String Theory and Noncommutative Geometry

We extend earlier ideas about the appearance of noncommutative geometry in string theory with a nonzero B-field. We identify a limit in which the entire string dynamics is described by a minimally coupled (supersymmetric) gauge theory on a noncommutative space, and discuss the corrections away from this limit. Our analysis leads us to an equivalence between ordinary gauge fields and noncommutative gauge fields, which is realized by a change of variables that can be described explicitly. This change of variables is checked by comparing the ordinary Dirac-Born-Infeld theory with its noncommutative counterpart. We obtain a new perspective on noncommutative gauge theory on a torus, its T-duality, and Morita equivalence. We also discuss the D0/D4 system, the relation to M-theory in DLCQ, and a possible noncommutative version of the six-dimensional (2,0) theory.Comment: 100 pages, sorry. Clarifications added, trivial misprints fixed and references adde

Providing antiretroviral care in conflict settings.

There has been an historic expectation that delivering combination antiretroviral therapy (cART) to populations affected by violent conflict is untenable due to population movement and separation of drug supplies. There is now emerging evidence that cART provision can be successful in these populations. Using examples from Médecins Sans Frontières experience in a variety of African settings and also local nongovernmental organizations' experiences in northern Uganda, we examine novel approaches that have ensured retention in programs and adequate adherence. Emerging guidelines from United Nations bodies now support the expansion of cART in settings of conflict

Analyzing the Influence of a Swirl Brake on a Smooth Liquid Annular Seal Through Measuring Static and Rotordynamic Characteristics

Data are available for a previously tested annular seal with no swirl brakes (NSB). The NSB seal design was modified by adding slots at the inlet to produce a swirl brake (SB) seal. Tests were conducted to evaluate the static and dynamic characteristics of the modified SB seal. The SB data was then compared to the NSB data to understand how the seal rotordynamic coefficients are affected when swirl brakes are added. The SB and NSB seals had a radial clearance (Cr) of 203.2 um with the diameter of the seals (D) being 102 mm. The length to diameter ratio (L/D) of the NSB seal was 0.50, while the SB seal had an L/D of 0.45 due to the addition of swirl brakes. The SB seal was tested at three different inlet pre-swirl ratios (PSR): high preswirl, medium pre-swirl, and radial injection. During testing, operational conditions were varied by changing differential pressure (?P), running speed (w), and eccentricity ratio (e0). The test points were at w = 2, 4, 6, 8 krpm, ?P = 2.07, 4.14, 6.21, 8.27 bar and e0 = 0.00, 0.27, 0.53, 0.80. The test fluid was ISO VG 2 oil. The static data for SB showed that the flow rate (Q) increased as the imposed PSR increased, meaning the high pre-swirl case produced the highest Q values. Swirl brakes deliver the greatest reduction in PSR compared to that of NSB seals at high ?P, low w, and toward the centered position (e0=0.00). A vector Reynolds number was produced over the range of 1300 to 4400. The flow through the test stand was predicted to be transitional and turbulent

Discolorations in Southern Hardwood Logs: Biological and Non-biological Staining Control Practices

Discolorations in highly valued southern hardwood species have been a costly problem for the U.S. forest products industry since its beginning. Both microbial (fungi) and non-microbial (enzyme-mediated) sapstain problems are more prevalent in the southeast than in other regions, so preventive measure must be done to keep hardwood logs and lumber discolorationree. Six full-scale field trials were conducted along the Mississippi River from Yokena, MS to Ripley, TN between March to October 2007. The basis for the research was a belief that discolorations that affect southern hardwood logs can be controlled by various techniques such as log end coating, inventory management, and combinations of each. These tests revealed important information such as chemical compatibility issues, storage facility upkeep, workforce development through scheduling and communication, and other items were found in this research to keep southern hardwood logs and lumber from discoloring

The effects of cycling shoe outsole material on plantar stress.

The purpose of this investigation was to determine if cycling shoes made with stiff material cause an increase in peak plantar stress over shoes with less stiff material. Shoe stiffness measurements were collected under controlled conditions and in two different configurations using a dynamic hydraulic tensile testing machine. Measurements of plantar stress were taken while subjects pedaled in a seated position at a controlled power output of 400 Watts. Capacitive-based sensor insoles were placed in the shoes to measure the peak stress under each foot during pedaling. The shoes made with carbon fiber produced peak plantar stresses 18% higher than those of a more traditional plastic design (121.2 kPa vs. 103.0 kPa, p-value = 0.005). Carbon fiber shoes presented stiffness values 42% and 550% higher than plastic shoes in longitudinal bending and three-point bending, respectively