Characterization of Carbon-Contaminated B4C-Coated Optics after Chemically Selective Cleaning with Low-Pressure RF Plasma

Boron carbide (B4C) is one of the few materials that is expected to be mostly resilient with respect to the extremely high brilliance of the photon beam generated by free electron lasers (FELs) and is thus of considerable interest for optical applications in this field. However, as in the case of many other optics operated at modern light source facilities, B4C-coated optics are subject to ubiquitous carbon contaminations. These contaminations represent a serious issue for the operation of high performance FEL beamlines due to severe reduction of photon flux, beam coherence, creation of destructive interference, and scattering losses. A variety of B4C cleaning technologies were developed at different laboratories with varying success. We present a study regarding the low-pressure RF plasma cleaning of carbon contaminated B4C test samples via inductively coupled O2/Ar, H2/Ar, and pure O2 RF plasma produced following previous studies using the same IBSS GV10x downstream plasma source. Results regarding the chemistry, morphology as well as other aspects of the B4C optical coating before and after the plasma cleaning are reported. We conclude from these comparative plasma processes that pure O2 feedstock plasma only exhibits the required chemical selectivity for maintaining the integrity of the B4C optical coating.Comment: 27 pages, 15 figure

Nonadiabatic decoherence control of qubits strongly coupled to continuum edge

We propose a method for controlling the decoherence of a driven qubit that is strongly coupled to a reservoir, when the qubit resonance frequency is close to a continuum edge of the reservoir spectum. This strong-coupling regime is outside the scope of existing methods of decoherence control. We demonstate that an appropriate sequence of nearly abrupt changes of the resonance frequency can protect the qubit state from decay and decoherence more effectively than the intuitively obvious alternative, which is to fix the resonance well within a forbidden bandgap of the reservoir spectrum, as far as possible from the continuum edge. The "counterintuitive" nonadiabatic method outlined here can outperform its adiabatic counterparts in maintaining a high fidelity of quantum logic operations. The remarkable effectiveness of the proposed method, which requires much lower rates of frequency changes than previously proposed control methods, is due to the ability of appropriately alternating detunings from the continuum edge to augment the interference of the emitted and back-scattered quanta, thereby helping to stabilize the qubit state against decay. Applications to the control of decoherence near the edge of radiative, vibrational an photoionization continua are discussed.Comment: 7 pages, 4 figure

Electronically highly cubic conditions for Ru in alpha-RuCl3

We studied the local Ru 4d electronic structure of alpha-RuCl3 by means of polarization dependent x-ray absorption spectroscopy at the Ru-L2,3 edges. We observed a vanishingly small linear dichroism indicating that electronically the Ru 4d local symmetry is highly cubic. Using full multiplet cluster calculations we were able to reproduce the spectra excellently and to extract that the trigonal splitting of the t2g orbitals is -12 $\pm10$ meV, i.e. negligible as compared to the Ru 4d spin-orbit coupling constant. Consistent with our magnetic circular dichroism measurements, we found that the ratio of the orbital and spin moments is 2.0, the value expected for a Jeff = 1/2 ground state. We have thus shown that as far as the Ru 4d local properties are concerned, alpha-RuCl3 is an ideal candidate for the realization of Kitaev physics

Extended thromboprophylaxis with betrixaban in acutely ill medical patients

BACKGROUND: Patients with acute medical illnesses are at prolonged risk for venous thrombosis. However, the appropriate duration of thromboprophylaxis remains unknown. METHODS: Patients who were hospitalized for acute medical illnesses were randomly assigned to receive subcutaneous enoxaparin (at a dose of 40 mg once daily) for 10±4 days plus oral betrixaban placebo for 35 to 42 days or subcutaneous enoxaparin placebo for 10±4 days plus oral betrixaban (at a dose of 80 mg once daily) for 35 to 42 days. We performed sequential analyses in three prespecified, progressively inclusive cohorts: patients with an elevated d-dimer level (cohort 1), patients with an elevated d-dimer level or an age of at least 75 years (cohort 2), and all the enrolled patients (overall population cohort). The statistical analysis plan specified that if the between-group difference in any analysis in this sequence was not significant, the other analyses would be considered exploratory. The primary efficacy outcome was a composite of asymptomatic proximal deep-vein thrombosis and symptomatic venous thromboembolism. The principal safety outcome was major bleeding. RESULTS: A total of 7513 patients underwent randomization. In cohort 1, the primary efficacy outcome occurred in 6.9% of patients receiving betrixaban and 8.5% receiving enoxaparin (relative risk in the betrixaban group, 0.81; 95% confidence interval [CI], 0.65 to 1.00; P=0.054). The rates were 5.6% and 7.1%, respectively (relative risk, 0.80; 95% CI, 0.66 to 0.98; P=0.03) in cohort 2 and 5.3% and 7.0% (relative risk, 0.76; 95% CI, 0.63 to 0.92; P=0.006) in the overall population. (The last two analyses were considered to be exploratory owing to the result in cohort 1.) In the overall population, major bleeding occurred in 0.7% of the betrixaban group and 0.6% of the enoxaparin group (relative risk, 1.19; 95% CI, 0.67 to 2.12; P=0.55). CONCLUSIONS: Among acutely ill medical patients with an elevated d-dimer level, there was no significant difference between extended-duration betrixaban and a standard regimen of enoxaparin in the prespecified primary efficacy outcome. However, prespecified exploratory analyses provided evidence suggesting a benefit for betrixaban in the two larger cohorts. (Funded by Portola Pharmaceuticals; APEX ClinicalTrials.gov number, NCT01583218.)

Abortos por Trypanosoma vivax no Pantanal Mato-Grossense e Bolívia.

Existe um elevado número de espécies de tripanosomas descritos na literatura que infectam animais (Hoare, 1972; Clarkson, 1976; Desquesnes, 1997; Dávila, 2002). Porém, entre os tripanosomas que infectam animais de interesse na pecuária podemos citar: Trypanosoma vivax; T. evansi; T. equiperdum e T. theileri. O T. evansi tem ampla distribuição nas Américas, sendo encontrado no Panamá, Venezuela, Colômbia, Brasil, Bolívia, Paraguai, Argentina e Peru. O T. evansi e o T. vivax são um risco potencial para mais de 500 milhões de bovinos e 100 milhões de búfalos (Peregrine, 1994). Várias são as doenças que interferem no processo reprodutivo de animais domésticos. Dentre as enfermidades que provocam aborto e concorrem para a menor produtividade na fase de cria pode-se considerar a infecção pelo Trypanosoma vivax, tanto em bovinos (Seidl et al., 1999), quanto em ovinos (Bawa et al., 2000).bitstream/CPAP/55975/1/DOC75.pdfFormato Eletrônic

Caracterização socioeconômica das comunidades Chané/Bonfim, sub-região do Paraguai, Corumbá, MS.

Esse estudo caracteriza-se por ser um zoneamento das comunidades ribeirinhas da sub-região do Paraguai.bitstream/CPAP-2009-09/56843/1/CT82.pd

Área de ocorrência do mexilhão dourado (Limnoperna fortunei) na bacia do Alto Paraguai, entre os anos de 1998 e 2004.

O uso de água armazenada nos grandes navios marítimos para obter maior estabilidade, ajudar na propulsão e em manobras, a chamada "água de lastro", é o principal meio de introdução de organismos marinhos em ambientes aquáticos, tanto marinhos como de água doce. Em todo o mundo são transferidas anualmente cerca de 12 bilhões de toneladas de "água de lastro", que transportam aproximadamente 4.500 espécies diferentes. No Brasil, aproximadamente 95% de todo o comércio exterior é feito por via marítima e estima-se que 40.000 navios visitem os portos brasileiros anualmente, deslastrando 40 milhões de toneladas de água por ano (Silva & Souza, 2004). Pela "água de lastro" a espécie de bivale de água doce Limnoperna fortunei (Dunker, 1857) foi introduzida no estuário do rio da Prata, em 1991, provavelmente trazido por navios da Korea e Hong Kong (Pastorino et al., 1993). E a navegação no sistema Paraguai-Paraná foi o principal vetor da introdução desta espécie na Bacia do Alto Paraguai, onde foi observada pela primeira vez em 1998, no rio Paraguai, próximo à cidade de Corumba (MS).bitstream/item/39645/1/DOC64.pd