A four-frame phase shift method insensitive to phase shifter nonlinearity

A four-frame phase shift method and an associated algorithm using unequal phase steps are presented. The unique advantage of this method is that it becomes insensitive to phase shifter nonlinearity because of the performance of a special procedure, in which the phase shifts are shared out between the reference beam and the object beam. By this means, any phase shifter can work as long as one phase shift is accurately known. On the basis of the technique, a simple calibration method for the linear phase shifter is suggested. The influences of phase shifter miscalibration, detector nonlinearity and random noise on the algorithm are investigated, and the optimal phase shifts are given.

Isotope shift measurements using k x-rays in Sn, Sm, and W

Electronic Kαl x-ray isotope shifts have been measured for Sn 116-124, Sm 148-154, W 182-184, W 184-186, and W 182-186 using a curved crystal Cauchois spectrometer. The analysis of the measurements has included the electrostatic volume effect, screening by the transition electron as well as the non-transition electrons, normal and specific mass shifts, dynamical nuclear qudrupole polarization, and a radiative correction effect of the electron magnetic moment in the nuclear charge radii are obtained. Where other experimental data are available, the agreement with the present measurements is satisfactory. Comparisons with several nuclear model predictions yield only partial agreement.

I. The crystal structure of potassium bis(tricyanovinyl)amine. II. Nuclear magnetic resonance studies of alkali halide solutions. III. Elucidation of the intramolecular hydrogen bond in acetylacetone by the deuterium isotope effect on the chemical shift of the bridge hydrogen

Part I

Potassium bis-(tricyanovinyl) amine, K⁺N[C(CN)=C(CN)₂]₂^-, crystallizes in the monoclinic system with the space group Cc and lattice constants, a = 13.346 ± 0.003 Å, c = 8.992 ± 0.003 Å, B = 114.42 ± 0.02°, and Z = 4. Three dimensional intensity data were collected by layers perpendicular to b* and c* axes. The crystal structure was refined by the least squares method with anisotropic temperature factor to an R value of 0.064.

The average carbon-carbon and carbon-nitrogen bond distances in –C-CΞN are 1.441 ± 0.016 Å and 1.146 ± 0.014 Å respectively. The bis-(tricyanovinyl) amine anion is approximately planar. The coordination number of the potassium ion is eight with bond distances from 2.890 Å to 3.408 Å. The bond angle C-N-C of the amine nitrogen is 132.4 ± 1.9°. Among six cyano groups in the molecule, two of them are bent by what appear to be significant amounts (5.0° and 7.2°). The remaining four are linear within the experimental error. The bending can probably be explained by molecular packing forces in the crystals.

Part II

The nuclear magnetic resonance of ⁸¹Br and ¹²⁷I in aqueous solutions were studied. The cation-halide ion interactions were studied by studying the effect of the Li⁺, Na⁺, K⁺, Mg⁺⁺, Cs⁺ upon the line width of the halide ions. The solvent-halide ion interactions were studied by studying the effects of methanol, acetonitrile, and acetone upon the line width of ⁸¹Br and ¹²⁷I in the aqueous solutions. It was found that the viscosity plays a very important role upon the halide ions line width. There is no specific cation-halide ion interaction for those ions such as Mg⁺⁺, Di⁺, Na⁺, and K⁺, whereas the Cs⁺ - halide ion interaction is strong. The effect of organic solvents upon the halide ion line width in aqueous solutions is in the order acetone ˃ acetonitrile ˃ methanol. It is suggested that halide ions do form some stable complex with the solvent molecules and the reason Cs⁺ can replace one of the ligands in the solvent-halide ion complex.

Part III

An unusually large isotope effect on the bridge hydrogen chemical shift of the enol form of pentanedione-2, 4(acetylacetone) and 3-methylpentanedione-2, 4 has been observed. An attempt has been made to interpret this effect. It is suggested from the deuterium isotope effect studies, temperature dependence of the bridge hydrogen chemical shift studies, IR studies in the OH, OD, and C=O stretch regions, and the HMO calculations, that there may probably be two structures for the enol form of acetylacetone. The difference between these two structures arises mainly from the electronic structure of the π-system. The relative population of these two structures at various temperatures for normal acetylacetone and at room temperature for the deuterated acetylacetone were calculated.

Isotope shift studies in the rare earths and lead

Isotope shifts of K_α1 x-ray transitions were measured for the Neodymium isotopes Nd 142, 143, 144, 145, 146, 148 and 150, the Samarium isotopes Sm 147, 148, 149, 150, 152 and 154, the Gadolinium isotopes Gd 154, 155, 156, 157, 158 and 160, the Dysprosium isotopes Dy 162 and 164, the Erbium isotopes Er 166, 168 and 170, the Hafnium isotopes Hf 178 and 180 and the Lead isotopes Pb 204, 206, 207 and 208. A curved crystal Cauchois spectrometer was used. The analysis of the measurement furnished the variation of the mean square charge radius of the nucleus, δ˂r²˃, for 23 isotope pairs. The experimental results were compared with theoretical values from nuclear models. Combining the x-ray shifts and the optical shifts in Nd and Sm yielded the optical mass shifts. An anomaly was observed in the odd-even shifts when the optical and the x-ray shifts were plotted against each other.

Gradient force pattern, focal shift, and focal switch in an apodized optical system

In this paper, the evolution of the gradient force pattern, focal shift, and focal switch induced by a three-portion pure phase-shifting apodizer is numerically investigated in detail. The results show that the proposed apodizer may induce tunable gradient force on the particles in the focal region, focal shift, and focal switch. By adjusting the geometrical parameters of the phase-shifting apodizer, multiple traps may occur with changeable distance between them, and the shape of the optical trap also evolves evidently. More interestingly, for certain geometrical parameters of the proposed apodizer, by changing the phase shift of inner annular portion, the considerable focal shift may occur with focal switch accompanying, which is discussed to show that this kind of apodizer may be a very promising method of transporting trapped particles. © 2005 Elsevier GmbH. All rights reserved.

Focal shift in focused radially polarized ultrashort pulsed laser beams

Beginning with a beam coherence polarization (BCP) matrix, we obtain an analytical intensity expression for radially polarized ultrashort pulsed laser beams that pass through an apertureless aplanatic lens. We also investigate the intensity distribution of radially polarized beams in the vicinity of the focus. The focal shift of these beams is studied in detail. The focal shift depends strongly on Z(F) that coincides with pi times the Fresnel number. (c) 2007 Optical Society of America.

O trabalho como metáfora da Educação

A exigência de lidar diretamente com a subjetividade faz com que a educação apresente características muito peculiares, que desbordam os limites de qualquer organização lógica. Essa tese põe no centro de suas reflexões os usos e limites das metáforas do mundo trabalho em sua função de modelar e, assim, explicar a atividade docente. Analisando as metáforas da tradição (a docência como sacerdócio e a professora como tia) e as metáforas da racionalização (o professor como especialista, trabalhador e profissional) procuramos mostrar que, à medida que a metáfora do trabalho foi se impregnando na escola, a atividade docente acabou por excluir do horizonte de suas preocupações teóricas a capacidade humana de iniciativa. Portando-se como doadora de sentido universal para as atividades humanas, a metáfora do trabalho, que não se reduz ao simples deslocamento de palavra, mas à transposição de um sentido enraizado, tornou-se excessiva e insuficiente para se pensar a tarefa da formação humana. Nesse sentido, a introdução do conceito de ação para elucidar a atividade docente surge com potencial representativo para a prática do professor, ali onde a metáfora do trabalho não consegue realizar plenamente.

Biodiversity as an index of regime shift in the eastern Bering Sea

Data collected from an annual groundf ish survey of the eastern Bering Sea shelf from 1975 to 2002 were used to estimate biomass and biodiversity indexes for two fish guilds: f latfish and roundfish. Biomass estimates indicated that several species of f latfish (particularly rock sole, arrowtooth flounder, and f lathead sole), several large sculpins (Myoxocephalus spp.), bigmouth (Hemitripterus bolini), and skates (Bathyraja spp.) had increased. Declining species included several f latfish species and many smaller roundfish species of sculpins, eelpouts (Lycodes spp.), and sablefish (Anoplopoma fimbria). Biodiversity indexes were calculated by using biomass estimates for both guilds from 1975 through 2002 within three physical domains on the eastern Bering Sea shelf. Biodiversity trends were found to be generally declining within the roundfish guild and generally increasing within the f latfish guild and varied between inner, middle, and outer shelf domains. The trends in biodiversity indexes from this study correlated strongly with the regime shift reported for the late 1970s and 1980s.

Seasonal marine growth of Bristol Bay sockeye salmon (Oncorhynchus nerka) in relation to competition with Asian pink salmon (O. gorbuscha) and the 1977 ocean regime shift

Recent research demonstrated significantly lower growth and survival of Bristol Bay sockeye salmon (Oncorhynchus nerka) during odd-numbered years of their second or third years at sea (1975, 1977, etc.), a trend that was opposite that of Asian pink salmon (O. gorbuscha) abundance. Here we evaluated seasonal growth trends of Kvichak and Egegik river sockeye salmon (Bristol Bay stocks) during even- and odd-numbered years at sea by measuring scale circuli increments within each g rowth zone of each major salmon age group between 1955 and 2000. First year scale growth was not significantly different between odd- and even-numbered years, but peak growth of age-2 smolts was significantly higher than age-1. smolts. Total second and third year scale growth of salmon was significantly lower during odd- than during even-numbered years. However, reduced scale growth in odd-numbered years began after peak growth in spring and continued through summer and fall even though most pink salmon had left the high seas by late July (10−18% growth reduction in odd vs. even years). The alternating odd and even year growth pattern was consistent before and after the 1977 ocean reg ime shift. During 1977−2000, when salmon abundance was relatively great, sockeye salmon growth was high during specific seasons compared with that during 1955−1976, that is to say, immediately after entry to Bristol Bay, after peak growth in the first year, during the middle of the second growing season, and during spring of the third season. Growth after the spring peak in the third year at sea was relatively low during 1977−2000. We hypothesize that high consumption rates of prey by pink salmon during spring through mid-July of odd-numbered years, coupled with declining zooplankton biomass during summer and potentially cyclic abundances of squid and other prey, contributed to reduced prey availability and therefore reduced growth of Bristol Bay sockeye salmon during late spring through fall of odd-numbered years.

Presenteísmo na enfermagem: repercussões para a saúde do trabalhador e a organização hospitalar

O presente estudo tem como objeto o presenteísmo em trabalhadores de enfermagem e as repercussões para a saúde do trabalhador e para a organização do trabalho. Considerando a natureza do objeto e as questões norteadoras, elaboraram-se os seguintes objetivos: Identificar a visão dos trabalhadores de enfermagem de um hospital geral sobre o presenteísmo na enfermagem; descrever os fatores que contribuem para o presenteísmo em trabalhadores de enfermagem de um hospital geral; e analisar as repercussões do presenteísmo para a saúde do trabalhador de enfermagem e para o processo de trabalho hospitalar. O estudo foi aprovado pelo Comitê de Ética em Pesquisa e protocolado com o número 419.673. Optou-se pelo método qualitativo do tipo exploratório e descritivo. O campo foi um hospital universitário situado no município do Rio de Janeiro. Participaram do estudo 39 trabalhadores de enfermagem (vinte e cinco técnicos de enfermagem e quatorze enfermeiros) lotados nas unidades de internação clínica. Na coleta dos dados, trabalhou-se com a técnica de entrevista do tipo semiestruturada mediante um roteiro, sendo os dados obtidos no mês de dezembro de 2013. Na caracterização dos entrevistados, utilizou-se um instrumento autoaplicado. No tratamento dos depoimentos recorreu-se à análise de conteúdo do tipo temática, que apontou os seguintes resultados: os participantes do estudo identificaram o presenteísmo no ambiente laboral, pelo fato de terem vários trabalhadores que comparecem ao serviço com problemas de saúde crônicos e agudos, que afetam a dinâmica e a qualidade do serviço ofertado. Diante desta realidade laboral, os trabalhadores se posicionam no sentido de manter a coesão grupal e acolher o trabalhador. No entanto, existe insatisfação por parte do grupo por se sentir sobrecarregado diante das demandas dos pacientes e demais atividades, sendo a qualidade do serviço afetada. Sobre os fatores que contribuem para o presenteísmo, identificou-se a precarização da força de trabalho, o comprometimento profissional com a instituição e os aspectos psicossociais; ou seja, fatores externos ao trabalho. Quanto às repercussões do presenteísmo para a saúde do trabalhador e o processo de trabalho, evidenciou-se que o presenteísmo é um fator que piora o estado de saúde do trabalhador, com necessidade de afastamento temporário do posto de trabalho e procura por atendimento médico durante o expediente. Como não há substituição de pessoal, a equipe tem de se reorganizar para atender as demandas de cunho técnico e assistencial, gerando conflitos no grupo. Conclui-se que, na visão dos trabalhadores o presenteísmo além de contribuir para a piora do estado de saúde do trabalhador, afeta negativamente o relacionamento interpessoal e a qualidade do serviço ofertado. Há necessidade de se diagnosticar e monitorar as condições de saúde dos trabalhadores por parte do Serviço de Saúde Ocupacional, através de exames admissionais e periódicos, de modo que sejam garantidos tratamento e acompanhamento adequados ao estado de saúde. Ratifica-se a relevância de condições de trabalho adequadas e que não exponham ainda mais os trabalhadores aos riscos presentes no ambiente laboral. Recomenda-se a continuidade de estudos sobre o presenteísmo tendo em vista o atual modelo neoliberal e o processo de precarização da força de trabalho no setor saúde.