14,845 research outputs found
Building a functional, integrated GIS/remote sensing resource analysis and planning system
To be an effective tool for resource analysis and planning, a geographic information system (GIS) needs to be integrated with a digital remote sensing capability. To be truly functional, the paired system must be driven by grass roots local needs. A case study couched in a Soil Conservation District in northern Utah is presented. Agency representatives determined that the most fundamental data sets to be entered into the GIS system analysis system in the first round were: land use/land cover; geomorphic/soil unit data; hydrologic unit data; and digital terrain. The least expensive and best ways to obtain these data were determined. Data were acquired and formatted to enter the state's PRIME/ARC-INFO GIS, and are being interrogated for resource management decisions related to such issues as agricultural preservation, urban expansion, soil erosion control, and dam siting
Modelling temperature-dependent larval development and\ud subsequent demographic Allee effects in adult populations of the alpine butterfly Parnassius smintheus
Climate change has been attributed as a driver of changes to ecological systems worldwide and understanding the effects of climate change at individual, population, community, and ecosystem levels has become a primary concern of ecology. One avenue toward understanding the impacts of climate change on an ecosystem is through the study of environmentally sensitive species. Butterflies are sensitive to climatic changes due to their reliance on environmental cues such as temperature and photoperiod, which regulate the completion of life history stages. As such, the population dynamics of butterflies may offer insight into the impacts of climate change on the health of an ecosystem. In this paper we study the effects of rearing temperature on the alpine butterfly Parnassius smintheus (Rocky Mountain Apollo), both directly through individual phenological changes and indirectly through adult reproductive success at the population level. Our approach is to formulate a mathematical model of individual development parameterized by experimental data and link larval development to adult reproductive success. A Bernoulli process model describes temperature-dependent larval phenology, and a system of ordinary differential equations is used to study impacts on reproductive success. The phenological model takes field temperature data as its input and predicts a temporal distribution of adult emergence, which in turn controls the dynamics of the reproductive success model. We find that warmer spring and summer temperatures increase reproductive success, while cooler temperatures exacerbate a demographic Allee effect, suggesting that observed yearly fluctuations in P. smintheus population size may be driven by inter-annual temperature variability. Model predictions are validated against mark-recapture field data from 2001 and 2003 − 2009
Enhanced noise at high bias in atomic-scale Au break junctions
Heating in nanoscale systems driven out of equilibrium is of fundamental
importance, has ramifications for technological applications, and is a
challenge to characterize experimentally. Prior experiments using nanoscale
junctions have largely focused on heating of ionic degrees of freedom, while
heating of the electrons has been mostly neglected. We report measurements in
atomic-scale Au break junctions, in which the bias-driven component of the
current noise is used as a probe of the electronic distribution. At low biases
( 150~mV) the noise is consistent with expectations of shot noise at a fixed
electronic temperature. At higher biases, a nonlinear dependence of the noise
power is observed. We consider candidate mechanisms for this increase,
including flicker noise (due to ionic motion), heating of the bulk electrodes,
nonequilibrium electron-phonon effects, and local heating of the electronic
distribution impinging on the ballistic junction. We find that flicker noise
and bulk heating are quantitatively unlikely to explain the observations. We
discuss the implications of these observations for other nanoscale systems, and
experimental tests to distinguish vibrational and electron interaction
mechanisms for the enhanced noise.Comment: 30 pages, 7 figure
Phase Space Formulation of Quantum Mechanics. Insight into the Measurement Problem
A phase space mathematical formulation of quantum mechanical processes
accompanied by and ontological interpretation is presented in an axiomatic
form. The problem of quantum measurement, including that of quantum state
filtering, is treated in detail. Unlike standard quantum theory both quantum
and classical measuring device can be accommodated by the present approach to
solve the quantum measurement problemComment: 29 pages, 4 figure
Vacuum state of the quantum string without anomalies in any number of dimensions
We show that the anomalies of the Virasoro algebra are due to the asymmetric
behavior of raising and lowering operators with respect to the ground state of
the string. With the adoption of a symmetric vacuum we obtain a non-anomalous
theory in any number of dimensions. In particular for D=4.Comment: 14 pages, LaTex, no figure
Phase field modeling of electrochemistry II: Kinetics
The kinetic behavior of a phase field model of electrochemistry is explored
for advancing (electrodeposition) and receding (electrodissolution) conditions
in one dimension. We described the equilibrium behavior of this model in [J. E.
Guyer, W. J. Boettinger, J.A. Warren, and G. B. McFadden, ``Phase field
modeling of electrochemistry I: Equilibrium'', cond-mat/0308173]. We examine
the relationship between the parameters of the phase field method and the more
typical parameters of electrochemistry. We demonstrate ohmic conduction in the
electrode and ionic conduction in the electrolyte. We find that, despite making
simple, linear dynamic postulates, we obtain the nonlinear relationship between
current and overpotential predicted by the classical ``Butler-Volmer'' equation
and observed in electrochemical experiments. The charge distribution in the
interfacial double layer changes with the passage of current and, at
sufficiently high currents, we find that the diffusion limited deposition of a
more noble cation leads to alloy deposition with less noble species.Comment: v3: To be published in Phys. Rev. E v2: Attempt to work around
turnpage bug. Replaced color Fig. 4a with grayscale 13 pages, 7 figures in 10
files, REVTeX 4, SIunits.sty, follows cond-mat/030817
Non-analytical power law correction to the Einstein-Hilbert action: gravitational wave propagation
We analyze the features of the Minkowskian limit of a particular
non-analytical f(R) model, whose Taylor expansion in the weak field limit does
not hold, as far as gravitational waves (GWs) are concerned. We solve the
corresponding Einstein equations and we find an explicit expression of the
modified GWs as the sum of two terms, i.e. the standard one and a modified
part. As a result, GWs in this model are not transverse, and their polarization
is different from that of General Relativity. The velocity of the GW modified
part depends crucially on the parameters characterizing the model, and it
mostly results much smaller than the speed of light. Moreover, this
investigation allows one to further test the viability of this particular f(R)
gravity theory as far as interferometric observations of GWs are concerned.Comment: 18 pages, 3 figure
Wigner-Yanase skew information as tests for quantum entanglement
A Bell-type inequality is proposed in terms of Wigner-Yanase skew
information, which is quadratic and involves only one local spin observable at
each site. This inequality presents a hierarchic classification of all states
of multipartite quantum systems from separable to fully entangled states, which
is more powerful than the one presented by quadratic Bell inequalities from
two-entangled to fully entangled states. In particular, it is proved that the
inequality provides an exact test to distinguish entangled from nonentangled
pure states of two qubits. Our inequality sheds considerable light on
relationships between quantum entanglement and information theory.Comment: 5 page
Renal fibrosis in feline chronic kidney disease: known mediators and mechanisms of injury
Chronic kidney disease (CKD) is a common medical condition of ageing cats. In most cases the underlying aetiology is unknown, but the most frequently reported pathological diagnosis is renal tubulointerstitial fibrosis. Renal fibrosis, characterised by extensive accumulation of extra-cellular matrix within the interstitium, is thought to be the final common pathway for all kidney diseases and is the pathological lesion best correlated with function in both humans and cats. As a convergent pathway, renal fibrosis provides an ideal target for the treatment of CKD and knowledge of the underlying fibrotic process is essential for the future development of novel therapies. There are many mediators and mechanisms of renal fibrosis reported in the literature, of which only a few have been investigated in the cat. This article reviews the process of renal fibrosis and discusses the most commonly cited mediators and mechanisms of progressive renal injury, with particular focus on the potential significance to feline CKD
- …