12,373 research outputs found
Coastal Conservation Lands Update (2005)
The Complex Systems Research Center (CSRC) at the University of New Hampshire has developed, implemented, and coordinated the GRANIT GIS clearinghouse since its inception in the mid 1980’s. One of the primary data sets maintained by CSRC and served through the clearinghouse is the Conservation and Protected Lands Data Layer. This data set contains a digital record of parcels of land of two or more acres that are mostly undeveloped and are protected from future development. Smaller parcels that adjoin previously mapped parcels or represent unique features, such as a bog or state-owned boat ramp, may also be included in this data layer. Through the GRANIT Conservation Lands Data Layer Update project, data on current protected lands were collected, reviewed, and processed for 48 communities in seacoast NH, including the 42 towns within the NH Estuaries Project area. GRANIT staff contacted each community’s conservation commission, as well as all quasi-public entities and land trusts active in the region, to solicit updates and additions to the data set. Concurrently, staff from the NH Office of Energy and Planning contacted the state and federal agencies that manage property in the seacoast to request comparable information. Through this collaborative process, 166 new tracts covering over 6,000 acres were added to the database. In addition, information on 122 existing tracts was modified to incorporate the reported corrections
GRANIT Conservation Lands Data Layer Update
The Complex Systems Research Center (CSRC) at the University of New Hampshire has developed, implemented, and coordinated the GRANIT GIS clearinghouse since its inception in the mid 1980’s. One of the primary data sets maintained by CSRC and served through the clearinghouse is the GRANIT Conservation and Protected Lands Data Layer. This data set contains a digital record of parcels of land of two or more acres that are mostly undeveloped and are protected from future development. Smaller parcels that adjoin previously mapped parcels or represent unique features, such as a bog or state-owned boat ramp, may also be included in the data layer. Through the GRANIT Conservation Lands Data Layer Update project, current protected lands data were collected, reviewed, and processed for the 47-community area within the NH Estuaries Project study area. GRANIT staff contacted each community’s conservation commission to solicit updates. Concurrently, staff from the Society for the Protection of NH Forests contacted the active land trusts in the region. Through this collaborative process, 235 tracts covering 6,997 acres were added to the database. In addition to new tracts, information for existing tracts was modified to incorporate any reported corrections. The resulting, updated data set is available to municipal decision-makers, the land trust community, and the general public through the GRANIT web site (www.granit.sr.unh.edu) and the GRANIT Conservation Lands Viewer (www.granitmap.sr.unh.edu)
Self heating and nonlinear current-voltage characteristics in bilayer graphene
We demonstrate by experiments and numerical simulations that the
low-temperature current-voltage characteristics in diffusive bilayer graphene
(BLG) exhibit a strong superlinearity at finite bias voltages. The
superlinearity is weakly dependent on doping and on the length of the graphene
sample. This effect can be understood as a result of Joule heating. It is
stronger in BLG than in monolayer graphene (MLG), since the conductivity of BLG
is more sensitive to temperature due to the higher density of electronic states
at the Dirac point.Comment: 9 pages, 7 figures, REVTeX 4.
Effect of spin orbit scattering on the magnetic and superconducting properties of nearly ferromagnetic metals: application to granular Pt
We calculate the effect of scattering on the static, exchange enhanced, spin
susceptibility and show that in particular spin orbit scattering leads to a
reduction of the giant moments and spin glass freezing temperature due to
dilute magnetic impurities. The harmful spin fluctuation contribution to the
intra-grain pairing interaction is strongly reduced opening the way for BCS
superconductivity. We are thus able to explain the superconducting and magnetic
properties recently observed in granular Pt as due to scattering effects in
single small grains.Comment: 9 pages 3 figures, accepted for publication in Phys. Rev. Letter
Beyond Node Degree: Evaluating AS Topology Models
This is the accepted version of 'Beyond Node Degree: Evaluating AS Topology Models', archived originally at arXiv:0807.2023v1 [cs.NI] 13 July 2008.Many models have been proposed to generate Internet Autonomous System (AS) topologies, most of which make structural assumptions about the AS graph. In this paper we compare AS topology generation models with several observed AS topologies. In contrast to most previous works, we avoid making assumptions about which topological properties are important to characterize the AS topology. Our analysis shows that, although matching degree-based properties, the existing AS topology generation models fail to capture the complexity of the local interconnection structure between ASs. Furthermore, we use BGP data from multiple vantage points to show that additional measurement locations significantly affect local structure properties, such as clustering and node centrality. Degree-based properties, however, are not notably affected by additional measurements locations. These observations are particularly valid in the core. The shortcomings of AS topology generation models stems from an underestimation of the complexity of the connectivity in the core caused by inappropriate use of BGP data
Shot noise and conductivity at high bias in bilayer graphene: Signatures of electron-optical phonon coupling
We have studied electronic conductivity and shot noise of bilayer graphene
(BLG) sheets at high bias voltages and low bath temperature K. As a
function of bias, we find initially an increase of the differential
conductivity, which we attribute to self-heating. At higher bias, the
conductivity saturates and even decreases due to backscattering from optical
phonons. The electron-phonon interactions are also responsible for the decay of
the Fano factor at bias voltages V. The high bias electronic
temperature has been calculated from shot noise measurements, and it goes up to
K at V. Using the theoretical temperature dependence of BLG
conductivity, we extract an effective electron-optical phonon scattering time
. In a 230 nm long BLG sample of mobility
cmVs, we find that decreases with increasing
voltage and is close to the charged impurity scattering time fs
at V.Comment: 7 pages, 7 figures. Extended version of the high bias part of version
1. The low bias part is discussed in arXiv:1102.065
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Complete Genomes of Symbiotic Cyanobacteria Clarify the Evolution of Vanadium-Nitrogenase.
Plant endosymbiosis with nitrogen-fixing cyanobacteria has independently evolved in diverse plant lineages, offering a unique window to study the evolution and genetics of plant-microbe interaction. However, very few complete genomes exist for plant cyanobionts, and therefore little is known about their genomic and functional diversity. Here, we present four complete genomes of cyanobacteria isolated from bryophytes. Nanopore long-read sequencing allowed us to obtain circular contigs for all the main chromosomes and most of the plasmids. We found that despite having a low 16S rRNA sequence divergence, the four isolates exhibit considerable genome reorganizations and variation in gene content. Furthermore, three of the four isolates possess genes encoding vanadium (V)-nitrogenase (vnf), which is uncommon among diazotrophs and has not been previously reported in plant cyanobionts. In two cases, the vnf genes were found on plasmids, implying possible plasmid-mediated horizontal gene transfers. Comparative genomic analysis of vnf-containing cyanobacteria further identified a conserved gene cluster. Many genes in this cluster have not been functionally characterized and would be promising candidates for future studies to elucidate V-nitrogenase function and regulation
Performance of the 19XB 10-Stage Axial-Flow Compressor with Altered Blade Angles
Previous performance data of the 19XB axial-flow compressor indicated that the outlet guide vanes and possibly the inlet guide vanes were stalling. Calculations were made to determine if these adverse conditions could be eliminated and if the manufacturer's design specifications could be more nearly approached by altering the blade angles of the first few compression stages as well as the outlet guide vanes. With the blade angles altered, experimental data were taken at compressor speeds of 8500 to 17,000 rpm with inlet-air conditions of 7.4 inches of mercury absolute and 59 0 F. The temperature-rise efficiency increased with speed from 0.70 at 8500 rpm to 0.74 at 13,600 rpm and dropped gradually to 0.70 at 17,000 rpm. At the design speed of 17,000 rpm, the pressure ratio at the peak efficiency point was 3.63. The maximum pressure ratio at design speed was 4.15 at an equivalent weight flow of 29.8 pounds per second. The altered compressor operated very .near the design specifications of pressure ratio and equivalent weight flow. At the high speeds, the peak adiabatic temperature-rise efficiency was increased 0.02 to 0,06 by altering the blade angles. The peak pressure ratio was increased 0.29 at design speed (17,000 rpm) and 0.05 and 0.13 at 11,900 and 13,600 rpm, respectively. The equivalent weight flow through the altered compressor was reduced 2 pounds per second at 15,300 and 17,000 rpm, as was expected from the design calculations. As extreme caution was taken not to surge the compressor violently, the point of minimum air flow may not have been reached in the present investigation and in a previous investigation. A true comparison of the pressure ratios obtained at the high speeds therefore cannot be made
Fluorescent visualization of a spreading surfactant
The spreading of surfactants on thin films is an industrially and medically
important phenomenon, but the dynamics are highly nonlinear and visualization
of the surfactant dynamics has been a long-standing experimental challenge. We
perform the first quantitative, spatiotemporally-resolved measurements of the
spreading of an insoluble surfactant on a thin fluid layer. During the
spreading process, we directly observe both the radial height profile of the
spreading droplet and the spatial distribution of the fluorescently-tagged
surfactant. We find that the leading edge of spreading circular layer of
surfactant forms a Marangoni ridge in the underlying fluid, with a trough
trailing the ridge as expected. However, several novel features are observed
using the fluorescence technique, including a peak in the surfactant
concentration which trails the leading edge, and a flat, monolayer-scale
spreading film which differs from concentration profiles predicted by current
models. Both the Marangoni ridge and surfactant leading edge can be described
to spread as . We find spreading exponents, and for the ridge peak and
surfactant leading edge, respectively, which are in good agreement with
theoretical predictions of . In addition, we observe that the
surfactant leading edge initially leads the peak of the Marangoni ridge, with
the peak later catching up to the leading edge
Effects of maternal subnutrition during early pregnancy on cow hematological profiles and offspring physiology and vitality in two beef breeds
This experiment evaluated the effects of subnutrition during early gestation on hematology in cows (Bos Taurus) and on hematological, metabolic, endocrine, and vitality parameters in their calves. Parda de Montaña and Pirenaica dams were inseminated and assigned to either a control (CONTROL, 100% requirements) or a nutrient‐restricted group (SUBNUT, 65%) during the first third of gestation. Dam blood samples were collected on days 20 and 253 of gestation, and calf samples were obtained during the first days of life. Pirenaica dams presented higher red series parameters than Parda de Montaña dams, both in the first and the last months of gestation. During early pregnancy, granulocyte numbers and mean corpuscular hemoglobin were lower in Pirenaica‐SUBNUT than in Pirenaica‐CONTROL cows. Calves from the SUBNUT cows did not show a physiological reduction in red series values in early life, suggesting later maturation of the hematopoietic system. Poor maternal nutrition affected calf endocrine parameters. Newborns from dystocic parturitions showed lower NEFA concentrations and weaker vitality responses. In conclusion, maternal nutrition had short‐term effects on cow hematology, Pirenaica cows showing a higher susceptibility to undernutrition; and a long‐term effect on their offspring endocrinology, SUBNUT newborns showing lower levels of IGF‐1 and higher levels of cortisol.This work was supported by the Spanish Ministry of Economy and Business and the European Union Regional Development Funds (INIA RTA 2013‐00059‐C02 and INIA RZP 2015‐001) and the Government of Aragon under the Grant Research Group Funds (A14_17R). A. Noya received a PhD grant from INIA‐Government of Aragon
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