29,030 research outputs found
Enhanced drag in pipe turbulent flow by an aqueous electrolyte: an electroviscous effect
Drag enhancement is reported for turbulent pipe flow of aqueous electrolyte solutions. No electroviscous effect was obtained with laminar flow. Nor was any unusual pressure drop observed for laminar or turbulent flow of non-electrolyte aqueous solutions such as sugar. An electroviscous theory was advanced that predicted the drag enhancement for a 1/1 electrolyte solution. The theory depended on consideration of Debye length
Incompressible states of negatively charged magneto-excitons
We study the system of up to four negatively charged magneto-excitons (X-'s)
in the spherical geometry, using the exact-diagonalization techniques. At low
energies, X-'s are bound and behave like charged particles without internal
dynamics. The pseudopotential describing X-:X- scattering is almost identical
to that of electrons and the low-lying few X- states correspond to the
few-electron states. The total angular momentum of the ground state depends on
the effective filling factor nu and vanishes at its special values. The analogs
to the Laughlin nu=1/3 state and the Jain nu=2/5 state of electrons are found.
The X- system is predicted to exhibit the fractional quantum Hall effect.Comment: RevTeX + 2 EPS figures formatted in the text with epsf.sty; to appear
in Physica
Effect of Socio-Demographics, Health-Related Problems, and Family Structure on Chronic Absenteeism Among Children
Purpose/Background: From 5 to 7.5 million school children are chronically absent, defined as missing â„15 days of school within a year. Students miss schools due to various reasons such as health, socioeconomic status, and environmental factors. We examined childâs health and behavior, family structure, and socio-demographics to understand chronic absenteeism.
Materials & Methods: The population included children ages 6 to 17 years from the Medical Expenditure Panel Survey (MEPS) years 2008-2013. Multivariable logistic regressions were used to identify the risk factors of chronic absenteeism, adjusting for the complex sampling design.
Results: Among socio-demographic variables, age â„14 years, race/ethnicity, lower-income family, public health insurance, US-born, and speaking English at home were associated with chronic absenteeism. Asians, Mexican Hispanics, and blacks have lower chronic absenteeism than whites. Among health-related variables, children using an inhaler for asthma, having behavioral problems, and less healthy than other children were more likely to be chronically absent. Among family variables, a smaller family size was a risk factor for chronic absenteeism.
Discussion/Conclusion: Asthma and behavioral problems were highly associated with chronic absenteeism. The identification of children at risk for chronic absenteeism will help the educational professionals identify the barriers to academic achievements and develop integrated educational interventions and policies to support disadvantaged children
The Origin of C IV Absorption Systems at Redshifts z<1---Discovery of Extended C IV Envelopes Around Galaxies
(Abridged) We report the discovery of extended CIV gaseous envelopes around
galaxies of a wide range of luminosity and morphological type. First, we show
that CIV absorption systems are strongly clustered around galaxies on velocity
scales of v < 250 km/s and impact parameter scales of rho < 100 h^{-1} kpc but
not on larger velocity or impact parameter scales. Next, adopting measurements
of galaxy properties presented in previous papers, we examine how properties of
the CIV absorption systems depend on properties of the galaxies. On the basis
of 14 galaxy and absorber pairs and 36 galaxies that do not produce
corresponding CIV absorption lines to within sensitive upper limits, we find
that: (1) Galaxies of a range of morphological type and luminosity appear to
possess extended CIV gaseous envelopes of radius R ~ 100 h^{-1} kpc, with
abrupt boundaries between the CIV absorbing and non-absorbing regions. (2) The
extent of CIV-absorbing gas around galaxies scales with galaxy B-band
luminosity as R \propto L_B^{0.5 +/- 0.1} but does not depend strongly on
galaxy surface brightness, redshift, or morphological type. And (3) the
covering factor of CIV clouds within ~ 100 h^{-1} kpc of galaxies is nearly
unity, but there is a large scatter in the mean number of clouds encountered
along the line of sight. The most significant implication of the study is that
galaxies of a wide range of luminosity and morphological type are surrounded by
chemically enriched gas that extends for at least ~ 100 h^{-1} kpc. We consider
various scenarios that may have produced metals at large galactic distance and
conclude that accreting satellites are most likely to be responsible for
chemically enriched gas at large galactic distances to regular looking
galaxies.Comment: 19 pages, 3 figures, to appear in ApJ, July 20 200
Oncologic Imaging
Imaging is an integral part of the multidisciplinary management of cancer. Radiographic techniques are indispensable for proper staging of cancers and evaluation of the response of tumors to treatment. A wide variety of imaging modalities is available to clinicians. This chapter in Cancer Concepts: A Guidebook for the Non-Oncologist will introduce the role of radiology in the diagnosis and treatment of cancer.https://escholarship.umassmed.edu/cancer_concepts/1017/thumbnail.jp
Human Papillomavirus (HPV) Vaccination Status Among University Freshmen in Hawaiâi
Purpose/Background: The HPV vaccine provides immunity against nine HPV strains that cause cancer and genital warts. It is recommended for 11 to 12 year olds, and catch-up immunization is recommended for females 13 to 26 years old and males 13 to 21 years old. College students represent an important population for HPV vaccination due to their increased risk for HPV infection. Despite the benefits of the HPV vaccine, its coverage rates are low in Hawaii. Hawaiâi is the home of two large universities on two islands that are representative of Hawaiâiâs populations, including Native Hawaiians, Filipinos, and Pacific Islanders. The purpose of this study was to assess the current HPV and HPV vaccine knowledge, barriers and beliefs among incoming Freshmen university students at University of Hawaiâi at MÄnoa and University of Hawaiâi at Hilo.
Materials & Methods: In 2016, 200 University of Hawaiâi at MÄnoa (UHM) and University of Hawaiâi at Hilo (UHH) Freshmen students responded to a survey that assessed their knowledge and awareness of HPV, the HPV vaccine, their current vaccination status, and barriers and motivators to vaccination. Descriptive statistics were used to summarize each survey variable first for all students and then separately for each campus.
Results: Overall 76% of Freshmen from both campuses heard of the HPV vaccine and 54% reported hearing it from their health care provider. Only 28% UHM and 23% UHH Freshmen students have received partial (1-2 shots) or completed doses of the HPV vaccine. For those who received the vaccine, 45% reported that they were told by their parent and 43% were told by their doctor. For the 147 students who did not receive the vaccine, 28% reported that they are still not sure to get it and 20% need more information. Their main reasons for not receiving the HPV vaccine were: their doctor did not mention the vaccine to him/her (44%), he/she never knew about the vaccine (18%), and they don\u27t know enough about the vaccine (17%).
Discussion/Conclusion: Although the HPV vaccine has been available for 13 years, young adults remain unvaccinated. Freshmen students reported that they are informed about the vaccine, but were not vaccinated because of the lack of parental and/or healthcare provider recommendation. With no active education campaigns in Hawaii promoting the HPV vaccine at college campuses, a first step to increasing vaccination rates is to develop a health education campaign to inform students of the HPV vaccine and its availability at campus clinics and neighboring pharmacies
How Do Consumers Use Nutrition Labels on Food Products in the United States?
This study examined how consumers use food labels in the United States. Based on the results from the cluster analysis, eight nutrition label questions from the Health and Diet Survey fell into 2 categories of label usage: for shopping or for dietary decisions. Survey respondents reported equal or more consideration of nutrition-label information for dietary choices than for shopping decisions in 2008 compared with prior survey years. Female consumers, frequent label users, well-educated, consumers aged 50 to 59, or consumers with any health issues were significantly more likely to use food labels for all kinds of purposes than their corresponding counterparts
Hybrid fuzzy and sliding-mode control for motorised tether spin-up when coupled with axial vibration
A hybrid fuzzy sliding mode controller is applied to the control of motorised tether spin-up coupled with an axial oscillation phenomenon. A six degree of freedom dynamic model of a motorised momentum exchange tether is used as a basis for interplanetary payload exchange. The tether comprises a symmetrical double payload configuration, with an outrigger counter inertia and massive central facility. It is shown that including axial elasticity permits an enhanced level of performance prediction accuracy and a useful departure from the usual rigid body representations, particularly for accurate payload positioning at strategic points. A special simulation program has been devised in MATLAB and MATHEMATICA for a given initial condition data case
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