1,675 research outputs found

    Boundary interpolation for slice hyperholomorphic Schur functions

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    A boundary Nevanlinna-Pick interpolation problem is posed and solved in the quaternionic setting. Given nonnegative real numbers κ1,,κN\kappa_1, \ldots, \kappa_N, quaternions p1,,pNp_1, \ldots, p_N all of modulus 11, so that the 22-spheres determined by each point do not intersect and pu1p_u \neq 1 for u=1,,Nu = 1,\ldots, N, and quaternions s1,,sNs_1, \ldots, s_N, we wish to find a slice hyperholomorphic Schur function ss so that limr1r(0,1)s(rpu)=suforu=1,,N,\lim_{\substack{r\rightarrow 1\\ r\in(0,1)}} s(r p_u) = s_u\quad {\rm for} \quad u=1,\ldots, N, and limr1r(0,1)1s(rpu)su1rκu,foru=1,,N.\lim_{\substack{r\rightarrow 1\\ r\in(0,1)}}\frac{1-s(rp_u)\overline{s_u}}{1-r}\le\kappa_u,\quad {\rm for} \quad u=1,\ldots, N. Our arguments relies on the theory of slice hyperholomorphic functions and reproducing kernel Hilbert spaces

    Use of Skin Grafts in Free Flap Reconstruction

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    Longitudinal microstructural changes in 18 amygdala nuclei resonate with cortical circuits and phenomics.

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    The amygdala nuclei modulate distributed neural circuits that most likely evolved to respond to environmental threats and opportunities. So far, the specific role of unique amygdala nuclei in the context processing of salient environmental cues lacks adequate characterization across neural systems and over time. Here, we present amygdala nuclei morphometry and behavioral findings from longitudinal population data (>1400 subjects, age range 40-69 years, sampled 2-3 years apart): the UK Biobank offers exceptionally rich phenotyping along with brain morphology scans. This allows us to quantify how 18 microanatomical amygdala subregions undergo plastic changes in tandem with coupled neural systems and delineating their associated phenome-wide profiles. In the context of population change, the basal, lateral, accessory basal, and paralaminar nuclei change in lockstep with the prefrontal cortex, a region that subserves planning and decision-making. The central, medial and cortical nuclei are structurally coupled with the insular and anterior-cingulate nodes of the salience network, in addition to the MT/V5, basal ganglia, and putamen, areas proposed to represent internal bodily states and mediate attention to environmental cues. The central nucleus and anterior amygdaloid area are longitudinally tied with the inferior parietal lobule, known for a role in bodily awareness and social attention. These population-level amygdala-brain plasticity regimes in turn are linked with unique collections of phenotypes, ranging from social status and employment to sleep habits and risk taking. The obtained structural plasticity findings motivate hypotheses about the specific functions of distinct amygdala nuclei in humans

    Vessel Ligation in Transoral Robotic Surgery: Survey of the American Head and Neck Society

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    Objectives: Hemorrhage after transoral robotic surgery (TORS) surgery ranges from minor self-limited bleeding to lethal complications. To decrease risk, several publications have suggested ligation of the external carotid artery or its branches, even though statistically it has not been shown to be effective. The current study anonymously surveyed members of American Head and Neck Society (AHNS) on how they manage vessel ligation in TORS for oncological indications to better understand this practice.Methods: AHNS sent an email invitation to members with 2 weekly follow-up emails. Participants anonymously completed 10 questions regarding how long they have performed TORS, how many cancer-related TORS they have performed both overall and within the past year, timing of neck dissection, ligation of vessels, and changes in their practice.Results: In total, 165 surveys were completed by AHNS surgeons. The average respondent had performed TORS for 3–5 years and performs \u3c20 of cases for oncological purposes per year. Of the respondents, 83.7% ligate vessels. The most frequent vessels ligated were the lingual artery (77.7%), facial artery (63.3%), ascending pharyngeal artery (30.1%), superior thyroid artery (13.3%), and external carotid artery (9%). The most common reason for surgeons to ligate vessels was that it was either learned during training (28.3%) or incorporated due to suggestion or discussion with peers (28.3). Additionally, 14% were found to ligate after experiences related to fatal or near fatal patient events. Conclusions: Prophylactic vessel ligation is a common practice among AHNS surgeons. Training or discussion with peers is the most common reason for vessel ligation given, with the lingual artery being the most commonly ligated. However, the choice of which vessel to be ligated remains controversial. Further investigation should focus on the different individual vessels that are ligated and the affect that has on complication rates.https://scholarlycommons.henryford.com/merf2019clinres/1066/thumbnail.jp

    Incorporating sensitive cardiac substructure sparing into radiation therapy planning

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    PURPOSE: Rising evidence suggests that cardiac substructures are highly radiosensitive. However, they are not routinely considered in treatment planning as they are not readily visualized on treatment planning CTs (TPCTs). This work integrated the soft tissue contrast provided by low-field MRIs acquired on an MR-linac via image registration to further enable cardiac substructure sparing on TPCTs. METHODS: Sixteen upper thoracic patients treated at various breathing states (7 end-exhalation, 7 end-inhalation, 2 free-breathing) on a 0.35T MR-linac were retrospectively evaluated. A hybrid MR/CT atlas and a deep learning three-dimensional (3D) U-Net propagated 13 substructures to TPCTs. Radiation oncologists revised contours using registered MRIs. Clinical treatment plans were re-optimized and evaluated for beam arrangement modifications to reduce substructure doses. Dosimetric assessment included mean and maximum (0.03cc) dose, left ventricular volume receiving 5Gy (LV-V5), and other clinical endpoints. As metrics of plan complexity, total MU and treatment time were evaluated between approaches. RESULTS: Cardiac sparing plans reduced the mean heart dose (mean reduction 0.7 ± 0.6, range 0.1 to 2.5 Gy). Re-optimized plans reduced left anterior descending artery (LADA) mean and LADA(0.03cc) (0.0-63.9% and 0.0 to 17.3 Gy, respectively). LV(0.03cc) was reduced by \u3e1.5 Gy for 10 patients while 6 cases had large reductions (\u3e7%) in LV-V5. Left atrial mean dose was equivalent/reduced in all sparing plans (mean reduction 0.9 ± 1.2 Gy). The left main coronary artery was better spared in all cases for mean dose and D(0.03cc) . One patient exhibited \u3e10 Gy reduction in D(0.03cc) to four substructures. There was no statistical difference in treatment time and MU, or clinical endpoints to the planning target volume, lung, esophagus, or spinal cord after re-optimization. Four patients benefited from new beam arrangements, leading to further dose reductions. CONCLUSIONS: By introducing 0.35T MRIs acquired on an MR-linac to verify cardiac substructure segmentations for CT-based treatment planning, an opportunity was presented for more effective sparing with limited increase in plan complexity. Validation in a larger cohort with appropriate margins offers potential to reduce radiation-related cardiotoxicities

    Sensitivity analysis and variance reduction in a stochastic NDT problem

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    In this paper, we present a framework to deal with uncertainty quantification in case where the ranges of variability of the random parameters are ill-known. Namely the physical properties of the corrosion product (magnetite) which frequently clogs the tube support plate of steam generator, which is inaccessible in nuclear power plants. The methodology is based on Polynomial Chaos (PC) for the direct approach and on Bayesian inference for the inverse approach. The direct Non-Intrusive Spectral Projection (NISP) method is first employed by considering prior probability densities and therefore constructing a PC surrogate model of the large-scale NDT finite element model. To face the prohibitive computational cost underlying the high dimensional random space, an adaptive sparse grid technique is applied on NISP resulting in drastic time reduction. The PC surrogate model, with reduced dimensionality, is used as a forward model in the Bayesian procedure. The posterior probability densities are then identified by inferring from few noisy experimental data. We demonstrate effectiveness of the approach by identifying the most influential parameter in the clogging detection as well as a variability range reduction

    Evidence supporting the use of peptides and peptidomimetics as potential SARS-CoV-2 (COVID-19) therapeutics

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    © 2020 Newlands Press. During a disease outbreak/pandemic situation such as COVID-19, researchers are in a prime position to identify and develop peptide-based therapies, which could be more rapidly and cost-effectively advanced into a clinical setting. One drawback of natural peptide drugs, however, is their proteolytic instability; peptidomimetics can help to overcome this caveat. In this review, we summarize peptide and peptide-based therapeutics that target one main entry pathway of SARS-CoV-2, which involves the host ACE2 receptor and viral spike (S) protein interaction. Furthermore, we discuss the advantages of peptidomimetics and other potential targets that have been studied using peptide-based therapeutics for COVID-19

    Update of alien fauna and new records from Tunisian marine waters

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    An updated inventory of alien marine fauna in coastal and offshore Tunisian waters is presented. Records were compiled from scientific and ‘grey’ publications, presentations at scientific meetings, theses presented in fulfillment of requirements towards MSc and PhD degrees, websites and personal observations. 136 alien species were recorded in Tunisian waters, 60 records in northern coasts, West Mediterranean and 76 in central and southern coasts, Central Mediterranean. Nearly half of the first sightings in Tunisian waters took place in the Gulf of Gabès. The dominant taxa are Crustancean (24%), Molluscs (23%), Fishes (19%) and Annelida (13%). Twenty one species previously reported as aliens, were upon consideration, reclassified as range-expanding Atlantic species. Amathia verticillata, previously considered native to the Mediterranean, is reclassified as pseudoindigenous. Twenty one alien species are newly recorded from Tunisia, including 5 fish species, 5 polychaetes, 4 crustaceans, 4 molluscs, and one each schyphozoan, bryozoan and tunicate. The findings of Gibberulus gibberulus albus, Morula aspera and Calcinus latens, three species new to the Mediterranean, and of Actaedoes tomentosus, reported for the second time in the basin, are described. Species were classified according to their establishment status and their origins. This contribution highlights the dual origin of biological invasion in Tunisian waters (Red Sea and Atlantic), with slightly more species of Red Sea and Indo-Pacific origin (61,76%).  The impact of the alien species in Tunisian waters was discussed
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