Role of Proteome Physical Chemistry in Cell Behavior.

We review how major cell behaviors, such as bacterial growth laws, are derived from the physical chemistry of the cell's proteins. On one hand, cell actions depend on the individual biological functionalities of their many genes and proteins. On the other hand, the common physics among proteins can be as important as the unique biology that distinguishes them. For example, bacterial growth rates depend strongly on temperature. This dependence can be explained by the folding stabilities across a cell's proteome. Such modeling explains how thermophilic and mesophilic organisms differ, and how oxidative damage of highly charged proteins can lead to unfolding and aggregation in aging cells. Cells have characteristic time scales. For example, E. coli can duplicate as fast as 2-3 times per hour. These time scales can be explained by protein dynamics (the rates of synthesis and degradation, folding, and diffusional transport). It rationalizes how bacterial growth is slowed down by added salt. In the same way that the behaviors of inanimate materials can be expressed in terms of the statistical distributions of atoms and molecules, some cell behaviors can be expressed in terms of distributions of protein properties, giving insights into the microscopic basis of growth laws in simple cells

Performing edge detection by difference of Gaussians using q-Gaussian kernels

In image processing, edge detection is a valuable tool to perform the extraction of features from an image. This detection reduces the amount of information to be processed, since the redundant information (considered less relevant) can be unconsidered. The technique of edge detection consists of determining the points of a digital image whose intensity changes sharply. This changes are due to the discontinuities of the orientation on a surface for example. A well known method of edge detection is the Difference of Gaussians (DoG). The method consists of subtracting two Gaussians, where a kernel has a standard deviation smaller than the previous one. The convolution between the subtraction of kernels and the input image results in the edge detection of this image. This paper introduces a method of extracting edges using DoG with kernels based on the q-Gaussian probability distribution, derived from the q-statistic proposed by Constantino Tsallis. To demonstrate the method's potential, we compare the introduced method with the traditional DoG using Gaussians kernels. The results showed that the proposed method can extract edges with more accurate details.Comment: 5 pages, 5 figures, IC-MSQUARE 201

Access to HIV prevention and care for HIV-exposed and HIV-infected children : a qualitative study in rural and urban Mozambique

Background: Follow-up of HIV-exposed children for the delivery of prevention of mother-to-child transmission services and for early diagnosis and treatment of HIV infection is critical to their survival. Despite efforts, uptake of postnatal care for these children remains low in many sub-Saharan African countries. Methods: A qualitative study was conducted in three provinces in Mozambique to identify motivators and barriers to improve uptake of and retention in HIV prevention, care and treatment services for HIV-exposed and HIV-infected children. Participant recommendations were also gathered. Individual interviews (n = 79) and focus group discussions (n = 32) were conducted with parents/caregivers, grandmothers, community leaders and health care workers. Using a socioecological framework, the main themes identified were organized into multiple spheres of influence, specifically at the individual, interpersonal, institutional, community and policy levels. Results: Study participants reported factors such as seeking care outside of the conventional health system and disbelief in test results as barriers to use of HIV services. Other key barriers included fear of disclosure at the interpersonal level and poor patient flow and long waiting time at the institutional level. Key facilitators for accessing care included having hope for children's future, symptomatic illness in children, and the belief that health facilities were the appropriate places to get care. Conclusions: The results suggest that individual-level factors are critical drivers that influence the health-seeking behavior of caregivers of HIV-exposed and HIV-infected children in Mozambique. Noted strategies are to provide more information and awareness on the benefits of early pediatric testing and treatment with positive messages that incorporate success stories, to reach more pregnant women and mother-child pairs postpartum, and to provide counseling during tracing visits. Increasing uptake and retention may be achieved by improving patient flow at the institutional level at health facilities, by addressing concerns with family decision makers, and by working with community leaders to support the uptake of services for HIV-exposed children for essential preventive care