THE STRUCTURE, PERFORMANCE, AND SUSTAINABILITY OF AGRICULTURE IN THE MOUNTAIN REGION

Farmers in the Mountain Region-in both metro and nonmetro areas-face growth in population and nonfarm employment that affects land use and how farmers operate their businesses. Even in remote locations, people moving to amenity areas may result in farmers changing their operations. Sustainable agriculture, already practiced by Mountain Region farmers to some extent, may help farming to continue. Nonfarm people also have an interest in the continuation of agriculture and the adaptation of sustainable practices, in order to help preserve the amenities that make the region attractive to migrants. Growth in the region does provide some benefits to farmers, however. Growth can help keep the value of farmland up through nonfarm demand for land. In addition, the greater availability of jobs means that off-farm work is available to households operating farms. Off-farm work is particularly important, given the concentrated distribution of farm income.Production Economics,

Oil Supply and Tax Incentive

macroeconomics, oil, tax incentive

Recent Changes in Farm Structure: A Canada-U.S. Comparison

Following a series of bilateral and multilateral agreements, the past two decades have seen increased trade and investment liberalization between Canada and the United States in the agri-food sector. Changes in trade policy are one of several paths by which farm structure can change. This increased liberalization, together with the largest drop in Canadian farm numbers recorded by the Census of Agriculture in thirty years, has provided the impetus to review some aspects of farm structure. In particular, this article presents the latest Canadian and U.S. data on the number of farms by sales class, the concentration of sales and other production-related variables, and the distribution of income and receipts. We explore whether significant changes in the latter two elements of farm structure have occurred during this period of trade and investment liberalization.Crop Production/Industries, Farm Management, International Relations/Trade,

Examples of Nonisothermal Moisture Movement in Wood

Moisture content gradients in wood samples subjected to nonisothermal conditions were monitored over time in two separate experiments using sample material from 1) green ash and 2) southern yellow pine. The warm and cold environment temperatures were maintained at 80 F and -40 F for both experiments. The warm environment relative humidity was maintained at 40% during the ash experiment, and 70% during the southern yellow pine experiment. The cold environment relative humidity was not controlled, but was presumed to be nearly 100%. The temperature gradient through the samples was measured using embedded Type-T thermocouples, and the moisture content profile from the warm to cold surface was determined by sectioning sample material.Total average moisture content generally increased as a function of time, indicating that moisture flux into the sample through the warm surface was greater than flux out of the sample at the cold surface. Moisture accumulated toward the warm surface for the southern yellow pine, but was generally more evenly distributed through the depth for the ash samples. These differences were attributed to different warm environment relative humidity conditions maintained between the two experiments

Moisture Adsorption and Transport by Wood Due to a Thermal Gradient Caused by Air-to-Air Thermal Differences

An experiment was conducted in which a thermal gradient was established in wood by air-to-air temperature differences. A walnut board and a redwood board, each 3/4 inch thick and approximately 4 inches wide, were installed in a 1-inch-thick sheet of wood fiber insulation board employed as the lid of a chest-type freezer. The narrow edges of the boards were exposed to room air and freezer air, respectively. The MC profiles were periodically determined by removing cross sections from the boards and reducing them to thin slices. Moisture moved down the temperature gradient and against the concentration gradient. The average MC of the walnut and redwood boards increased 21% and 2%, respectively, during the 53-day test. The results showed that when wood is used as a thermal barrier, water vapor will enter the wood from the warm air and can be condensed in the wood if the necessary temperature profile exists. In certain applications of wood, this raises the possibility for free water accumulation in wood and the associated hazards. Moisture movement down a temperature gradient in wood is hypothesized to be a causative factor in the ceiling/partition separation problem with trusses in residential housing

Large-signal modelling and analysis of switching regulators

A large-signal switching regulator model is derived, and prominent features of the transient response are determined. In particular, analytical expressions are found for the equilibrium points of the system which yield insight into the large-signal response, and computer-generated transient waveforms are obtained. As an example, a boost regulator is investigated, and is found to be stable for small signals but unstable for large transients

Rips Complexes of Planar Point Sets

Fix a finite set of points in Euclidean $n$-space \euc^n, thought of as a point-cloud sampling of a certain domain D\subset\euc^n. The Rips complex is a combinatorial simplicial complex based on proximity of neighbors that serves as an easily-computed but high-dimensional approximation to the homotopy type of $D$. There is a natural ``shadow'' projection map from the Rips complex to \euc^n that has as its image a more accurate $n$-dimensional approximation to the homotopy type of $D$. We demonstrate that this projection map is 1-connected for the planar case $n=2$. That is, for planar domains, the Rips complex accurately captures connectivity and fundamental group data. This implies that the fundamental group of a Rips complex for a planar point set is a free group. We show that, in contrast, introducing even a small amount of uncertainty in proximity detection leads to `quasi'-Rips complexes with nearly arbitrary fundamental groups. This topological noise can be mitigated by examining a pair of quasi-Rips complexes and using ideas from persistent topology. Finally, we show that the projection map does not preserve higher-order topological data for planar sets, nor does it preserve fundamental group data for point sets in dimension larger than three.Comment: 16 pages, 8 figure

International Space Station United States Orbital Segment Oxygen Generation System On-Orbit Operational Experience

The International Space Station (ISS) United States Orbital Segment (USOS) Oxygen Generation System (OGS) was originally intended to be installed in ISS Node 3. The OGS rack delivery was accelerated, and it was launched to ISS in July of 2006 and installed in the US Laboratory Module. Various modification kits were installed to provide its interfaces, and the OGS was first activated in July of 2007 for 15 hours, In October of 2007 it was again activated for 76 hours with varied production rates and day/night cycling. Operational time in each instance was limited by the quantity of feedwater in a Payload Water Reservoir (PWR) bag. Feedwater will be provided by PWR bag until the USOS Water Recovery System (WRS) is delivered to SS in fall of 2008. This paper will discuss operating experience and characteristics of the OGS, as well as operational issues and their resolution

Norepinephrine-induced acute renal failure: A reversible ischemic model of acute renal failure

Several studies have shown that acute renal failure (ARF) can be produced in the dog by infusing norepinephrine (NE) into a renal artery [1, 2]. In these studies the injury appeared to be confined to the infused kidney, with no changes occurring in systemic hemodynamics or in the function of the contralateral kidney. The hemodynamic changes noted in the infused kidney were comparable to those seen in human ARF. A major criticism of these studies, however, is that the renal failure was not shown to be reversible, as it typically is in man. In the present study, we have reexamined the NE-induced model of ARF in the dog with the particular purpose of finding a set condition which would cause ARF and yet allow recovery of renal function within a period of time comparable to that usually seen in the human disease