Climate change impacts on snow water availability in the Euphrates-Tigris basin

This study investigates the effects of projected climate change on snow water availability in the Euphrates-Tigris basin using the Variable Infiltration Capacity (VIC) macro scale hydrologic model and a set of regional climate-change outputs from 13 global circulation models (GCMs) forced with two greenhouse gas emission scenarios for two time periods in the 21st century (2050 and 2090). The hydrologic model produces a reasonable simulation of seasonal and spatial variation in snow cover and associated snow water equivalent (SWE) in the mountainous areas of the basin, although its performance is poorer at marginal snow cover sites. While there is great variation across GCM outputs influencing snow water availability, the majority of models and scenarios suggest a significant decline (between 10 and 60 percent) in available snow water, particularly under the high-impact A2 climate change scenario and later in the 21st century. The changes in SWE are more stable when multi-model ensemble GCM outputs are used to minimize inter-model variability, suggesting a consistent and significant decrease in snow-covered areas and associated water availability in the headwaters of the Euphrates-Tigris basin. Detailed analysis of future climatic conditions point to the combined effects of reduced precipitation and increased temperatures as primary drivers of reduced snowpack. Results also indicate a more rapid decline in snow cover in the lower elevation zones than the higher areas in a changing climate but these findings also contain a larger uncertainty. The simulated changes in snow water availability have important implications for the future of water resources and associated hydropower generation and land-use management and planning in a region already ripe for interstate water conflict. While the changes in the frequency and intensity of snow-bearing circulation systems or the interannual variability related to climate were not considered, the simulated changes in snow water availability presented here are likely to be indicative of climate change impacts on the water resources of the Euphrates-Tigris basin

Search for spin gapless semiconductors: The case of inverse Heusler compounds

We employ ab-initio electronic structure calculations to search for spin gapless semiconductors, a recently identified new class of materials, among the inverse Heusler compounds. The occurrence of this property is not accompanied by a general rule and results are materials specific. The six compounds identified show semiconducting behavior concerning the spin-down band structure and in the spin-up band structure the valence and conduction bands touch each other leading to 100% spin-polarized carriers. Moreover these six compounds should exhibit also high Curie temperatures and thus are suitable for spintronics applications.Comment: Submitted to Applied Physics Letter

Effects of oregano essential oil and capsicum extract on fattening, serum constituents, and rumen fermentation of lambs

This study investigated dietary supplementation of weaned lambs with Origanum vulgare essential oil and Capsicum oleoresin (chilli pepper) extract. Thirty-six eight-week-old male and female Menemen lambs were used in this study. Three dietary treatment groups consisted of T1, an unsupplemented control group; T2, a group supplemented with 300 mg/kg oregano essential oil, and T3, a group supplemented with 300 mg/kg Capsicum oleoresin. Feed and fresh water were available to the lambs ad libitum during the 56-day experiment. No significant effects of treatment were detected on growth rate, feed intake and feed conversion. In addition, serum urea, creatine, total protein, albumin, amylase, aspartate amino transferase (AST), alanine amino transferase (ALT), and gamma glutamyl transferase (GGT) levels did not differ among treatments on day 56 of the study. When oregano oil and capsicum extract were added to the feed, total volatile fatty acids (TVFA), acetate (AA), propionate (PA), butyrate (BA), isobutyrate (IBA), valerate (VA), and AA to PA ratio in the rumen were decreased significantly in comparison with the control group at two hours after feeding, with the effect of T2 being greater than that of T3. Female lambs had lower levels of TVFA than male lambs. Thus, although neither additive affected fattening performance and serum constituents of the lambs, both altered the rumen fatty acid profile

Structural stability and energetics of single-walled carbon nanotubes under uniaxial strain

A (10x10) single-walled carbon nanotube consisting of 400 atoms with 20 layers is simulated under tensile loading using our developed O(N) parallel tight-binding molecular-dynamics algorithms. It is observed that the simulated carbon nanotube is able to carry the strain up to 122% of the relaxed tube length in elongation and up to 93% for compression. Young s modulus, tensile strength, and the Poisson ratio are calculated and the values found are 0.311 TPa, 4.92 GPa, and 0.287, respectively. The stress-strain curve is obtained. The elastic limit is observed at a strain rate of 0.09 while the breaking point is at 0.23. The frequency of vibration for the pristine (10x10) carbon nanotube in the radial direction is 4.71x10^3 GHz and it is sensitive to the strain rate.Comment: 11 pages, 8 figure

Thermal Stability of Metallic Single-Walled Carbon Nanotubes: An O(N) Tight-Binding Molecular Dynamics Simulation Study

Order(N) Tight-Binding Molecular Dynamics (TBMD) simulations are performed to investigate the thermal stability of (10,10) metallic Single-Walled Carbon Nanotubes (SWCNT). Periodic boundary conditions (PBC) are applied in axial direction. Velocity Verlet algorithm along with the canonical ensemble molecular dynamics (NVT) is used to simulate the tubes at the targeted temperatures. The effects of slow and rapid temperature increases on the physical characteristics, structural stability and the energetics of the tube are investigated and compared. Simulations are carried out starting from room temperature and the temperature is raised in steps of 300K. Stability of the simulated metallic SWCNT is examined at each step before it is heated to higher temperatures. First indication of structural deformation is observed at 600K. For higher heat treatments the deformations are more pronounced and the bond breaking temperature is reached around 2500K. Gradual (slow) heating and thermal equilibrium (fast heating) methods give the value of radial thermal expansion coefficient in the temperature range between 300K-600K as 0.31x10^{-5}(1/K) and 0.089x10^{-5}(1/K), respectively. After 600K, both methods give the same value of 0.089x10^{-5}(1/K). The ratio of the total energy per atom with respect to temperature is found to be 3x10^{-4} eV/K

Functionalizing graphene by embedded boron clusters

We present a model system that might serve as a blueprint for the controlled layout of graphene based nanodevices. The systems consists of chains of B7 clusters implanted in a graphene matrix, where the boron clusters are not directly connected. We show that the graphene matrix easily accepts these alternating boron chains, and that the implanted boron components may dramatically modify the electronic properties of graphene based nanomaterials. This suggests a functionalization of graphene nanomaterials, where the semiconducting properties might be supplemented by parts of the graphene matrix itself, but the basic wiring will be provided by alternating chains of implanted boron clusters that connect these areas.Comment: 10 pages, 2 figures, 1 tabl

O(N) algorithms in tight-binding molecular-dynamics simulations of the electronic structure of carbon nanotubes

The O(N) and parallelization techniques have been successfully applied in tight-binding molecular-dynamics simulations of single-walled carbon nanotubes (SWNTs) of various chiralities. The accuracy of the O(N) description is found to be enhanced by the use of basis functions of neighboring atoms (buffer). The importance of buffer size in evaluating the simulation time, total energy, and force values together with electronic temperature has been shown. Finally, through the local density of state results, the metallic and semiconducting behavior of (10x10) armchair and (17x0) zigzag SWNT s, respectively, has been demonstrated.Comment: 15 pages, 10 figure

Over restrictive elimination of foods in children with foodallergy

Background. Previous studies demonstrated critical deficits in diagnosis and management of childhood foodallergy (FA), and recent developments in FA research support adopting a proactive approach in FA management.Our objective was to describe FA knowledge and management patterns of pediatricians.Method. We applied a 24-item survey to 170 general pediatricians, pediatric allergists and pediatricgastroenterologists practicing in Turkey.Results. Some IgE-mediated symptoms of FA such as cough, urticaria, wheezing and anaphylaxis were falselyrecognized as symptoms of non-IgE-mediated FA by 30%, 29%, 25% and 19% of the participants, respectively.By contrast, 50% of the participants falsely recognized bloody stool, a finding of IgE-mediated FA. Mostfrequently and least frequently used diagnostic tools were specific IgE (30.5%) and oral food challenge test(1.7%), respectively. Maternal diet restrictions and infant diet restrictions were advised by 82% and 82%,respectively. Percentages of physicians eliminating only 1 food were 21%, 19%; 2 foods were 15%, 11%; 3 foodswere 7%, 8%; 4-5 foods were 8%, 11%; 5 to 10 foods were 21%, 26%; and >10 foods were 28%, 25% from thematernal and infant diet, respectively. Cow’s milk, cheese, butter, yoghurt, baked milk products and hen’s eggwere the most commonly restricted items.Conclusion. Overall, FA knowledge of pediatricians was fair. Pediatricians utilize an overly restrictive approachwhen advising diet eliminations in FA. Recent developments favor a more proactive approach to induce immunetolerance and need to be encouraged in pediatric clinical practice. Future educational efforts should focus onemphasizing the deleterious effects of injudicious and extensive eliminations