723 research outputs found
Mass and Number and Its Chemical Composition Distribution of Particulate Matter in Different Microenvironments
Adverse health effects from exposure to air pollution are a global challenge and of widespread concern. Therefore, the present study attempted to pave the way in the study of indoor air pollution by coarse and fine particulate matter and picturesque its relation with the different indoor microenvironment. A campaign study was conducted in the city of Taj âAgra,â India in which different microenvironments were selected (i.e., offices, shops, and commercial centers). For each site, two different locations were chosen to examine the coarse particles (PM10 and PM5.0) and fine particles (PM2.5, PM1.0, PM0.5 and PM0.25) concentrations and metal concentration of Zn, Pb, Ni, Fe, Cr, Cd, Mg and Cu in PM2.5 and for their related health effects. The exposure factor and health risk assessment for carcinogenic effects due to heavy metal contaminants have also been calculated for adults working in different microenvironment by following the methodology prescribed by US EPA
On the cross-section of Dark Matter using substructure infall into galaxy clusters
We develop a statistical method to measure the interaction cross-section of
Dark Matter, exploiting the continuous minor merger events in which small
substructures fall into galaxy clusters. We find that by taking the ratio of
the distances between the galaxies and Dark Matter, and galaxies and gas in
accreting sub-halos, we form a quantity that can be statistically averaged over
a large sample of systems whilst removing any inherent line-of-sight
projections. In order to interpret this ratio as a cross-section of Dark Matter
we derive an analytical description of sub-halo infall which encompasses; the
force of the main cluster potential, the drag on a gas sub-halo, a model for
Dark Matter self-interactions and the resulting sub-halo drag, the force on the
gas and galaxies due to the Dark Matter sub-halo potential, and finally the
buoyancy on the gas and Dark Matter. We create mock observations from
cosmological simulations of structure formation and find that collisionless
Dark Matter becomes physically separated from X-ray gas by up to 20h^-1 kpc.
Adding realistic levels of noise, we are able to predict achievable constraints
from observational data. Current archival data should be able to detect a
difference in the dynamical behaviour of Dark Matter and standard model
particles at 6 sigma, and measure the total interaction cross-section sigma/m
with 68% confidence limits of +/- 1cm2g^-1. We note that this method is not
restricted by the limited number of major merging events and is easily extended
to large samples of clusters from future surveys which could potentially push
statistical errors to 0.1cm^2g^-1.Comment: 14 pages, 11 figure
Differential reproductive plasticity under thermal variability in a freshwater fish (Danio rerio)
publishedVersionPaid Open Acces
Differential reproductive plasticity under thermal variability in a freshwater fish (Danio rerio)
Human-driven increases in global mean temperatures are associated with concomitant increases in thermal variability. Yet, few studies have explored the impacts of thermal variability on fitness-related traits, limiting our ability to predict how organisms will respond to dynamic thermal changes. Among the myriad organismal responses to thermal variability, one of the most proximate to fitnessâand, thus, a population's ability to persistâis reproduction. Here, we examine how a model freshwater fish (Danio rerio) responds to diel thermal fluctuations that span the species's viable developmental range of temperatures. We specifically investigate reproductive performance metrics including spawning success, fecundity, egg provisioning and sperm concentration. Notably, we apply thermal variability treatments during two ontogenetic timepoints to disentangle the relative effects of developmental plasticity and reversible acclimation. We found evidence of direct, negative effects of thermal variability during later ontogenetic stages on reproductive performance metrics. We also found complex interactive effects of early and late-life exposure to thermal variability, with evidence of beneficial acclimation of spawning success and modification of the relationship between fecundity and egg provisioning. Our findings illuminate the plastic life-history modifications that fish may undergo as their thermal environments become increasingly variable.publishedVersio
Influence of Microenvironments and Personal Activities on Personal PM<sub>2.5</sub> Exposures among Children and Adults
Environmental issues are a major worldwide problem of significant concern. Due to the growing human population and advancement in every sector, the environmental related issues are multiplying in recent years. Scalable exposures assessments approach that captures personal exposure to particles for purposes of epidemiology are currently limited, but very valuable especially for a country like India. The high levels of indoor particulate matter and the apparent scale of its impact on the global burden of disease underline the importance of particulate as an environmental health risk and the need for monitoring them. Human exposure especially to fine particles can have significant harmful effects on the respiratory and cardiovascular system. To investigate daily exposure characteristics to PM2.5 with ambient concentrations in an urban environment, personal exposure measurements were conducted for different age groups of people residing in different indoor environments. To account for PM2.5 exposure and measurements personal environment monitors (PEM) and medium volume sampler APM 550 was used to measure PM2.5 concentration. On comparing the annual average PM2.5 concentration with National Ambient Air Quality and WHO standards the concentrations were found to be many folds higher for personal and ambient monitoring at homes, schools, and offices. Moreover, the questionnaire data study explains the fact that the health hazards experienced by occupants linked to various activity patterns pose a greater risk in different indoor environments as compared to outdoor environments. The presented research method and analysis can help develop environmental awareness in identifying these pollutants and can also help in elucidating these contaminants. A real understanding of these possible causes of airborne contaminant is crucial for selecting and developing suitable and effective control methods
Wormhole Cosmology and the Horizon Problem
We construct an explicit class of dynamic lorentzian wormholes connecting
Friedmann-Robertson-Walker (FRW) spacetimes. These wormholes can allow two-way
transmission of signals between spatially separated regions of spacetime and
could permit such regions to come into thermal contact. The cosmology of a
network of early Universe wormholes is discussed.Comment: 13 pages, in RevTe
Additive drug-specific and sex-specific risks associated with co-use of marijuana and tobacco during pregnancy: Evidence from 3 recent developmental cohorts (2003-2015).
BACKGROUND: Methodologic challenges related to the concomitant use (co-use) of substances and changes in policy and potency of marijuana contribute to ongoing uncertainty about risks to fetal neurodevelopment associated with prenatal marijuana use. In this study, we examined two biomarkers of fetal neurodevelopmental risk-birth weight and length of gestation-associated with prenatal marijuana use, independent of tobacco (TOB), alcohol (ALC), other drug use (OTH), and socioeconomic risk (SES), in a pooled sample (NâŻ=âŻ1191) derived from 3 recent developmental cohorts (2003-2015) with state-of-the-art substance use measures. We examined differential associations by infant sex, and multiplicative effects associated with co-use of MJ and TOB.
METHODS: Participants were mother-infant dyads with complete data on all study variables derived from Growing Up Healthy (nâŻ=âŻ251), Behavior and Mood in Babies and Mothers (Cohorts 1 and 2; nâŻ=âŻ315), and the Early Growth and Development Study (NâŻ=âŻ625). We estimated direct effects on birth weight and length of gestation associated with MJ, TOB, and co-use (MJ x TOB), using linear regression analysis in the full sample, and in male (nâŻ=âŻ654) and female (nâŻ=âŻ537) infants, separately.
RESULTS: Mean birth weight and length of gestation were 3277âŻg (SDâŻ=âŻ543) and 37.8âŻweeks (SDâŻ=âŻ2.0), respectively. Rates of prenatal use were as follows: any use, nâŻ=âŻ748 (62.8%); MJ use, nâŻ=âŻ273 (22.9%); TOB use, nâŻ=âŻ608 (51.0%); co-use of MJ and TOB, nâŻ=âŻ230 (19.3%); ALC use, nâŻ=âŻ464 (39.0%); and OTH use nâŻ=âŻ115 (9.7%.) For all infants, unique effects on birth weight were observed for any MJ use [B(SE)âŻ=âŻ-84.367(38.271), 95% C.I. -159.453 to -9.281, pâŻ=âŻ.028], any TOB use [B(SE)âŻ=âŻ-0.99.416(34.418), 95% C.I. -166.942 to -31.889, pâŻ=âŻ.004], and each cigarette/day in mean TOB use [B(SE)âŻ=âŻ-12.233(3.427), 95% C.I. -18.995 to -5.510, pâŻ\u3câŻ.001]. Additional effects of co-use on birth weight, beyond these drug-specific effects, were not supported. In analyses stratified by sex, while TOB use was associated with lower birth weight in both sexes, MJ use during pregnancy was associated with lower birth weight of male infants [B(SE)âŻ=âŻ-153.1 (54.20); 95% C.I. -259.5 to -46.7, pâŻ=âŻ.005], but not female infants [B(SE)âŻ=âŻ8.3(53.1), 95% C.I. -96.024 to 112.551, pâŻ=âŻ.876]. TOB, MJ, and their co-use were not associated with length of gestation.
CONCLUSIONS: In this sample, intrauterine co-exposure to MJ and TOB was associated with an estimated 18% reduction in birth weight not attributable to earlier delivery, exposure to ALC or OTH drugs, nor to maternal SES. We found evidence for greater susceptibility of male fetuses to any prenatal MJ exposure. Examination of dose-dependence in relationships found in this study, using continuous measures of exposure, is an important next step. Finally, we underscore the need to consider (a) the potential moderating influence of fetal sex on exposure-related neurodevelopmental risks; and (b) the importance of quantifying expressions of risk through subtle alterations, rather than dichotomous outcomes
Forum 2: The migrant climate: resilience, adaptation and the ontopolitics of mobility in the Anthropocene
While modernist or âtop-downâ, âcommand-and-controlâ approaches to climate and migration worked at the surface or ontic level of the redistribution of entities in time and space, resilience approaches call for a different approach to mobility (for an extensive discussion of resilience as a distinctive governance regime see, for example, Grove, 2018; Chandler, 2014). These discourses construct mobilities that are more transformative, in fact, ones that question traditional liberal modernist notions of time and space and of entities with fixed essences. These mobilities do not concern moving entities in space but rethinking mobility in relation to space. Mobility then becomes more a matter of changing the understandings and practices relating to spaces and entities than of moving things from one place to another. Becoming âmobileâ thus would apply to the development of capabilities or âresponse-abilitiesâ (Haraway, 2016: 2) to sense, adapt, recompose, repurpose and reimagine problems and possibilities; taking responses to crises beyond the static and binary conceptions of mobility and space epitomised by The Clash lyrics in the epigraph
The Recent Star Formation in NGC 6822: an Ultraviolet Study
We characterize the star formation in the low-metallicity galaxy NGC 6822
over the past few hundred million years, using GALEX far-UV (FUV, 1344-1786 A)
and near-UV (NUV, 1771-2831 A) imaging, and ground-based Ha imaging. From GALEX
FUV image, we define 77 star-forming (SF) regions with area >860 pc^2, and
surface brightness <=26.8 mag(AB)arcsec^-2, within 0.2deg (1.7kpc) of the
center of the galaxy. We estimate the extinction by interstellar dust in each
SF region from resolved photometry of the hot stars it contains: E(B-V) ranges
from the minimum foreground value of 0.22mag up to 0.66+-0.21mag. The
integrated FUV and NUV photometry, compared with stellar population models,
yields ages of the SF complexes up to a few hundred Myr, and masses from 2x10^2
Msun to 1.5x10^6 Msun. The derived ages and masses strongly depend on the
assumed type of interstellar selective extinction, which we find to vary across
the galaxy. The total mass of the FUV-defined SF regions translates into an
average star formation rate (SFR) of 1.4x10^-2 Msun/yr over the past 100 Myr,
and SFR=1.0x10^-2 Msun/yr in the most recent 10 Myr. The latter is in agreement
with the value that we derive from the Ha luminosity, SFR=0.008 Msun/yr. The
SFR in the most recent epoch becomes higher if we add the SFR=0.02 Msun/yr
inferred from far-IR measurements, which trace star formation still embedded in
dust (age <= a few Myr).Comment: Accepted for publication in ApJ, 21 pages, 6 figures, 3 table
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