Siena College

About: Siena College is a education organization based out in Albany, New York, United States. It is known for research contribution in the topics: Galaxy & Redshift. The organization has 563 authors who have published 1291 publications receiving 31519 citations. The organization is also known as: St. Bernadine of Siena College.

Fast Plasma Investigation for Magnetospheric Multiscale

Abstract: The Fast Plasma Investigation (FPI) was developed for flight on the Magnetospheric Multiscale (MMS) mission to measure the differential directional flux of magnetospheric electrons and ions with unprecedented time resolution to resolve kinetic-scale plasma dynamics. This increased resolution has been accomplished by placing four dual 180-degree top hat spectrometers for electrons and four dual 180-degree top hat spectrometers for ions around the periphery of each of four MMS spacecraft. Using electrostatic field-of-view deflection, the eight spectrometers for each species together provide 4pi-sr field-of-view with, at worst, 11.25-degree sample spacing. Energy/charge sampling is provided by swept electrostatic energy/charge selection over the range from 10 eV/q to 30000 eV/q. The eight dual spectrometers on each spacecraft are controlled and interrogated by a single block redundant Instrument Data Processing Unit, which in turn interfaces to the observatory’s Instrument Suite Central Instrument Data Processor. This paper describes the design of FPI, its ground and in-flight calibration, its operational concept, and its data products.

Pulsed resources and community dynamics of consumers in terrestrial ecosystems

Abstract: . Accordingto this framework, populations oc-cupy positions in a food web andtheir abundance or biomass canbe controlled by populations athigher trophic levels (e.g. top-down effects of predators on prey),lower trophic levels (e.g. bottom-up effects of biotic resources onconsumers) or the same level(more traditional competitive in-teractions). The top-down bottom-up approach is sympathetic to thenotion that interactions betweenpopulations might be either direct(e.g. a predator controlling preydensity) or indirect (e.g. a primaryproducer enhancing a parasitoidpopulation by increasing popu-lation growth of a herbivore host).Recently, temporal fluctuations in the strengths of inter-actions among species have been of great interest to ecolo-gists

Biodiversity and disease risk : The case of Lyme disease

Abstract: Utilitarian arguments concerning the value of biodiversity often include the benefits of animals, plants, and microbes as sources of medicines and as laboratory models of disease. The concept that species di- versity per se may influence risk of exposure to disease has not been well developed, however. We present a conceptual model of how high species richness and evenness in communities of terrestrial vertebrates may re- duce risk of exposure to Lyme disease, a spirochetal ( Borrelia burgdorferi ) disease transmitted by ixodid tick vectors. Many ticks never become infected because some hosts are highly inefficient at transmitting spirochete infections to feeding ticks. In North America, the most competent reservoir host for the Lyme disease agent is the white-footed mouse ( Peromyscus leucopus ), a species that is widespread and locally abundant. We suggest that increases in species diversity within host communities may dilute the power of white-footed mice to in- fect ticks by causing more ticks to feed on inefficient disease reservoirs. High species diversity therefore is ex- pected to result in lower prevalence of infection in ticks and consequently in lower risk of human exposure to Lyme disease. Analyses of states and multistate regions along the east coast of the United States demonstrated significant negative correlations between species richness of terrestrial small mammals (orders Rodentia, In- sectivora, and Lagomorpha), a key group of hosts for ticks, and per capita numbers of reported Lyme disease cases, which supports our " dilution effect " hypothesis. We contrasted these findings to what might be expected when vectors acquire disease agents efficiently from many hosts, in which case infection prevalence of ticks may increase with increasing diversity hosts. A positive correlation between per capita Lyme disease cases and species richness of ground-dwelling birds supported this hypothesis, which we call the " rescue effect ." The reservoir competence of hosts within vertebrate communities and the degree of specialization by ticks on par- ticular hosts will strongly influence the relationship between species diversity and the risk of exposure to the many vector-borne diseases that plague humans.

PRIMUS: Constraints on Star Formation Quenching and Galaxy Merging, and the Evolution of the Stellar Mass Function from z = 0-1

Abstract: We measure the evolution of the stellar mass function (SMF) from z = 0−1 using multi-wavelength imaging and spectroscopic redshifts from the PRism MUlti-object Survey (PRIMUS) and the Sloan Digital Sky Survey (SDSS). From PRIMUS we construct an i < 23 flux-limited sample of ∼ 40,000 galaxies at z = 0.2 − 1.0 over five fields totaling ≈ 5.5 deg 2 , and from the SDSS we select ∼ 170,000 galaxies atz = 0.01−0.2 that we analyze consistently with respect to PRIMUS to minimize systematic errors in our evolutionary measurements. We find that the SMF of all galaxies evolves relatively little since z = 1, although we do find evidence for mass assembly downsizing; we measure a ≈ 30% increase in the number density of ∼ 10 10 M⊙ galaxies sincez ≈ 0.6, and a . 10% change in the number density of all & 10 11 M⊙ galaxies since z ≈ 1. Dividing the sample into star-forming and quiescent using an evolving cut in specific star-formation rate, we find that the number density of ∼ 10 10 M⊙ star-forming galaxies stays relatively constant since z ≈ 0.6, whereas the space-density of & 10 11 M⊙ star-forming galaxies decreases by ≈ 50% between z ≈ 1 and z ≈ 0. Meanwhile, the number density of ∼ 10 10 M⊙ quiescent galaxies increases steeply towards low redshift, by a factor of ∼ 2 − 3 since z ≈ 0.6, while the number of massive quiescent galaxies remains approximately constant since z ≈ 1. These results suggest that the rate at which star-forming galaxies are quenched increases with decreasing stellar mass, but that the bulk of the stellar mass buildup within the quiescent population occurs around ∼ 10 10.8 M⊙. In addition, we conclude that mergers do not appear to be a dominant channel for the stellar mass buildup of galaxies at z < 1, even among massive (& 10 11 M⊙) quiescent galaxies. Subject headings: Surveys – galaxies: evolution – galaxies: high-redshift – cosmology: large-scale structure of universe

Explaining leptokurtic movement distributions: intrapopulation variation in boldness and exploration.

Abstract: Leptokurtic distributions of movement distances observed in field‐release studies, in which some individuals move long distances while most remain at or near their release point, are a common feature of mobile animals. However, because leptokurtosis is predicted to be transient in homogeneous populations, persistent leptokurtosis suggests a population heterogeneity. We found evidence for a heterogeneity that may generate persistent leptokurtosis. We tested individuals of the Trinidad killifish Rivulus hartii for boldness in a tank test and released them back into their native stream. Boldness in the tank test predicted distance moved in the field releases, even after effects of size and sex were removed. Further, data from a 19‐mo mark‐recapture study showed that individual growth correlated positively with movement in a predator‐threatened river zone where the Rivulus population is spatially fragmented and dispersal is likely to be a hazardous activity. In contrast, no such correlation existed ...