8,179 research outputs found
Classification of Coastal Communities Reporting Commercial Fish Landings in the U.S. Northeast Region: Developing and Testing a Methodology
The National Marine Fisheries Service is required by law to conduct social impact assessments of communities impacted by fishery management plans. To facilitate this process, we developed a technique for grouping communities based on common sociocultural attributes. Multivariate data reduction techniques (e.g. principal component analyses, cluster analyses) were used to classify Northeast U.S. fishing communities based on census and fisheries data. The comparisons indicate that the clusters represent real groupings that can be verified with the profiles. We then selected communities representative of different values on these multivariate dimensions for in-depth analysis. The derived clusters are then compared based on more detailed data from fishing community profiles. Ground-truthing (e.g. visiting the communities and collecting primary information) a sample of communities from three clusters (two overlapping geographically) indicates that the more remote techniques are sufficient for typing the communities for further in-depth analyses. The in-depth analyses provide additional important information which we contend is representative of all communities within the cluster
Alien Registration- Smith, Sarah L. (Houlton, Aroostook County)
https://digitalmaine.com/alien_docs/34874/thumbnail.jp
Impurity transport in a mixed-collisionality stellarator plasma
A potential threat to the performance of magnetically confined fusion plasmas
is the problem of impurity accumulation, which causes the concentration of
highly charged impurity ions to rise uncontrollably in the center of the plasma
and spoil the energy confinement by excessive radiation. It has long been
thought that the collisional transport of impurities in stellarators always
leads to such accumulation (if the electric field points inwards, which is
usually the case), whereas tokamaks, being axisymmetric, can benefit from
"temperature screening", i.e., an outward flux of impurities driven by the
temperature gradient. Here it is shown, using analytical techniques supported
by results from a new numerical code, that such screening can arise in
stellarator plasmas too, and indeed does so in one of the most relevant
operating regimes, where the impurities are highly collisional whilst the bulk
plasma is in any of the low-collisionality regimes.Comment: 11 pages, 3 figure
Impurity transport and bulk ion flow in a mixed collisionality stellarator plasma
The accumulation of impurities in the core of magnetically confined plasmas,
resulting from standard collisional transport mechanisms, is a known threat to
their performance as fusion energy sources. Whilst the axisymmetric tokamak
systems have been shown to benefit from the effect of temperature screening,
that is an outward flux of impurities driven by the temperature gradient,
impurity accumulation in stellarators was thought to be inevitable, driven
robustly by the inward pointing electric field characteristic of hot fusion
plasmas. We have shown in Helander et. al. (2017b) that such screening can in
principle also appear in stellarators, in the experimentally relevant mixed
collisionality regime, where a highly collisional impurity species is present
in a low collisionality bulk plasma. Details of the analytic calculation are
presented here, along with the effect of the impurity on the bulk ion flow,
which will ultimately affect the bulk contribution to the bootstrap current
Line tensions, correlation lengths, and critical exponents in lipid membranes near critical points
Membranes containing a wide variety of ternary mixtures of high chain-melting
temperature lipids, low chain-melting temperature lipids, and cholesterol
undergo lateral phase separartion into coexisting liquid phases at a
miscibility transition. When membranes are prepared from a ternary lipid
mixture at a critical composition, they pass through a miscibility critical
point at the transition temperature. Since the critical temperature is
typically on the order of room temperature, membranes provide an unusual
opportunity in which to perform a quantitative study of biophysical systems
that exhibit critical phenomena in the two-dimensional Ising universality
class. As a critical point is approached from either high or low temperature,
the scale of fluctuations in lipid composition, set by the correlation length,
diverges. In addition, as a critical point is approached from low temperature,
the line tension between coexisting phases decreases to zero. Here we
quantitatively evaluate the temperature dependence of line tension between
liquid domains and of fluctuation correlation lengths in lipid membranes in
order to extract a critical exponent, nu. We obtain nu=1.2 plus or minus 0.2,
consistent with the Ising model prediction nu=1. We also evaluate the
probability distributions of pixel intensities in fluoresence images of
membranes. From the temperature dependence of these distributions above the
critical temperature, we extract an independent critical exponent beta=0.124
plus or minus 0.03 which is consistent with the Ising prediction of beta=1/8.Comment: 22 pages, 7 figure
Double-Peaked Narrow-Line Active Galactic Nuclei. II. The Case Of Equal Peaks
Active galactic nuclei (AGNs) with double-peaked narrow lines (DPAGNs) may be caused by kiloparsec-scale binary AGNs, bipolar outflows, or rotating gaseous disks. We examine the class of DPAGNs in which the two narrow-line components have closely similar intensity as being especially likely to involve disks or jets. Two spectroscopic indicators support this likelihood. For DPAGNs from Smith et al., the "equal-peaked" objects (EPAGNs) have [Ne V]/[O III] ratios lower than for a control sample of non-double-peaked AGNs. This is unexpected for a pair of normal AGNs in a galactic merger, but may be consistent with [O III] emission from a rotating ring with relatively little gas at small radii. Also, [O III]/H beta ratios of the redshifted and blueshifted systems in the EPAGN are more similar to each other than in a control sample, suggestive of a single ionizing source and inconsistent with the binary interpretation.University Cooperative Society of the University of Texas at AustinJane and Roland Blumberg Cenntenial Professorship in AstronomyAlfred P. Sloan FoundationNational Aeronautics and Space AdministrationNational Science FoundationU.S. Department of EnergyJapanese MonbukagakushoMax Planck SocietyUniversity of ChicagoInstitute for Advanced StudyJapan Participation GroupJohns Hopkins UniversityKorean Scientist GroupLos Alamos National LaboratoryMax-Planck-Institute for Astronomy (MPIA)Max-Planck-Institute for Astrophysics (MPA)New Mexico State UniversityUniversity of PittsburghUniversity of PortsmouthPrinceton UniversityUnited States Naval ObservatoryUniversity of WashingtonFermilabAstronom
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The Jet-Driven Outflow In The Radio Galaxy SDSS J1517+3353: Implications For Double-Peaked Narrow-Line Active Galactic Nucleus
We report on the study of an intriguing active galaxy that was selected as a potential multiple supermassive black hole merger in the early-type host SDSS J151709.20+335324.7 (z = 0.135) from a complete search for double-peaked [O III] lines from the SDSS spectroscopic quasi-stellar object (QSO) database. Ground-based SDSS imaging reveals two blue structures on either side of the photometric center of the host galaxy, separated from each other by about 5.7 kpc. From a combination of SDSS fiber and Keck/HIRES long-slit spectroscopy, it is demonstrated that, in addition to these two features, a third distinct structure surrounds the nucleus of the host galaxy. All three structures exhibit highly ionized line emission with line ratios characteristic of Seyfert II active galactic nuclei. The analysis of spatially resolved emission-line profiles from the HIRES spectrum reveal three distinct kinematic subcomponents, one at rest and the other two moving at -350 km s(-1) and 500 km s(-1) with respect to the systemic velocity of the host galaxy. A comparison of imaging and spectral data confirm a strong association between the kinematic components and the spatial knots, which implies a highly disturbed and complex active region in this object. A comparative analysis of the broadband positions, colors, kinematics, and spectral properties of the knots in this system lead to two plausible explanations: (1) a multiple active galactic nucleus (AGN) produced due to a massive dry merger, or (2) a very powerful radio jet-driven outflow. Subsequent VLA radio imaging reveals a clear jet aligned with the emission-line gas, confirming the latter explanation. We use the broadband radio measurements to examine the impact of the jet on the interstellar medium of the host galaxy, and find that the energy in the radio lobes can heat a significant fraction of the gas to the virial temperature. Finally, we discuss tests that may help future surveys distinguish between jet-driven kinematics and true black-hole binaries. J1517+3353 is a remarkable laboratory for AGN feedback and warrants deeper follow-up study. In the Appendix, we present high-resolution radio imaging of a second AGN with double-peaked [O III] lines, SDSS J112939.78+605742.6, which shows a sub-arcsecond radio jet. If the double-peaked nature of the narrow lines in radio-loud AGNs are generally due to radio jet interactions, we suggest that extended radio structure should be expected in most of such systems.NSF AST-0507483, AST-0808133University of Texas at AustinAlfred P. Sloan FoundationParticipating InstitutionsNational Aeronautics and Space AdministrationU.S. Department of EnergyJapanese MonbukagakushoMax Planck SocietyAstronom
Exploring the Conditional Effects of Bus Stops on Crime
Author's manuscript made available in accordance with the publisher's policy.Public transportation is a major element of social life in most cities, and the most common mode of public transportation is busing. This study examines whether bus stops are a robust predictor of crime, net of other factors, and whether the effect of bus stops on crime is conditioned by socioeconomic and land use factors. We use geocoded Indianapolis crime and bus stop data for 2010 to predict crime counts in 500-feet × 500-feet square grid cells, using negative binomial models. Net of other factors, bus stops are associated with variation in counts of Uniform Crime Reports reported rape, robbery, aggravated assault, burglary and larceny in a cell. In addition, the effect of bus stops on crime was conditioned by land use characteristics. In particular, the effect of bus stops on crime was greater in commercial and industrial areas, but dampened in areas with high-density residential housing
Experimental observations of dynamic critical phenomena in a lipid membrane
Near a critical point, the time scale of thermally-induced fluctuations
diverges in a manner determined by the dynamic universality class. Experiments
have verified predicted 3D dynamic critical exponents in many systems, but
similar experiments in 2D have been lacking for the case of conserved order
parameter. Here we analyze time-dependent correlation functions of a quasi-2D
lipid bilayer in water to show that its critical dynamics agree with a recently
predicted universality class. In particular, the effective dynamic exponent
crosses over from to as the correlation
length of fluctuations exceeds a hydrodynamic length set by the membrane and
bulk viscosities.Comment: 5 pages, 3 figures and 2 additional pages of supplemen
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