atmosphere. The facilitating of interpersonal trust among CP participants enhanced group processes, especially as a basis for social support by which women said they were more eager to share sensitive information in a trusting environment., Conclusions: Processes of trust were interwoven within various CP group dynamics. Trust facilitated social support which in turn enabled reassurance and the building of women's self-confidence., (© 2016 Wiley Periodicals, Inc.)
- Published
- 2017
- Full Text
- View/download PDF
197. Quantum frequency bridge: high-accuracy characterization of a nearly-noiseless parametric frequency converter.
- Author
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Burenkov IA, Gerrits T, Lita A, Nam SW, Krister Shalm L, and Polyakov SV
- Abstract
We demonstrate an efficient and inherently ultra-low noise frequency conversion via a parametric sum frequency generation. Due to the wide separation between the input and pump frequencies and the low pump frequency relative to the input photons, the upconversion results in only ≈100 background photons per hour. To measure such a low rate, we introduced a dark count reduction algorithm for an optical transition edge sensor.
- Published
- 2017
- Full Text
- View/download PDF
198. Spectral correlation and interference in continuous-wave non-degenerate photon pairs at telecom wavelengths.
- Author
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Kuo PS, Gerrits T, Verma V, and Nam SW
- Abstract
We have developed an entangled photon pair source based on a domain-engineered, type-II periodically poled lithium niobate crystal that produces signal and idler photons at 1533 nm and 1567 nm. We characterized the spectral correlations of the generated entangled photons using fiber-assisted signal-photon spectroscopy. We observed interference between the two down-conversion paths after erasing polarization distinguishability of the down-converted photons. The observed interference signature is closely related to the spectral correlations between photons in a Hong- Ou-Mandel interferometer. These measurements suggest good indistinguishability between the two downconversion paths, which is required for high entanglement visibility.
- Published
- 2017
- Full Text
- View/download PDF
199. Glyphs for General Second-Order 2D and 3D Tensors.
- Author
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Gerrits T, Rossl C, and Theisel H
- Abstract
Glyphs are a powerful tool for visualizing second-order tensors in a variety of scientic data as they allow to encode physical behavior in geometric properties. Most existing techniques focus on symmetric tensors and exclude non-symmetric tensors where the eigenvectors can be non-orthogonal or complex. We present a new construction of 2d and 3d tensor glyphs based on piecewise rational curves and surfaces with the following properties: invariance to (a) isometries and (b) scaling, (c) direct encoding of all real eigenvalues and eigenvectors, (d) one-to-one relation between the tensors and glyphs, (e) glyph continuity under changing the tensor. We apply the glyphs to visualize the Jacobian matrix fields of a number of 2d and 3d vector fields.
- Published
- 2017
- Full Text
- View/download PDF
200. Perceptions of oocyte banking from women intending to circumvent age-related fertility decline.
- Author
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de Groot M, Dancet E, Repping S, Goddijn M, Stoop D, van der Veen F, and Gerrits T
- Subjects
- Adult, Biological Specimen Banks, Female, Humans, Infertility, Female etiology, Infertility, Female psychology, Qualitative Research, Aging psychology, Attitude to Health, Cryopreservation, Infertility, Female prevention & control, Oocytes, Parenting psychology, Reproductive Techniques, Assisted psychology
- Abstract
Introduction: Women can now opt to bank their oocytes with the intention of increasing their chances of achieving a pregnancy after their fertility has declined. This exploratory study aimed to gain insight into how women, considering oocyte banking to circumvent age-related fertility decline, perceive this intervention., Material and Methods: We conducted a qualitative study in a Dutch university medical center and held in-depth interviews with women on the waiting list for oocyte banking. We recorded the interviews, transcribed them verbatim and used thematic analysis., Results: All women were financially independent and lived in single-person urban households. They opted for oocyte banking because they wished to share parenthood with a future partner rather than becoming a single parent. This strong desire was key in their interpretation of all aspects of the intervention. Women set aside information about the limited success rates and potential risks, as they were optimistic about their own prognosis, thought that the chances for success were equally likely as the chances it would fail, and because of "anticipatory regret". They perceived oocyte banking as a "helping hand" to achieve shared parenthood. Although women found the costs of the intervention high, they were willing to invest their money to increase their chances for shared parenthood., Conclusions: Oocyte banking allows women to circumvent age-related fertility decline. The prospect of potential shared parenthood overrules the perceived health risks and burden. Health professionals should take this into account when informing potential users of oocyte banking., (© 2016 Nordic Federation of Societies of Obstetrics and Gynecology.)
- Published
- 2016
- Full Text
- View/download PDF
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