Pulsatile spiral blood flow through arterial stenosis

Pulsatile spiral blood flow in a modelled three-dimensional arterial stenosis, with a 75% cross-sectional area reduction, is investigated by using numerical fluid dynamics. Two-equation k-ω model is used for the simulation of the transitional flow with Reynolds numbers 500 and 1000. It is found that the spiral component increases the static pressure in the vessel during the deceleration phase of the flow pulse. In addition, the spiral component reduces the turbulence intensity and wall shear stress found in the post-stenosis region of the vessel in the early stages of the flow pulse. Hence, the findings agree with the results of Stonebridge et al. (2004). In addition, the results of the effects of a spiral component on time-varying flow are presented and discussed along with the relevant pathological issues

Migration and the Environment: The Case of Philippine Uplands

Modeling the relationship between population growth and migration, this paper shows that destinations with higher average household incomes attract many immigrants. While it is not different from previous studies, this paper utilizes more environmentally based measures of economic opportunity at the destination.natural resources and environment, forestry sector, environmental issues, migration

Migration and the Environment: The Case of Philippine Uplands

Modeling the relationship between population growth and migration, this paper shows that destinations with higher average household incomes attract many immigrants. While it is not different from previous studies, this paper utilizes more environmentally based measures of economic opportunity at the destination.natural resources and environment, forestry sector, environmental issues, migration

Forest Charges and Trusts: Shared Benefits with Clear Responsibilities

This paper examines the Community-Based Forest Management Program (CBFM) and Industrial Forest Management Agreements (IFMA) within the context of efficient forest management. Investigation on ways of accomplishing the objectives of the agency, community and commercial forestry in decreased costs is conducted. Results show a need for DENR’s redirection of financial and human resources to focus on critical environmental tasks. Focus on higher-value timber opportunities can increase the potential for sustainable management and increase in the government revenue collection.forestry sector, rent and fee

Forest Charges and Trusts: Shared Benefits with Clear Responsibilities

This paper examines the Community-Based Forest Management Program (CBFM) and Industrial Forest Management Agreements (IFMA) within the context of efficient forest management. Investigation on ways of accomplishing the objectives of the agency, community and commercial forestry in decreased costs is conducted. Results show a need for DENR’s redirection of financial and human resources to focus on critical environmental tasks. Focus on higher-value timber opportunities can increase the potential for sustainable management and increase in the government revenue collection.forestry sector, rent and fee

Determination of material properties in the Chaboche unified viscoplasticity model

An experimental programme of cyclic mechanical testing of a 316 stainless steel, at temperatures up to 600°C, under isothermal conditions, for the identification of material constitutive constants, has been carried out using a thermo-mechanical fatigue (TMF) test machine with induction coil heating. The constitutive model adopted is a modified Chaboche unified viscoplasticity model, which can deal with both cyclic effects, such as combined isotropic and kinematic hardening, and rate-dependent effects, associated with viscoplasticity. The characterization of 316 stainless steel is presented and compared with results from cyclic isothermal tests. A least-squares optimization algorithm has been developed and implemented for determining the material constants in order to further improve the general fit of the model to experimental data, using the initially obtained material constants as the starting point in this optimization process. The model predictions using both the initial and optimized material constants are compared to experimental data

Nonlinear Ionic Conductivity of Thin Solid Electrolyte Samples: Comparison between Theory and Experiment

Nonlinear conductivity effects are studied experimentally and theoretically for thin samples of disordered ionic conductors. Following previous work in this field the {\it experimental nonlinear conductivity} of sodium ion conducting glasses is analyzed in terms of apparent hopping distances. Values up to 43 \AA are obtained. Due to higher-order harmonic current density detection, any undesired effects arising from Joule heating can be excluded. Additionally, the influence of temperature and sample thickness on the nonlinearity is explored. From the {\it theoretical side} the nonlinear conductivity in a disordered hopping model is analyzed numerically. For the 1D case the nonlinearity can be even handled analytically. Surprisingly, for this model the apparent hopping distance scales with the system size. This result shows that in general the nonlinear conductivity cannot be interpreted in terms of apparent hopping distances. Possible extensions of the model are discussed.Comment: 7 pages, 6 figure

Determination of Potentially Arable Land and Measurements of Non-Agricultural Uses for Nine Selected Areas in Africa

The purpose of this study was to determine the percentage of total potentially arable land currently committed to non-agricultural human settlement uses in selected African agro-climatic zones. Nine study areas equal in size to Landsat scenes, were selected by climatic zones as specified by the Food and Agriculture Organization, Rome, Italy. Soils information were fundamental to this project and were combined with climatic and crop suitability information for each study area. This information was manually converted to digital form for input to a computer-aided geographic information system, thereby creating nine independent data bases. Landsat CCT data for these study areas were processed by computer to identify and map the extent of human settlement. These data were automatically input as files into the appropriate data bases using the registration and aggregation program LEVI, developed at the Holcomb Research Institute. Potentially arable lands were identified within each Landsat scene, using FA0 criteria, based upon soil and crop suitability within each climatic zone. Landsat digital data identified the extent and location of human settlement, and file manipulation techniques identified settlements occurring upon these potentially arable lands. The results of this study indicate that the amount of potentially arable land varied dramatically between the nine study areas, ranging from 778 km² in South Africa (.19% committed to human settlements) to 29,017 km² in Nigeria (2.l% committed to human settlement). The research described in this paper was supported by the Food and Agriculture Organization of the United Nations under contract No. UNFPA/INT/75/P13-2/AGL

M\u3csup\u3e2\u3c/sup\u3e Factor of a Vector Schell-Model Beam

Extending existing scalar Schell-model source work, we derive the M2 factor for a general electromagnetic or vector Schell-model source to assess beam quality. In particular, we compute the M2 factors for two vector Schell-model sources found in the literature. We then describe how to synthesize vector Schell-model beams in terms of specified, desired M2 and present Monte Carlo simulation results to validate our analysis