Nonrenewal spiking in Neural and Calcium signaling

Sowohl in der neuronalen als auch in der Kalzium Signalübertragung werden Informationen durch kurze Pulse oder Spikes, übertragen. Obwohl beide Systeme grundlegende Eigenschaften der Spike-Erzeugung teilen, wurden Integrate-and-fire (IF)-Modelle bisher nur auf neuronale Systeme angewendet. Diese Modelle bleiben auch dann behandelbar, wenn sie um Prozesse erweitert werden, die in Übereinstimmung mit Experimenten Spike-Zeiten mit korrelierten Interspike-Intervallen (ISI) erzeugen. Die statistische Analyse solcher nicht erneuerbarer Modelle ist Gegenstand dieser Arbeit. Das zweite Kapitel konzentriert sich auf die Berechnung des seriellen Korrelationskoeffizienten (SCC) in neuronalen Systemen. Es wird ein adaptives Modell betrachtet, das durch einen korrelierten Eingangsstrom getrieben wird. Es zeigt sich, dass neben den langsamen Prozessen auch die Dynamik des Modells den SCC bestimmt. Obwohl die Theorie für schwach gestörte IF-Modelle entwickelt wurde, kann sie auch auf stärker gestörte leitfähigkeitsbasierte Modelle angewendet werden und ist damit in der Lage, ein breites Spektrum biophysikalischer Situationen zu beschreiben. Im dritten Kapitel wird ein IF-Modell zur Beschreibung von Kalzium-Spikes formuliert, das die stochastische Freisetzung von Kalzium aus dem endoplasmatischen Retikulum (ER) und dessen Entleerung berücksichtigt. Die beobachtete Zeitskalentrennung zwischen Kalziumfreisetzung und Spikegenerierung motiviert eine Diffusionsnäherung, die eine analytische Behandlung des Modells ermöglicht. Die experimentell beobachtete Transiente, in der sich die ISIs einem stationären Wert annähern, kann durch die Entleerung des ER beschrieben werden. Es wird untersucht, wie die Statistiken der Transienten mit den stationären Intervallkorrelationen zusammenhängen. Es zeigt sich, dass eine stärkere Anpassung der Intervalle und eine kurze Transiente mit stärkeren Korrelationen einhergehen. Der Vergleich mit experimentellen Daten bestätigt diese Trends qualitativ.In both neuronal and calcium signaling, information is transmitted by short pulses, so-called spikes. Although both systems share some basic principles of spike generation, integrate-and-fire (IF) models have so far only been applied to neuronal systems. These models remain analytically tractable even when extended to include processes that lead to the generation of spike times with correlated interspike intervals (ISIs) as observed in experiments. The statistical analysis of such non-renewal models is the subject of this thesis. In the second chapter we focus on the calculation of the serial correlation coefficient (SCC) in neural systems. We consider an adaptive model driven by a correlated input current. We show that in addition to the two slow processes, the dynamics of the model also determines the SCC. Although the theory is developed for weakly perturbed IF models, it can also be applied to more strongly perturbed conductance-based models and is thus able to account for a wide range of biophysical situations. In the third chapter, we formulate an IF model to describe the generation of calcium spikes, taking into account the stochastic release of calcium from the endoplasmic reticulum (ER) and its depletion. The observed time-scale separation between calcium release and spike generation motivates a diffusion approximation that allows an analytical treatment of the model. The experimentally observed transient, during which the ISIs approach a steady state value, can be captured by the depletion of the ER. We study how the transient ISI statistics are related to the stationary interval correlations. We show that a stronger adaptation of the intervals as well as a short transient are associated with stronger interval correlations. Comparison with experimental data qualitatively confirms these trends

Montana Outfitters v. Fish and Game Commission: Of Elk and Equal Protection

Montana Outfitters v. Fish And Game Commission: Of Elk And Equal Protectio

Evaluating soil productivity and climate change benefits of woody biochar soil amendments for the US Interior West

2018 Summer.Includes bibliographical references.Managing our lands to provide for today and the future requires sustainable land management practices that enhance productivity while reducing climate impacts. Proponents claim biochar soil amendments offer a comprehensive solution to enhance soil capacity to deliver water and nutrients to plants while decreasing climate impacts through reduced nitrous oxide (N2O) emissions from fertilizer use and carbon (C) sequestration. This dissertation evaluates such claims for woody biochar applications within the US Interior West; to enhance crop production and reduce N2O emissions in deficit irrigation agricultural systems, and to support forest road restoration efforts. It also employs laboratory incubations and soil biogeochemical modeling to predict and to better understand the controls on biochar's greenhouse gas mitigation potential. The field studies demonstrate that this woody biochar improved soil moisture content but its enhanced capacity to retain water did not alleviate plant water stress when water inputs were low. Similarly, in forest soils, this woody biochar amendment improved plant available N but at levels that did not impact productivity. In lab incubations this woody biochar reduced N2O emissions. While this reduction could not be explained by bulk soil mineral N transformations, the soil moisture regime did affect biochar's ability to reduce N2O emissions. Despite the observed biochar N2O emission reductions in incubated soils, under field conditions biochar effects on N2O emissions were inconclusive. When evaluating biochar's C sequestration potential, soil biogeochemical modeling revealed that 59 percent of the biochar C applied will be sequestered in soils after 100 years. Losses from biochar fragmentation and leaching may constitute a considerable proportion of the C losses. Of the applications considered, C sequestration remains the most promising use for biochar soil amendments within the US Interior West

Perinatal characteristics and risk of polio among Swedish twins

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90577/1/j.1365-3016.2012.01268.x.pd

The steady state and response to a periodic stimulation of the firing rate for a theta neuron with correlated noise

The stochastic activity of neurons is caused by various sources of correlated fluctuations and can be described in terms of simplified, yet biophysically grounded, integrate-and-fire models. One paradigmatic model is the quadratic integrate-and-fire model and its equivalent phase description by the theta neuron. Here we study the theta neuron model driven by a correlated Ornstein-Uhlenbeck noise and by periodic stimuli. We apply the matrix-continued-fraction method to the associated Fokker-Planck equation to develop an efficient numerical scheme to determine the stationary firing rate as well as the stimulus-induced modulation of the instantaneous firing rate. For the stationary case, we identify the conditions under which the firing rate decreases or increases by the effect of the colored noise and compare our results to existing analytical approximations for limit cases. For an additional periodic signal we demonstrate how the linear and nonlinear response terms can be computed and report resonant behavior for some of them. We extend the method to the case of two periodic signals, generally with incommensurable frequencies, and present a particular case for which a strong mixed response to both signals is observed, i.e. where the response to the sum of signals differs significantly from the sum of responses to the single signals. We provide Python code for our computational method: https://github.com/jannikfranzen/theta_neuron.Peer Reviewe

Climate Commitment Case Study: Bridging Communication Silos in Higher Education for Impactful Digital Content Creation

Communications silos in higher education often negatively impact faculty, students, and staff, including communications professionals trying to create digital marketing content. When Duke University announced a university-wide climate commitment, the central communications office encouraged communications professionals across the university to promote the initiative. Central communications attempted to bridge silos and unite communicators across the university around a shared priority—this thesis examines the success of their campaign. Ten in-depth interviews were conducted with staff communications professionals at Duke University, inquiring about their views on the tactics employed to engage them in the Climate Commitment campaign. The communications professionals reported a lack of understanding on the goals of the campaign, connection to their audiences and priorities, and the metrics that would be used to measure success. As such, most communicators chose not to participate, or engaged at a minimum level. The deliverable of this paper illustrates a strategic communications plan for the Divinity School to engage in the campaign, including school staff and other communications professionals in the plan as an attempt to bridge silos—the plan was developed with the feedback on the initial campaign in mind.Master of Arts in Digital Communicatio

DEFECTIVE CALCIUM PUMPS IN NEURONS IN THE AGING BRAIN AND IN PARKINSON’S DISEASE

The plasma membrane Ca2+-ATPase (PMCA) pumps play an important role in the maintenance of precise levels of intracellular Ca2+, quintessential for the optimal functioning and long term survival of neurons. In this paper, we review evidence showing alterations in the PMCAs in aging brain. Additionally, we provide evidence showing defects in these transporters in Parkinson’s disease (PD). PMCA activity and protein levels in brain synaptic plasma membranes (SPMs) decline progressively with increasing age. The PMCAs undergo functional and structural changes when exposed to reactive oxygen species known to be generated in the aging brain and in neurodegenerative disorders such as PD. The major changes in the PMCAs include rapid inactivation, formation of aggregates, internalization from the plasma membrane and fragmentation by proteases. Reduction of PMCA levels as occurs in aging and under conditions of oxidative stress may play an important role in compromised neuronal function in the aging brain and in PD. Therapeutic strategies that protect the PMCAs and stabilize [Ca2+]i homeostasis have the potential of serving as novel interventions in preventing and/or slowing down the degeneration of neurons in various chronic neurodegenerative disorders

Projeto estrutural de edificação multifamiliar em concreto armado através do uso de procedimentos manuais e software comercial

TCC (graduação) - Universidade Federal de Santa Catarina. Centro Tecnológico. Engenharia Civil.Com o avanço da tecnologia e um mercado cada vez mais exigente, espera-se que engenheiros de estruturas consigam realizar projetos de forma cada vez mais eficiente, sempre assegurando a eficiência da edificação. Sendo assim, é cada vez mais comum o uso de softwares comerciais, que realizam a análise estrutural e dimensionamento de estruturas em um tempo muito reduzido, o que disponibiliza mais tempo para que os profissionais aperfeiçoem seus projetos. Porém, é ideal que o engenheiro não confie cegamente no software, e que tenha meios de verificar se os resultados obtidos fazem sentido de um ponto de vista prático. Essa conferência pode ser realizada seguindo os cálculos manuais apresentados em normas.O presente trabalho tem como objetivo comparar os resultados apresentados por diferentes métodos de cálculo. A primeira abordagem será o cálculo manual, realizado com o auxílio de planilhas eletrônicas e seguindo as premissas da NBR 6118:2014. Depois, a mesma estrutura foi dimensionada no software AltoQi Eberick 2018, e os resultados de ambos os métodos foram comparados e analisados

Estudo das barreiras na obtenção de órgãos para transplante nas unidades de terapia intensiva das regiões metropolitanas do Estado de Santa Catarina

Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências da Saúde. Programa de Pós-graduação em Ciências MédicasNesse período, foram detectados 225 pacientes com critérios para morte encefálica (Possíveis Doadores), todavia, foram testados apenas 105 pacientes (46,66%) (Potenciais Doadores), com aumento significativo de um ano para outro. A taxa de contra-indicações médicas foi de 21,90% sendo destes, 52,17% por falência médica, sem diferença significante de 1999 para 2000. A taxa de recusa familiar entre famílias questionadas for de 40,98% e sem diferença estatisticamente significante de um ano para o outro. No entanto, o aumento de Doadores Efetivos de 1999 para 2000 foi significante, uma vez que houve variação de 7(6,31%) para 19(16,67%). Constatou-se que o fator que realmente influenciou o número de Doadores Efetivos de um ano para outro, com taxas estáveis de negativa familiar e contra-indicações médicas, foi a realização de testes para morte encefálica pelos médicos intensivistas