113,633 research outputs found
Recent Surge in Homicides Involving Young Black Males and Guns: Time To Reinvest in Prevention and Crime Control
This review of recent U.S. homicide trends by race of offenders and victims, as well as weapons used, shows a surge in homicides that involve young Black males and guns
Simplified PBEE to Estimate Economic Seismic Risk for Buildings
A seismic risk assessment is often performed on behalf of a buyer of large commercial
buildings in seismically active regions. One outcome of the assessment is that a probable
maximum loss (PML) is computed. PML is of limited use to real-estate investors as it has no
place in a standard financial analysis and reflects too long a planning period for what-if
scenarios. We introduce an alternative to PML called probable frequent loss (PFL), defined as
the mean loss resulting from an economic-basis earthquake such as shaking with 10%
exceedance probability in 5 years. PFL is approximately related to expected annualized loss
(EAL) through a site economic hazard coefficient (H) introduced here. PFL and EAL offer three
advantages over PML: (1) meaningful planning period; (2) applicability in financial analysis
(making seismic risk a potential market force); and (3) can be estimated by a rigorous but
simplified PBEE method that relies on a single linear structural analysis. We illustrate using 15
example buildings, including a 7-story nonductile reinforced-concrete moment-frame building
in Van Nuys, CA and 14 buildings from the CUREE-Caltech Woodframe Project
The Hazen Mammoth (Mammuthus columbi), Prairie County, Arkansas
In May 1965, mammoth remains were exposed during the excavation of a borrow pit for construction of Interstate Highway 40, 2 mi northeast of Hazen, Prairie County, Arkansas. The proboscidian remains consisted of a skull with tusks, mandibles, atlas and other skeletal elements. The vertebra material was scattered over approximately 150 m (1,600 sq ft) but was confined to a layer of red clayey-silt 6.7 m (22 ft) below the surface. No additional fauna or flora was recovered. The mammoth remains are referred to Mammuthus columbi (Falconer, 1857) on the basis of characteristics of the dentition, particularly the comparison of index of hypsodonty to functional plate density. Mammuthus columbi was widely distributed in southeast North America during the late part of the Pleistocene Epoch (Sangamon-Wisconsin Stages)
Towards an exact reconstruction of a time-invariant model from time series data
Dynamic processes in biological systems may be profiled by measuring system properties over time. One way of representing such time series data is through weighted interaction networks, where the nodes in the network represent the measurables and the weighted edges represent interactions between any pair of nodes. Construction of these network models from time series data may involve seeking a robust data-consistent and time-invariant model to approximate and describe system dynamics. Many problems in mathematics, systems biology and physics can be recast into this form and may require finding the most consistent solution to a set of first order differential equations. This is especially challenging in cases where the number of data points is less than or equal to the number of measurables. We present a novel computational method for network reconstruction with limited time series data. To test our method, we use artificial time series data generated from known network models. We then attempt to reconstruct the original network from the time series data alone. We find good agreement between the original and predicted networks
Investigation of Metal and Organic Contaminant Distributions and Sedimentation Rates in Backwater Lakes along the Illinois River
Systematic sub-sampling of sediment cores in sections of uniform thickness is necessary
in order to evaluate historic changes in sediment quality, to determine the vertical extent
of contamination, and to measure sedimentation rates. With these objectives in mind,
fourteen sediment cores were collected during March 2002 using the Illinois State Water
Survey vibracorer. Concentrations of metals and total organic carbon were measured
using standard techniques. Concentrations of chlorinated pesticides, phenolic compounds,
polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs) were
measured by gas chromatography/mass spectrometry (GC-MS). The concentrations of
chlorinated pesticides, phenolic compounds and polychlorinated biphenyls (PCBs) were
below the method detection limit in all sediment samples analyzed. However, there was
a wide range in concentrations of polycyclic aromatic hydrocarbons (PAHs) which were
detected in all sediment samples. Also, a wide range of metal concentrations was noted
in the sediments evaluated. Lower concentrations of metals were found in the upper 0.5
m of sediment but concentrations were elevated at depths ranging from 1.0 m to 1.5 m.
Sedimentation rates were estimated using cesium-137 radiometric dating on 14
vibracores. Sedimentation rates range from < 0.1 to 1.9 cm/yr, with an average of 0.9
cm/yr. These rates are comparable to those reported in previous studies.Illinois Sustainable Technology Centerpublished or submitted for publicationis peer reviewe
Amplitude death criteria for coupled complex Ginzburg-Landau systems
Amplitude death, which occurs in a system when one or more macroscopic
wavefunctions collapse to zero, has been observed in mutually coupled
solid-state lasers, analog circuits, and thermoacoustic oscillators, to name a
few applications. While studies have considered amplitude death on oscillator
systems and in externally forced complex Ginzburg-Landau systems, a route to
amplitude death has not been studied in autonomous continuum systems. We derive
simple analytic conditions for the onset of amplitude death of one macroscopic
wavefunction in a system of two coupled complex Ginzburg-Landau equations with
general nonlinear self- and cross-interaction terms. Our results give a more
general theoretical underpinning for recent amplitude death results reported in
the literature, and suggest an approach for tuning parameters in such systems
so that they either permit or prohibit amplitude death of a wavefunction
(depending on the application). Numerical simulation of the coupled complex
Ginzburg-Landau equations, for examples including cubic, cubic-quintic, and
saturable nonlinearities, is used to illustrate the analytical results.Comment: 7 pages, 4 figure
Intermittent Synchronization in a Pair of Coupled Chaotic Pendula
Numerical simulations have been carried out for a pair of unidirectionally coupled identical pendula under the action of a common external ac torque. Both the master pendulum and the slave pendulum were in chaotic states. The only form of persistent locking appeared to be a computational artifact; otherwise the synchronization of slave to master was found to be intermittent
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