3,440 research outputs found
Charge diffusion and the butterfly effect in striped holographic matter
Recently, it has been proposed that the butterfly velocity - a speed at which
quantum information propagates - may provide a fundamental bound on diffusion
constants in dirty incoherent metals. We analytically compute the charge
diffusion constant and the butterfly velocity in charge-neutral holographic
matter with long wavelength "hydrodynamic" disorder in a single spatial
direction. In this limit, we find that the butterfly velocity does not set a
sharp lower bound for the charge diffusion constant.Comment: 16+7 pages; 1 figure. v2: published versio
Uniqueness of and pure supergravities in 4D
After proving the impossibility of consistent non-minimal coupling of a real
Rarita-Schwinger gauge field to electromagnetism, we re-derive the necessity of
introducing the graviton in order to couple a complex Rarita-Schwinger gauge
field to electromagnetism, with or without a cosmological term, thereby
obtaining pure supergravity as the only possibility. These results
are obtained with the BRST-BV deformation method around the flat and (A)dS
backgrounds in 4 dimensions. The same method applied to vectors, real spin-3/2 gauge fields and at most one real spinor field also requires
gravity and yields pure supergravity as well as pure
supergravity coupled to a vector supermultiplet, with or without cosmological
terms. Independently from the matter content, we finally derive strong
necessary quadratic constraints on the possible gaugings for an arbitrary
number of spin-1 and spin-3/2 gauge fields, that are relevant for larger
supergravities.Comment: LaTeX, 31 + 1 pages, no figure. v2: Extended discussion at the end of
Section 3, corrected typos and references adde
Identifying and Implementing Assessments of Upper Extremity Motor Control for Patients with Stroke or Parkinson’s Disease
The authors collaborated with a team of clinicians at a skilled nursing facility (SNF) in Gig Harbor, WA to identify the need for measures of UE functional use that are most appropriate to utilize with the two largest client populations at their facility, stroke and Parkinson’s disease (PD). In order to meet the clinical utility characteristics identified as important by the clinicians, the authors searched two databases that contain overviews of assessments. This search identified five stroke assessments and two PD assessments that met the clinical utility parameters outlined by the clinicians. The authors then conducted a systematic literature search to identify any relevant studies pertaining to each assessment. These studies were reviewed and the results presented in the form of a critical appraisal of the topic (CAT) that included the purpose, measure, population, psychometric characteristics, results and limitations of the studies. The initial search for articles yielded 869 articles, 33 of which met the inclusion criteria. The authors recommend use of the Chedoke Arm and Hand Activity Inventory-9 assessment with clients post-stroke due to its robust evidence and wide variety of levels of impairments post-stroke included in the studies, and use of the Muscle Disorder Society’s Unified Parkinson’s Disease Rating Scale assessment with clients with PD due to its inclusion of functional tasks and higher volume of research.
The knowledge translation implementation phase of the project involved an in-service (interactive demonstration and scoring) and two brochures outlining the findings related to each assessment. A follow-up survey measured the effectiveness of the in-service and the value of the research to clinicians’ occupational therapy practice at their clinic. The survey results indicated that the clinicians found the research helpful and the knowledge translation process efficient. In addition, they indicated that it is likely that they will implement the CAHAI and the MDS-UPDRS assessments at their facility
Several submaximal exercise tests reliable, valid and acceptable in patients with chronic pain, fibromyalgia or chronic fatigue: a systematic review.
Question: Are submaximal and maximal exercise tests reliable, valid and acceptable in people with chronic pain, fibromyalgia and fatigue disorders? Design: Systematic review of studies of the psychometric properties of exercise tests. Participants: People older than 18 years with chronic pain, fibromyalgia and chronic fatigue disorders. Intervention: Studies of the measurement properties of tests of physical capacity in people with chronic pain, fibromyalgia or chronic fatigue disorders were included. Outcome measures: Studies were required to report: reliability coefficients (intraclass correlation coefficient, alpha reliability coefficient, limits of agreements and Bland-Altman plots); validity coefficients (intraclass correlation coefficient, Spearman's correlation, Kendal T coefficient, Pearson's correlation); or dropout rates. Results: Fourteen studies were eligible: none had low risk of bias, 10 had unclear risk of bias and four had high risk of bias. The included studies evaluated: Åstrand test; modified Åstrand test; Lean body mass-based Åstrand test; submaximal bicycle ergometer test following another protocol other than Åstrand test; 2-km walk test; 5-minute, 6-minute and 10-minute walk tests; shuttle walk test; and modified symptom-limited Bruce treadmill test. None of the studies assessed maximal exercise tests. Where they had been tested, reliability and validity were generally high. Dropout rates were generally acceptable. The 2-km walk test was not recommended in fibromyalgia. Conclusion: Moderate evidence was found for reliability, validity and acceptability of submaximal exercise tests in patients with chronic pain, fibromyalgia or chronic fatigue. There is no evidence about maximal exercise tests in patients with chronic pain, fibromyalgia and chronic fatigue
Update on the fluorometric measurement of enzymatic activities for Lysosomal Storage Disorder detection: The example of MPS VI
Lysosomal Storage Disorders (LSD) are rare diseases that as a whole havea combined incidence ranging from 1:1500 to 1:7000 live births. One of suchdiseases is Mucopolysaccharidosis VI (MPS VI), or Maroteaux Lamy Syndrome.MPS VI patients undergo devastating and irreversible skeletal alterations andmultisystemic failure as from early childhood due to reduced Arylsulfatse B(ARSB) enzyme activity.Reaching a final diagnosis is not always a short cut path, but rather a yearslongbattle against uncertainty and unnecessary medical interventions. Ouraim is to contribute from the bench table with different approaches that couldserve as alternatives to pre-existing assays for screening and diagnosing MPSVI and other LSD.The present work is based on our research article authored by Franco etal.1 where we studied the effect of blood-derived hemoglobin, and other bloodcomponents, on the fluorescence of 4-Methylumbelliferone when measuringARSB enzyme activity from dried blood spot (DBS) samples.Our experience indicates that to date there are plenty of differentapproaches for measuring ARSB enzyme activity, although the sample typerequired or the assay in itself often make them more adaptable for either highthroughput screening or small scale diagnostics.As a whole, the fluorometric determinations seem to be the mostaccessible to low budget laboratories with equally valuable performancesas a sophisticated mass spectrometry analysis for this disease. Furthermore,the DBS serves as an attractive sample type for screening the disease in largepopulations.Fil: Franco, Paula Gabriela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas ; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquimica. Departamento de Quimica Biologica. Cátedra de Química Biológica Patológica; ArgentinaFil: Adamo, Ana María. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas ; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquimica. Departamento de Quimica Biologica. Cátedra de Química Biológica Patológica; ArgentinaFil: Mathieu, Patricia Andrea. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas ; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquimica. Departamento de Quimica Biologica. Cátedra de Química Biológica Patológica; ArgentinaFil: Perez, Maria Julia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas ; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquimica. Departamento de Quimica Biologica. Cátedra de Química Biológica Patológica; ArgentinaFil: Setton, Clara Patricia. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas ; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquimica. Departamento de Quimica Biologica. Cátedra de Química Biológica Patológica; ArgentinaFil: Silvestroff, Lucas. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Química y Físico-Química Biológicas ; Argentina. Universidad de Buenos Aires. Facultad de Farmacia y Bioquimica. Departamento de Quimica Biologica. Cátedra de Química Biológica Patológica; Argentin
Strong, lightweight, and recoverable three-dimensional ceramic nanolattices
Ceramics have some of the highest strength- and stiffness-to-weight ratios of any material but are suboptimal for use as structural materials because of their brittleness and sensitivity to flaws. We demonstrate the creation of structural metamaterials composed of nanoscale ceramics that are simultaneously ultralight, strong, and energy-absorbing and can recover their original shape after compressions in excess of 50% strain. Hollow-tube alumina nanolattices were fabricated using two-photon lithography, atomic layer deposition, and oxygen plasma etching. Structures were made with wall thicknesses of 5 to 60 nanometers and densities of 6.3 to 258 kilograms per cubic meter. Compression experiments revealed that optimizing the wall thickness-to-radius ratio of the tubes can suppress brittle fracture in the constituent solid in favor of elastic shell buckling, resulting in ductile-like deformation and recoverability
Species of Contracaecum Parasitizing the Magellanic Penguin Spheniscus magellanicus (Spheniscidae) from the Argentinean Coast
Anisakid nematodes have a worldwide distribution and are associated with fishes, birds, and marine mammals from freshwater, brackish, and marine systems. The aims of this work are to report for the first time Contracaecum mirounga parasitizing the Magellanic penguin Spheniscus magellanicus, to report another Contracaecum species in the same host species, and to discuss the validity of Contracaeceum spheniscus. Several dead chicks, juveniles, and adults of S. magellanicus were collected along the Argentinean coast from 2002 to 2009. Nematodes were removed from digestive tracts and studied using both light and scanning electron microscopy. Nematode prevalences were 2.38% for C. mirounga and 12.5% for Contracaecum sp. Contracaecum mirounga was found in 1 penguin from Península Valdés, Chubut. This species is known as a specific parasite of marine mammals such as Pinnipedia, thereby suggesting that this nematode is not as specific as believed. Another species of Contracaecum sp. was found parasitizing 1 penguin from the Río de la Plata coast. It possessed an unusual interlabial morphology and arrangement of male caudal papillae. Despite the low prevalence, the distinct morphological features are convincing and support the presence of a new Contracaecum species. However, a formal description is not presented because sufficient male specimens are lacking. Finally, C. spheniscus is considered a junior synonym of Contracaecum pelagicum. Future molecular studies might be helpful to determine the real diversity of Contracaecum species parasitizing S. magellanicus considering the number of sibling species recognized among the anisakids.Fil: Garbin, Lucas. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. División Zoología de Vertebrados. Sección Ornitología; ArgentinaFil: Diaz, Julia Inés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; ArgentinaFil: Navone, Graciela Teresa. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Centro de Estudios Parasitológicos y de Vectores. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo. Centro de Estudios Parasitológicos y de Vectores; Argentin
Direct simulation of secondary flow turbulence in curved pipelines
En este trabajo se estudia el flujo secundario en ductos curvos. El flujo secundario puede ser originado por la curvatura del ducto (primer tipo) o por la presencia de la turbulencia (segundo tipo). Se analizan aquí los patrones de circulación secundaria y la influencia de ésta en el flujo medio para dos valores de radio medio de curvatura. Se observa que los patrones de corriente se ven fuertemente afectados por el flujo secundario de primer tipo que genera un desplazamiento del valor máximo hacia el radio externo mientras que el flujo secundario del segundo tipo actúa modificando los contornos de velocidad en las regiones cercanas a las paredes horizontales del ducto. Estas modificaciones impactan en los esfuerzos de corte en las paredes y, en consecuencia, en los procesos de erosión y deposición del sedimentos y en la modificación de la resistencia hidráulica del ducto. El patrón de las celdas de recirculación del flujo secundario varía en los casos estudiados lo que evidencia la existencia de distintos mecanismos de mezclado de la corriente. Para este estudio se desarrollan simulaciones directas de turbulencia (DNS, por sus siglas en inglés) empleando un código pseudoespectral.Secondary flow can be originated by duct curvature (first kind) or by the presence of turbulence (second kind). This work focuses on the study of secondary flow in a curve duct of square section in turbulent regime by means of fully resolved direct numeric simulations. Secondary flow patterns and its influence on mean flow are analyzed for two values of duct curvature. It is observed that flow patterns are strongly influenced by secondary flow generating a displacement of the maximum value towards the external radius, which modifies velocity contours in regions near the horizontal walls of the duct. Consequently, wall shear stresses and flow recirculation cells change substantially. These findings may have an important impact on sediment erosion and deposition, and on mixing mechanisms.Fil: Martorana, Julia Victoria. Universidad Nacional de Río Negro; Argentina. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; ArgentinaFil: Berardini, Lucas. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; ArgentinaFil: Cantero, Mariano Ignacio. Comisión Nacional de Energía Atómica. Centro Atómico Bariloche; Argentina. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte; Argentin
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