836 research outputs found
Disturbance distance: quantifying forests' vulnerability to disturbance under current and future conditions
Disturbances, both natural and anthropogenic, are critical determinants of forest structure, function,
and distribution. The vulnerability of forests to potential changes in disturbance rates remains largely
unknown. Here, we developed a framework for quantifying and mapping the vulnerability of forests
to changes in disturbance rates. By comparing recent estimates of observed forest disturbance rates
over a sample of contiguous US forests to modeled rates of disturbance resulting in forest loss, a novel
index of vulnerability, Disturbance Distance, was produced. Sample results indicate that 20% of
current US forestland could be lost if disturbance rates were to double, with southwestern forests
showing highest vulnerability. Under a future climate scenario, the majority of US forests showed
capabilities of withstanding higher rates of disturbance then under the current climate scenario,
which may buffer some impacts of intensified forest disturbanceinfo:eu-repo/semantics/publishedVersio
HEPCloud, a New Paradigm for HEP Facilities: CMS Amazon Web Services Investigation
Historically, high energy physics computing has been performed on large
purpose-built computing systems. These began as single-site compute facilities,
but have evolved into the distributed computing grids used today. Recently,
there has been an exponential increase in the capacity and capability of
commercial clouds. Cloud resources are highly virtualized and intended to be
able to be flexibly deployed for a variety of computing tasks. There is a
growing nterest among the cloud providers to demonstrate the capability to
perform large-scale scientific computing. In this paper, we discuss results
from the CMS experiment using the Fermilab HEPCloud facility, which utilized
both local Fermilab resources and virtual machines in the Amazon Web Services
Elastic Compute Cloud. We discuss the planning, technical challenges, and
lessons learned involved in performing physics workflows on a large-scale set
of virtualized resources. In addition, we will discuss the economics and
operational efficiencies when executing workflows both in the cloud and on
dedicated resources.Comment: 15 pages, 9 figure
Latitudinal variation in ecological opportunity and intraspecific competition indicates differences in niche variability and diet specialization of Arctic marine predators
Individual specialization (IS), where individuals within populations irrespective of age, sex, and body size are either specialized or generalized in terms of resource use, has implications on ecological niches and food web structure. Niche size and degree of IS of nearâtop trophicâlevel marine predators have been little studied in polar regions or with latitude. We quantified the largeâscale latitudinal variation of populationâ and individualâlevel niche size and IS in ringed seals (Pusa hispida) and beluga whales (Delphinapterus leucas) using stable carbon and nitrogen isotope analysis on 379 paired ringed seal liver and muscle samples and 124 paired beluga skin and muscle samples from eight locations ranging from the low to high Arctic. We characterized both withinâ and betweenâindividual variation in predator niche size at each location as well as accounting for spatial differences in the isotopic ranges of potential prey. Total isotopic niche width (TINW) for populations of ringed seals and beluga decreased with increasing latitude. Higher TINW values were associated with greater ecological opportunity (i.e., prey diversity) in the prey fish community which mainly consists of Capelin (Mallotus villosus) and Sand lance (Ammodytes sp.) at lower latitudes and Arctic cod (Boreogadus saida) at high latitudes. In beluga, their dietary consistency between tissues also known as the withinâindividual component (WIC) increased in a near 1:1 ratio with TINW (slope = 0.84), suggesting dietary generalization, whereas the slope (0.18) of WIC relative to TINW in ringed seals indicated a high degree of individual specialization in ringed seal populations with higher TINWs. Our findings highlight the differences in TINW and level of IS for ringed seals and beluga relative to latitude as a likely response to largeâscale spatial variation in ecological opportunity, suggesting speciesâspecific variation in dietary plasticity to spatial differences in prey resources and environmental conditions in a rapidly changing ecosystem
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