The economic geography of trade, production and income : a survey of empirics.

This paper surveys the empirical literature on the economic geography of trade flows, factor prices, and the location of production. The discussion is structured around the empirical predictions of a canonical theoretical model. We review empirical evidence on the determinants of trade costs and the effects of these costs on trade flows. Geography is a major determinant of factor prices, and access to foreign markets alone is shown to explain some 35% of the cross-country variation in per capita income. The paper documents empirical findings of home market (or magnification) effects, suggesting that imperfectly competitive industries are drawn more than proportionately to locations with good market access. Sub-national evidence establishes the presence of industrial clustering, and we examine the roles played by product market linkages to customer and supplier firms, knowledge spillovers, and labour market externalities.

Position-dependent diffusion of light in disordered waveguides

Diffusion has been widely used to describe a random walk of particles or waves, and it requires only one parameter -- the diffusion constant. For waves, however, diffusion is an approximation that disregards the possibility of interference. Anderson localization, which manifests itself through a vanishing diffusion coefficient in an infinite system, originates from constructive interference of waves traveling in loop trajectories -- pairs of time-reversed paths returning to the same point. In an open system of finite size, the return probability through such paths is reduced, particularly near the boundary where waves may escape. Based on this argument, the self-consistent theory of localization and the supersymmetric field theory predict that the diffusion coefficient varies spatially inside the system. A direct experimental observation of this effect is a challenge because it requires monitoring wave transport inside the system. Here, we fabricate two-dimensional photonic random media and probe position-dependent diffusion inside the sample from the third dimension. By varying the geometry of the system or the dissipation which also limits the size of loop trajectories, we are able to control the renormalization of the diffusion coefficient. This work shows the possibility of manipulating diffusion via the interplay of localization and dissipation.Comment: 24 pages, 6 figure

Campylomma (Mullein Plant Bug)

The campylomma bug (or mullein plant bug; Hemiptera: Miridae) causes sporadic damage in Utah apple orchards. Damage is inflicted by nymphs, which feed on developing fruit causing dimpling and fruit distortion. As apple fruits mature, they become less susceptible to campylomma injury. Injury appears shortly after petal fall as small corky areas alone or small corky areas surrounded by a depression. Golden Delicious is typically more susceptible to damage than Red Delicious. Pear fruit rarely suffer damage, even at high campylomma populations. Campylomma overwinter as eggs laid in the young twigs of apple, pear and other rosaceous plants. These eggs begin hatching in the spring at about pink stage of apple bud development. This insect has three to four generations per year. A portion of first generation adults migrate from orchard trees to herbaceous weeds, particularly common mullein. However, campylomma can be found in apple and pear orchards throughout the growing season. Late nymphal stages and adults are beneficial predators of aphids, mites and pear psylla. In late summer through fall, adults will migrate into orchards to lay overwintering eggs

Feedback controlled optics with wavefront compensation

The sensitivity model of a complex optical system obtained by linear ray tracing is used to compute a control gain matrix by imposing the mathematical condition for minimizing the total wavefront error at the optical system's exit pupil. The most recent deformations or error states of the controlled segments or optical surfaces of the system are then assembled as an error vector, and the error vector is transformed by the control gain matrix to produce the exact control variables which will minimize the total wavefront error at the exit pupil of the optical system. These exact control variables are then applied to the actuators controlling the various optical surfaces in the system causing the immediate reduction in total wavefront error observed at the exit pupil of the optical system

A Win-Win: Utilizing Human Services Students to Run a Campus Food Pantry

Abstract Recent studies have examined the growing problem of food insecurity among college students in the United States. In recent reports, as many as 30% of all college students are food insecure (CUFBA, 2020). It is imperative that college campuses address this issue, as many students are forced to leave college without completion in order to address financial concerns (Johnson, 2009). Over the last decade, campus-based food pantries have emerged as one means of addressing growing food insecurity among students. However, colleges and universities are facing budget cutbacks and other funding restrictions, creating greater challenges for meeting the needs of financially-struggling students. This article addresses how developing campus food pantries utilizing service-learning, internships and field practicum courses in Human Services programs can assist with addressing this need. By using Human Services students, as well as partnering with local agencies, colleges and universities can address the need for labor and supplies with few to no available state resources, providing a win-win situation for students and colleges

Stormcloud

https://digitalcommons.library.umaine.edu/mmb-vp/6318/thumbnail.jp

MIUS integration and subsystems test program

The MIUS Integration and Subsystems Test (MIST) facility at the Lyndon B. Johnson Space Center was completed and ready in May 1974 for conducting specific tests in direct support of the Modular Integrated Utility System (MIUS). A series of subsystems and integrated tests was conducted since that time, culminating in a series of 24-hour dynamic tests to further demonstrate the capabilities of the MIUS Program concepts to meet typical utility load profiles for a residential area. Results of the MIST Program are presented which achieved demonstrated plant thermal efficiencies ranging from 57 to 65 percent

Spatial, seasonal and climatic predicitve models of Rift Valley Fever disease across Africa

Understanding the emergence and subsequent spread of human infectious diseases is a critical global challenge, especially for high-impact zoonotic and vector-borne diseases. Global climate and land-use change are likely to alter host and vector distributions, but understanding the impact of these changes on the burden of infectious diseases is difficult. Here, we use a Bayesian spatial model to investigate environmental drivers of one of the most important diseases in Africa, Rift Valley fever (RVF). The model uses a hierarchical approach to determine how environmental drivers vary both spatially and seasonally, and incorporates the effects of key climatic oscillations, to produce a continental risk map of RVF in livestock (as a proxy for human RVF risk). We find RVF risk has a distinct seasonal spatial pattern influenced by climatic variation, with the majority of cases occurring in South Africa and Kenya in the first half of an El Niño year. Irrigation, rainfall and human population density were the main drivers of RVF cases, independent of seasonal, climatic or spatial variation. By accounting more subtly for the patterns in RVF data, we better determine the importance of underlying environmental drivers, and also make space- and time-sensitive predictions to better direct future surveillance resources. This article is part of the themed issue ‘One Health for a changing world: zoonoses, ecosystems and human well-being’