1,581 research outputs found
Using Topography to Meet Wildlife and Fuels Treatment Objectives in Fire-Suppressed Landscapes
Past forest management practices, fire suppression, and climate change are increasing the need to actively manage California Sierra Nevada forests for multiple environmental amenities. Here we present a relatively low-cost, repeatable method for spatially parsing the landscape to help the U.S. Forest Service manage for different forest and fuel conditions to meet multiple goals relating to sensitive species, fuels reduction, forest products, water, carbon storage, and ecosystem restoration. Using the Kings River area of the Sierra Nevada as a case study, we create areas of topographically-based units, Landscape Management Units (LMUs) using a three by three matrix (canyon, mid-slope, ridge-top and northerly, southerly, and neutral aspects). We describe their size, elevation, slope, aspect, and their difference in inherent wetness and solar radiation. We assess the predictive value and field applicability of LMUs by using existing data on stand conditions and two sensitive wildlife species. Stand conditions varied significantly between LMUs, with canyons consistently having the greatest stem and snag densities. Pacific fisher (Martes pennanti) activity points (from radio telemetry) and California spotted owl (Strix occidentalis occidentalis) nests, roosts, and sightings were both significantly different from uniform, with a disproportionate number of observations in canyons, and fewer than expected on ridge-tops. Given the distinct characteristics of the LMUs, these units provide a relatively simple but ecologically meaningful template for managers to spatially allocate forest treatments, thereby meeting multiple National Forest objectives. These LMUs provide a framework that can potentially be applied to other fire-dependent western forests with steep topographic relief
Topological rigidity and H_1-negative involutions on tori
We prove there is only one involution (up to conjugacy) on the n-torus which
acts as on the first homology group when is of the form
, is of the form , or is less than . In all other cases we prove
there are infinitely many such involutions up to conjugacy, but each of them
has exactly fixed points and is conjugate to a smooth involution. The key
technical point is that we completely compute the equivariant structure set for
the corresponding crystallographic group action on in terms of
the Cappell -groups arising from its infinite dihedral
subgroups. We give a complete analysis of equivariant topological rigidity for
this family of groups.Comment: 50 pages, to appear in Geometry & Topolog
Successful Application of Large Microneedle Patches by Human Volunteers
We describe, for the first time, the design, production and evaluation of large microneedle patches. Such systems, based on 16 individual microneedle arrays (needle height 600 μm), were prepared from aqueous blends of 15% w/w Gantrez(®) S97 and 7.5% w/w poly(ethyleneglycol) 10,000 Da. Ester-based crosslinking was confirmed by FTIR and mechanical strength was good. Insertion depths in a validated skin model were approximately 500 μm. Ten human volunteers successfully self-inserted the microneedles of these larger patches in their skin, following appropriate instruction, as confirmed by transepidermal water loss measurements. The mean insertion depth ranged between 300 and 450 μm over the area of the large patches. That this was not significantly different to a single unit MN patch self-applied by the same volunteers is encouraging. Microneedle patch sizes much larger than the 1–2 cm(2) will be required if this technology is to be successfully translated to clinic for delivery of drug substances. The work described here suggests that use of such larger patches by patients can be successful, potentially opening up the possibility for a significant expansion of the size of the market for transdermal drug delivery
Prospective, Randomized, Controlled Trial of Tissue Adhesive (2-Octylcyanoacrylate) vs Standard Wound Closure Techniques for Laceration Repair
Objective: To compare a new tissue adhesive, 2-octylcyanoacrylate, with standard wound closure techniques for the repair of traumatic lacerations. Methods: A prospective, randomized, controlled clinical trial enrolled consecutive patients >1 year of age with non-bite, non-crush-induced lacerations who presented 3 months) was assessed by physicians using a previously validated categorical cosmetic scale and by patients using a 100-mm visual analog scale. Results : There were 63 patients randomized to the octylcyanoacrylate group and 61 patients treated with standard wound closure techniques. The 2 treatment groups were similar with respect to age, gender, race, medical history, and wound characteristics. At the 5-to-10-day follow-up, only 1 wound was infected and only 2 wounds required reclosure due to dehiscence. These 3 patients received treatment with octylcyanoacrylate. At long-term follow-up, the cosmetic appearances were similar according to the patients (octylcyanoacrylate, 83.8 ± 19.4 mm vs standard techniques, 82.5 ± 17.6 mm; p = 0.72) and the physicians (optimal cosmetic appearance, 77% vs 80%; p = 0.67). Conclusions: Wounds treated with octylcyanoacrylate and standard wound closure techniques have similar cosmetic appearances 3 months later.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75580/1/j.1553-2712.1998.tb02590.x.pd
Aquatic biosurvey of the Lovell River on UNH land
We assessed the physical, chemical and biological conditions at two sites along the Lovell River on University of New Hampshire (UNH) -owned conservation land. The discharge was 4.4 m3 s-1 at Site 1 and 5.7 m3 s -1 downstream at Site 2. Canopy coverage ranged from 8-25%. Canopy was dominated by Eastern Hemlock (79-84%). Much of the stream was strewn with large boulders and the substrate consisted of rocks of highly variable sizes ( 3-549 cm dia.). Specific conductivity (22.1-23.3 µS), pH (6.4) and temperature (7.9-8.3 °C) varied little between sites. Macro-invertebrate bio-indices indicated either excellent water quality with no apparent organic pollution (3.0/10) or good water quality with possible slight organic pollution (4.4/10)
Is there Evidence for Flat Cores in the Halos of Dwarf Galaxies?: The Case of NGC 3109 and NGC 6822
Two well studied dwarf galaxies -- NGC 3109 and NGC 6822 -- present some of
the strongest observational support for a flat core at the center of galactic
dark matter (DM) halos. We use detailed cosmologically motivated numerical
models to investigate the systematics and the accuracy of recovering parameters
of the galaxies. Some of our models match the observed structure of the two
galaxies remarkably well. Our analysis shows that the rotation curves of these
two galaxies are instead quite compatible with their DM halos having steep
cuspy density profiles. The rotation curves in our models are measured using
standard observational techniques. The models reproduce the rotation curves of
both galaxies, the disk surface brightness profiles as well as the profile of
isophotal ellipticity and position angle. The models are centrally dominated by
baryons; however, the dark matter component is globally dominant. The simulated
disk mass is marginally consistent with a stellar mass-to-light ratio in
agreement with the observed colors. We show that non-circular motions combined
with gas pressure support and projection effects results in a large
underestimation of the circular velocity in the central kpc region,
creating the illusion of a constant density core. Although the systematic
effects mentioned above are stronger in barred systems, they are also present
in axisymetric disks. Our results strongly suggest that there is no
contradiction between the observed rotation curves in dwarf galaxies and the
cuspy central dark matter density profiles predicted by Cold Dark Matter
models.Comment: Accepted for publication in the ApJ. New discussion, figures and one
appendix. High resolution version
at:http://www.astro.washington.edu/octavio/N3109_paper.ps.g
Sustainable Sourcing of Global Agricultural Raw Materials: Assessing Gaps in Key Impact and Vulnerability Issues and Indicators.
Understanding how to source agricultural raw materials sustainably is challenging in today's globalized food system given the variety of issues to be considered and the multitude of suggested indicators for representing these issues. Furthermore, stakeholders in the global food system both impact these issues and are themselves vulnerable to these issues, an important duality that is often implied but not explicitly described. The attention given to these issues and conceptual frameworks varies greatly--depending largely on the stakeholder perspective--as does the set of indicators developed to measure them. To better structure these complex relationships and assess any gaps, we collate a comprehensive list of sustainability issues and a database of sustainability indicators to represent them. To assure a breadth of inclusion, the issues are pulled from the following three perspectives: major global sustainability assessments, sustainability communications from global food companies, and conceptual frameworks of sustainable livelihoods from academic publications. These terms are integrated across perspectives using a common vocabulary, classified by their relevance to impacts and vulnerabilities, and categorized into groups by economic, environmental, physical, human, social, and political characteristics. These issues are then associated with over 2,000 sustainability indicators gathered from existing sources. A gap analysis is then performed to determine if particular issues and issue groups are over or underrepresented. This process results in 44 "integrated" issues--24 impact issues and 36 vulnerability issues--that are composed of 318 "component" issues. The gap analysis shows that although every integrated issue is mentioned at least 40% of the time across perspectives, no issue is mentioned more than 70% of the time. A few issues infrequently mentioned across perspectives also have relatively few indicators available to fully represent them. Issues in the impact framework generally have fewer gaps than those in the vulnerability framework
The Structural Evolution of Substructure
We investigate the evolution of substructure in cold dark matter halos using
N-body simulations of tidal stripping of substructure halos (subhalos) within a
static host potential. We find that halos modeled following the Navarro, Frenk
& White (NFW) mass profile lose mass continuously due to tides from the massive
host, leading to the total disruption of satellite halos with small tidal
radii. The structure of stripped NFW halos depends mainly on the fraction of
mass lost, and can be expressed in terms of a simple correction to the original
NFW profile. We apply these results to substructure in the Milky Way, and
conclude that the dark matter halos surrounding its dwarf spheroidal (dSph)
satellites have circular velocity curves that peak well beyond the luminous
radius at velocities significantly higher than expected from the stellar
velocity dispersion. Our modeling suggests that the true tidal radii of dSphs
lie well beyond the putative tidal cutoff observed in the surface brightness
profile, suggesting that the latter are not really tidal in origin but rather
features in the light profile of limited dynamical relevance. For Draco, in
particular, our modeling implies that its tidal radius is much larger than
derived by Irwin & Hatzidimitriou (1995), lending support to the interpretation
of recent Sloan survey data by Odenkirchen et al. (2001). Similarly, our model
suggests that Carina's halo has a peak circular velocity of ~55 km/s, which may
help explain how this small galaxy has managed to retain enough gas to undergo
several bursts of star formation. Our results imply a close correspondence
between the most massive subhalos expected in a CDM universe and the known
satellites of the Milky Way, and suggest that only subhalos with peak circular
velocities below 35 km/s lack readily detectable luminous counterparts.Comment: 28 pages, 14 figures; accepted for publication in the Astrophysical
Journa
The Metamorphosis of Tidally Stirred Dwarf Galaxies
We present results from high-resolution N-Body/SPH simulations of
rotationally supported dwarf irregular galaxies moving on bound orbits in the
massive dark matter halo of the Milky Way.The dwarf models span a range in disk
surface density and the masses and sizes of their dark halos are consistent
with the predictions of cold dark matter cosmogonies. We show that the strong
tidal field of the Milky Way determines severe mass loss in their halos and
disks and induces bar and bending instabilities that transform low surface
brightness dwarfs (LSBs) into dwarf spheroidals (dSphs) and high surface
brightness dwarfs (HSBs) into dwarf ellipticals (dEs) in less than 10 Gyr. The
final central velocity dispersions of the remnants are in the range 8-30 km/s
and their final falls to values , matching well the
kinematics of early-type dwarfs. The transformation requires the orbital time
of the dwarf to be \simlt 3-4 Gyr, which implies a halo as massive and
extended as predicted by hierarchical models of galaxy formation to explain the
origin of even the farthest dSph satellites of the Milky Way, Leo I and Leo II.
Only dwarfs with central dark matter densities as high as those of Draco and
Ursa Minor can survive for 10 Gyr in the proximity of the Milky Way: this is
naturally achieved within hierarchical models, where the densest objects should
have small orbital times due to their early formation epochs. Part of the gas
is stripped and part is funneled to the center due to the bar, generating one
strong burst of star formation in HSBs and smaller, multiple bursts in LSBs.
Extended low-surface brightness stellar and gaseous streams originate from LSBs
and, when projected along the line of sight, can lead to overestimate the
mass-to-light ratio of the bound remnant by a factor \simlt 2,Comment: 29 pages, 34 figures, submitted to ApJ. Figures 5,11 and 32 are given
as separate GIF files. Other figures and the movies of the simulations can be
found at http://pcblu.mib.infn.it/~lucio/LG/LG.htm
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