20,960 research outputs found

    Test Results of the Modified Space Shuttle Main Engine at the Marshall Space Flight Center Technology Test Bed Facility

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    A modified space shuttle main engine (SSME), which primarily includes an enlarged throat main combustion chamber with the acoustic cavities removed and a main injector with the stability control baffles removed, was tested. This one-of-a-kind engine's design changes are being evaluated for potential incorporation in the shuttle flight program in the mid-1990's. Engine testing was initiated on September 15, 1988 and has accumulated 1,915 seconds and 19 starts. Testing is being conducted to characterize the engine system performance, combustion stability with the baffle-less injector, and both low pressure oxidizer turbopump (LPOTP) and high pressure oxidizer turbopump (HPOTP) for suction performance. These test results are summarized and compared with the SSME flight configuration data base. Testing of this new generation SSME is the first product from the technology test bed (TTB). Figure test plans for the TTB include the highly instrumented flight configuration SSME and advanced liquid propulsion technology items

    Vegetarianism

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    Ethical vegetarians maintain that vegetarianism is morally required. The principal reasons offered in support of ethical vegetarianism are: (i) concern for the welfare and well-being of the animals being eaten, (ii) concern for the environment, (iii) concern over global food scarcity and the just distribution of resources, and (iv) concern for future generations. Each of these reasons is explored in turn, starting with a historical look at ethical vegetarianism and the moral status of animals

    The HPV cellular transactivator Brn-3a can be used to predict cervical adenocarcinoma and squamous carcinoma precancer lesions in the developed and developing worlds

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    The cellular transactivator Brn-3a has previously been shown to be expressed at elevated levels in the cervix of women with squamous cell carcinoma of the cervix (SCC) and to activate the expression of HPV E6 mRNA. In this study, we show that common and rare cervical precancer lesions, including those of adenocarcinoma (AC), which are usually difficult to diagnose using classical procedures, also expressed high levels of Brn-3a and can be diagnosed by measuring the levels of Brn-3a and E6 mRNAs

    Comparison of stroke volume measurement between non-invasive bioreactance and esophageal Doppler in patients undergoing major abdominal-pelvic surgery

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    PURPOSE: Bioreactance is a non-invasive technology for measuring stroke volume (SV) in the operating room and critical care setting. We evaluated how the NICOM® bioreactance device performed against the CardioQ® esophageal Doppler monitor in patients undergoing major abdominal–pelvic surgery, focusing on the effect of different hemodynamic interventions. METHODS: SVNICOM and SVODM were simultaneously measured intraoperatively, including before and after interventions including fluid challenge, vasopressor boluses, peritoneal gas insufflation/removal, and Trendelenburg/reverse Trendelenburg patient positioning. RESULTS: A total of 768 values were collected from 21 patients. Pre- and post-intervention measures were recorded on 155 occasions. Bland–Altman analysis revealed a bias of 8.6 ml and poor precision with wide limits of agreement (54 and −37 ml) and a percentage error of 50.6%. No improvement in precision was detected after taking into account repeated measurements for each patient (bias: 8 ml; limits of agreement: 74 and −59 ml). Concordance between changes in SVNICOM and SVODM before and after interventions was also poor: 78.7% (all measures), 82.4% (after vasopressor administration), and 74.3% (after fluid challenge). Using Doppler SV as the reference technique, the area under the receiver operating characteristic curve assessing the ability of the NICOM device to predict fluid responsiveness was 0.81 (0.7–0.9). CONCLUSIONS: In patients undergoing major abdomino-pelvic surgery, SV values obtained by NICOM showed neither clinically or statistically acceptable agreement with those obtained by esophageal Doppler. Although, in the setting of this study, bioreactance technology cannot reliably replace esophageal Doppler monitoring, its accuracy for predicting fluid responsiveness was higher, up to approximately 80%

    Discrimination against Mixed-Status Families and its Health Impact on Latino Children

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    Background and Objective: Restrictive immigration policies and discrimination are associated with negative health outcomes for immigrant and Latino families. Mixed-status families represent a unique subpopulation of Latinos affected by restrictive immigration policies. This qualitative study explored discrimination against mixed-status families and its potential health impact on Latino children from the perspective of Latina mothers. Methods: In 2017, twenty in-depth interviews with Latina mothers of mixed-status families living in northwestern North Carolina were conducted, transcribed, and analyzed. Constant comparison, an approach to grounded theory development, was used. Results: Nine themes emerged that reflected experiences with discrimination and its negative impact on children. Themes included more frequent and severe discrimination during and after the 2016 US presidential election, determination to stay together and remain in the US, experiences of discrimination in multiple settings, the impact of discrimination on child health and well-being, the impact of fear and stress on meeting the needs of children, the burden on children serving as liaisons between families and services, the inability of citizenship to protect against the effects of discrimination, positive and hopeful responses to discrimination, and the potential role of education in building a foundation for reducing discrimination (and thus promoting the health and well-being of Latino children) in the future. Conclusions: Discrimination against mixed-status Latino families constitutes a critical threat to the health and well-being of Latino children. Further research should inform immigration policies that support (rather than threaten) the health, well-being, and health care practices that mitigate the stresses experienced by Latino children

    A Rare Case of Diffuse Polyarthritis in the Context of an Epididymoorchitis due to Mumps Infection

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    Mumps is a childhood disease with declining incidence in the western world and arthritis is a rare complication associated to the disease. Various presentations exist making diagnosis even more challenging. The mechanisms responsible for the joint involvement remain largely unknown but the timing of onset of the symptoms usually coincide with the rise in antibody titers arguing for an immunologic mediated response. We hereby report a rare case of polyarthritis in the onset of epididymoorchitis due to mumps infection in a HIV infected male patient. Elevated IL-6 serum level in our patient suggests that this cytokine may be an interesting biomarker for the diagnosis of mumps related arthritis

    The Algebras of Large N Matrix Mechanics

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    Extending early work, we formulate the large N matrix mechanics of general bosonic, fermionic and supersymmetric matrix models, including Matrix theory: The Hamiltonian framework of large N matrix mechanics provides a natural setting in which to study the algebras of the large N limit, including (reduced) Lie algebras, (reduced) supersymmetry algebras and free algebras. We find in particular a broad array of new free algebras which we call symmetric Cuntz algebras, interacting symmetric Cuntz algebras, symmetric Bose/Fermi/Cuntz algebras and symmetric Cuntz superalgebras, and we discuss the role of these algebras in solving the large N theory. Most important, the interacting Cuntz algebras are associated to a set of new (hidden) local quantities which are generically conserved only at large N. A number of other new large N phenomena are also observed, including the intrinsic nonlocality of the (reduced) trace class operators of the theory and a closely related large N field identification phenomenon which is associated to another set (this time nonlocal) of new conserved quantities at large N.Comment: 70 pages, expanded historical remark
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