23,615 research outputs found
Strategic Group Analysis of U.S. Food Businesses Using the Two-step Clustering Method
strategic group, planning, strategy, performance, Agribusiness, Institutional and Behavioral Economics, Marketing, Productivity Analysis, M0, M14, M2, M30,
Thermal expansion of liquid Ti–6Al–4V measured by electrostatic levitation
The liquid density of Ti–6Al–4V was measured over a temperature range from 1661 to 1997 K that included undercooling by as much as 280 K. The sample was levitated in an electrostatic levitator and video imaging technique was used to capture the volume changes as a function of temperature. Over the temperature range the liquid density can be expressed by rholiq(T)=4123–0.254 (T–Tm) kg/m^3, where the melting temperature Tm is 1943 K. The corresponding volume expansion coefficient is alphaliq=6.05×10^–5 K^–1 near Tm
What is the Value of Public Goods Generated by a National Football League Team: A CVM Approach
Using the Contingent Valuation Method, this paper estimates the value of public goods the National Football League’s Jaguars produce for Jacksonville, Florida, including the value of elevating Jacksonville to major league status. It also estimates the incremental value of public goods potentially produced by a National Basketball Association team in Jacksonville. The present value of public goods created by the Jaguars is 12.7 million. Sports public goods probably cannot justify the large public expenditures on stadiums and arenas.
Frequency-dependent attenuation and elasticity in unconsolidated earth materials: effect of damping
We use the Discrete Element Method (DEM) to understand the underlying
attenuation mechanism in granular media, with special applicability to the
measurements of the so-called effective mass developed earlier. We consider
that the particles interact via Hertz-Mindlin elastic contact forces and that
the damping is describable as a force proportional to the velocity difference
of contacting grains. We determine the behavior of the complex-valued normal
mode frequencies using 1) DEM, 2) direct diagonalization of the relevant
matrix, and 3) a numerical search for the zeros of the relevant determinant.
All three methods are in strong agreement with each other. The real and the
imaginary parts of each normal mode frequency characterize the elastic and the
dissipative properties, respectively, of the granular medium. We demonstrate
that, as the interparticle damping, , increases, the normal modes exhibit
nearly circular trajectories in the complex frequency plane and that for a
given value of they all lie on or near a circle of radius centered on
the point in the complex plane, where . We show that each
normal mode becomes critically damped at a value of the damping parameter , where is the (real-valued) frequency when
there is no damping. The strong indication is that these conclusions carry over
to the properties of real granular media whose dissipation is dominated by the
relative motion of contacting grains. For example, compressional or shear waves
in unconsolidated dry sediments can be expected to become overdamped beyond a
critical frequency, depending upon the strength of the intergranular damping
constant.Comment: 28 pages, 7 figure
Tolerability, safety, and efficacy of adjunctive brivaracetam for focal seizures in older patients: A pooled analysis from three phase III studies
Introduction:
This analysis was conducted to assess the tolerability, safety, and efficacy of brivaracetam (BRV) for adjunctive treatment of focal (partial-onset) seizures in patients aged ≥65 years.
Methods:
Safety/tolerability and efficacy data for patients aged ≥65 years were pooled from three randomized, double-blind, placebo-controlled, fixed-dose Phase III studies (NCT00490035, NCT00464269, and NCT01261325). Data were pooled by treatment group: placebo or the proposed therapeutic dose range of 50–200 mg/day: BRV 50, 100, 200 mg/day.
Results:
Thirty-two patients aged ≥65 years were randomized to placebo or BRV 50–200 mg/day. Of these, 30 patients (93.8%) completed their respective study. In the safety population (n = 32), 87.5% placebo- vs 73.3% BRV-treated patients reported treatment-emergent adverse events (TEAEs) during the treatment period; most commonly, headache (25.0% vs 12.5%), paresthesia (0% vs 12.5%), and somnolence (50.0% vs 12.5%) for placebo- vs BRV-treated patients, respectively. During the treatment period, drug-related TEAEs were reported by 62.5% of placebo- vs 53.3% of BRV-treated patients, and serious TEAEs (SAEs) were reported by 0% of placebo- and 4.2% of BRV-treated patients; there were no drug-related SAEs and no deaths. Three SAEs (placebo 1/8; BRV 2/24) and two deaths (placebo 1/8; BRV 1/24) occurred in the post-treatment period. In the efficacy population (n = 31), median percent reduction from baseline in focal seizure frequency/28 days was 14.0% for placebo vs 25.5%, 49.6%, and 74.9% for BRV 50, 100, and 200 mg/day, respectively. The ≥50% responder rate was 14.3% for placebo vs 25.0%, 50.0%, and 66.7% for BRV 50, 100, and 200 mg/day, respectively.
Conclusions:
Safety/tolerability and efficacy findings in this small subgroup of older patients treated with adjunctive BRV are consistent with those observed in the much larger overall pooled population. BRV may be a suitable adjunctive treatment for older patients with uncontrolled focal seizures. Further larger studies in this population are warranted
Transit Analysis Package (TAP and autoKep): IDL Graphical User Interfaces for Extrasolar Planet Transit Photometry
We present an IDL graphical user interface-driven software package designed
for the analysis of extrasolar planet transit light curves. The Transit
Analysis Package (TAP) software uses Markov Chain Monte Carlo (MCMC) techniques
to fit light curves using the analytic model of Mandel and Agol (2002). The
package incorporates a wavelet based likelihood function developed by Carter
and Winn (2009) which allows the MCMC to assess parameter uncertainties more
robustly than classic chi-squared methods by parameterizing uncorrelated
"white" and correlated "red" noise. The software is able to simultaneously
analyze multiple transits observed in different conditions (instrument, filter,
weather, etc). The graphical interface allows for the simple execution and
interpretation of Bayesian MCMC analysis tailored to a user's specific data set
and has been thoroughly tested on ground-based and Kepler photometry. AutoKep
provides a similar GUI for the preparation of Kepler MAST archive data for
analysis by TAP or any other analysis software. This paper describes the
software release and provides instructions for its use.Comment: 8 pages, 2 figure
A General Theory of Emergence in Engineered Systems
Engineered systems are designed to satisfy specific needs and produce explainable/predictable results. But despite this intent, engineered systems don’t always do what they are designed to do once they are implemented. Some engineered systems produce properties and behaviors that are not clearly explainable or predictable by the properties of their components. This is a problem recognized in government and private sectors as having broad ranging financial and security consequences. It is also the essence of the emergence phenomena. A review of the literature reveals two significant gaps in the current body of knowledge on emergence as it pertains to engineered systems: 1) no conceptual model that reconciles conflicting aspects of emergence; and 2) no explanation of system factors and their relationships that affect the occurrence of emergence. The gaps are addressed in this dissertation through research using a methodology that incorporates rationalist inductive methods with modeling & simulation frameworks. Where other research and models of emergence focus on entity or agent behavior; the research in this dissertation takes place from a systems perspective. The focus is on system level behaviors and system factors as they pertain to the occurrence of emergent effects. Generally accepted thermodynamic principles and axioms for chemical reactions are used to develop scientific analogies for factors in engineered systems. A theory is derived consisting of six factors that are determinants in a mathematical model of a tipping point at which emergent effects will occur in engineered systems: 1) interoperability; 2) concentration of components; 3) component degrees of freedom; 4) variety of system regulators; 5) rate of information received vs transmitted by the system; and 6) relative amount of information received by the system vs a threshold for change in the system configuration. The theory and its implications are explored in simulation experiments. Other products and contributions of the research include: a) an ontology of emergence concepts; b) a unifying definition of emergence; and c) a system dynamics model of emergence in engineered systems
Newly-Discovered Planets Orbiting HD~5319, HD~11506, HD~75784 and HD~10442 from the N2K Consortium
Initially designed to discover short-period planets, the N2K campaign has
since evolved to discover new worlds at large separations from their host
stars. Detecting such worlds will help determine the giant planet occurrence at
semi-major axes beyond the ice line, where gas giants are thought to mostly
form. Here we report four newly-discovered gas giant planets (with minimum
masses ranging from 0.4 to 2.1 MJup) orbiting stars monitored as part of the
N2K program. Two of these planets orbit stars already known to host planets: HD
5319 and HD 11506. The remaining discoveries reside in previously-unknown
planetary systems: HD 10442 and HD 75784. The refined orbital period of the
inner planet orbiting HD 5319 is 641 days. The newly-discovered outer planet
orbits in 886 days. The large masses combined with the proximity to a 4:3 mean
motion resonance make this system a challenge to explain with current formation
and migration theories. HD 11506 has one confirmed planet, and here we confirm
a second. The outer planet has an orbital period of 1627.5 days, and the
newly-discovered inner planet orbits in 223.6 days. A planet has also been
discovered orbiting HD 75784 with an orbital period of 341.7 days. There is
evidence for a longer period signal; however, several more years of
observations are needed to put tight constraints on the Keplerian parameters
for the outer planet. Lastly, an additional planet has been detected orbiting
HD 10442 with a period of 1043 days.Comment: Accepted for publication in Ap
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