448 research outputs found

    An Appraisal of the Reorganization of the San Antonio Schools

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    Progress has been made in reducing ignorance and illiteracy. The public schools have lifted the general level of education in the United States, therefore, the problem of this study is to appraise the San Antonio Public School System. Up to the present, so far as the writer has been able to ascertain, no similar study has been made to include Negro schools in the state. A similar study which included only schools for whites, an appraisal of the San Antonio Public Schools, was made by Amos Gray in 1929. Similar studies have been made by persons, but, so far as the writer has been able to find out, dealt with colleges. This study will differ from Gray\u27s in that it will be concerned with all public schools, both white and Negro. The Purpose of the study is to analyze and appraise the reorganized San Antonio Public School System, the organization of the 5-3-3 plan with its subsequent development by (1) the reaction of an appraisal jury; (2) by important appraisals, findings of the writer and others, and questionnaires. This study is extended to include all eighty-five schools in the San Antonio Independent school system both white and colored, the administrative and supervisory activities, teachers, janitors, maids, and other employees

    A food aid strategy for Haiti : maximizing developmental effectiveness

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    "The country of Haiti stands at a critical threshold for shaping its political and economic future. Concerted, visionary leadership must be put in place in order to guide the re-shaping of the Haitian economy. The purpose of this report is to provide a basis for USAID decisions about the role that its policies may play in a comprehensive agricultural development strategy for Haiti in order to insure that food needs of the country are met and that hunger and malnutrition are eliminated. Hence, both targeted projects and sectoral reforms must be addressed. Haiti presents a classic case of the political economy of hunger. Hunger and malnutrition plague the lives of a high proportion of the population, particularly the rural poor. Yet, the thrust of government policies, perhaps by necessity, has been directed toward meeting the food needs of a growing urban population. Inadequate attention has been given to developing the adaptive research and extension delivery system that will be required in order to generate major improvements in agricultural production and food distribution. The agricultural sector must play a vital role in the future in insuring that the balance-of-payments and economic growth targets of the country are achieved. Pricing policies, import regulations, and investment strategies should be designed to strengthen the developmental role of agriculture. Food aid has been used in the past to help meet the food needs of the country. Sudden periods of shortages that threaten to drive prices up too suddenly have been supplemented by food aid. Yet, the prices of domestically produced grains have risen more rapidly than the prices of imported food grains, principally wheat, minimizing the concern about price disincentives created by food aid imports. Future policy reform and sustained economic growth will require that food aid be used as a developmental resource and be fully integrated into the agricultural development strategy of the country. Its role in contributing to human resource enhancement and in capital formation that yields more secure, permanent income streams to rural residents through effectively implemented projects must be addressed."--Introduction.Dr. Brady J. Deaton (Professor of Agriculture Economics & Associate Director, Office of International Development, VPI & SU), Dr. Arthur T. Siaway (Assistant Professor, Department of Agriculture Economics Tuskegee University), Dr. Marilyn Prehm (Assistant Professor Human Nutrition & Foods, VPI & SU), Dr. Jenice Rankins (Assistant Professor, Food & Nutrition Tuskegee University), Mr. Thomas Whitney (Research Assistant, Department of Agriculture Economics, VPI & SU)Includes bibliographical references

    On Compact Routing for the Internet

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    While there exist compact routing schemes designed for grids, trees, and Internet-like topologies that offer routing tables of sizes that scale logarithmically with the network size, we demonstrate in this paper that in view of recent results in compact routing research, such logarithmic scaling on Internet-like topologies is fundamentally impossible in the presence of topology dynamics or topology-independent (flat) addressing. We use analytic arguments to show that the number of routing control messages per topology change cannot scale better than linearly on Internet-like topologies. We also employ simulations to confirm that logarithmic routing table size scaling gets broken by topology-independent addressing, a cornerstone of popular locator-identifier split proposals aiming at improving routing scaling in the presence of network topology dynamics or host mobility. These pessimistic findings lead us to the conclusion that a fundamental re-examination of assumptions behind routing models and abstractions is needed in order to find a routing architecture that would be able to scale ``indefinitely.''Comment: This is a significantly revised, journal version of cs/050802

    High frequency errors and instrument corrections of strong-motion accelerograms

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    A study of high-frequency errors present in digitized accelerograms and an analysis of the distribution of unequally spaced, hand-digitized data indicates that the Fourier content of digitized accelerogram. data may be accurate up to about 25 cps. Two methods for accelerometer instrument correction are described: (1) a direct numerical differentiation of recorded accelerograms from which high-frequency digitization errors have been filtered out and (2) an ideal "mathematical accelerometer" with a natural frequency significantly higher than the natural frequency of the recording instrument. Although both methods give good results, the first one is recommended for the standard use

    Enhanced Actin Pedestal Formation by Enterohemorrhagic Escherichia coli O157:H7 Adapted to the Mammalian Host

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    Upon intestinal colonization, enterohemorrhagic Escherichia coli (EHEC) induces epithelial cells to generate actin “pedestals” beneath bound bacteria, lesions that promote colonization. To induce pedestals, EHEC utilizes a type III secretion system to translocate into the mammalian cell bacterial effectors such as translocated intimin receptor (Tir), which localizes in the mammalian cell membrane and functions as a receptor for the bacterial outer membrane protein intimin. Whereas EHEC triggers efficient pedestal formation during mammalian infection, EHEC cultured in vitro induces pedestals on cell monolayers with relatively low efficiency. To determine whether growth within the mammalian host enhances EHEC pedestal formation, we compared in vitro-cultivated bacteria with EHEC directly isolated from infected piglets. Mammalian adaptation by EHEC was associated with a dramatic increase in the efficiency of cell attachment and pedestal formation. The amounts of intimin and Tir were significantly higher in host-adapted than in in vitro-cultivated bacteria, but increasing intimin or Tir expression, or artificially increasing the level of bacterial attachment to mammalian cells, did not enhance pedestal formation by in vitro-cultivated EHEC. Instead, a functional assay suggested that host-adapted EHEC translocate Tir much more efficiently than does in vitro-cultivated bacteria. These data suggest that adaptation of EHEC to the mammalian intestine enhances bacterial cell attachment, expression of intimin and Tir, and translocation of effectors that promote actin signaling

    The Clicker Study

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    Purpose: A recent study in orthopedics showed that clicker-based learning was more effective than traditional feedback when teaching procedures. We sought to determine whether this principle is applicable to ultrasound skills. Methods: Our prospective randomized control trial used a population of new ultrasound learners. Exclusion criteria included previous ultrasound experience of more than one hour. Students were shown an instructional video on the Focused Assessment with Sonography in Trauma (FAST) exam and randomized to receive clicker or scripted feedback. Each student performed the FAST exam once without feedback, then with either scripted or clicker-based feedback. They were timed and scored on 18 microskills. Results and Conclusions: 45 students were enrolled in the study, with 6 excluded from analysis. This included 24 premedical and 15 medical students. No significant differences were observed between groups for time or accuracy on the FAST exam. Among medical students, there was a trend toward faster results in the clicker group (mean=83 seconds) than the script group (mean=103 seconds) (p=0.22). Among undergraduates, there was a trend toward higher accuracy in the script group (mean=100%) than the clicker group (mean=95%) (p=0.068) and towards faster performance (mean=103 seconds) than the clicker group (mean=121 seconds) (p=0.38). Although no significant differences were observed, there seemed to be a trend toward faster performance with clicker feedback among medical students and faster and more accurate performance with scripted feedback among premedical students. This may be an area for future study

    Allele- and Tir-Independent Functions of Intimin in Diverse Animal Infection Models

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    Upon binding to intestinal epithelial cells, enterohemorrhagic Escherichia coli (EHEC), enteropathogenic E. coli (EPEC), and Citrobacter rodentium trigger formation of actin pedestals beneath bound bacteria. Pedestal formation has been associated with enhanced colonization, and requires intimin, an adhesin that binds to the bacterial effector translocated intimin receptor (Tir), which is translocated to the host cell membrane and promotes bacterial adherence and pedestal formation. Intimin has been suggested to also promote cell adhesion by binding one or more host receptors, and allelic differences in intimin have been associated with differences in tissue and host specificity. We assessed the function of EHEC, EPEC, or C. rodentium intimin, or a set of intimin derivatives with varying Tir-binding abilities in animal models of infection. We found that EPEC and EHEC intimin were functionally indistinguishable during infection of gnotobiotic piglets by EHEC, and that EPEC, EHEC, and C. rodentium intimin were functionally indistinguishable during infection of C57BL/6 mice by C. rodentium. A derivative of EHEC intimin that bound Tir but did not promote robust pedestal formation on cultured cells was unable to promote C. rodentium colonization of conventional mice, indicating that the ability to trigger actin assembly, not simply to bind Tir, is required for intimin-mediated intestinal colonization. Interestingly, streptomycin pre-treatment of mice eliminated the requirement for Tir but not intimin during colonization, and intimin derivatives that were defective in Tir-binding still promoted colonization of these mice. These results indicate that EPEC, EHEC, and C. rodentium intimin are functionally interchangeable during infection of gnotobiotic piglets or conventional C57BL/6 mice, and that whereas the ability to trigger Tir-mediated pedestal formation is essential for colonization of conventional mice, intimin provides a Tir-independent activity during colonization of streptomycin pre-treated mice

    Phase Chemistry and Radionuclide Retention of High-Level Radioactive Waste Tank Sludges

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    The US Department of Energy (DOE) has millions of gallons of high level nuclear waste stored in underground tanks at Hanford, Washington and Savannah River, South Carolina. These tanks will eventually be emptied and decommissioned. This will leave a residue of sludge adhering to the interior tank surfaces that may contaminate groundwaters with radionuclides and RCRA metals. Experimentation on such sludges is both dangerous and prohibitively expensive so there is a great advantage to developing artificial sludges. The US DOE Environmental Management Science Program (EMSP) has funded a program to investigate the feasibility of developing such materials. The following text reports on the success of this program, and suggests that much of the radioisotope inventory left in a tank will not move out into the surrounding environment. Ultimately, such studies may play a significant role in developing safe and cost effective tank closure strategies

    Fault Tolerance in Protein Interaction Networks: Stable Bipartite Subgraphs and Redundant Pathways

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    As increasing amounts of high-throughput data for the yeast interactome become available, more system-wide properties are uncovered. One interesting question concerns the fault tolerance of protein interaction networks: whether there exist alternative pathways that can perform some required function if a gene essential to the main mechanism is defective, absent or suppressed. A signature pattern for redundant pathways is the BPM (between-pathway model) motif, introduced by Kelley and Ideker. Past methods proposed to search the yeast interactome for BPM motifs have had several important limitations. First, they have been driven heuristically by local greedy searches, which can lead to the inclusion of extra genes that may not belong in the motif; second, they have been validated solely by functional coherence of the putative pathways using GO enrichment, making it difficult to evaluate putative BPMs in the absence of already known biological annotation. We introduce stable bipartite subgraphs, and show they form a clean and efficient way of generating meaningful BPMs which naturally discard extra genes included by local greedy methods. We show by GO enrichment measures that our BPM set outperforms previous work, covering more known complexes and functional pathways. Perhaps most importantly, since our BPMs are initially generated by examining the genetic-interaction network only, the location of edges in the protein-protein physical interaction network can then be used to statistically validate each candidate BPM, even with sparse GO annotation (or none at all). We uncover some interesting biological examples of previously unknown putative redundant pathways in such areas as vesicle-mediated transport and DNA repair
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