Semiclassical degeneracies and ordering for highly frustrated magnets in a field

We discuss ground state selection by quantum fluctuations in frustrated magnets in a strong magnetic field. We show that there exist dynamical symmetries -- one a generalisation of Henley's gauge-like symmetry for collinear spins, the other the quantum relict of non-collinear weathervane modes -- which ensure a partial survival of the classical degeneracies. We illustrate these for the case of the kagome magnet, where we find zero-point energy differences to be rather small everywhere except near the collinear `up-up-down` configurations, where there is rotational but not translational symmetry breaking. In the effective Hamiltonian, we demonstrate the presence of a term sensitive to a topological `flux'. We discuss the connection of such problems to gauge theories by casting the frustrated lattices as medial lattices of appropriately chosen simplex lattices, and in particular we show how the magnetic field can be used to tune the physical sector of the resulting gauge theories.Comment: 10 pages, 8 figure

Monte Carlo Performance Studies of Candidate Sites for the Cherenkov Telescope Array

The Cherenkov Telescope Array (CTA) is the next-generation gamma-ray observatory with sensitivity in the energy range from 20 GeV to beyond 300 TeV. CTA is proposed to consist of two arrays of 40-100 imaging atmospheric Cherenkov telescopes, with one site located in each of the Northern and Southern Hemispheres. The evaluation process for the candidate sites for CTA is supported by detailed Monte Carlo simulations, which take different attributes like site altitude and geomagnetic field configuration into account. In this contribution we present the comparison of the sensitivity and performance of the different CTA site candidates for the measurement of very-high energy gamma rays.Comment: In Proceedings of the 34th International Cosmic Ray Conference (ICRC2015), The Hague, The Netherlands. All CTA contributions at arXiv:1508.0589

Serum testosterone in Arabian stallions during breeding and non-breeding seasons in Iran

The study was conducted to investigate the serum testosterone concentrations of Arabian stallions during breeding and non-breeding seasons under natural photoperiodic condition in west south of Iran (Khuzestan Province; latitude 48:40°N, longitude 31:20°E and altitude 22.5 m). The blood samples (10 ml) were collected from the jugular vein, and it stood at room temperature for 3 h and was centrifuged. The sera were kept at -20°C until assayed by radioimmunoassay. The results show that total serum testosterone levels (ng/ml) in Arabian stallions was higher in May to June (Summer Solstice; 1.08±0.078) than in November to December (Winter Solstice; 0.65±0.11) (p<0.05). We conclude that serum testosterone concentration during the non-breeding season is lower than that of the breeding season. The results confirm a seasonal rhythm in the reproductive cycle of Arabian stallions over the year in this specific region.Key words: Arabian stallion, season, testosterone, photoperiod

Theoretical study of isolated dangling bonds, dangling bond wires and dangling bond clusters on H:Si(100)-(2×\times1) surface

We theoretically study the electronic band structure of isolated unpaired and paired dangling bonds (DB), DB wires and DB clusters on H:Si(100)-(2$\times$1) surface using Extended H\"uckel Theory (EHT) and report their effect on the Si band gap. An isolated unpaired DB introduces a near-midgap state, whereas a paired DB leads to $\pi$ and $\pi^*$ states, similar to those introduced by an unpassivated asymmetric dimer (AD) Si(100)-(2$\times$1) surface. Such induced states have very small dispersion due to their isolation from the other states, which reside in conduction and valence band. On the other hand, the surface state induced due to an unpaired DB wire in the direction along the dimer row (referred to as $[\bar{1}10]$), has large dispersion due to the strong coupling between the adjacent DBs, being 3.84$\AA$ apart. However, in the direction perpendicular to the dimer row (referred to as [110]), due to the reduced coupling between the DBs being 7.68$\AA$ apart, the dispersion in the surface state is similar to that of an isolated unpaired DB. Apart from this, a paired DB wire in $[\bar{1}10]$ direction introduces $\pi$ and $\pi^*$ states similar to those of an AD surface and a paired DB wire in [110] direction exhibits surface states similar to those of an isolated paired DB, as expected. Besides this, we report the electronic structure of different DB clusters, which exhibit states inside the band gap that can be interpreted as superpositions of states due to unpaired and paired DBs.Comment: 7 pages, 10 figure, 1 tabl

Second large-scale Monte Carlo study for the Cherenkov Telescope Array

The Cherenkov Telescope Array (CTA) represents the next generation of ground based instruments for Very High Energy gamma-ray astronomy. It is expected to improve on the sensitivity of current instruments by an order of magnitude and provide energy coverage from 20 GeV to more than 200 TeV. In order to achieve these ambitious goals Monte Carlo (MC) simulations play a crucial role, guiding the design of CTA. Here, results of the second large-scale MC production are reported, providing a realistic estimation of feasible array candidates for both Northern and Sourthern Hemisphere sites performance, placing CTA capabilities into the context of the current generation of High Energy $\gamma$-ray detectors.Comment: In Proceedings of the 34th International Cosmic Ray Conference (ICRC2015), The Hague, The Netherlands. All CTA contributions at arXiv:1508.0589

Experiment of oxygenated fuel on diesel engine: Performance, emission and particulate matter

The main purpose of the study is to characterise the effects of diesel, biodiesel blends B5M10 and B10M10 and emulsion fuels B5M10E3 and B10M10E3 as fuels for the impact on particulate matter emission. Engine tests have been performed to obtain results of engine performance, gas emission and particulate matter with various cycles. Excel analysis methods were used to analysethe data obtained.The B5M10E3 produces lowe

Wave climate for inland vessels between Zeebrugge and the mouth of the Western Scheldt: estimation by the Belgian coast model in SWAN

The Masterplan 'Vlaamse Baaien' outlines the need to develop an integrated vision for the Belgian coast. One of the Masterplan’s goals is to achieve a win-win situation between coastal protection and the maintenance and improvement of the maritime access to the port of Zeebrugge.The hinterland connection of the port of Zeebrugge by means of inland vessels is a major issue. Therefore, a specific type of inland vessels is conditionally allowed to make use of the 16 nautical miles long sea trajectory between Zeebrugge and the mouth of the Western Scheldt estuary to connect the port with the inland waterway network.Detailed information about the wave climate in the area between the eastern dam of the port of Zeebrugge, Pas van het Zand, Scheur-Oost/Wielingen, Vlissingen, Breskens and the coastline is essential to maximize the efficiency of the sea-river traffic in the present situation, and to decrease the requirements of inland vessels for safe navigation on a coastal route between the port of Zeebrugge and the mouth of the Western Scheldt.The existing project focuses on the model set-up and calculation of the detailed wave climate between Zeebrugge and the mouth of the Western Scheldt estuary in the present situation and also a future configuration for wind, wave and water level conditions throughout the year 2013 by means of the validated numerical model. The result of the simulation are delivered to the client for the further analysis (e.g. shading effects of new islands scenarios for the ship navigation). Research results can be used for the further analysis of the navigation of all vessels which are making use of the present route and future alternative routes. Besides, it can serve as a basis to evaluate the impact of measures on the response of inland vessels

Collective character of spin excitations in a system of Mn2+^{2+} spins coupled to a two-dimensional electron gas

We have studied the low energy spin excitations in n-type CdMnTe based dilute magnetic semiconductor quantum wells. For magnetic fields for which the energies for the excitation of free carriers and Mn spins are almost identical an anomalously large Knight shift is observed. Our findings suggests the existence of a magnetic field induced ferromagnetic order in these structures, which is in agreement with recent theoretical predictions [J. K{\"o}nig and A. H. MacDonald, submitted Phys. Rev. Lett. (2002)]Comment: 4 figure

Statistical Effects and the Black Hole/D-brane Correspondence

The horizon area and curvature of three-charge BPS black strings are studied in the D-brane ensemble for the stationary black string. The charge distributions along the string are used to translate the classical expressions for the horizon area and curvature of BPS black strings with waves into operators on the D-brane Hilbert space. Despite the fact that any `wavy' black string has smaller horizon area and divergent curvature, the typical values of the horizon area and effects of the horizon curvature in the D-brane ensemble deviate negligibly from those of the original stationary black string in the limit of large integer charges. Whether this holds in general will depend on certain properties of the quantum bound states.Comment: 13 pages, RevTex, small errors corrected, some interpretation changed in light of new result