Flux Expulsion - Field Evolution in Neutron Stars

Models for the evolution of magnetic fields of neutron stars are constructed, assuming the field is embedded in the proton superconducting core of the star. The rate of expulsion of the magnetic flux out of the core, or equivalently the velocity of outward motion of flux-carrying proton-vortices is determined from a solution of the Magnus equation of motion for these vortices. A force due to the pinning interaction between the proton-vortices and the neutron-superfluid vortices is also taken into account in addition to the other more conventional forces acting on the proton-vortices. Alternative models for the field evolution are considered based on the different possibilities discussed for the effective values of the various forces. The coupled spin and magnetic evolution of single pulsars as well as those processed in low-mass binary systems are computed, for each of the models. The predicted lifetimes of active pulsars, field strengths of the very old neutron stars, and distribution of the magnetic fields versus orbital periods in low-mass binary pulsars are used to test the adopted field decay models. Contrary to the earlier claims, the buoyancy is argued to be the dominant driving cause of the flux expulsion, for the single as well as the binary neutron stars. However, the pinning is also found to play a crucial role which is necessary to account for the observed low field binary and millisecond pulsars.Comment: 23 pages, + 7 figures, accepted for publication in Ap

Arbitrating in Thailand

Thailand has one of the developing world\u27s strongest economies. The growth of the Thai economy has been fueled largely by foreign investment. As foreign investment in Thailand continues, disputes between foreign enterprises and their Thai counterparts are inevitable. One method for resolving these disputes is through arbitration at the new Arbitration Office in The Ministry of Justice. This note examines Thailand\u27s 1987 Arbitration Act, the 1990 Arbitration Rules, and some other factors involved in arbitrating in Thailand. The note concludes that many of the potential advantages of arbitration are lost under the Thai rules and therefore arbitrating in Thailand is only marginally more attractive to the foreign investor than litigating in the Thai national courts

Path Integral Approach to Fermionic Vacuum Energy in Non-parallel D1-Branes

The fermionic one loop vacuum energy of the superstring theory in a system of non-parallel D1-branes is derived by applying the path integral formalism.Comment: 7 pages, no figur

Nutrient digestibility coefficients of diets with varying energy to protein ratio for Japanese flounder, Paralichthys olivaceus

A laboratory trial was conducted in a sea water recirculatory system to study the nutrient digestibility coefficients of diets with varying energy to protein ratios in Japanese flounder Paralicthys olivaceus. Six different experimental diets with two protein levels (45 and 55%) having six different energy to protein ratio of 87, 90, 94, 107, 110 and 114 were formulated using white fish meal and casein as protein sources. The results of the study showed that the apparent protein digestibility (APD) value ranged between 90.59 to 91.61% and there were no significant differences (P>0.05) between the APD values of diets 1, 2, 3, 4 and 6. The apparent lipid digestibility (ALD) values of diets ranged between 88.24 to 90.18%. The apparent energy digestibility (AED) values ranged between 80.55 to 87.52% with diet 3 producing significantly the highest AED value. In general, except in diet 1 the ALD and AED values increased with the increase of dietary lipid at both protein levels. The results of the present investigation indicated that Japanese flounder can efficiently digest the dietary nutrients at varying energy to protein ratios

Spin-down Rate of Pinned Superfluid

The spinning down (up) of a superfluid is associated with a radial motion of its quantized vortices. In the presence of pinning barriers against the motion of the vortices, a spin-down may be still realized through ``random unpinning'' and ``vortex motion,'' as two physically separate processes, as suggested recently. The spin-down rate of a pinned superfluid is calculated, in this framework, by directly solving the equation of motion applicable to only the unpinned moving vortices, at any given time. The results indicate that the pinned superfluid in the crust of a neutron star may as well spin down at the same steady-state rate as the rest of the star, through random unpinning events, while pinning conditions prevail and the superfluid rotational lag is smaller than the critical lag value.Comment: to appear in ApJ (vol. 649 ?

A Comparative Study on Machining Capabilities of Wet and Dry Nanoscale Electro-machining

Presently, the nano scale electro-machining (nano-EM) process has been demonstrated in both the liquid and air dielectric mediums, which are known as wet and dry nano-EM respectively. In the current study, two important aspects of the nano-EM have been investigated: the minimum possible feature dimension and mass fabrication capability of nano-EM. Firstly, the investigation has been done on the capability of machining graphene at atomic scale with focus on obtaining smallest possible nano-feature using the wet nano-EM. Secondly, the ability of the nano-EM process for the fabrication of arrays of nano-holes has been investigated using dry nano-EM. It was found that nano-features of 3 to 4 nm could be machined in graphene surfaces revealing the atomic arrangement of carbon using the wet nano-EM process. The dry nano-EM was found to be capable of fabricating arrays of nano-features making it more suitable for mass fabrication. The field induced evaporation of materials from the tool during dry nano-EM retained the quality of tool electrode, thus making the process capable of fabricating more than 100 nano features in a single step. It was found that the material removal mechanism influenced the machining capability of the process. The mechanism of material removal in the wet nano-EM was associated with the dielectric breakdown of liquid n-decane generating intense heat for ionization, evaporation, and melting of materials. On the other hand, the material removal mechanism of dry nano-EM was associated with the breakdown of air, which generated intense heat at the gap between the nano-EM tool and the workpiece causing localized ionization and evaporation

A Comparative Study on Machining Capabilities of Wet and Dry Nanoscale Electro-machining

Presently, the nano scale electro-machining (nano-EM) process has been demonstrated in both the liquid and air dielectric mediums, which are known as wet and dry nano-EM respectively. In the current study, two important aspects of the nano-EM have been investigated: the minimum possible feature dimension and mass fabrication capability of nano-EM. Firstly, the investigation has been done on the capability of machining graphene at atomic scale with focus on obtaining smallest possible nano-feature using the wet nano-EM. Secondly, the ability of the nano-EM process for the fabrication of arrays of nano-holes has been investigated using dry nano-EM. It was found that nano-features of 3 to 4 nm could be machined in graphene surfaces revealing the atomic arrangement of carbon using the wet nano-EM process. The dry nano-EM was found to be capable of fabricating arrays of nano-features making it more suitable for mass fabrication. The field induced evaporation of materials from the tool during dry nano-EM retained the quality of tool electrode, thus making the process capable of fabricating more than 100 nano features in a single step. It was found that the material removal mechanism influenced the machining capability of the process. The mechanism of material removal in the wet nano-EM was associated with the dielectric breakdown of liquid n-decane generating intense heat for ionization, evaporation, and melting of materials. On the other hand, the material removal mechanism of dry nano-EM was associated with the breakdown of air, which generated intense heat at the gap between the nano-EM tool and the workpiece causing localized ionization and evaporation

A comparative study of the dry and wet nano-scale electro-machining

In recent years, a nano-electromachining (nano-EM) process based on a scanning tunneling microscope (STM) platform has been demonstrated. Nano-EM is capable of machining nano-features, under both, liquid dielectric (wet nano-EM) and air dielectric (dry nano-EM) media. The objective of this paper is to present a comparative study between the wet and dry nano-EM processes based on process mechanism, machining performance, consistency and dimensional repeatability of these two processes. The comparison of the two processes has been conducted at near field nano-EM, where the gap between the tool electrode and workpiece is 2 nm and the machining is performed at room temperature and pressure (macroscopically). The major differences in the process mechanism are due to the media at dielectric interface, the breakdown field strength and breakdown characteristics of two dielectrics and therefore, the material removal mechanism. It is reported that the material removal mechanism of wet nano-EM is associated with field emission-assisted avalanche in nano-confined liquid dielectric, whereas, the material removal mechanism in dry nano-EM is associated with field-induced evaporation of material. The differences have also been observed in the machining performance, dimensions of the machined features and repeatability of the nanoscale machined features. The self-tip-sharpening process with the continuation of machining has added several advantages to dry nano-EM over wet nano-EM in terms of dimensions of the nanoscale features, repeatability and machining performance