523 research outputs found
Analysis of a space emergency ammonia dump using the FLOW-NET two-phase flow program
Venting of cryogenic and non-cryogenic fluids to a vacuum or a very low pressure will take place in many space-based systems that are currently being designed. This may cause liquid freezing either internally within the flow circuit or on external spacecraft surfaces. Typical ammonia flow circuits were investigated to determine the effect of the geometric configuration and initial temperature, pressure, and void fraction on the freezing characteristics of the system. The analysis was conducted also to investigate the ranges of applicability of the FLOW-NET program. It was shown that a typical system can be vented to very low liquid fractions before freezing occurs. However, very small restrictions in the flow circuit can hasten the inception of freezing. The FLOW-NET program provided solutions over broad ranges of system conditions, such as venting of an ammonia tank, initially completely filled with liquid, through a series of contracting and expanding line cross sections to near-vacuum conditions
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Numerical calculation of flashing from long pipes using a two-field model
A two-field model for two-phase flows, in which the vapor and liquid phases have different densities, velocities, and temperatures, has been used to calculate the flashing of water from long pipes. The IMF (Implicit Multifield) technique is used to numerically solve the transient equations that govern the dynamics of each phase. The flow physics is described with finite rate phase transitions, interfacial friction, heat transfer, pipe wall friction, and appropriate state equations. The results of the calculations are compared with measured histories of pressure, temperature, and void fraction. A parameter study indicates the relative sensitivity of the results to the various physical models that are used. (auth
Reflections on using a community-based and multisystem approach to transforming school-based intervention for children with developmental motor disorders
Evidence-based management of Developmental Coordination Disorder (DCD) in school-age children requires putting into practice the best and most current research findings, including evidence that early identification, self-management, prevention of secondary disability, and enhanced participation are the most appropriate foci of school-based occupational therapy. Partnering for Change (P4C) is a new school-based intervention based upon these principles that has been developed and evaluated in Ontario, Canada over an 8-year period. Our experience to date indicates that its implementation in schools is highly complex with involvement of multiple stakeholders across health and education sectors. In this paper, we describe and reflect upon our team’s experience in using community-based participatory action research, knowledge translation, and implementation science to transform evidence-informed practice with children who have DCD
Production of Medical Radioisotopes with High Specific Activity in Photonuclear Reactions with Beams of High Intensity and Large Brilliance
We study the production of radioisotopes for nuclear medicine in
photonuclear reactions or ()
photoexcitation reactions with high flux [()/s], small
diameter m and small band width () beams produced by Compton back-scattering of laser
light from relativistic brilliant electron beams. We compare them to (ion,np) reactions with (ion=p,d,) from particle accelerators like
cyclotrons and (n,) or (n,f) reactions from nuclear reactors. For
photonuclear reactions with a narrow beam the energy deposition in the
target can be managed by using a stack of thin target foils or wires, hence
avoiding direct stopping of the Compton and pair electrons (positrons).
isomer production via specially selected cascades
allows to produce high specific activity in multiple excitations, where no
back-pumping of the isomer to the ground state occurs. We discuss in detail
many specific radioisotopes for diagnostics and therapy applications.
Photonuclear reactions with beams allow to produce certain
radioisotopes, e.g. Sc, Ti, Cu, Pd, Sn,
Er, Pt or Ac, with higher specific activity and/or
more economically than with classical methods. This will open the way for
completely new clinical applications of radioisotopes. For example Pt
could be used to verify the patient's response to chemotherapy with platinum
compounds before a complete treatment is performed. Also innovative isotopes
like Sc, Cu and Ac could be produced for the first time
in sufficient quantities for large-scale application in targeted radionuclide
therapy.Comment: submitted to Appl. Phys.
Obesity and diabetes genes are associated with being born small for gestational age: Results from the Auckland Birthweight Collaborative study
Background: Individuals born small for gestational age (SGA) are at increased risk of rapid postnatal weight gain, later obesity and diseases in adulthood such as type 2 diabetes, hypertension and cardiovascular diseases. Environmental risk factors for SGA are well established and include smoking, low pregnancy weight, maternal short stature, maternal diet, ethnic origin of mother and hypertension. However, in a large proportion of SGA, no underlying cause is evident, and these individuals may have a larger genetic contribution. Methods: In this study we tested the association between SGA and polymorphisms in genes that have previously been associated with obesity and/or diabetes. We undertook analysis of 54 single nucleotide polymorphisms (SNPs) in 546 samples from the Auckland Birthweight Collaborative (ABC) study. 227 children were born small for gestational age (SGA) and 319 were appropriate for gestational age (AGA). Results and Conclusion: The results demonstrated that genetic variation in KCNJ11, BDNF, PFKP, PTER and SEC16B were associated with SGA and support the concept that genetic factors associated with obesity and/or type 2 diabetes are more prevalent in those born SGA compared to those born AGA. We have previously determined that environmental factors are associated with differences in birthweight in the ABC study and now we have demonstrated a significant genetic contribution, suggesting that the interaction between genetics and the environment are important
Daycare attendance and risk of childhood acute lymphoblastic leukaemia
The relationship between daycare/preschool (‘daycare’) attendance and the risk of acute lymphoblastic leukaemia was evaluated in the Northern California Childhood Leukaemia Study. Incident cases (age 1–14 years) were rapidly ascertained during 1995–1999. Population-based controls were randomly selected from the California birth registry, individually matched on date of birth, gender, race, Hispanicity, and residence, resulting in a total of 140 case–controls pairs. Fewer cases (n=92, 66%) attended daycare than controls (n=103, 74%). Children who had more total child–hours had a significantly reduced risk of ALL. The odds ratio associated with each thousand child–hours was 0.991 (95% confidence interval (CI): 0.984–0.999), which means that a child with 50 thousand child–hours (who may have, for example, attended a daycare with 15 other children, 25 h per week, for a total duration of 30.65 months) would have an odds ratio of (0.991)50=0.64 (95% CI: 0.45, 0.95), compared to children who never attended daycare. Besides, controls started daycare at a younger age, attended daycare for longer duration, remained in daycare for more hours, and were exposed to more children at each daycare. These findings support the hypothesis that delayed exposure to common infections plays an important role in the aetiology of childhood acute lymphoblastic leukaemia, and suggest that extensive contact with other children in a daycare setting is associated with a reduced risk of acute lymphoblastic leukaemia
Impaired Collateral Recruitment and Outward Remodeling in Experimental Diabetes
OBJECTIVE—In this study, the effect of chronic hyperglycemia on acute ligation-induced collateral vasodilation, on monocyte chemotaxis, and on structural outward remodeling of collaterals was investigated
Influence of Efforts of Employer and Employee on Return-to-Work Process and Outcomes
Background Research on disability and RTW outcome has led to significant advances in understanding these outcomes, however, limited studies focus on measuring the RTW process. After a prolonged period of sickness absence, the assessment of the RTW process by investigating RTW Effort Sufficiency (RTW-ES) is essential. However, little is known about factors influencing RTW-ES. Also, the correspondence in factors determining RTW-ES and RTW is unknown. The purpose of this study was to investigate 1) the strength and relevance of factors related to RTW-ES and RTW (no/partial RTW), and 2) the comparability of factors associated with RTW-ES and with RTW. Methods During 4 months, all assessments of RTW-ES and RTW (no/partial RTW) among employees applying for disability benefits after 2 years of sickness absence, performed by labor experts at 3 Dutch Social Insurance Institute locations, were investigated by means of a questionnaire. Results Questionnaires concerning 415 cases were available. Using multiple logistic regression analysis, the only factor related to RTW-ES is a good employer-employee relationship. Factors related to RTW (no/partial RTW) were found to be high education, no previous periods of complete disability and a good employer-employee relationship. Conclusions Different factors are relevant to RTW-ES and RTW, but the employer-employee relationship is relevant for both. Considering the importance of the assessment of RTW-ES after a prolonged period of sickness absence among employees who are not fully disabled, this knowledge is essential for the assessment of RTW-ES and the RTW process itself
Regulation of PTP1D mRNA by Peptide Growth Factors in the Human Endometrial Cell Line HEC-1-A
Objective: To assess, in the human endometrial cell line HEC-1-A, the presence of protein tyrosine phosphatase 1D (PTDP1D) and the possible regulation of its mRNA expression by mitogens such as forskolin (an agent that increases intracellular cyclic adenosine monophosphate [cAMP] levels), epidermal growth factor (EGF), and insulin-like growth factor-I (IGF-I). Methods: Cells were grown to confluence and maintained in serum-free media for 24 hours before treatment. Cells were exposed to forskolin, EGF, and IGF-I for increasing time periods (0, 1, 3, 6, and 24 hours), and PTP1D mRNA expression was determined by Northern blot analysis. In addition, cells were incubated with increasing doses of forskolin (final concentrations: 1, 5, 10, 20, and 30 μmol/L0 for 6 hours. Results: When treated with the various mitogens, cells increased their stimulation of PTP1D mRNA expression in a time- and dose-dependent fashion. Specifically, forskolin, EGF, and IGF-I induced maximal mRNA expression at 6, 3, and 6 hours, respectively. Expression induced by forskolin, EGF, and IGF-I was five, three, and six times control levels, respectively. At a dose of 10 μmol/L, forskolin induced PTP1D mRNA expression almost two times higher than control values. Conclusion: These data suggest that in human endometrial carcinomas, cAMP, EGF, and IGF-I may regulate the expression of PTP1D mRNA, which may, in turn, play a role in uncontrolled cell proliferation and neoplastic transformation.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68928/2/10.1177_107155769700400608.pd
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