Thermally induced oscillations in fluid flow

Theoretical investigation distinguishes the various mechanisms responsible for oscillations of pressure, temperature, and flow velocity, derives a quantitative description of the most troublesome mechanisms, and develops a capability to predict the occurrence of unstable flow

In Her Own Words: A Qualitative Case Study of Foster Care, Adoption and Independent Living

This is a biographical account of a young lady who was involved with the child welfare system for eleven years. “Jill” entered foster care when she was eight years old. She was adopted by her foster parents and re-abused as a young adolescent by her adoptive father. Jill re-entered foster care, experiencing several foster homes, caseworkers and counselors. This year Jill Is one of 20,000 foster children who will assume independence from the child welfare system. The author utilizes a qualitative method of case reporting. Interviews were conducted with Jill, former caseworkers, foster parents and therapists. In addition, a record analysis was conducted on her case file. The study is presented in the voice of Jill and others interviewed. Her life experiences are described in detail. Jill gives recommendations to improve the foster care system. Existing literature is utilized to compare Jill’s experience with other findings. Implications for future social work practice and research are discussed

ON THE PROBLEM OF LIQUID ENTRAINMENT

THe problem of liquid entrainmment by a gas phase is considered with the purpose of gathering, presentinf, and correlating available information which may be useful for predicting the liquid carry-over in a boiling water reactor at high pressure. Correlations which predict water carryover as a function of pressure, of the height of the vapor dome, and of the vapor mass flow rate are presented and discussed. Because entrainment depends upon the hydrodynamic conditions and upon the expansion of a two-phase bubbling mixture, the transportation 0f vapor through such mixtures is also discussed. Equations which relate the volumetric vapor fraction to the reduced (superficial) vapor velocity in bubbling at high pressures are presented, and some inconsistencies are noted. Experimental data and correlations which predict the location of the liquid-vapor interface in bubbling at high pressures are also givna. Experimental data on water carry-over at high pressures reported in the literature are summarized. The problems of drop formation for bursting bubbles and of drop ballistics are discussed together with some analytical formulations of the entrainment problem. The bibliography may prove useful as a source of additional information on the problems of carry- over, corrosion and on the purity of steam and of water at high pressures. (auth

Diabetes and kidney cancer: A direct or indirect association?

A positive association between diabetes and kidney cancer has been reported in several investigations, but it is unclear whether diabetes or its complications account for this association. Recent advances in estimating direct associations may be useful for elucidating the association between diabetes and kidney cancer. Therefore, we performed a case-control analysis to evaluate whether the direct association between diabetes and kidney cancer is the primary concern in this exposure-outcome relation. Discharge data (with International Classification of Diseases – 9 codes) from 2001 for hospitals throughout Florida were used to construct a case-control population of inpatients aged ≥45 years. Cases (n=1,909) were inpatients with malignant kidney cancer and controls (n=6,451) were inpatients with motor vehicle injuries. Diabetes status was ascertained for cases and controls. Covariates that required adjustment to estimate the total (age, gender, ethnicity, obesity, and smoking) and direct (age, gender, ethnicity, obesity, smoking, hypertension, and kidney disease) associations were identified in a directed acyclic graph. Binary logistic regression was used to estimate the adjusted total and direct odds ratios (ORs) and corresponding 95% confidence intervals (CIs) of kidney cancer for diabetics. The odds of kidney cancer were higher for inpatients with diabetes than inpatients without diabetes when estimating the total association (OR=1.27, 95%CI: 1.10, 1.47) but attenuated when estimating the direct association (OR=1.08, 95%CI: 0.93, 1.25). Our findings provide preliminary insight that the direct association between diabetes and kidney cancer may not be the primary concern in this exposure-outcome relation; indirect pathways (i.e. diabetic complications) may have greater influence on this relation. A similar analysis using longitudinal data with appropriately measured covariates may provide more definitive conclusions and could have implications for kidney cancer prevention among diabetics

Acceleration Profiles and Processing Methods for Parabolic Flight

Parabolic flights provide cost-effective, time-limited access to "weightless" or reduced gravity conditions experienced in space or on planetary surfaces, e.g. the Moon or Mars. These flights facilitate fundamental research - from materials science to space biology - and testing/validation activities that support and complement infrequent and costly access to space. While parabolic flights have been conducted for decades, reference acceleration profiles and processing methods are not widely available - yet are critical for assessing the results of these activities. Here we present a method for collecting, analyzing, and classifying the altered gravity environments experienced during a parabolic flight. We validated this method using a commercially available accelerometer during a Boeing 727-200F flight with $20$ parabolas. All data and analysis code are freely available. Our solution can be easily integrated with a variety of experimental designs, does not depend upon accelerometer orientation, and allows for unsupervised and repeatable classification of all phases of flight, providing a consistent and open-source approach to quantifying gravito-intertial accelerations (GIA), or $g$ levels. As academic, governmental, and commercial use of space increases, data availability and validated processing methods will enable better planning, execution, and analysis of parabolic flight experiments, and thus, facilitate future space activities.Comment: Correspondence to C.E. Carr ([email protected]). 15 pages, 4 figures, 3 supplemental figures. Code: https://github.com/CarrCE/zerog, Dataset: https://osf.io/nk2w4

Inferring Causal Relationships Between Risk Factors and Outcomes from Genome-Wide Association Study Data.

An observational correlation between a suspected risk factor and an outcome does not necessarily imply that interventions on levels of the risk factor will have a causal impact on the outcome (correlation is not causation). If genetic variants associated with the risk factor are also associated with the outcome, then this increases the plausibility that the risk factor is a causal determinant of the outcome. However, if the genetic variants in the analysis do not have a specific biological link to the risk factor, then causal claims can be spurious. We review the Mendelian randomization paradigm for making causal inferences using genetic variants. We consider monogenic analysis, in which genetic variants are taken from a single gene region, and polygenic analysis, which includes variants from multiple regions. We focus on answering two questions: When can Mendelian randomization be used to make reliable causal inferences, and when can it be used to make relevant causal inferences? Expected final online publication date for the Annual Review of Genomics and Human Genetics Volume 19 is August 31, 2018. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates

Hydrodynamic Aspects of Boiling Heat Transfer

A study concerned with the determination of the limiting hydrodynamic conditions which characterize nucleate and transitional boiling was conducted. The critical heat flux and the minimum heat flux are derived from these hydrodynamic limits. Results of investigations of nucleate boilin g are discussed and the theory of bubble growth is extended to include the effect of non-uniform temperature fields. An equation is derived for the product bubble diameter times frequency of bubble emission, and data showing that the diameter of nucleating cavities can he related to the heat flux density and superheat difference are presented. (J.R.D.