Seed Magnetic Fields Generated by Primordial Supernova Explosions

The origin of the magnetic field in galaxies is an open question in astrophysics. Several mechanisms have been proposed related, in general, with the generation of small seed fields amplified by a dynamo mechanism. In general, these mechanisms have difficulty in satisfying both the requirements of a sufficiently high strength for the magnetic field and the necessary large coherent scales. We show that the formation of dense and turbulent shells of matter, in the multiple explosion scenario of Miranda and Opher (1996, 1997) for the formation of the large-scale structures of the Universe, can naturally act as a seed for the generation of a magnetic field. During the collapse and explosion of Population III objects, a temperature gradient not parallel to a density gradient can naturally be established, producing a seed magnetic field through the Biermann battery mechanism. We show that seed magnetic fields $\sim 10^{-12}-10^{-14}G$ can be produced in this multiple explosion scenario on scales of the order of clusters of galaxies (with coherence length $L\sim 1.8Mpc$) and up to $\sim 4.5\times 10^{-10}G$ on scales of galaxies ($L\sim 100 kpc$).Comment: Accepted for publication in MNRAS, 5 pages (MN plain TeX macros v1.6 file). Also available at http://www.iagusp.usp.br/~oswaldo (click "OPTIONS" and then "ARTICLES"

Iraq and Afghanistan veterans’ experiences living with their parents after separation from the military

When military service members separate from the military, many return to their families of origin, living with their parents for a period of several weeks to years. While research with veterans and their spouses has documented the particular strain of this reintegration period on veterans and their partners, little research to date has examined veterans’ experiences living with their parents. The present study sought to fill this research gap by investigating veterans’ experiences living with their parents using qualitative, in-depth interviews with Iraq and Afghanistan veterans in California. Overall, veterans appreciated the instrumental and emotional support their parents provided when they separated. However, in some cases, living with parents also produced conflict and strain. In situations where adult veteran children had difficulty with the transition to civilian life or returned with mental health problems, parents were often the first to identify these problems and to support their children in accessing appropriate care. We analyze these findings in light of family systems theory, identifying ways in which adult veteran children continue a process of differentiation while living with their parents and maintaining emotional connectedness. We suggest ways that clinicians can better support veterans and their parents through the reintegration period and recommend that programming for military families explicitly include parents of service members in addition to conjugal families

Management arrangements for accommodating nonrice crops in rice-based irrigation systems: Proceedings of the First Progress Review and Coordination Workshop of the Research Network on Irrigation Management for Crop Diversification in Rice-Based Systems (IMCD), held in Quezon City, the Philippines, 10-14 December 1990

Irrigation management / Crops / Diversification / Rice / Irrigated farming / Policy / Research / Sri Lanka / Bangladesh / India / Indonesia / Malaysia / Nepal / Philippines / Thailand

A generalized vortex lattice method for subsonic and supersonic flow applications

If the discrete vortex lattice is considered as an approximation to the surface-distributed vorticity, then the concept of the generalized principal part of an integral yields a residual term to the vorticity-induced velocity field. The proper incorporation of this term to the velocity field generated by the discrete vortex lines renders the present vortex lattice method valid for supersonic flow. Special techniques for simulating nonzero thickness lifting surfaces and fusiform bodies with vortex lattice elements are included. Thickness effects of wing-like components are simulated by a double (biplanar) vortex lattice layer, and fusiform bodies are represented by a vortex grid arranged on a series of concentrical cylindrical surfaces. The analysis of sideslip effects by the subject method is described. Numerical considerations peculiar to the application of these techniques are also discussed. The method has been implemented in a digital computer code. A users manual is included along with a complete FORTRAN compilation, an executed case, and conversion programs for transforming input for the NASA wave drag program

Propagação vegetativa do mogno (Swietenia macrophylla King) por enraizamento de estacas semilenhosas em câmara úmida.

A exploração predatória do mogno representa uma ameaça à sobrevivência da espécie, provocando a destruição da maior parte do germoplasma, especialmente daquelas árvores com as características mais desejáveis para a produção de madeira, às quais representam alto potencial de conservação "in situ" como plantas matrizes. Diante desta realidade e dada a importância da espécie para a produção de madeira de alto valor, são necessários estudos com o objetivo de desenvolver um método prático de reprodução vegetativa para estabelecer uma estratégia de conservação e reprodução do germoplasma de melhor qualidade. Entre os métodos de propagação vegetativa recomendados a espécies tropicais para produção de madeira, destaca-se o enraizamento de estacas semilenhosas em câmara úmida. O objetivo deste trabalho foi determinar a eficiência de diferentes substratos e concentração de ácido indolbutírico (AIB) no enraizamento de estacas semilenhosas de S. macrophylla, utilizando uma câmara propagadora de subirrigação.bitstream/item/164612/1/3990.pd

A long-range and long-life telemetry data-acquisition system for heart rate and multiple body temperatures from free-ranging animals

The system includes an implantable transmitter, external receiver-retransmitter collar, and a microprocessor-controlled demodulator. The size of the implant is suitable for animals with body weights of a few kilograms or more; further size reduction of the implant is possible. The ECG is sensed by electrodes designed for internal telemetry and to reduce movement artifacts. The R-wave characteristics are then specifically selected to trigger a short radio frequency pulse. Temperatures are sensed at desired locations by thermistors and then, based on a heartbeat counter, transmitted intermittently via pulse interval modulation. This modulation scheme includes first and last calibration intervals for a reference by ratios with the temperature intervals to achieve good accuracy even over long periods. Pulse duration and pulse sequencing are used to discriminate between heart rate and temperature pulses as well as RF interference