A Statistical Theory of Avalanche Breakdown in Silicon

A statistical theory of avalanche breakdown in silicon is presented, based on the conventional Boltzmann transport equation. The scattering mechanisms considered are impact ionization (electron-hole pair production), phonon emission and absorption, thermal generation and recombination. The resultant critical field is found to depend on the recombination statistics, which were ignored in previous theories of avalanche breakdown. The theoretical temperature dependence is compared with the temperature dependence of the breakdown voltages of three conunercial diodes

Cancer and changes in facial appearance : a meta-ethnography of qualitative studies

Introduction: Living with an altered facial appearance as a result of treatment for cancer requires considerable psychological adjustment. As such it is essential that health care professionals understand the lived experience of people affected. This systematic review provides a metaethnography of studies that have explored the experience of changed facial appearance as a result of cancer. Methods: A search of four databases (Web of Science, CINAHL, PsycInfo and Scopus) took place using terms relating to qualitative research, cancer, and changed facial appearance. Thirteen studies were identified, appraised and included in the synthesis. The findings and interpretations within the studies were subject to meta-ethnography procedures so as to elicit novel cross cutting themes. Findings: The experience of changed facial appearance after cancer was clustered into three contexts. In the context of the disease, subthemes were the primacy of survival, the changing relationship with the disease and the impact of the care team on the experience of changed appearance. In the context of the social world, subthemes were positive reactions, negative reactions and coping strategies. In the context of the self, subthemes were the self under attack, self-to-self relating, the self in the world and rebuilding the self. Conclusions: The findings indicate that healthcare professionals must conduct holistic assessments, so as to fully recognise and where necessary address the impact upon self. The meta-ethnography shows that the experience of facial appearance change following cancer is complex and requires awareness of a number of theoretical areas including identity construction, social support, stigmatisation, and the specific literature on visible difference

To understand the current user profile of Leeds City Credit Union and examine the reasons for usage

The aim of this thesis is to understand, using detailed modelling, the users and their reasons for use of Leeds City Credit Union (LCCU) with implied application for other UK credit unions. With the initial aims resulting from a Knowledge Transfer Programme (KTP) between LCCU and the University of Leeds, this study has been performed using a case-study (LCCU) with the intention that the findings can be adapted to suit the needs and understanding of other UK credit unions, thus answer the broader research questions around credit union usage. The original contribution to knowledge is therefore the modelling relating to the users and usage of LCCU so that a detailed understanding of the user profile can be tailored and applied to other UK credit unions as niche financial service providers. The main source of data for this thesis was the analysis of a user and non-user questionnaire and this was supported by the use of focus groups. This data was then analysed using a range of techniques: qualitative analysis through the focus groups; descriptive analysis; factor analysis; and regression. From this analysis it was discovered that users are motivated to join LCCU for three key reasons. There are those who: use providers offering the best rates of return; support the ethical stance that the credit union movement offers; and who are financially excluded and unable to access credit elsewhere. Each of these three segments displayed unique profiling characteristics. In addition responses between users and non-users were also compared to identify the significant characteristics of users. These findings were contrary to the expectation that credit unions are just for the poorest sectors of society. This provides not only a unique academic insight in this niche financial services provider but also practically, in the development of a marketing strategy as defined by the KTP programme.EThOS - Electronic Theses Online ServiceGBUnited Kingdo

Morphology and connectivity of parabrachial and cortical inputs to gustatory thalamus in rats

The ventroposterior medialis parvocellularis (VPMpc) nucleus of the thalamus, the thalamic relay nucleus for gustatory sensation, receives primary input from the parabrachial nucleus, and projects to the insular cortex. To reveal the unique properties of the gustatory thalamus in comparison with archetypical sensory relay nuclei, this study examines the morphology of synaptic circuitry in the VPMpc, focusing on parabrachiothalamic driver input and corticothalamic feedback. Anterogradely visualized parabrachiothalamic fibers in the VPMpc bear large swellings. At electron microscope resolution, parabrachiothalamic axons are myelinated and make large boutons, forming multiple asymmetric, adherent, and perforated synapses onto large‐caliber dendrites and dendrite initial segments. Labeled boutons contain dense‐core vesicles, and they resemble a population of terminals within the VPMpc containing calcitonin gene‐related peptide. As is typical of primary inputs to other thalamic nuclei, parabrachiothalamic terminals are over five times larger than other inputs, while constituting only 2% of all synapses. Glomeruli and triadic arrangements, characteristic features of other sensory thalamic nuclei, are not encountered. As revealed by anterograde tracer injections into the insular cortex, corticothalamic projections in the VPMpc form a dense network of fine fibers bearing small boutons. Corticothalamic terminals within the VPMpc were also observed to synapse on cells that were retrogradely filled from the same injections. The results constitute an initial survey describing unique anatomical properties of the rodent gustatory thalamus. J. Comp. Neurol. 523:139–161, 2015. © 2014 Wiley Periodicals, Inc. Using biotinylated tract tracers and light and electron microscopy, the authors provide quantitative ultrastructural characterization of two inputs that arrive to the gustatory thalamic nucleus (ventroposterior medialis parvocellularis nucleus [VPMpc]): parabrachiothalamic axons that bring the primary input, and corticothalamic axons that provide the feedback input.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/109654/1/cne23673.pd

Anatomical connectivity patterns predict face selectivity in the fusiform gyrus

A fundamental assumption in neuroscience is that brain structure determines function. Accordingly, functionally distinct regions of cortex should be structurally distinct in their connections to other areas. We tested this hypothesis in relation to face selectivity in the fusiform gyrus. By using only structural connectivity, as measured through diffusion-weighted imaging, we were able to predict functional activation to faces in the fusiform gyrus. These predictions outperformed two control models and a standard group-average benchmark. The structure–function relationship discovered from the initial participants was highly robust in predicting activation in a second group of participants, despite differences in acquisition parameters and stimuli. This approach can thus reliably estimate activation in participants who cannot perform functional imaging tasks and is an alternative to group-activation maps. Additionally, we identified cortical regions whose connectivity was highly influential in predicting face selectivity within the fusiform, suggesting a possible mechanistic architecture underlying face processing in humans.United States. Public Health Service (DA023427)National Institute of Mental Health (U.S.) (F32 MH084488)National Eye Institute (T32 EY013935)Poitras FoundationSimons FoundationEllison Medical Foundatio

The Evolution of Social Orienting: Evidence from Chicks (Gallus gallus) and Human Newborns

Converging evidence from different species indicates that some newborn vertebrates, including humans, have visual predispositions to attend to the head region of animate creatures. It has been claimed that newborn preferences for faces are domain-relevant and similar in different species. One of the most common criticisms of the work supporting domain-relevant face biases in human newborns is that in most studies they already have several hours of visual experience when tested. This issue can be addressed by testing newly hatched face-na\uefve chicks (Gallus gallus) whose preferences can be assessed prior to any other visual experience with faces

Mammal-Like Organization of the Avian Midbrain Central Gray and a Reappraisal of the Intercollicular Nucleus

In mammals, rostrocaudal columns of the midbrain periaqueductal gray (PAG) regulate diverse behavioral and physiological functions, including sexual and fight-or-flight behavior, but homologous columns have not been identified in non-mammalian species. In contrast to mammals, in which the PAG lies ventral to the superior colliculus and surrounds the cerebral aqueduct, birds exhibit a hypertrophied tectum that is displaced laterally, and thus the midbrain central gray (CG) extends mediolaterally rather than dorsoventrally as in mammals. We therefore hypothesized that the avian CG is organized much like a folded open PAG. To address this hypothesis, we conducted immunohistochemical comparisons of the midbrains of mice and finches, as well as Fos studies of aggressive dominance, subordinance, non-social defense and sexual behavior in territorial and gregarious finch species. We obtained excellent support for our predictions based on the folded open model of the PAG and further showed that birds possess functional and anatomical zones that form longitudinal columns similar to those in mammals. However, distinguishing characteristics of the dorsal/dorsolateral PAG, such as a dense peptidergic innervation, a longitudinal column of neuronal nitric oxide synthase neurons, and aggression-induced Fos responses, do not lie within the classical avian CG, but in the laterally adjacent intercollicular nucleus (ICo), suggesting that much of the ICo is homologous to the dorsal PAG

Control of somatosensory cortical processing by thalamic posterior medial nucleus: A new role of thalamus in cortical function

This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.Current knowledge of thalamocortical interaction comes mainly from studying lemniscal thalamic systems. Less is known about paralemniscal thalamic nuclei function. In the vibrissae system, the posterior medial nucleus (POm) is the corresponding paralemniscal nucleus. POm neurons project to L1 and L5A of the primary somatosensory cortex (S1) in the rat brain. It is known that L1 modifies sensory-evoked responses through control of intracortical excitability suggesting that L1 exerts an influence on whisker responses. Therefore, thalamocortical pathways targeting L1 could modulate cortical firing. Here, using a combination of electrophysiology and pharmacology in vivo, we have sought to determine how POm influences cortical processing. In our experiments, single unit recordings performed in urethane- anesthetized rats showed that POm imposes precise control on the magnitude and duration of supra- and infragranular barrel cortex whisker responses. Our findings demonstrated that L1 inputs from POm imposed a time and intensity dependent regulation on cortical sensory processing. Moreover, we found that blocking L1 GABAergic inhibition or blocking P/Q-type Ca2+ channels in L1 prevents POm adjustment of whisker responses in the barrel cortex. Additionally, we found that POm was also controlling the sensory processing in S2 and this regulation was modulated by corticofugal activity from L5 in S1. Taken together, our data demonstrate the determinant role exerted by the POm in the adjustment of somatosensory cortical processing and in the regulation of cortical processing between S1 and S2. We propose that this adjustment could be a thalamocortical gain regulation mechanism also present in the processing of information between cortical areas.This work was supported by a grant from Ministerio de Economia y Competitividad (BFU2012- 36107