Heat fluctuations in Ising models coupled with two different heat baths

Monte Carlo simulations of Ising models coupled to heat baths at two different temperatures are used to study a fluctuation relation for the heat exchanged between the two thermostats in a time $\tau$. Different kinetics (single--spin--flip or spin--exchange Kawasaki dynamics), transition rates (Glauber or Metropolis), and couplings between the system and the thermostats have been considered. In every case the fluctuation relation is verified in the large $\tau$ limit, both in the disordered and in the low temperature phase. Finite-$\tau$ corrections are shown to obey a scaling behavior.Comment: 5 pages, 2 figures. To be published in Journal of Physics A: Mathematical and Theoretical as fast track communicatio

Energy and Heat Fluctuations in a Temperature Quench

Fluctuations of energy and heat are investigated during the relaxation following the instantaneous temperature quench of an extended system. Results are obtained analytically for the Gaussian model and for the large $N$ model quenched below the critical temperature $T_C$. The main finding is that fluctuations exceeding a critical threshold do condense. Though driven by a mechanism similar to that of Bose-Einstein condensation, this phenomenon is an out-of-equilibrium feature produced by the breaking of energy equipartition occurring in the transient regime. The dynamical nature of the transition is illustrated by phase diagrams extending in the time direction.Comment: To be published in the Proceedings of the Research Program "Small system non equilibrium fluctuations, dynamics and stochastics, and anomalous behavior", Kavli Institute for Theoretical Physics China, July 2013. 40 pages, 9 figure

Study of a high spatial resolution 10B-based thermal neutron detector for application in neutron reflectometry: the Multi-Blade prototype

Although for large area detectors it is crucial to find an alternative to detect thermal neutrons because of the 3He shortage, this is not the case for small area detectors. Neutron scattering science is still growing its instruments' power and the neutron flux a detector must tolerate is increasing. For small area detectors the main effort is to expand the detectors' performances. At Institut Laue-Langevin (ILL) we developed the Multi-Blade detector which wants to increase the spatial resolution of 3He-based detectors for high flux applications. We developed a high spatial resolution prototype suitable for neutron reflectometry instruments. It exploits solid 10B-films employed in a proportional gas chamber. Two prototypes have been constructed at ILL and the results obtained on our monochromatic test beam line are presented here

Fluctuation relations in non-equilibrium stationary states of Ising models

Fluctuation relations for the entropy production in non equilibrium stationary states of Ising models are investigated by Monte Carlo simulations. Systems in contact with heat baths at two different temperatures or subject to external driving will be studied. In the first case, by considering different kinetic rules and couplings with the baths, the behavior of the probability distributions of the heat exchanged in a time $\tau$ with the thermostats, both in the disordered and in the low temperature phase, are discussed. The fluctuation relation is always verified in the large $\tau$ limit and deviations from linear response theory are observed. Finite-$\tau$ corrections are shown to obey a scaling behavior. In the other case the system is in contact with a single heat bath but work is done by shearing it. Also for this system the statistics collected for the mechanical work shows the validity of the fluctuation relation and preasymptotic corrections behave analogously to the case with two baths.Comment: 9 figure

characterization and manufacturing of a paraffin wax as fuel for hybrid rockets

The hybrid propulsion performed with paraffin waxes exhibits most attractive capabilities compared to solid or liquid engines, e.g., throttleability and re-ignition, alongside higher regression rates compared to the conventional hydroxyl terminated polybutadiene (HTPB) hybrid fuel. This is because the paraffin wax forms a thin and hydro-dynamically unstable liquid layer, and then enhances the regression rate with the entrainment of droplets from the liquid-gas interface. Nevertheless, some critical open points on the manufacturing of the paraffin fuel grains still persist, because the paraffin wax exhibits high shrinkage during the solidification phase, leading to the formation of cavities, cracks and internal rips, which may be detrimental to the mechanical properties and the structural integrity of the fuel grain. In this context, this paper deals with a wide calorimetric, thermo-mechanical and physical characterization of the paraffin wax selected to manufacture the hybrid rocket engines (HRE) fuel grain, in order to gain a thorough knowledge of the material necessary to avoid the formation of critical defects. Several manufacturing methods were investigated, and it was found that only laboratory scale processes, based on the use of a heated circular mould-piston apparatus, are able to avoid the formation of critical defects, with the application of both high temperature and pressure. Keywords: Paraffin wax, Hybrid rockets, Manufacturing, SASOL® 0907, Regression rat

Superhydrophobic coatings as anti-icing systems for small aircraft

Traditional anti-icing/de-icing systems, i.e., thermal and pneumatic, in most cases require a power consumption not always allowable in small aircraft. Therefore, the use of passive systems, able to delay the ice formation, or reduce the ice adhesion strength once formed, with no additional energy consumption, can be considered as the most promising solution to solve the problem of the ice formation, most of all, for small aircraft. In some cases, the combination of a traditional icing protection system (electrical, pneumatic, and thermal) and the passive coatings can be considered as a strategic instrument to reduce the energy consumption. The effort of the present work was to develop a superhydrophobic coating, able to reduce the surface free energy (SFE) and the work of adhesion (WA) of substrates, by a simplified and non-expensive method. The developed coating, applied as a common paint with an aerograph, is able to reduce the SFE of substrates by 99% and the WA by 94%. The effects of both chemistry and surface morphology on the wettability of surfaces were also studied. In the reference samples, the higher the roughness, the lower the SFE and the WA. In coated samples with roughness ranging from 0.4 and 3 μm no relevant variations in water contact angle, nor in SFE andWA were observed

Manajemen Pendidikan

Perubahan sosial dan globalisasi telah menimbulkan ekonomi pengetahuan baru di mana isu esensialnya adalah apa yang kita sebut sebagai pengetahuan dalam sebuah organisasi, bagaimana pengetahuan ini ditransmisikan dan dipelihara, siapa yang memilikinya, dan bagaimana ini menjadi milik bersama. Demikianlah, globalisasi mempengaruhi segi-segi ekonomi, politik, kultural, teknis, dan sosial di semua negara, yang secara tak terelakkan membawa pada ketidakpastian (uncertainty); misalnya, dalam pasar kerja yang sedang berubah. Di sinilah manajemen pendidikan, sebagai suatu ilmu khusus yang menangani pengorganisasian pendidikan, perlu memberikan jawaban pada ketidakpastian tadi dalam rangka perannya sebagai perangkat untuk memerangi eksklusi sosial. Manajemen pendidikan dituntut untuk memposisikan kembali (repositioning) lembaga pendidikan untuk memenuhi keperluan abad ‘super-kompleks.

Addition of the apical oblique projection increases the detection of acute traumatic shoulder abnormalities in adults

Purpose Plain radiographic evaluation of acute shoulder trauma in adults requires a minimum of two projections, commonly the anteroposterior (AP) and lateral scapular projections, with additional projections taken for diagnosis. The aim of this retrospective study was to determine whether the addition of the apical oblique (AO) projection to the AP and lateral scapular projections increases the number and/or alters the types of abnormalities detected in the examination of acute shoulder trauma. Methods Examinations of 56 adults who had undergone three-projection (AP, lateral scapular, AO) radiographic shoulder examination for acute trauma were allocated into two-projection (AP, lateral scapular) and three-projection cases and assessed by a radiologist. The differences in number and types of abnormalities between the two-projection and three-projection cases were quantified using the one-tailed t test and chi-square goodness-of-fit test, respectively. Results Test-retest reliability was moderate (intra-class correlation coefficient [95%CI], 0.56 [0.15 to 0.80]) for number, and almost perfect (kappa [95%CI], 0.94 [0.85 to 1.00]) for types, of abnormalities detected. There was a significant increase in the number of abnormalities detected across all three-projection versus two-projection cases (difference in means [95%CI], 0.20 [0.01 to 0.39]) and for fractures (difference in means [95%CI], 0.30 [0.11 to 0.49]), but no difference in the types of abnormalities detected (χ 2 = 4.7, p = 0.19). Conclusion This study suggests that adding the AO projection to two-projection examination of acute shoulder trauma increases the number of abnormalities detected; this has potential implications for patient management. Further research investigating differences in types of abnormalities detected between two-projection and three-projection cases is warranted

Some Restrictions Abroad Affecting Corporations

A neutron detector concept based on solid layers of boron carbide enriched in 1 B has been in development for the last few years as an alternative for He-3 by collaboration between the ILL, ESS and Linkoping University. This Multi-Grid detector uses layers of aluminum substrates coated with (B4C)-B-10 on both sides that are traversed by the incoming neutrons. Detection is achieved using a gas counter readout principle. By segmenting the substrate and using multiple anode wires, the detector is made inherently position sensitive. This development is aimed primarily at neutron scattering instruments with large detector areas, such as time-of-flight chopper spectrometers. The most recent prototype has been built to be interchangeable with the He-3 detectors of IN6 at ILL. The 1 B detector has an active area of 32 x 48 cm(2). It was installed at the IN6 instrument and operated for several weeks, collecting data in parallel with the regularly scheduled experiments, thus providing the first side-by-side comparison with the conventional He-3 detectors. Results include an efficiency comparison, assessment of the in-detector scattering contribution, sensitivity to gamma-rays and the signal-to-noise ratio in time-of-flight spectra. The good expected performance has been confirmed with the exception of an unexpected background count rate. This has been identified as natural alpha activity in aluminum. New convertor substrates are under study to eliminate this source of background

Invading parasites: spillover of an alien nematode reduces survival in a native species

It is widely assumed that spillover of alien parasites to native host species severely impacts na\uefve populations, ultimately conferring a competitive advantage to invading hosts that introduced them. Despite such host-switching events occurring in biological invasions, studies demonstrating the impact of alien macroparasites on native animal hosts are surprisingly few. In Europe, native red squirrels (Sciurus vulgaris) are replaced by introduced North American grey squirrels (S. carolinensis) mainly through resource competition, and, only in the United Kingdom and Ireland, by competition mediated by a viral disease. In Italy such disease is absent, but spillover of an introduced North American nematode (Strongyloides robustus) from grey to red squirrels is known to occur. Here, we used long-term (9 years) capture-mark-recapture and parasitological data of red squirrels in areas co-inhabited by grey squirrels in Northern Italy to investigate the impact of this alien helminth on na\uefve native squirrels\u2019 body mass, local survival, and reproduction of females. We found no negative effect of the alien parasite on body mass or reproductive success, but intensity of infection by S. robustus reduced survival of both male and female squirrels. Significantly, survival of squirrels co-infected by their native nematode, Trypanoxyuris sciuri, was less affected by S. robustus, suggesting a protective effect of the native helminth against the new infection. Hence, we demonstrate that alien S. robustus spillover adds to the detrimental effects of resource competition and stress induced by grey squirrels, further reducing the fitness of the native species in the presence of the invasive competitor