Critique [of Self-Evaluation of Black and White College Students by Keith D. Parker]

The article by Keith D. Parker raises interesting theoretical and methodological questions, but this review focuses on the latter. The author is correct in his critical assessment of black self-esteem research (BSER) methodology. Projective measures have been used in most cases and questions have been raised regarding the validity of such self-esteem measures and therefore about the believability of BSER findings.[1] In addition, blacks and whites tested have not been representative of the general black or white communities of the United States, yet inferences to and comparisons of the populations have been made. Finally, studies have employed non-multivariate statistical techniques which have prevented the use of controls

[Review of] Martin S. Jankowski. City Bound: Urban Life and Political Attitudes Among Chicano Youth

This work ranks as one of the most significant analyses of urban Chicano political socialization to date. Unlike contemporaries who are either theoreticians or numbers crunchers, Jankowski undertakes a quantitative analysis that is theoretically based. Hypotheses developed from three theories are tested to ascertain which best explains the political assimilation of Chicano adolescents in San Antonio, Albuquerque, and Los Angeles. The theories compared are: the Wirth/Chicago School which argues that the length of urban residence promotes assimilation; the neighborhood solidarity model which proposes that upward socioeconomic mobility and neighborhood integration promote assimilation; and the Marxist theory which argues that the political-economic structure of a socioeconomic system, i.e., society or city, determines modes of assimilation

[Review of] James Diego Vigil, From Indians to Chicanos: A Sociocultural History

Historians are typically satisfied with pinpointing dates and describing associated events while minimizing speculation and interpretations which cannot be directly supported with evidence. There is no question that this is a vital and popular methodological approach, and Chicano studies historians have usually complied with this norm--until now

[Review of] Pastora San Juan Cafferty and William C. McCready. Hispanics in the United States: A New Social Agenda

The editors of this book, associate professors at the University of Chicago, state that their work seeks to promote understanding of and raise questions about Hispanic social issues in the hope that a collective social agenda can result

Transcriptome comparison of resistant and suscentible Hevea brasiliensis cultivars infected by Microcyclus ulei

- Background and Aims South American Leaf Blight (SALB) is caused by an ascomycota, Microcyclus ulei (P. Henn.) v. Arx., and is the most damaging disease in Latin America and the most important threat for rubber tree plantations in Asia and Africa which produce 95% of the world rubber with susceptible genotypes. Because few information are available to understand the biological process of the disease development, suppression subtractive hybridization (SSH) approach was developed in order to identify genes differentially expressed at different stages of the pathogenic interaction with Microcyclus ulei, with a particular interest for defence and stress-related genes. - Methods To identify candidate genes and gain better understanding of the hostpathogen interaction in the pathosystem Hevea brasiliensis - Microcyclus ulei, Suppression Subtractive Hybridization libraries were compared. Leaflets of the MDF 180 partially resistant cultivar and the PB314 susceptible cultivar were inoculated with M. ulei. Using 6 to 72 h.p.i, 4 to 28 d.p.i, and 34 to 58 d.p.i infected and healthy leaflets, five cDNA libraries, highly enriched for M. ulei - induced genes were prepared. - Key Results Within 8027 clones randomly picked and sequenced from the libraries, 1165 singlets and 458 contigs for a total of 1623 non-redundant sequences were obtained. The redundancy of each SSH libraries were variable, ranging from 87% in PB314 4-28 d.p.i libary to 23% in MDF180 4-28 d.p.i library. Sequence analysis allowed the assignment of a putative functional category for 38% of sequences, whereas 15% of sequences corresponded to unknown function and 47% did not show any significant similarity with other proteins present in the databank. Clustering of the whole sequence reveal a high degree of dissimilarity between the genes isolated in each library. Moreover, the obtained ESTs compared with the Hevea latex transcriptome, appear highly specific of the leaf tissue. The comparison of the five libraries displayed a drastic diminution of the number of over-expressed genes in PB314 genotype during the infection process, differently from MDF180 genotype for which the number of genes related to stress and defence display an increase of 56%. These preliminary results are put together with symptomatic and histological observations. (Résumé d'auteur

Automatic near real-time selection of flood water levels from high resolution Synthetic Aperture Radar images for assimilation into hydraulic models: a case study

Flood extents caused by fluvial floods in urban and rural areas may be predicted by hydraulic models. Assimilation may be used to correct the model state and improve the estimates of the model parameters or external forcing. One common observation assimilated is the water level at various points along the modelled reach. Distributed water levels may be estimated indirectly along the flood extents in Synthetic Aperture Radar (SAR) images by intersecting the extents with the floodplain topography. It is necessary to select a subset of levels for assimilation because adjacent levels along the flood extent will be strongly correlated. A method for selecting such a subset automatically and in near real-time is described, which would allow the SAR water levels to be used in a forecasting model. The method first selects candidate waterline points in flooded rural areas having low slope. The waterline levels and positions are corrected for the effects of double reflections between the water surface and emergent vegetation at the flood edge. Waterline points are also selected in flooded urban areas away from radar shadow and layover caused by buildings, with levels similar to those in adjacent rural areas. The resulting points are thinned to reduce spatial autocorrelation using a top-down clustering approach. The method was developed using a TerraSAR-X image from a particular case study involving urban and rural flooding. The waterline points extracted proved to be spatially uncorrelated, with levels reasonably similar to those determined manually from aerial photographs, and in good agreement with those of nearby gauges

Constructing 3D crystal templates for photonic band gap materials using holographic optical tweezers

A simple and robust method is presented for the construction of 3-dimensional crystals from silica and polystyrene microspheres. The crystals are suitable for use as templates in the production of three-dimensional photonic band gap (PBG) materials. Manipulation of the microspheres was achieved using a dynamic holographic assembler (DHA) consisting of computer controlled holographic optical tweezers. Attachment of the microspheres was achieved by adjusting their colloidal interactions during assembly. The method is demonstrated by constructing a variety of 3-dimensional crystals using spheres ranging in size from 3 µm down to 800 nm. A major advantage of the technique is that it may be used to build structures that cannot be made using self-assembly. This is illustrated through the construction of crystals in which line defects have been deliberately included, and by building simple cubic structures

Optical absorption spectra in SrCu_2O_3 two-leg spin ladder

We calculate the phonon-assisted optical-absorption spectra in SrCu_2O_3 two-leg spin-ladder systems. The results for two models proposed for SrCu_2O_3 are compared. In the model including the effects of a cyclic four-spin interaction, the shoulder structure appears at 978 cm^{-1} and the peak appears at 1975 cm^{-1} in the spectrum for polarization of the electric field parallel to the legs. In the other model which describes a pure two-leg ladder, the peak appears around the lower edge of the spectrum at 1344 cm^{-1}. The feature can be effective in determining the proper model for SrCu_2O_3.Comment: 5 pages, 5 figures, to appear in PRB vol. 67 (2003

Correlation energies of inhomogeneous many-electron systems

We generalize the uniform-gas correlation energy formalism of Singwi, Tosi, Land and Sjolander to the case of an arbitrary inhomogeneous many-particle system. For jellium slabs of finite thickness with a self-consistent LDA groundstate Kohn-Sham potential as input, our numerical results for the correlation energy agree well with diffusion Monte Carlo results. For a helium atom we also obtain a good correlation energy.Comment: 4 pages,1 figur

Novel role for amphiregulin in protection from liver injury

Clinically, the Fas and Fas ligand system plays a central role in the development of hepatocyte apoptosis, a process contributing to a broad spectrum of liver diseases. Therefore, the development of therapies aimed at the inhibition of hepatocyte apoptosis is a major issue. Activation of the epidermal growth factor receptor has been shown to convey survival signals to the hepatocyte. To learn about the endogenous response of epidermal growth factor receptor ligands during Fas-mediated liver injury we investigated the expression of epidermal growth factor, transforming growth factor alpha, heparin-binding epidermal growth factor-like growth factor, betacellulin, epiregulin, and amphiregulin in the liver of mice challenged with Fas-agonist antibody. Amphiregulin expression, barely detectable in healthy liver, was significantly up-regulated. Amphiregulin administration abrogated Fas-mediated liver injury in mice and showed direct anti-apoptotic effects in primary hepatocytes. Amphiregulin activated the Akt and signal transducer and activator of transcription-3 survival pathways, and up-regulated Bcl-xL expression. Amphiregulin knock-out mice showed signs of chronic liver damage in the absence of any noxious treatment, and died faster than wild type mice in response to lethal doses of Fas-agonist antibody. In contrast, these mice were more resistant against sublethal liver damage, supporting the hypothesis that chronic liver injury can precondition hepatocytes inducing resistance to subsequent cell death. These results show that amphiregulin is a protective factor induced in response to liver damage and that it may be therapeutic in liver diseases