Massive Dirac fermions and the zero field quantum Hall effect

Through an explicit calculation for a Lagrangian in quantum electrodynamics in (2+1)-space--time dimensions (QED$_3$), making use of the relativistic Kubo formula, we demonstrate that the filling factor accompanying the quantized electrical conductivity for massive Dirac fermions of a single species in two spatial dimensions is a half (in natural units) when time reversal and parity symmetries of the Lagrangian are explicitly broken by the fermion mass term. We then discuss the most general form of the QED$_3$ Lagrangian, both for irreducible and reducible representations of the Dirac matrices in the plane, with emphasis on the appearance of a Chern-Simons term. We also identify the value of the filling factor with a zero field quantum Hall effect (QHE).Comment: 15 pages. Accepted in Jour. Phys.

In the shadow of segregation : women's identity in the modern Iraqi house

Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Architecture, 1994.Includes bibliographical references (p. 103-107).This thesis intends to develop a critical perspective on the culture and politics of the modern house in Iraq. It advances the discussion from the authoritative religious environment of women's segregation in the Islamic era associated with the courtyard house, to the seemingly liberated status of women in modern times, as manifested in the design of the house. The primary argument is that there was little substantial change in this status through British Colonialism and the emergence of the secular state and modern aesthetics in Post-Colonial Iraq. Marking the pre-modern period from the Abbasid to the Ottoman rule, the traditional courtyard house reflected the apparent agreement between the world view of a traditional society and the accepted status of women in it. This house manifested principles of spatial hierarchy and privacy as a response to the deeply-embedded principles of social hierarchization of sexes and prevailing assumptions about women. Thus the courtyard house came to be "the house of women's segregation" par excellance. In the British colonial era, the upper-middle classes manifested their preference for the Classical architecture of the colonizers and for European lifestyles; however, the selective process and adaptation of the influences of Colonial architecture into house design made the logic behind the design principles inconsistent. The inflexibility of these principles with respect to accommodating concepts of women's privacy, such as principles of axis and symmetry, reveals the inappropriateness of this style to work within the cultural conventions. In the period of post-colonial independence and nation building, the aspirations of the Iraqi architects for a new aesthetic revolution and a social reform was articulated with the state revolutionary politics. Seemingly divorced from traditional methods of building and traditional materials, the architects promoted aspects of modern utopia and positivism in anticipation of an environmentally and socially better world. The architects' intellectual passion for abstraction and their excessive infatuation with technology, culminating in the new aesthetic and openness, were applied primarily in facade treatment and minor details rather than the actual plan of the house. Thus the plan was still confined to the conventional practices of the society based on imperatives of privacy and hierarchy. Moreover, the new aesthetic of openness conflicted with the entrenched social norms and with woman's perception of herself, resulting in a feeling of alienation. The promise of women's liberation was illusive within the limited definition of the politics of that liberation and given the persistent perception of women in society as dependent and vulnerable. The modern house could not carry a new social reform with its new aesthetic. It still faced the dilemma of society marked by the conflict between the desired definition of progressiveness and the existing conventions of identity, thereby revealing the emptiness and the unresolved contradiction between aspirations and actual practice.by Raya H. Ani.M.S

Effects of a Sedentary vs. Active Lifestyle on Blood Glucose Uptake

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Feature Selection and Classification of MAQC-II Breast Cancer and Multiple Myeloma Microarray Gene Expression Data

Microarray data has a high dimension of variables but available datasets usually have only a small number of samples, thereby making the study of such datasets interesting and challenging. In the task of analyzing microarray data for the purpose of, e.g., predicting gene-disease association, feature selection is very important because it provides a way to handle the high dimensionality by exploiting information redundancy induced by associations among genetic markers. Judicious feature selection in microarray data analysis can result in significant reduction of cost while maintaining or improving the classification or prediction accuracy of learning machines that are employed to sort out the datasets. In this paper, we propose a gene selection method called Recursive Feature Addition (RFA), which combines supervised learning and statistical similarity measures. We compare our method with the following gene selection methods

Dynamic changes in lung microRNA profiles during the development of pulmonary hypertension due to chronic hypoxia and monocrotaline

<b>Objective</b>: MicroRNAs (miRNAs) are small noncoding RNAs that have the capacity to control protein production through binding "seed" sequences within a target mRNA. Each miRNA is capable of potentially controlling hundreds of genes. The regulation of miRNAs in the lung during the development of pulmonary arterial hypertension (PAH) is unknown.<p></p> <b>Methods and Results</b>: We screened lung miRNA profiles in a longitudinal and crossover design during the development of PAH caused by chronic hypoxia or monocrotaline in rats. We identified reduced expression of Dicer, involved in miRNA processing, during the onset of PAH after hypoxia. MiR-22, miR-30, and let-7f were downregulated, whereas miR-322 and miR-451 were upregulated significantly during the development of PAH in both models. Differences were observed between monocrotaline and chronic hypoxia. For example, miR-21 and let-7a were significantly reduced only in monocrotaline-treated rats. MiRNAs that were significantly regulated were validated by quantitative polymerase chain reaction. By using in vitro studies, we demonstrated that hypoxia and growth factors implicated in PAH induced similar changes in miRNA expression. Furthermore, we confirmed miR-21 downregulation in human lung tissue and serum from patients with idiopathic PAH.<p></p> <b>Conclusion</b>: Defined miRNAs are regulated during the development of PAH in rats. Therefore, miRNAs may contribute to the pathogenesis of PAH and represent a novel opportunity for therapeutic intervention.<p></p&gt

Effects of a Six-Month Walking Intervention on the Physical Activity Measures Among Older Adults

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Changes in Balance Measures During a Pedometer-Based Senior Citizen Walking Program

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Circular strings, wormholes and minimum size

The quantization of circular strings in an anti-de Sitter background spacetime is performed, obtaining a discrete spectrum for the string mass. A comparison with a four-dimensional homogeneous and isotropic spacetime coupled to a conformal scalar field shows that the string radius and the scale factor have the same classical solutions and that the quantum theories of these two models are formally equivalent. However, the physically relevant observables of these two systems have different spectra, although they are related to each other by a specific one-to-one transformation. We finally obtain a discrete spectrum for the spacetime size of both systems, which presents a nonvanishing lower bound.Comment: 11 pages, LaTeX2e, minor change

Effect of a Walking Program on Functional Fitness Measures in Older Adults

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Comparing Short Physical Performance Battery Results in Active vs. Non-Active Geriatric Individuals

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