Vector mesons in a relativistic point-form approach

We apply the point form of relativistic quantum mechanics to develop a Poincare invariant coupled-channel formalism for two-particle systems interacting via one-particle exchange. This approach takes the exchange particle explicitly into account and leads to a generalized eigenvalue equation for the Bakamjian-Thomas type mass operator of the system. The coupling of the exchange particle is derived from quantum field theory. As an illustrative example we consider vector mesons within the chiral constituent quark model in which the hyperfine interaction between the confined quark-antiquark pair is generated by Goldstone-boson exchange. We study the effect of retardation in the Goldstone-boson exchange by comparing with the commonly used instantaneous approximation. As a nice physical feature we find that the problem of a too large $\rho$-$\omega$ splitting can nearly be avoided by taking the dynamics of the exchange meson explicitly into account.Comment: 14 pages, 1 figur

The impact of land cover change on surface energy and water balance in Mato Grosso, Brazil

The sensitivity of surface energy and water fluxes to recent land cover changes is simulated for a small region in northern Mato Grosso, Brazil. The Simple Biosphere Model (SiB2) is used, driven by biophysical parameters derived from the Moderate Resolution Imaging Spectroradiometer (MODIS) at 250-m resolution, to compare the effects of different land conversion types. The mechanisms through which changes in vegetation alter surface fluxes of energy, momentum, water, and carbon are analyzed for both wet and dry seasons. It is found that morphological changes contribute to warming and drying of the atmosphere while physiological changes, particularly those associated with a plant’s photosynthetic pathway, counterbalance or exacerbate the warming depending on the type of conversion and the season. Furthermore, this study’s results indicate that initial clearing of evergreen and transition forest to bare ground increases canopy temperature by up to 1.7°C. For subsequent land use such as pasture or cropland, the largest effect is seen for the conversion of evergreen forest to C3 cropland during the wet season, with a 21% decrease of the latent heat flux and 0.4°C increase in canopy temperature. The secondary conversion of pasture to cropland resulted in slight warming and drying during the wet season driven mostly by the change in carbon pathway from C4 to C3. For all conversions types, the daily temperature range is amplified, suggesting that plants replacing forest clearing require more temperature tolerance than the trees they replace. The results illustrate that the effect of deforestation on climate depends not only on the overall extent of clearing but also on the subsequent land use type

Stimulus - response curves of a neuronal model for noisy subthreshold oscillations and related spike generation

We investigate the stimulus-dependent tuning properties of a noisy ionic conductance model for intrinsic subthreshold oscillations in membrane potential and associated spike generation. On depolarization by an applied current, the model exhibits subthreshold oscillatory activity with occasional spike generation when oscillations reach the spike threshold. We consider how the amount of applied current, the noise intensity, variation of maximum conductance values and scaling to different temperature ranges alter the responses of the model with respect to voltage traces, interspike intervals and their statistics and the mean spike frequency curves. We demonstrate that subthreshold oscillatory neurons in the presence of noise can sensitively and also selectively be tuned by stimulus-dependent variation of model parameters.Comment: 19 pages, 7 figure

A new approach to sensitivity climatologies: the DTS-MEDEX-2009 campaign

Adaptive observation is an approach to improving the quality of numerical weather forecasts through the optimization of observing networks. It is sometimes referred to as Data Targeting (DT). This approach has been applied to high impact weather during specific field campaigns in the past decade. Adaptive observations may involve various types of observations, including either specific research observing platforms or routine observing platforms employed in an adaptive way. The North-Atlantic TReC 2003 and the EURORISK-PREVIEW 2008 exercises focused on the North-Atlantic and Western Europe areas using mainly routine observing systems. These campaigns also included Mediterranean cases. <br><br> The most recent campaign, DTS-MEDEX-2009, is the first campaign in which the DT method has been used to address exclusively Mediterranean high impact weather events. In this campaign, which is an important stage in the MEDEX development, only operational radiosonde stations and commercial aircraft data (AMDAR) have provided additional observations. Although specific diagnostic studies are needed to assess the impact of the extra-observations on forecast skill and demonstrate the effectiveness of DTS-MEDEX-2009, some preliminary findings can be deduced from a survey of this targeting exercise. <br><br> After a description of the data targeting system and some illustrations of particular cases, this paper attempts some comparisons of additional observation needs (through effectively deployed radio-soundings) with sensitivity climatologies in the Mediterranean. The first step towards a sensitivity climatology for Mediterranean cases of high impact weather is indirectly given by the frequency of extra-soundings launched from the network of radiosonde stations involved in the DTS-MEDEX-2009 campaign

Land-use in Amazonia and the cerrado of Brazil.

The total area and annual rate of native vegetation clearing is greatest in the Cerrado region followed by the Brazilian states of Para, Mato Grosso, Maranhao and Rondonia. Amazonian forest clearing proceeds most quickly where abundant natural resources (wood or land) are accessible by roads and close to markets. These regions are concentrated along the eastern and southern flanks of Amazonia, particularly in eastern Para, Cuiaba and Rondonia. There are still large discrepancies in estimates of annual deforestation; Landsat (Thematic Mapper-based) mapping of deforestation in the closed-canopy forests of Amazonia has not include non-Brazilian countries and is incomplete for the cerrado biome. Amazonian deforestation was last mapped 1994. Current estimates of Amazonian forest clearing do not include most of the forests that are affected by logging each year, which is an area (about 7,000 km2 yr-1)more than half the size of the area of annual deforestation. Logging changes forest structure and increases forest flammability. The intensity of logging ranges from 1-to 100-species harvest, and averages 20m3 of wood harvested per hectare. Logging may increase dramatically in the coming years. Fire affects large, but difficult to measure, areas of pastureland, logged forests, secondary forests and primary forests. Forest ground fires are particularly difficult to map fom satellite data. Fire is more frequent where forest clearing is taking place, and where seasonal drought is most severe. The destiny of Amazonian forest land cleared for crops and cattle pasture is complex, and highly variables regionally. Areal estimates are needed for managed pasture, degraded pasture, cropland and secondadry forests, for these ecosystems are functionally distinct. Most forest clearing is for pasture establishment, followed by shifting cultivation. Cattle pasture is the logical land-use for both small-scale and large-scale rural Amazonians because cattle are easily sold or traded, and they maintain their value during inflation. Cattle patures help secure land claims and increase land value. In the Cerrado, there has been a shift from extensive cattle grazing of natural savannas to pasture planted with African forage grasses; mechanized soy bean production is the second most extensive land-use. Pastures are the most important land-cover for the LBA (Large-Scale Biosphere - Atmosphere experiment in Amazonia) science campaign. Brazilian Amazonia experiences reduced rainfall during ENSO events. ENSO-related drought is most severe in eastern Amazonia. A basin-wide reduction in rainfall would have its greatest affect on vegetation near the border between savanna and closed-canopy forest in Rondonia, Mato Grosso, Para and Tocantins. The LBA campaign should be conducted in variety of rural landscapes to capture the multiplicity of human effects on native ecosystems, as well as the range of cliamatic and edaphic conditions under which these ecosystems have evolved. It should address the current (ENSO) and predicted variations in climate, and should be designed to recommend those land-uses that best reconcile the maintenance of ecosystem processes with socially equitable economic growth

Point-Form Analysis of Elastic Deuteron Form Factors

Point-form relativistic quantum mechanics is applied to elastic electron-deuteron scattering. The deuteron is modeled using relativistic interactions that are scattering-equivalent to the nonrelativistic Argonne $v_{18}$ and Reid '93 interactions. A point-form spectator approximation (PFSA) is introduced to define a conserved covariant current in terms of single-nucleon form factors. The PFSA is shown to provide an accurate description of data up to momentum transfers of 0.5 ${\rm GeV}^2$, but falls below the data at higher momentum transfers. Results are sensitive to the nucleon form factor parameterization chosen, particularly to the neutron electric form factor.Comment: RevTex, 31 pages, 1 table, 13 figure

What drives sound symbolism? Different acoustic cues underlie sound-size and sound-shape mappings

Sound symbolism refers to the non-arbitrary mappings that exist between phonetic properties of speech sounds and their meaning. Despite there being an extensive literature on the topic, the acoustic features and psychological mechanisms that give rise to sound symbolism are not, as yet, altogether clear. The present study was designed to investigate whether different sets of acoustic cues predict size and shape symbolism, respectively. In two experiments, participants judged whether a given consonant-vowel speech sound was large or small, round or angular, using a size or shape scale. Visual size judgments were predicted by vowel formant F1 in combination with F2, and by vowel duration. Visual shape judgments were, however, predicted by formants F2 and F3. Size and shape symbolism were thus not induced by a common mechanism, but rather were distinctly affected by acoustic properties of speech sounds. These findings portray sound symbolism as a process that is not based merely on broad categorical contrasts, such as round/unround and front/back vowels. Rather, individuals seem to base their sound-symbolic judgments on specific sets of acoustic cues, extracted from speech sounds, which vary across judgment dimensions

Effect of a multidisciplinary stress treatment programme on the return to work rate for persons with work-related stress. A non-randomized controlled study from a stress clinic

<p>Abstract</p> <p>Background</p> <p>In recent years an increasing number of patients have been referred to the medical sector with stress symptoms. Moreover, these conditions imply increased sickness absence. This indicates a need for treatment programmes in general medical practice. The aim of this study was to test the effect of a multidisciplinary stress treatment programme on the return to work (RTW) rate in persons with work-related stress and establish predictive factors for this outcome.</p> <p>Methods</p> <p>During a two-year period 63 out of 73 referrals to the Stress Clinic (a section of a Clinic of Occupational Medicine) completed a stress treatment programme consisted of the following:</p> <p>1) Identification of relevant stressors. 2. Changing the coping strategies of the participants. 3. Evaluating/changes in participant workload and tasks. 4. Relaxation techniques. 5. Physical exercise. 6. Psychiatric evaluation when indicated by depression test score.</p> <p>On average each patient attended six one-hour sessions over the course of four months.</p> <p>A group of 34 employees referred to the Clinic of Occupational Medicine by their general practitioners served as a control group. Each participant had a one-hour consultation at baseline and after four months. A specialist in occupational medicine carried out all sessions.</p> <p>Return To Work (RTW), defined as having a job and not being on sick leave at the census, was used as outcome measure four months after baseline, and after one and two years.</p> <p>Results</p> <p>The level of sick leave in the stress treatment group dropped from 52% to 16% during the first four months of follow-up and remained stable. In the control group, the reduction in sick leave was significantly smaller, ranging from 48% at baseline to 27% after four months and 24% after one year. No statistically significant difference between the two groups was observed after one and two years. Age below 50 years and being a manager increased the odds ratio for RTW after one and two years, while gender and depression had no predictive value.</p> <p>Conclusions</p> <p>The stress treatment programme showed a significant effect on the return to work rate. The stress treatment programme seems feasible for general practitioners.</p> <p>Trial Registration</p> <p>ISRCTN04354658</p

Analysis of Gene expression in soybean (Glycine max) roots in response to the root knot nematode Meloidogyne incognita using microarrays and KEGG pathways

<p>Abstract</p> <p>Background</p> <p>Root-knot nematodes are sedentary endoparasites that can infect more than 3000 plant species. Root-knot nematodes cause an estimated $100 billion annual loss worldwide. For successful establishment of the root-knot nematode in its host plant, it causes dramatic morphological and physiological changes in plant cells. The expression of some plant genes is altered by the nematode as it establishes its feeding site.</p> <p>Results</p> <p>We examined the expression of soybean (<it>Glycine max</it>) genes in galls formed in roots by the root-knot nematode, <it>Meloidogyne incognita</it>, 12 days and 10 weeks after infection to understand the effects of infection of roots by <it>M. incognita</it>. Gene expression was monitored using the Affymetrix Soybean GeneChip containing 37,500 <it>G. max </it>probe sets. Gene expression patterns were integrated with biochemical pathways from the Kyoto Encyclopedia of Genes and Genomes using PAICE software. Genes encoding enzymes involved in carbohydrate and cell wall metabolism, cell cycle control and plant defense were altered.</p> <p>Conclusions</p> <p>A number of different soybean genes were identified that were differentially expressed which provided insights into the interaction between <it>M. incognita </it>and soybean and into the formation and maintenance of giant cells. Some of these genes may be candidates for broadening plants resistance to root-knot nematode through over-expression or silencing and require further examination.</p