1,485 research outputs found
Multiexciton molecules in the hexaborides
We investigate multiexciton bound states in a semiconducting phase of
divalent hexaborides. Due to three degenerate valleys in both the conduction
and valence bands the binding energy of a 6-exciton molecule is greatly
enhanced by the shell effect. The ground state energies of multiexciton
molecules are calculated using the density functional formalism. We also show
that charged impurities stabilize multiexciton complexes leading to
condensation of localized excitons. These complexes can act as nucleation
centers of local moments.Comment: RevTEX, 7 pages with 3 figure
An accurate density functional theory for the vapor-liquid interface of associating chain molecules based on the statistical associating fluid theory for potentials of variable range.
Published versio
In-situ measurements of oxygen, carbon monoxide and greenhouse gases from Ochsenkopf tall tower in Germany
We present 2.5 years (from June 2006 to December 2008) of in-situ measurements of CO2, O2, CH4, CO, N2O and SF6 mixing ratios sampled from 23, 90 and 163m above ground on the Ochsenkopf tower in the Fichtelgebirge range, Germany (50?0104900 N, 11?4803000 E, 1022ma.s.l.). In addition to the in-situ measurements, flask samples are taken at Ochsenkopf at approximately weekly intervals and are subsequently analysed for the mixing ratios of the same species, as well as H2, and the stable isotopes, ?13C, ?18O in CO2. The in-situ measurements of CO2 and O2 from 23m show substantial diurnal variations that are modulated by biospheric fluxes, combustion of fossil fuels, and by diurnal changes in the planetary boundary layer height. Measurements from 163m exhibit only very weak diurnal variability, as this height (1185ma.s.l.) is generally above the nocturnal boundary layer. CH4, CO, N2O and SF6 show little diurnal variation even at 23m owing to the absence of any significant diurnal change in the fluxes and the absence of any strong local sources or sinks. From the in-situ record, the seasonal cycles of the gas species have been characterized and the multi-annual trends determined. Because the record is short, the calculation of the trend is sensitive to inter-annual variations in the amplitudes of the seasonal cycles. However, for CH4 a significant change in the growth-rate was detected for 2006.5â2008.5 as compared with the global mean from 1999 to 2006 and is consistent with other recent observations of a renewed increasing global growth rate in CH4 since the beginning of 2007
Results from the tall tower measurement station for atmospheric greenhouse gases at BiaĹystok, Poland
Operationalization and reliability testing of ICF categories relevant for physiotherapists' interventions in the acute hospital
Objective: To operationalize items based on categories of
the International Classification of Functioning, Disability
and Health (ICF) relevant to patient problems that are addressed by physiotherapeutic interventions in the acute hospital, and to test the reliability of these items when applied by physiotherapists.
Methods: A selection of 124 ICF categories was operationalized in a formal decision-making and consensus process. The reliability of the newly operationalized item list was tested with a cross-sectional study with repeated measurements.
Results: The item writing process resulted in 94 dichotomous
and 30 polytomous items. Data were collected in a convenience sample of 28 patients with neurological, musculoskeletal, cardiopulmonary, or internal organ conditions, requiring physical therapy in an acute hospital. Fifty-six percent of the polytomous and 68% of the dichotomous items had a raw agreement of 0.7 or above, whereas 36% of all polytomous and 34% of all dichotomous items had a kappa coefficient of 0.7 and above.
Conclusion: The study supports that the ICF is adaptable to
professional and setting-specific needs of physiotherapists.
Further research towards the development of reliable instruments for physiotherapists based on the ICF seems justified.
Key words: ICF; classification; reliability; outcome measures; health status assessment
Effect of agroclimatic variability on land suitability for cultivating rubber (Hevea brasiliensis) and growth performance assessment in the tropical rainforest climate of Peninsular Malaysia
Climate change directly alters climate conditions and indirectly impacts land suitability for cultivating rubber. The Malaysian tropical rainforest climate with regular rainfall of about 2000â2500 mm per year and the average temperature of 26â28 °C provide a suitable condition for planting rubber commercially. There is doubt about how well rubber plants will perform in the future because of climate change. The main question of whether rubber is still appropriate for planting in Peninsular Malaysia must be answered conclusively as rubber requires an approximately 30 year investment in one cycle. This question is particularly relevant in Malaysia as its rubber production is dependent on smallholders. Smallholders contribute approximately 93% of natural rubber production and furthermore, 93% of the rubber land area in Malaysia is owned by smallholders. An agroclimatic map produced in this study will help smallholders in deciding whether to proceed with rubber or change to other valuable crops based on their specific location. In this study, we evaluate 21st century land suitability for cultivating rubber and assess its growth based on climatic data for the Historical (1970â2000), Early (2010â2040), Middle (2040â2070) and End (2070â2100) projections periods. We use the Hevea 1.0 static model for rubber tree modelling to calculate the agroclimatic indices and estimate 30 yearsâ of actual rubber growth (girth) for all study periods. We find that climate change is predicted to have a positive impact on rubber-suitability in tropical rainforest in Malaysia climates at least until 2100. The End period, where the precipitation and temperature are projected to experience significant increases, becomes more favourable to rubber. The Perak region shows the highest increase in estimated rubber growth in the Early, Middle, and End periods by 16.3%, 31.9% and 39.4%, respectively. Among all regions, Kelang is predicted to be the most suitable area to plant rubber during the Early period as it has a potential estimated girth of up to 94.5 cm. Meanwhile, Johor is predicted to be the best place to cultivate rubber during the Middle and End periods with growth estimations of 97 cm and 99.5 cm, respectively. We indicate that about 32% of existing planted rubber area in Peninsular Malaysia is in Class 6 of land suitability to cultivate rubber
Can We Detect Changes in Amazon Forest Structure Using Measurements of the Isotopic Composition of Precipitation?
Largeâscale (>500 km) spatial gradients of precipitation oxygen isotopeâratios (δ18Op) hold information about the hydrological cycle. They result from the interplay between rainout and evapotranspiration along airâparcel paths, but these counteracting effects are difficult to disentangle complicating quantification of the effect of land cover change on δ18Op. We show that disentangling can qualitatively be achieved using climate model simulations with a landâderived precipitation tracer for tropical South America. We then either vary land cover as observed since 1870 or by replacing Amazon forests with bare land to determine the resulting signals. Our results indicate that effects of historically changing land cover on annual mean δ18O isotopeâratio gradients are small and unlikely detectable, although there is a noticeable signal during the dry season. Furthermore, the effect of changes in water recycling on Amazon δ18Op in paleoârecords may have been overestimated and need reinterpretation
Roux-en-Y Drainage of the Pancreatic Stump Decreases Pancreatic Fistula After Distal Pancreatic Resection
Clinically relevant fistula after distal pancreatic resection occurs in 5-30% of patients, prolonging recovery and considerably increasing in-hospital stay and costs. We tested whether routine drainage of the pancreatic stump into a Roux-en-Y limb after distal pancreatic resection decreased the incidence of fistula. From October 2001, data of all patients undergoing pancreatic distal resection were entered in a prospective database. From June 2003 after resection, the main pancreatic duct and the pancreatic stump were oversewn, and in addition, anastomosed into a jejunal Roux-en-Y limb by a single-layer suture (nâ=â23). A drain was placed near the anastomosis, and all patients received octreotide for 5-7days postoperatively. The volume of the drained fluid was registered daily, and concentration of amylase was measured and recorded every other day. Patient demographics, hospital stay, pancreatic fistula incidence (âĽ30ml amylase-rich fluid/day on/after postoperative day 10), perioperative morbidity, and follow-up after discharge were compared with our initial series of patients (treated October 2001-May 2003) who underwent oversewing only (nâ=â20). Indications, patient demographics, blood loss, and tolerance of an oral diet were similar. There were four (20%) pancreatic fistulas in the "oversewnâ group and none in the anastomosis group (pâ<â0.05). Nonsurgical morbidity, in-hospital stay, and follow-up were comparable in both group
Regional Mapping and Spatial Distribution Analysis of Canopy Palms in an Amazon Forest Using Deep Learning and VHR Images
Mapping plant species at the regional scale to provide information for ecologists and forest managers is a challenge for the remote sensing community. Here, we use a deep learning algorithm called U-net and very high-resolution multispectral images (0.5 m) from GeoEye satellite to identify, segment and map canopy palms over âź3000 km2 of Amazonian forest. The map was used to analyse the spatial distribution of canopy palm trees and its relation to human disturbance and edaphic conditions. The overall accuracy of the map was 95.5% and the F1-score was 0.7. Canopy palm trees covered 6.4% of the forest canopy and were distributed in more than two million patches that can represent one or more individuals. The density of canopy palms is affected by human disturbance. The post-disturbance density in secondary forests seems to be related to the type of disturbance, being higher in abandoned pasture areas and lower in forests that have been cut once and abandoned. Additionally, analysis of palm treesâ distribution shows that their abundance is controlled naturally by local soil water content, avoiding both flooded and waterlogged areas near rivers and dry areas on the top of the hills. They show two preferential habitats, in the low elevation above the large rivers, and in the slope directly below the hill tops. Overall, their distribution over the region indicates a relatively pristine landscape, albeit within a forest that is critically endangered because of its location between two deforestation fronts and because of illegal cutting. New tree species distribution data, such as the map of all adult canopy palms produced in this work, are urgently needed to support Amazon species inventory and to understand their distribution and diversity
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