2,369 research outputs found
Surface Artifact Assemblage Variability: A Consideration of the Natural Factors Influencing Artifact Recovery
The purpose of this research was to examine the effects of naturally occurring variables on surface artifact recovery. This was accomplished by isolating and reviewing pertinent variables, which are rainfall and soil factors. Information from this review was incorporated into an experiment designed to measure the effects of rainfall on artifact exposure and recovery. The results from the surface recovery experiment were used to form baseline data that allowed meaningful interpretation of three additional plowzone data recovery exercises. These were (1) artifact detection by shovel test, (2) prediction of surface density from plowzone excavation data, and (3) reliability of surface collections as indicators of plowzone assemblage content.
Results of repeated collections following precipitation ranging from no rain to more than 11 cm demonstrated drastic increases in artifact densities, yet a recovery threshold was recognized past which more rainfall produced few additional artifacts. Small plowzone shovel tests (25 cm2) proved to be fairly good detectors of surface scatters as sparse as .10 artifacts/m2, and increasing test size to 50 cm2 allowed detection of scatters as sparse as .04/m2. Results of least squares model regression revealed that the relationship between the artifact density/m2 for a 5 m2 surface collection and the artifact density/liter excavated beneath it is a strong one. However, this relationship weakens with a decrease in excavated volume to a point where densities from a 25 cm2 test demonstrate very little association with surface density. Comparative analysis showed artifact size to be the primary difference between surface and plowzone assemblages. In instances where artifact type is size-dependent, assessments of total plowzone assemblages based on surface samples could be incorrect. It is stressed that integration of the surface recovery information produced by this study, with plowzone recovery techniques such as shovel-testing, will alleviate the problem of incompatibility of results derived from surface and subsurface data recovery techniques prevalent in regional archaeological survey
Of Turkey Tetrazzini and George Wallace Buttons: The Experiences of the First Cohort of Africanamericans to Attend a Newly Desegregated Law School
With these interviews I have tried to capture a very small slice of the social reality of ordinary African-Americans with regard to legal education at a formerly segregated, still overwhelmingly white, University, and their role in providing access to legal services to ordinary African-Americans in the first decades after desegregation. We know, given the grossly disproportionate number of African-American men whom our society incarcerates, in what amounts in my mind to a form of de facto slavery and reflects our society\u27s deep-seated paranoia about black men generally, that our legal system remains today, nearly fifty years after major civil rights legislation, deeply hostile to the interests of African-Americans as a class. It requires little imagination to infer the immeasurably greater hostility of a legal system under the control of overtly and unrepentantly racist judges and attorneys. William Randall, now a judge in Macon, Georgia, asserts that he knows of a situation in which a white attorney stated in open court, this nigger\u27s guilty, regarding an African-American criminal defendant whom he was supposedly representing. Blatant racism aside, this incident also manifestly involved an egregious failure of that attorney to abide by the most elementary principle of an attorney\u27s professional responsibility, to provide the most vigorous and effective possible representation to one\u27s client. Thus we see that, in addition to being inherently grossly immoral, racism also has the undesirable effect of undermining adherence to other, facially unrelated principles that we should hold dear
Treatment of estrogen-induced dermatitis with omalizumab
In 1945, Drs Bernhard Zondek and Yehuda Bromberg demonstrated intradermal treatment with estrone and estradiol benzoate induced urticarial lesions in some patients.1 Fifty years later, Shelley et al,2 who introduced the concept of progesterone dermatitis several decades prior, defined estrogen dermatitis based on studies of 7 women with premenstrual flares of skin eruptions including papulovesicular, urticarial, or eczematous lesions or generalized pruritus. Previously described therapies for estrogen dermatitis include estrogen desensitization, tamoxifen, leuprolide, and oophorectomy.3 Here we report a case of estrogen-induced dermatitis successfully treated with omalizumab
Genome wide signatures of positive selection: The comparison of independent samples and the identification of regions associated to traits
<p>Abstract</p> <p>Background</p> <p>The goal of genome wide analyses of polymorphisms is to achieve a better understanding of the link between genotype and phenotype. Part of that goal is to understand the selective forces that have operated on a population.</p> <p>Results</p> <p>In this study we compared the signals of selection, identified through population divergence in the Bovine HapMap project, to those found in an independent sample of cattle from Australia. Evidence for population differentiation across the genome, as measured by F<sub>ST</sub>, was highly correlated in the two data sets. Nevertheless, 40% of the variance in F<sub>ST </sub>between the two studies was attributed to the differences in breed composition. Seventy six percent of the variance in F<sub>ST </sub>was attributed to differences in SNP composition and density when the same breeds were compared. The difference between F<sub>ST </sub>of adjacent loci increased rapidly with the increase in distance between SNP, reaching an asymptote after 20 kb. Using 129 SNP that have highly divergent F<sub>ST </sub>values in both data sets, we identified 12 regions that had additive effects on the traits residual feed intake, beef yield or intramuscular fatness measured in the Australian sample. Four of these regions had effects on more than one trait. One of these regions includes the <it>R3HDM1 </it>gene, which is under selection in European humans.</p> <p>Conclusion</p> <p>Firstly, many different populations will be necessary for a full description of selective signatures across the genome, not just a small set of highly divergent populations. Secondly, it is necessary to use the same SNP when comparing the signatures of selection from one study to another. Thirdly, useful signatures of selection can be obtained where many of the groups have only minor genetic differences and may not be clearly separated in a principal component analysis. Fourthly, combining analyses of genome wide selection signatures and genome wide associations to traits helps to define the trait under selection or the population group in which the QTL is likely to be segregating. Finally, the F<sub>ST </sub>difference between adjacent loci suggests that 150,000 evenly spaced SNP will be required to study selective signatures in all parts of the bovine genome.</p
Genome wide signatures of positive selection: The comparison of independent samples and the identification of regions associated to traits
The goal of genome wide analyses of polymorphisms is to achieve a better understanding of the link between genotype and phenotype. Part of that goal is to understand the selective forces that have operated on a population
Optoelectronic analysis of multijunction wire array solar cells
Wire arrays have demonstrated promising photovoltaic performance as single junction solar cells and are well suited to defect mitigation in heteroepitaxy. These attributes can combine in tandem wire array solar cells, potentially leading to high efficiencies. Here, we demonstrate initial growths of GaAs on Si_(0.9)Ge_(0.1) structures and investigate III-V on Si_(1-x)Ge_x device design with an analytical model and optoelectronic simulations. We consider Si_(0.1)Ge_(0.9) wires coated with a GaAs_(0.9)P_(0.1) shell in three different geometries: conformal, hemispherical, and spherical. The analytical model indicates that efficiencies approaching 34% are achievable with high quality materials. Full field electromagnetic simulations serve to elucidate the optical loss mechanisms and demonstrate light guiding into the wire core. Simulated current-voltage curves under solar illumination reveal the impact of a varying GaAs_(0.9)P_(0.1) minority carrier lifetime. Finally, defective regions at the hetero-interface are shown to have a negligible effect on device performance if highly doped so as to serve as a back surface field. Overall, the growths and the model demonstrate the feasibility of the proposed geometries and can be used to guide tandem wire array solar cell designs
Ribbons on the CBR Sky: A Powerful Test of a Baryon Symmetric Universe
If the Universe consists of domains of matter and antimatter, annihilations
at domain interfaces leave a distinctive imprint on the Cosmic Background
Radiation (CBR) sky. The signature is anisotropies in the form of long, thin
ribbons of width , separated by angle where L is the characteristic domain size, and
y-distortion parameter . Such a pattern could potentially be
detected by the high-resolution CBR anisotropy experiments planned for the next
decade, and such experiments may finally settle the question of whether or not
our Hubble volume is baryon symmetric.Comment: LaTeX, 10 pages, 4 figures in epsf. Revised version corrects a couple
of relevant mistake
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