517 research outputs found

    Interferometric detection of dispersed shock waves in small scale diaphragm-less shock tube of 1mm diameter

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    We have developed a small scale shock tube of 1mm diameter which has a diaphragm-less driver section. The experiment is performed by using our small scale shock tube, where the propagation velocities of the shock waves are measured with a specially designed laser interferometer under several pressure conditions. Helium and CO2 are used as the driver and test gas, respectively. As the results show, we have succeeded in observing weak shock waves in a shock tube of 1mm diameter. The fully or partly dispersed shock waves, which are attributed to the exitation of the vibrational energy of CO2, are also observed at the weak shock region

    Southwestern Minnesota Farm Business Management Association 2008 Annual Report

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    Average net farm income was 190,901in2008forthe99farmsincludedinthisannualreportoftheSouthwesternMinnesotaFarmBusinessManagementAssociation.Averageearningsdecreasedby21190,901 in 2008 for the 99 farms included in this annual report of the Southwestern Minnesota Farm Business Management Association. Average earnings decreased by 21% from the average of 242,267 in 2007 (Figure 1). 2008 ended a steady trend of increasing year-to-year incomes for these farms from 2001 to 2007. Crop farms, with historically high corn and soybean prices, remained very profitable. However, specialized hog farms, which had been very profitable for the past four years, experienced substantial losses. Highlights of association financial results for 2008: Median net farm income was 178,874,slightlylowerthantheaverage,indicatingthattheaveragewasincreasedbyhighprofitsofthemostprofitablefarms.Thiseffectwasnotaslargeaspreviousyears,likelybecauseoflossesbylargerhogoperations.Thedifferencebetweenthemostprofitablefarmsandtheleastprofitablecontinuedtoincrease.Themostprofitable20178,874, slightly lower than the average, indicating that the average was increased by high profits of the most profitable farms. This effect was not as large as previous years, likely because of losses by larger hog operations. • The difference between the most profitable farms and the least profitable continued to increase. The most profitable 20% of the farms earned an average net farm income of 449,997 while the least profitable lost 29,476.Averagegrosscashincomeincreasedby20-29,476. • Average gross cash income increased by 20% while expenses increased 22% for the average farm. Most of the reduction in income resulted from a lower value of inventory changes. Inventories did increase in value, but not by as much as in 2007. • Government payments accounted for 2% of gross cash farm income (Figure 2). Crop sales accounted for 50% of income while livestock sales were 42%. • Average rate of return on assets (ROA) was 11% with assets valued at adjusted cost or book value, down from 17% in 2007 (Figure 3). Rate of return on equity (ROE) averaged 15%, down from 25 percent. The fact that ROE exceeded ROA indicates that debt capital earned more than its cost. • The average farm generated net worth growth of 115,999. The average debt-to-asset ratio improved slightly to 39%, down from 40% (Figure 4). • Corn yields were up but soybean yields were down. Corn averaged 172 bushels per acre compared to 162 in 2007. Soybeans yields decreased to 44 bushels from 49 in 2007 (Figure 5). • Both corn and soybean prices received increased by over 50% to 4.51forcornand4.51 for corn and 10.83 for soybeans. • The cost to raise an acre of corn (with land rent) increased by 23% while soybean costs increased by 21%. The cost to produce a bushel of corn on cash rented land increased from 2.58perbushelin2007to2.58 per bushel in 2007 to 2.90 in 2008, while soybean costs per bushel increased from 6.14to6.14 to 7.21. • The average specialized hog operation (those with 70% of sales from hogs or pigs) lost over 150,000in2008(Figure6).Allotherfarmtypeswithenoughfarmstoreportaveragednetincomesveryclosetotheassociationaverage.Basedonrateofreturnonassets,cropfarms(thosewith70150,000 in 2008 (Figure 6). All other farm types with enough farms to report averaged net incomes very close to the association average. • Based on rate of return on assets, crop farms (those with 70% of sales from crops) were the most profitable type of farm in 2008, with an ROA of 14.7% (Figure 7). All other farm types were profitable except specialized hog farms, which earned a -2.2% ROA. • Hog farms, after large losses in 2008, replaced Crop/Beef farms as the type of farm group with the highest debt to asset ratio at the end of the year (Figure 8). • The largest farms, those with gross revenue over 1,000,000, were the least profitable based on rate of return on assets. This group earned an average ROA of 7% compared to 14% for farms that grossed between 500,000and500,000 and 1,000,000. • With exceptionally high feed prices, no hog or beef enterprise, with the exception of contract growing of hogs (where the contractor provided the feed) covered even direct costs of production. The report provides additional information on profitability, liquidity, and solvency as well as other whole-farm information and detailed information on crop and livestock enterprises. Also reported are whole-farm financial condition and performance by county, sales size class, type of farm, debt-to-asset ratio, and age of operator.Agricultural Finance, Farm Management,

    Effects of Policies Designed to Keep Firearms from High-Risk Individuals

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    This article summarizes and critiques available evidence from studies published between 1999 and August 2014 on the effects of policies designed to keep firearms from high-risk individuals in the United States. Some prohibitions for high-risk individuals (e.g., those under domestic violence restraining orders, violent misdemeanants) and procedures for checking for more types of prohibiting conditions are associated with lower rates of violence. Certain laws intended to prevent prohibited persons from accessing firearms -- rigorous permit-to-purchase, comprehensive background checks, strong regulation and oversight of gun dealers, and requiring gun owners to promptly report lost or stolen firearms -- are negatively associated with the diversion of guns to criminals. Future research is needed to examine whether these laws curtail nonlethal gun violence and whether the effects of expanding prohibiting conditions for firearm possession are modified by the presence of policies to prevent diversion

    Selection of workers and firm heterogeneity

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    A model based on differences between workers regarding their preferences for wage and leisure drives the heterogeneity of firms result. The more industrious workers are driven to small firms due to free riding in large firms. An industry consisting of small and large firms turns out to produce more output than an industry consisting of only large firms. Some comparative statics results are derived with respect to the size of large firms, the productivity difference between firms, and monitoring capabilities

    Factors Affecting a Recently Purchased Handgun’s Risk for Use in Crime under Circumstances That Suggest Gun Trafficking

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    While many handguns are used in crime each year in the USA, most are not. We conducted this study to identify factors present at the time of a handgun’s most recent retail sale that were associated with its subsequent use in crime under circumstances suggesting that the handgun had been trafficked—purchased with the intent of diverting it to criminal use. Handguns acquired in multiple-gun purchases were of particular interest. Using data for 180,321 handguns purchased from federally licensed retailers in California in 1996, we studied attributes of the handguns, the retailers selling them, the purchasers, and the sales transactions. Our outcome measure was a handgun’s recovery by a police agency, followed by a gun ownership trace, conducted by the Bureau of Alcohol, Tobacco, Firearms and Explosives, that determined (a) that the recovery had occurred within 3 years of the handgun’s most recent purchase from a licensed retailer and (b) that the person who possessed the gun when it was recovered by police was not its most recent purchaser. Altogether, 722 handguns were recovered and had trace results that met the additional criteria. Handguns acquired in multiple-gun, same-day transactions were more likely to be traced than were single-purchase handguns (odds ratio [OR] 1.33, 95% confidence intervals [CI] 1.08 to 1.63). This was not the case for multiple-purchase handguns defined more broadly as multiple handguns purchased by one individual over any 30-day period as used in “one-gun-a-month” laws. Bivariate regressions indicated increased risk of a handgun being traced when it sold new for $150 or less (OR 4.28, 95% CI 3.59 to 5.11) or had been purchased by a woman (OR 2.02, 95% CI 1.62 to 2.52). Handguns sold by retailers who also had a relatively high proportion (≥2%) of purchases denied because the prospective purchasers were prohibited from owning firearms were more likely to be traced than were those sold by other retailers (OR 4.09, 95% CI 3.39 to 4.94). These findings persisted in multivariate analyses. Our findings suggest specific strategies for intervention to prevent gun violence

    Plant trait and vegetation data along a 1314 m elevation gradient with fire history in Puna grasslands, Per\ufa

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    \ua9 2024. The Author(s). Alpine grassland vegetation supports globally important biodiversity and ecosystems that are increasingly threatened by climate warming and other environmental changes. Trait-based approaches can support understanding of vegetation responses to global change drivers and consequences for ecosystem functioning. In six sites along a 1314 m elevational gradient in Puna grasslands in the Peruvian Andes, we collected datasets on vascular plant composition, plant functional traits, biomass, ecosystem fluxes, and climate data over three years. The data were collected in the wet and dry season and from plots with different fire histories. We selected traits associated with plant resource use, growth, and life history strategies (leaf area, leaf dry/wet mass, leaf thickness, specific leaf area, leaf dry matter content, leaf C, N, P content, C and N isotopes). The trait dataset contains 3,665 plant records from 145 taxa, 54,036 trait measurements (increasing the trait data coverage of the regional flora by 420%) covering 14 traits and 121 plant taxa (ca. 40% of which have no previous publicly available trait data) across 33 families
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