Triplet lifetime in gaseous argon

MiniCLEAN is a single-phase liquid argon dark matter experiment. During the initial cooling phase, impurities within the cold gas ($<$140 K) were monitored by measuring the scintillation light triplet lifetime, and ultimately a triplet lifetime of 3.480 $\pm$ 0.001 (stat.) $\pm$ 0.064 (sys.) $\mu$s was obtained, indicating ultra-pure argon. This is the longest argon triplet time constant ever reported. The effect of quenching of separate components of the scintillation light is also investigated

Long Lasting Modulation of Cortical Oscillations after Continuous Theta Burst Transcranial Magnetic Stimulation

Transcranial magnetic theta burst stimulation (TBS) differs from other high-frequency rTMS protocols because it induces plastic changes up to an hour despite lower stimulus intensity and shorter duration of stimulation. However, the effects of TBS on neuronal oscillations remain unclear. In this study, we used electroencephalography (EEG) to investigate changes of neuronal oscillations after continuous TBS (cTBS), the protocol that emulates long-term depression (LTD) form of synaptic plasticity. We randomly divided 26 healthy humans into two groups receiving either Active or Sham cTBS as control over the left primary motor cortex (M1). Post-cTBS aftereffects were assessed with behavioural measurements at rest using motor evoked potentials (MEPs) and at active state during the execution of a choice reaction time (RT) task in combination with continuous electrophysiological recordings. The cTBS-induced EEG oscillations were assessed using event-related power (ERPow), which reflected regional oscillatory activity of neural assemblies of θ (4–7.5 Hz), low α (8–9.5 Hz), µ (10–12.5 Hz), low β (13–19.5 Hz), and high β (20–30 Hz) brain rhythms. Results revealed 20-min suppression of MEPs and at least 30-min increase of ERPow modulation, suggesting that besides MEPs, EEG has the potential to provide an accurate cortical readout to assess cortical excitability and to investigate the interference of cortical oscillations in the human brain post-cTBS. We also observed a predominant modulation of β frequency band, supporting the hypothesis that cTBS acts more on cortical level. Theta oscillations were also modulated during rest implying the involvement of independent cortical theta generators over the motor network post cTBS. This work provided more insights into the underlying mechanisms of cTBS, providing a possible link between synchronised neural oscillations and LTD in humans

Influence of data acquisition geometry on soybean spectral response simulated by the prosail model Influência da geometria de aquisição de dados na resposta espectral da soja simulada pelo modelo prosail

View angle and directional effects significantly affect reflectance and vegetation indices, especially when daily images collected by large field-of-view (FOV) sensors like the Moderate Resolution Imaging Spectroradiometer (MODIS) are used. In this study, the PROSAIL radiative transfer model was chosen to evaluate the impact of the geometry of data acquisition on soybean reflectance and two vegetation indices (Normalized Difference Vegetation Index - NDVI and Enhanced Vegetation Index -EVI) by varying biochemical and biophysical parameters of the crop. Input values for PROSAIL simulation were based on the literature and were adjusted by the comparison between simulated and real satellite soybean spectra acquired by the MODIS/Terra and hyperspectral Hyperion/Earth Observing-One (EO-1). Results showed that the influence of the view angle and view direction on reflectance was stronger with decreasing leaf area index (LAI) and chlorophyll concentration. Because of the greater dependence on the near-infrared reflectance, the EVI was much more sensitive to viewing geometry than NDVI presenting larger values in the backscattering direction. The contrary was observed for NDVI in the forward scattering direction. In relation to the LAI, NDVI was much more isotropic for closed soybean canopies than for incomplete canopies and a contrary behavior was verified for EVI.Os efeitos direcionais e de ângulo de visada afetam significativamente a reflectância e os índices de vegetação, especialmente quando são usadas imagens diárias adquiridas por sensores com amplo campo de visada como o Moderate Resolution Imaging Spectroradiometer (MODIS). No presente estudo, o modelo de transferência radiativa PROSAIL foi escolhido para avaliar o impacto da geometria de aquisição de dados na reflectância da soja e no cálculo de dois índices de vegetação (Normalized Difference Vegetation Index -NDVI e Enhanced Vegetation Index -EVI), variando-se parâmetros bioquímicos e biofísicos do dossel. Os valores usados para a simulação PROSAIL foram definidos com base na literatura e foram ajustados pela comparação entre espectros de soja simulados e adquiridos pelos sensores MODIS/Terra e hiperespectral Hyperion/Earth Observing-One (EO-1). Os resultados mostraram que os efeitos direcionais e de ângulo de visada na reflectância foram mais fortes com a diminuição do índice de área foliar (IAF) e da concentração de clorofila. Por ser mais dependente da banda do infravermelho próximo (IVP), o EVI foi muito mais sensível à geometria de visada do que o NDVI, apresentando maiores valores na direção do retroespalhamento. O contrário foi observado para o NDVI na direção do espalhamento frontal. Em relação ao IAF, o NDVI foi mais isotrópico para dosséis fechados de soja do que para dosséis esparsos, e um comportamento contrário foi verificado para o EVI

Vegetation indices for remote sensing of beans (Phaseolus vulgaris L.)

As aplicações de sensoriamento remoto em estudos de culturas agrícolas têm feito uso extensivo dos índices de vegetação (IVs). Constituídos de duas ou mais bandas, servem para realçar as feições de vegetação e ao mesmo tempo minimizar efeitos espúrios, como solos ou efeitos angulares, ou ainda efeitos atmosféricos. Não se formou ainda opinião unânime sobre as propriedades dos IVs, ou seja, não existe consenso sobre a utilização dos diversos IVs nas situações variadas que existem na natureza. Este trabalho visa fazer uma avaliação de três dos mais importantes IVs quanto a suas variações, em função de três parâmetros relevantes em sensoriamento remoto: solos, ângulos de visada e ângulos de iluminação, num experimento fatorial com feijão, em quatro estádios de desenvolvimento. Constatou-se que as influências dos fatores sobre as bandas individuais constituintes dos IVs foram relevantes na compreensão dos efeitos sobre os IVs. Os IVs apresentaram diferenças significativas quanto aos solos, nos quatro estádios de crescimento da cultura. Já o ângulo de visada influenciou de forma significativa o NDVI (índice de Vegetação Diferença Normalizada) no estádio inicial de crescimento do feijão. Os IVs não foram afetados quanto ao ângulo de iluminação, quando a cultura cobriu totalmente o solo. Além disso, houve saturação do NDVI, enquanto o SAVI (Índice de Vegetação Ajustado para Solo) e o PVI (índice de Vegetação Perpendicular) continuaram a responder aos tratamentos, principalmente em decorrência de suas sensibilidades ao infravermelho.Vegetation indices (VIs) are an important tool in remote sensing of vegetation. These VIs are composed of two or more single bands and they are supposed to minimize some intervening effects such as soil background, view and illumination angles and atmospheric effects. However, there is a lack of knowledge on how different VIs behave on a developing crop over different soils and submitted to different viewing conditions; the exact role the bands play in the VIs under those conditions is to be understood. This paper describes an experiment in which bean (Phaseolus vulgaris L.) was planted on the same soil, but in a changing three soil backgrounds, under two view angles and four times of the day, in four dates along the crop cycle, and in randomly blocks design. It is shown that the analysis of individual bands is very important for understanding the behavior of VIs. Soils were statistically significant in all stages analyzed for the three VIs; however, the view angle was significant only for NDVI and for low ground cover. The illumination angle was significant for all VIs and for all ground covers, except for 100%. Moreover, there was an expected NDVI saturation as the ground cover increased while the SAVI and PVI keep on responding to treatments, mainly in function of their sensitivities to near infrared

Computer aided analysis of cooling of electronic equipments

Açığa çıkan ısı miktarının yüksek olduğu elektronik cihazların soğutulmasında klasik yöntemler yetersiz kalabilmektedir. Bu durumda çarpan hava jeti ve sıvı soğutmalı sistemler ön plana çıkmaktadır. Fakat sıvı soğutmalı sistemlerin uygulamasında ortaya çıkan bazı sakıncalar nedeniyle çarpan hava jetleri ile soğutma cazip hale gelmektedir. Bu çalışmada öncelikle elektronik sistemlerin soğutulması hakkında detaylı bilgi verilmiştir. Ardından, elektronik bir kartı temsil eden bir levhanın yüzeye dik olarak çarpan hava jeti ile soğutulması durumunda, akış ve ısı transferi karakteristikleri hesaplamalı olarak analiz edilmiştir. Sabit ısı akışıyla ısıtılan levhanın, tekli ve çoklu jet kullanılarak soğutulması durumları ayrı ayrı ele alınmıştır. Akışın, türbülanslı, iki boyutlu, sıkıştırılamaz ve sürekli rejimde olduğu kabul edilmiştir. Analizde standart k-s türbülans modeli kullanılmış olup korunum denklemleri Galerkin Sonlu Elemanlar Metodu ile ANS YS-FLOTRAN paket programı kullanılarak çözülmüştür. Hesaplamalar 4<z/Dh<10 ve 4000<Re<12000 aralığında yapılmıştır. Havanın termofıziksel özelliklerinin sıcaklıkla değişimi ve kaldırma kuvveti etkileri de gözönüne alınmıştır. Analizler sonucunda artan Reynolds sayısı ve azalan z/Dh değerleriyle birlikte ısı transferinde kayda değer bir artış meydana geldiği görülmüştür. Tekli jet yerine aynı özelliklere sahip çoklu jet kullanılması durumunda ortalama Nusselt sayısında dolayısıyla ortalama ısı taşınım katsayısında yaklaşık %21 oranında artış meydana gelmiştir. Ayrıca türbülans şiddetindeki artışın çarpma noktasında ısı transferini arttırdığı gözlenmiştir. Elde edilen nümerik sonuçlar literatürdeki deneysel verilerle karşılaştırıldığında iyi bir uyumun sağlandığı tespit edilmiştir.Classical cooling methods can be insufficient in electronic equipments dissipating great deal of heat. In such cases, cooling with liquids and impinging air jets become important. But the problems occurred during the application of water cooling system make impinging air jets preferable. In this study, detailed information about cooling electronic systems was given first and then flow and heat transfer characteristics of plate representing an electronic card were analyzed computationally. It is assumed that the flow is turbulent, two- dimensional, incompressible and steady. Standard k-s turbulence model is used in the analyses and conservation equations are solved by using Galerkin Finite Element code ANSYS-FLOTRAN. Computations are performed in the ranges of 4<z/Dh<10 and 4000<Re<12000. The variation of thermo physical properties of air with temperature and buoyancy effects is considered. In the result of analysis, it is observed that an increase in heat transfer rate together with increasing Reynolds number and decreasing z/Dh ratio. In the case of double jets instead of single one, Nusselt number is increased approximately 21%. In addition, the increase in turbulence intensity makes heat transfer higher at impinging point. Finally, obtained results are compared and evaluated with experimental studies in literatüre

Spatial and temporal EEG-fMRI changes during preictal and postictal phases in a patient with posttraumatic epilepsy

The combined use of electroencephalography (EEG) and functional magnetic resonance imaging (EEG-fMRI) in epilepsy allows the noninvasive hemodynamic characterization of epileptic discharge-related neuronal activations. The aim of this study was to investigate pathophysiologic mechanisms underlying epileptic activity by exploring the spatial and temporal distribution of fMRI signal modifications during seizure in a single patient with posttraumatic epilepsy. EEG and fMRI data were acquired during two scanning sessions: a spontaneous critical episode was observed during the first, and interictal events were recorded during the second. The EEG-fMRI data were analyzed using the general linear model (GLM). Blood oxygenation level-dependent (BOLD) localization derived from the preictal and artifact-free postictal phase was concordant with the BOLD localization of the interictal epileptiform discharges identified in the second session, pointing to a left perilesional mesiofrontal area. Of note, BOLD signal modifications were already visible several seconds before seizure onset. In brief, BOLD activations from the preictal, postictal, and interictal epileptiform discharge analysis appear to be concordant with the clinically driven localization hypothesis, whereas a widespread network of activations is detected during the ictal phase in a partial seizure