Dynamics of Counterion Condensation

Using a generalization of the Poisson-Boltzmann equation, dynamics of counterion condensation is studied. For a single charged plate in the presence of counterions, it is shown that the approach to equilibrium is diffusive. In the far from equilibrium case of a moving charged plate, a dynamical counterion condensation transition occurs at a critical velocity. The complex dynamic behavior of the counterion cloud is shown to lead to a novel nonlinear force-velocity relation for the moving plate.Comment: 5 pages, 1 ps figure included using eps

REGISTERS OF SEMIOTIC REPRESENTATIONS AIDING THE LEARNING OF COMBINATORIAL SITUATIONS

In order to analyze advances in the resolution of combinatorial situations, due to the identification, conversion and treatment of semiotic registers, two studies were carried out. In the first study, 5th grade students identified, from problems in natural language, registers in trees of possibilities, lists and numerical expressions. The second study, carried out with 5th, 7th and 9th grade students, was configured as an intervention study in which trees or lists were used as an intermediate representation of the departure register (natural language) to the arrival register (numerical expression). The results of the studies confirmed the hypothesis that the conversion to numerical expression is more complex than the conversion to trees or lists. It was also confirmed that trees are more congruent, than lists, with registers in numerical expression. It is concluded that the use of intermediate representations, such as trees or systematic lists, is a good teaching strategy for advances in the combinatorial reasoning of students in the early and middle years of schooling

Quantitative study of molecular N_2 trapped in disordered GaN:O films

The structure of disordered GaN:O films grown by ion-assisted deposition is investigated using x-ray absorption near-edge spectroscopy and Raman spectroscopy. It is found that between 4 and 21 % of the nitrogen in the films is in the form of molecular N_2 that interacts only weakly with the surrounding matrix. The anion to cation ratio in the GaN:O host remains close to unity, and there is a close correlation between the N_2 fraction, the level of oxygen impurities, and the absence of short-range order in the GaN:O matrix.Comment: 5 pages, 3 figure

Desempenho de bezerras leiteiras alimentadas com concentrado inicial contendo sais de ácidos orgânicos ou monesina.

O objetivo deste trabalho foi avaliar o efeito da inclusão de butirato de sódio, monensina sódica e propionato de cálcio no concentrado inicial sobre o desempenho de bezerras leiteiras antes e após o desaleitamento. Vinte e quatro bezerras Holandesas recém-nascidas foram alocadas em abrigos individuais até a décima semana de vida tendo livre acesso à água, alimentadas com 4L de leite/dia, em duas refeições, sendo bloqueadas em função do peso ao nascer a um dos tratamentos, de acordo com o aditivo no concentrado: 1)Butirato de sódio (0,15%); 2)Monensina sódica (30 ppm); 3)Propionato de cálcio (0,15%). Durante 10 semanas os animais receberam concentrado inicial até 2 kg/d e receberam também feno de capim-coast-cross à vontade após o desaleitamento. Semanalmente, os animais foram pesados e avaliados quanto à altura da cernelha, largura do traseiro e perímetro torácico. Não foram observados efeitos significativos entre os tratamentos para o consumo de concentrado e de feno, peso vivo e ganho de peso diário dos animais (P>0,05), entretanto foram observados efeitos de idade (P0,05). A inclusão dos aditivos resultou em desempenho satisfatório de bezerras leiteiras antes e após o desaleitamento. A monensina sódica pode ser substituída por sais de ácidos orgânicos sem prejuízo ao desempenho de bezerros

Effects of ON and OFF subthalamic nucleus-DBS on prefrontal cortex activation during a cognitive task: an fNIRS study

Subthalamic nucleus (STN) deep brain stimulation (DBS) therapy is an effective treatment for the appendicular motor symptoms of Parkinson’s disease (PD). The STN contains multiple segregated circuits subserving motor, cognitive and mood functions through distinct connectivity to cortical regions. Therefore, we examined prefrontal cortical (PFC) effects of “ON” and “OFF” STN-DBS on executive function (Go/NoGo) using functional near-infrared spectroscopy (fNIRS). Methods Out of 8 PD STN-DBS patients, we present here preliminary analysis of a male (62y) PD patient with bilateral STN-DBS (unipolar, 180Hz, 3.5V). The patient was tested after 12h withdrawal of dopamine medications in both an “OFF” and “ON” DBS session separated by 30min. The subject performed a computerised GoNoGo task with 3 alternating Go/NoGo blocks of 30s duration (20 trials/block) interspersed with 30s rest. Reaction time (RT) and accuracy (omission-Om and commission-Cm errors) results were the average of the 3 Go/NoGo blocks. During performance of the Go/NoGo blocks, changes in oxygenated (O2Hb) and deoxygenated (HHb) haemoglobin concentrations were measured by a fNIRS system (Oxymon MkIII, Artinis Medical Systems) covering the bilateral PFC regions. Results/Discussion Clinical motor performance (UPDRSIII) improved from OFF (31) to ON (20). RT during Go and NoGo was ∼40ms faster in OFF (460 and 364ms) than ON (516 and 407ms). Furthermore, the NoGo condition increased misses (Om) in ON (7%) than OFF (0%); while false alarms (Cm) were similarly increased in ON (27%) and OFF (30%). The Go and NoGo conditions increased bilateral PFC activation (i.e., increase in O2Hb and decrease in HHb). However, there was a general decrease in PFC activation in OFF relative to ON, and this was more obvious in Go than NoGo (see Fig. 1) Conclusion These preliminary results indicate that STN-DBS modulates neurovascular responses in the bilateral PFC that are associated with response inhibition

Teleophthalmology Support for Primary Care Diagnosis and Management

This study was performed to evaluate a healthcare strategy based on teleophthalmology for diagnosis and management of primary healthcare users. A descriptive cross-sectional study was conducted to review the medical records of patients from January 2013 to December 2014 from primary care units in the city of São Paulo. The units referred patients, who had diabetes or high blood pressure, and were users of chloroquine compounds, for a fundus examination. The images were sent to a reading center for review, diagnosis, and patient referrals. From 9173 analyzed patients, 570 (6.2%) were excluded because of poor image quality. Of the remaining patients, 4933 (57.3%) had diabetes, 7242 (84,2%) systemic hypertension, and 113 (1.3%) used chloroquine. Of these, 989 (11.5%) patients needed ophthalmologic treatment. The most frequently prescribed treatments were cataract extraction in 692 (70%) of 989 and photocoagulation in 245 (24.8%) of 989 cases. Overall, cataract extraction was indicated in 692 (8%) of 8603 cases and photocoagulation in 245 (2.8%) of 8603 cases. When only patients with diabetes were considered, the indication for photocoagulation increased to 4.5%.The results showed that non-medical professionals could produce good-quality ocular images for screening of ocular diseases in most cases; only 6.2% of ocular images did not meet quality requirements. Most patients referred for fundus examination did not need a specific treatment, indicating that this system could be an inexpensive and reliable tool for use in developing countries.Â

Diferentes teores de proteína metabolizável em rações com cana-de-açúcar para vacas em lactação.

O presente trabalho teve como objetivo avaliar o efeito de diferentes teores de proteína metabolizável (PM) na ração de vacas lactantes alimentadas com cana-de-açúcar

Pressure and chemical substitution effects in the local atomic structure of BaFe2As2

The effects of K and Co substitutions and quasi-hydrostatic applied pressure (P<9 GPa) in the local atomic structure of BaFe2As2, Ba(Fe{0.937}Co{0.063})2As2 and Ba{0.85}K{0.15}Fe2As2 superconductors were investigated by extended x-ray absorption fine structure (EXAFS) measurements in the As K absorption edge. The As-Fe bond length is found to be slightly reduced (<~ 0.01 Angstroms) by both Co and K substitutions, without any observable increment in the corresponding Debye Waller factor. Also, this bond is shown to be compressible (k = 3.3(3)x10^{-3} GPa^{-1}). The observed contractions of As-Fe bond under pressure and chemical substitutions are likely related with a reduction of the local Fe magnetic moments, and should be an important tuning parameter in the phase diagrams of the Fe-based superconductors.Comment: 7 pages, 6 figure

High pressure and high magnetic field studies of the electronic transport properties of the antiferromagnet Eu3ir4sn13

In this work we report the effects of hydrostatic pressure and magnetic field on the electronic transport properties of the antiferromagnetic compound Eu(3)Ir(4)Sni(3) (T-N similar to 10 K). Single crystals of Eu3Ir4Sn13 were synthesized using the Sn self-flux technique. DC electrical resistivity measurements as a function of temperature were performed by means of the four-probe technique. The high-temperature anomaly at T* similar to 57 K attributed to a structural distortion of the Sn1Sn2(12) cages in Eu3Ir4Sn13 is rapidly decreased to lower temperatures at a rate dT*/dP = 2 K/kbar, while the antiferromagnetic transition due to the Eu2+ ions is only weakly affected. Our data do not indicate any magnetoelastic effect associated with the structural instability at T*. Furthermore, the suppression of the lattice distortion by application of external pressure is not accompanied by the emergence of superconductivity, possibly due to strong magnetic correlations between the Eu2+ localized magnetic moments592International Conference on Strongly Correlated Electron Systems (SCES)2014-07FrançaUniversité Grenoble Alpe