922 research outputs found
The effect of curvature and topology on membrane hydrodynamics
We study the mobility of extended objects (rods) on a spherical liquid-liquid
interface to show how this quantity is modified in a striking manner by both
the curvature and the topology of the interface. We present theoretical
calculations and experimental measurements of the interfacial fluid velocity
field around a moving rod bound to the crowded interface of a water-in-oil
droplet. By using different droplet sizes, membrane viscosities, and rod
lengths, we show that the viscosity mismatch between the interior and exterior
fluids leads to a suppression of the fluid flow on small droplets that cannot
be captured by the flat interface predictions.Comment: 4 pages, 3 figure
Polyelectrolyte Bundles
Using extensive Molecular Dynamics simulations we study the behavior of
polyelectrolytes with hydrophobic side chains, which are known to form
cylindrical micelles in aqueous solution. We investigate the stability of such
bundles with respect to hydrophobicity, the strength of the electrostatic
interaction, and the bundle size. We show that for the parameter range relevant
for sulfonated poly-para-phenylenes (PPP) one finds a stable finite bundle
size. In a more generic model we also show the influence of the length of the
precursor oligomer on the stability of the bundles. We also point out that our
model has close similarities to DNA solutions with added condensing agents,
hinting to the possibility that the size of DNA aggregates is under certain
circumstances thermodynamically limited.Comment: 10 pages, 8 figure
Hydrodynamic coupling between two fluid membranes
The coupled in-plane diffusion dynamics between point-particles embedded in
stacked fluid membranes are investigated. We calculate the contributions to the
coupling longitudinal and transverse diffusion coefficients due to particle
motion within the different as well as the same membranes. The stacked geometry
leads to a hydrodynamic coupling between the two membranes.Comment: 9 Pages, 5 figures. Accepted for publication in J. Phys.: Condens.
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Effective Viscosity of a Dilute Suspension of Membrane-bound Inclusions
When particulate suspensions are sheared, perturbations in the shear flows
around the rigid particles increase the local energy dissipation, so that the
viscosity of the suspension is effectively higher than that of the solvent. For
bulk (three-dimensional) fluids, understanding this viscosity enhancement is a
classic problem in hydrodynamics that originated over a century ago with
Einstein's study of a dilute suspension of spherical particles.
\cite{Einstein1} In this paper, we investigate the analogous problem of the
effective viscosity of a suspension of disks embedded in a two-dimensional
membrane or interface. Unlike the hydrodynamics of bulk fluids, low-Reynolds
number membrane hydrodynamics is characterized by an inherent length scale
generated by the coupling of the membrane to the bulk fluids that surround it.
As a result, we find that the size of the particles in the suspension relative
to this hydrodynamic length scale has a dramatic effect on the effective
viscosity of the suspension. Our study also helps to elucidate the mathematical
tools needed to solve the mixed boundary value problems that generically arise
when considering the motion of rigid inclusions in fluid membranes.Comment: 33 pages, 4 figures (preprint); submitted to Physics of Fluid
Cytokine and immunoglobulin production by PWM-stimulated peripheral and tumor-infiltrating lymphocytes of undifferentiated nasopharyngeal carcinoma (NPC) patients
BACKGROUND: Undifferentiated Nasopharyngeal Carcinoma (NPC) patients show a characteristic pattern of antibody responses to the Epstein-Barr virus (EBV) which is regularly associated with this tumor. However, no EBV-specific cytotoxic activity is detectable by the standard chromium-release assay at both peripheral and intratumoral levels. The mechanisms underlying this discrepancy between the humoral and cellular immune responses in NPC are still unknown, but might be related to an imbalance in immunoregulatory interleukin production. In this report, we investigated the ability of peripheral (PBL) and tumor- infiltrating (TIL) lymphocytes of undifferentiated NPC patients to produce in vitro three interleukins (IL-2, IL-6, IL-10) and three immunoglobulin isotypes (IgM, IgG, IgA). METHODS: Lymphocytes from 17 patients and 17 controls were cultured in the presence of Pokeweed mitogen (PWM) for 12 days and their culture supernatants were tested for interleukins and immunoglobulins by specific enzyme-linked immunosorbent assays (ELISA). Data were analysed using Student's t-test and probability values below 5% were considered significant. RESULTS: The data obtained indicated that TIL of NPC patients produced significantly more IL-2 (p = 0,0002), IL-10 (p = 0,020), IgM (p= 0,0003) and IgG (p < 0,0001) than their PBL. On the other hand, patients PBL produced significantly higher levels of IL-2 (p = 0,022), IL-10 (p = 0,016) and IgM (p = 0,004) than those of controls. No significant differences for IL-6 and IgA were observed. CONCLUSION: Taken together, our data reinforce the possibility of an imbalance in immunoregulatory interleukin production in NPC patients. An increased ability to produce cytokines such as IL-10 may underlie the discrepancy between humoral and cellular immune responses characteristic of NPC
Distant but similar: Simultaneous drop in the abundance of three independent amphibian communities
Amphibian species are declining worldwide, with a negative trend affecting both rare and widespread species. There is increasing evidence that resources must be allocated not only toward the monitoring of rare and charismatic species; however, the attention toward abundant species has often been minimal. Here, we describe the strong reduction in the numbers of several widespread amphibian species over the last 3 years observed in three independent amphibian monitoring studies conducted in an alpine, floodplain, and urban landscape in Italy, Germany, and Russia, respectively. The decline was particularly strong in juveniles, but adults and egg clutches were also affected. Such declining rates, if prolonged in the future years, will likely pose a serious threat to the populations' ability to recover and might increase extinction risk also in abundant and widespread species. © 2022 The Authors. Conservation Science and Practice published by Wiley Periodicals LLC on behalf of Society for Conservation Biology.European Herpetological SocietyInstitute of Plant and Animal EcologyItalian Ministry of Environment, (PNM‐EU‐2018‐0009926)Paneveggio-Pale di San Martino Nature ParkPaneveggio‐Pale di San Martino Nature ParkSEH, (DP‐615, RA‐485/19)Ural Branch, Russian Academy of Sciences, UB RASFunding text 1: The study in Italy was authorized by the Italian Ministry of Environment (authorization PNM-EU-2018-0009926) and supported by Paneveggio-Pale di San Martino Nature Park. Part of funding was provided by the European Herpetological Society (SEH). The study in Germany has been authorized through a nature conservation exemption from the prohibitions of § 44 para. 1 no. 1, 2 BNatSchG (Federal Nature Conservation Act) and § 4 para. 1 no. 1 BArtSchV (Federal Species Protection Ordinance) by the respective responsible lower nature conservation authorities that allowed catching and handling native amphibian species. Parts of the research in Germany have been paid through the Helmholtz International Fellow Award, grant number DP-615, RA-485/19. The study in Russia was performed within the framework of the state contract number 122021000082-0 with the Institute of Plant and Animal Ecology, Ural Branch of the Russian Academy of Sciences.Funding text 2: The study in Italy was authorized by the Italian Ministry of Environment (authorization PNM‐EU‐2018‐0009926) and supported by Paneveggio‐Pale di San Martino Nature Park. Part of funding was provided by the European Herpetological Society (SEH). The study in Germany has been authorized through a nature conservation exemption from the prohibitions of § 44 para. 1 no. 1, 2 BNatSchG (Federal Nature Conservation Act) and § 4 para. 1 no. 1 BArtSchV (Federal Species Protection Ordinance) by the respective responsible lower nature conservation authorities that allowed catching and handling native amphibian species. Parts of the research in Germany have been paid through the Helmholtz International Fellow Award, grant number DP‐615, RA‐485/19. The study in Russia was performed within the framework of the state contract number 122021000082‐0 with the Institute of Plant and Animal Ecology, Ural Branch of the Russian Academy of Sciences
Effects of exogenous dietary advanced glycation end products on the cross-talk mechanisms linking microbiota to metabolic inflammation
Heat-processed diets contain high amounts of advanced glycation end products (AGEs). Here we explore the impact of an AGE-enriched diet on markers of metabolic and inflammatory disorders as well as on gut microbiota composition and plasma proteins glycosylation pattern. C57BL/6 mice were allocated into control diet (CD, n = 15) and AGE-enriched diet (AGE-D, n = 15) for 22 weeks. AGE-D was prepared replacing casein by methylglyoxal hydroimidazolone-modified casein. AGE-D evoked increased insulin and a significant reduction of GIP/GLP-1 incretins and ghrelin plasma levels, altered glucose tolerance, and impaired insulin signaling transduction in the skeletal muscle. Moreover, AGE-D modified the systemic glycosylation profile, as analyzed by lectin microarray, and increased N\u3b5-carboxymethyllysine immunoreactivity and AGEs receptor levels in ileum and submandibular glands. These effects were associated to increased systemic levels of cytokines and impaired gut microbial composition and homeostasis. Significant correlations were recorded between changes in bacterial population and in incretins and inflammatory markers levels. Overall, our data indicates that chronic exposure to dietary AGEs lead to a significant unbalance in incretins axis, markers of metabolic inflammation, and a reshape of both the intestinal microbiota and plasma protein glycosylation profile, suggesting intriguing pathological mechanisms underlying AGEs-induced metabolic derangements
Conceptual Framework on Workplace Deviance Behavior: A Review
This article aims to highlight the importance of organizational climate with both destructive and constructive deviance behaviour in different cultural setting with workplace as a common ground. First, we discuss the need for research in workplace deviance especially destructive and constructive deviance behaviour with the review of previous studies from deviance literature. Next, we present the importance of climate and culture with both destructive and constructive deviance by proposing relationship among them with the help of a framework. The presented theoretical framework can be useful for conducting future empirical research. Finally, we present the conclusion and future research in conducting cross-national research with respect to deviance
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