2,253 results on '"Florian K"'
Search Results
2. Beyond the Slopes and Highways: Endovascular Repair of Blunt Traumatic Aortic Injuries after Skiing versus Motor Vehicle Accidents
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David Wippel, Maximilian Lutz, Michaela Kluckner, Leonhard Gruber, Alexander Loizides, Jennifer Fischer, Elke R. Gizewski, Florian K. Enzmann, and Sabine Wipper
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BTAI ,blunt aortic injury ,TEVAR ,aortic trauma ,skiing accident ,motor vehicle accident ,Medicine - Abstract
Background: Blunt traumatic aortic injury (BTAI) is a potentially fatal condition, typically resulting from high-velocity trauma. To date, little is known about this type of injury among skiers, who form the largest patient cohort with aortic injuries in the alpine region of Tyrol, Austria. Methods: This retrospective, single-center study at the University Hospital of Innsbruck analyzed patients who underwent endovascular treatment for blunt traumatic aortic injury from 2005 to 2023. Patient data were extracted from electronic and digitalized medical history records. Subsequent analyses compared the baseline characteristics and clinical results of the skiing accident (SA) group to the motor vehicle accident (MVA) group. Results: A total of 48 BTAI patients receiving TEVAR were included, 25 (52%) from SAs versus 23 (48%) from MVAs, who were predominantly male (92% vs. 78.3%). Despite similar preoperative risk profiles and ASA Scores (1.44 vs. 1.74) and no marked differences in BTAI injury grades or the affected aortic zones, significant disparities emerged: the SA group experienced shorter median ICU stays (3 vs. 11 days, p = 0.0007), fewer concomitant injuries (5 vs. 7, p = 0.005), and lower Injury Severity Scores (ISSs) (29 vs. 33, p = 0.003) than their MVA counterparts. The presence of rib fractures alongside other thoracic injuries, such as lung injury, pneumothorax, or hemothorax, was strongly correlated with BTAI in patients following skiing accidents (OR = 128.5). Conclusions: The injury severities and locations of BTAI in SA patients were comparable to those in MVA patients, indicating similar mechanisms of thoracic trauma. However, the SA patients experienced fewer concurrent pelvic and extremity fractures, had less post-procedural morbidity, and required shorter ICU stays. The presence of rib fractures combined with other thoracic injuries strongly suggests BTAI. These indicators should lead to prompt imaging and appropriate therapy.
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- 2024
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3. Testing the Posterior Chain: Diagnostic Accuracy of the Bunkie Test versus the Isokinetic Hamstrings/Quadriceps Measurement in Patients with Self-Reported Knee Pain and Healthy Controls
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Anna Gabriel, Andreas Konrad, Nadine Herold, Thomas Horstmann, Robert Schleip, and Florian K. Paternoster
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myofascial diagnostics ,myofascial assessments ,H/Q ratio ,dorsal chain ,superficial backline ,myofascial chain ,Medicine - Abstract
(1) Background: The isokinetic measurement (IM) of the leg muscles is well established but costly, whereas the Bunkie Test (BT) is a rarely investigated but easy-to-conduct functional test to evaluate the total posterior chain. Although the tests differ in aim and test structures, both have their justification in the assessment process. Therefore, this study evaluated the diagnostic accuracy of the BT and the IM. (2) Methods: 21 participants (9 female, 12 male; age, 26.2 ± 5.26 years; weight 73.8 ± 14.6 kg; height 176.0 ± 9.91 cm) and 21 patients (9 female, 12 male; age, 26.5 ± 5.56 years; weight, 72.6 ± 16.9 kg; height 177.0 ± 10.1 cm) with self-reported pain in the knee performed the IM and the BT. For IM, we calculated the ratio of the knee mean flexor/extensor peak torque (H/Q ratio) for 60°/s and 120°/s, and BT performance was measured in seconds. We classified the IM (p-value of ≤0.05 is considered significant. (3) Results: The sensitivity for the BT was 0.89, 95% CI [0.67, 0.99], and the specificity was 0.52 [0.30, 0.74]. For the IM, the sensitivity was 0.14 [0.03, 0.36] for 60°/s and 0.05 [0.00, 0.24] for 120°/s, and the specificity was 0.70 [0.46, 0.88] for 60°/s and 0.90 [0.68, 0.99] for 120°/s. The results of the Chi-Square tests were significant for the BT (χ2 (1) = 6.17, p = 0.01) but not for the IM (60°/s: χ2 (1) = 0.70, p = 0.40; 120°/s: χ2 (1) = 0.00, p = 0.97). (4) Conclusions: Patients were more likely to obtain a positive test result for the BT but not for the IM.
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- 2024
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4. A preclinical model of cutaneous melanoma based on reconstructed human epidermis
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Anna Leikeim, Maximiliane Wußmann, Freia F. Schmidt, Nuno G. B. Neto, Franziska Benz, Kendra Tiltmann, Corinna Junger, Michael G. Monaghan, Bastian Schilling, and Florian K. Groeber-Becker
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Medicine ,Science - Abstract
Abstract Malignant melanoma is among the tumor entities with the highest increase of incidence worldwide. To elucidate melanoma progression and develop new effective therapies, rodent models are commonly used. While these do not adequately reflect human physiology, two-dimensional cell cultures lack crucial elements of the tumor microenvironment. To address this shortcoming, we have developed a melanoma skin equivalent based on an open-source epidermal model. Melanoma cell lines with different driver mutations were incorporated into these models forming distinguishable tumor aggregates within a stratified epidermis. Although barrier properties of the skin equivalents were not affected by incorporation of melanoma cells, their presence resulted in a higher metabolic activity indicated by an increased glucose consumption. Furthermore, we re-isolated single cells from the models to characterize the proliferation state within the respective model. The applicability of our model for tumor therapeutics was demonstrated by treatment with a commonly used v-raf murine sarcoma viral oncogene homolog B (BRAF) inhibitor vemurafenib. This selective BRAF inhibitor successfully reduced tumor growth in the models harboring BRAF-mutated melanoma cells. Hence, our model is a promising tool to investigate melanoma development and as a preclinical model for drug discovery.
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- 2022
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5. Preoperative anxiety as predictor of perioperative clinical events following carotid surgery: a prospective observational study
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Manuela Aspalter, Florian K. Enzmann, Thomas J. Hölzenbein, Wolfgang Hitzl, Florian Primavesi, Lucia Algayerova, Patrick Nierlich, Christoph Kartnig, Reinald Seitelberger, and Klaus Linni
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Asymptomatic carotid artery stenosis ,Carotid endarterectomy ,Hospital anxiety and depression scale ,Spielberger state and trait anxiety inventory ,Surgery ,RD1-811 - Abstract
Abstract Background Psychological factors like anxiety and depression are recognised to play a causal role in the development of cardiovascular disease and they may also influence outcome after vascular surgery procedures. The aim of this study was to investigate the association of anxiety and depression with postoperative outcome following elective carotid surgery. Methods Single centre prospective observational study of patients treated for asymptomatic carotid artery stenosis at an academic vascular surgery centre. Preoperative anxiety and depression were evaluated using self-reporting questionnaires: Spielberger State-Trait Anxiety Inventory (STAI-S/-T) and Hospital Anxiety and Depression Scale (HADS-A/-D). Postoperative morbidity and mortality were assessed with the primary composite endpoint of stroke, myocardial infarction (MI) and death. Standard reporting guidelines for carotid disease were applied. Results From June 2012 to November 2015, 393 carotid endarterectomies (CEA) were performed at our institution. Out of those, 98 asymptomatic patients were available for analysis (78% male; median age, 71.1 years). Median scores of self-reporting questionnaires did not differ from published data of the general population (STAI-T, trait component, median, 36; IQR, 31-42.75; STAI-S, state component, median, 38; IQR, 32-43; HADS-A median, 6; IQR, 3-8; HADS-D median, 4; IQR, 2-7). Cardiovascular risk factors were similar in anxious and non-anxious patients. The composite endpoint of stroke, MI and death occurred significantly more often in patients presenting with a preoperative HADS-A score higher than 6 (10.5%, 95% CI, 3-25; p =.020). Conclusions The present study indicates that preoperative anxiety is associated with the occurrence of intra- and postoperative neurological events in patients undergoing CEA. Patients who had a preoperative HADS-A score of 6 or less had a very low probability of experiencing these complications.
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- 2021
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6. Long-Term Outcome of Bypass Surgery versus Endovascular Revascularization in Long Femoropopliteal Lesions
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Michaela Kluckner, Leonhard Gruber, David Wippel, Daniela Lobenwein, Werner Westreicher, Manuela Pilz, and Florian K. Enzmann
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prosthetic graft ,vein graft ,nitinol stent ,bypass ,peripheral arterial disease ,patency rates ,Medicine - Abstract
Long-term follow-up data comparing surgical and endovascular revascularization of femoropopliteal lesions is rarely reported. This study presents 4-year results of revascularization for long femoropopliteal lesions (Trans-Atlantic Inter-Society Consensus Types C and D) with vein bypass (VBP), polytetrafluorethylene bypass (PTFE), and endovascular intervention with a nitinol stent (NS). Data from a randomized-controlled trial on VBP and NS was compared with a retrospective patient cohort using PTFE with the same inclusion and exclusion criteria. Primary, primary assisted, and secondary patency, as well as changes in Rutherford categories and limb salvage rates, are reported. Between 2016 and 2020, 332 femoropopliteal lesions underwent revascularization. The lesion lengths and basic patient characteristics were similar between the groups. 49% of the patients presented with chronic limb threatening ischemia at the time of revascularization. During the four-year follow-up, primary patency was comparable for all three groups. Primary assisted and secondary patency were significantly higher after VBP, while PTFE and NS had similar results. Clinical improvement was also significantly superior after VBP. After four years of follow-up, patency rates as well as the clinical outcome clearly favor VBP. If no vein is available, NS is as effective as PTFE bypass with regard to patency and clinical outcome.
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- 2023
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7. Structure of the mature Rous sarcoma virus lattice reveals a role for IP6 in the formation of the capsid hexamer
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Martin Obr, Clifton L. Ricana, Nadia Nikulin, Jon-Philip R. Feathers, Marco Klanschnig, Andreas Thader, Marc C. Johnson, Volker M. Vogt, Florian K. M. Schur, and Robert A. Dick
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Science - Abstract
Inositol hexakisphosphate (IP6) is a known assembly cofactor for HIV-1. Here, the authors show the role of IP6 in the assembly of the Rous sarcoma virus (RSV). Reported cryo-ET structures of mature capsid-like particles (CLPs) suggest that IP6 modulates the formation of capsid polyhedrons of variable shape.
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- 2021
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8. Cul3 regulates cytoskeleton protein homeostasis and cell migration during a critical window of brain development
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Jasmin Morandell, Lena A. Schwarz, Bernadette Basilico, Saren Tasciyan, Georgi Dimchev, Armel Nicolas, Christoph Sommer, Caroline Kreuzinger, Christoph P. Dotter, Lisa S. Knaus, Zoe Dobler, Emanuele Cacci, Florian K. M. Schur, Johann G. Danzl, and Gaia Novarino
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Science - Abstract
De novo loss of function mutations in the ubiquitin ligase-encoding gene Cullin3 (CUL3) lead to autism spectrum disorder (ASD). Here, the authors show that Cul3 is essential to regulate neuronal migration by tightly regulating Plastin3 (Pls3). Pls3 cell-autonomously regulates cell migration by regulating the actin cytoskeleton organization.
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- 2021
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9. Cryo-electron tomography structure of Arp2/3 complex in cells reveals new insights into the branch junction
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Florian Fäßler, Georgi Dimchev, Victor-Valentin Hodirnau, William Wan, and Florian K. M. Schur
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Science - Abstract
The actin-related protein (Arp)2/3 complex nucleates branched actin filament networks pivotal for cell migration, endocytosis and pathogen infection. Here, authors report a 9.0 Å resolution structure of the actin filament Arp2/3 complex branch junction in cells using cryo-electron tomography and subtomogram averaging.
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- 2020
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10. Charting the Exciton–Polariton Landscape of WSe2 Thin Flakes by Cathodoluminescence Spectroscopy
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Masoud Taleb, Fatemeh Davoodi, Florian K. Diekmann, Kai Rossnagel, and Nahid Talebi
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cathodoluminescence spectroscopy ,electron microscopy ,exciton–polariton interaction ,transition-metal dichalcogenides ,Applied optics. Photonics ,TA1501-1820 ,Optics. Light ,QC350-467 - Abstract
Semiconducting transition‐metal dichalcogenides (TMDCs) provide a fascinating discovery platform for strong light–matter interaction effects in the visible spectrum at ambient conditions. While most of the works have focused on hybridizing excitons with resonant photonic modes of external mirrors, cavities, or nanostructures, intriguingly, TMDC flakes of subwavelength thickness can themselves act as nanocavities. Herein, the optical response of such freestanding planar waveguides of WSe2 by means of cathodoluminescence spectroscopy is determined. Strong exciton–photon interaction effects that foster long‐range propagating exciton–polaritons and enable direct imaging of the energy transfer dynamics originating from cavity‐like Fabry–Pérot resonances are revealed. Furthermore, confinement effects due to discontinuities in the flakes are demonstrated as an efficient means to tailor mode energies, spin–momentum couplings, and the exciton–photon coupling strength, as well as to promote photon‐mediated exciton–exciton interactions. The combined experimental and theoretical results provide a deeper understanding of exciton–photon self‐hybridization in semiconducting TMDCs and may pave the way to optoelectronic nanocircuits exploiting exciton–photon interaction beyond the routinely employed two‐oscillator coupling effects.
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- 2022
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11. Impacts of Telomeric Length, Chronic Hypoxia, Senescence, and Senescence-Associated Secretory Phenotype on the Development of Thoracic Aortic Aneurysm
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Thomas Aschacher, Daniela Geisler, Verena Lenz, Olivia Aschacher, Bernhard Winkler, Anne-Kristin Schaefer, Andreas Mitterbauer, Brigitte Wolf, Florian K. Enzmann, Barbara Messner, Günther Laufer, Marek P. Ehrlich, Martin Grabenwöger, and Michael Bergmann
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telomere ,aneurysm ,DNA damage ,senescence-associated secretory phenotype ,cell death ,thoracic aorta ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
Thoracic aortic aneurysm (TAA) is an age-related and life-threatening vascular disease. Telomere shortening is a predictor of age-related diseases, and its progression is associated with premature vascular disease. The aim of the present work was to investigate the impacts of chronic hypoxia and telomeric DNA damage on cellular homeostasis and vascular degeneration of TAA. We analyzed healthy and aortic aneurysm specimens (215 samples) for telomere length (TL), chronic DNA damage, and resulting changes in cellular homeostasis, focusing on senescence and apoptosis. Compared with healthy thoracic aorta (HTA), patients with tricuspid aortic valve (TAV) showed telomere shortening with increasing TAA size, in contrast to genetically predisposed bicuspid aortic valve (BAV). In addition, TL was associated with chronic hypoxia and telomeric DNA damage and with the induction of senescence-associated secretory phenotype (SASP). TAA-TAV specimens showed a significant difference in SASP-marker expression of IL-6, NF-κB, mTOR, and cell-cycle regulators (γH2AX, Rb, p53, p21), compared to HTA and TAA-BAV. Furthermore, we observed an increase in CD163+ macrophages and a correlation between hypoxic DNA damage and the number of aortic telocytes. We conclude that chronic hypoxia is associated with telomeric DNA damage and the induction of SASP in a diseased aortic wall, promising a new therapeutic target.
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- 2022
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12. Pharmaceutical Development of Nanostructured Vesicular Hydrogel Formulations of Rifampicin for Wound Healing
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Chantal M. Wallenwein, Verena Weigel, Götz Hofhaus, Namrata Dhakal, Wolfgang Schatton, Svetlana Gelperina, Florian K. Groeber-Becker, Jennifer Dressman, and Matthias G. Wacker
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hydrogel ,marine sponge collagen ,hyaluronic acid ,rifampicin ,liposomes ,wound healing ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
Chronic wounds exhibit elevated levels of inflammatory cytokines, resulting in the release of proteolytic enzymes which delay wound-healing processes. In recent years, rifampicin has gained significant attention in the treatment of chronic wounds due to an interesting combination of antibacterial and anti-inflammatory effects. Unfortunately, rifampicin is sensitive to hydrolysis and oxidation. As a result, no topical drug product for wound-healing applications has been approved. To address this medical need two nanostructured hydrogel formulations of rifampicin were developed. The liposomal vesicles were embedded into hydroxypropyl methylcellulose (HPMC) gel or a combination of hyaluronic acid and marine collagen. To protect rifampicin from degradation in aqueous environments, a freeze-drying method was developed. Before freeze-drying, two well-defined hydrogel preparations were obtained. After freeze-drying, the visual appearance, chemical stability, residual moisture content, and redispersion time of both preparations were within acceptable limits. However, the morphological characterization revealed an increase in the vesicle size for collagen–hyaluronic acid hydrogel. This was confirmed by subsequent release studies. Interactions of marine collagen with phosphatidylcholine were held responsible for this effect. The HPMC hydrogel formulation remained stable over 6 months of storage. Moving forward, this product fulfills all criteria to be evaluated in preclinical and clinical studies.
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- 2022
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13. Residual force enhancement in humans: Is there a true non‐responder?
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Florian K. Paternoster, Denis Holzer, Anna Arlt, Ansgar Schwirtz, and Wolfgang Seiberl
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eccentric muscle action ,electrical stimulation ,force enhancement ,history‐dependence ,lengthening contraction ,voluntary muscle action ,Physiology ,QP1-981 - Abstract
Abstract When an active muscle is stretched and kept isometrically active, the resulting force is enhanced compared to a purely isometric reference contraction at the same muscle length and activity; a generally accepted muscle property called residual force enhancement (rFE). Interestingly, studies on voluntary muscle action regularly identify a significant number of participants not showing rFE. Therefore, the aim was to unmask possible confounders for this non‐responsive behavior. Ten participants performed maximum voluntary isometric plantarflexion contractions with and without preceding stretch. Contractions were accompanied by the assessment of voluntary activation using the twitch‐interpolation technique. The same test protocol was repeated four additional times with a least on day rest in‐between. Additionally, at the first and fifth sessions, a submaximal tetanic muscle‐stimulation condition was added. At both muscle‐stimulation sessions mean rFE higher 10% (p
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- 2021
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14. Long-Term Results of Endovascular Treatment with Nitinol Stents for Femoropopliteal TASC II C and D Lesions
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Michaela Kluckner, Patrick Nierlich, Wolfgang Hitzl, Thomas Aschacher, Alexandra Gratl, Sabine Wipper, Manuela Aspalter, Herve Moussalli, Klaus Linni, and Florian K. Enzmann
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femoropopliteal lesion ,nitinol stent ,peripheral arterial disease ,TASC ,Medicine (General) ,R5-920 - Abstract
Background and Objectives: The feasibility of endovascular treatment (EVT) for Trans-Atlantic Inter-Society Consensus (TASC) II C and D femoropopliteal artery lesions has been described, but no prospective study has performed a long-term follow-up. The aim of this study was to report the long-term results of nitinol stents (NS) for the treatment of long femoropopliteal lesions. Materials and Methods: A single-center prospective, randomized controlled trial (RCT) comparing EVT with NS and vein bypass surgery was previously performed. The EVT group’s follow-up was extended and separately analyzed with primary patency as the primary endpoint. The secondary endpoints were technical success, secondary patency, reinterventions, limb salvage, survival, complications, and clinical improvement. Results: Between 2016 and 2020, 109 limbs in 103 patients were included. A total of 48 TASC II C and 61 TASC II D lesions with a mean lesion length of 264 mm were reported. In 53% of limbs, the indication for treatment was chronic limb-threatening ischemia. The median follow-up was 45 months. Technical success was achieved in 88% of cases, despite 23% of the lesions being longer than 30 cm (retrograde popliteal access in 22%). At four-year follow-up, primary patency, secondary patency, and freedom from target lesion revascularizations were 35%, 48%, and 58%, respectively. Limb salvage and survival were 90% and 80% at 4 years. Clinical improvement of at least one Rutherford category at the end of follow-up was achieved in 83% of limbs. Conclusions: This study reports the longest follow-up of endovascular treatment with nitinol stents in femoropopliteal TASC II C and D lesions. The results emphasize the feasibility of an endovascular-first strategy, even in lesions beyond 30 cm in length, and clarify its acceptable long-term durability and good clinical outcomes. Large multicenter RCTs with mid- and long-term follow-up are needed to investigate the role of different endovascular techniques in long femoropopliteal lesions.
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- 2022
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15. Needle Penetration Simulation: Influence of Penetration Angle and Sample Stress on the Mechanical Behaviors of Polymers Applying a Cast Silicone and a 3D-Printed Resin
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Thore von Steuben, Florian K. Enzmann, Sebastian Spintzyk, Frank Rupp, and Ariadne Roehler
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needle penetration ,3D printing ,mechanical properties ,material testing ,injection angle ,vessel wall stress ,Technology ,Electrical engineering. Electronics. Nuclear engineering ,TK1-9971 ,Engineering (General). Civil engineering (General) ,TA1-2040 ,Microscopy ,QH201-278.5 ,Descriptive and experimental mechanics ,QC120-168.85 - Abstract
For surgical catheterization training applications, realistic and effective materials are desired. In this study, the relevance of a needle puncture angle and a simulated wall stress on different elastic materials were determined in a previously developed experimental setup. Both settings were considered individually in two new setups. In addition, a control setup with neither angle nor prestress was designed. During the process of puncturing the samples of two materials (Replisil 9N and Formlabs Elastic 50A), force–displacement values were collected, and three predefined parameters evaluated. The differences between the angled/stressed groups and the control group were analyzed. The additively processed material required a significantly higher force to puncture than the conventional one (p < 0.001). Moreover, a needle angulation of 45° required more force than puncturing orthogonally. Prestressing the samples did not clearly influence the resulting force. An evaluation of relative parameters showed that the investigated materials behaved differently but not linearly differently under the influence of needle angle and prestress. Therefore, it is essential to evaluate the properties and suitability of materials for surgical training models in appropriate experimental setups considering multiple parameters.
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- 2022
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16. The Role of Telocytes and Telocyte-Derived Exosomes in the Development of Thoracic Aortic Aneurysm
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Thomas Aschacher, Olivia Aschacher, Katy Schmidt, Florian K. Enzmann, Eva Eichmair, Bernhard Winkler, Zsuzsanna Arnold, Felix Nagel, Bruno K. Podesser, Andreas Mitterbauer, Barbara Messner, Martin Grabenwöger, Günther Laufer, Marek P. Ehrlich, and Michael Bergmann
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telocytes ,aorta ,thoracic ascending aortic aneurysms ,exosomes ,cellular senescence ,miRNA ,Biology (General) ,QH301-705.5 ,Chemistry ,QD1-999 - Abstract
A hallmark of thoracic aortic aneurysms (TAA) is the degenerative remodeling of aortic wall, which leads to progressive aortic dilatation and resulting in an increased risk for aortic dissection or rupture. Telocytes (TCs), a distinct type of interstitial cells described in many tissues and organs, were recently observed in the aortic wall, and studies showed the potential regulation of smooth muscle cell (SMC) homeostasis by TC-released shed vesicles. The purpose of the present work was to study the functions of TCs in medial degeneration of TAA. During aneurysmal formation an increase of aortic TCs was identified in human surgical specimens of TAA-patients, compared to healthy thoracic aortic (HTA)-tissue. We found the presence of epithelial progenitor cells in the adventitial layer, which showed increased infiltration in TAA samples. For functional analysis, HTA- and TAA-telocytes were isolated, characterized, and compared by their protein levels, mRNA- and miRNA-expression profiles. We detected TC and TC-released exosomes near SMCs. TAA-TC-exosomes showed a significant increase of the SMC-related dedifferentiation markers KLF-4-, VEGF-A-, and PDGF-A-protein levels, as well as miRNA-expression levels of miR-146a, miR-221 and miR-222. SMCs treated with TAA-TC-exosomes developed a dedifferentiation-phenotype. In conclusion, the study shows for the first time that TCs are involved in development of TAA and could play a crucial role in SMC phenotype switching by release of extracellular vesicles.
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- 2022
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17. Structures of immature EIAV Gag lattices reveal a conserved role for IP6 in lentivirus assembly.
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Robert A Dick, Chaoyi Xu, Dustin R Morado, Vladyslav Kravchuk, Clifton L Ricana, Terri D Lyddon, Arianna M Broad, J Ryan Feathers, Marc C Johnson, Volker M Vogt, Juan R Perilla, John A G Briggs, and Florian K M Schur
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Immunologic diseases. Allergy ,RC581-607 ,Biology (General) ,QH301-705.5 - Abstract
Retrovirus assembly is driven by the multidomain structural protein Gag. Interactions between the capsid domains (CA) of Gag result in Gag multimerization, leading to an immature virus particle that is formed by a protein lattice based on dimeric, trimeric, and hexameric protein contacts. Among retroviruses the inter- and intra-hexamer contacts differ, especially in the N-terminal sub-domain of CA (CANTD). For HIV-1 the cellular molecule inositol hexakisphosphate (IP6) interacts with and stabilizes the immature hexamer, and is required for production of infectious virus particles. We have used in vitro assembly, cryo-electron tomography and subtomogram averaging, atomistic molecular dynamics simulations and mutational analyses to study the HIV-related lentivirus equine infectious anemia virus (EIAV). In particular, we sought to understand the structural conservation of the immature lentivirus lattice and the role of IP6 in EIAV assembly. Similar to HIV-1, IP6 strongly promoted in vitro assembly of EIAV Gag proteins into virus-like particles (VLPs), which took three morphologically highly distinct forms: narrow tubes, wide tubes, and spheres. Structural characterization of these VLPs to sub-4Å resolution unexpectedly showed that all three morphologies are based on an immature lattice with preserved key structural components, highlighting the structural versatility of CA to form immature assemblies. A direct comparison between EIAV and HIV revealed that both lentiviruses maintain similar immature interfaces, which are established by both conserved and non-conserved residues. In both EIAV and HIV-1, IP6 regulates immature assembly via conserved lysine residues within the CACTD and SP. Lastly, we demonstrate that IP6 stimulates in vitro assembly of immature particles of several other retroviruses in the lentivirus genus, suggesting a conserved role for IP6 in lentiviral assembly.
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- 2020
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18. Interpolation sets for dynamical systems
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Koutsogiannis, Andreas, Le, Anh N., Moreira, Joel, Pavlov, Ronnie, and Richter, Florian K.
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Mathematics - Dynamical Systems ,Primary: 37B05, Secondary: 37B10 - Abstract
Originating in harmonic analysis, interpolation sets were first studied in dynamics by Glasner and Weiss in the 1980s. A set $S \subset \mathbb{N}$ is an interpolation set for a class of topological dynamical systems $\mathcal{C}$ if any bounded sequence on $S$ can be extended to a sequence that arises from a system in $\mathcal{C}$. In this paper, we provide combinatorial characterizations of interpolation sets for: $\bullet$ (totally) minimal systems; $\bullet$ topologically (weak) mixing systems; $\bullet$ strictly ergodic systems; and $\bullet$ zero entropy systems. Additionally, we prove some results on a slightly different notion, called weak interpolation sets, for several classes of systems. We also answer a question of Host, Kra, and Maass concerning the connection between sets of pointwise recurrence for distal systems and $IP$-sets., Comment: 31 pages, to appear in Trans. Amer. Math. Soc
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- 2024
19. Problems on infinite sumset configurations in the integers and beyond
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Kra, Bryna, Moreira, Joel, Richter, Florian K., and Robertson, Donald
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Mathematics - Combinatorics ,Mathematics - Number Theory ,05D10, 11B13, 11B30, 05-02, 11-02, 00A27, 37A05 - Abstract
In contrast to finite arithmetic configurations, relatively little is known about which infinite patterns can be found in every set of natural numbers with positive density. Building on recent advances showing infinite sumsets can be found, we explore numerous open problems and obstructions to finding other infinite configurations in every set of natural numbers with positive density., Comment: 37 pages
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- 2023
20. A Structural Perspective of the Role of IP6 in Immature and Mature Retroviral Assembly
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Martin Obr, Florian K. M. Schur, and Robert A. Dick
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HIV ,inositol hexakisphosphate ,orthoretrovirus ,Gag ,Microbiology ,QR1-502 - Abstract
The small cellular molecule inositol hexakisphosphate (IP6) has been known for ~20 years to promote the in vitro assembly of HIV-1 into immature virus-like particles. However, the molecular details underlying this effect have been determined only recently, with the identification of the IP6 binding site in the immature Gag lattice. IP6 also promotes formation of the mature capsid protein (CA) lattice via a second IP6 binding site, and enhances core stability, creating a favorable environment for reverse transcription. IP6 also enhances assembly of other retroviruses, from both the Lentivirus and the Alpharetrovirus genera. These findings suggest that IP6 may have a conserved function throughout the family Retroviridae. Here, we discuss the different steps in the viral life cycle that are influenced by IP6, and describe in detail how IP6 interacts with the immature and mature lattices of different retroviruses.
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- 2021
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21. Successful Insulin Glargine Treatment in Two Pet Guinea Pigs with Suspected Type 1 Diabetes Mellitus
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Theresa Kreilmeier-Berger, Florian K. Zeugswetter, Klaas-Ole Blohm, Ilse Schwendenwein, Elisabeth Baszler, Bernadette Ploderer, Iwan Anton Burgener, and Frank Künzel
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cataract ,insulin-dependent ,glucometer ,phacolytic anterior uveitis ,Veterinary medicine ,SF600-1100 ,Zoology ,QL1-991 - Abstract
Scientific information on spontaneous type I diabetes mellitus (DM) and treatment modalities in guinea pigs is scarce. As most diabetic guinea pigs are overweight and respond to dietary changes, a disorder resembling type II-DM in humans seems to be most prevalent in this species. In the present report, a nine-month-old female intact guinea pig (GP1) was presented because of a cataract and polyphagia. The physical examinations in GP1 and its littermate, GP2, were unremarkable. Laboratory tests revealed hyperglycemia, hyperlipidemia, elevated fructosamine concentrations, and glucosuria in GP1 and GP2. Not responding to dietary changes, an insulin-dependent diabetes mellitus was suspected in both animals. Treatment with 0.5 IU of glargine insulin (Lantus®) per guinea pig subcutaneously (s.c.) once daily was initiated in both animals. Monitoring included repeated clinical evaluations and the measurement of plasma glucose and fructosamine concentrations. Capillary glucose concentration was measured using a glucometer, and glucosuria was monitored by dipstick. Blood glucose concentrations decreased quickly in both GPs, and glucosuria resolved. Including several dose adjustments, DM remained controlled for over 1.5 years. Bilateral cataracts and lens-induced uveitis in GP1 were medically managed with only slight progression. This is the first report of guinea pigs with insulin-dependent diabetes mellitus that were successfully treated with long-acting basal insulin glargine.
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- 2021
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22. Single-electron occupation in quantum dot arrays at selectable plunger gate voltage
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Meyer, Marcel, Déprez, Corentin, Meijer, Ilja N., Unseld, Florian K., Karwal, Saurabh, Sammak, Amir, Scappucci, Giordano, Vandersypen, Lieven M. K., and Veldhorst, Menno
- Subjects
Condensed Matter - Mesoscale and Nanoscale Physics ,Quantum Physics - Abstract
The small footprint of semiconductor qubits is favourable for scalable quantum computing. However, their size also makes them sensitive to their local environment and variations in gate structure. Currently, each device requires tailored gate voltages to confine a single charge per quantum dot, clearly challenging scalability. Here, we tune these gate voltages and equalize them solely through the temporary application of stress voltages. In a double quantum dot, we reach a stable (1,1) charge state at identical and predetermined plunger gate voltage and for various interdot couplings. Applying our findings, we tune a 2$\times$2 quadruple quantum dot such that the (1,1,1,1) charge state is reached when all plunger gates are set to 1 V. The ability to define required gate voltages may relax requirements on control electronics and operations for spin qubit devices, providing means to advance quantum hardware.
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- 2023
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23. STAT5 is Expressed in CD34+/CD38− Stem Cells and Serves as a Potential Molecular Target in Ph-Negative Myeloproliferative Neoplasms
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Emir Hadzijusufovic, Alexandra Keller, Daniela Berger, Georg Greiner, Bettina Wingelhofer, Nadine Witzeneder, Daniel Ivanov, Emmanuel Pecnard, Harini Nivarthi, Florian K. M. Schur, Yüksel Filik, Christoph Kornauth, Heidi A. Neubauer, Leonhard Müllauer, Gary Tin, Jisung Park, Elvin D. de Araujo, Patrick T. Gunning, Gregor Hoermann, Fabrice Gouilleux, Robert Kralovics, Richard Moriggl, and Peter Valent
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MPN ,STAT5 ,JAK2 V617F ,neoplastic stem cells ,Neoplasms. Tumors. Oncology. Including cancer and carcinogens ,RC254-282 - Abstract
Janus kinase 2 (JAK2) and signal transducer and activator of transcription-5 (STAT5) play a key role in the pathogenesis of myeloproliferative neoplasms (MPN). In most patients, JAK2 V617F or CALR mutations are found and lead to activation of various downstream signaling cascades and molecules, including STAT5. We examined the presence and distribution of phosphorylated (p) STAT5 in neoplastic cells in patients with MPN, including polycythemia vera (PV, n = 10), essential thrombocythemia (ET, n = 15) and primary myelofibrosis (PMF, n = 9), and in the JAK2 V617F-positive cell lines HEL and SET-2. As assessed by immunohistochemistry, MPN cells displayed pSTAT5 in all patients examined. Phosphorylated STAT5 was also detected in putative CD34+/CD38− MPN stem cells (MPN-SC) by flow cytometry. Immunostaining experiments and Western blotting demonstrated pSTAT5 expression in both the cytoplasmic and nuclear compartment of MPN cells. Confirming previous studies, we also found that JAK2-targeting drugs counteract the expression of pSTAT5 and growth in HEL and SET-2 cells. Growth-inhibition of MPN cells was also induced by the STAT5-targeting drugs piceatannol, pimozide, AC-3-019 and AC-4-130. Together, we show that CD34+/CD38− MPN-SC express pSTAT5 and that pSTAT5 is expressed in the nuclear and cytoplasmic compartment of MPN cells. Whether direct targeting of pSTAT5 in MPN-SC is efficacious in MPN patients remains unknown.
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- 2020
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24. On the maximal spectral type of nilsystems
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Ackelsberg, Ethan, Richter, Florian K., and Shalom, Or
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Mathematics - Dynamical Systems - Abstract
Let $(G/\Gamma,R_a)$ be an ergodic $k$-step nilsystem for $k\geq 2$. We adapt an argument of Parry to show that $L^2(G/\Gamma)$ decomposes as a sum of a subspace with discrete spectrum and a subspace of Lebesgue spectrum with infinite multiplicity. In particular, we generalize a result previously established by Host, Kra and Maass for $2$-step nilsystems and a result by Stepin for nilsystems $G/\Gamma$ with connected, simply connected $G$., Comment: 12 pages
- Published
- 2023
25. A 2D quantum dot array in planar $^{28}$Si/SiGe
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Unseld, Florian K., Meyer, Marcel, Mądzik, Mateusz T., Borsoi, Francesco, de Snoo, Sander L., Amitonov, Sergey V., Sammak, Amir, Scappucci, Giordano, Veldhorst, Menno, and Vandersypen, Lieven M. K.
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Condensed Matter - Mesoscale and Nanoscale Physics ,Quantum Physics - Abstract
Semiconductor spin qubits have gained increasing attention as a possible platform to host a fault-tolerant quantum computer. First demonstrations of spin qubit arrays have been shown in a wide variety of semiconductor materials. The highest performance for spin qubit logic has been realized in silicon, but scaling silicon quantum dot arrays in two dimensions has proven to be challenging. By taking advantage of high-quality heterostructures and carefully designed gate patterns, we are able to form a tunnel coupled 2 $\times$ 2 quantum dot array in a $^{28}$Si/SiGe heterostructure. We are able to load a single electron in all four quantum dots, thus reaching the (1,1,1,1) charge state. Furthermore we characterise and control the tunnel coupling between all pairs of dots by measuring polarisation lines over a wide range of barrier gate voltages. Tunnel couplings can be tuned from about $30~\rm \mu eV$ up to approximately $400~\rm \mu eV$. These experiments provide a first step toward the operation of spin qubits in $^{28}$Si/SiGe quantum dots in two dimensions., Comment: 8 pages, 6 figures
- Published
- 2023
26. A proof of Erd\H{o}s's $B+B+t$ conjecture
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Kra, Bryna, Moreira, Joel, Richter, Florian K., and Robertson, Donald
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Mathematics - Dynamical Systems ,Mathematics - Combinatorics ,Mathematics - Number Theory ,05D10, 11B13, 37A05, 11B30 - Abstract
We show that every set $A$ of natural numbers with positive upper density can be shifted to contain the restricted sumset $\{b_1 + b_2 : b_1, b_2\in B \text{ and } b_1 \neq b_2 \}$ for some infinite set $B \subset A$., Comment: 14 pages. Changes after referee comments, improved exposition
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- 2022
27. Infinite Sumsets in Sets with Positive Density
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Kra, Bryna, Moreira, Joel, Richter, Florian K., and Robertson, Donald
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Mathematics - Dynamical Systems ,Mathematics - Combinatorics ,Mathematics - Number Theory ,05D10 11B13 37A05 11B30 - Abstract
Motivated by questions asked by Erdos, we prove that any set $A\subset{\mathbb N}$ with positive upper density contains, for any $k\in{\mathbb N}$, a sumset $B_1+\cdots+B_k$, where $B_1,\dots,B_k\subset{\mathbb N}$ are infinite. Our proof uses ergodic theory and relies on structural results for measure preserving systems. Our techniques are new, even for the previously known case of $k=2$., Comment: 49 Pages
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- 2022
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28. Changing collective action: Nudges and team decisions.
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Florian K. Diekert and Tillmann Eymess
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- 2024
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29. Masking efficacy of bleaching and/ or resin infiltration of fluorotic spots on anterior teeth - a systematic review and meta-analysis
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Wittich, Florian K., Cebula, Marcus, Effenberger, Susanne, Schoppmeier, Christoph M., Schwendicke, Falk, Barbe, Anna Greta, and Wicht, Michael J.
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- 2024
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30. Tailoring the band structure of plexcitonic crystals by strong coupling
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Davoodi, Fatemeh, Taleb, Masoud, Diekmann, Florian K., Coenen, Toon, Rossnagel, Kai, and Talebi, Nahid
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Physics - Optics ,Condensed Matter - Mesoscale and Nanoscale Physics - Abstract
Transition-metal dichalcogenides with their exciton-dominated optical behavior emerge as promising materials for realizing strong light-matter interactions in the visible range and at ambient conditions. When these materials are combined with metals, the energy confining ability of plasmon polaritons in metals below the diffraction limit, allows for further enhancing and tailoring the light-matter interaction, due to the formation of plexcitons in hybrid metal-TMDC structures at the interface. Herein, we demonstrate that the coupling between quasi-propagating plasmons in plasmonic crystals and excitons in WSe2, provides a multi-oscillator playground for tailoring the band structure of plasmonic crystal structures and results in emerging flat bands. The cathodoluminescence spectroscopy and angle-resolved measurements combined with the numerically calculated photonic band structure confirm a strong exciton-plasmon coupling, leading to significant changes in the band diagram of the hybrid lattice and the ability to tailor the band diagram via strong coupling. The hybrid plexcitonic crystal structures investigated here sustain optical waves with remarkably low group velocities. These results could be used for designing tunable slow-light structures based on the strong-coupling effect and pave the way toward plexcitonic topological photonic structures.
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- 2022
31. Virus-specific immune response in HBeAg-negative chronic hepatitis B: relationship with clinical profile and HBsAg serum levels.
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Elisabetta Loggi, Florian K Bihl, Carmela Cursaro, Camilla Granieri, Silvia Galli, Lucia Brodosi, Giuliano Furlini, Mauro Bernardi, Christian Brander, and Pietro Andreone
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Medicine ,Science - Abstract
BACKGROUND AIMS: The immune impairment characterizing chronic hepatitis B (cHBV) infection is thought to be the consequence of persistent exposure to viral antigens. However, the immune correlates of different clinical stages of cHBV and their relation with different levels of HBsAg have not been investigated. The aim of the present study was to evaluate the relationship between HBV-specific T cells response and the degree of in vivo HBV control and HBsAg serum levels in HBeAg-HBeAb+ cHBV. METHODS: Peripheral blood mononuclear cells from 42 patients with different clinical profiles (treatment-suppressed, inactive carriers and active hepatitis) of cHBV, 6 patients with resolved HBV infection and 10 HBV-uninfected individuals were tested with overlapping peptides spanning the entire HBV proteome. The frequency and magnitude of HBV-specific T cell responses was assessed by IFNγ ELISPOT assay. Serum HBsAg was quantified with a chemiluminescent immunoassay. RESULTS: The total breadth and magnitude of HBV-specific T cell responses did not differ significantly between the four groups. However, inactive carriers targeted preferentially the core region. In untreated patients, the breadth of the anti-core specific T cell response was inversely correlated with serum HBsAg concentrations as well as HBV-DNA and ALT levels and was significantly different in patients with HBsAg levels either above or below 1000 IU/mL. The same inverse association between anti-core T cell response and HBsAg levels was found in treated patients. CONCLUSIONS: Different clinical outcomes of cHBV infection are associated with the magnitude, breadth and specificity of the HBV-specific T cell response. Especially, robust anti-core T cell responses were found in the presence of reduced HBsAg serum levels, suggesting that core-specific T cell responses can mediate a protective effect on HBV control.
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- 2013
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32. Impact of loading phase, initial response and CFH genotype on the long-term outcome of treatment for neovascular age-related macular degeneration.
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Moreno Menghini, Barbara Kloeckener-Gruissem, Johannes Fleischhauer, Malaika M Kurz-Levin, Florian K P Sutter, Wolfgang Berger, and Daniel Barthelmes
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Medicine ,Science - Abstract
OBJECTIVE: Factors influencing the outcome of anti-VEGF treatment in neovascular AMD are still investigated. We analyzed the impact of a loading phase, the significance of an initial response for the long-term and the effect of the CFH polymorphism (p.His402Tyr) on treatment outcome. METHODS: Patients treated with ranibizumab for neovascular AMD were analyzed over a period of 24 months by assessing effects of loading phase, initial response and genotype of CFH rs1061170 (c.1204C>T, p.His402Tyr). RESULTS: 204 eyes were included. A change of +5.0 [-1;+11] letters and +1.5 [-5.5;+9.5] was observed with a median of 4 [3]; [7] and 10 [7]; [14] ranibizumab injections during 12 and 24 months, respectively. Loading phase was no significant predictor for treatment as VA outcome in eyes with and without loading phase was similar (p = 0.846 and p = 0.729) at 12 and 24 months. In contrast, initial response was a significant predictor for improving vision of 5 or more letters at 12 (p = 0.001; OR = 6.75) and 24 months (p = 0.01; OR = 4.66). Furthermore, the CT genotype at CFH rs1061170 was identified as a significant predictor for a favorable VA outcome at 12 and 24 months (OR = 6.75, p = 0.001 and OR = 4.66, p = 0.01). CONCLUSIONS: Our data suggest that clinical decisions regarding treatment may be guided by observing patients' initial response as well as their genotype of SNP rs1061170, while the criterion of loading phase may not bear the customary value.
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- 2012
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33. The rise and fall of diapirs during thin-skinned extension revisited
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Schöpfer, Martin P.J. and Lehner, Florian K.
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- 2024
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34. Delayed appearance of high altitude retinal hemorrhages.
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Daniel Barthelmes, Martina M Bosch, Tobias M Merz, Benno L Petrig, Frederic Truffer, Konrad E Bloch, Timothy A Holmes, Philippe Cattin, Urs Hefti, Miriam Sellner, Florian K P Sutter, Marco Maggiorini, and Klara Landau
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Medicine ,Science - Abstract
BACKGROUND: Retinal hemorrhages have been described as a component of high altitude retinopathy (HAR) in association with altitude illness. In this prospective high altitude study, we aimed to gain new insights into the pathophysiology of HAR and explored whether HAR could be a valid early indicator of altitude illness. METHODOLOGY/PRINCIPAL FINDINGS: 28 mountaineers were randomly assigned to two ascent profiles during a research expedition to Mt. Muztagh Ata (7546 m/24,751 ft). Digital fundus photographs were taken prior to expedition at 490 m (1,607 ft), during expedition at 4497 m (14,750 ft = base camp), 5533 m (18,148 ft), 6265 m (20,549 ft), 6865 m (22,517 ft) and 4.5 months thereafter at 490 m. Number, size and time of occurrence of hemorrhages were recorded. Oxygen saturation (SpO₂) and hematocrit were also assessed. 79% of all climbers exhibited retinal hemorrhages during the expedition. Number and area of retinal bleeding increased moderately to medium altitudes (6265 m). Most retinal hemorrhages were detected after return to base camp from a high altitude. No post-expeditional ophthalmic sequelae were detected. Significant negative (SpO₂ Beta: -0.4, p
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- 2011
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35. Multiple ergodic averages along functions from a Hardy field: Convergence, recurrence and combinatorial applications
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Bergelson, Vitaly, Moreira, Joel, and Richter, Florian K.
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- 2024
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36. HIV patients developing primary CNS lymphoma lack EBV-specific CD4+ T cell function irrespective of absolute CD4+ T cell counts.
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Olivier Gasser, Florian K Bihl, Marcel Wolbers, Elisabetta Loggi, Ingrid Steffen, Hans H Hirsch, Huldrych F Günthard, Bruce D Walker, Christian Brander, Manuel Battegay, Christoph Hess, and Swiss HIV Cohort Study
- Subjects
Medicine - Abstract
BACKGROUND: In chronic HIV infection, antiretroviral therapy-induced normalization of CD4(+) T cell counts (immune reconstitution [IR]) is associated with a decreased incidence of opportunistic diseases. However, some individuals remain at risk for opportunistic diseases despite prolonged normalization of CD4(+) T cell counts. Deficient Epstein-Barr virus (EBV)-specific CD4(+) T cell function may explain the occurrence of EBV-associated opportunistic malignancy-such as primary central nervous system (PCNS) lymphoma-despite recovery of absolute CD4(+) T cell counts. METHODS AND FINDINGS: Absolute CD4(+) T cell counts and EBV-specific CD4(+) T cell-dependent interferon-gamma production were assessed in six HIV-positive individuals prior to development of PCNS lymphoma ("cases"), and these values were compared with those in 16 HIV-infected matched participants with no sign of EBV-associated pathology ("matched controls") and 11 nonmatched HIV-negative blood donors. Half of the PCNS lymphoma patients fulfilled IR criteria (defined here as CD4(+) T cell counts >or=500/microl blood). EBV-specific CD4(+) T cells were assessed 0.5-4.7 y prior to diagnosis of lymphoma. In 0/6 cases versus 13/16 matched controls an EBV-specific CD4(+) T cell response was detected (p = 0.007; confidence interval for odds ratio [0-0.40]). PCNS lymphoma patients also differed with regards to this response significantly from HIV-negative blood donors (p < 0.001, confidence interval for odds ratio [0-0.14]), but there was no evidence for a difference between HIV-negative participants and the HIV-positive matched controls (p = 0.47). CONCLUSIONS: Irrespective of absolute CD4(+) T cell counts, HIV-positive patients who subsequently developed PCNS lymphoma lacked EBV-specific CD4(+) T cell function. Larger, ideally prospective studies are needed to confirm these preliminary data, and clarify the impact of pathogen-specific versus surrogate marker-based assessment of IR on clinical outcome.
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- 2007
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37. A combinatorial proof of a sumset conjecture of Furstenberg
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Glasscock, Daniel, Moreira, Joel, and Richter, Florian K.
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Mathematics - Combinatorics ,Mathematics - Number Theory - Abstract
We give a new proof of a sumset conjecture of Furstenberg that was first proved by Hochman and Shmerkin in 2012: if $\log r / \log s$ is irrational and $X$ and $Y$ are $\times r$- and $\times s$-invariant subsets of $[0,1]$, respectively, then $\dim_\text{H} (X+Y) = \min ( 1, \dim_\text{H} X + \dim_\text{H} Y)$. Our main result yields information on the size of the sumset $\lambda X + \eta Y$ uniformly across a compact set of parameters at fixed scales. The proof is combinatorial and avoids the machinery of local entropy averages and CP-processes, relying instead on a quantitative, discrete Marstrand projection theorem and a subtree regularity theorem that may be of independent interest., Comment: 26 pages. Some of this work was originally posted to the arXiv in the first half of the paper "Additive transversality of fractal sets in the reals and the integers" (arXiv:2007.05480v1); that paper has since been updated (arXiv:2007.05480) and no longer includes any of this work
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- 2021
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38. On Katznelson's Question for skew product systems
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Glasscock, Daniel, Koutsogiannis, Andreas, and Richter, Florian K.
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Mathematics - Dynamical Systems ,Mathematics - Combinatorics ,37B05, 37B20, 05B10 - Abstract
Katznelson's Question is a long-standing open question concerning recurrence in topological dynamics with strong historical and mathematical ties to open problems in combinatorics and harmonic analysis. In this article, we give a positive answer to Katznelson's Question for certain towers of skew product extensions of equicontinuous systems, including systems of the form $(x,t) \mapsto (x + \alpha, t + h(x))$. We describe which frequencies must be controlled for in order to ensure recurrence in such systems, and we derive combinatorial corollaries concerning the difference sets of syndetic subsets of the natural numbers., Comment: 38 pages, revised version; the statement of Theorem C has become more general addressing the case in which a higher-order derivative of the sequence f is almost periodic. To appear in BAMS
- Published
- 2021
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39. A combinatorial proof of a sumset conjecture of Furstenberg
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Glasscock, Daniel, Moreira, Joel, and Richter, Florian K.
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- 2023
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40. Uniform distribution in nilmanifolds along functions from a Hardy field
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Richter, Florian K.
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- 2023
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41. Pragmatic, constructive, and reconstructive memory influences on the hindsight bias
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Salmen, Karolin, Ermark, Florian K. G., and Fiedler, Klaus
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- 2023
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42. Additive and geometric transversality of fractal sets in the integers
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Glasscock, Daniel, Moreira, Joel, and Richter, Florian K.
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Mathematics - Number Theory ,Mathematics - Dynamical Systems ,11A63, 37C45, 28A80, 11K55 - Abstract
By juxtaposing ideas from fractal geometry and dynamical systems, Furstenberg proposed a series of conjectures in the late 1960's that explore the relationship between digit expansions with respect to multiplicatively independent bases. In this work, we introduce and study - in the discrete context of the integers - analogues of some of the notions and results surrounding Furstenberg's work. In particular, we define a new class of fractal sets of integers that parallels the notion of $\times r$-invariant sets on the 1-torus and investigate the additive and geometric independence between two such fractal sets when they are structured with respect to multiplicatively independent bases. Our main results in this direction parallel the works of Furstenberg, Hochman-Shmerkin, Shmerkin, Wu, and Lindenstrauss-Meiri-Peres and include: -a classification of all subsets of the positive integers that are simultaneously $\times r$- and $\times s$-invariant; -integer analogues of two of Furstenberg's transversality conjectures pertaining to the dimensions of the intersection $A\cap B$ and the sumset $A+B$ of $\times r$- and $\times s$-invariant sets $A$ and $B$ when $r$ and $s$ are multiplicatively independent; and -a description of the dimension of iterated sumsets $A+A+\cdots+A$ for any $\times r$-invariant set $A$. We achieve these results by combining ideas from fractal geometry and ergodic theory to build a bridge between the continuous and discrete regimes. For the transversality results, we rely heavily on quantitative bounds on the $L^q$-dimensions of projections of restricted digit Cantor measures obtained recently by Shmerkin. We end by outlining a number of open questions and directions regarding fractal subsets of the integers., Comment: 51 pages
- Published
- 2020
43. Multiple ergodic averages along functions from a Hardy field: convergence, recurrence and combinatorial applications
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Bergelson, Vitaly, Moreira, Joel, and Richter, Florian K.
- Subjects
Mathematics - Dynamical Systems ,Mathematics - Combinatorics ,37A44, 28D05, 05D10, 11B30 - Abstract
We obtain new results pertaining to convergence and recurrence of multiple ergodic averages along functions from a Hardy field. Among other things, we confirm some of the conjectures posed by Frantzikinakis in [Fra10; Fra16] and obtain combinatorial applications which contain, as rather special cases, several previously known (polynomial and non-polynomial) extensions of Szemeredi's theorem on arithmetic progressions [BL96; BLL08; FW09; Fra10; BMR17]. One of the novel features of our results, which is not present in previous work, is that they allow for a mixture of polynomials and non-polynomial functions. As an illustration, assume $f_i(t)=a_{i,1}t^{c_{i,1}}+\cdots+a_{i,d}t^{c_{i,d}}$ for $c_{i,j}>0$ and $a_{i,j}\in\mathbb{R}$. Then $\bullet$ for any measure preserving system $(X,{\mathcal B},\mu,T)$ and $h_1,\dots,h_k\in L^\infty(X)$, the limit $$\lim_{N\to\infty}\frac{1}{N}\sum_{n=1}^N T^{[f_1(n)]}h_1\cdots T^{[f_k(n)]}h_k$$ exists in $L^2$; $\bullet$ for any $E\subset \mathbb{N}$ with $\overline{\mathrm{d}}(E)>0$ there are $a,n\in\mathbb{N}$ such that $\{a,\, a+[f_1(n)],\ldots,a+[f_k(n)]\}\subset E$. We also show that if $f_1,\dots,f_k$ belong to a Hardy field, have polynomial growth, and are such that no linear combination of them is a polynomial, then for any measure preserving system $(X,{\mathcal B},\mu,T)$ and any $A\in{\mathcal B}$, $$\limsup_{N\to\infty}\frac{1}{N}\sum_{n=1}^N\mu\Big(A\cap T^{-[ f_1(n) ]}A\cap\ldots\cap T^{-[f_k(n)]}A\Big)\,\geq\,\mu(A)^{k+1}.$$, Comment: 41 pages, 2nd revised version implementing referee comments
- Published
- 2020
44. Uniform distribution in nilmanifolds along functions from a Hardy field
- Author
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Richter, Florian K.
- Subjects
Mathematics - Dynamical Systems - Abstract
We study equidistribution properties of translations on nilmanifolds along functions of polynomial growth from a Hardy field. More precisely, if $X=G/\Gamma$ is a nilmanifold, $a_1,\ldots,a_k\in G$ are commuting nilrotations, and $f_1,\ldots,f_k$ are functions of polynomial growth from a Hardy field then we show that $\bullet$ the distribution of the sequence $a_1^{f_1(n)}\cdot\ldots\cdot a_k^{f_k(n)}\Gamma$ is governed by its projection onto the maximal factor torus, which extends Leibman's Equidistribution Criterion form polynomials to a much wider range of functions; and $\bullet$ the orbit closure of $a_1^{f_1(n)}\cdot\ldots\cdot a_k^{f_k(n)}\Gamma$ is always a finite union of sub-nilmanifolds, which extends some of the previous work of Leibman and Frantzikinakis on this topic., Comment: 49 pages, 2nd revised version after referee comments
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- 2020
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45. Structure of multicorrelation sequences with integer part polynomial iterates along primes
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Koutsogiannis, Andreas, Le, Anh N., Moreira, Joel, and Richter, Florian K.
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Mathematics - Dynamical Systems ,Mathematics - Number Theory ,(Primary)37A44, 37A15 (Secondary): 11B30 - Abstract
Let $T$ be a measure preserving $\mathbb{Z}^\ell$-action on the probability space $(X,{\mathcal B},\mu),$ $q_1,\dots,q_m:{\mathbb R}\to{\mathbb R}^\ell$ vector polynomials, and $f_0,\dots,f_m\in L^\infty(X)$. For any $\epsilon > 0$ and multicorrelation sequences of the form $\displaystyle\alpha(n)=\int_Xf_0\cdot T^{ \lfloor q_1(n) \rfloor }f_1\cdots T^{ \lfloor q_m(n) \rfloor }f_m\;d\mu$ we show that there exists a nilsequence $\psi$ for which $\displaystyle\lim_{N - M \to \infty} \frac{1}{N-M} \sum_{n=M}^{N-1} |\alpha(n) - \psi(n)| \leq \epsilon$ and $\displaystyle\lim_{N \to \infty} \frac{1}{\pi(N)} \sum_{p \in {\mathbb P}\cap[1,N]} |\alpha(p) - \psi(p)| \leq \epsilon.$ This result simultaneously generalizes previous results of Frantzikinakis [2] and the authors [11,13]., Comment: 7 pages
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- 2020
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46. Dynamical generalizations of the Prime Number Theorem and disjointness of additive and multiplicative semigroup actions
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Bergelson, Vitaly and Richter, Florian K.
- Subjects
Mathematics - Dynamical Systems ,Mathematics - Number Theory ,37A45, 11N99, 11J71 - Abstract
We establish two ergodic theorems which have among their corollaries numerous classical results from multiplicative number theory, including the Prime Number Theorem, a theorem of Pillai-Selberg, a theorem of Erd\H{o}s-Delange, the mean value theorem of Wirsing, and special cases of the mean value theorem of Hal\'asz. By building on the ideas behind our ergodic results, we recast Sarnak's M\"obius disjointness conjecture in a new dynamical framework. This naturally leads to an extension of Sarnak's conjecture which focuses on the disjointness of additive and multiplicative semigroup actions. We substantiate this extension by providing proofs of several special cases., Comment: 56 pages, implemented changes following the referees comments
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- 2020
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47. A new elementary proof of the Prime Number Theorem
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Richter, Florian K.
- Subjects
Mathematics - Number Theory ,11N05, 11A41 - Abstract
Let $\Omega(n)$ denote the number of prime factors of $n$. We show that for any bounded $f\colon\mathbb{N}\to\mathbb{C}$ one has \[ \frac{1}{N}\sum_{n=1}^N\, f(\Omega(n)+1)=\frac{1}{N}\sum_{n=1}^N\, f(\Omega(n))+\mathrm{o}_{N\to\infty}(1). \] This yields a new elementary proof of the Prime Number Theorem., Comment: 13 pages; to appear in Bulletin of the London Mathematical Society; corrected a small mistake in the proof of Proposition 2.2, see footnote 2 at the bottom of page 10
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- 2020
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48. A decomposition of multicorrelation sequences for commuting transformations along primes
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Le, Anh N., Moreira, Joel, and Richter, Florian K.
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Mathematics - Dynamical Systems - Abstract
We study multicorrelation sequences arising from systems with commuting transformations. Our main result is a refinement of a decomposition result of Frantzikinakis and it states that any multicorrelation sequences for commuting transformations can be decomposed, for every $\epsilon>0$, as the sum of a nilsequence $\phi(n)$ and a sequence $\omega(n)$ satisfying $\lim_{N\to\infty}\frac{1}{N}\sum_{n=1}^N |\omega(n)|<\epsilon$ and $\lim_{N\to\infty}\frac{1}{|\mathbb{P}\cap [N]|}\sum_{p\in \mathbb{P}\cap [N]} |\omega(p)|<\epsilon$., Comment: 27 pages
- Published
- 2020
- Full Text
- View/download PDF
49. Poly(glycolide) multi-arm star polymers: Improved solubility via limited arm length
- Author
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Florian K. Wolf, Anna M. Fischer, and Holger Frey
- Subjects
block copolymer ,hyperbranched ,PGA ,polyester ,polyglycerol ,poly(glycolide) ,star polymer ,Science ,Organic chemistry ,QD241-441 - Abstract
Due to the low solubility of poly(glycolic acid) (PGA), its use is generally limited to the synthesis of random copolyesters with other hydroxy acids, such as lactic acid, or to applications that permit direct processing from the polymer melt. Insolubility is generally observed for PGA when the degree of polymerization exceeds 20. Here we present a strategy that allows the preparation of PGA-based multi-arm structures which significantly exceed the molecular weight of processable oligomeric linear PGA (
- Published
- 2010
- Full Text
- View/download PDF
50. MiMiCPy: An Efficient Toolkit for MiMiC-Based QM/MM Simulations.
- Author
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Bharath Raghavan, Florian K. Schackert, Andrea Levy, Sophia K. Johnson, Emiliano Ippoliti, Davide Mandelli, Jógvan Magnus Haugaard Olsen, Ursula Rothlisberger, and Paolo Carloni
- Published
- 2023
- Full Text
- View/download PDF
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