Coupled NASTRAN/boundary element formulation for acoustic scattering

A coupled finite element/boundary element capability is described for calculating the sound pressure field scattered by an arbitrary submerged 3-D elastic structure. Structural and fluid impedances are calculated with no approximation other than discretization. The surface fluid pressures and normal velocities are first calculated by coupling a NASTRAN finite element model of the structure with a discretized form of the Helmholtz surface integral equation for the exterior field. Far field pressures are then evaluated from the surface solution using the Helmholtz exterior integral equation. The overall approach is illustrated and validated using a known analytic solution for scattering from submerged spherical shells

The exceptional Herbig Ae star HD101412: The first detection of resolved magnetically split lines and the presence of chemical spots in a Herbig star

We obtained high-resolution, high signal-to-noise UVES and a few lower quality HARPS spectra revealing the presence of resolved magnetically split lines. HD101412 is the first Herbig Ae star for which the rotational Doppler effect was found to be small in comparison to the magnetic splitting. The measured mean magnetic field modulus varies from 2.5 to 3.5kG, while the mean quadratic field was found to vary in the range of 3.5 to 4.8kG. To determine the period of variations, we used radial velocity, equivalent width, line width, and line asymmetry measurements of variable spectral lines of several elements, as well as magnetic field measurements. The most pronounced variability was detected for spectral lines of He I and the iron peak elements, whereas the spectral lines of CNO elements are only slightly variable. From spectral variations and magnetic field measurements we derived a potential rotation period P_rot=13.86d, which has to be proven in future studies with a larger number of observations. It is the first time that the presence of element spots is detected on the surface of a Herbig Ae/Be star. Our previous study of Herbig Ae stars revealed a trend towards stronger magnetic fields for younger Herbig Ae stars, confirmed by statistical tests. This is in contrast to a few other (non-statistical) studies claiming that magnetic Herbig Ae stars are progenitors of the magnetic Ap stars. New developments in MHD theory show that the measured magnetic field strengths are compatible with a current-driven instability of toroidal fields generated by differential rotation in the stellar interior. This explanation for magnetic intermediate-mass stars could be an alternative to a frozen-in fossil field.Comment: 7 pages, 6 figures, 1 table, to appear in Astronomische Nachrichte

Diffusion algebras

We define the notion of "diffusion algebras". They are quadratic Poincare-Birkhoff-Witt (PBW) algebras which are useful in order to find exact expressions for the probability distributions of stationary states appearing in one-dimensional stochastic processes with exclusion. One considers processes in which one has N species, the number of particles of each species being conserved. All diffusion algebras are obtained. The known examples already used in applications are special cases in our classification. To help the reader interested in physical problems, the cases N=3 and 4 are listed separately.Comment: 29 pages; minor misprints corrected, few references adde

The YEATS family member GAS41 interacts with the general transcription factor TFIIF

<p>Abstract</p> <p>Background</p> <p>In eukaryotes the transcription initiation by RNA polymerase II requires numerous general and regulatory factors including general transcription factors. The general transcription factor TFIIF controls the activity of the RNA polymerase II both at the initiation and elongation stages. The glioma amplified sequence 41 (GAS41) has been associated with TFIIF via its YEATS domain.</p> <p>Results</p> <p>Using GST pull-down assays, we demonstrated that GAS41 binds to both, the small subunit (RAP30) and the large subunit (RAP74) of TFIIF <it>in vitro</it>. The <it>in vivo </it>interaction of GAS41 and endogenous RAP30 and RAP74 was confirmed by co-immunoprecipitation. GAS41 binds to two non-overlapping regions of the C-terminus of RAP30. There is also an ionic component to the binding between GAS41 and RAP30. There was no evidence for a direct interaction between GAS41 and TBP or between GAS41 and RNA polymerase II.</p> <p>Conclusions</p> <p>Our results demonstrate binding between endogenous GAS41 and the endogenous TFIIF subunits (RAP30 and RAP74). Since we did not find evidence for a binding of GAS41 to TBP or RNA polymerase II, GAS41 seems to preferentially bind to TFIIF. GAS41 that does not contain a DNA-binding domain appears to be a co-factor of TFIIF.</p

Progressively excluding mammals of different body size affects community and trait structure of ground beetles

Mammalian grazing induces changes in vegetation properties in grasslands, which can affect a wide variety of other animals including many arthropods. However, the impacts may depend on the type and body size of these mammals. Furthermore, how mammals influence functional trait syndromes of arthropod communities is not well known. We progressively excluded large (e.g. red deer, chamois), medium (e.g. alpine marmot, mountain hare), and small (e.g. mice) mammals using size-selective fences in two vegetation types (short- and tall-grass vegetation) of subalpine grasslands. We then assessed how these exclusions affected the community composition and functional traits of ground beetles (Coleoptera, Carabidae), and which vegetation characteristic mediated the observed effects. Total carabid biomass, the activity densities of carabids with specific traits (i.e. small eyes, short wings), the richness of small-eyed species and the richness of herbivorous species were significantly higher when certain mammals were excluded compared to when all mammals had access, regardless of vegetation type. Excluding large and medium mammals increased the activity density of herbivorous carabid species, but only in short-grass vegetation. Similarly, excluding large mammals (ungulates) altered carabid species composition in the short-, but not in the tall-grass vegetation. All these responses were related to aboveground plant biomass, but not to plant Shannon diversity or vegetation structural heterogeneity. Our results indicate that changes in aboveground plant biomass are key drivers of mammalian grazers' influence on carabids, suggesting that bottom-up forces are important in subalpine grassland systems. The exclusion of ungulates provoked the strongest carabid response. Our results, however, also highlight the ecological significance of smaller herbivorous mammals. Our study furthermore shows that mammalian grazing not only altered carabid community composition, but also caused community-wide functional trait shifts, which could potentially have a wider impact on species interactions and ecosystem functioning

Crop Knowledge Discovery Based on Agricultural Big Data Integration

Nowadays, the agricultural data can be generated through various sources, such as: Internet of Thing (IoT), sensors, satellites, weather stations, robots, farm equipment, agricultural laboratories, farmers, government agencies and agribusinesses. The analysis of this big data enables farmers, companies and agronomists to extract high business and scientific knowledge, improving their operational processes and product quality. However, before analysing this data, different data sources need to be normalised, homogenised and integrated into a unified data representation. In this paper, we propose an agricultural data integration method using a constellation schema which is designed to be flexible enough to incorporate other datasets and big data models. We also apply some methods to extract knowledge with the view to improve crop yield; these include finding suitable quantities of soil properties, herbicides and insecticides for both increasing crop yield and protecting the environment.Comment: 5 page

Apoptosome activation, an important molecular instigator in 6-mercaptopurine induced Leydig cell death.

Leydig cells are crucial to the production of testosterone in males. It is unknown if the cancer chemotherapeutic drug, 6-mercaptopurine (6 MP), produces Leydig cell failure among adult survivors of childhood acute lymphoblastic leukemia. Moreover, it is not known whether Leydig cell failure is due to either a loss of cells or an impairment in their function. Herein, we show, in a subset of childhood cancer survivors, that Leydig cell failure is related to the dose of 6 MP. This was extended, in a murine model, to demonstrate that 6 MP exposure induced caspase 3 activation, and the loss of Leydig cells was independent of Bak and Bax activation. The death of these non-proliferating cells was triggered by 6 MP metabolism, requiring formation of both cytosolic reactive oxygen species and thiopurine nucleotide triphosphates. The thiopurine nucleotide triphosphates (with physiological amounts of dATP) uniquely activated the apoptosome. An ABC transporter (Abcc4/Mrp4) reduced the amount of thiopurines, thereby providing protection for Leydig cells. The studies reported here demonstrate that the apoptosome is uniquely activated by thiopurine nucleotides and suggest that 6 MP induced Leydig cell death is likely a cause of Leydig cell failure in some survivors of childhood cancer

The beef chain in Costa Rica: Identifying critical issues for promoting its modernization, efficiency and competitiveness

The objectives of this study were to (1) describe the economic agents of the chain and their commercial and legal relationships; (2) identify the articulations between links, technological levels, indicators of efficiency, installed capacity (scale), and degrees of occupation; (3) characterize and estimate the costing and pricing structures, and the generation of value in different links of the chain; (4) identify those critical costs that can be modified through technological interventions, policy, or other activity; (5) determine the biological and economic risk factors throughout the chain; and (6) develop a methodology to identify and estimate the costs and benefits in each segment and evaluate the generation of value throughout the beef chain. Data at the farm level was obtained from a national livestock survey (CORFOGA 2005b), which provided data on production systems, inventories, productivity, culling, and labor. In addition, surveys were carried out in different segments: (1) auction houses, (2) slaughterhouses, (3) butcher shops, and (4) supermarkets. The aim of these surveys was to describe behavior, determine risks and costs, and identify problems. The weak dynamics of livestock production in Costa Rica are reflected in unsatisfactory productivity indicators. The annual gross income was estimated as US$44/ha for cow-calf operations,$126/ha for dual purpose (including income from milk sales), and $135/ha for fattening activities. Such income rates are considered extremely low, if one uses as reference the commercial value of land allocated to livestock production (ranging between$1000 and $2000/ha). The aforementioned biological inefficiencies, combined with high land costs, impede the recovery of opportunity costs for the capital invested in land, thus making beef production uncompetitive. The cow-calf operation, with its low productivity, remunerates family labor with wages below the legal minimum. On the assumption that the only cash cost is that of labor, cow-calf farms pay family workers at a wage that is equivalent to 60$32 and $66 per animal. If the estimated unit costs are compared with the rates charged per slaughtered animal (between$15 and $23), then we have to conclude that rural slaughterhouses work at a loss and that industrial slaughterhouses cover their operational costs with processing services and the very small profit margins from sales of byproducts. The best performance in terms of efficiency and profitability is found in the retail sector of butchers and supermarkets. The rate of profits, expressed as the fraction of the final price paid by the consumer that remains in the butcher’s hands as remuneration of his work, ranges widely between 3$0.28/animal per day for the breeder and $45.85/animal per day for the butcher. Thus, the highest proportion of the total added value concentrates on the final link of the chain. The butcher or supermarket obtains, on the basis of one animal in the same unit of time, 164 times more value that the breeder located in the first link of the chain. The latter has to confront biological and economic risks not covered by insurance policies, whereas retailers may mitigate risks through insurance policies for their raw materials, equipment, and infrastructure. The competitiveness of the beef chain is the aggregate of the efficiency and productivity of all the links that form it. In a situation where, in the final segment, the demand for beef is low and weakly dynamic, then economic signs of modernization and the technological change it promotes, are not being generated in other components of the chain, particularly in the first link of production. This, in turn, results in a vicious cycle, generating low productivity and lack of competitiveness. To promote technological change, efficiency, and competitiveness in the value chain for beef in Costa Rica, we propose the following six recommendations: 1. That successful experiences of other chains such as that of poultry be analyzed and learned from to identify strategies that would increase the efficiency of the beef chain as a whole. 2. That strategies for promoting the milk production of breeding cows be developed to increase family income, as remuneration of labor is currently below the minimum wage. This option would be viable only in localities where a milk market exists. That livestock producer funds [a livestock producer fund consists of granting livestock in company to produce meat, provided that the producer concerned has adequate pastures for this purpose on his farm] be created as mechanisms to develop social capital, reduce transaction costs, and help improve the chain’s productivity and profitability. These organizations would bring together the different classes of the chain and favor synergies in the interaction of public and private actors. 3. That incentives be created to promote the large-scale adoption of already available improved forage species, as most of the problem of low livestock productivity originates in poor and deficient feed. This strategy would emphasize feeding during dry seasons, thereby minimizing seasonal weight losses in the national herd and improving the profitability of farms. 4. That a carcass classification system be established, based on quality and price that would permit differentiating supplies for different segments of the market. 5. That consumer education be promoted on the health benefits of beef, forms of preparation, and differentiating between cuts, uses, and qualities of beef products