Optical investigation of the charge-density-wave phase transitions in NbSe3NbSe_{3}

We have measured the optical reflectivity $R(\omega)$ of the quasi one-dimensional conductor $NbSe_{3}$ from the far infrared up to the ultraviolet between 10 and 300 $K$ using light polarized along and normal to the chain axis. We find a depletion of the optical conductivity with decreasing temperature for both polarizations in the mid to far-infrared region. This leads to a redistribution of spectral weight from low to high energies due to partial gapping of the Fermi surface below the charge-density-wave transitions at 145 K and 59 K. We deduce the bulk magnitudes of the CDW gaps and discuss the scattering of ungapped free charge carriers and the role of fluctuations effects

Semiclassical model of ultrafast photoisomerization reactions

In this letter we propose a model which explains ultrafast and efficient photoisomerization reactions as driven by transitions between quasistationary states of one dimensional (1D) double well potential of an excited electronic state. This adiabatic potential is formed as a result of doubly crossing of a decay diabatic potential of the ground electronic state and a bound diabatic potential of the excited state. We calculate the eigenstates and eigenfunctions using the semiclassical connection matrices at the turning and crossing points and the shift matrices between these points. The transitions between the localized in the wells below the adiabatic barrier states are realized by the tunneling and by the double non-adiabatic transitions via the crossing points processes. Surprisingly the behavior with the maximum transition rate keeps going even for the states relatively far above the barrier (2 -4 times the barrier height). Even though a specific toy model is investigated here, when properly interpreted it yields quite reasonable values for a variety of measured quantities, such as a reaction quantum yield, and conversion time.Comment: 9 pages, 5 figures. accepted to Chem. Phys. Letters (2005

Velocity-space sensitivity of the time-of-flight neutron spectrometer at JET

The velocity-space sensitivities of fast-ion diagnostics are often described by so-called weight functions. Recently, we formulated weight functions showing the velocity-space sensitivity of the often dominant beam-target part of neutron energy spectra. These weight functions for neutron emission spectrometry (NES) are independent of the particular NES diagnostic. Here we apply these NES weight functions to the time-of-flight spectrometer TOFOR at JET. By taking the instrumental response function of TOFOR into account, we calculate time-of-flight NES weight functions that enable us to directly determine the velocity-space sensitivity of a given part of a measured time-of-flight spectrum from TOFOR

On the mechanisms governing gas penetration into a tokamak plasma during a massive gas injection

A new 1D radial fluid code, IMAGINE, is used to simulate the penetration of gas into a tokamak plasma during a massive gas injection (MGI). The main result is that the gas is in general strongly braked as it reaches the plasma, due to mechanisms related to charge exchange and (to a smaller extent) recombination. As a result, only a fraction of the gas penetrates into the plasma. Also, a shock wave is created in the gas which propagates away from the plasma, braking and compressing the incoming gas. Simulation results are quantitatively consistent, at least in terms of orders of magnitude, with experimental data for a D 2 MGI into a JET Ohmic plasma. Simulations of MGI into the background plasma surrounding a runaway electron beam show that if the background electron density is too high, the gas may not penetrate, suggesting a possible explanation for the recent results of Reux et al in JET (2015 Nucl. Fusion 55 093013)

Optimized workflow for on-line derivatization for targeted metabolomics approach by gas chromatography-mass spectrometry

Using manual derivatization in gas chromatography-mass spectrometry samples have varying equilibration times before analysis which increases technical variability and limits the number of potential samples analyzed. By contrast, automated derivatization methods can derivatize and inject each sample in an identical manner. We present a fully automated (on-line) derivatization method used for targeted analysis of different matrices. We describe method optimization and compare results from using off-line and on-line derivatization protocols, including the robustness and reproducibility of the methods. Our final parameters for the derivatization process were 20 µL of methoxyamine (MeOx) in pyridine for 60 min at 30 °C followed by 80 µL N-Methyl-N-trimethylsilyltrifluoracetamide (MSTFA) for 30 min at 30 °C combined with 4 h of equilibration time. The repeatability test in plasma and liver revealed a median relative standard deviation (RSD) of 16% and 10%, respectively. Serum samples showed a consistent intra-batch median RSD of 20% with an inter-batch variability of 27% across three batches. The direct comparison of on-line versus off-line demonstrated that on-line was fit for purpose and improves repeatability with a measured median RSD of 11% compared to 17% using the same method off-line. In summary, we recommend that optimized on-line methods may improve results for metabolomics and should be used where available

Relationship of edge localized mode burst times with divertor flux loop signal phase in JET

A phase relationship is identified between sequential edge localized modes (ELMs) occurrence times in a set of H-mode tokamak plasmas to the voltage measured in full flux azimuthal loops in the divertor region. We focus on plasmas in the Joint European Torus where a steady H-mode is sustained over several seconds, during which ELMs are observed in the Be II emission at the divertor. The ELMs analysed arise from intrinsic ELMing, in that there is no deliberate intent to control the ELMing process by external means. We use ELM timings derived from the Be II signal to perform direct time domain analysis of the full flux loop VLD2 and VLD3 signals, which provide a high cadence global measurement proportional to the voltage induced by changes in poloidal magnetic flux. Specifically, we examine how the time interval between pairs of successive ELMs is linked to the time-evolving phase of the full flux loop signals. Each ELM produces a clear early pulse in the full flux loop signals, whose peak time is used to condition our analysis. The arrival time of the following ELM, relative to this pulse, is found to fall into one of two categories: (i) prompt ELMs, which are directly paced by the initial response seen in the flux loop signals; and (ii) all other ELMs, which occur after the initial response of the full flux loop signals has decayed in amplitude. The times at which ELMs in category (ii) occur, relative to the first ELM of the pair, are clustered at times when the instantaneous phase of the full flux loop signal is close to its value at the time of the first ELM

Track D Social Science, Human Rights and Political Science

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/138414/1/jia218442.pd

Urolitíase: estudo comparativo em bovinos Guzerá oriundos de propriedades com e sem o problema

Diversos fatores podem contribuir para a formação de cálculos urinários, dentre estes, o desequilíbrio nutricional e a dureza da água consumida pelos ruminantes. O objetivo deste estudo foi identificar as características de propriedades que predispõem à urolitíase, através da avaliação da água, da dieta e determinações séricas e urinárias de cálcio, fósforo, magnésio, cloretos, sódio, potássio, cálculo da excreção fracionada (EF) dos eletrólitos, e da creatinina, proteína total, albumina e globulinas séricas. Foram colhidas amostras de sangue e urina de bovinos, Guzerá, criados semi intensivamente, distribuídos por dois grupos. O primeiro denominado grupo urolitíase (Gu), composto de animais com histórico, sinais clínicos e confirmação ultrassonográfica que apresentavam urolitíase; o segundo: grupo controle (Gc), sem histórico, nem sintomas da doença. Os bovinos do grupo urolitíase consumiam água com dureza total na concentração de 166,0mg CaCO3/L. A dieta dos animais do Gu apresentava maior concentração de fósforo e relação Ca:P inadequada. Os teores de fósforo sérico e urinário dos animais do Gu foram maiores do que os do Gc, assim como a concentração sérica de magnésio (p0,05), mas houve diminuição significativa nas EFs de magnésio, cloretos e de potássio do grupo urolitíase (p<0,05). A união destes fatores contribuiu para a ocorrência da urolitíase, sendo dureza total da água e a alta concentração de fósforo na dieta os principais fatores na gênese dos cálculos em bovinos