Tulane University

About: Tulane University is a education organization based out in New Orleans, Louisiana, United States. It is known for research contribution in the topics: Population & Blood pressure. The organization has 24478 authors who have published 47205 publications receiving 1944993 citations. The organization is also known as: University of Louisiana.

Locally adaptive metric nearest-neighbor classification

Abstract: Nearest-neighbor classification assumes locally constant class conditional probabilities. This assumption becomes invalid in high dimensions with finite samples due to the curse of dimensionality. Severe bias can be introduced under these conditions when using the nearest-neighbor rule. We propose a locally adaptive nearest-neighbor classification method to try to minimize bias. We use a chi-squared distance analysis to compute a flexible metric for producing neighborhoods that are highly adaptive to query locations. Neighborhoods are elongated along less relevant feature dimensions and constricted along most influential ones. As a result, the class conditional probabilities are smoother in the modified neighborhoods, whereby better classification performance can be achieved. The efficacy of our method is validated and compared against other techniques using both simulated and real-world data.

An evaluation of variables influencing implant fixation by direct bone apposition.

Abstract: A systematic mechanical and histologic evaluation of design variables affecting bone apposition to various biocompatible materials was undertaken. The variables investigated included material elastic modulus, material surface texture, as well as material surface composition. The implant materials included polymethylmethacrylate (PMMA), low-temperature isotropic (LTI) pyrolytic carbon, commercially pure (C.P.) titanium, and aluminum oxide (Al2O3). Implant surface texture was varied by either polishing or grit-blasting the various materials. Implant surface composition was varied by applying a coating of ultra-low temperature isotropic (ULTI) pyrolytic carbon to the various implants. A total of 12 types of implants were evaluated in vivo by placement transcortically in the femora of adult mongrel dogs for a period of 32 weeks. Following sacrifice, mechanical push-out testing was performed to determine interface shear strength and interface shear stiffness. The results obtained from mechanical testing indicate that for implants fixed by direct bone apposition, interface stiffness and interface shear strength are not significantly affected by either implant elastic modulus or implant surface composition. Varying surface texture, however, significantly affected the interface response to the implants. For each elastic modulus group the roughened surfaced implants exhibited greater strengths than the corresponding smooth surfaced implants. Undecalcified histologic evaluation of the implants demonstrated that the roughened implants exhibited direct bone apposition, whereas the smooth implants exhibited various degrees of fibrous tissue encasement. Thus, for implants utilizing direct bone apposition fixation, it appears that of the parameters investigated, implant surface texture is the most significant.

Creating Liquidity out of Spatial Fixity: The Secondary Circuit of Capital and the Subprime Mortgage Crisis

Abstract: Since the classic work of Henri Lefebvre and David Harvey, the ‘secondary circuit of capital’ has been a focal point for debate among critical urban scholars. Against the background of contemporary debates on financialization, this article investigates the institutional and political roots of the subprime mortgage crisis. Empirically, the article situates the current turmoil of the US mortgage sector with reference to a series of ad hoc legal and regulatory actions taken since the 1980s to promote the securitization of mortgages and expand the secondary mortgage market. Securitization is a process of converting illiquid assets into transparent securities and is a critical component of the financialization of real estate markets and investment. Specifically, I examine the crucial role played by the US Treasury Department's Office of the Comptroller of the Currency (OCC) and the Department of Housing and Urban Development (HUD) in creating the polices and legal-regulatory conditions that have nurtured the growth of a market for securitizing subprime loans. Theoretically, the article examines the subprime mortgage crisis as an illustration of the contradictions of capital circulation as expressed in the tendency of capital to annihilate space through time. Resume Depuis les travaux de reference d’Henri Lefebvre et de David Harvey, le ‘circuit secondaire des capitaux’ a suscite de nombreuses discussions entre specialistes critiques de la ville. Avec en toile de fond les debats contemporains sur la financiarisation, cet article etudie les racines institutionnelles et politiques de la crise des subprimes . Sur le plan empirique, il situe le bouleversement actuel du secteur americain des prets hypothecaires par rapport a une serie de mesures de Droit et de reglementations specifiques adoptees depuis les annees 1980 pour promouvoir la titrisation et le marche secondaire des credits hypothecaires. La titrisation, qui permet de convertir des actifs peu liquides en valeurs mobilieres transparentes, est une composante essentielle de la financiarisation de l’investissement et des marches immobiliers. Une attention particuliere est accordee au role crucial qu’ont joue, aux Etats-Unis, l’autorite de surveillance des banques relevant du ministere des Finances (OCC), ainsi que le ministere du Logement et de l’Urbanisme (HUD), dans la creation des cadres et des conditions juridico-reglementaires qui ont nourri l’essor du marche de la titrisation des prets hypothecaires a risque. Sur le plan theorique, l’article analyse la crise des subprimes comme une illustration des contractions de la circulation des capitaux, ces derniers tendant a aneantir l’espace par le temps.

Causal effects of the early caregiving environment on development of stress response systems in children.

Abstract: Disruptions in stress response system functioning are thought to be a central mechanism by which exposure to adverse early-life environments influences human development. Although early-life adversity results in hyperreactivity of the sympathetic nervous system (SNS) and hypothalamic–pituitary–adrenal (HPA) axis in rodents, evidence from human studies is inconsistent. We present results from the Bucharest Early Intervention Project examining whether randomized placement into a family caregiving environment alters development of the autonomic nervous system and HPA axis in children exposed to early-life deprivation associated with institutional rearing. Electrocardiogram, impedance cardiograph, and neuroendocrine data were collected during laboratory-based challenge tasks from children (mean age = 12.9 y) raised in deprived institutional settings in Romania randomized to a high-quality foster care intervention (n = 48) or to remain in care as usual (n = 43) and a sample of typically developing Romanian children (n = 47). Children who remained in institutional care exhibited significantly blunted SNS and HPA axis responses to psychosocial stress compared with children randomized to foster care, whose stress responses approximated those of typically developing children. Intervention effects were evident for cortisol and parasympathetic nervous system reactivity only among children placed in foster care before age 24 and 18 months, respectively, providing experimental evidence of a sensitive period in humans during which the environment is particularly likely to alter stress response system development. We provide evidence for a causal link between the early caregiving environment and stress response system reactivity in humans with effects that differ markedly from those observed in rodent models.