Cumulative Risk and a Call for Action in Environmental Justice Communities

Health disparities, social inequalities, and environmental injustice cumulatively affect individual and community vulnerability and overall health; yet health researchers, social scientists and environmental scientists generally study them separately. Cumulative risk assessment in poor, racially segregated, economically isolated and medically underserved communities needs to account for their multiple layers of vulnerability, including greater susceptibility, greater exposure, less preparedness to cope, and less ability to recover in the face of exposure. Recommendations for evidence-based action in environmental justice communities include: reducing pollution in communities of highest burden; building on community resources; redressing inequality when doing community-based research; and creating a screening framework to identify communities of greatest risk

Langevin Equation for the Rayleigh model with finite-ranged interactions

Both linear and nonlinear Langevin equations are derived directly from the Liouville equation for an exactly solvable model consisting of a Brownian particle of mass $M$ interacting with ideal gas molecules of mass $m$ via a quadratic repulsive potential. Explicit microscopic expressions for all kinetic coefficients appearing in these equations are presented. It is shown that the range of applicability of the Langevin equation, as well as statistical properties of random force, may depend not only on the mass ratio $m/M$ but also by the parameter $Nm/M$, involving the average number $N$ of molecules in the interaction zone around the particle. For the case of a short-ranged potential, when $N\ll 1$, analysis of the Langevin equations yields previously obtained results for a hard-wall potential in which only binary collisions are considered. For the finite-ranged potential, when multiple collisions are important ($N\gg 1$), the model describes nontrivial dynamics on time scales that are on the order of the collision time, a regime that is usually beyond the scope of more phenomenological models.Comment: 21 pages, 1 figure. To appear in Phys. Rev.

A Physical Interpretation of Stagnation Pressure and Enthalpy Changes in Unsteady Flow

This paper provides a physical interpretation of the mechanism of stagnation enthalpy and stagnation pressure changes in turbomachines due to unsteady flow, the agency for all work transfer between a turbomachine and an inviscid fluid. Examples are first given to illustrate the direct link between the time variation of static pressure seen by a given fluid particle and the rate of change of stagnation enthalpy for that particle. These include absolute stagnation temperature rises in turbine rotor tip leakage flow, wake transport through downstream blade rows, and effects of wake phasing on compressor work input. Fluid dynamic situations are then constructed to explain the effect of unsteadiness, including a physical interpretation of how stagnation pressure variations are created by temporal variations in static pressure; in this it is shown that the unsteady static pressure plays the role of a time-dependent body force potential. It is further shown that when the unsteadiness is due to a spatial nonuniformity translating at constant speed, as in a turbomachine, the unsteady pressure variation can be viewed as a local power input per unit mass from this body force to the fluid particle instantaneously at that point

Disentangling jet and disc emission from the 2005 outburst of XTE J1118+480

The black hole X-ray transient, XTE J1118+480, has now twice been observed in outburst - 2000 and 2005 - and on both occasions remained in the low/hard X-ray spectral state. Here we present radio, infrared, optical, soft X-ray and hard X-ray observations of the more recent outburst. We find that the lightcurves have very different morphologies compared with the 2000 event and the optical decay is delayed relative to the X-ray/radio. We attribute this lesser degree of correlation to contributions of emission from multiple components, in particular the jet and accretion disc. Whereas the jet seemed to dominate the broadband spectrum in 2000, in 2005 the accretion disc seems to be more prominent and we use an analysis of the lightcurves and spectra to distinguish between the jet and disc emission. There also appears to be an optically thin component to the radio emission in the 2005 data, possibly associated with multiple ejection events and decaying as the outburst proceeds. These results add to the discussion that the term "low/hard state'" covers a wider range of properties than previously thought, if it is to account for XTE J1118+480 during these two outbursts.Comment: Accepted for publication in MNRA

A DNA delivery system targeting dendritic cells for use in immunization against malaria: a rodent model

DNA-based vaccination has emerged as a promising method of immunisation since the first demonstration of this technology. Improving the antibody responses is desirable for the protective efficacy and hence broad application of these vaccines. We examined the immunogenicity of a Plasmodium-based DNA vaccine that was targeted to antigen presenting cells by fusion to CTLA4. Fusion proteins comprising the extra-cellular domain of CTLA4, the hinge, CH2 and CH3 domains of human IgG1 and MSP-1 gene fragments were expressed in COS-7 cells. Three of the secreted proteins containing the mouse homologue of CTLA4 were shown to bind differently to the human B7-1 molecule expressed on THP-1 cells. Competition binding assays for two fusion proteins showed that binding was specific. When C57BL/6 mice were immunized with plasmids encoding the fusion proteins, antibodies against two denatured and one non-denatured MSP-1 gene fragments were successfully induced. The usefulness of this strategy in future studies of immunisaton against human malaria is discussed. Keywords: malaria, PbMSP-1, DNA vaccine, dendritic cells, rodent model Tanzania Health Research Bulletin Vol. 7(3) 2005: 142-14

Measured and Calculated Dynamic Response of Rock-Fill Dam

The U.S. Army Corps of Engineers recently completed a seismic stability assessment of the Ririe Darn and Reservoir Project located near Idaho Falls, Idaho. Ririe Darn is an earth- and rockfill darn with a central impervious core constructed between 1966 and 1975 in a narrow canyon of Willow Creek. A geologic and seismologic study indicated that the controlling maximum credible earthquake (MCE} is a Magnitude 7.5 earthquake at a distance of 8 km from the darn. The seismic stability analysis included a dynamic response analysis of the darn using two-dimensional finite element procedures. Empirical relations derived from the observed response and analyses of other darns in narrow canyons were used to develop adjustment factors to correct natural frequencies, dynamic shear stresses, and peak accelerations for three-dimensional (3-D} effects. The October 28, 1983 Mt. Borah Earthquake triggered five strong-motion instruments installed at the crest, left abutment, downstream toe, and outlet tower of Ririe Darn. The epicentral distance to the darn was 179 km. The peak horizontal accelerations recorded at the crest and at the abutment were 0.05 g and 0.02 g, respectively. The accelerogram recorded by the instrument station at the abutment was used to calculate the dynamic response of the darn during the earthquake. From this analysis, the finite element model and the soil parameters were calibrated to best represent the 3-D dynamic response of the darn. After consideration of 3-D effects, the calculated response of the darn using soil properties derived from in-situ and laboratory measurements was in good agreement with the measured response during the 1983 Mt. Borah earthquake. These results indicate that when properly applied, currently available methods to determine soil properties for the dynamic response analysis of embankment darns including in-situ measurements, can provide properties in good agreement with those back-calculated from the observed response of darns

Distribution and abundance of fish and crayfish in a Waikato stream in relation to basin area

The aim of this study was to relate the longitudinal distribution of fish and crayfish to increasing basin area and physical site characteristics in the Mangaotama Stream, Waikato region, North Island, New Zealand. Fish and crayfish were captured with two-pass removal electroshocking at 11 sites located in hill-country with pasture, native forest, and mixed land uses within the 21.6 km2 basin. Number of fish species and lineal biomass of fish increased with increasing basin area, but barriers to upstream fish migration also influenced fish distribution; only climbing and non-migratory species were present above a series of small waterfalls. Fish biomass increased in direct proportion to stream width, suggesting that fish used much of the available channel, and stream width was closely related to basin area. Conversely, the abundance of crayfish was related to the amount of edge habitat, and therefore crayfish did not increase in abundance as basin area increased. Densities of all fish species combined ranged from 17 to 459 fish 100 m-2, and biomass ranged from 14 to 206 g m-2. Eels dominated the fish assemblages, comprising 85-100% of the total biomass; longfinned eels the majority of the biomass at most sites. Despite the open access of the lower sites to introduced brown trout, native species dominated all the fish communities sampled

Constraining the nature of the accreting binary in CXOGBS J174623.5-310550

We report optical and infrared observations of the X-ray source CXOGBS J174623.5-310550. This Galactic object was identified as a potential quiescent low-mass X-ray binary accreting from an M-type donor on the basis of optical spectroscopy and the broad Halpha emission line. The analysis of X-shooter spectroscopy covering 3 consecutive nights supports an M2/3-type spectral classification. Neither radial velocity variations nor rotational broadening is detected in the photospheric lines. No periodic variability is found in I- and r'-band light curves. We derive r' = 20.8, I = 19.2 and Ks = 16.6 for the optical and infrared counterparts with the M-type star contributing 90% to the I-band light. We estimate its distance to be 1.3-1.8 kpc. The lack of radial velocity variations implies that the M-type star is not the donor star in the X-ray binary. This could be an interloper or the outer body in a hierarchical triple. We constrain the accreting binary to be a < 2.2 hr orbital period eclipsing cataclysmic variable or a low-mass X-ray binary lying in the foreground of the Galactic Bulge.Comment: (9 pages, 5 figures, accepted for publication in MNRAS

Correlated X-ray and Optical Variability in V404 Cyg in Quiescence

We report simultaneous X-ray and optical observations of V404 Cyg in quiescence. The X-ray flux varied dramatically by a factor of >20 during a 60ks observation. X-ray variations were well correlated with those in Halpha, although the latter include an approximately constant component as well. Correlations can also be seen with the optical continuum, although these are less clear. We see no large lag between X-ray and optical line variations; this implies they are causally connected on short timescales. As in previous observations, Halpha flares exhibit a double-peaked profile suggesting emission distributed across the accretion disk. The peak separation is consistent with material extending outwards to at least the circularization radius. The prompt response in the entire Halpha line confirms that the variability is powered by X-ray (and/or EUV) irradiation.Comment: 5 pages; Accepted for publication in the Astrophysical Journal Letter