Estimation of Gas Permeabilities for the Maricopa Site, Arizona

Upward and downward migration of gases from waste-disposal facilities is a critical issue for low-level radioactive waste disposal. Gaseous radionuclides in low-level waste include H-3, C-14, and Rn-222. Upward migration of gases to the surface can be important, particularly during operation of the facility (Kozak and Olague, 1994). High tritium values (for example 1,100 TU at 24 m depth, 162 TU at 109 m depth) have been found adjacent to the Beatty site, Nevada, that cannot readily be explained by liquid or combined liquid and vapor transport (Prudic and Striegl, 1995; Striegl et al., 1996). Because disposal practices at Beatty varied in the past and included disposal of as much as 2,000 m3 of liquid waste, further research in tritium movement at Beatty is warranted. Transport mechanisms for gases include not only diffusion but also advection. Analysis of gas transport is important at many low-level waste disposal facilities as shown by the intensive program to monitor concentrations and concentration gradients of gaseous radionuclides proposed for the California low-level radioactive waste disposal facility (Harding Lawson & Assoc., 1991). Performance assessment calculations require information on parameters related to gas transport to predict long-term migration of gases in the subsurface. The purpose of this study is to evaluate different techniques of estimating gas transport parameters and monitoring subsurface gas migration. The objective of this study is to examine different techniques for evaluating gas permeability. Pneumatic pressure tests will be conducted to estimate vertical and horizontal air permeabilities at different levels. In addition, permeabilities will be calculated from atmospheric breathing data that will include evaluation of subsurface response to barometric pressure fluctuations. Computer simulations suggest that air from the surface can move several meters into the ground during typical barometric pressure cycles (Massmann and Farrier, 1992). Gas ports will be installed at different depths in two boreholes to evaluate atmospheric pumping. The results of this study will provide valuable information on subsurface gas transport processes and the various techniques to obtain data on parameters required for simulation of such processes. These data will be required for performance assessment calculations.Bureau of Economic Geolog

Kecacingan Usus Pada Anak Sekolah Dasar Di Tanawangko Kecamatan Tombariri Kabupaten Minahasa

: Helminth is one of the most commonly infected parasites in human. According to WHO, more than 1,5 billions of people around the world are infected by helminthes. The highest number of helminthiasis cases is of school age children. This study was aimed to obtain the helminthiasis cases in students of elementary schools at Tanawangko Minahasa and to identify the types of helmiths. This was a descriptive study. Feces samples from the students were kept in feces pot and then were examined microscopically. The results showed that of the 118 feces samples there were five samples (4.3%) which were positively infected by helminth, Ascaris lumbricoides

Entropy and equilibrium state of free market models

Many recent models of trade dynamics use the simple idea of wealth exchanges among economic agents in order to obtain a stable or equilibrium distribution of wealth among the agents. In particular, a plain analogy compares the wealth in a society with the energy in a physical system, and the trade between agents to the energy exchange between molecules during collisions. In physical systems, the energy exchange among molecules leads to a state of equipartition of the energy and to an equilibrium situation where the entropy is a maximum. On the other hand, in the majority of exchange models, the system converges to a very unequal condensed state, where one or a few agents concentrate all the wealth of the society while the wide majority of agents shares zero or almost zero fraction of the wealth. So, in those economic systems a minimum entropy state is attained. We propose here an analytical model where we investigate the effects of a particular class of economic exchanges that minimize the entropy. By solving the model we discuss the conditions that can drive the system to a state of minimum entropy, as well as the mechanisms to recover a kind of equipartition of wealth

A Xenon Condenser with a Remote Liquid Storage Vessel

We describe the design and operation of a system for xenon liquefaction in which the condenser is separated from the liquid storage vessel. The condenser is cooled by a pulse tube cryocooler, while the vessel is cooled only by the liquid xenon itself. This arrangement facilitates liquid particle detector research by allowing easy access to the upper and lower flanges of the vessel. We find that an external xenon gas pump is useful for increasing the rate at which cooling power is delivered to the vessel, and we present measurements of the power and efficiency of the apparatus.Comment: 22 pages, 7 figures Corrected typos in authors lis

Design and Performance of the XENON10 Dark Matter Experiment

XENON10 is the first two-phase xenon time projection chamber (TPC) developed within the XENON dark matter search program. The TPC, with an active liquid xenon (LXe) mass of about 14 kg, was installed at the Gran Sasso underground laboratory (LNGS) in Italy, and operated for more than one year, with excellent stability and performance. Results from a dark matter search with XENON10 have been published elsewhere. In this paper, we summarize the design and performance of the detector and its subsystems, based on calibration data using sources of gamma-rays and neutrons as well as background and Monte Carlo simulations data. The results on the detector's energy threshold, energy and position resolution, and overall efficiency show a performance that exceeds design specifications, in view of the very low energy threshold achieved (<10 keVr) and the excellent energy resolution achieved by combining the ionization and scintillation signals, detected simultaneously

Yard-Sale exchange on networks: Wealth sharing and wealth appropriation

Yard-Sale (YS) is a stochastic multiplicative wealth-exchange model with two phases: a stable one where wealth is shared, and an unstable one where wealth condenses onto one agent. YS is here studied numerically on 1d rings, 2d square lattices, and random graphs with variable average coordination, comparing its properties with those in mean field (MF). Equilibrium properties in the stable phase are almost unaffected by the introduction of a network. Measurement of decorrelation times in the stable phase allow us to determine the critical interface with very good precision, and it turns out to be the same, for all networks analyzed, as the one that can be analytically derived in MF. In the unstable phase, on the other hand, dynamical as well as asymptotic properties are strongly network-dependent. Wealth no longer condenses on a single agent, as in MF, but onto an extensive set of agents, the properties of which depend on the network. Connections with previous studies of coalescence of immobile reactants are discussed, and their analytic predictions are successfully compared with our numerical results.Comment: 10 pages, 7 figures. Submitted to JSTA

The Cosmology of Composite Inelastic Dark Matter

Composite dark matter is a natural setting for implementing inelastic dark matter - the O(100 keV) mass splitting arises from spin-spin interactions of constituent fermions. In models where the constituents are charged under an axial U(1) gauge symmetry that also couples to the Standard Model quarks, dark matter scatters inelastically off Standard Model nuclei and can explain the DAMA/LIBRA annual modulation signal. This article describes the early Universe cosmology of a minimal implementation of a composite inelastic dark matter model where the dark matter is a meson composed of a light and a heavy quark. The synthesis of the constituent quarks into dark mesons and baryons results in several qualitatively different configurations of the resulting dark matter hadrons depending on the relative mass scales in the system.Comment: 31 pages, 4 figures; references added, typos correcte

Liquid Xenon Detectors for Positron Emission Tomography

PET is a functional imaging technique based on detection of annihilation photons following beta decay producing positrons. In this paper, we present the concept of a new PET system for preclinical applications consisting of a ring of twelve time projection chambers filled with liquid xenon viewed by avalanche photodiodes. Simultaneous measurement of ionization charge and scintillation light leads to a significant improvement to spatial resolution, image quality, and sensitivity. Simulated performance shows that an energy resolution of <10% (FWHM) and a sensitivity of 15% are achievable. First tests with a prototype TPC indicate position resolution <1 mm (FWHM).Comment: Paper presented at the International Nuclear Physics Conference, Vancouver, Canada, 201

Basic kinetic wealth-exchange models: common features and open problems

We review the basic kinetic wealth-exchange models of Angle [J. Angle, Social Forces 65 (1986) 293; J. Math. Sociol. 26 (2002) 217], Bennati [E. Bennati, Rivista Internazionale di Scienze Economiche e Commerciali 35 (1988) 735], Chakraborti and Chakrabarti [A. Chakraborti, B. K. Chakrabarti, Eur. Phys. J. B 17 (2000) 167], and of Dragulescu and Yakovenko [A. Dragulescu, V. M. Yakovenko, Eur. Phys. J. B 17 (2000) 723]. Analytical fitting forms for the equilibrium wealth distributions are proposed. The influence of heterogeneity is investigated, the appearance of the fat tail in the wealth distribution and the relaxation to equilibrium are discussed. A unified reformulation of the models considered is suggested.Comment: Updated version; 9 pages, 5 figures, 2 table