Singular self-adjoint boundary value problems for systems of first order linear differential equations

M.S.Frank W. Stallar

Interactions in D-brane Configurations

We explore various interactions in D-brane configurations and their implications for the construction of phenomenologically viable string models. Initially, we investigate the scenario of parallel and perpendicular stacks of D-branes located on an orbifold singularity, as in the bottom-up construction. A supersymmetric D-brane model is presented, that has CP spontaneously broken by discrete torsion. The low energy physics is largely independent of the compactification scheme and the kahler metric has 'texture zeros’ dictated by the choice of discrete torsion. This motivates a simple ansatz for the kahler metric which results in a CKM matrix given in terms of two free parameters, hence we predict a single mixing angle and the CKM phase. The CKM phase is predicted to be close to /3.We then proceed to a discussion of a different class of models involving D-branes intersecting at arbitrary angles, and wrapping a compact internal space. Here we calculate tree level three and four point scattering amplitudes in type II string models with matter fields localised at D-brane intersections. We treat both the classical and quantum parts in detail, with the latter being computed using conformal field theory techniques developed for closed strings on orbifolds. Contributions from string states wrapping the internal space are also included. These calculations are then generalised to TV-point amplitudes, which are determined completely. Finally, we consider the application of these results to four fermion interactions. In particular, the implications for Higgs exchange in intersecting brane models is discussed

Sierra Club v. Public Service Company of Colorado: Judicial Amendment or towards Continuous Emission Compliance; Expanding the Scope of Citizen Suits and the 1990 Amendments to the Clean Air Act

In Sierra Club v. Public Service Company of Colorado, the United States District Court for the district of Colorado granted plaintiffs summary judgment motion, in part, finding emissions violations in excess of 19,000 times within a five year period. The court held that in a citizen action under the Clean Air Act (CAA), violations of opacity standards may be established through data and reports from a facility\u27s Continuous Emissions Monitoring Systems (CEMS). This holds true despite the fact that it is neither the applicable test method under the Environmental Protection Agency\u27s (EPA) regulations nor is it provided for in the CAA State Implementation Plan (SIP) provisions. Prior to 1990, emission violations could only be demonstrated through the applicable standards set forth in the EPA\u27s regulations or SIPs. However, with the recently enacted 1990 Amendments, the Colorado court reasoned that the CAA allows any evidence of a violation or compliance to be considered under the Federal Rules of Evidence (FRE), including, but not limited to, bypass and control equipment malfunctions and expert testimony, regardless of whether it is an applicable test method under the EPA\u27s regulations. This case note discusses whether the court\u27s ruling constituted a judicial amendment or a rational analysis of the applicable statutory and regulatory scheme. Part II provides a background of the CAA, air pollution standards, and state compliance. Part ill analyzes whether the defendants are likely to succeed on appeal to the United States Court of Appeals, the impact of its decision upon industry, and how citizen groups are likely to gain power from this decision. Part IV concludes that the EPA should adopt the proposed rules requiring CEMS or similar systems to be installed in all utility plants to measure emissions violations on a continuous basis. These proposed rules clarify the requirements necessary to meet Congressional intent in passing the 1990 amendments. The rule will provide citizen groups with easy access to information for monitoring purposes and will ensure greater compliance with emission standards

Paper cemeteries: informal barriers to Brazilian public security reform

How can we understand the role of the police in Brazil’s public security system?  In particular, have reforms initiated since the 1985 transition to democracy made the police more accountable to the public? This article addresses those questions. The next section describes the importance of public security as a political issue in Brazil. The article then examines the notion of accountability, and offers a justification of the use of case studies from Recife with which to explore the dilemmas of public security reform. In the following sections, the article analyses the impact of two new accountability mechanisms on policing in Recife – the police ombudsman and community councils. The article argues that so far, the operation of these mechanisms has been marked by informal barriers, barriers that have stymied the enhancement of police accountability to the public. The conclusion summarizes the argument

Road and bridge construction across gypsum karst in England

Gypsum karst problems in the Permian and Triassic sequences of England have caused difficult conditions for bridge and road construction. In Northern England, the Ripon Bypass crosses Permian strata affected by active gypsum karst and severe subsidence problems. Here, the initial borehole site investigation for the road was supplemented by resistivity tomography studies. The roadway was reinforced with two layers of tensile membrane material within the earth embankment. This will prevent dangerous catastrophic collapse, but will allow sagging to show where problems exist. The River Ure Bridge was constructed across an area of subsidence pipes filled with alluvial deposits. It was built with extra strength, larger than normal foundations. If one pier fails, the bridge is designed for adjacent arches to span the gap without collapse. The bridge piers are also fitted with electronic load monitoring to warn of failure. In the Midlands area of England, road construction over Triassic gypsum has required a phase of ground improvement on the Derby Southern Bypass. Here, the gypsum caps a hill where it was formerly mined; it dips through a karstic dissolution zone into an area of complete dissolution and collapse. The road and an associated flyover were built across these ground conditions. A major grouting program before the earthworks began treated the cavities in the mine workings and the cavernous margin of the gypsum mass. Within the karstic dissolution zone, gypsum blocks and cavities along the route were identified by conductivity and resistivity geophysical surveys, excavated and backfilled. In the areas of complete dissolution and collapse, the road foundation was strengthened with vibrated stone columns and a reinforced concrete road deck was used

Brain involvement in Duchenne muscular dystrophy: a role for dystrophin isoform Dp71 in cell migration and proliferation

Intelligence of individuals with Duchenne muscular dystrophy (DMD) is lower than the general population. Cognitive impairment, epilepsy, autism and attention deficit hyperactivity disorder are prevalent. Mounting evidence links these symptoms to the loss of dystrophin in the brain; yet central nervous system involvement in DMD has been largely ignored. The most predominant dystrophin isoform in the brain is the smaller Dp71 isoform expressed in neurons and glia. Distal DMD mutations affecting Dp71 expression are linked to cognitive impairment. The function(s) of Dp71 and how its absence can lead to cognitive and behavioural symptoms are not well understood. We are modelling the loss of Dp71 both endogenously in DMD patient-derived fibroblasts (which, in controls, naturally express Dp71) and with siRNA in neuronal and glial cell lines. Four patient fibroblast cell lines, each harbouring a different DMD gene mutation that naturally results in the loss of Dp71 are being studied. Accompanying clinical data confirms these patients display cognitive and/or behavioural symptoms, which is severe for two individuals. Our preliminary findings highlight a role for Dp71 in cell migration and proliferation; alterations in these processes are associated with psychiatric disorders prevalent in DMD such as autism. We will present would healing and proliferation assay data exploring these role(s) and discuss potential molecular mechanisms behind the cognitive and behavioural symptoms observed in DMD. The high risk of neuropsychiatric syndromes in Duchene warrants early intervention to achieve the best possible quality of life; our findings have significant potential to inform ongoing drug development in this area

Demonstration of Passive Fuel Cell Thermal Management Technology

The NASA Glenn Research Center is developing advanced passive thermal management technology to reduce the mass and improve the reliability of space fuel cell systems for the NASA Exploration program. The passive thermal management system relies on heat conduction within highly thermally conductive cooling plates to move the heat from the central portion of the cell stack out to the edges of the fuel cell stack. Using the passive approach eliminates the need for a coolant pump and other cooling loop components within the fuel cell system which reduces mass and improves overall system reliability. Previous development demonstrated the performance of suitable highly thermally conductive cooling plates and integrated heat exchanger technology to collect the heat from the cooling plates (Ref. 1). The next step in the development of this passive thermal approach was the demonstration of the control of the heat removal process and the demonstration of the passive thermal control technology in actual fuel cell stacks. Tests were run with a simulated fuel cell stack passive thermal management system outfitted with passive cooling plates, an integrated heat exchanger and two types of cooling flow control valves. The tests were run to demonstrate the controllability of the passive thermal control approach. Finally, successful demonstrations of passive thermal control technology were conducted with fuel cell stacks from two fuel cell stack vendors

A Pair of Compact Red Galaxies at Redshift 2.38, Immersed in a 100 kpc Scale Ly-alpha Nebula

We present Hubble Space Telescope (HST) and ground-based observations of a pair of galaxies at redshift 2.38, which are collectively known as 2142-4420 B1 (Francis et al. 1996). The two galaxies are both luminous extremely red objects (EROs), separated by 0.8 arcsec. They are embedded within a 100 kpc scale diffuse Ly-alpha nebula (or blob) of luminosity ~10^44 erg/s. The radial profiles and colors of both red objects are most naturally explained if they are young elliptical galaxies: the most distant yet found. It is not, however, possible to rule out a model in which they are abnormally compact, extremely dusty starbursting disk galaxies. If they are elliptical galaxies, their stellar populations have inferred masses of ~10^11 solar masses and ages of ~7x10^8 years. Both galaxies have color gradients: their centers are significantly bluer than their outer regions. The surface brightness of both galaxies is roughly an order of magnitude greater than would be predicted by the Kormendy relation. A chain of diffuse star formation extending 1 arcsec from the galaxies may be evidence that they are interacting or merging. The Ly-alpha nebula surrounding the galaxies shows apparent velocity substructure of amplitude ~ 700 km/s. We propose that the Ly-alpha emission from this nebula may be produced by fast shocks, powered either by a galactic superwind or by the release of gravitational potential energy.Comment: 33 pages, 9 figures, ApJ in press (to appear in Jun 10 issue