Research of Quantum Well Laser Diode’s and Heterostructural P-I-N Photodiode’s of Fiber-Optic Modules Radiation Hardness to Gamma-ray and Neutron Irradiation

The paper presents the measurements results of optical and electrical parameters of quantum well laser diodes and heteroepitaxial photodiodes under gamma-ray and neutron irradiation. The testing results of transceiver modules gamma irradiation tolerance are introduced. The most vulnerable elements of module are highlighted. Keywords: laser diode, photodiode, radiation hardness, VCSEL, transceiver modules, fiber-optic communicatio

Small-worlds: How and why

We investigate small-world networks from the point of view of their origin. While the characteristics of small-world networks are now fairly well understood, there is as yet no work on what drives the emergence of such a network architecture. In situations such as neural or transportation networks, where a physical distance between the nodes of the network exists, we study whether the small-world topology arises as a consequence of a tradeoff between maximal connectivity and minimal wiring. Using simulated annealing, we study the properties of a randomly rewired network as the relative tradeoff between wiring and connectivity is varied. When the network seeks to minimize wiring, a regular graph results. At the other extreme, when connectivity is maximized, a near random network is obtained. In the intermediate regime, a small-world network is formed. However, unlike the model of Watts and Strogatz (Nature {\bf 393}, 440 (1998)), we find an alternate route to small-world behaviour through the formation of hubs, small clusters where one vertex is connected to a large number of neighbours.Comment: 20 pages, latex, 9 figure

Study of Gamma-ray Induced Attenuation of Fluorine-doped Single-mode Radiation Hard Optic Fiber

The paper presents the measurements results of optic fiber’s radiation induced attenuation. The approach of optic fiber’s radiation test at negative temperatures is introduced. The results of an investigation of the decay of an optical signal during a pulsed electron. Keywords: radiation hardness, fiber-optic communication, radiation-induced attenuatio

In Defence of Modest Doxasticism About Delusions

Here I reply to the main points raised by the commentators on the arguments put forward in my Delusions and Other Irrational Beliefs (OUP, 2009). My response is aimed at defending a modest doxastic account of clinical delusions, and is articulated in three sections. First, I consider the view that delusions are in-between perceptual and doxastic states, defended by Jacob Hohwy and Vivek Rajan, and the view that delusions are failed attempts at believing or not-quite-beliefs, proposed by Eric Schwitzgebel and Maura Tumulty. Then, I address the relationship between the doxastic account of delusions and the role, nature, and prospects of folk psychology, which is discussed by Dominic Murphy, Keith Frankish, and Maura Tumulty in their contributions. In the final remarks, I turn to the continuity thesis and suggest that, although there are important differences between clinical delusions and non-pathological beliefs, these differences cannot be characterised satisfactorily in epistemic terms. \u

The Right Diagnosis: The Role of Pathology in Health System Strengthening

Background: The drive to Universal Health Care coverage, and the need for strengthening health systems, has led to the examination of the role of core elements of the system such as surgery and radiology. Until recently, pathology (which, along with radiology, is key to correct diagnosis and treatment), has been relatively neglected within the global health framework. Resource-constrained governments and patients paying out-ofpocket have tended to underestimate the importance of laboratory testing. International donors have looked to point-of-care tests as a way to overcome the difficult task of strengthening national laboratory networks. Without strong pathology systems, however, there is the danger of development of multi-drug resistance, inaccurate tissue diagnosis and delays in identifying new emerging epidemics. Diagnosis and treatment of cancer and other non-communica

Experimental modulation of capsule size in Cryptococcus neoformans

Experimental modulation of capsule size is an important technique for the study of the virulence of the encapsulated pathogen Cryptococcus neoformans. In this paper, we summarize the techniques available for experimental modulation of capsule size in this yeast and describe improved methods to induce capsule size changes. The response of the yeast to the various stimuli is highly dependent on the cryptococcal strain. A high CO(2) atmosphere and a low iron concentration have been used classically to increase capsule size. Unfortunately, these stimuli are not reliable for inducing capsular enlargement in all strains. Recently we have identified new and simpler conditions for inducing capsule enlargement that consistently elicited this effect. Specifically, we noted that mammalian serum or diluted Sabouraud broth in MOPS buffer pH 7.3 efficiently induced capsule growth. Media that slowed the growth rate of the yeast correlated with an increase in capsule size. Finally, we summarize the most commonly used media that induce capsule growth in C. neoformans

Geometry of River Networks I: Scaling, Fluctuations, and Deviations

This article is the first in a series of three papers investigating the detailed geometry of river networks. Large-scale river networks mark an important class of two-dimensional branching networks, being not only of intrinsic interest but also a pervasive natural phenomenon. In the description of river network structure, scaling laws are uniformly observed. Reported values of scaling exponents vary suggesting that no unique set of scaling exponents exists. To improve this current understanding of scaling in river networks and to provide a fuller description of branching network structure, we report here a theoretical and empirical study of fluctuations about and deviations from scaling. We examine data for continent-scale river networks such as the Mississippi and the Amazon and draw inspiration from a simple model of directed, random networks. We center our investigations on the scaling of the length of sub-basin's dominant stream with its area, a characterization of basin shape known as Hack's law. We generalize this relationship to a joint probability density and show that fluctuations about scaling are substantial. We find strong deviations from scaling at small scales which can be explained by the existence of linear network structure. At intermediate scales, we find slow drifts in exponent values indicating that scaling is only approximately obeyed and that universality remains indeterminate. At large scales, we observe a breakdown in scaling due to decreasing sample space and correlations with overall basin shape. The extent of approximate scaling is significantly restricted by these deviations and will not be improved by increases in network resolution.Comment: 16 pages, 13 figures, Revtex4, submitted to PR

Mesoscopic organization reveals the constraints governing C. elegans nervous system

One of the biggest challenges in biology is to understand how activity at the cellular level of neurons, as a result of their mutual interactions, leads to the observed behavior of an organism responding to a variety of environmental stimuli. Investigating the intermediate or mesoscopic level of organization in the nervous system is a vital step towards understanding how the integration of micro-level dynamics results in macro-level functioning. In this paper, we have considered the somatic nervous system of the nematode Caenorhabditis elegans, for which the entire neuronal connectivity diagram is known. We focus on the organization of the system into modules, i.e., neuronal groups having relatively higher connection density compared to that of the overall network. We show that this mesoscopic feature cannot be explained exclusively in terms of considerations, such as optimizing for resource constraints (viz., total wiring cost) and communication efficiency (i.e., network path length). Comparison with other complex networks designed for efficient transport (of signals or resources) implies that neuronal networks form a distinct class. This suggests that the principal function of the network, viz., processing of sensory information resulting in appropriate motor response, may be playing a vital role in determining the connection topology. Using modular spectral analysis, we make explicit the intimate relation between function and structure in the nervous system. This is further brought out by identifying functionally critical neurons purely on the basis of patterns of intra- and inter-modular connections. Our study reveals how the design of the nervous system reflects several constraints, including its key functional role as a processor of information.Comment: Published version, Minor modifications, 16 pages, 9 figure

Genetic predictors of chronic heart failure in obese patients

BACKGROUND: the study of molecular genetic markers and pathogenetic mechanisms of neurohormonal activation, as well as their importance in the formation of heart failure in obesity, is an urgent problem of modern medicine, the solution of which will allow effective prevention of cardiovascular complications, optimize treatment and improve the prognosis of obese patients. AIMS: search for genetic markers presumably involved in the pathogenesis of secondary diastolic heart failure in patients with obesity. MATERIALS AND METHODS: PCR-diagnostics of whole blood of 104 patients with obesity was carried out, which were divided into 2 groups, depending on the presence of diastolic heart failure. The following candidate genes were analyzed: angiotensinogen AGT gene (C521T and T704C), angiotensin II receptor gene of the first type AGTR1 (A1166C), angiotensin II receptor gene of the second type AGTR2 (G1675A), aldosterone synthase gene CYP11B2 (C (-344) T). RESULTS: It is shown that the development of secondary diastolic heart failure in obese individuals of both sexes is associated with the mutation of the aldosterone synthase gene CYP11B2, namely, with the replacement of the C allele at the -344 position by the T allele and the presence of the T / T genotype. The relative risk of developing the disease with the T / T genotype was 5.93 times higher in men (p = 0.008) and 4.57 times in women (p = 0.014). For men, the mutation of the angiotensinogen AGT gene, namely the replacement of the allele C at position 521 by the T allele, is important. At the same time, the relative risk of development of SDS in the T / T genotype is increased by 4.26 times (p = 0.039). Mutations of the genes of the angiotensin II receptor of the first type AGTR1 (A1166C) and the angiotensin II receptor of the second type AGTR2 (G1675A) are not associated with the development of diastolic heart failure in obese patients. CONCLUSIONS: The data presented can be used to stratify the risk of secondary heart failure in obese individuals