1,381 results on '"Martin, Robert A."'
Search Results
2. Unravelling the chloride dopant induced film improvement in all-inorganic perovskite absorbers.
- Author
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Nicholson, Stefan, Bruckbauer, Jochen, Edwards, Paul R., Trager-Cowan, Carol, Martin, Robert W., and Ivaturi, Aruna
- Abstract
CsPbI
2 Br perovskite material has been the focus of much recent research, thanks to its improved stability over CsPbI3 , useful bandgap of 1.9 eV and enhanced thermal stability over hybrid perovskite materials with volatile organic components. It has great potential for both single junction solar cells for indoor applications, and implementation in tandem cells. However, moisture stability has remained an issue. In order to overcome this roadblock towards commercialisation, metal chloride dopants have been widely investigated to improve film quality and reduce damage from humidity. Most of the studies report that the metal cation in the dopant plays a greater role in the improvement of the film properties than the chloride anions, which are thought to be removed during annealing in some studies. The majority of the research to date on this topic has focussed on investigating device performance and bulk film characteristics, with limited attention paid to grain-level crystallinity and whether the dopant is proportionally incorporated into the film. In the present work, cathodoluminescence (CL) and electron backscatter diffraction (EBSD) are utilised to investigate the effects of a lead chloride dopant, both on emission and crystal structure at a grain level, with the findings supported by X-ray diffraction (XRD). Confirmation of proportional incorporation of the dopant into the final prepared films is provided by wavelength dispersive X-ray (WDX) spectroscopy. This work provides valuable insight into the impact chloride dopants have on all-inorganic perovskite absorbers, helping to influence future dopant strategies. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
3. Tin Gallium Oxide Epilayers on Different Substrates: Optical and Compositional Analysis.
- Author
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Hunter, Daniel. A., Naresh‐Kumar, Gunasekar, Edwards, Paul R., Makydonska, Olha, Massabuau, Fabien C. P., Hatipoglu, Isa, Mukhopadhyay, Partha, Schoenfeld, Winston V., and Martin, Robert W.
- Subjects
MOLECULAR beam epitaxy ,LIGHT transmission ,OPTICAL measurements ,SUBSTRATES (Materials science) ,OPTICAL properties - Abstract
Electron beam techniques have been used to analyze the impact of substrate choice and growth parameters on the compositional and optical properties of tin gallium oxide [(SnxGa1−x)2O3] thin films grown by plasma‐assisted molecular beam epitaxy. Sn incorporation and film quality are found to be highly dependent on growth temperature and substrate material (silicon, sapphire, and bulk Ga2O3) with alloy concentrations varying up to an x value of 0.11. Room temperature cathodoluminescence spectra show the Sn alloying suppressing UV (3.3–3.0 eV), enhancing blue (2.8–2.4 eV), and generating green (2.4–2.0 eV) emission, indicative of the introduction of a high density of gallium vacancies (VGa) and subsequent VGa–Sn complexes. This behavior was further analyzed by mapping composition and luminescence across a cross section. Compared to Ga2O3, the spectral bands show a clear redshift due to bandgap reduction, confirmed by optical transmission measurements. The results show promise that the bandgap of gallium oxide can successfully be reduced through Sn alloying and used for bandgap engineering within UV optoelectronic devices. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
4. Surrogate gradient methods for data-driven foundry energy consumption optimization.
- Author
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Chen, Shikun, Kaufmann, Tim, and Martin, Robert J.
- Subjects
MACHINE learning ,MANUFACTURING processes ,METAL castings ,RANDOM forest algorithms ,CONSTRAINED optimization ,KRIGING - Abstract
In many industrial applications, data-driven models are more and more commonly employed as an alternative to classical analytical descriptions or simulations. In particular, such models are often used to predict the outcome of an industrial process with respect to specific quality characteristics from both observed process parameters and control variables. A major step in proceeding from purely predictive to prescriptive analytics, i.e., towards leveraging data-driven models for process optimization, consists of, for given process parameters, determining control variable values such that the output quality improves according to the process model. This task naturally leads to a constrained optimization problem for data-driven prediction algorithms. In many cases, however, the best available models suffer from a lack of regularity: methods such as gradient boosting or random forests are generally non-differentiable and might even exhibit discontinuities. The optimization of these models would therefore require the use of derivative-free techniques. Here, we discuss the use of alternative, independently trained differentiable machine learning models as a surrogate during the optimization procedure. While these alternatives are generally less accurate representations of the actual process, the possibility of employing derivative-based optimization methods provides major advantages in terms of computational performance. Using classical benchmarks as well as a real-world dataset obtained from an industrial environment, we demonstrate that these advantages can outweigh the additional model error, especially in real-time applications. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
5. Observations of phosphorus-bearing molecules in the interstellar medium.
- Author
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Fontani, Francesco, Stewart McCoustra, Martin Robert, Rimola, Albert, and Guillemin, Jean-Claude
- Subjects
INTERSTELLAR molecules ,INTERSTELLAR medium ,COMPUTATIONAL chemistry ,ASTROCHEMISTRY ,COSMOCHEMISTRY ,PHOSPHORUS compounds - Abstract
The chemistry of phosphorus (
31 P) in space is particularly significant due to the key role it plays in biochemistry on Earth. Utilising radio and infrared spectroscopic observations, several key phosphorus-containing molecules have been detected in interstellar clouds, circumstellar shells, and even extragalactic sources. Among these, phosphorus nitride (PN) was the first P-bearing molecule detected in space, and still is the species detected in the largest number of sources. Phosphorus oxide (PO) and phosphine (PH3 ) were also crucial species due to their role both in chemical networks and in forming biogenic compounds. The still limited high-angular resolution observations performed so far are shading light on the geometrical distribution of these molecules, which represent crucial insights on their formation processes. Observations have also highlighted the challenges and complexities associated with detecting and understanding phosphorus chemistry in space, owing to the low elemental abundance of P relative to other elements. This review article provides a state-of-art picture of the observational results obtained so far on phosphorus compounds in the interstellar medium. Special attention is given to star- forming regions, and to their implications for our understanding of prebiotic chemistry and the potential for life beyond Earth. Our knowledge of the dominant formation and destruction pathways of the most abundant species has improved, but critical questions remain open, among which: what is (are) the main phosphorus carrier(s) in space? Upcoming new facilities are expected to contribute significantly to this field, offering opportunities to both detect new phosphorus-bearing molecules and enlarge the number of sources in which the chemistry of P can be studied. The synergy between observations, theoretical models, laboratory experiments, and computational chemistry is mandatory to significantly progress in our comprehension of the chemistry of this important but poorly studied chemical element. [ABSTRACT FROM AUTHOR]- Published
- 2024
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- View/download PDF
6. Adaptation constraints and prospects for future research priorities in lowland rice-based farming systems: learning experiences from Northwest Cambodia.
- Author
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Touch, Van, Cross, Rebecca, Grünbühel, Clemens, Van Ogtrop, Floris, Ampt, Peter, Yorn, Try, Martin, Robert John, Cook, Brian R., and Tan, Daniel K. Y.
- Subjects
AGRICULTURAL technology ,FARM management ,SUSTAINABLE agriculture ,AGRICULTURE ,RICE farming ,COVER crops - Abstract
Sustainable agricultural development not only addresses global food insecurity but may also alleviate poverty by enriching the lives of millions of smallholder farmers. Improving the sustainability and profitability of agriculture where smallholders are dominant creates profound impacts because small landholding farmers produce approximately 70–80% of the global food. The need for a thorough understanding of the factors affecting farmers' adoption of agricultural technologies and practices has been identified from extant literature as an important research gap. Responding to the research gap and need, this study examined the challenges that prevent farm households from adopting improved farming practices and/or technologies in Banteay Meanchey and Battambang provinces in Northwest Cambodia. A total of 524 rice producing farm household representatives were randomly selected from a household database maintained by the local government authorities. A mixed methods approach was used in the study including semi-structured interviews followed by in-depth interviews, field observations, and literature review. Farmers were found to be confronted with a range of challenges and concerns, including soil degradation, weeds, diseases, insect pests, high production costs, flooding, droughts, changing rainfall pattern, and unreliable rainfall distribution. The research findings demonstrate that improved crop production practices (e.g., adopting mechanised direct seeding methods of crop establishment, maintaining and improving soil health through crop residue retention, growing cover crops, etc.) and better resource use efficiency (e.g., reducing seeding rates to less than 100 kg/ha, being more strategic in the use of integrated nutrient, weed, and pest management strategies, etc.) can be a starting point for sustainable intensification of rice production. This transition towards intensifying paddy production sustainably may become even more effective through a clear understanding of local contexts, farm household characteristics, available resources, and the farm management practices and constraints. We observed that farmers and their associations have yet to be fully recognised as partners and actors in Cambodia. Instead, they tend to be viewed as beneficiaries and recipients of improved practices and technologies. We, therefore, propose that farmers and their associations be acknowledged and included in a process of co-creation of knowledge-practices. Such partnerships will enable the inclusion of factors (e.g., production costs, production risks, complexity and practicability of implementations, product market and prices, etc.) shown to influence farmers' adoption of innovative farming practices and technologies. The original contribution of this article is a real-world account of the constraints and limitations experienced by smallholder rice farmers in Cambodia, which are connected to future research and development priorities in the region. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
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7. Ensquared Energy and Optical Centroid Efficiency in Optical Sensors: Part 2, Primary Aberrations.
- Author
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Strojnik, Marija, Martin, Robert, and Wang, Yaujen
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OPTICAL aberrations ,OPTICAL devices ,OPTICAL sensors ,ASTIGMATISM ,CENTROID ,ASTIGMATISM (Optics) - Abstract
We previously proposed that the optical centroid efficiency (OCE) might be a preferred figure-of-merit to the enclosed energy of a rectangular pixel (EOD) for an instrument subject to unpredictable environmental jitter and alignment conditions. Here we follow the same symbols for the corresponding quantities, particularly the width of the pixel as being equal to 2d. Here we analyze the performance of the OCE vs. the EOD for the three Seidel primary aberrations of an optical component: spherical, coma, and astigmatism, plus defocus. We show that the OCE has an approximate U-shape when graphed against the EOD, for the aberrations ranging from 0 to 1.25λ. We conclude that for pixels larger than 2d = 3λF/#, a small pixel will feature better performance when expecting jitter, misalignment, and other environmental and unpredictable conditions. When evaluating the performance of low-aberration instruments in dynamic and unpredictable environments, the choice of the lager pixel 2d = 7λF/# might be advantageous. Its selection will result in the deterioration of image resolution. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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- View/download PDF
8. Barriers to resection following neoadjuvant chemotherapy for resectable pancreatic adenocarcinoma: A national and local perspective.
- Author
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Fromer, Marc W., Mouw, Tyler J., Scoggins, Charles R., Egger, Michael E., Philips, Prejesh, McMasters, Kelly M., and Martin, Robert C. G.
- Published
- 2024
- Full Text
- View/download PDF
9. On the correlation between the enantiomeric excess of L-isovaline and the level of aqueous alteration in carbonaceous meteorites.
- Author
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Avnir, David, McCoustra, Martin Robert Stewart, and Dworkin, Jason P.
- Subjects
CIRCULAR dichroism ,METEORITES ,PARALLEL processing - Abstract
A positive correlation was observed between the enantiomeric excess (ee) of L-isovaline (L-iVal) and the degree of aqueous alteration (AqA) of carbonaceous meteorites. The origin of this remarkable phenomenon has remained enigmatic from two points of view: First, the correlation is between seemingly unrelated observables-nothing about AqA is of chiral characteristics; and second, following the accepted assumption that circularly polarized light (CPL) was the origin of the observed meteoritic ee of L-amino acids (AAs), it remined unclear why some of the observed levels of the ee of L-iVal in that correlation are significantly higher than those observed in laboratory simulations or those obtained from circular dichroism (CD) g-factor calculations. The current proposition accounting for this picture attributes late AqA conditions of the meteoritic parent bodies as providing the grounds for amplification of early initially CPL-generated low levels of L-ee. For reasons summarized below, this interpretation, which treats the CPL event and the AqA process as occurring in wide-time separated eras, is re-visited. An alternative interpretation of the observed correlation and of the high ee-values, is provided. It focuses on hydrophilic dust-aggregates clouds in wet star-forming regions in early presolar times, where both the CPL event and the grounds leading to the later AqA processes of the parent bodies, occurred. This mechanism removes the time separation between the initial ee formation and the AqA of the parent body, and replaces it with parallel processes, providing a scenario to the observation of high ee's without total destruction, and to the apparent AqA/L-ee correlation. Although iVal is at the focus of this report, the steps of the development of the alternative mechanism and the conclusions that arise from it, are relevant and applicable to the general observations of L-ee's of meteoritic AA's. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
10. Barriers to resection following neoadjuvant chemotherapy for resectable pancreatic adenocarcinoma: A national and local perspective.
- Author
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Fromer, Marc W., Mouw, Tyler J., Scoggins, Charles R., Egger, Michael E., Philips, Prejesh, McMasters, Kelly M., and Martin, Robert C. G.
- Published
- 2024
- Full Text
- View/download PDF
11. Combining Cathodoluminescence Hyperspectral Imaging with Other Electron Microscopy Modes to Study Semiconducting Materials for Ultraviolet Applications.
- Author
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Edwards, Paul R, Cameron, Douglas, Hunter, Daniel A, Naresh-Kumar, G, and Martin, Robert W
- Published
- 2024
- Full Text
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12. Cleavelandite: Only Crystals Small and Beautiful.
- Author
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Martin, Robert F.
- Subjects
GEMS & precious stones ,MUSCOVITE ,MINERALS ,CARBONATE minerals ,CRYSTALS ,QUARTZ ,GARNET - Abstract
The text discusses the formation and characteristics of cleavelandite, a type of albite mineral found in granitic pegmatites. It explains that cleavelandite forms in cavities after the magma solidifies and that the presence of certain minerals and conditions in the pocket environment contribute to its formation. The text also discusses the differences in cleavelandite formation in LCT and NYF pegmatites, which are different types of granitic pegmatites. Dr. Robert F. Martin explores the formation and characteristics of cleavelandite, proposing that it forms through repeated nucleation in a supercritical fluid phase that is supersaturated with albite, with growth surfaces being poisoned by a nanolayer of phyllosilicate. The presence of cleavelandite in pegmatites indicates a shallow depth and the presence of cavities. Dr. Martin's research contributes to a better understanding of the genesis of cleavelandite and the nature of pegmatite formation. [Extracted from the article]
- Published
- 2024
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13. A distributional approach to U.S. personal consumption expenditures: an overview.
- Author
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Garner, Thesia I., Martin, Robert, Matsumoto, Brett, and Curtin, Scott
- Subjects
CONSUMPTION (Economics) ,CONSUMER surveys ,NONPROFIT organizations ,ACQUISITION of data - Abstract
We distribute Personal Consumption Expenditures (PCE) across households in the U.S. using microdata from the Consumer Expenditure Surveys (CE) for the period 2017–2021. Since the CE mainly collects data on out-of-pocket spending, we supplement it with imputations based on other survey and administrative data to better match PCE definitions, particularly with respect to health care. Over the study period, out of the total PCE (excluding expenditures by non-profits serving households), the bottom 20% accounted for between 8.4% and 9.5%, while the top 20% accounted for 39.4–41.6%. The 90/10 ratio for equivalized PCE ranged from 3.3 to 3.7, and the Gini coefficient from 0.31 to 0.33. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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- View/download PDF
14. The Tepsi Ultrabasic Intrusion, the Northern Part of the Lapland–Belomorian Belt, Kola Peninsula, Russia.
- Author
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Barkov, Andrei Y., Nikiforov, Andrey A., Martin, Robert F., Silyanov, Sergey A., and Lobastov, Boris M.
- Subjects
MINERALS ,ULTRABASIC rocks ,SCHEELITE ,PLAGIOCLASE ,SERPENTINITE ,APATITE - Abstract
The Tepsi ultrabasic body is located in the northeastern Fennoscandian Shield close to the junction of the Serpentinite Belt–Tulppio Belt (SB–TB) with suites of the Lapland–Belomorian Belt (LBB) of Paleoproterozoic age. The body is a deformed laccolith that has tectonic contacts with Archean rocks. Its primary textures and magmatic parageneses are widely preserved. Fine-grained olivine varies continuously from Fo
90.5 to Fo65.4 . The whole-rock variations in MgO, Fe2 O3 , SiO2 , and other geochemical data are also indicative of a significant extent of differentiation. Compositional variations were examined in the grains of calcic and Mg-Fe amphiboles, clinochlore, micas, plagioclase, members of the chromite–magnetite series, ilmenite, apatite, pentlandite, and a number of other minor mineral species. Low-sulfide disseminated Ni-Cu-Co mineralization occurred sporadically, with the presence of species enriched in As or Bi, submicrometric grains rich in Pt and Ir, or diffuse zones in pentlandite enriched in (Pd + Bi). We recognize two series: the pentlandite series (up to 2.5–3 wt.% Co) and the cobaltpentlandite series (~1 to ~8 apfu Co). The latter accompanied serpentinization. The two series display differences in their substitutions: Ni ↔ Fe and Co → (Ni + Fe), respectively. Relative enrichments in H2 O, Cl, and F, observed in grains of apatite (plus high contents of Cl in hibbingite or parahibbingite), point to the abundance of volatiles accumulated during differentiation. We provide the first documentation of scheelite grains in ultrabasic rocks, found in evolved olivine-rich rocks (Fo77–72 ). We also describe unusual occurrences of hypermagnesian clinopyroxene associated with tremolite and serpentine. Abundant clusters of crystallites of diopside display a microspinifex texture. They likely predated serpentinization and formed owning to rapid crystallization in a differentiated portion of a supercooled oxidized melt or, less likely, fluid, after bulk crystallization of the olivine. We infer that the laccolithic Tepsi body crystallized rapidly, in a shallow setting, and could thus not form megacycles in a layered series or produce a well-organized structure. Our findings point to the existence of elevated PGE-Au-Ag potential in numerous ultrabasic–basic complexes of the SB–TB–LBB megastructure. [ABSTRACT FROM AUTHOR]- Published
- 2024
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15. Childcare needs as a barrier to healthcare among women in a safety-net health system.
- Author
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Gaur, Priyanka, Ganguly, Anisha P., Kuo, Madyson, Martin, Robert, Alvarez, Kristin S., Bhavan, Kavita P., and Kho, Kimberly A.
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SAFETY-net health care providers ,WOMEN'S health ,SOCIAL determinants of health ,CHILD care ,HISPANIC American women ,CONVENIENCE sampling (Statistics) - Abstract
Background: Childcare needs are an understudied social determinant of health. The effect of childcare needs on access to healthcare must be understood to inform health system interventions and policy reform. This study sought to characterize childcare needs, access to childcare, and prior experience with navigating childcare needs in healthcare settings among women in a safety-net population. Methods: We conducted a cross-sectional study of patient-reported survey data collected in-person between April and October 2019. Surveys were administered in waiting rooms of ambulatory services in a large, urban safety-net health system in Dallas, Texas. Survey respondents were derived from a random convenience sample of women waiting for outpatient appointments. Participants were screened for having children under the age of 13 and/or childcare responsibilities for inclusion in the sample. Outcomes of interest included self-reported delayed or missed care, reasons for delayed or missed care, perceived difficulty in accessing childcare, prior methods for managing childcare during healthcare appointments, and prior experience with childcare centers. Results: Among the 336 respondents (96.7% response rate), 121 (36.0%) reported delaying or missing a mean 3.7 appointments/year. Among women with delayed or missed care, 54.5% reported childcare barriers as the primary reason for deferral of care, greater than transportation (33%) or insurance (25%) barriers. Respondents rated childcare access as more difficult than healthcare access. Delayed or missed care due to childcare was more common among White (68.8%) and Black (55.0%) women compared to Hispanic women (34.3%). Common methods of navigating childcare needs during scheduled appointments included bringing children to appointments (69.1%) and re-scheduling or missing the scheduled appointment (43.0%). 40.6% of patients reported leaving an appointment before completion due to childcare needs. Conclusions: Childcare needs are a leading barrier to healthcare among women accessing care in safety-net settings. Unmet childcare needs result in deferral of care, which may impact health outcomes. Childcare access is perceived as more challenging than healthcare access itself. Health system and policy interventions are needed to address childcare as a social determinant of health. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
16. Technique Variation in the Surgical Treatment of Lateral Ankle Instability.
- Author
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Wilke, Aaron J., Martin, Robert, Bates, Nathaniel A., Jastifer, James R., and Martin, Kevin D.
- Abstract
Introduction. Lateral ankle sprains are the most common type of injury to the ankle and can lead to ankle instability. There are many described techniques for the surgical treatment of lateral ankle instability. The purpose of this study is to quantify the variation in surgeon technique for lateral ankle instability treatment. Methods. Surveys were sent to 62 orthopaedic foot and ankle surgeons regarding surgical technique for the treatment of lateral ankle instability. Clinical agreement was defined as greater than 80% agreement to assess the cohesiveness of surgical methods as described by Marx et al. Results. Response rate was 49/62 (79%). There was clinical agreement for not using bone tunnels and not using metal anchors. All other factors lacked clinical agreement. A greater average number of throws and knots (4.2 for each, range 1-6 throws, range 2-12 knots) were used by surgeons that do not believe knots cause pain compared to an average of 3.9 (range, 1-6) throws and 4.0 (range, 2-15) knots by surgeons who do believe knots cause pain. The association that surgeon who believed knots do cause pain and thus used fewer knots and throws was not statistically significant (P >.05). The preferred material by surgeons in our study are as follows: nonabsorbable braided suture (26/49, 53%), suture tape (15/49, 31%), and fiber tape (4/49, 8%). Among surgeons who use absorbable suture (34/49, 69%), there was no significant difference (P >.05) between surgeons who believe knots cause pain (23/34, 68%) and those who do not (11/34, 32%). Discussion and Conclusion. Among this small sample of orthopaedic foot and ankle surgeons, there is wide variation in surgical technique for lateral ankle instability treatment and little agreement on the clinical standard of care. This disagreement highlights the need for comparative outcome studies in the treatment of ankle instability. Level of Evidence: Level III: Retrospective cohort study [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
17. Biotinylated Photocleavable Semiconductor Colloidal Quantum Dot Supraparticle Microlaser.
- Author
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Eling, Charlotte J., Bruce, Natalie, Gunasekar, Naresh-Kumar, Alves, Pedro Urbano, Edwards, Paul R., Martin, Robert W., and Laurand, Nicolas
- Abstract
Luminescent supraparticles of colloidal semiconductor nanocrystals can act as microscopic lasers and are hugely attractive for biosensing, imaging, and drug delivery. However, biointerfacing these to increase functionality while retaining their main optical properties remains an unresolved challenge. Here, we propose and demonstrate red-emitting, silica-coated CdS
x Se1−x /ZnS colloidal quantum dot supraparticles functionalized with a biotinylated photocleavable ligand. The success of each step of the synthesis is confirmed by scanning electron microscopy, energy dispersive X-ray and Fourier transform infrared spectroscopy, ζ-potential, and optical pumping measurements. The capture and release functionality of the supraparticle system is proven by binding to a neutravidin functionalized glass slide and subsequently cleaving off after UV-A irradiation. The biotinylated supraparticles still function as microlasers; e.g., a 9 μm diameter supraparticle has oscillating modes around 625 nm at a threshold of 58 mJ/cm2 . This work is a first step toward using supraparticle lasers as enhanced labels for bionano applications. [ABSTRACT FROM AUTHOR]- Published
- 2024
- Full Text
- View/download PDF
18. Cyclopropenimine‐Mediated CO2 Activation for the Synthesis of Polyurethanes and Small‐Molecule Carbonates and Carbamates.
- Author
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Wu, Dino, Martin, Robert T., Piña, Jeanette, Kwon, Junho, Crockett, Michael P., Thomas, Andy A., Gutierrez, Osvaldo, Park, Nathaniel H., Hedrick, James L., and Campos, Luis M.
- Subjects
ATMOSPHERIC carbon dioxide ,CARBAMATES ,POLYURETHANES ,CARBAMATE derivatives ,CARBON dioxide ,POLYMERS ,CARBONATES - Abstract
Carbon dioxide (CO2) is an abundant C1 feedstock with tremendous potential to produce versatile building blocks in synthetic applications. Given the adverse impact of CO2 on the atmosphere, it is of paramount importance to devise strategies for upcycling it into useful materials, such as polymers and fine chemicals. To activate such stable molecule, superbases offer viable modes of binding to CO2. In this study, a superbase cyclopropenimine derivative was found to exhibit exceptional proficiency in activating CO2 and mediating its polymerization at ambient temperature and pressure for the synthesis of polyurethanes. The versatility of this reaction can be extended to monofunctional amines and alcohols, yielding a variety of functional carbonates and carbamates. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
19. Cyclopropenimine‐Mediated CO2 Activation for the Synthesis of Polyurethanes and Small‐Molecule Carbonates and Carbamates.
- Author
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Wu, Dino, Martin, Robert T., Piña, Jeanette, Kwon, Junho, Crockett, Michael P., Thomas, Andy A., Gutierrez, Osvaldo, Park, Nathaniel H., Hedrick, James L., and Campos, Luis M.
- Subjects
ATMOSPHERIC carbon dioxide ,CARBAMATES ,POLYURETHANES ,CARBAMATE derivatives ,CARBON dioxide ,POLYMERS ,CARBONATES - Abstract
Carbon dioxide (CO2) is an abundant C1 feedstock with tremendous potential to produce versatile building blocks in synthetic applications. Given the adverse impact of CO2 on the atmosphere, it is of paramount importance to devise strategies for upcycling it into useful materials, such as polymers and fine chemicals. To activate such stable molecule, superbases offer viable modes of binding to CO2. In this study, a superbase cyclopropenimine derivative was found to exhibit exceptional proficiency in activating CO2 and mediating its polymerization at ambient temperature and pressure for the synthesis of polyurethanes. The versatility of this reaction can be extended to monofunctional amines and alcohols, yielding a variety of functional carbonates and carbamates. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
20. Rational Cuntz states peak on the free disk algebra.
- Author
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Martin, Robert T. W. and Shamovich, Eli
- Subjects
ALGEBRA ,HARDY spaces ,FOCK spaces ,POWER series - Abstract
We apply realization theory of noncommutative (NC) rational multipliers of the Fock space, or free Hardy space of square–summable power series in several noncommuting variables to the convex analysis of states on the Cuntz algebra. We show, in particular, that a large class of Cuntz states that arise as the "NC Clark measures" of isometric NC rational multipliers are peak states for Popescu's free disk algebra in the sense of Clouâtre and Thompson. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
21. Complete genome sequence of vaccinium-associated virus C, a new member of the family Totiviridae from Vaccinium floribundum.
- Author
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Alvarez-Quinto, Robert, Grinstead, Samuel, Kinard, Gary, Martin, Robert, and Mollov, Dimitre
- Abstract
Blueberries (Vaccinium sp.) are a major crop grown in the Pacific Northwest region. Currently, there are at least 17 known viruses that infect blueberry plants, and some of them cause a wide range of symptoms and economic losses. A new virus, vaccinium-associated virus C (VaVC) (family Totiviridae, genus Totivirus) was identified in an imported blueberry accession from the USDA-ARS National Clonal Germplasm Repository in Corvallis, Oregon. The complete genomic sequence of VaVC was determined, but the biological significance of VaVC is unknown and requires further study. Additional Vaccinium sp. accessions should be screened to investigate the incidence of this new virus. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
22. Alcohol-alcohol cross-coupling enabled by SH2 radical sorting.
- Author
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Ruizhe Chen, Intermaggio, Nicholas E., Jiaxin Xie, Rossi-Ashton, James A., Gould, Colin A., Martin, Robert T., Alcázar, Jesús, and MacMillan, David W. C.
- Published
- 2024
- Full Text
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23. Eliminating the benzos: A benzodiazepine-sparing approach to preventing and treating alcohol withdrawal syndrome.
- Author
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McCullough, Mary Alyce, Miller III, Preston R., Martin, Tamriage, Rebo, Kristin A., Stettler, Gregory R., Martin, Robert Shayn, Cantley, Morgan, Shilling, Elizabeth H., Hoth, James J., and Nunn, Andrew M.
- Published
- 2024
- Full Text
- View/download PDF
24. Cathodoluminescence and Friends to Study Defects in UV Emitters.
- Author
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Cameron, Douglas, Schilling, Marcel, Kusch, Gunnar, Edwards, Paul R, Spulis, Viesturs, Wernicke, Tim, Kneissl, Michael, Oliver, Rachel A, and Martin, Robert W
- Published
- 2024
- Full Text
- View/download PDF
25. Selective 1,2‐Hydroarylation(Alkenylation) of gem‐Difluoroalkenes to Access (−CF2H) Motifs.
- Author
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Lin, Leroy Qi Hao, Rentería‐Gómez, Ángel, Martin, Robert T., Zhang, Ying‐Qi, Ong, Kelvin Zhi Wei, Parris, Adam B., Gutierrez, Osvaldo, and Koh, Ming Joo
- Subjects
ALKENYLATION ,COUPLING reactions (Chemistry) ,ALKENES ,HYDRIDES - Abstract
An emerging class of C−C coupling transformations that furnish drug‐like building blocks involves catalytic hydrocarbonation of alkenes. However, despite notable advances in the field, hydrocarbon addition to gem‐difluoroalkenes without additional electronic activation remains largely unsuccessful. This owes partly to poor reactivity and the propensity of difluoroalkenes to undergo defluorinative side reactions. Here, we report a nickel catalytic system that promotes efficient 1,2‐selective hydroarylation and hydroalkenylation, suppressing defluorination and providing straightforward access to a diverse assortment of prized organofluorides bearing difluoromethyl‐substituted carbon centers. In contrast to radical‐based pathways and reactions triggered by hydrometallation via a nickel‐hydride complex, our experimental and computational studies support a mechanism in which a catalytically active nickel‐bromide species promotes selective carbonickelation with difluoroalkenes followed by alkoxide exchange and hydride transfer, effectively overcoming the difluoroalkene's intrinsic electronic bias. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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26. Selective 1,2‐Hydroarylation(Alkenylation) of gem‐Difluoroalkenes to Access (−CF2H) Motifs.
- Author
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Lin, Leroy Qi Hao, Rentería‐Gómez, Ángel, Martin, Robert T., Zhang, Ying‐Qi, Ong, Kelvin Zhi Wei, Parris, Adam B., Gutierrez, Osvaldo, and Koh, Ming Joo
- Subjects
ALKENYLATION ,COUPLING reactions (Chemistry) ,ALKENES ,HYDRIDES - Abstract
An emerging class of C−C coupling transformations that furnish drug‐like building blocks involves catalytic hydrocarbonation of alkenes. However, despite notable advances in the field, hydrocarbon addition to gem‐difluoroalkenes without additional electronic activation remains largely unsuccessful. This owes partly to poor reactivity and the propensity of difluoroalkenes to undergo defluorinative side reactions. Here, we report a nickel catalytic system that promotes efficient 1,2‐selective hydroarylation and hydroalkenylation, suppressing defluorination and providing straightforward access to a diverse assortment of prized organofluorides bearing difluoromethyl‐substituted carbon centers. In contrast to radical‐based pathways and reactions triggered by hydrometallation via a nickel‐hydride complex, our experimental and computational studies support a mechanism in which a catalytically active nickel‐bromide species promotes selective carbonickelation with difluoroalkenes followed by alkoxide exchange and hydride transfer, effectively overcoming the difluoroalkene's intrinsic electronic bias. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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27. Navigating the Healthcare Conundrum: Leadership Perspective from a Premier Healthcare Organization in Loma Linda's Blue Zone.
- Author
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Tan, Laren D, Hilliard, Anthony A, Peverini, Ricardo L, Martin, Robert D, Thomas, Tamara L, Wright, Trevor G, Edwards, Lyndon C, Lalas, Angela M, Staples-Evans, Helen M, Sharp, Barbara J, Ahn-Kim, Stella L, Hansen, Kent A, and Hart, Richard H
- Subjects
COST control ,HEALTH facility administration ,HEALTH insurance reimbursement ,MEDICAL care ,LEADERSHIP ,MEDICARE ,HOSPITALS ,PRIVATE sector ,PATIENT-centered care ,HEALTH services administrators ,ATTITUDES of medical personnel ,SUSTAINABLE development ,HEALTH facilities ,DRUGS ,MEDICAID ,HOSPITAL costs - Abstract
Navigating the healthcare conundrum in the Blue Zone of Loma Linda, California, requires understanding the unique factors that make this region stand out in terms of health and longevity. But more important is understanding the healthcare system sustaining the Blue Zone in Loma Linda, California. In an era marked by soaring healthcare costs and diminishing reimbursement rates, hospitals and physicians face an unprecedented challenge: providing excellent patient care while maintaining financial sustainability. This leadership perspective publication paper delves into the multifaceted struggles encountered by healthcare and hospital leaders, exploring the root causes, implications, and potential solutions for this complex issue. As we examine the evolving healthcare landscape, we aim to shed light on the critical need for innovative approaches to sustain the future of healthcare excellence in one of the five original Blue Zones. [ABSTRACT FROM AUTHOR]
- Published
- 2024
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- View/download PDF
28. Perinatal Outcomes among Women Identified by a Community Health Needs Assessment.
- Author
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Duryea, Elaine L., Martin, Robert, McIntire, Donald, Spong, Catherine Y., and Nelson, David B.
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MATERNAL health services ,INTENSIVE care units ,EVALUATION of human services programs ,CONFIDENCE intervals ,HEALTH services accessibility ,AGE distribution ,COMMUNITY health services ,RETROSPECTIVE studies ,PATIENTS ,PREGNANCY outcomes ,T-test (Statistics) ,PREECLAMPSIA ,PERINATAL death ,MEDICAL care use ,HOSPITAL admission & discharge ,DESCRIPTIVE statistics ,CHI-squared test ,NEEDS assessment ,LOGISTIC regression analysis ,ODDS ratio ,BODY mass index ,HEALTH equity ,MEDICAL needs assessment ,LONGITUDINAL method ,PREMATURE labor - Abstract
Objective The aim of the study is to compare perinatal outcomes for women with greater social needs, as identified by the Community Health Needs Assessment, to those of women living in other areas of the county. Study Design This was a retrospective cohort study of pregnant women delivering at a large inner-city county hospital. Perinatal outcomes were analyzed for women living within a target area with substantial health disparities and social needs, and compared with those women living outside the target area. Statistical analysis included student's t -test, Chi square, and logistic regression. Results Between January 2015 and July 2020, 66,936 women delivered at Parkland hospital. Of these, 7,585 (11%) resided within the target area. These women were younger (26.8 ± 6.5 vs. 27.9 ± 6.4 years, p < 0.001), more likely to be black (37 vs. 13%, p < 0.001), and had a higher body mass index or BMI (33.3 ± 7.0 vs. 32.6 ± 6.4 kg/m
2 , p < 0.001). All women were likely to access prenatal care, with 7,320 (96.5%) in the target area and 57,677 (97.2%) outside the area attending at least one visit. Adverse perinatal outcomes were increased for women living within the target area, which persisted after adjustment for age, race, and BMI. This included an increased risk of preeclampsia (adjusted risk ratio [aRR] 1.1, 95% confidence interval or CI [1.03, 1.2]) and abruption (aRR 1.3, 95% CI [1.1, 1.7]), as well as preterm birth before both 34 weeks (aRR 1.3, 95% CI [1.2, 1.5]) and 28 weeks (aRR 1.3, 95% CI [1.02,1.7]). It follows that neonatal ICU admission (aRR 2.1, 95% CI [1.3, 3.4]) and neonatal death (aRR 1.2, 95% CI [1.1, 1.3]) were increased within the target area. Interestingly, rate of postpartum visit attendance was higher in the target area (57 vs. 48%), p < 0.001. Conclusion Even among vulnerable populations, women in areas with worse health disparities and social needs are at greater risk of adverse perinatal outcomes. Efforts to achieve health equity will need to address social disparities. Key Points At a county hospital, 97% of women accessed prenatal care. Greater social needs were associated with adverse perinatal outcomes. Differences persisted with adjustment for age, race, and BMI. [ABSTRACT FROM AUTHOR]- Published
- 2024
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29. Adaptive changes in the DNA damage response during skeletal muscle cell differentiation.
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Faleiro, Inês, Afonso, Ana I., Balsinha, André, Lucas, Beatriz, Martin, Robert M., Gomes, Edgar R., and de Almeida, Sérgio F.
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DNA repair ,SKELETAL muscle ,CELL differentiation ,MUSCLE cells ,DOUBLE-strand DNA breaks ,MUSCULAR hypertrophy - Abstract
DNA double-strand breaks (DSBs) trigger specialized cellular mechanisms that collectively form the DNA damage response (DDR). In proliferating cells, the DDR serves the function of mending DNA breaks and satisfying the cell-cycle checkpoints. Distinct goals exist in differentiated cells that are postmitotic and do not face cell-cycle checkpoints. Nonetheless, the distinctive requirements and mechanistic details of the DDR in differentiated cells are still poorly understood. In this study, we set an in vitro differentiation model of human skeletal muscle myoblasts into multinucleated myotubes that allowed monitoring DDR dynamics during cell differentiation. Our results demonstrate that myotubes have a prolonged DDR, which is nonetheless competent to repair DSBs and render them significantly more resistant to cell death than their progenitors. Using live-cell microscopy and single-molecule kinetic measurements of transcriptional activity, we observed that myotubes respond to DNA damage by rapidly and transiently suppressing global gene expression and rewiring the epigenetic landscape of the damaged nucleus. Our findings provide novel insights into the DDR dynamics during cellular differentiation and shed light on the strategy employed by human skeletal muscle to preserve the integrity of the genetic information and sustain long-term organ function after DNA damage. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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- View/download PDF
30. Correlation between deep-level defects and functional properties of β-(SnxGa1-x)2O3 on Si photodetectors.
- Author
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Hatipoglu, Isa, Hunter, Daniel A., Mukhopadhyay, Partha, Williams, Martin S., Edwards, Paul R., Martin, Robert W., Schoenfeld, Winston V., and Naresh-Kumar, G.
- Subjects
CATHODOLUMINESCENCE ,WAVELENGTH dispersive X-ray spectroscopy ,PHOTODETECTORS ,MOLECULAR beam epitaxy ,ELECTRON microscope techniques ,TIN - Abstract
Heterogeneous integration of β-(Sn
x Ga1−x )2 O3 (TGO) UV-C photodetectors on silicon substrates by molecular beam epitaxy is demonstrated. Multimodal electron microscopy and spectroscopy techniques reveal a direct correlation between structural, compositional, and optical properties of TGO and the functional properties of the photodetectors. Wavelength dispersive x-ray spectroscopy results accurately determine Sn concentrations (x) in the region of 0.020, and room temperature cathodoluminescence (CL) hyperspectral imaging shows changes in the CL emission intensity in TGO compared with a Ga2 O3 sample with no Sn. Alloying Ga2 O3 with Sn is shown to quench the red emission and enhance the blue emission. The increase in blue emission corresponds to the rise in VGa -related deep acceptors responsible for the high gain observed in the TGO detectors. A Ga2 O3 nucleation layer is shown to improve the TGO surface quality and give better device properties compared to TGO grown directly onto the Si substrate, including a higher specific detectivity on the order of 1012 Jones. [ABSTRACT FROM AUTHOR]- Published
- 2021
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31. Experimental and Computational Studies on Cobalt(I)‐Catalyzed Regioselective Allylic Alkylation Reactions.
- Author
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Andreetta, Philip, Martin, Robert T., Souilah, Charafa, Rentería‐Gómez, Ángel, Song, Zhihui, Khorramshahi Bayat, Yas, Ivlev, Sergei, Gutierrez, Osvaldo, and Casitas, Alicia
- Subjects
ALLYLIC alkylation ,COBALT ,FRIEDEL-Crafts reaction ,VISIBLE spectra ,ALKYLATION ,PHOTOCATALYSIS - Abstract
Here, we report the development of cobalt(I)‐catalyzed regioselective allylic alkylation reactions of tertiary allyl carbonates with 1,3‐dicarbonyl compounds. A family of well‐defined tetrahedral cobalt(I) complexes bearing commercially available bidentate bis(phosphine) ligands [(P,P)Co(PPh3)Cl] are synthesized and explored as catalysts in allylic alkylation reactions. The catalyst [(dppp)Co(PPh3)Cl] (dppp=1,3‐Bis(diphenylphosphino)propane) enables the alkylation of a large variety of tertiary allyl carbonates with high yields and excellent regioselectivity for the branched product. Remarkably, this methodology is selective for the activation of tertiary allyl carbonates even in the presence of secondary allyl carbonates. This contrasts with the selectivity observed in cobalt‐catalyzed allylic alkylations enabled by visible light photocatalysis. Mechanistic insights by means of experimental and computational investigations support a Co(I)/Co(III) catalytic cycle. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
32. Experimental and Computational Studies on Cobalt(I)‐Catalyzed Regioselective Allylic Alkylation Reactions.
- Author
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Andreetta, Philip, Martin, Robert T., Souilah, Charafa, Rentería‐Gómez, Ángel, Song, Zhihui, Khorramshahi Bayat, Yas, Ivlev, Sergei, Gutierrez, Osvaldo, and Casitas, Alicia
- Subjects
ALLYLIC alkylation ,COBALT ,FRIEDEL-Crafts reaction ,VISIBLE spectra ,ALKYLATION ,PHOTOCATALYSIS - Abstract
Here, we report the development of cobalt(I)‐catalyzed regioselective allylic alkylation reactions of tertiary allyl carbonates with 1,3‐dicarbonyl compounds. A family of well‐defined tetrahedral cobalt(I) complexes bearing commercially available bidentate bis(phosphine) ligands [(P,P)Co(PPh3)Cl] are synthesized and explored as catalysts in allylic alkylation reactions. The catalyst [(dppp)Co(PPh3)Cl] (dppp=1,3‐Bis(diphenylphosphino)propane) enables the alkylation of a large variety of tertiary allyl carbonates with high yields and excellent regioselectivity for the branched product. Remarkably, this methodology is selective for the activation of tertiary allyl carbonates even in the presence of secondary allyl carbonates. This contrasts with the selectivity observed in cobalt‐catalyzed allylic alkylations enabled by visible light photocatalysis. Mechanistic insights by means of experimental and computational investigations support a Co(I)/Co(III) catalytic cycle. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
33. Live-cell imaging unveils distinct R-loop populations with heterogeneous dynamics.
- Author
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Martin, Robert M, de Almeida, Madalena R, Gameiro, Eduardo, and de Almeida, Sérgio F
- Published
- 2023
- Full Text
- View/download PDF
34. BELB: a biomedical entity linking benchmark.
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Garda, Samuele, Weber-Genzel, Leon, Martin, Robert, and Leser, Ulf
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SCIENTIFIC literature ,SCIENCE in literature ,LANGUAGE models ,TEXT mining ,DATA mining - Abstract
Motivation Biomedical entity linking (BEL) is the task of grounding entity mentions to a knowledge base (KB). It plays a vital role in information extraction pipelines for the life sciences literature. We review recent work in the field and find that, as the task is absent from existing benchmarks for biomedical text mining, different studies adopt different experimental setups making comparisons based on published numbers problematic. Furthermore, neural systems are tested primarily on instances linked to the broad coverage KB UMLS, leaving their performance to more specialized ones, e.g. genes or variants, understudied. Results We therefore developed BELB, a biomedical entity linking benchmark, providing access in a unified format to 11 corpora linked to 7 KBs and spanning six entity types: gene, disease, chemical, species, cell line, and variant. BELB greatly reduces preprocessing overhead in testing BEL systems on multiple corpora offering a standardized testbed for reproducible experiments. Using BELB, we perform an extensive evaluation of six rule-based entity-specific systems and three recent neural approaches leveraging pre-trained language models. Our results reveal a mixed picture showing that neural approaches fail to perform consistently across entity types, highlighting the need of further studies towards entity-agnostic models. Availability and implementation The source code of BELB is available at: https://github.com/sg-wbi/belb. The code to reproduce our experiments can be found at: https://github.com/sg-wbi/belb-exp. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
35. An Unstructured Mesh Approach to Nonlinear Noise Reduction for Coupled Systems.
- Author
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Kirtland, Aaron, Botvinick-Greenhouse, Jonah, DeBrito, Marianne, Osborne, Megan, Johnson, Casey, Martin, Robert S., Araki, Samuel J., and Eckhardt, Daniel Q.
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HALL effect thruster ,PHASE space ,DATA acquisition systems ,ELECTRONIC noise ,VORONOI polygons ,COMPUTATIONAL physics ,NOISE control - Abstract
To address noise inherent in electronic data acquisition systems and real-world sources, Araki et al. [Phys. D, 417 (2021), 132819] demonstrated a grid-based nonlinear technique to remove noise from a chaotic signal, leveraging a clean high-fidelity signal from the same dynamical system and ensemble averaging in multidimensional phase space. This method achieved denoising of a time series data with 100\% added noise but suffered in regions of low data density. To improve this grid-based method, here an unstructured mesh based on triangulations and Voronoi diagrams is used to accomplish the same task. The unstructured mesh more uniformly distributes data samples over mesh cells to improve the accuracy of the reconstructed signal. By empirically balancing bias and variance errors in selecting the number of unstructured cells as a function of the number of available samples, the method achieves asymptotic statistical convergence with known test data and reduces synthetic noise on experimental signals from Hall effect thrusters with greater success than the original grid-based strategy. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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36. A new ape from Türkiye and the radiation of late Miocene hominines.
- Author
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Sevim-Erol, Ayla, Begun, David R., Yavuz, Alper, Tarhan, Erhan, Sözer, Çilem Sönmez, Mayda, Serdar, van den Hoek Ostende, Lars W., Martin, Robert M. G., and Alçiçek, M. Cihat
- Subjects
HOMINIDS ,FOSSIL hominids ,APES ,MIOCENE Epoch ,ORANGUTANS ,RADIATION ,PLEISTOCENE Epoch - Abstract
Fossil apes from the eastern Mediterranean are central to the debate on African ape and human (hominine) origins. Current research places them either as hominines, as hominins (humans and our fossil relatives) or as stem hominids, no more closely related to hominines than to pongines (orangutans and their fossil relatives). Here we show, based on our analysis of a newly identified genus, Anadoluvius, from the 8.7 Ma site of Çorakyerler in central Anatolia, that Mediterranean fossil apes are diverse, and are part of the first known radiation of early members of the hominines. The members of this radiation are currently only identified in Europe and Anatolia; generally accepted hominins are only found in Africa from the late Miocene until the Pleistocene. Hominines may have originated in Eurasia during the late Miocene, or they may have dispersed into Eurasia from an unknown African ancestor. The diversity of hominines in Eurasia suggests an in situ origin but does not exclude a dispersal hypothesis. An 8.7 million year old ape from Türkiye shows that Mediterranean fossil apes are diverse and part of the first known radiation of hominines (African apes and humans). Our phylogenetic analysis suggests that hominines originate in Europe. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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- View/download PDF
37. Infection reporting in patients undergoing irreversible electroporation of locally advanced pancreatic cancer.
- Author
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Filson, Anthony and Martin, Robert C. G.
- Published
- 2023
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38. Electroluminescence hyperspectral imaging of light-emitting diodes using a liquid crystal tunable filter.
- Author
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Edwards, Paul R., Bruckbauer, Jochen, Cameron, Douglas, and Martin, Robert W.
- Subjects
CRYSTAL filters ,LIQUID crystals ,OPTOELECTRONIC devices ,MAGNIFYING glasses ,LIGHT emitting diodes ,ELECTROLUMINESCENCE ,CAMCORDERS - Abstract
We demonstrate the use of a low-cost liquid-crystal-based wavelength-tunable filter and CMOS video camera to add hyperspectral imaging capabilities to a probe station equipped with a simple optical microscope. The resultant setup is used to rapidly resolve the spectral and spatial variations in electroluminescence typically observed for In
x Ga1−x N/GaN light-emitting diodes. Applying standard statistical analyses of variation within the multivariate datasets, such as moments and principal components, we observe inhomogeneities on a spectral scale significantly smaller than the bandwidth of the tunable filter. The resultant tool offers an alternative to scanning beam luminescence techniques for high-throughput hyperspectral analysis of optoelectronic devices. [ABSTRACT FROM AUTHOR]- Published
- 2023
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- View/download PDF
39. Neural networks for inline segmentation of image data in punching processes.
- Author
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Lorenz, Maximilian, Martin, Robert J., Bruecklmayr, Thomas, Donhauser, Christian, and Pinzer, Bernd R.
- Subjects
IMAGE segmentation ,IMAGE processing ,ELECTRONIC data processing ,BURNISHING - Abstract
Punching is a process that is sensitive to a multitude of parameters. The estimation of part and punch quality is often based on expert knowledge and trial-and-error methods, mostly carried out as a separate offline process analysis. In a previous study, we developed an optical inline monitoring system with subsequent image processing which showed promising results in terms of capturing every manufactured part, but was limited by slow image processing. Here, we present a more efficient image processing technique based on neural networks. For our approach, we manually identify the burnish parts in images based on criteria established via an expert survey in order to generate a training dataset. We then employ a combination of region-based and boundary-based losses to optimize the neural network towards a segmentation of the burnish surface which allows for an accurate measurement of the burnish height. The hyperparameter optimization is based on custom evaluation metrics that reflect the requirements of the burnish surface identification problem as well. After comparing different neural network architectures, we focus on optimizing the backbone of the UNet++ structure for our task. The promising results demonstrate that neural networks are indeed capable of an inline segmentation that can be used for measuring the burnish surface of punching parts. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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40. A Case Report of Behcet's Syndrome in an African American Man.
- Author
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Norton, Andrew, Martin, Robert, Pranga, Katrianna, Welch, Ron, Thapa, Angelica, and Wade, Matt
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AFRICAN American men ,DELAYED diagnosis ,SILK Road ,TRADE routes ,BEHCET'S disease ,AFRICAN Americans - Abstract
Behçet's disease is a rare systemic vasculitis of characterized by oral and genital apthous ulceration as well as GI, neurological, vascular and dermatological manifestation. It is most common along the Silk Route, a series of trade routes spanning across Asia into the Mediterranean Sea. This case describes the presentation of Behçet's in an African American male whose diagnosis and treatment were delayed due to the team's concern for an infectious process or cerebrovascular event as well as the later discovery of additional symptoms consistent with Behçet's classical manifestations in the patient. [ABSTRACT FROM AUTHOR]
- Published
- 2023
41. Luminescence behavior of semipolar (101¯1) InGaN/GaN "bow-tie" structures on patterned Si substrates.
- Author
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Bruckbauer, Jochen, Trager-Cowan, Carol, Hourahine, Ben, Winkelmann, Aimo, Vennéguès, Philippe, Ipsen, Anja, Yu, Xiang, Zhao, Xunming, Wallace, Michael J., Edwards, Paul R., Naresh-Kumar, G., Hocker, Matthias, Bauer, Sebastian, Müller, Raphael, Bai, Jie, Thonke, Klaus, Wang, Tao, and Martin, Robert W.
- Subjects
CATHODOLUMINESCENCE ,LUMINESCENCE ,QUANTUM wells ,INTERFACE structures ,LOW temperatures - Abstract
In this work, we report on the innovative growth of semipolar "bow-tie"-shaped GaN structures containing InGaN/GaN multiple quantum wells (MQWs) and their structural and luminescence characterization. We investigate the impact of growth on patterned (113) Si substrates, which results in the bow-tie cross section with upper surfaces having the (10 1 ¯ 1) orientation. Room temperature cathodoluminescence (CL) hyperspectral imaging reveals two types of extended defects: black spots appearing in intensity images of the GaN near band edge emission and dark lines running parallel in the direction of the Si stripes in MQW intensity images. Electron channeling contrast imaging (ECCI) identifies the black spots as threading dislocations propagating to the inclined (10 1 ¯ 1) surfaces. Line defects in ECCI, propagating in the [ 1 2 ¯ 10 ] direction parallel to the Si stripes, are attributed to misfit dislocations (MDs) introduced by glide in the basal (0001) planes at the interfaces of the MQW structure. Identification of these line defects as MDs within the MQWs is only possible because they are revealed as dark lines in the MQW CL intensity images, but not in the GaN intensity images. Low temperature CL spectra exhibit additional emission lines at energies below the GaN bound exciton emission line. These emission lines only appear at the edge or the center of the structures where two (0001) growth fronts meet and coalesce (join of the bow-tie). They are most likely related to basal-plane or prismatic stacking faults or partial dislocations at the GaN/Si interface and the coalescence region. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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- View/download PDF
42. A cross-linkable, organic down-converting material for white light emission from hybrid LEDs.
- Author
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Yang, Hao, Bruckbauer, Jochen, Kanibolotska, Lyudmyla, Kanibolotsky, Alexander L., Cameron, Joseph, Wallis, David J., Martin, Robert W., and Skabara, Peter J.
- Abstract
The use of organic materials and the replacement of rare-earth elements in the making of light-emitting devices has been increasingly popular over the last decades. Herein, the synthesis and characterisation of a novel organic green-emitting material (GreenCin), based on a fluorene-benzothiadiazole-fluorene (Flu-BT-Flu) core structure, and its performance as a down-converting layer in tandem with commercial blue light-emitting diodes (LEDs) for white light emission are reported. This material has been functionalised with cinnamate-groups to enable the emissive material to react with the cross-linker tetra(cinnamoyloxymethyl)methane (TCM), to produce stable films with high performance in hybrid LEDs. The hybrid devices can generate white light with a good colour rendering index (CRI) of 69. The hybrid devices also have ×2.6 increased luminous efficacy (107 lm W
−1 ) and ×2.4 increased radiant flux (24 mW) when compared with hybrid devices using non-cross-linked analogues of GreenCin. Additionally, the hybrid devices containing GreenCin have a high blue-to-white efficacy value (defined by dividing the luminous flux of a hybrid device by the radiant flux of the underlying blue LED), of 213 lm W−1 , for which inorganic phosphors have values in the range of 200–300 lm W−1 . [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
43. Optimal Dosing and Patient Selection for Electrochemotherapy in Solid Abdominal Organ and Bone Tumors.
- Author
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Martin, Cora H. and Martin, Robert C. G.
- Subjects
PATIENT selection ,BONE metastasis ,DISEASE relapse ,KIDNEYS ,PANCREAS ,LIFE expectancy - Abstract
The primary aim of this study was to analyze studies that use electrochemotherapy (ECT) in "deep-seated" tumors in solid organs (liver, kidney, bone metastasis, pancreas, and abdomen) and understand the similarities between patient selection, oncologic selection, and use of new procedures and technology across the organ systems to assess response rates. A literature search was conducted using the term "Electrochemotherapy" in the title field using publications from 2017 to 2023. After factoring in inclusion and exclusion criteria, 29 studies were analyzed and graded based on quality in full. The authors determined key patient and oncologic selection characteristics and ECT technology employed across organ systems that yielded overall responses, complete responses, and partial responses of the treated tumor. It was determined that key selection factors included: the ability to be administered bleomycin, life expectancy greater than three months, unrespectability of the lesion being treated, and a later stage, more advanced cancer. Regarding oncologic selection, all patient cohorts had received chemotherapy or surgery previously but had disease recurrence, making ECT the only option for further treatment. Lastly, in terms of the use of technology, the authors found that studies with better response rates used the ClinporatorTM and updated procedural guidelines by SOP. Thus, by considering patient, oncologic, and technology selection, ECT can be further improved in treating lesions in solid organs. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
44. CFD Analysis of Biofouling Effect on Submarine Resistance and Wake.
- Author
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Utama, I Ketut Aria Pria, Farhan, Fertisio, Nasirudin, Ahmad, Ariesta, Rizky Chandra, and Renilson, Martin Robert
- Subjects
FINITE volume method ,FOULING ,SUBMARINES (Ships) ,COMPUTATIONAL fluid dynamics ,SHIP hull fouling - Abstract
It is well known that biofouling increases a ship's resistance and nominal wake. For submarines, any change to the circumferential variation of the nominal wake in the propeller plane will affect the variation of the flow over the propeller blade, and hence the fluctuating forces, and noise, generated by the propeller. The ANSYS FLUENT commercial Reynolds-Averaged Navier Stokes Computational Fluid Dynamics solver was used to investigate the influence of both the longitudinal and vertical distribution of biofouling on the resistance and wake, including the circumferential variation of the nominal wake, on a submarine, using the well-known Suboff standard submarine. For the present work, the k-ε turbulence model was selected, as this is commonly used in this field and is generally considered acceptable. To handle different boundary layer thicknesses in the flow fields, the whole y+ formulation was employed, enabling automatic switching between low and high Reynolds boundary wall models. The numerical solver used for the simulations is based on the finite volume method, which discretizes the RANS equations. In this approach, a segregated model was utilized in the solver, and the convection terms were discretized using the second-order upwind scheme to enhance solution accuracy. The criteria for the near wall are between 30 and 100, and the value of y+ for the present case is 84. It is shown that fouling over only the forward third of the submarine results in a greater increase in resistance than fouling over only the aft third. Fouling over only the lower half of the submarine results in greater resistance than fouling over only the forward third, but less than fouling over the whole of the hull. Fouling over only the forward third of the hull has less influence on the circumferential variation of the wake than fouling over the aft third only of the hull. The results show the importance of keeping the forward area of the hull clean when considering resistance only, whereas keeping the aft area of the hull clean is important when considering the uniformity of the nominal wake into the propeller. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
45. Chlorine retention enables the indoor light harvesting of triple halide wide bandgap perovskites.
- Author
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Wang, Shaoyang, Edwards, Paul R., Abdelsamie, Maged, Brown, Peter, Webster, David, Ruseckas, Arvydas, Rajan, Gopika, Neves, Ana I. S., Martin, Robert W., Sutter-Fella, Carolin M., Turnbull, Graham A., Samuel, Ifor D. W., and Jagadamma, Lethy Krishnan
- Abstract
Indoor photovoltaics are receiving tremendous attention due to the continuous development of the Internet of Things. The present study reports how the fast processing of the triple halide perovskite enables the retention of chlorine and the beneficial role of chlorine in enhancing the indoor light harvesting of a wide bandgap triple anion (TA) perovskite CH
3 NH3 PbI2.6 Br0.2 Cl0.2 . The kinetics of chlorine incorporation/escape investigated by in situ grazing incidence wide-angle X-ray scattering revealed the escape of chlorine after the first ten minutes of thermal annealing and the findings were corroborated with elemental analysis by wavelength dispersive X-ray spectroscopy. The best-performing TA perovskite indoor-photovoltaic device achieved a steady-state power conversion efficiency (PCE) of 25.1% with an output power density of ∼75 μW cm−2 under 1000 lux indoor illumination (0.3 mW cm−2 irradiance). Improved crystalline quality, reduced density of trap states and longer carrier lifetime were achieved by the triple anion alloying method. The detrimental role of the commonly used hole transporting layer (HTL) of Spiro-MeOTAD under indoor lighting conditions leading to J–V hysteresis was also investigated, which could then be effectively suppressed by replacing Spiro-MeOTAD with undoped P3HT. The optimized TA perovskite indoor PV cells were then successfully used to wirelessly power a textile fiber-based temperature sensor. The results from the present study demonstrate a novel route to incorporate chlorine effectively and maximize the steady state power output from halide perovskite indoor photovoltaic devices and their promising potential for the IoT industry. [ABSTRACT FROM AUTHOR]- Published
- 2023
- Full Text
- View/download PDF
46. Trustworthiness as information: Satisfying the understanding condition of valid consent.
- Author
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Martin, Robert K.
- Subjects
ETHICS ,INFORMED consent (Medical law) ,INFORMATION literacy ,MEDICAL ethics ,COMMUNICATION ,ACCESS to information ,TRUST - Abstract
Within medical ethics, there is widespread agreement that morally valid consent includes an understanding condition. Disagreement centers on what is meant by that understanding condition. Tom Dougherty proposed that this understanding condition should be divided into the two mutually exclusive categories of descriptive information and contextual information. Further, Dougherty argues that each type of information is necessary to satisfy the understanding condition. In contrast, I argue that when the deontic aspect of valid consent is in view, each type of information can be sufficient to satisfy the understanding condition on its own. Moreover, by analyzing delegation, which is conceptually related to consent since both are morally transformative actions, I show that delegation often depends not on descriptive or contextual information but on trust. So, I argue that trustworthiness can also be a type of information that does the same work as descriptive and contextual information in satisfying the understanding condition for valid consent. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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- View/download PDF
47. Learning dynamics on invariant measures using PDE-constrained optimization.
- Author
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Botvinick-Greenhouse, Jonah, Martin, Robert, and Yang, Yunan
- Subjects
INVARIANT measures ,INVERSE problems ,DYNAMICAL systems - Abstract
We extend the methodology in Yang et al. [SIAM J. Appl. Dyn. Syst. 22, 269–310 (2023)] to learn autonomous continuous-time dynamical systems from invariant measures. The highlight of our approach is to reformulate the inverse problem of learning ODEs or SDEs from data as a PDE-constrained optimization problem. This shift in perspective allows us to learn from slowly sampled inference trajectories and perform uncertainty quantification for the forecasted dynamics. Our approach also yields a forward model with better stability than direct trajectory simulation in certain situations. We present numerical results for the Van der Pol oscillator and the Lorenz-63 system, together with real-world applications to Hall-effect thruster dynamics and temperature prediction, to demonstrate the effectiveness of the proposed approach. [ABSTRACT FROM AUTHOR]
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- 2023
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48. A meta-analysis and systematic review of the comparison of laparoscopic ablation to percutaneous ablation for hepatic malignancies.
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Musick, Joslin R., Gaskins, Jeremy T., and Martin, Robert C. G.
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ABLATION techniques ,PATIENT selection ,ODDS ratio ,DISEASE relapse ,CONFIDENCE intervals - Abstract
Background: The optimal access for thermal ablation of the liver has not been evaluated in the literature for the laparoscopic versus percutaneous techniques. The aim of this manuscript was to determine the optimal ablation technique and patient selection for hepatic malignancies by comparing the efficacy and recurrence-free survival of laparoscopic and percutaneous thermal ablation. Methods: A detailed literature search was made in PubMed, Web of Science, Google scholar, and EMBASE for related research publications. The data were extracted and assessed by two reviewers independently. Analysis of pooled data was performed, and Odds Ratio (OR) or Hazard Ratio (HR) with corresponding confidence intervals (CIs) was calculated and summarized respectively. Results: A total of 10 articles were included with 1916 ablation patients. Laparoscopic ablation success (Median 100%) was found to be higher than percutaneous ablation success (median 89.4%) (p = ns). There was a higher percentage of both local and non-local hepatic recurrence in the patients treated with percutaneous ablation versus laparoscopic ablation. Meta-analysis indicated no difference in the adjusted hazard rate of recurrence by procedure type (p = 0.94). Laparoscopic ablation had a higher percentage of complications compared to percutaneous ablation (median lap 14.5% vs. perc 3.3%). Conclusions: While laparoscopic and percutaneous ablation are both effective interventions for hepatic malignancies, laparoscopic ablation was found to have improved ablation success and less local and non-local hepatic recurrence compared to percutaneous ablation. [ABSTRACT FROM AUTHOR]
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- 2023
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49. Transition metal-free photochemical C–F activation for the preparation of difluorinated-oxindole derivatives.
- Author
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Matsuo, Bianca, Majhi, Jadab, Granados, Albert, Sharique, Mohammed, Martin, Robert T., Gutierrez, Osvaldo, and Molander, Gary A.
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- 2023
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50. Ensquared Energy and Optical Centroid Efficiency in Optical Sensors: Part 1, Theory.
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Strojnik, Marija, Bravo-Medina, Beethoven, Martin, Robert, and Wang, Yaujen
- Subjects
OPTICAL sensors ,OPTICAL remote sensing ,FOCAL plane arrays sensors ,CENTROID ,IMAGING systems ,OPTICAL images - Abstract
High-performance megapixel focal plane arrays with small pixels have been widely used in modern optical remote sensing, astronomical, and surveillance instruments. In the prediction models applied in the traditional instrument performance analysis, the image of a point source is assumed to fall on the center of a detector pixel. A geometrical image of a point source in the realistic optical system may actually fall on any position on the detector pixel because the sensor's line of sight includes pointing errors and jitter. This traditional assumption may lead to an optimistic error, estimated at between 10% and 20%. We present the critical factors that impact the performance estimate in a realistic instrument design based on the prediction for the noise-equivalent power (NEP). They are the optical centroid efficiency (OCE) and the ensquared energy, or more precisely, the energy on the rectangular detector pixel (EOD). We performed the simulation studies for imaging with an optical system with and without a generalized rectangular central obscuration. [ABSTRACT FROM AUTHOR]
- Published
- 2023
- Full Text
- View/download PDF
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