Constraining the strength of Dark Matter Interactions from Structure Formation

We discuss the damping of primordial dark matter fluctuations, taking into account explicitly the interactions of dark matter - whatever their intensity - both with itself and with other particle species. Relying on a general classification of dark matter particle candidates, our analysis provides, from structure formation, a new set of constraints on the dark matter particle mass and interaction rates (in particular with photons and neutrinos). This determines up to which cross sections the dark matter interactions may effectively be disregarded, and when they start playing an essential role, either through collisional damping or through an enhancement of the free-streaming scale. It leads us to extend the notions of Cold, Warm and Hot Dark Matter scenarios when dark matter interactions are no longer taken to be negligible. It also suggests the possibility of new scenarios of Collisional Warm Dark Matter, with moderate damping induced by dark matter interactions.Comment: 12 pages. Invited talk at DARK 2002, 4th Int. Conf. on Dark Matter in Astro and Particle Physics, Cape Town, Feb. 200

Differential Lead Accumulation in Brassica juncea, Brassica rapa, and Lactuca sativa and Evaluation of Ground Level Barriers to Prevent Lead Contamination of Produce Grown in Raised Beds

High lead (Pb) contamination of soils is a threat to human health. Urban area soils are frequently contaminated with lead from settling of gasoline exhaust, brake dust, and lead paint on homes, old playground equipment, etc. Exposure to soil-lead occurs by ingestion or inhalation and poses an elevated risk for young children. Indirect ingestion can occur through the food chain through activities such as growing certain vegetables with an ability to tolerate and accumulate lead in edible tissues. Many university extension systems recommend growing vegetables in raised beds as a reasonable reduced risk option for avoiding lead accumulation in garden vegetables particularly leafy greens and root vegetables. However, limited research outlines the efficacy of specific raised bed practices in excluding lead from the initially uncontaminated planting space. To address the soil-lead exposure pathway via garden produce, this study evaluates differential uptake of lead in common cool season vegetable crops and supplements gaps in the literature pertaining to raised-bed garden practices in lead contaminated areas. Three species of leafy green vegetables were grown in soil-less media contaminated at 0, 500, 1000, and 2000 ppm Pb to observe plant growth patterns and accumulation in contaminated raised bed conditions. Findings suggest minimal observations of toxic effects on growth and variable lead accumulation above threshold contaminant levels. Simulated raised beds were subsequently constructed to evaluate barriers placed at the interface between contaminated soil and the base of the uncontaminated raised bed soil. The resulting data suggests that neoprene rubber sheeting does not exclude lead from the raised bed

Cosmological Evolution of the Universe Neutral Gas Mass Measured by Quasar Absorption Systems

The cosmological evolution of neutral hydrogen is an efficient way of tracing structure formation with redshift. It indicates the rate of evolution of gas into stars and hence the gas consumption and rate star formation history of the Universe. In measuring HI, quasar absorbers have proven to be an ideal tool and we use observations from a recent survey for high-redshift quasar absorption systems together with data gathered from the literature to measure the cosmological comoving mass density of neutral gas. This paper assumes Omega_M=0.3, Omega_lambda=0.7 and h=0.65.Comment: 3 pages, 2 figures. To appear in the proceedings of the "Cosmic Evolution" conference, held at l'Institut d'Astrophysique de Paris, November 13-17, 200

A Homogeneous Sample of Sub-DLAs IV: Global Metallicity Evolution

An accurate method to measure the abundance of high-redshift galaxies consists in the observation of absorbers along the line of sight toward a background quasar. Here, we present abundance measurements of 13 z>3 sub-Damped Lyman-alpha Systems (quasar absorbers with HI column density 19 < log N(HI) < 20.3 cm^-2) based on the high resolution observations with VLT UVES spectrograph. These observations more than double the metallicity information for sub-DLAs previously available at z>3. This new data, combined with other sub-DLA measurements from the literature, confirm the stronger metallicity redshift evolution than for the classical Damped Lyman-alpha absorbers. Besides, these observations are used to compute for the first time the fraction of gas ionised from photo-ionisation modelling in a sample of sub-DLAs. Based on these results, we calculate that sub-DLAs contribute no more than 6% of the expected amount of metals at z~2.5. We therefore conclude that even if sub-DLAs are found to be more metal-rich than classical DLAs, they are insufficient to close the so-called ``missing metals problem''.Comment: 30 figures, 24 tables. Accepted for publication in MNRA

Role of tropical Pacific SSTs in global medieval hydroclimate: A modeling study

The role of tropical Pacific SSTs in driving global medieval hydroclimate is assessed. Using fossil coral records from Palmyra Atoll, tropical Pacific sea surface temperature (SST) boundary conditions are derived for the period 1320-1462 A.D. These boundary conditions consist of La Niña-like mean state conditions in the tropical Pacific with inter-annual and decadal variability about that altered state. The reconstructed SSTs in the tropical Pacific are used to force a 16 member ensemble of atmospheric general circulation model (AGCM) simulations, coupled to a one layer ocean model outside of the tropical Pacific. The AGCM simulations of medieval climate are compared with modern climate simulations for the period 1856-2005 A.D. and are shown to reproduce many aspects of medieval hydroclimate found in paleo-proxy records for much of the Western Hemisphere, northern Eurasia, and the northern tropics. These results suggest that many features of global medieval hydroclimate changes can be explained by changes in tropical Pacific SSTs, though the potential role for other oceans is also discussed

Utilizing the Boston Syncope Observation Management Pathway to Reduce Hospital Admission and Decrease Adverse Outcomes

Introduction: In an age of increasing scrutiny of each hospital admission, emergency department (ED) observation has been identified as a low-cost alternative. Prior studies have shown admission rates for syncope in the United States to be as high as 70%. However, the safety and utility of substituting ED observation unit (EDOU) syncope management has not been well studied. The objective of this study was to evaluate the safety of EDOU for the management of patients presenting to the ED with syncope and its efficacy in reducing hospital admissions. Methods: This was a prospective before-and-after cohort study of consecutive patients presenting with syncope who were seen in an urban ED and were either admitted to the hospital, discharged, or placed in the EDOU. We first performed an observation study of syncope management and then implemented an ED observation-based management pathway. We identified critical interventions and 30-day outcomes. We compared proportions of admissions and adverse events rates with a chisquared or Fisher’s exact test. Results: In the “before” phase, 570 patients were enrolled, with 334 (59%) admitted and 27 (5%) placed in the EDOU; 3% of patients discharged from the ED had critical interventions within 30 days and 10% returned. After the management pathway was introduced, 489 patients were enrolled; 34% (p\u3c0.001) of pathway patients were admitted while 20% were placed in the EDOU; 3% (p=0.99) of discharged patients had critical interventions at 30 days and 3% returned (p=0.001). Conclusion: A focused syncope management pathway effectively reduces hospital admissions and adverse events following discharge and returns to the ED. [West J Emerg Med. 2019;20(2)250–255.

Dollar Estimates of Feral Hog Damage to Agriculture in Louisiana (Research Information Sheet #113)

A study of feral hog activity and damage in Louisiana. Data were gathered from Louisiana farmers. The study results show that feral hogs caused at least $30 million in damage to crops on Louisiana farms in 2013. The publication includes maps and tables.https://digitalcommons.lsu.edu/agcenter_researchinfosheets/1002/thumbnail.jp

Abnormal development of forebrain midline glia and commissural projections in Nfia knock-out mice

Nuclear factor I (NFI) genes are expressed in multiple organs throughout development (Chaudhry et al., 1997; for review, see Gronostajski, 2000). All four NFI genes are expressed in embryonic mouse brain, with Nfia, Nfib, and Nfix being expressed highly in developing cortex (Chaudhry et al., 1997). Disruption of the Nfia gene causes agenesis of the corpus callosum (ACC), hydrocephalus, and reduced GFAP expression (das Neves et al., 1999). Three midline structures, the glial wedge, glia within the indusium griseum, and the glial sling are involved in development of the corpus callosum (Silver et al., 1982; Silver and Ogawa, 1983; Shu and Richards, 2001). Because Nfia(-/-) mice show glial abnormalities and ACC, we asked whether defects in midline glial structures occur in Nfia(-/-) mice. NFI-A protein is expressed in all three midline populations. In Nfia(-/-) mice sling cells are generated but migrate abnormally into the septum and do not form a sling. Glia within the indusium griseum and the glial wedge are greatly reduced or absent and consequently Slit2 expression is also reduced. Although callosal axons approach the midline, they fail to cross and extend aberrantly into the septum. The hippocampal commissure is absent or reduced, whereas the ipsilaterally projecting perforating axons (Hankin and Silver, 1988; Shu et al., 2001) appear relatively normal. These results support an essential role for midline glia in callosum development and a role for Nfia in the formation of midline glial structures