Slow flows of an relativistic perfect fluid in a static gravitational field

Relativistic hydrodynamics of an isentropic fluid in a gravitational field is considered as the particular example from the family of Lagrangian hydrodynamic-type systems which possess an infinite set of integrals of motion due to the symmetry of Lagrangian with respect to relabeling of fluid particle labels. Flows with fixed topology of the vorticity are investigated in quasi-static regime, when deviations of the space-time metric and the density of fluid from the corresponding equilibrium configuration are negligibly small. On the base of the variational principle for frozen-in vortex lines dynamics, the equation of motion for a thin relativistic vortex filament is derived in the local induction approximation.Comment: 4 pages, revtex, no figur

Finite size scaling in the solar wind magnetic field energy density as seen by WIND

Statistical properties of the interplanetary magnetic field fluctuations can provide an important insight into the solar wind turbulent cascade. Recently, analysis of the Probability Density Functions (PDF) of the velocity and magnetic field fluctuations has shown that these exhibit non-Gaussian properties on small time scales while large scale features appear to be uncorrelated. Here we apply the finite size scaling technique to explore the scaling of the magnetic field energy density fluctuations as seen by WIND. We find a single scaling sufficient to collapse the curves over the entire investigated range. The rescaled PDF follow a non Gaussian distribution with asymptotic behavior well described by the Gamma distribution arising from a finite range Lévy walk. Such mono scaling suggests that a Fokker-Planck approach can be applied to study the PDF dynamics. These results strongly suggest the existence of a common, nonlinear process on the time scale up to 26 hours

Case Study of Failure of a R.C.C. Counterfort Retaining Wall

It is a fact that the retaining wall failures have occurred in the distant past as also in recent times and will recur inevitably in future. The reasons of failure are ultimately the errors of judgment to which no humans including the greatest of engineers are immune. Free flow of information on failure incidents is greatly inhibited in most of the cases by the natural tendency to avoid publicizing our mistakes although all human are prone to them. The present study through light on a failure of a recently constructed R.C.C. counter fort Retaining wall. The wall is located near Sangli city in Maharashtra state of India. The wall was constructed in 2003 and there was a heavy rainfall occurred in all over the Maharashtra state continuously in the year 2005 and 2006 subsequently in the catchments of river Krishna. The wall could not sustain the flood impact and there was a sliding, collapse and even rotational failure at some portion of wall was observed. Basically this wall was constructed to protect a village road about 1800m along a stream from flood water. Failure of any structure is usually not attributable to a single cause but in the present case at the prima-facie, it seems that the wall failed due to heavy flood and backwater in the stream from river Krishna and the improper design criteria. The other principle causes of the failure are found out and the remedial measures have been suggested. In this article, an attempt has been made by the authors to make an unbiased technological analysis of the data available, motivated by a desire to find ways of avoiding past mistakes and not sitting on judgment on them

Naturally Occurring Hydroxy Napthoquinones and Their Iron Complexes as Modulators of Radiation Induced Lipid Peroxidation in Synaptosomes

The modulation of radiation induced lipid peroxidation in synaptosomes by iron (II) and iron (III) complexes of two naturally occurring and therapeutically relevant naphthoquinones viz. 5,hydroxy-1,4 naphthoquinone; juglone and 2,hydroxy-1,4 naphthoquinone; lawsone, have been studied. At lower concentrations the complexes enhance lipid peroxidation predominantly through redox cycling as observed for Fe(II)- juglonate while at higher concentrations the complexes tend to limit lipid peroxidation through fast recombinations

A survey of performance enhancement of transmission control protocol (TCP) in wireless ad hoc networks

This Article is provided by the Brunel Open Access Publishing Fund - Copyright @ 2011 Springer OpenTransmission control protocol (TCP), which provides reliable end-to-end data delivery, performs well in traditional wired network environments, while in wireless ad hoc networks, it does not perform well. Compared to wired networks, wireless ad hoc networks have some specific characteristics such as node mobility and a shared medium. Owing to these specific characteristics of wireless ad hoc networks, TCP faces particular problems with, for example, route failure, channel contention and high bit error rates. These factors are responsible for the performance degradation of TCP in wireless ad hoc networks. The research community has produced a wide range of proposals to improve the performance of TCP in wireless ad hoc networks. This article presents a survey of these proposals (approaches). A classification of TCP improvement proposals for wireless ad hoc networks is presented, which makes it easy to compare the proposals falling under the same category. Tables which summarize the approaches for quick overview are provided. Possible directions for further improvements in this area are suggested in the conclusions. The aim of the article is to enable the reader to quickly acquire an overview of the state of TCP in wireless ad hoc networks.This study is partly funded by Kohat University of Science & Technology (KUST), Pakistan, and the Higher Education Commission, Pakistan

Prevalence of refractive errors in children in India: a systematic review

Uncorrected refractive error is an avoidable cause of visual impairment which affects children in India. The objective of this review is to estimate the prevalence of refractive errors in children ≤ 15 years of age. The Preferred Reporting Items for Systematic Reviews and Meta‐Analyses guidelines were followed in this review. A detailed literature search was performed to include all population and school‐based studies published from India between January 1990 and January 2017, using the Cochrane Library, Medline and Embase. The quality of the included studies was assessed based on a critical appraisal tool developed for systematic reviews of prevalence studies. Four population‐based studies and eight school‐based studies were included. The overall prevalence of refractive error per 100 children was 8.0 (CI: 7.4–8.1) and in schools it was 10.8 (CI: 10.5–11.2). The population‐based prevalence of myopia, hyperopia (≥ +2.00 D) and astigmatism was 5.3 per cent, 4.0 per cent and 5.4 per cent, respectively. Combined refractive error and myopia alone were higher in urban areas compared to rural areas (odds ratio [OR]: 2.27 [CI: 2.09–2.45]) and (OR: 2.12 [CI: 1.79–2.50]), respectively. The prevalence of combined refractive errors and myopia alone in schools was higher among girls than boys (OR: 1.2 [CI: 1.1–1.3] and OR: 1.1 [CI: 1.1–1.2]), respectively. However, hyperopia was more prevalent among boys than girls in schools (OR: 2.1 [CI: 1.8–2.4]). Refractive error in children in India is a major public health problem and requires concerted efforts from various stakeholders including the health care workforce, education professionals and parents, to manage this issue

Electric Elegance: Enhancing Cotton Fabric with Conducting Polypyrrole for Gas Sensing Applications

 This work is carried out to study the indigenously developed conducting polymer-based gas sensor for NO2 detection. The gas sensor is fabricated using conducting polymer such as Polypyrrole (PPy) as the active layer on the cotton fabric surface. The effects of washing on the composition and structure of samples were investigated through the application of XRD and FTIR spectroscopy. XRD analysis revealed notable changes in crystal structure. FTIR analysis provided insights into the molecular bonds present, highlighting variations in the functional groups before and after washing. We evaluated the electrical conductivities of samples before and after washing. The key findings shed light on the effects of washing on the chemical structure of gas-sensing materials, which is critical for maintaining sensor performance. This paper discusses the gas sensing mechanism and configuration of the sensor with a threshold limit value (TLV)  of 25 ppm, enabling detection at low ppm concentrations

Examining health-related quality of life in pediatric cancer patients with febrile neutropenia: Factors predicting poor recovery in children and their parents

Background The impact febrile neutropenia (FN) has on the health-related quality of life (HRQoL) of children with cancer and their families is poorly understood. We sought to characterize the course of child and parent HRQoL during and following FN episodes. Method Data on HRQoL were collected in the multisite Australian Predicting Infectious ComplicatioNs in Children with Cancer (PICNICC) study. Participants were enrolled between November 2016 to January 2018. The Child Health Utility (CHU9D) was used to assess HRQoL in children (N = 167 FN events) and the Assessment of Quality of Life (AQoL-8D) was used to assess HRQoL parents (N = 218 FN events) at three time points: 0–3 days, 7-days and 30-days following the onset of FN. Group-based trajectory modeling (GBTM) was used to characterize the course of HRQoL. Findings For children, three distinct groups were identified: persistently low HRQoL over the 30-day course of follow-up (chronic: N = 78/167; 47%), increasing HRQoL after the onset of FN to 30 days follow-up (recovering: N = 36/167; 22%), and persistently high HRQoL at all three timepoints (resilient: N = 53/167; 32%). Applying these definitions, parents were classified into two distinct groups: chronic (N = 107/218, 49%) and resilient (N = 111/218, 51%). The child being male, having solid cancer, the presence of financial stress, and relationship difficulties between the parent and child were significant predictors of chronic group membership for both parents and children. Children classified as high-risk FN were significantly more likely to belong to the recovery group. Being female, having blood cancers and the absence of financial or relationship difficulties were predictive of both parents and children being in the resilient group. Interpretation Approximately half the children and parents had chronically low HRQoL scores, which did not improve following resolution of the FN episode. The child's sex, cancer type, and presence of financial and relationship stress were predictive of chronic group membership for both parents and children. These families may benefit from increased financial and psychosocial support during anti-cancer treatment