2,594 research outputs found
On the detection of newly created CN radicals and comets
Laboratory investigations of CN radical formation by photodissociation of parent molecules have suggested the possibility of observing emission lines in cometary spectra from newly formed CN radicals. These laboratory studies have shown that high initial internal excitation of CN is the rule with excitation of rotational levels N up to 70. In the collisionless environment of the cometary atmosphere this initial excitation would yield a corresponding distribution for the lowest vibrational level of the ground X(2) Sigma (+) state. Our calculations show that it is feasible with present observational techniques to detect photochemically excited lines with N approx. equal to 30 in the 0-0 band of the violet system
Advanced rocket engine cryogenic turbopump bearing thermal model
A lumped node thermal model was developed representing the Space Shuttle Main Engine (SSME) liquid oxygen (LOX) turbopump turbine end bearings operating in a cryogenically cooled bearing tester. Bearing elements, shaft, carrier, housing, cryogen flow characteristics, friction heat, and fluid viscous energy are included in the model. Heat transfer characteristics for the regimes of forced convection boiling are modeled for liquid oxygen (LOX) and liquid nitrogen (LN2). Large temperature differences between the cryogenic fluid and baring contact surfaces require detailed nodal representation in these areas. Internal loads and friction heat are affected by temperature dependent operating clearances requiring iterations between bearing thermal and mechanical models. Analyses indicate a thermal-mechanical coupling resulting in reduced operating clearances, increased loading and heating which can contribute to premature bearing failure. Contact surfaces operate at temperatures above local saturation resulting in vapor rather than liquid in the contacts, precluding possible liquid film lubrication. Elevated temperatures can reduce lubrication, increase friction, and reduce surface hardness supporting a surface failure mode rather than subsurface fatigue
Theory and Application of Dissociative Electron Capture in Molecular Identification
The coupling of an electron monochromator (EM) to a mass spectrometer (MS)
has created a new analytical technique, EM-MS, for the investigation of
electrophilic compounds. This method provides a powerful tool for molecular
identification of compounds contained in complex matrices, such as
environmental samples. EM-MS expands the application and selectivity of
traditional MS through the inclusion of a new dimension in the space of
molecular characteristics--the electron resonance energy spectrum. However,
before this tool can realize its full potential, it will be necessary to create
a library of resonance energy scans from standards of the molecules for which
EM-MS offers a practical means of detection. Here, an approach supplementing
direct measurement with chemical inference and quantum scattering theory is
presented to demonstrate the feasibility of directly calculating resonance
energy spectra. This approach makes use of the symmetry of the
transition-matrix element of the captured electron to discriminate between the
spectra of isomers. As a way of validating this approach, the resonance values
for twenty-five nitrated aromatic compounds were measured along with their
relative abundance. Subsequently, the spectra for the isomers of nitrotoluene
were shown to be consistent with the symmetry-based model. The initial success
of this treatment suggests that it might be possible to predict negative ion
resonances and thus create a library of EM-MS standards.Comment: 18 pages, 7 figure
On the Chopping Block: Examining the Fairness of Observational Data of Teacher Effectiveness
Since the No Child Left Behind legislation, the assessment of teacher effectiveness (TE) for accountability purposes has been at the forefront of educational policy. Prominent among both already-existing and newly developed measures is the Classroom Assessment Scoring System (CLASS; Pianta, La Paro, & Hamre, 2008). The CLASS is used currently in over 40 states across the country (Teachstone, 2013; Office of Head Start, 2014) to make high-stakes decisions for teachers, including compensation, promotion, and termination. For this reason, it is important that measures like the CLASS are evaluated by research. Our research hypothesizes that if measures like the CLASS can be reliably used for high-stakes outcomes, then scores for individual teachers should remain stable over time, and particularly so within units of thematically related lessons. We used a single-subject design, reflective of the real-world uses of TE scores, to assess score stability for two kindergarten teachers purposively selected from a larger database. Stability ranges were created around mean scores and then visually examined. Significant variability was found between lessons for both teachers, particularly in the instructional support domain of the CLASS. We conclude that single observations are likely not sufficient to reliably evaluate teachers’ instructional effectiveness. Further research should investigate: (1) if similar variability is found with a larger number of teachers when observed for longer periods of time; (2) if this instability is found when using other TE measures; (3) the factors that contribute to observed instability; and (4) the number of teacher observations needed to obtain accurate views of teachers’ effectiveness patterns
Diagnostic Medical Errors: Patient\u27s Perspectives on a Pervasive Problem
Introduction. The Institute of Medicine defines diagnostic error as the failure to establish an accurate or timely explanation for the patient\u27s health problem(s), or effectively communicate the explanation to the patient. To our knowledge, no studies exist characterizing diagnostic error from patient perspectives using this definition.
Objective. We sought to characterize diagnostic errors experienced by patients and describe patient perspectives on causes, impacts, and prevention strategies.
Methods. We screened 77 adult inpatients at University of Vermont Medical Center and conducted 27 structured interviews with patients who experienced diagnostic error in the past five years. We performed qualitative analysis using Grounded Theory.
Results. In the past five years, 39% of interviewed patients experienced diagnostic error. The errors mapped to the following categories: accuracy (30%), communication (34%) and timeliness (36%). Poor communication (13 responses) and inadequate time with doctors (7) were the most identified causes of errors. Impacts of errors included emotional distress (17 responses), adverse health outcomes (7) and impaired activities of daily living (6). Patients suggested improved communication (11 responses), clinical management (7) and access to doctors (5) as prevention strategies. For communication, patients rated talk to your doctor highest (mean 8.4, on 1-10 Likert scale) and text message lowest (4.8).
Conclusions/Recommendations. Diagnostic errors are common and have dramatic impact on patients\u27 well-being. We suggest routine surveillance to identify errors, support for patients who have experienced errors, and implementation of patient and provider checklists to enhance communication. Future studies should investigate strategies to allow care providers adequate time with patients.https://scholarworks.uvm.edu/comphp_gallery/1246/thumbnail.jp
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Bearing witness and being bounded; the experiences of nurses in adult critical care in relation to the survivorship needs of patients and families
Aim: To discern and understand the responses of nurses to the survivorship needs of patients and family members in adult critical care units.
Background: The critical care environment is a demanding place of work which may limit nurses to immediacy of care, such is the proximity to death and the pressure of work.
Design: A constructivist grounded theory approach with constant comparative analysis.
Methods: As part of a wider study and following ethical approval, eleven critical care nurses working within a general adult critical care unit were interviewed with respect to their experiences in meeting the psychosocial needs of patients and family members. Through the process of constant comparative analysis an overarching selective code was constructed. EQUATOR guidelines for qualitative research (COREQ) applied.
Results: The data illuminated a path of developing expertise permitting integration of physical, psychological and family care with technology and humanity. Gaining such proficiency is demanding and the data presented reveals the challenges that nurses experience along the way.
Conclusion: The study confirms that working within a critical care environment is an emotionally charged challenge and may incur an emotional cost. Nurses can find themselves bounded by the walls of the critical care unit and experience personal and professional conflicts in their role. Nurses bear witness to the early stages of the survivorship trajectory but are limited in their support of ongoing needs.
Relevance to Clinical Practice: Critical care nurses can experience personal and professional conflicts when caring for both patients and families. This can lead to moral distress and may contribute to compassion fatigue. Critical care nurses appear bounded to the delivery of physiological and technical care, in the moment, as demanded by the patient's acuity. Consequentially this limits nurses’ ability to support the onward survivorship trajectory. Increased pressure and demands on critical care beds has contributed further to occupational stress in this care setting
763-1 Assessment of Left Ventricular Function by Circumferential Stress-Midwall Shortening Relations in Dilated Cardiomyopathy
Echocardiographic stress endocardial shortening relations provide estimates of LV contractility that do not uniformly detect myocardial dysfunction in dilated cardiomyopathy (DCM). Recently it has become apparent that midwall (mid) fractional shortening and circumferential (c) end-systolic stress (ESS) provide the most appropriate paired afterload and function measures. Both meridional (m) and cESS were related to both endocardial (e) FS and midFS in 42 patients with DCM (98% dead during follow-up; eFS =4% in the survivor) and in 140 normals. Eight patients (19%) fell into the 95% confidence interval of the normal relation of eFS to mESS (top panel), 14% had apparently normal midFS-mESS relations but midFS was depressed in relation to cESS in 100% of patients (lower panel). Thus, (1) use of cESS-shortening relations improves the ability to identify patients with depressed LV function; (2) use of midFS or eFS are equivalent in DCM with LV dilatation and wall thinning
Solar Thermal Upper Stage Liquid Hydrogen Pressure Control Testing
High-energy cryogenic propellant is an essential element in future space exploration programs. Therefore, NASA and its industrial partners are committed to an advanced development/technology program that will broaden the experience base for the entire cryogenic fluid management community. Furthermore, the high cost of microgravity experiments has motivated NASA to establish government/aerospace industry teams to aggressively explore combinations of ground testing and analytical modeling to the greatest extent possible, thereby benefitting both industry and government entities. One such team consisting of ManTech SRS, Inc., Edwards Air Force Base, and Marshall Space Flight Center (MSFC) was formed to pursue a technology project designed to demonstrate technology readiness for an SRS liquid hydrogen (LH2) in-space propellant management concept. The subject testing was cooperatively performed June 21-30, 2000, through a partially reimbursable Space Act Agreement between SRS, MSFC, and the Air Force Research Laboratory. The joint statement of work used to guide the technical activity is presented in appendix A. The key elements of the SRS concept consisted of an LH2 storage and supply system that used all of the vented H2 for solar engine thrusting, accommodated pressure control without a thermodynamic vent system (TVS), and minimized or eliminated the need for a capillary liquid acquisition device (LAD). The strategy was to balance the LH2 storage tank pressure control requirements with the engine thrusting requirements to selectively provide either liquid or vapor H2 at a controlled rate to a solar thermal engine in the low-gravity environment of space operations. The overall test objective was to verify that the proposed concept could enable simultaneous control of LH2 tank pressure and feed system flow to the thruster without necessitating a TVS and a capillary LAD. The primary program objectives were designed to demonstrate technology readiness of the SRS concept at a system level as a first step toward actual flight vehicle demonstrations. More specific objectives included testing the pressure and feed control system concept hardware for functionality, operability, and performance. Valuable LH2 thermodynamic and fluid dynamics data were obtained for application to both the SRS concept and to future missions requiring space-based cryogen propellant management
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