The Thermal Abundance of Semi-Relativistic Relics

Approximate analytical solutions of the Boltzmann equation for particles that are either extremely relativistic or non-relativistic when they decouple from the thermal bath are well established. However, no analytical formula for the relic density of particles that are semi-relativistic at decoupling is yet known. We propose a new ansatz for the thermal average of the annihilation cross sections for such particles, and find a semi-analytical treatment for calculating their relic densities. As examples, we consider Majorana- and Dirac-type neutrinos. We show that such semi-relativistic relics cannot be good cold Dark Matter candidates. However, late decays of meta-stable semi-relativistic relics might have released a large amount of entropy, thereby diluting the density of other, unwanted relics.Comment: 22 pages, 5 figures. Comments and references adde

X-Ray Fluctuations from Locally Unstable Advection-Dominated Disks

The response of advection-dominated accretion disks to local disturbances is examined by one-dimensional numerical simulations. It is generally believed that advection-dominated disks are thermally stable. We, however, find that any disurbance added onto accretion flow at large radii does not decay so rapidly that it can move inward with roughly the free-fall velocity. Although disturbances continue to be present, the global disk structure will not be modified largely. This can account for persistent hard X-ray emission with substantial variations observed in active galactic nuclei and stellar black hole candidates during the hard state. Moreover, when the disturbance reaches the innermost parts, an acoustic wave emerges, propagating outward as a shock wave. The resultant light variation is roughly (time) symmetric and is quite reminiscent of the observed X-ray shots of Cygnus X-1.Comment: plain TeX, 11 pages, without figures; to be published in ApJ Lette

Transitive X-ray spectrum and PeV gamma-ray cutoff in the M87 jet: Electron "Pevatron"

We propose a modified version of the X-ray spectral index and an intrinsic cutoff frequency of inverse Compton radiation from the brightest knot of the M87 jet, in conjunction with an application of the new conceptions of injection and diffusive shock acceleration (DSA) of electrons in magnetized filamentary plasma to the specified source. The drop of the X-ray flux density in a transitive frequency region is associated with the interplay of ordinary synchrotron cooling and weaker magnetic fields concomitant with the smaller scale filaments that allow the electron injection, while the radio-optical synchrotron continuum is dominantly established by the major electrons that are quasi-secularly bound to larger filaments. With reference to, particularly, the updated external Compton model, we demonstrate that in the Klein-Nishina regime fading inverse Comptonization, the injected electrons can be stochastically energized up to a Lorentz factor as high as $5\times 10^{10}$ in the temporal competition with diffuse synchrotron cooling; this value is larger than that attainable for a simple DSA scenario based on the resonant scattering diffusion of the gyrating electrons bound to a supposed magnetic field homogeneously pervading the entire knot. The upper limits of the photon frequency boosted via conceivable inverse Compton processes are predicted to be of the common order of $\sim 10^{30}$ Hz. The variability of the broadband spectrum is also discussed in comparison to the features of a blazar light curve. The present scenario of a peta-eV (PeV; $10^{15}$ eV) electron accelerator, the "Pevatron," might provide some guidance for exploring untrod hard X-ray and gamma-ray bands in forthcoming observations.Comment: 34 pages, 6 figures, matches version published in Ap

Rehabilitation of Devastated Peat Lands and Establishment of Sustainable Agro-systems Through Buffer Zone Planning in Central Kalimantan

Under the slogan of sustainable development, forests on the peat swamp and wetland area have been destroyed in tropical area.Needless to say, since it is very difficult to develop peat swamp and wetland, those huge areas still remain in natural or sub-natural conditions.Therefore, those areas have been considering as the key ecosystem for not only reserving bio resources and biodiversity, but also reducing carbon efflux owing to degradation of peat,stocking of carbon in forests,or controlling water balance.However, now, the peat swamp and wetland in tropical area face to the crisis of disappearance due to human impact,which isaccelerated by recent abnormal and unusual global climate changes

Spin and chirality orderings of the one-dimensional Heisenberg spin glass with the long-range power-law interaction

The ordering of the one-dimensional Heisenberg spin glass interacting via the long-range power-law interaction is studied by Monte Carlo simulations. Particular attention is paid to the possible occurrence of the ``spin-chirality decoupling'' for appropriate values of the power-law exponent \sigma. Our result suggests that, for intermediate values of $\sigma$, the chiral-glass order occurs at finite temperatures while the standard spin-glass order occurs only at zero temperature.Comment: Proceedings of the Highly Frustrated Magnetism (HFM2006) conference. To appear in a special issue of J. Phys. Condens. Matte

Magnetic structure and spin dynamics of quasi-one-dimensional spin-chain antiferromagnet BaCo2V2O8

We report a neutron diffraction and muon spin relaxation muSR study of static and dynamical magnetic properties of BaCo2V2O8, a quasi-one-dimensional spin-chain system. A proposed model for the antiferromagnetic structure includes: a propagation vector k_AF = (0, 0, 1), independent of external magnetic fields for fields below a critical value H_c(T). The ordered moments, of 2.18 \mu_B per Co ion, are aligned along the crystallographic c-axis. Within the screw chains, along the c axis, the moments are arranged antiferromagnetically. In the basal planes the spins are arranged ferromagnetically (forming zig-zags paths) along one of the axis and antiferromagnetically along the other. The temperature dependence of the sub-lattice magnetization is consistent with the expectations of the 3D Ising model. A similar behavior is observed for the internal static fields at different muon stopping sites. Muon time spectra measured at weak longitudinal fields and temperatures much higher than T_N can be well described using a single muon site with an exponential muon spin relaxation that gradually changes into an stretched exponential on approaching T_N. The temperature-induced changes of the relaxation suggest that the Co fluctuations dramatically slow down and the system becomes less homogeneous as it approaches the antiferromagnetic state.Comment: 7 pages, 9 figure

A Learning Model for Cultivating Self-Awareness on Human Decision-Making in an Emergency Situation

People may have knowledge to handle a certain situation; however, often they might not be able to perform their behaviour well when encountering the actual situation. There are knowledge-to-action gaps that make ones do not aware the existing knowledge and act improperly. This research aims to motivate learner to become aware of their thought by proposing 1) a learning model using “surprise” as a trigger for motivating learner to realize their thinking process; and 2) a Relax-Half-Baked Microworld and its decision-making model which are used as a simulated environment. Learners could modify parameters, anticipate expected outcomes and compare observed simulated outcomes with their expected ones. Learners would feel surprise from unexpected results in the comparison, and used it to reflect their thought and to be aware of how did they make decision

Diversity of Aphyllophorales Fungi Isolated From Tanjung Puting National Park, Central Kalimantan and Its Potentiality for Lignin Decomposition

A total of fifty-three samples of fungal basidiocarp were collected from peat area in Tanjung Puting National Park, Central Kalimantan, Indonesia. These samples are mostly determined to genus until more studies are available.The fungi were isolated on CMA medium then the isolated strains were purified on PDA medium. The fungi belong to at least 3 families of Aphyllophorales, however there were a wide diversity in the genus with respect to macroscopic examination.An agar plate screening procedures was developed for the rapid selection of fungi and estimation of their capacity for lignin-decomposer. The test is based on the visualization and interpretation of the formation of halo zone or decolourization process in well-defined agar medium containing Poly R-478. The selected isolates were also tested in to rhemazol brilliant blue R salt (RBBR) medium. Five isolates had the ability to decolourize either Poly R-478 or RBBR. These isolates showed a qualitative lignin decomposition although a comparative study of selected fungi revealed the difference potentiality. The highest loss of lignin was 28.18% and attempts have been made to determine the unidentified fungi, which is resupinate type, by direct sequencing of 18s ribosomal DNA (rDNA)