Heterogeneous aggregation in binary colloidal alloys

Molecular dynamics (MD) simulation has been employed to study the nonequilibrium structure formation of two types of particles in a colloidal suspension, driven by type-dependent forces. We examined the time evolution of structure formation as well as the structural properties of the resulting aggregation by studying the radial distribution function (RDF). The resulting aggregation is well described by a binary colloidal gelation. We compared the structural properties to those for one type of particles. From the MD results, it is evident that there are significant differences between the RDF's of the two cases. Moreover, we found that the average coordination number is generally larger in the monodisperse case for all area fractions considered. Thus, by means of heterogeneous aggregation, it is possible to obtain a wide variety of structures while more close-packed structures are formed for monodisperse colloidal aggregation.Comment: 15 pages, 5 eps figures; preliminary results have been reported at the APS March Meeting 2002; accepted by Physica

Hemiplegia in Men: A Case Study

Hemiplegia, or paralysis of one side of the body, is caused by injury or illness (for example, a stroke), and leads to other disabilities. People with hemiplegia are limited physically in their daily activities. This limitation affects their social well-being and thus can lead to depression. This paper provides a comprehensive literature review on hemiplegia in men. A single case study of a man with hemiplegia living in Hong Kong is also presented here. A critical discussion of the signs and symptoms of “male-type” depression and humanising attitudes towards men with hemiplegia follows. Critical areas in rehabilitation, social support, and developing partnerships are also highlighted. This paper intends to facilitate better understanding by health and social care providers of the needs of men with hemiplegia. Implications for clinical practice and research are likewise addressed. Further studies using multiple case studies are recommended to ensure a comprehensive understanding of hemiplegia in men

Spatial constraints underlying the retinal mosaics of two types of horizontal cells in cat and macaque

Most types of retinal neurons are spatially positioned in non-random patterns, termed retinal mosaics. Several developmental mechanisms are thought to be important in the formation of these mosaics. Most evidence to date suggests that homotypic constraints within a type of neuron are dominant, and that heterotypic interactions between different types of neuron are rare. In an analysis of macaque H1 and H2 horizontal cell mosaics, W\"assle et al. (2000) suggested that the high regularity index of the combined H1 and H2 mosaic might be caused by heterotypic interactions during development. Here we use computer modelling to suggest that the high regularity index of the combined H1 and H2 mosaic is a by-product of the basic constraint that two neurons cannot occupy the same space. The spatial arrangement of type A and type B horizontal cells in cat retina also follow this same principle

Cell–cell Interaction Underlies Formation of Fluid in the Male Reproductive Tract of the Rat

The epithelia lining the epididymides of many species consists of several cell types. We have provided evidence that the basal cells are essential to the integrated functions of the epithelium. Basal cells, but not principal cells, and other cells in the epididymis express TRPC3 and COX-1. We have isolated basal cells from intact rat epididymis using antibody-coated Dynabeads and subjected them to whole-cell patch-clamp measurement of nonselective cation channel activity, a feature of TRPC3 protein, and Fluo-3 fluorescence measurement of intracellular Ca2+ concentration. The results show that a nonselective cation current blockable by La3+ (0.1 mM), Gd3+ (0.1 mM), or SKF96365 (20 μM) could be activated by lysylbradykinin (200 nM). In cells loaded with Fluo-3, addition of lysylbradykinin (100 nM) caused a sustained increase of intracellular Ca2+. This effect was blocked by Gd3+ (0.1 mM) or SKF96365 (20 μM) and was not observed in Fluo-3–loaded principal cells. Stimulation of basal cell/principal cell cocultures with lysylbradykinin (200 nM) evoked in principal cells a current with CFTR-Cl− channel characteristics. Isolated principal cells in the absence of basal cells did not respond to lysylbradykinin but responded to PGE2 (100 nM) with activation of a CFTR-like current. Basal cells, but not principal cells, released prostaglandin E2 when stimulated with lysylbradykinin (100 nM). The release was blocked by SKF96365 (20 μM) and BAPTA-AM (0.05 or 0.1 mM). Confluent cell monolayers harvested from a mixture of disaggregated principal cells and basal cells responded to lysylbradykinin (100 nM) and PGE2 (500 nM) with an increase in electrogenic anion secretion. The former response was dependent on prostaglandin synthesis as piroxicam blocked the response. However, cell cultures obtained from principal cells alone responded to PGE2 but not to bradykinin. These results support the notion that basal cells regulate principal cells through a Ca2+ and COX signaling pathway

The cardiorespiratory fitness, level of physical activity and cardiovascular risk factors among university security guards

This cross-sectional study explores the correlation of cardiorespiratory fitness,physical status and cardiovascular risk factors among security guards in a public university in Sarawak, Malaysia. A questionnaire was used to collect socio-demographic information, and the International Physical Activity Questionnaire — Short-form (IPAQ-SF) was used to collect information on physical activity level. Physical fitness of respondents was determined using the YMCA three minutes physical fitness test and blood test to check fasting sugar and cholesterol levels. Data was analysed using SPSS version 19. A total of 98 respondents participated in the study of which the majority were male (89.8%). The respondents were found to have a mean VO2max of 24.46 ± 3.58 mL/kg/min as an assessment of their cardiorespiratory fitness. Fifty-three per cent of respondents were self-reported smokers, while 34.7% had high blood pressure, 37.8% had abnormal cholesterol level, 37.8% had abnormal blood glucose and 34.7% had an abnormal body mass index (BMI). More than 90% of the respondents self-reported a moderate to high level of physical activity. Analysis of multiple linear regression shows physical activity level (PAL) (adj b 2.653, 95% CI 1.371, 3.936, p < 0.01) and waist circumference (adj b -1.447, 95% CI -0.146, -2.748, p = 0.03) to have significant association with cardiorespiratory fitness. Findings indicate that the majority of participating security guards have poor cardiorespiratory fitness and are at high risk of developing hypertension, hyperglycemia and hypercholesterolemia. It is recommended that a healthier working environment with compulsory regular exercise and medical check-ups should be put into practice to minimise risk to their job satisfaction and performance

Reduced insulin signaling maintains electrical transmission in a neural circuit in aging flies

Lowered insulin/insulin-like growth factor (IGF) signaling (IIS) can extend healthy lifespan in worms, flies, and mice, but it can also have adverse effects (the “insulin paradox”). Chronic, moderately lowered IIS rescues age-related decline in neurotransmission through the Drosophila giant fiber system (GFS), a simple escape response neuronal circuit, by increasing targeting of the gap junctional protein innexin shaking-B to gap junctions (GJs). Endosomal recycling of GJs was also stimulated in cultured human cells when IIS was reduced. Furthermore, increasing the activity of the recycling small guanosine triphosphatases (GTPases) Rab4 or Rab11 was sufficient to maintain GJs upon elevated IIS in cultured human cells and in flies, and to rescue age-related loss of GJs and of GFS function. Lowered IIS thus elevates endosomal recycling of GJs in neurons and other cell types, pointing to a cellular mechanism for therapeutic intervention into aging-related neuronal disorders

Out-of-equilibrium electromagnetic radiation

We derive general formulas for photon and dilepton production rates from an arbitrary non-equilibrated medium from first principles in quantum field theory. At lowest order in the electromagnetic coupling constant, these relate the rates to the unequal-time in-medium photon polarization tensor and generalize the corresponding expressions for a system in thermodynamic equilibrium. We formulate the question of electromagnetic radiation in real time as an initial value problem and consistently describe the virtual electromagnetic dressing of the initial state. In the limit of slowly evolving systems, we recover known expressions for the emission rates and work out the first correction to the static formulas in a systematic gradient expansion. Finally, we discuss the possible application of recently developed techniques in non-equilibrium quantum field theory to the problem of electromagnetic radiation. We argue, in particular, that the two-particle-irreducible (2PI) effective action formalism provides a powerful resummation scheme for the description of multiple scattering effects, such as the Landau-Pomeranchuk-Migdal suppression recently discussed in the context of equilibrium QCD.Comment: 34 pages, 9 figures, uses JHEP3.cl

Glassy Phase Transition and Stability in Black Holes

Black hole thermodynamics, confined to the semi-classical regime, cannot address the thermodynamic stability of a black hole in flat space. Here we show that inclusion of correction beyond the semi-classical approximation makes a black hole thermodynamically stable. This stability is reached through a phase transition. By using Ehrenfest's scheme we further prove that this is a glassy phase transition with a Prigogine-Defay ratio close to 3. This value is well placed within the desired bound (2 to 5) for a glassy phase transition. Thus our analysis indicates a very close connection between the phase transition phenomena of a black hole and glass forming systems. Finally, we discuss the robustness of our results by considering different normalisations for the correction term.Comment: v3, minor changes over v2, references added, LaTeX-2e, 18 pages, 3 ps figures, to appear in Eour. Phys. Jour.

Sarcocystis nesbitti causes acute, relapsing febrile myositis with a high attack rate: Description of a large outbreak of muscular sarcocystosis in Pangkor Island, Malaysia, 2012

Background: From the 17th to 19th January 2012, a group of 92 college students and teachers attended a retreat in a hotel located on Pangkor Island, off the west coast of Peninsular Malaysia. Following the onset of symptoms in many participants who presented to our institute, an investigation was undertaken which ultimately identified Sarcocystis nesbitti as the cause of this outbreak. Methodology/Principal Findings: All retreat participants were identified, and clinical and epidemiological information was obtained via clinical review and self-reported answers to a structured questionnaire. Laboratory, imaging and muscle biopsy results were evaluated and possible sources of exposure, in particular water supply, were investigated. At an average of 9-11 days upon return from the retreat, 89 (97) of the participants became ill. A vast majority of 94 had fever with 57 of these persons experiencing relapsing fever. Myalgia was present in 91 of patients. Facial swelling from myositis of jaw muscles occurred in 9 (10) patients. The median duration of symptoms was 17 days (IQR 7 to 30 days; range 3 to 112). Out of 4 muscle biopsies, sarcocysts were identified in 3. S. nesbitti was identified by PCR in 3 of the 4 biopsies including one biopsy without observed sarcocyst. Non-Malaysians had a median duration of symptoms longer than that of Malaysians (27.5 days vs. 14 days, p = 0.001) and were more likely to experience moderate or severe myalgia compared to mild myalgia (83.3 vs. 40.0, p = 0.002). Conclusions/Significance: The similarity of the symptoms and clustered time of onset suggests that all affected persons had muscular sarcocystosis. This is the largest human outbreak of sarcocystosis ever reported, with the specific Sarcocystis species identified. The largely non-specific clinical features of this illness suggest that S. nesbitti may be an under diagnosed infection in the tropics