4,758 research outputs found
Addressing Uncertainty in TMDLS: Short Course at Arkansas Water Resources Center 2001 Annual Conference
Management of a critical natural resource like water requires information on the status of that resource. The US Environmental Protection Agency (EPA) reported in the 1998 National Water Quality Inventory that more than 291,000 miles of assessed rivers and streams and 5 million acres of lakes do not meet State water quality standards. This inventory represents a compilation of State assessments of 840,000 miles of rivers and 17.4 million acres of lakes; a 22 percent increase in river miles and 4 percent increase in lake acres over their 1996 reports. Siltation, bacteria, nutrients and metals were the leading pollutants of impaired waters, according to EPA. The sources of these pollutants were presumed to be runoff from agricultural lands and urban areas. EPA suggests that the majority of Americans-over 218 million-live within ten miles of a polluted waterbody. This seems to contradict the recent proclamations of the success of the Clean Water Act, the Nation\u27s water pollution control law. EPA also claims that, while water quality is still threatened in the US, the amount of water safe for fishing and swimming has doubled since 1972, and that the number of people served by sewage treatment plants has more than doubled
Proposing Standards for Child Custody: The Proceedings, the Role of the Agency, and the Best Interests of the Child
Article discusses the nature of child custody proceedings, the roles of the court and the parties, and the standards which the courts will apply in determining the custody of the child under the standard of “best interests” of the child. Article proposes that legislature should amend section 614 of the Family Court Act and section 384(b) of the Social Services Law to state clearly whether the “best interest of the child” test has any relevancy at the fact-finding stage, or whether there must be an independent finding at the fact-finding hearing of neglect or fault on the part of the parent before the best interest of the child test is applied at the dispositional hearing
Fragments of ML Decidable by Nested Data Class Memory Automata
The call-by-value language RML may be viewed as a canonical restriction of
Standard ML to ground-type references, augmented by a "bad variable" construct
in the sense of Reynolds. We consider the fragment of (finitary) RML terms of
order at most 1 with free variables of order at most 2, and identify two
subfragments of this for which we show observational equivalence to be
decidable. The first subfragment consists of those terms in which the
P-pointers in the game semantic representation are determined by the underlying
sequence of moves. The second subfragment consists of terms in which the
O-pointers of moves corresponding to free variables in the game semantic
representation are determined by the underlying moves. These results are shown
using a reduction to a form of automata over data words in which the data
values have a tree-structure, reflecting the tree-structure of the threads in
the game semantic plays. In addition we show that observational equivalence is
undecidable at every third- or higher-order type, every second-order type which
takes at least two first-order arguments, and every second-order type (of arity
greater than one) that has a first-order argument which is not the final
argument
Fast Magnetic Twister and Plasma Perturbations in a 3-D Coronal Arcade
We present results of 3-D numerical simulations of a fast magnetic twister
excited above a foot-point of the potential solar coronal arcade that is
embedded in the solar atmosphere with the initial VAL-IIIC temperature profile,
which is smoothly extended into the solar corona. With the use of the FLASH
code, we solve 3-D ideal magnetohydrodynamic equations by specifying a twist in
the azimuthal component of magnetic field in the solar chromosphere. The
imposed perturbation generates torsional Alfv\'en waves as well as plasma
swirls that reach the other foot-point of the arcade and partially reflect back
from the transition region. The two vortex channels are evident in the
generated twisted flux-tube with a fragmentation near its apex that results
from the initial twist as well as from the morphology of the tube. The
numerical results are compared to observational data of plasma motions in a
solar prominence. The comparison shows that the numerical results and the data
qualitatively agree even though the observed plasma motions occur over
comparatively large spatio-temporal scales in the prominence.Comment: 26 pages; 7 Figures; Ap
A man in Mikhail Osorgin’s concept of time
The main subject of the article is the way Mikhail Osorgin perceives the relation between man and time in his emigration novels. The category of time in Osorgin’s works cannot be considered apart from the human factor. Osorgin has always been interested in man’s role and place in the eternal stream of time.The main subject of the article is the way Mikhail Osorgin perceives the relation between man and time in his emigration novels. The category of time in Osorgin’s works cannot be considered apart from the human factor. Osorgin has always been interested in man’s role and place in the eternal stream of time.The main subject of the article is the way Mikhail Osorgin perceives the relation between man and time in his emigration novels. The category of time in Osorgin’s works cannot be considered apart from the human factor. Osorgin has always been interested in man’s role and place in the eternal stream of time
Monte Carlo study of phase separation in magnetic insulators
In this work we focus on the study of phase separation in the zero-bandwidth
extended Hubbard with nearest-neighbors intersite Ising-like magnetic
interactions and on-site Coulomb interactions . The system has been
analyzed by means of Monte Carlo simulations (in the grand canonical ensemble)
on two dimensional square lattice (with sites) and the
results for as a function of chemical potential and electron
concentration have been obtained. Depending on the values of interaction
parameters the system exhibits homogeneous (anti-)ferromagnetic (AF) or
non-ordered (NO) phase as well as phase separation PS:AF/NO state. Transitions
between homogeneous phases (i.e. AF-NO transitions) can be of first or second
order and the tricritical point is also present on the phase diagrams. The
electron compressibility is an indicator of the phase separation and that
quantity is of particular interest of this paper.Comment: 4 pages, 3 figures; pdf-ReVTeX; updated references; presented at The
European Conference PHYSICS OF MAGNETISM 2014 (PM'14), June 23-27, 2014,
Poznan, Poland; submitted to Acta Physica Polonica
Fast magnetoacoustic wave trains in magnetic funnels of the solar corona
Context: Fast magneto-acoustic waves are highly dispersive in waveguides, so they can generate quasi-periodic wave trains if a localised, impulsive driver is applied. Such wave trains have been observed in the solar corona and may be of use as a seismological tool since they depend upon the plasma structuring perpendicular to the direction of propagation.
Aims. We extend existing models of magnetoacoustic waveguides to consider the effects of an expanding magnetic field. The funnel geometry employed includes a field-aligned density structure.
Methods: We performed 2D numerical simulations of impulsively generated fast magneto-acoustic perturbations. The effects of the density contrast ratio, density stratification, and spectral profile of the driver upon the excited wave trains were investigated.
Results: The density structure acts as a dispersive waveguide for fast magneto-acoustic waves and generates a quasi-periodic wave train similar to previous models. The funnel geometry leads to generating additional wave trains that propagate outside the density structure. These newly discovered wave trains are formed by the leakage of transverse perturbations, but they propagate upwards owing to the refraction caused by the magnetic funnel.
Conclusions: The results of our funnel model may be applicable to wave trains observed propagating in the solar corona. They demonstrate similar properties to those found in our simulations
Bisimilarity of Pushdown Systems is Nonelementary
Given two pushdown systems, the bisimilarity problem asks whether they are
bisimilar. While this problem is known to be decidable our main result states
that it is nonelementary, improving EXPTIME-hardness, which was the previously
best known lower bound for this problem. Our lower bound result holds for
normed pushdown systems as well
Uncertain Memory
"Uncertain Memory" features a series of figurative oil paintings on canvas and paper inspired by photographs from my family archive. My paintings are developed in stages; beginning with a process of mining and selecting specific images, which are then manipulated before being translated into paintings as works on paper or canvas. I focus primarily on female figures as I search for a sense of strangeness within each image as well as an uncertainty about the figure’s actions or whereabouts in the scene. I am drawn to ambiguity as a means of exploring relationships between past and present, reflecting a personal need to establish a sense of identity and understanding of my family’s past, as well as examining the universal and intimate relationship we have to photographic images
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