Development of detonation reaction engine

Reaction engine operates on the principle of a controlled condensed detonation. In this engine the gas products that are expelled from the engine to produce thrust are generated by the condensed detonation reaction. The engine is constructed of two basic sections consisting of a detonation wave generator section and a condensed detonation reaction section

Continuous detonation reaction engine

Reaction engine operates on the principles of a controlled condensed detonation rather than on the principles of gas expansion. The detonation results in reaction products that are expelled at a much higher velocity

Educational Leadership Preparation: What Supervisors, Candidates, And Mentors Said

The findings of this study identified practicum areas that meet the educational demands of candidates while highlighting practicum areas that need improvement. The study contributes to the knowledge base of the field by drawing upon feedback from university supervisors, school mentors and program candidates to evaluate and improve the practicum experience in the educational leadership program. Program candidates are in the best position to discuss their recent experiences of exposure to the real world. Supervisors and mentors can witness from their first hand experience how effective practicum activities work. Responses from supervisors, mentors and candidates regarding leadership practicum experiences are valuable to program developers in their future program redesign effort. Practicum experiences expose candidates to real-world school leadership experiences. Unfortunately, because of all kinds of conditional limitations, such practicum experiences can only be offered in conjunction with candidates' regular work in school. However, leadership practicum experiences can be well planned with a high collaboration of supervisors, mentors and candidates who have an invested interest in school improvement. In this study, what we learn from the differences of perceptions among supervisors, mentors and candidates is a caution to all stakeholders that we need to do a better job to prepare the next generation of school leaders. Supervisors, mentors and candidates need to form a coalition to explore other options, especially out-of-the-box strategies, to deliver a highly effective practicum program for potential educational leaders.&nbsp

Mu and Tau Neutrino Thermalization and Production in Supernovae: Processes and Timescales

We investigate the rates of production and thermalization of $\nu_\mu$ and $\nu_\tau$ neutrinos at temperatures and densities relevant to core-collapse supernovae and protoneutron stars. Included are contributions from electron scattering, electron-positron annihilation, nucleon-nucleon bremsstrahlung, and nucleon scattering. For the scattering processes, in order to incorporate the full scattering kinematics at arbitrary degeneracy, the structure function formalism developed by Reddy et al. (1998) and Burrows and Sawyer (1998) is employed. Furthermore, we derive formulae for the total and differential rates of nucleon-nucleon bremsstrahlung for arbitrary nucleon degeneracy in asymmetric matter. We find that electron scattering dominates nucleon scattering as a thermalization process at low neutrino energies ($\epsilon_\nu\lesssim 10$ MeV), but that nucleon scattering is always faster than or comparable to electron scattering above $\epsilon_\nu\simeq10$ MeV. In addition, for $\rho\gtrsim 10^{13}$ g cm$^{-3}$, $T\lesssim14$ MeV, and neutrino energies $\lesssim60$ MeV, nucleon-nucleon bremsstrahlung always dominates electron-positron annihilation as a production mechanism for $\nu_\mu$ and $\nu_\tau$ neutrinos.Comment: 29 pages, LaTeX (RevTeX), 13 figures, submitted to Phys. Rev. C. Also to be found at anonymous ftp site http://www.astrophysics.arizona.edu; cd to pub/thompso

Aortic bifurcation angle as an independent risk factor for aortoiliac occlusive disease

Recently, there has been interest in potential geometric risk factors that might result in or exaggerate atherosclerosis. The aortic bifurcation is a complex anatomical area dividing the high pressure blood of the descending abdominal aorta into the lower limbs and pelvis. The distribution of the bifurcation angle and any asymmetry, its relation with age and its possible contribution to the risk of aortoiliac atherosclerosis are presented here. Statistical analysis was performed by SPSS version 11.0 using, Fisher`s exact test, the Pearson and Spearman correlation tests and logistic regression analysis. The p value was set at 0.05. No correlations were found between age, bifurcation angle and angle asymmetry in the Pearson test (p > 0.05). Logistic regression analysis revealed that the bifurcation angle, but not its asymmetry, gender or age, was a significant and independent risk factor for aortoiliac atherosclerosis (model r2 = 0.662, p = 0.027). With additional study these results may have implications regarding risk factors for aortoiliac atherosclerosis. To our knowledge, this study is the first of its kind to indicate the potential of such an important geometric risk factor for atherosclerosis at the aortic bifurcation

An Observational Study of Nurse Staffing Ratios and Hospital Readmission among Children Admitted for Common Conditions

Background: Hospital patient-to-nurse staffing ratios are associated with quality outcomes in adult patient populations but little is known about how these factors affect paediatric care. We examined the relationship between staffing ratios and all-cause readmission (within 14 days, 15–30 days) among children admitted for common medical and surgical conditions. Methods: We conducted an observational cross-sectional study of readmissions of children in 225 hospitals by linking nurse surveys, inpatient discharge data and information from the American Hospital Association Annual Survey. Registered Nurses (N=14 194) providing direct patient care in study hospitals (N=225) and children hospitalised for common conditions (N=90 459) were included. Results: Each one patient increase in a hospital\u27s average paediatric staffing ratio increased a medical child\u27s odds of readmission within 15–30 days by a factor of 1.11, or by 11% (95% CI 1.02 to 1.20) and a surgical child\u27s likelihood of readmission within 15–30 days by a factor of 1.48, or by 48% (95% CI 1.27 to 1.73). Children treated in hospitals with paediatric staffing ratios of 1 : 4 or less were significantly less likely to be readmitted within 15–30 days. There were no significant effects of nurse staffing ratios on readmissions within 14 days. Discussion: Children with common conditions treated in hospitals in which nurses care for fewer patients each are significantly less likely to experience readmission between 15 and 30 days after discharge. Lower patient-to-nurse ratios hold promise for preventing unnecessary hospital readmissions for children through more effective predischarge monitoring of patient conditions, improved discharge preparation and enhanced quality improvement success

Patterned feeding experience for preterm infants: study protocol for a randomized controlled trial

Background Neurobehavioral disabilities occur in 5–15 % of preterm infants with an estimated 50–70 % of very low birth weight preterm infants experiencing later dysfunction, including cognitive, behavioral, and social delays that often persist into adulthood. Factors implicated in poor neurobehavioral and developmental outcomes are hospitalization in the neonatal intensive care unit (NICU) and inconsistent caregiving patterns. Although much underlying brain damage occurs in utero or shortly after birth, neuroprotective strategies can stop lesions from progressing, particularly when these strategies are used during the most sensitive periods of neural plasticity occurring months before term age. The purpose of this randomized trial is to test the effect of a patterned feeding experience on preterm infants’ neurobehavioral organization and development, cognitive function, and clinical outcomes. Methods This trial uses an experimental, longitudinal, 2-group design with 120 preterm infants. Infants are enrolled within the first week of life and randomized to an experimental group receiving a patterned feeding experience from the first gavage feeding through discharge or to a control group receiving usual feeding care experience. The intervention involves a continuity of tactile experiences associated with feeding to train and build neuronal networks supportive of normal infant feeding experience. Primary outcomes are neurobehavioral organization as measured by Neurobehavioral Assessment of the Preterm Infant at 3 time points: the transition to oral feedings, NICU discharge, and 2 months corrected age. Secondary aims are cognitive function measured using the Bayley Scales of Infant and Toddler Development, Third Edition at 6 months corrected age, neurobehavioral development (sucking organization, feeding performance, and heart rate variability), and clinical outcomes (length of NICU stay and time to full oral feeding). The potential effects of demographic and biobehavioral factors (perinatal events and conditions of maternal or fetal/newborn origin and immunologic and genetic biomarkers) on the outcome variables will also be considered. Discussion Theoretically, the intervention provided at a critical time in neurologic system development and associated with a recurring event (feeding) should enhance neural connections that may be important for later development, particularly language and other cognitive and neurobehavioral organization skills

Sex determination from partial segments and maximum femur lengths in Koreans using computed tomography

Background: The aim of this study was to establish standards for determining sex from fragmentary and complete femurs in a Korean population.Materials and methods: The statistical analysis of 12 variables (6 about breadth and 6 about length) based on 100 Korean femurs (from 50 males and 50 females) showed that all variables have significant sex differences.Results: The most accurate discriminant variable was the condylar breadth parallel with epicondylar breadth (87.6% accuracy). In contrast, the transverse shaft diameter was not a discriminant variable for sex determination (67.0% accuracy). Breadth-related variables were generally more accurate than length-related variables. Three variables (vertical diameter of the neck [VDN], medial epicondylarlength [MCL], and condylar breadth [CB]) were selected from stepwise analysis fordiscriminating sex (93.5% accuracy). The discriminating equation was as follows: 0.171 × VDN + 0.172 × MCL + 0.128 × CB2 – 21.471.Conclusions: The results of this study are helpful for determining sex, even if a femur is found in a fragmented condition in the field

Postrenal transplant hemophagocytic lymphohistiocytosis and thrombotic microangiopathy associated with parvovirus B19 infection

Persistent anemia is a known consequence of Parvovirus B19 (B19) infection following renal transplantation. However, to date, no description of B19-related hemophagocytic lymphohistiocytosis (HLH) exists in renal transplant recipients. We report a 24-year-old male kidney recipient, who presented with fever, severe anemia and allograft dysfunction two years following transplantation. Hyperferritinemia, hypertriglyceridemia, elevated serum lactate dehydrogenase, pancytopenia and fragmented red blood cells on the peripheral blood were also noted. Bone marrow examination revealed giant pronormoblasts and frequent histiocytes with intracellular hematopoietic elements, consistent with HLH. Renal allograft biopsy revealed closure of the lumen of glomerular capillaries and thickening of the capillary walls compatible with thrombotic microangiopathy. The presence of anti-B19 IgM antibody and viral DNA in the patient's serum (detected by real-time PCR) confirmed an acute B19 infection. Following high-dose intravenous immunoglobulin therapy, the anemia gradually resolved and renal function improved. As far as we know, this is the first report of B19-associated HLH and thrombotic microangiopathy in a renal transplant recipient. © 2008 The Authors