578 research outputs found
Time-reversible Dynamical Systems for Turbulence
Dynamical Ensemble Equivalence between hydrodynamic dissipative equations and
suitable time-reversible dynamical systems has been investigated in a class of
dynamical systems for turbulence. The reversible dynamics is obtained from the
original dissipative equations by imposing a global constraint. We find that,
by increasing the input energy, the system changes from an equilibrium state to
a non-equilibrium stationary state in which an energy cascade, with the same
statistical properties of the original system, is clearly detected.Comment: 16 pages Latex, 4 PS figures, on press on J. Phy
Influence of Nanoparticle Size and Shape on Oligomer Formation of an Amyloidogenic Peptide
Understanding the influence of macromolecular crowding and nanoparticles on
the formation of in-register -sheets, the primary structural component
of amyloid fibrils, is a first step towards describing \emph{in vivo} protein
aggregation and interactions between synthetic materials and proteins. Using
all atom molecular simulations in implicit solvent we illustrate the effects of
nanoparticle size, shape, and volume fraction on oligomer formation of an
amyloidogenic peptide from the transthyretin protein. Surprisingly, we find
that inert spherical crowding particles destabilize in-register -sheets
formed by dimers while stabilizing -sheets comprised of trimers and
tetramers. As the radius of the nanoparticle increases crowding effects
decrease, implying smaller crowding particles have the largest influence on the
earliest amyloid species. We explain these results using a theory based on the
depletion effect. Finally, we show that spherocylindrical crowders destabilize
the ordered -sheet dimer to a greater extent than spherical crowders,
which underscores the influence of nanoparticle shape on protein aggregation
A possible mechanism for cold denaturation of proteins at high pressure
We study cold denaturation of proteins at high pressures. Using
multicanonical Monte Carlo simulations of a model protein in a water bath, we
investigate the effect of water density fluctuations on protein stability. We
find that above the pressure where water freezes to the dense ice phase
( kbar), the mechanism for cold denaturation with decreasing
temperature is the loss of local low-density water structure. We find our
results in agreement with data of bovine pancreatic ribonuclease A.Comment: 4 pages for double column and single space. 3 figures Added
references Changed conten
Giardia lamblia and respiratory allergies: a study of children from an urban area with a high incidence of protozoan infections
OBJECTIVES: There is a high incidence of intestinal parasite infection in urban areas in the Northeast of Brazil. Giardia lamblia infections have been associated with increased prevalence of cutaneous allergies and gastrointestinal disorders. However, little is known about the relationship between giardiasis and allergic diseases of the airways. The present study aimed to investigate the possible association between respiratory allergic diseases and infections by G. lamblia in children from urban areas. METHODS: This study recruited 110 patients of both sexes aged 5-15 years. Patients were administered a questionnaire evaluating clinical symptoms and were given skin tests, parasite tests and serum tests. RESULTS: A high incidence of G. lamblia was observed (45%, 50/110). Infections by this protozoan were not associated with increased risk of respiratory allergy (p = 0.075), high total IgE levels (p = 0.701), positive specific IgE tests (p = 0.250), or positive skin tests for a range of environmental allergens (p = 0.239). CONCLUSION: This study demonstrated that symptoms of asthma, skin allergy and serum markers were not associated with G. lamblia infections in this sample of children from urban areas.OBJETIVO: Uma elevada incidĆŖncia de enteroparasitoses Ć© encontrada em regiƵes urbanas do nordeste brasileiro. As infecƧƵes por Giardia lamblia tĆŖm sido relacionadas com aumento da prevalĆŖncia de alergias cutĆ¢neas e gastrointestinais. Contudo, ainda existe pouca informaĆ§Ć£o sobre a associaĆ§Ć£o entre a giardĆase e doenƧas alĆ©rgicas das vias aĆ©reas. Diante disso, o presente estudo se propĆ“s a verificar a relaĆ§Ć£o entre a infecĆ§Ć£o por G. lamblia em crianƧas de Ć”rea urbana e reatividade alĆ©rgica respiratĆ³ria. MĆTODOS: O estudo incluiu 110 pacientes, de ambos os sexos e idades, entre 5 e 15 anos. Os pacientes foram submetidos a questionĆ”rios de avaliaĆ§Ć£o dos sintomas clĆnicos, testes cutĆ¢neos de leitura imediata e exames coproparasitolĆ³gicos e sorolĆ³gicos. RESULTADOS: Foi verificada uma frequĆŖncia elevada de crianƧas infectadas por G. lamblia (45%, 50/110). A infecĆ§Ć£o pelo protozoĆ”rio nĆ£o foi associada com maior risco de alergias respiratĆ³rias (p = 0,075), elevaĆ§Ć£o de IgE total (p = 0,701), IgE especĆfica (p = 0,250) ou teste cutĆ¢neo positivo para diferentes alĆ©rgenos ambientais (p = 0,239). CONCLUSĆO: O estudo demonstrou que a presenƧa dos sintomas de asma, atopia cutĆ¢nea e marcadores sorolĆ³gicos nĆ£o foram associados com a presenƧa de infecĆ§Ć£o pela G. lamblia nessa amostra de crianƧas.MinistĆ©rio da SaĆŗde (Governo Federal do Brasil)MinistĆ©rio da CiĆŖncia e e Tecnologia (Governo Federal do Brasil)Conselho Nacional de Desenvolvimento CientĆfico e TecnolĆ³gico (CNPq)Universidade Federal de Pernambuco LaboratĆ³rio de Imunopatologia Keizo AsamiUFPE LaboratĆ³rio de Imunopatologia Keizo AsamiUFPE Hospital das CĆnicas ImunologiaUFPE Hospital das ClĆnicas ImunologiaUFPE Hospital das ClĆnicasUniversidade Federal de SĆ£o Paulo (UNIFESP) Pediatria e CiĆŖncias AplicadasUNIFESP Imunologia ClĆnica e Reumatologia Pediatria e CiĆŖncias Aplicadas PediatriaUFPEUFPE Programa de PĆ³s-graduaĆ§Ć£o em CiĆŖncias da SaĆŗdeUNIFESP, Pediatria e CiĆŖncias AplicadasUNIFESP, Imunologia ClĆnica e Reumatologia Pediatria e CiĆŖncias Aplicadas PediatriaCNPq: 402666/2005-4SciEL
Classification performance for covid patient prognosis from automatic ai segmentationāa single-center study
Background: COVID assessment can be performed using the recently developed individual risk score (prediction of severe respiratory failure in hospitalized patients with SARS-COV2 infection, PREDI-CO score) based on High Resolution Computed Tomography. In this study, we evaluated the possibility of automatizing this estimation using semi-supervised AI-based Radiomics, leveraging the possibility of performing non-supervised segmentation of ground-glass areas. Methods: We collected 92 from patients treated in the IRCCS SantāOrsola-Malpighi Policlinic and public databases; each lung was segmented using a pre-trained AI method; ground-glass opacity was identified using a novel, non-supervised approach; radiomic measurements were collected and used to predict clinically relevant scores, with particular focus on mortality and the PREDI-CO score. We compared the prediction obtained through different machine learning approaches. Results: All the methods obtained a well-balanced accuracy (70%) on the PREDI-CO score but did not obtain satisfying results on other clinical characteristics due to unbalance between the classes. Conclusions: Semi-supervised segmentation, implemented using a combination of non-supervised segmentation and feature extraction, seems to be a viable approach for patient stratification and could be leveraged to train more complex models. This would be useful in a high-demand situation similar to the current pandemic to support gold-standard segmentation for AI training
āO sibling, where art thou?ā ā a review of avian sibling recognition with respect to the mammalian literature
Avian literature on sibling recognition is rare compared to that developed by mammalian researchers. We compare avian and mammalian research on sibling recognition to identify why avian work is rare, how approaches differ and what avian and mammalian researchers can learn from each other. Three factors: (1) biological differences between birds and mammals, (2) conceptual biases and (3) practical constraints, appear to influence our current understanding. Avian research focuses on colonial species because sibling recognition is considered adaptive where āmixing potentialā of dependent young is high; research on a wider range of species, breeding systems and ecological conditions is now needed. Studies of acoustic recognition cues dominate avian literature; other types of cues (e.g. visual, olfactory) deserve further attention. The effect of gender on avian sibling recognition has yet to be investigated; mammalian work shows that gender can have important influences. Most importantly, many researchers assume that birds recognise siblings through ādirect familiarisationā (commonly known as associative learning or familiarity); future experiments should also incorporate tests for āindirect familiarisationā (commonly known as phenotype matching). If direct familiarisation proves crucial, avian research should investigate how periods of separation influence sibling discrimination. Mammalian researchers typically interpret sibling recognition in broad functional terms (nepotism, optimal outbreeding); some avian researchers more successfully identify specific and testable adaptive explanations, with greater relevance to natural contexts. We end by reporting exciting discoveries from recent studies of avian sibling recognition that inspire further interest in this topic
The Quantum Sine-Gordon model in perturbative AQFT
We study the Sine-Gordon model with Minkowski signature in the framework of perturbative algebraic quantum field theory. We calculate the vertex operator algebra braiding property. We prove that in the finite regime of the model, the expectation valueāwith respect to the vacuum or a Hadamard stateāof the Epstein Glaser S-matrix and the interacting current or the field respectively converge, both given as formal power series
Combined effects of time spent in physical activity, sedentary behaviors and sleep on obesity and cardio-metabolic health markers: a novel compositional data analysis approach
<div><p>The associations between time spent in sleep, sedentary behaviors (SB) and physical activity with health are usually studied without taking into account that time is finite during the day, so time spent in each of these behaviors are codependent. Therefore, little is known about the combined effect of time spent in sleep, SB and physical activity, that together constitute a composite whole, on obesity and cardio-metabolic health markers. Cross-sectional analysis of NHANES 2005ā6 cycle on N = 1937 adults, was undertaken using a compositional analysis paradigm, which accounts for this intrinsic codependence. Time spent in SB, light intensity (LIPA) and moderate to vigorous activity (MVPA) was determined from accelerometry and combined with self-reported sleep time to obtain the 24 hour time budget composition. The distribution of time spent in sleep, SB, LIPA and MVPA is significantly associated with BMI, waist circumference, triglycerides, plasma glucose, plasma insulin (all p<0.001), and systolic (p<0.001) and diastolic blood pressure (p<0.003), but not HDL or LDL. Within the composition, the strongest positive effect is found for the proportion of time spent in MVPA. Strikingly, the effects of MVPA replacing another behavior and of MVPA being displaced by another behavior are asymmetric. For example, re-allocating 10 minutes of SB to MVPA was associated with a lower waist circumference by 0.001% but if 10 minutes of MVPA is displaced by SB this was associated with a 0.84% higher waist circumference. The proportion of time spent in LIPA and SB were detrimentally associated with obesity and cardiovascular disease markers, but the association with SB was stronger. For diabetes risk markers, replacing SB with LIPA was associated with more favorable outcomes. Time spent in MVPA is an important target for intervention and preventing transfer of time from LIPA to SB might lessen the negative effects of physical inactivity.</p></div
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