Contribution of the nucleon-hyperon reaction channels to K−^- production in proton-nucleus collisions

The cross sections for producing K$^-$ mesons in nucleon-hyperon elementary processes are estimated assuming one-pion exchange and using the experimentally known pion-hyperon cross sections. The results are implemented in a transport model which is applied to calculation of proton-nucleus collisions. In significant difference to earlier estimates for heavy-ion collisions the inclusion of the nucleon-hyperon cross section roughly doubles the K$^-$ production in near-threshold proton-nucleus collisions

Avaliação da avifauna em sistemas agroflorestais com dendê (Elaeis guianeensis) no município de Tomé-Açu (PA).

È apresentada uma comparação entre a composição da avifauna de sistemas agroflorestais (SAF) com dendê, copoeiras e uma monocultura de dendê ao longo de dois anos no intuito de relatar a funcionalidade dos SAFs na manutenção de aves amazônicas. Foram registradas 196 espécies, destas 88 encontradas nos SAFs, 120 na capoeira e 63 na monocultura. Foi observada a ausência de espécies florestais das famílias, Thamnophilidae, Furnaridae e Tyrannidae no SAF e na monocultura de dendê, presentes na capoeira. O índice de similaridade de Morisita mostra que os SAFs se assemelham mais às monoculturas do que às capoeiras, possivelmente devido ao tempo recente de plantio, onde os SAFs ainda não apresentam uma estrutura florestal mais complexa com sub-bosque e dossel. Foi observado um aumento na riqueza de espécies frutívoras e nectarívoras e na diversidade dos SAFs, possivelmente refletindo o contínuo desenvolvimento e estruturação deste sistema. Os resultados apresentados mostram que apesar de os SAFs apresentarem uma comunidade de aves em geral distinta da comunidade encontrada nas capoeiras, estas apresentam índices de diversidade e riqueza de espécies semelhantes. A monocultura de dendê apresentou a menor riqueza e índices de diversidade, além de apresentar principalmente espécies insetívoras, onívoras e granívoras na composição de sua avifauna, configurando um ambiente pouco diverso na estrutura da vegetação. Sistemas agroflorestais de dendê podem vir a contribuir na manutenção da diversidade local de aves florestais amazônicas, contudo os resultados apontam a necessidade de mais tempo para um melhor desenvolvimento do sistema.Editores técnicos: Roberto Porro, Milton Kanashiro, Maria do Socorro Gonçalves Ferreira, Leila Sobral Sampaio e Gladys Ferreira de Sousa

Cross-Field Plasma Acceleration and Potential Formation Induced by Electromagnetic Waves in a Relativistic Magnetized Plasma

Abstract It has been proved theoretically that particle acceleration along and across a magnetic field and electric field across a magnetic field can be induced by nonlinear Landau damping of almost perpendicularly propagating electrostatic waves in a relativistic magnetized plasma

Measuring Temperature Gradients over Nanometer Length Scales

When a quantum dot is subjected to a thermal gradient, the temperature of electrons entering the dot can be determined from the dot's thermocurrent if the conductance spectrum and background temperature are known. We demonstrate this technique by measuring the temperature difference across a 15 nm quantum dot embedded in a nanowire. This technique can be used when the dot's energy states are separated by many kT and will enable future quantitative investigations of electron-phonon interaction, nonlinear thermoelectric effects, and the effciency of thermoelectric energy conversion in quantum dots.Comment: 6 pages, 5 figure

Target mass number dependence of subthreshold antiproton production in proton-, deuteron- and alpha-particle-induced reactions

Data from KEK on subthreshold \bar{\mrm{p}} as well as on $\pi^\pm$ and \mrm{K}^\pm production in proton-, deuteron- and $\alpha$-induced reactions at energies between 2.0 and 12.0 A GeV for C, Cu and Pb targets are described within a unified approach. We use a model which considers a nuclear reaction as an incoherent sum over collisions of varying numbers of projectile and target nucleons. It samples complete events and thus allows for the simultaneous consideration of all final particles including the decay products of the nuclear residues. The enormous enhancement of the \bar{\mrm{p}} cross section, as well as the moderate increase of meson production in deuteron and $\alpha$ induced compared to proton-induced reactions, is well reproduced for all target nuclei. In our approach, the observed enhancement near the production threshold is mainly due to the contributions from the interactions of few-nucleon clusters by simultaneously considering fragmentation processes of the nuclear residues. The ability of the model to reproduce the target mass dependence may be considered as a further proof of the validity of the cluster concept.Comment: 9 pages, 4 figure

Bone marrow mesenchymal stem cells do not enhance intra-synovial tendon healing despite engraftment and homing to niches within the synovium

Intra-synovial tendon injuries display poor healing, which often results in reduced functionality and pain. A lack of effective therapeutic options has led to experimental approaches to augment natural tendon repair with autologous mesenchymal stem cells (MSCs) although the effects of the intra-synovial environment on the distribution, engraftment and functionality of implanted MSCs is not known. This study utilised a novel sheep model which, although in an anatomically different location, more accurately mimics the mechanical and synovial environment of the human rotator cuff, to determine the effects of intra-synovial implantation of MSCs

Characterization facility for magneto-optic media and systems

Objectives of this research are: (1) to measure the hysteresis loop, Kerr rotation angle, anisotropy energy profile, Hall voltage, and magnetoresistance of thin-film magneto-optic media using our loop-tracer; (2) measure the wavelength-dependence of the Kerr rotation angle, Theta(sub k), and ellipticity, epsilon(sub k), for thin-film media using our magneto-optic Kerr spectrometer (MOKS); (3) measure the dielectric tensor of thin-film and multilayer samples using our variable-angle magneto-optic ellipsometer (VAMOE); (4) measure the hysteresis loop, coercivity, remanent magnetization, saturation magnetization, and anisotropy energy constant for thin film magnetic media using vibrating sample magnetometry; (5) observe small magnetic domains and investigate their interaction with defects using magnetic force microscopy; (6) perform static read/write/erase experiments on thin-film magneto-optic media using our static test station; (7) integrate the existing models of magnetization, magneto-optic effects, coercivity, and anisotropy in an interactive and user-friendly environment, and analyze the characterization data obtained in the various experiments, using this modeling package; (8) measure focusing- and tracking-error signals on a static testbed, determine the 'feedthrough' for various focusing schemes, investigate the effects of polarization and birefringence, and compare the results with diffraction-based calculations; and (9) measure the birefringence of optical disk substrates using two variable angle ellipsometers

First Dark Matter Limits from a Large-Mass, Low-Background Superheated Droplet Detector

We report on the fabrication aspects and calibration of the first large active mass ($\sim15$ g) modules of SIMPLE, a search for particle dark matter using Superheated Droplet Detectors (SDDs). While still limited by the statistical uncertainty of the small data sample on hand, the first weeks of operation in the new underground laboratory of Rustrel-Pays d'Apt already provide a sensitivity to axially-coupled Weakly Interacting Massive Particles (WIMPs) competitive with leading experiments, confirming SDDs as a convenient, low-cost alternative for WIMP detection.Comment: Final version, Phys. Rev. Lett. (in press

Espécies adubadeiras como fonte de nutrientes para o cultivo de dendê (Elaeis guineensis) em sistemas agroflorestais, Tomé Açu (PA).

Este trabalho tem como objetivo estudar as espécies adubadeiras utilizadas como fonte de nutrientes para o cultivo de dendê (Elaeis guineensis) em sistemas agroflorestais, em Tomé Açu (PA)

Identification of a novel biomarker candidate, a 4.8-kDa peptide fragment from a neurosecretory protein VGF precursor, by proteomic analysis of cerebrospinal fluid from children with acute encephalopathy using SELDI-TOF-MS

<p>Abstract</p> <p>Background</p> <p>Acute encephalopathy includes rapid deterioration and has a poor prognosis. Early intervention is essential to prevent progression of the disease and subsequent neurologic complications. However, in the acute period, true encephalopathy cannot easily be differentiated from febrile seizures, especially febrile seizures of the complex type. Thus, an early diagnostic marker has been sought in order to enable early intervention. The purpose of this study was to identify a novel marker candidate protein differentially expressed in the cerebrospinal fluid (CSF) of children with encephalopathy using proteomic analysis.</p> <p>Methods</p> <p>For detection of biomarkers, CSF samples were obtained from 13 children with acute encephalopathy and 42 children with febrile seizure. Mass spectral data were generated by surface-enhanced laser desorption/ionization time-of-flight mass spectrometry (SELDI-TOF MS) technology, which is currently applied in many fields of biological and medical sciences. Diagnosis was made by at least two pediatric neurologists based on the clinical findings and routine examinations. All specimens were collected for diagnostic tests and the remaining portion of the specimens were used for the SELDI-TOF MS investigations.</p> <p>Results</p> <p>In experiment 1, CSF from patients with febrile seizures (n = 28), patients with encephalopathy (n = 8) (including influenza encephalopathy (n = 3), encephalopathy due to rotavirus (n = 1), human herpes virus 6 (n = 1)) were used for the SELDI analysis. In experiment 2, SELDI analysis was performed on CSF from a second set of febrile seizure patients (n = 14) and encephalopathy patients (n = 5). We found that the peak with an m/z of 4810 contributed the most to the separation of the two groups. After purification and identification of the 4.8-kDa protein, a 4.8-kDa proteolytic peptide fragment from the neurosecretory protein VGF precursor (VGF4.8) was identified as a novel biomarker for encephalopathy.</p> <p>Conclusions</p> <p>Expression of VGF4.8 has been reported to be decreased in pathologically degenerative changes such as Alzheimer's disease, amyotrophic lateral sclerosis (ALS), frontotemporal dementia, and encephalopathy. Thus, the VGF4.8 peptide might be a novel marker for degenerative brain conditions.</p