1,792 research outputs found
Contextual factors among indiscriminate or larger attacks on food or water supplies, 1946-2015
This research updates previous inventories of malicious attacks on food and water to include data from 1946 through mid-2015. A systematic search of news reports, databases and previous inventories of poisoning events was undertaken. Incidents that threatened or were intended to achieve direct harm to humans, and that were either relatively large (number of victims > 4 or indiscriminate in intent or realisation were included. Agents could be chemical, biological or radio-nuclear. Reports of candidate incidents were subjected to systematic inclusion and exclusion criteria as well as validity analysis (not always clearly undertaken in previous inventories of such attacks). We summarise contextual aspects of the attacks that may be important for scenario prioritisation, modelling and defensive preparedness. Opportunity is key to most realised attacks, particularly access to dangerous agents. The most common motives and relative success rate in causing harm were very different between food and water attacks. The likelihood that people were made ill or died also varied by food/water mode, and according to motive and opportunity for delivery of the hazardous agent. Deaths and illness associated with attacks during food manufacture and prior to sale have been fewer than those in some other contexts. Valuable opportunities for food defence improvements are identified in other contexts, especially food prepared in private or community settings
Worst Case Resistance Testing: A Nonresponse Bias Solution for Today's Behavioral Research Realities
This study proposes a method of nonresponse assessment based on
meta-analytical file-drawer techniques, also known as worst-case resistance
testing (WCRT), and suitable for a wide range of data collection scenarios. A
general method is devised to estimate the number of significantly different
nonrespondents it would take to significantly alter the results of an analysis.
Estimates of nonrespondents can be plotted against effect sizes using
"n-curves", with similar interpretation to p-curves or power curves. Variants
of the general method are derived for tests of means and correlations. A sample
using a well-established survey instrument from previous behavioral research is
used to test the method. The results suggest that employing worst-case
resistance testing can be used on its own or in conjunction with wave analysis
to precisely flag nonresponse risks
Quantum calculations of Coulomb reorientation for sub-barrier fusion
Classical mechanics and Time Dependent Hartree-Fock (TDHF) calculations of
heavy ions collisions are performed to study the rotation of a deformed nucleus
in the Coulomb field of its partner. This reorientation is shown to be
independent on charges and relative energy of the partners. It only depends
upon the deformations and inertias. TDHF calculations predict an increase by
30% of the induced rotation due to quantum effects while the nuclear
contribution seems negligible. This reorientation modifies strongly the fusion
cross-section around the barrier for light deformed nuclei on heavy collision
partners. For such nuclei a hindrance of the sub-barrier fusion is predicted.Comment: accepted for publication in Physical Review Lette
On the Significance of Absorption Features in HST/COS Data
We present empirical scaling relations for the significance of absorption
features detected in medium resolution, far-UV spectra obtained with the Cosmic
Origins Spectrograph (COS). These relations properly account for both the
extended wings of the COS line spread function and the non-Poissonian noise
properties of the data, which we characterize for the first time, and predict
limiting equivalent widths that deviate from the empirical behavior by \leq 5%
when the wavelength and Doppler parameter are in the ranges \lambda = 1150-1750
A and b > 10 km/s. We have tested a number of coaddition algorithms and find
the noise properties of individual exposures to be closer to the Poissonian
ideal than coadded data in all cases. For unresolved absorption lines, limiting
equivalent widths for coadded data are 6% larger than limiting equivalent
widths derived from individual exposures with the same signal-to-noise. This
ratio scales with b-value for resolved absorption lines, with coadded data
having a limiting equivalent width that is 25% larger than individual exposures
when b \approx 150 km/s.Comment: 25 pages, 3 tables, 7 figures, accepted for publication in PAS
The Study on Cracking Strength of AIJs to Release the Early-Age Stress of Mass Concrete
This paper aims to theoretically and numerically assess the effect of setting artificial-induced joints (AIJs) during construction period of amass concrete structure to release the early-stage thermal stress. With respect to the coupling influences of various factors such as size and boundary of AIJs, an analytical model for its cracking strength on the setting section of mass concrete is proposed based on double-parameter fracture theory. A kind of hyper-finite element analysis (FEA) for many array AIJs in simplified plane pate is also presented by using bilinear cohesive force distribution. The results from the present model and numerical simulation were compared to those of experimental data to prove the efficiency and accuracy of the analytical model and FEA. The model presented in this study for the cracking strength of AIJs provides a simple useful tool to accurately evaluate how many early stress AIJs reduced. The theoretical solution and FEA results could also be significantly contributed to find the "just" and "perfect" release of the temperature stress and to improve the design level of AIJs in mass concrete structure
Beta-decay branching ratios of 62Ga
Beta-decay branching ratios of 62Ga have been measured at the IGISOL facility
of the Accelerator Laboratory of the University of Jyvaskyla. 62Ga is one of
the heavier Tz = 0, 0+ -> 0+ beta-emitting nuclides used to determine the
vector coupling constant of the weak interaction and the Vud quark-mixing
matrix element. For part of the experimental studies presented here, the
JYFLTRAP facility has been employed to prepare isotopically pure beams of 62Ga.
The branching ratio obtained, BR= 99.893(24)%, for the super-allowed branch is
in agreement with previous measurements and allows to determine the ft value
and the universal Ft value for the super-allowed beta decay of 62Ga
Life Beyond the Solar System: Space Weather and Its Impact on Habitable Worlds
The search of life in the Universe is a fundamental problem of astrobiology
and a major priority for NASA. A key area of major progress since the NASA
Astrobiology Strategy 2015 (NAS15) has been a shift from the exoplanet
discovery phase to a phase of characterization and modeling of the physics and
chemistry of exoplanetary atmospheres, and the development of observational
strategies for the search for life in the Universe by combining expertise from
four NASA science disciplines including heliophysics, astrophysics, planetary
science and Earth science. The NASA Nexus for Exoplanetary System Science
(NExSS) has provided an efficient environment for such interdisciplinary
studies. Solar flares, coronal mass ejections and solar energetic particles
produce disturbances in interplanetary space collectively referred to as space
weather, which interacts with the Earth upper atmosphere and causes dramatic
impact on space and ground-based technological systems. Exoplanets within close
in habitable zones around M dwarfs and other active stars are exposed to
extreme ionizing radiation fluxes, thus making exoplanetary space weather (ESW)
effects a crucial factor of habitability. In this paper, we describe the recent
developments and provide recommendations in this interdisciplinary effort with
the focus on the impacts of ESW on habitability, and the prospects for future
progress in searching for signs of life in the Universe as the outcome of the
NExSS workshop held in Nov 29 - Dec 2, 2016, New Orleans, LA. This is one of
five Life Beyond the Solar System white papers submitted by NExSS to the
National Academy of Sciences in support of the Astrobiology Science Strategy
for the Search for Life in the Universe.Comment: 5 pages, the white paper was submitted to the National Academy of
Sciences in support of the Astrobiology Science Strategy for the Search for
Life in the Univers
Hysteresis and hierarchies: dynamics of disorder-driven first-order phase transformations
We use the zero-temperature random-field Ising model to study hysteretic
behavior at first-order phase transitions. Sweeping the external field through
zero, the model exhibits hysteresis, the return-point memory effect, and
avalanche fluctuations. There is a critical value of disorder at which a jump
in the magnetization (corresponding to an infinite avalanche) first occurs. We
study the universal behavior at this critical point using mean-field theory,
and also present preliminary results of numerical simulations in three
dimensions.Comment: 12 pages plus 2 appended figures, plain TeX, CU-MSC-747
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