Room-temperature InAs0.89Sb0.11 photodetectors for CO detection at 4.6 mu m. .

An InAs0.89Sb0.11 photovoltaic detector that operates at room temperature in the 2.5-5 mu m mid-infrared wavelength region is reported. The photodiode has an extended spectral response compared with other currently available III-V room-temperature detectors. In order to accommodate the large lattice mismatch between the InAs0.89Sb0.11 active region and the InAs substrate, a buffer layer with an intermediate composition was introduced into the structure. In this way, we obtained room-temperature photodiodes with a cutoff wavelength near 5 mu m, a peak responsivity of 0.8 A/W, and a detectivity of 1.26 x 10(9) cm Hz(1/2)/W. These devices could be effectively used as the basis of an optical sensor for the environmental monitoring of carbon monoxide at 4.6 mu m, or as a replacement for PbSe photoconductors. (C) 2000 American Institute of Physics. [S0003-6951(00)02332-9]

Mid-infrared optoelectronics materials and devices International Conference — 1996, Lancaster University, UK

AbstractMid-infrared optoelectronics is now a rapidly expanding research area with many wide ranging applications. This international conference, which is the first of its kind, provides a unique opportunity for the exchange of information on new developments in semiconductor physics, growth technology, characterisation and applications of different materials & devices for the mid-infrared wavelength region

Shining a Light on \u3ci\u3eRattley\u3c/i\u3e: The Troublesome Diligent Search Standard Undercutting New York\u27s Freedom of Information Law

New York’s Freedom of Information Law (FOIL) provides citizens with access to the documents, statistics, and information relied on by New York State government agencies. Modeled after the federal Freedom of Information Act (FOIA), New York legislators designed the state’s “sunshine law” to promote transparency and accountability through a presumption of disclosure by requiring agencies to make all records available to the public except those specifically exempted by statute. But state agencies often rely on a separate, unceremonious reason to deny FOIL requests—they cannot find the documents. FOIL requires an agency to certify that it performed a diligent records search to justify such a denial, but a 2001 holding by the New York Court of Appeals in Rattley v. New York City Police Department permits agencies to properly deny a request in this manner without describing the search or offering a statement from the individual who personally performed the search. Despite FOIL’s promise of transparency and disclosure, an agency’s ability to deny a records request under Rattley without explaining its search efforts leaves requesters without their requested records and without meaningful recourse to challenge the agency’s alleged search in court. This Note argues that the Rattley standard used in New York state courts renders FOIL’s diligent search requirement entirely toothless, creates an inequitable burden-shifting framework for the agency and the requester, and contradicts FOIL’s original legislative intent to promote disclosure. This Note further argues that the New York Court of Appeals should replace Rattley with the federal courts’ reasonableness test and suggests a legislative fix to resolve FOIL’s statutory ambiguity regarding the diligent search certification requirement

Ignition and combustion of lunar propellants

The ignition and combustion of Al, Mg, and Al/Mg alloy particles in 99 percent O2/1 percent N2 mixtures is investigated at high temperatures and pressures for rocket engine applications. The 20 micron particles contain 0, 5, 10, 20, 40, 60, 80, and 100 weight percent Mg alloyed with Al, and are ignited in oxygen using the reflected shock in a shock tube near the endwall. Using this technique, the ignition delay and combustion times of the particles are measured at temperatures up to 3250 K as a function of Mg content for oxygen pressures of 8.5, 17, and 34 atm. An ignition model is developed which employs a simple lumped capacitance energy equation and temperature and pressure dependent particle and gas properties. Good agreement is achieved between the measured and predicted trends in the ignition delay times. For the particles investigated, the contribution of heterogeneous reaction to the heating of the particle is found to be significant at lower temperatures, but may be neglected as gas temperatures above 3000 K. As little as 10 percent Mg reduces the ignition delay time substantially at all pressures tested. The particle ignition delay times decrease with increasing Mg content, and this reduction becomes less pronounced as oxidizer temperature and pressure are increased

Electronic structure and magnetism of equiatomic FeN

In order to investigate the phase stability of equiatomic FeN compounds and the structure-dependent magnetic properties, the electronic structure and total energy of FeN with NaCl, ZnS and CsCl structures and various magnetic configurations are calculated using the first-principles TB-LMTO-ASA method. Among all the FeN phases considered, the antiferromagnetic NaCl structure with q=(00pi) is found to have the lowest energy at the theoretical equilibrium volume. However, the FM NaCl phase lies only 1mRyd higher. The estimated equilibrium lattice constant for nonmagnetic ZnS-type FeN agrees quite well with the experimental value, but for the AFM NaCl phase the estimated value is 6.7% smaller than that observed experimentally. For ZnS-type FeN, metastable magnetic states are found for volumes larger than the equilibrium value. On the basis of an analysis of the atom- and orbital-projected density of states and orbital-projected Crystal Orbital Hamilton Population, the iron-nitrogen interactions in NM ZnS, AFM NaCl and FM CsCl structures are discussed. The leading Fe-N interactions is due to the d-p iron-nitrogen hybridization, while considerable s-p and p-p hybridizations are also observed in all three phases. The iron magnetic moment in FeN is found to be highly sensitive to the nearest-neighboring Fe-N distance. In particular, the magnetic moment shows an abrupt drop from a value of about 2 muB to zero with the reduction of the Fe-N distance for the ZnS and CsCl structures.Comment: 12 pages, 6 figure

Uncoupling the Law of Takings

The following article is based on Deterrence and Distribution in the Law of Takings, 112 Harvard Law Review 997-1025 (March 1999), © 1999 by the Harvard Law Review Association, and appears here by permission. A complete version, with citations, is available from the authors or the editor of Law Quadrangle Notes. The law of takings couples together matters that should be treated independently. Whatever the boundaries of the the Takings Clause, we think there is much to be gained by analyzing takings in terms of the clause\u27s underlying purposes, and by understanding that efficiency and justice are best served by uncoupling matters and methods of deterrence from matters and methods of distribution

On Rereading Klaus Theweleit\u27s Male Fantasies

Klaus Theweleit\u27s Male Fantasies has generated broad interest in the literature of several academic disciplines. His analysis of the symbolic and gender dynamics of the leaders of the German Freikorps (German paramilitary mercenary units of the period 1918-1923) has been widely generalized into a theory of modern masculinity. Two issues inadequately explored in Theweleit\u27s work nonetheless must be read through more recent empirical and theoretical work in history and sociology: (1) the formative role of colonial military experience in the careers of the German Freikorps officers who provide the material for his analysis and (2) the complex historical problem of the facticity of rape in Freikorps activity

Room temperature midinfrared electroluminescence from GaInAsSbP light emitting diodes. .

Room temperature electroluminescence in the midinfrared near 4 µm is reported from GaInAsSbP light emitting diodes grown on GaSb by liquid phase epitaxy. Comparison of the electro- and photoluminescence revealed that light is generated on the p side of the diode. The energy shift (24 meV) is consistent with band gap narrowing and recombination via band tail states due to the Zn doping (1×1018 cm−3) in the p layer of the structure. The temperature dependent behavior of the luminescence and the improved emission intensity was attributed to recombination from localized states arising from electrostatic potential fluctuations due to compositional inhomogeneities in these alloys

Advances in Feature Selection with Mutual Information

The selection of features that are relevant for a prediction or classification problem is an important problem in many domains involving high-dimensional data. Selecting features helps fighting the curse of dimensionality, improving the performances of prediction or classification methods, and interpreting the application. In a nonlinear context, the mutual information is widely used as relevance criterion for features and sets of features. Nevertheless, it suffers from at least three major limitations: mutual information estimators depend on smoothing parameters, there is no theoretically justified stopping criterion in the feature selection greedy procedure, and the estimation itself suffers from the curse of dimensionality. This chapter shows how to deal with these problems. The two first ones are addressed by using resampling techniques that provide a statistical basis to select the estimator parameters and to stop the search procedure. The third one is addressed by modifying the mutual information criterion into a measure of how features are complementary (and not only informative) for the problem at hand