Attributes influencing self-employment propensity in urban and rural Sweden

Policies aiming at promoting entrepreneurship are in general formed on national levels, without any consideration of differences between urban and rural areas. Usually, cities are provided with better and more modern infrastructure; cities have better supply of physical, financial and human capital, and connected services, and cities have a more modern industrial structure in the sense that their shares of growing industry are higher. Thus, it is possible that policies for entrepreneurship, which in general are designed for urban areas, might be less effective when they are implemented in rural areas. A first step to test the validity of this hypothesis could be to investigate the differences between cities and countryside regarding self-employment propensity and factors affecting the choice to become self-employed. Based on an exceptionally rich data set containing very detailed socio-economic and geographical information on all residents in Sweden, this paper examines: (a) the scope and structure of self-employment propensity in urban and rural areas, respectively, in Sweden, divided into full-time and part-time self-employment, and (b) the importance of a number of attributes that may have an impact on individuals’ propensity to start an enterprise in the two area types. Variables being tested are connected to demography and education, labor market status, plant characteristics, self-employment experience, financial resources, family links and regional attributes. The main results indicate that self-employment entry is influenced by the same factors in the same way in urban and rural areas. However, countryside’s industrial structure has a smaller share of growing industries. The fact that countryside’s startups follow the existing industrial structure means that this “modernity gap” between densely built up areas and countryside remains. From a policy perspective, this must be seen as a serious problem for countryside’s growth potential. This gives an argument for designing a special entrepreneurship policy for the countryside in order to increase its share of growing trades and thereby modernize its industrial structure.     

An empirical examination of the location and timing of non-renewals in a farmland differential assessment program

We study the non-renewals of contracts in the farmland differential assessment program of California. An instrumental variable random-effect model for the location of non-renewals and a hazard model for the timing of non-renewals indicate that counties with high property tax rates have 0.8% lower odds of a non-renewal, transition slower to a rapid state of non-renewals by 4%, and transition faster to the slow state by 6%. This suggests differential assessment programs provide benefits to tax payers by preserving agricultural land and reducing how quickly development pressure causes non-renewals, and ultimately development, in farm communities. Counties at higher elevations transition faster to a rapid state of non-renewals by 4% and transition slower to the slow state by 2%. This suggests there should be more attention to development pressure at higher elevations, where regulations are weaker and amenities are greater.     

Investigation of solid particle number measurement: Existence and nature of sub-23 nm particles under PMP methodology

A Particle Measurement Program (PMP) compliant system, an AVL advanced particle counter (APC) and an alternative volatile particle removal system, a catalytic stripper (CS) were evaluated and compared for measuring solid particle number (PN) emissions. The evaluations and comparisons were conducted using sulfuric acid and hydrocarbon particles as model volatile particles in laboratory tests, and diluted exhaust from a diesel particle filter (DPF)-equipped heavy-duty diesel vehicle operated on a heavy-duty chassis dynamometer under steady speed conditions at two different engine loads. For the laboratory test, both the APC and CS removed more than 99% of the volatile particles in terms of PN when using aerosols composed of pure sulfuric acid or hydrocarbons. When using laboratory test aerosols consisting of mixtures of sulfuric acid and hydrocarbons more than 99% of the particles were removed by the APC but the surviving particles were no longer entirely volatile, 12–14% were solid. For the chassis dynamometer test, PN emissions between 3 and 10 nm downstream the APC were ∼2 and 7 times higher than the PN emissions of particles above 10 nm at the 74% and 26% engine load, respectively. At the 26% engine load, PN level of the 3–10 nm particles downstream the APC were significantly higher than that in the dilution tunnel, demonstrating that the APC was making 3–10 nm particles. The PN emission of 3–10 nm particles downstream the APC was related to the heating temperature of the APC evaporation tube, suggesting these particles are artifacts formed by renucleation of semivolatiles. Considerably fewer particles between 3 to 10 nm were seen downstream of the CS for both engine loads due mainly to removal of semivolatile material by the catalytic substrates, although some of this difference could be attributed to diffusion and thermophoretic losses. The findings of this study imply that improvement of the current PMP protocol would be necessary if the PMP were to be used in other applications where the PN emissions of particles below 23 nm are important.     

Cardiovascular concomitants in ultrasound production during cold exposure in infant rats.

Two experiments explored the cardiovascular consequences of extreme cold exposure and their relationship with ultrasound production in infant rats. Experiment 1 addressed the thermoregulatory and cardiovascular concomitants of ultrasound production during cold exposure in rats pretreated with saline or the ganglionic blocker chlorisondamine (5 mg/kg). For both groups, emission of ultrasound was associated with hypothermia and bradycardia. Experiment 2 explored whether the hypothermia experienced by pups in Experiment 1 is associated with increased blood viscosity, which is an important factor affecting venous return to the heart. Blood viscosity increased significantly as temperature decreased from 38°C to 22°C. These experiments suggest that, during extreme cold exposure, decreased cardiac output and increased blood viscosity combine to diminish venous return. The authors have hypothesized that pups respond to decreased return by recruiting the abdominal compression reaction, a physiological maneuver that propels blood back to the heart, resulting in emission of ultrasound as an acoustic by-product. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

高级实时频谱仪技术为雷达信号提供全新洞察力

雷达系统RF脉冲的瞬态特点给其测试带来了各种诊断挑战.为迎接这些挑战,实时频谱仪近二十年来一直提供独特的瞬态微波信号分析功能.通过提高DSP速度,最新的实时频谱仪不再受到这些限制.新一代实时频谱仪不仅为高级雷达诊断提供了频率覆盖范围、瞬时带宽和动态范围,还增加了多项对雷达专业人员尤为有用的新技术.本文考察了这些新技术及其它创新技术将如何改变传统雷达测试.     

Transparent, flexible, conductive carbon nanotube coatings for electrostatic charge mitigation

Low color, space environmentally durable polymeric films with sufficient electrical conductivity to mitigate electrostatic charge (ESC) build-up are needed for applications on advanced spacecraft, particularly on large, ultra-light weight space structures. For these applications, the films must exhibit electrical conductivity that can survive the folding and unfolding required for packaging and deployment. The work described herein consists of coating the surface of polymer films with a thin layer of single-walled carbon nanotubes (SWNTs). Surface resistivities in the range sufficient for ESC mitigation were achieved with minimal effects on the optical and thermo-optical properties of the films. Bending, folding or crumpling did not affect the surface resistivity of the coated films. The preparation and characterization of SWNT coated space durable polymer films are discussed.