FACTS Special Issue on Migration and Health

Migration is a global phenomenon involving hundreds of millions of people, with major social and economic impacts on migrants in their countries of origin and destination and on their communities. In the U.S., California is by far the most affected state by these population movements. The University of California Global Health Institute (UCGHI), Center of Expertise on Migration and Health (COEMH) is devoted to systematically studying the health consequences of global population movements and developing more effective strategies to address them. A key objective of the Center is to enhance educational opportunities related to migration and health. To do this, the Center implements graduate education, conducts research on immigrant and refugee communities, establishes distance education opportunities, and develops transnational collaborations. These activities provide a rich, real-world environment for training the next generation of leaders who will respond to emerging health issues related to migration. The Center’s annual Research Training Workshop is one such activity, resulting in rich discussions, cross-disciplinary interactions, and invaluable learning opportunities. This special issue on migration and health stems from the Research Training Workshop held on June 21-23, 2011, which was organized by COEMH. The workshop brought nineteen graduate students and postdoctoral fellows together in a multi-disciplinary setting to present their research and receive constructive feedback from University of California faculty members. Each paper presented in this special issue represents a unique issue related to migration and health.L'immigration est un phénomène mondial qui concerne des centaines de millions de personnes, et qui a des conséquences socio-économiques majeures sur les migrants dans leur pays d'origine et dans leur pays de destination, et également sur leurs communautés. Aux Etats-Unis, la Californie est de loin l'état le plus touché par ces mouvements de population. Le COEMH (Center of Expertise on Migration and Health) de l’UCGHI (University of California Global Health Institute), est spécialisé dans l'étude systématique des conséquences des mouvements de population sur la santé et dans l'élaboration de stratégies efficaces pour y remédier. L'un des objectifs clés du Centre est d'accroître les opportunités d'apprentissage liées à l'immigration et à la santé. Pour cela, le Centre met un œuvre un enseignement supérieur, conduit des recherches sur les communautés d'immigrants et de réfugiés, crée des opportunités d'enseignement à distance, et développe des collaborations transnationales. Ces activités constituent un environnement concret permettant de former la prochaine génération de dirigeants qui devra faire face aux problèmes de santé émergents liés à l'immigration. Le Research Training Workshop est l'une des initiatives annuelles du Centre. Il consiste en des débats approfondis, des interactions pluridisciplinaires et des opportunités d'apprentissage utiles. Ce numéro spécial consacré à l'immigration et à la santé découle du Research Training Workshop organisé par le COEMH du 21 au 23 juin 2011. Cet atelier a réuni dix-neuf étudiants diplômés et post-doctorants dans un contexte pluridisciplinaire qui ont présenté leurs travaux de recherche et reçu des commentaires constructifs de la part des membres de la faculté de l'Université de Californie. Chaque article de ce numéro spécial traite d'un sujet spécifique lié à l'immigration et à la santé.La migración es un fenómeno de escala mundial que involucra a cientos de millones de personas  y tiene un impacto social y económico tanto en los inmigrantes, como ensus países de origen y  destino, y en las comunidades en las que viven. En los Estados Unidos, el estado más afectado por estos movimientos de población es  California. El Centro de Expertos en Migración y Salud (COEMH por sus siglas en inglés) del Instituto de Salud Global de la Universidad de California (UCGHI por sus siglas en inglés) se dedica a realizar estudios sistemáticos sobre las consecuencias que estos  movimientos de población mundial tienen sobre la salud,  a fin de crear estrategias efectivas para abordarlos. Un objetivo clave del Centro es mejorar las oportunidades educativas relacionadas con la inmigración y la salud.  Para ello, el Centro imparte enseñanza universitaria, realiza estudios sobre las comunidades de inmigrantes y refugiados, crea oportunidades de educación a distancia y desarrolla colaboraciones transnacionales. Estas actividades proporcionan un ambiente rico en experiencias reales  para formar a la próxima generación de líderes que darán respuesta a los problemas de salud emergentes relacionados con la migración. Una de estas oportunidades que el Centro ofrece anualmente es el Taller de Formación e Investigación  que propicia profusos debates, e interacciones interdisciplinarias, además de valiosas oportunidades de aprendizaje. Este número especial sobre inmigración y salud nació a partir del Taller de Formación e Investigación celebrado del 21 al 23 de junio de 2011, organizado por COEMH. El taller reunió a 19 estudiantes de postgrado y becarios posdoctorales en un entorno multidisciplinario dónde pudieron presentar sus investigaciones y escuchar opiniones constructivas por parte del cuerpo de docentes de la Universidad de California. Cada trabajo presentado en este número especial representa un aspecto único relacionado con la migración y la salud

Improving on analyses of self-reported data in a large-scale health survey by using information from an examination-based survey

Common data sources for assessing the health of a population of interest include large-scale surveys based on interviews that often pose questions requiring a self-report, such as, ‘Has a doctor or other health professional ever told you that you have 〈 health condition of interest〉 ?’ or ‘What is your 〈 height/weight〉 ?’ Answers to such questions might not always reflect the true prevalences of health conditions (for example, if a respondent misreports height/weight or does not have access to a doctor or other health professional). Such ‘measurement error’ in health data could affect inferences about measures of health and health disparities. Drawing on two surveys conducted by the National Center for Health Statistics, this paper describes an imputation-based strategy for using clinical information from an examination-based health survey to improve on analyses of self-reported data in a larger interview-based health survey. Models predicting clinical values from self-reported values and covariates are fitted to data from the National Health and Nutrition Examination Survey (NHANES), which asks self-report questions during an interview component and also obtains clinical measurements during a physical examination component. The fitted models are used to multiply impute clinical values for the National Health Interview Survey (NHIS), a larger survey that obtains data solely via interviews. Illustrations involving hypertension, diabetes, and obesity suggest that estimates of health measures based on the multiply imputed clinical values are different from those based on the NHIS self-reported data alone and have smaller estimated standard errors than those based solely on the NHANES clinical data. The paper discusses the relationship of the methods used in the study to two-phase/two-stage/validation sampling and estimation, along with limitations, practical considerations, and areas for future research. Published in 2009 by John Wiley & Sons, Ltd.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65032/1/3809_ftp.pd

The Influence of the Degree of Heterogeneity on the Elastic Properties of Random Sphere Packings

The macroscopic mechanical properties of colloidal particle gels strongly depend on the local arrangement of the powder particles. Experiments have shown that more heterogeneous microstructures exhibit up to one order of magnitude higher elastic properties than their more homogeneous counterparts at equal volume fraction. In this paper, packings of spherical particles are used as model structures to computationally investigate the elastic properties of coagulated particle gels as a function of their degree of heterogeneity. The discrete element model comprises a linear elastic contact law, particle bonding and damping. The simulation parameters were calibrated using a homogeneous and a heterogeneous microstructure originating from earlier Brownian dynamics simulations. A systematic study of the elastic properties as a function of the degree of heterogeneity was performed using two sets of microstructures obtained from Brownian dynamics simulation and from the void expansion method. Both sets cover a broad and to a large extent overlapping range of degrees of heterogeneity. The simulations have shown that the elastic properties as a function of the degree of heterogeneity are independent of the structure generation algorithm and that the relation between the shear modulus and the degree of heterogeneity can be well described by a power law. This suggests the presence of a critical degree of heterogeneity and, therefore, a phase transition between a phase with finite and one with zero elastic properties.Comment: 8 pages, 6 figures; Granular Matter (published online: 11. February 2012

Overlapping confidence intervals or standard error intervals: What do they mean in terms of statistical significance?

We investigate the procedure of checking for overlap between confidence intervals or standard error intervals to draw conclusions regarding hypotheses about differences between population parameters. Mathematical expressions and algebraic manipulations are given, and computer simulations are performed to assess the usefulness of confidence and standard error intervals in this manner. We make recommendations for their use in situations in which standard tests of hypotheses do not exist. An example is given that tests this methodology for comparing effective dose levels in independent probit regressions, an application that is also pertinent to derivations of LC(50)s for insect pathogens and of detectability half-lives for prey proteins or DNA sequences in predator gut analysis

New Constraints on Cosmic Reionization from the 2012 Hubble Ultra Deep Field Campaign

Understanding cosmic reionization requires the identification and characterization of early sources of hydrogen-ionizing photons. The 2012 Hubble Ultra Deep Field (UDF12) campaign has acquired the deepest infrared images with the Wide Field Camera 3 aboard Hubble Space Telescope and, for the first time, systematically explored the galaxy population deep into the era when cosmic microwave background (CMB) data indicate reionization was underway. The UDF12 campaign thus provides the best constraints to date on the abundance, luminosity distribution, and spectral properties of early star-forming galaxies. We synthesize the new UDF12 results with the most recent constraints from CMB observations to infer redshift-dependent ultraviolet (UV) luminosity densities, reionization histories, and electron scattering optical depth evolution consistent with the available data. Under reasonable assumptions about the escape fraction of hydrogen-ionizing photons and the intergalactic medium clumping factor, we find that to fully reionize the universe by redshift z ~ 6 the population of star-forming galaxies at redshifts z ~ 7-9 likely must extend in luminosity below the UDF12 limits to absolute UV magnitudes of M UV ~ –13 or fainter. Moreover, low levels of star formation extending to redshifts z ~ 15-25, as suggested by the normal UV colors of z ≃ 7-8 galaxies and the smooth decline in abundance with redshift observed by UDF12 to z ≃ 10, are additionally likely required to reproduce the optical depth to electron scattering inferred from CMB observations

Ecological Remediation Using Bacterial, Fungal, and Plant Microcosms: An Effective Solution for Bunker C Crude Oil Contamination in Waterways

Factory legacy pollutants are an increasing concern for waterways as old infrastructure deteriorates and contaminates nearby environments. The Fisherville Mill in Grafton, Massachusetts, USA exemplifies this problem since it has now fallen into disrepair and is leaking Bunker C crude oil into the adjoining Blackstone River, a third order stream. Our research examines how effectively an ecologically engineered system (EES), consisting of anaerobic bacteria environments, fungal microcosms, and aquatic plant environments, can break down petroleum hydrocarbons, specifically aliphatic and polycyclic aromatic hydrocarbons (PAH), in this river environment. Our testing protocol involved taking water samples before and after each filtration stage monthly from June through October 2012. Water samples were analyzed at the Brown University Superfund Research Lab using mass spectrometry to determine aliphatic and PAH concentrations. Post-treatment aliphatic oil concentrations were significantly different from baseline concentrations (p=0.005), with an average reduction of 95.2%. Post-treatment PAH concentrations were also significantly different from baseline concentrations (p=0.001), with an average reduction of 91%. We conclude that this EES provided effective treatment for Bunker C crude oil, even though some filtration stages did not achieve their intended objectives. This type of filtration arrangement might be scaled up for use in larger remediation efforts regarding Bunker C crude oil

Keck Spectroscopy of Faint 3<z<8 Lyman Break Galaxies:- Evidence for a Declining Fraction of Emission Line Sources In the Redshift Range 6<z<8

Using deep Keck spectroscopy of Lyman break galaxies selected from infrared imaging data taken with WFC3/IR onboard the Hubble Space Telescope, we present new evidence for a reversal in the redshift-dependent fraction of star forming galaxies with detectable Lyman alpha emission in the redshift range 6.3 < z < 8.8. Our earlier surveys with the DEIMOS spectrograph demonstrated a significant increase with redshift in the fraction of line emitting galaxies over the interval 4 < z < 6, particularly for intrinsically faint systems which dominate the luminosity density. Using the longer wavelength sensitivities of LRIS and NIRSPEC, we have targeted 19 Lyman break galaxies selected using recent WFC3/IR data whose photometric redshifts are in the range 6.3 < z < 8.8 and which span a wide range of intrinsic luminosities. Our spectroscopic exposures typically reach a 5-sigma sensitivity of < 50 A for the rest-frame equivalent width (EW) of Lyman alpha emission. Despite the high fraction of emitters seen only a few hundred million years later, we find only 2 convincing and 1 possible line emitter in our more distant sample. Combining with published data on a further 7 sources obtained using FORS2 on the ESO VLT, and assuming continuity in the trends found at lower redshift, we discuss the significance of this apparent reversal in the redshift-dependent Lyman alpha fraction in the context of our range in continuum luminosity. Assuming all the targeted sources are at their photometric redshift and our assumptions about the Lyman alpha EW distribution are correct, we would expect to find so few emitters in less than 1% of the realizations drawn from our lower redshift samples. Our new results provide further support for the suggestion that, at the redshifts now being probed spectroscopically, we are entering the era where the intergalactic medium is partially neutral.Comment: 8 pages, 5 figures, Accepted to ApJ 10/1/1

Generation of Porous Particle Structures using the Void Expansion Method

The newly developed "void expansion method" allows for an efficient generation of porous packings of spherical particles over a wide range of volume fractions using the discrete element method. Particles are randomly placed under addition of much smaller "void-particles". Then, the void-particle radius is increased repeatedly, thereby rearranging the structural particles until formation of a dense particle packing. The structural particles' mean coordination number was used to characterize the evolving microstructures. At some void radius, a transition from an initially low to a higher mean coordination number is found, which was used to characterize the influence of the various simulation parameters. For structural and void-particle stiffnesses of the same order of magnitude, the transition is found at constant total volume fraction slightly below the random close packing limit. For decreasing void-particle stiffness the transition is shifted towards a smaller void-particle radius and becomes smoother.Comment: 9 pages, 8 figure