1,214 research outputs found
Montana Fish, Wildlife and Parks ā A Wildlife Habitat Conservation Heritage
The course of wildlife habitat conservation in Montana was set in 1940, with the initial purchase of 1,000 acres, the āJudith River Game Rangeā.Ā This was the start of extensive investment in wildlife habitat conservation across the state.Ā Hunting license, PittmanRobertson Federal Aide, USDA Forest Legacy, and funds from many partners have helped to conserve and manage nearly 890,000 acres of high priority wildlife habitats across Montana.Ā I used historical records, program database queries, interviews, and popular articles from the Montana Outdoors publication to summarize conservation highlights from over the past 80 years.Ā Two programs have been instrumental in accomplishing perpetual conservation in recent history. Since 1987, Habitat Montana has invested over 66 million in partner funds.Ā Since 2001, the Forest Legacy Program has invested nearly 60 million of partner funding, specifically for forest land conservation.Ā In total, Montana Fish, Wildlife and Parks (FWP) and partners haveĀ invested 42 million of donated value by landowners.Ā FWP currently owns 385,000 acres, managed as wildlife management areas.Ā Wildlife habitat conservation easements total 448,000 acres, making FWP the 10th largest holder of conservation easements in the nation. Conserved habitats span coniferous forest, intermountain grasslands, riparian bottomlands, wetlands, prairie, and shrub grasslands, benefitting many species.Ā These lands substantially overlap with mapped priority habitats, involving hunted game and species of concern. Broad public support is essential to program survival.Ā Such support appears to hinge on various project outcomes, including conservation benefits, compatible recreation, economic benefits, managing land as a good neighbor, and tapping local producers to assist with management
A Comment on Priors for Bayesian Occupancy Models
Understanding patterns of species occurrence and the processes underlying these patterns is fundamental to the study of ecology. One of the more commonly used approaches to investigate species occurrence patterns is occupancy modeling, which can account for imperfect detection of a species during surveys. In recent years, there has been a proliferation of Bayesian modeling in ecology, which includes fitting Bayesian occupancy models. The Bayesian framework is appealing to ecologists for many reasons, including the ability to incorporate prior information through the specification of prior distributions on parameters. While ecologists almost exclusively intend to choose priors so that they are āuninformativeā or āvagueā, such priors can easily be unintentionally highly informative. Here we report on how the specification of a āvagueā normally distributed (i.e., Gaussian) prior on coefficients in Bayesian occupancy models can unintentionally influence parameter estimation. Using both simulated data and empirical examples, we illustrate how this issue likely compromises inference about species-habitat relationships. While the extent to which these informative priors influence inference depends on the data set, researchers fitting Bayesian occupancy models should conduct sensitivity analyses to ensure intended inference, or employ less commonly used priors that are less informative (e.g., logistic or t prior distributions). We provide suggestions for addressing this issue in occupancy studies, and an online tool for exploring this issue under different contexts
Clean and As-covered zinc-blende GaN (001) surfaces: Novel surface structures and surfactant behavior
We have investigated clean and As-covered zinc-blende GaN (001) surfaces,
employing first-principles total-energy calculations. For clean GaN surfaces
our results reveal a novel surface structure very different from the
well-established dimer structures commonly observed on polar III-V (001)
surfaces: The energetically most stable surface is achieved by a Peierls
distortion of the truncated (1x1) surface rather than through addition or
removal of atoms. This surface exhibits a (1x4) reconstruction consisting of
linear Ga tetramers. Furthermore, we find that a submonolayer of arsenic
significantly lowers the surface energy indicating that As may be a good
surfactant. Analyzing surface energies and band structures we identify the
mechanisms which govern these unusual structures and discuss how they might
affect growth properties.Comment: 4 pages, 3 figures, to be published in Appears in Phys. Rev. Lett.
(in print). Other related publications can be found at
http://www.rz-berlin.mpg.de/th/paper.htm
H2A.Z facilitates access of active and repressive complexes to chromatin in embryonic stem cell self-renewal and differentiation.
SummaryChromatin modifications have been implicated in the self-renewal and differentiation of embryonic stem cells (ESCs). However, the function of histone variant H2A.Z in ESCs remains unclear. We show that H2A.Z is highly enriched at promoters and enhancers and is required for both efficient self-renewal and differentiation of murine ESCs. H2A.Z deposition leads to an abnormal nucleosome structure, decreased nucleosome occupancy, and increased chromatin accessibility. In self-renewing ESCs, knockdown of H2A.Z compromises OCT4 binding to its target genes and leads to decreased binding of MLL complexes to active genes and of PRC2 complex to repressed genes. During differentiation of ESCs, inhibition of H2A.Z also compromises RA-induced RARĪ± binding, activation of differentiation markers, and the repression of pluripotency genes. We propose that H2A.Z mediates such contrasting activities by acting asĀ a general facilitator that generates access for a variety of complexes, both activating and repressive
ZnSe Heteroepitaxial Growth on Si (100) and GaAs (100)
The early stages of ZnSe heteroepitaxy on Si(100), Si(100):As and GaAs(100) are compared and contrasted, based on results of scanning tunneling microscopy and photoemission spectroscopy. High Se reactivity with the substrate constituents leads to bulk phase formation which is detrimental to heteroepitaxy. As-termination of Si(100) not only passivates the surface, but also provides an ideal buffer for ZnSe overgrowth. Lacking a similar buffer layer, stoichiometric control of the GaAs(100) surface is investigated to find a means for controlled heteroepitaxy
Why is the bandwidth of sodium observed to be narrower in photoemission experiments?
The experimentally predicted narrowing in the bandwidth of sodium is
interpreted in terms of the non-local self-energy effect on quasi-particle
energies of the electron liquid. The calculated self-energy correction is a
monotonically increasing function of the wavenumber variable. The usual
analysis of photo-emission experiments assumes the final state energies on the
nearly-free-electron-like model and hence it incorrectly ascribes the non-local
self-energy correction to the final state energies to the occupied state
energies, thus leading to a seeming narrowing in the bandwidth.Comment: 9 page
Thirty Years Of Wetland Conservation In Montana
In 1985 the Montana Legislature authorized the Department of Fish, Wildlife and Parks (FWP) to use funds from migratory bird hunting licenses āā¦for the protection, conservation, and development of wetlands in Montanaā, thereby creating the Migratory Bird Wetland Program (a.k.a. State Duck Stamp Program).Ā Wetlands and their associated uplands provide critical nesting, foraging, brood-rearing, and migration habitat for waterfowl and other wetland-associated wildlife.Ā Wetlands also provide critical ecosystem functions important for our communities and wildlife, including water purification, flood control, and groundwater recharge.Ā FWPās Migratory Bird Wetland Program is dedicated to conserving wetlands and associated uplands to benefit Montanaās wildlife, especially migratory birds, to enhance consumptive and non-consumptive recreational opportunities, and to maintain wetland systems for Montanaās citizens.Ā Since many of the opportunities were on private land, it was essential for FWP personnel to learn how best to work with farmers and ranchers to benefit their operations as well as wildlife and wetland values.Ā In addition to the partnership of private landowners, many other agencies and organizations have been partners in habitat projects.Ā The program has adapted to changing opportunities and conservation needs over time.Ā We will chronicle the past 30 years of program implementation, showcase successes, and discuss a philosophy for continued wetland conservation into the future
Behavioral and Demographic Responses of Mule Deer to Energy Development on Winter Range
Anthropogenic habitat modification is a major driver of global biodiversity loss. In North America, one of the primary sources of habitat modification over the last 2 decades has been exploration for and production of oil and natural gas (hydrocarbon development), which has led to demographic and behavioral impacts to numerous wildlife species. Developing effective measures to mitigate these impacts has become a critical task for wildlife managers and conservation practitioners. However, this task has been hindered by the difficulties involved in identifying and isolating factors driving population responses. Current research on responses of wildlife to development predominantly quantifies behavior, but it is not always clear how these responses scale to demography and population dynamics. Concomitant assessments of behavior and populationālevel processes are needed to gain the mechanistic understanding required to develop effective mitigation approaches. We simultaneously assessed the demographic and behavioral responses of a mule deer population to natural gas development on winter range in the Piceance Basin of Colorado, USA, from 2008 to 2015. Notably, this was the period when development declined from high levels of active drilling to only production phase activity (i.e., no drilling). We focused our data collection on 2 contiguous mule deer winter range study areas that experienced starkly different levels of hydrocarbon development within the Piceance Basin.
We assessed mule deer behavioral responses to a range of development features with varying levels of associated human activity by examining habitat selection patterns of nearly 400 individual adult female mule deer. Concurrently, we assessed the demographic and physiological effects of natural gas development by comparing annual adult female and overwinter fawn (6āmonthāold animals) survival, December fawn mass, adult female late and early winter body fat, age, pregnancy rates, fetal counts, and lactation rates in December between the 2 study areas. Strong differences in habitat selection between the 2 study areas were apparent. Deer in the lessādeveloped study area avoided development during the day and night, and selected habitat presumed to be used for foraging. Deer in the heavily developed study area selected habitat presumed to be used for thermal and security cover to a greater degree. Deer faced with higher densities of development avoided areas with more well pads during the day and responded neutrally or selected for these areas at night. Deer in both study areas showed a strong reduction in use of areas around well pads that were being drilled, which is the phase of energy development associated with the greatest amount of human presence, vehicle traffic, noise, and artificial light. Despite divergent habitat selection patterns, we found no effects of development on individual condition or reproduction and found no differences in any of the physiological or vital rate parameters measured at the population level. However, deer density and annual increases in density were higher in the lowādevelopment area. Thus, the recorded behavioral alterations did not appear to be associated with demographic or physiological costs measured at the individual level, possibly because populations are below winter range carrying capacity. Differences in population density between the 2 areas may be a result of a population decline prior to our study (when development was initiated) or areaāspecific differences in habitat quality, juvenile dispersal, or neonatal or juvenile survival; however, we lack the required data to contrast evidence for these mechanisms.
Given our results, it appears that deer can adjust to relatively high densities of well pads in the production phase (the period with markedly lower human activity on the landscape), provided there is sufficient vegetative and topographic cover afforded to them and populations are below carrying capacity. The strong reaction to wells in the drilling phase of development suggests mitigation efforts should focus on this activity and stage of development. Many of the wells in this area were directionally drilled from multipleāwell pads, leading to a reduced footprint of disturbance, but were still related to strong behavioral responses. Our results also indicate the likely value of mitigation efforts focusing on reducing human activity (i.e., vehicle traffic, light, and noise). In combination, these findings indicate that attention should be paid to the spatial configuration of the final development footprint to ensure adequate cover. In our study system, minimizing the road network through landscapeālevel development planning would be valuable (i.e., exploring a maximum road density criteria). Lastly, our study highlights the importance of concomitant assessments of behavior and demography to provide a comprehensive understanding of how wildlife respond to habitat modification
BioGlueĀ® is not associated with polypropylene suture breakage after aortic surgery
Objective: We have encountered broken or damaged polypropylene sutures (ProleneĀ®) at the anastomotic sites during aortic reoperations. Because a surgical sealant, bovine serum albumin-glutaraldehyde (BioGlueĀ®), was used in previous aortic surgery in some of these cases, we undertook this in vitro study to evaluate whether the use of BioGlueĀ® was associated with breakage of polypropylene sutures at the aortic anastomosis. Materials and methods: The broken polypropylene sutures, anastomotic sites and aortic tissue at the location of suture breakage were visually inspected and evaluated intraoperatively. Six human cadaveric aortic samples were incised circumferentially and anastomosed proximally to a valved conduit with running 4ā0 polypropylene sutures (ProleneĀ®). In the test group (n = 3), BioGlueĀ® was applied directly to the ProleneĀ® sutures at the anastomotic sites, while in the control group (n = 3) the anastomoses were not sealed with any surgical adhesive. The six samples were immersed in Dulbecco's phosphate buffered saline solution and mounted on a M-6 Six Position Heart Valve Durability Testing System and tested up to 120 million cycles for a 2-year period. During and upon completion of the testing, the integrity of ProleneĀ® sutures, the anastomosis and aortic tissues was regularly assessed by visual inspection. Results: Intraoperative findings included a stretched and thin aortic wall (some with thrombus), a small cleft between the aortic tissue and the Dacron vascular graft. An excessive amount of BioGlueĀ® was often found around the anastomosis, with cracking material, but no signs of mechanical damage were observed in these cases. Upon visual inspection during and after in vitro testing, there was no apparent damage to the polypropylene sutures on the interior or exterior of the aortic anastomoses in any of the samples. No difference was observed in the physical integrity of the polypropylene sutures at anastomotic lines, the anastomoses and aortic tissues between the test and control samples. Conclusions: The results of this study suggest that the use of BioGlueĀ® was not associated with breakage of the polypropylene sutures at the anastomotic sites after aortic dissection repair
Hydrophobic interactions: an overview
We present an overview of the recent progress that has been made in
understanding the origin of hydrophobic interactions. We discuss the different
character of the solvation behavior of apolar solutes at small and large length
scales. We emphasize that the crossover in the solvation behavior arises from a
collective effect, which means that implicit solvent models should be used with
care. We then discuss a recently developed explicit solvent model, in which the
solvent is not described at the atomic level, but rather at the level of a
density field. The model is based upon a lattice-gas model, which describes
density fluctuations in the solvent at large length scales, and a Gaussian
model, which describes density fluctuations at smaller length scales. By
integrating out the small length scale field, a Hamiltonian is obtained, which
is a function of the binary, large-length scale field only. This makes it
possible to simulate much larger systems than hitherto possible as demonstrated
by the application of the model to the collapse of an ideal hydrophobic
polymer. The results show that the collapse is dominated by the dynamics of the
solvent, in particular the formation of a vapor bubble of critical size.
Implications of these findings to the understanding of pressure denaturation of
proteins are discussed.Comment: 10 pages, 4 figure
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