11,307 research outputs found
Deformations of generalized complex branes
We investigate the formal deformation theory of (rank 1) branes on
generalized complex (GC) manifolds. This generalizes, for example, the
deformation theory of a complex submanifold in a fixed complex manifold. For
each GC brane on a GC manifold , we construct a
formal (pointed) groupoid (defined
over a certain category of real Artin algebras) that encodes the formal
deformations of . We study the geometric content of this groupoid
in a number of different situations. Using the theory of (bi)semicosimplicial
differential graded Lie algebras (DGLAs), we construct for each brane
a DGLA that governs the "locally trivializable"
deformations of . As a concrete application of this construction,
we prove an unobstructedness result
A microprocessor-based one dimensional optical data processor for spatial frequency analysis
A high degree of accuracy was obtained in measuring the spatial frequency spectrum of known samples using an optical data processor based on a microprocessor, which reliably collected intensity versus angle data. Stray light control, system alignment, and angle measurement problems were addressed and solved. The capabilities of the instrument were extended by the addition of appropriate optics to allow the use of different wavelengths of laser radiation and by increasing the travel limits of the rotating arm to + or - 160 degrees. The acquisition, storage, and plotting of data by the computer permits the researcher a free hand in data manipulation such as subtracting background scattering from a diffraction pattern. Tests conducted to verify the operation of the processor using a 25 mm diameter pinhole, a 39.37 line pairs per mm series of multiple slits, and a microscope slide coated with 1.091 mm diameter polystyrene latex spheres are described
Rationing Antiretroviral Therapy for HIV/AIDS in Africa: Efficiency, Equity, and Reality
Background: Rationing of access to antiretroviral therapy already exists in sub-Saharan Africa and will intensify as national treatment programs develop. The number of people who are medically eligible for therapy will far exceed the human, infrastructural, and financial resources available, making rationing of public treatment services inevitable.
Methods: We identified 15 criteria by which antiretroviral therapy could be rationed in African countries and analyzed the resulting rationing systems across 5 domains: clinical effectiveness, implementation feasibility, cost, economic efficiency, and social equity.
Findings: Rationing can be explicit or implicit. Access to treatment can be explicitly targeted to priority subpopulations such as mothers of newborns, skilled workers, students, or poor people. Explicit conditions can also be set that cause differential access, such as residence in a designated geographic area, co-payment, access to testing, or a demonstrated commitment to adhere to therapy. Implicit rationing on the basis of first-come, first-served or queuing will arise when no explicit system is enforced; implicit systems almost always allow a high degree of queue-jumping by the elite. There is a direct tradeoff between economic efficiency and social equity.
Interpretation: Rationing is inevitable in most countries for some period of time. Without deliberate social policy decisions, implicit rationing systems that are neither efficient nor equitable will prevail. Governments that make deliberate choices, and then explain and defend those choices to their constituencies, are more likely to achieve a socially desirable outcome from the large investments now being made than are those that allow queuing and queue-jumping to dominate
Carbon thin film thermometry
The work concerning carbon thin film thermometry is reported. Optimum film deposition parameters were sought on an empirical basis for maximum stability of the films. One hundred films were fabricated for use at the Marshall Space Flight Center; 10 of these films were given a precise quasi-continuous calibration of temperature vs. resistance with 22 intervals between 5 and 80 K using primary platinum and germanium thermometers. Sensitivity curves were established and the remaining 90 films were given a three point calibration and fitted to the established sensitivity curves. Hydrogen gas-liquid discrimination set points are given for each film
The unification bonus (malus) in postwall Eastern Germany
This paper presents estimates of the unification bonus for East Germans over the period 1991 to 1998. The unification bonus is defined as the discounted value of the difference between a person?s actual income and his or her counterfactual real income stream forecast for a hypothetical continuation of economic life in a static GDR. The two main issues tackled in this study are the construction of valid deflators for a comparison of real incomes during the transition from a centralized to a market economy and the estimation of plausible counterfactual income streams. Our central result is that 19 percent of East Germans received a present value malus and so can be regarded as unification losers but that the aggregate bonus is ten times the size of the aggregate malus of the sample. --Real income comparison,income distribution and mobility,economies in transition
Financial Inclusion and Natural Disasters
This dissertation explores the implications of natural disaster risk for access to financial services, especially credit. Its results show that disasters can dramatically undermine the ability of financial intermediaries (FIs) to lend after an event, increasing the cost of the disaster and delaying recovery. Moreover, the risk of natural disasters discourages investment in vulnerable regions and economic sectors and so slows economic development. Financial risk transfer mechanisms such as insurance can help maintain lending following an event. While many international development projects have targeted disaster insurance markets to households, managing disaster-related credit risk may be done more effectively through insurance products for FIs. Additionally, prudential supervision and the credit risk rating methods of investors in developing and emerging economies are dominated by developed country standards that overlook natural disaster risks. Public and private interests align in the need to tailor such standards and so enhance the effectiveness with which vulnerable FIs manage disaster risk
Hydrographic Survey Systems for the 1980's : A Technological Forecast
Increasing numbers of engineers and scientists are forecasting developments for the future. These anticipated technological developments have hydrographic survey applications. Technological forecasting provides alternatives that may be selected for development, utilizing new technology to reduce costs and improve products. The forecasts facilitate communication and cooperation among those engaged in survey system planning and allocation of funds, ships, men and equipment. Engineers and scientists who are aware of future system requirements can prepare for them. Knowledge of alternatives enables decision makers to choose what sort of hydrographic survey systems they wish to design and build. Expanding technology will be shaped by those who are willing to improve, promote, develop, and try new concepts
The Histological Effects of Tapazole on Rat Thyroids, Hearts, and Adrenals
The anti-thyroid drug Tapazole, when fed to white rats at the dietary level of 0.1% Tapazole in finely ground laboratory meal, produces changes in body weight, thyroid weight and in the histological composition of the thyroid. Histological examination shows that the affected thyroids have undergone hypertrophy and hyperplasia. Tapazole does not seem to affect rat hearts or adrenals
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