4,716 research outputs found
Reconciling diverse lacustrine and terrestrial system response to penultimate deglacial warming in southern Europe
Unlike the most recent deglaciation, the regional expression of climate changes during the penultimate deglaciation remains understudied, even though it led into a period of excess warmth with estimates of global average temperature 1–2 °C, and sea level ∼6 m, above pre-industrial values. We present the first complete high-resolution southern European diatom record capturing the penultimate glacial-interglacial transition, from Lake Ioannina (northwest Greece). It forms part of a suite of proxies selected to assess the character and phase relationships of terrestrial and aquatic ecosystem response to rapid climate warming, and to resolve apparent conflicts in proxy evidence for regional paleohydrology. The diatom data suggest a complex penultimate deglaciation driven primarily by multiple oscillations in lake level, and provide firm evidence for the regional influence of abrupt changes in North Atlantic conditions. There is diachroneity in lake and terrestrial ecosystem response to warming at the onset of the last interglacial, with an abrupt increase in lake level occurring ∼2.7 k.y. prior to sustained forest expansion with peak precipitation. We identify the potentially important role of direct input of snow melt and glacial meltwater transfer to the subterranean karst system in response to warming, which would cause rising regional groundwater levels. This explanation, and the greater sensitivity of diatoms to subtle changes in temperature, reconciles the divergent lacustrine and terrestrial proxy evidence and highlights the sensitivity of lakes situated in mountainous karstic environments to past climate warming
Examining the psychometric properties of the Behavioral Regulation in Exercise Questionnaire
The purpose of this study was to examine select psychometric properties of the Behavioral
Regulation in Exercise Questionnaire (BREQ; Mullen, Markland, &
Ingledew, 1997). To accomplish this aim, data were gathered in 2 phases to evaluate
the BREQ’s factorial composition and structure and the relation between the BREQ,
need satisfaction, exercise behavior, and relevant motivational constructs. Participants
completed measures assessing psychological need satisfaction, optimism, perceived
behavioral control, exercise behavior, and the BREQ. Phase 1 results supported
the original 4-factor measurement model and a simplex model of structural
relations between latentBREQconstructs suggested within self-determination theory
(Deci & Ryan, 1985), and results supported the positive relations between more
self-determined motives and greater psychological need satisfaction and frequent exercise
behavior. Phase 2 results provided further construct validity evidence for the
BREQ by linking subscale scores with greater perceived behavioral control in a manner
consistent with theory (Deci & Ryan, 1985). Collectively, these results further
support the construct validity of the BREQ and lend credence to the notion of measuring
exercise motivation from a multidimensional perspective using self-determination
theory as a guiding framework in the exercise domain
Resolved Mid-Infrared Emission Around AB Aur and V892 Tau with Adaptive Optics Nulling Interferometric Observations
We present the results of adaptive optics nulling interferometric
observations of two Herbig Ae stars, AB Aur and V892 Tau. Our observations at
10.3 microns show resolved circumstellar emission from both sources. Further
analysis of the AB Aur emission suggests that there is an inclined disk
surrounding the star. The diameter of the disk is derived to be 24 to 30 AU
with an inclination of 45 to 65 degrees from face-on, and a major-axis PA of 30
+/- 15 degrees (E of N). Differences in the physical characteristics between
the mid-IR emission and emission at other wavelengths (near-IR and millimeter),
found in previous studies, suggest a complex structure for AB Aur's
circumstellar environment, which may not be explained by a disk alone. The
similarity in the observed size of AB Aur's resolved emission and that of
another Herbig Ae star, HD 100546, is likely coincidental, as their respective
evolutionary states and spectral energy distributions suggest significantly
different circumstellar environments.Comment: 11 pages, 1 figure, Accepted for publication in ApJ Letter
Only connect: addressing the emotional needs of Scotland's children and young people
A report on the SNAP (Scottish Needs Assessment Programme) Child and Adolescent Mental Health Phase Two survey. It describes a survey of a wide range of professionals working with children and young people in Scotland, and deals with professional perspectives on emotional, behavioural and psychological problems. Conclusions and recommendations are presented
Single-shot Readout of a Superconducting Qubit using a Josephson Parametric Oscillator
We propose and demonstrate a new read-out technique for a superconducting
qubit by dispersively coupling it to a Josephson parametric oscillator. We
employ a tunable quarter-wavelength superconducting resonator and modulate its
resonant frequency at twice its value with an amplitude surpassing the
threshold for parametric instability. We map the qubit states onto two distinct
states of classical parametric oscillation: one oscillating state, with
photons in the resonator, and one with zero oscillation amplitude.
This high contrast obviates a following quantum-limited amplifier. We
demonstrate proof-of-principle, single-shot readout performance, and present an
error budget indicating that this method can surpass the fidelity threshold
required for quantum computing.Comment: 11 pages, 5 figure
Police Crime Arrests in the United States, 2011
Purpose – The purpose of the study is to provide empirical data on cases of police crime arrests during the year 2011. The study identifies and describes incidents in which nonfederal sworn law enforcement officers were arrested for one or more criminal offenses. Research Design & Method – The study is a quantitative content analysis of news articles identified through the Google News search engine using 48 automated Google Alerts queries. The unit of analysis in this study is criminal arrest case (not individual arrested officer). Intercoder Reliability – The Krippendorf’s alpha coefficient is strong (Krippendorf’s α = .9153) across the variables in the study. The overall level of simple percentage of agreement between coders across all of the variables (97.7%) also established a high degree of reliability. Research limitations/implications – The data are limited to cases that involve an official arrest. The data are also the result of a filtering process that includes the exercise of media discretion as to types of news stories reported and content devoted to particular news stories. Practical Implications – The study demonstrates that an annual report on police crime arrests can provide empirical data to better understand this neglected area of research. Originality/value – The study augments the few existing studies on the topic and is the only one known to describe the phenomenon in an annual report of police crime arrests as it occurs within law enforcement agencies nationwide
Genetic associations with childhood brain growth, defined in two longitudinal cohorts
Genome-wide association studies (GWASs) are unraveling the genetics of adult brain neuroanatomy as measured by cross-sectional anatomic magnetic resonance imaging (aMRI). However, the genetic mechanisms that shape childhood brain development are, as yet, largely unexplored. In this study we identify common genetic variants associated with childhood brain development as defined by longitudinal aMRI. Genome-wide single nucleotide polymorphism (SNP) data were determined in two cohorts: one enriched for attention-deficit/hyperactivity disorder (ADHD) (LONG cohort: 458 participants; 119 with ADHD) and the other from a population-based cohort (Generation R: 257 participants). The growth of the brain's major regions (cerebral cortex, white matter, basal ganglia, and cerebellum) and one region of interest (the right lateral prefrontal cortex) were defined on all individuals from two aMRIs, and a GWAS and a pathway analysis were performed. In addition, association between polygenic risk for ADHD and brain growth was determined for the LONG cohort. For white matter growth, GWAS meta-analysis identified a genome-wide significant intergenic SNP (rs12386571, P = 9.09 × 10-9 ), near AKR1B10. This gene is part of the aldo-keto reductase superfamily and shows neural expression. No enrichment of neural pathways was detected and polygenic risk for ADHD was not associated with the brain growth phenotypes in the LONG cohort that was enriched for the diagnosis of ADHD. The study illustrates the use of a novel brain growth phenotype defined in vivo for further study
Simulated VLBI Images From Relativistic Hydrodynamic Jet Models
A series of simulated maps showing the appearance in total intensity of flows
computed using a recently developed relativistic hydrodynamic code (Duncan \&
Hughes 1994: ApJ, 436, L119) are presented. The radiation transfer calculations
were performed by assuming the flow is permeated by a magnetic field and fast
particle distribution in energy equipartition, with energy density proportional
to the hydrodynamic energy density (i.e., pressure). We find that relativistic
flows subject to strong perturbations exhibit a density structure consisting of
a series of nested bow shocks, and that this structure is evident in the
intensity maps for large viewing angles. However, for viewing angles
, differential Doppler boosting leads to a series of axial knots
of emission, similar to the pattern exhibited by many VLBI sources. The
appearance of VLBI knots is determined primarily by the Doppler boosting of
parts of a more extended flow. To study the evolution of a perturbed jet, a
time series of maps was produced and an integrated flux light curve created.
The light curve shows features characteristic of a radio loud AGN: small
amplitude variations and a large outburst. We find that in the absence of
perturbations, jets with a modest Lorentz factor () exhibit complex
intensity maps, while faster jets (Lorentz factor ) are largely
featureless. We also study the appearance of kiloparsec jet-counterjet pairs by
producing simulated maps at relatively large viewing angles; we conclude that
observed hot spot emission is more likely to be associated with the Mach disk
than with the outer, bow shock.Comment: 27 pages, uses aasms4.sty; 18 PostScript figures (1.57Mb gziped,
8.67Mb gunziped) available from
http://www.astro.lsa.umich.edu/users/hughes/icon_dir/rad.html or by anonymous
ftp from ra.astro.lsa.umich.edu in pub/get/hughes. Submitted to Ap.
Measurement of the B0s Lifetime in the Flavor-Specific Decay Channel B0s→D−sμ+νX
We present an updated measurement of the B0s lifetime using the semileptonic decays B0s→D−sμ+νX, with D−s→ϕπ− and ϕ→K+K− (and the charge conjugate process). This measurement uses the full Tevatron Run II sample of proton-antiproton collisions at s√=1.96  TeV, comprising an integrated luminosity of 10.4  fb−1. We find a flavor-specific lifetime τfs(B0s)=1.479±0.010(stat)±0.021(syst)  ps. This technique is also used to determine the B0 lifetime using the analogous B0→D−μ+νX decay with D−→ϕπ− and ϕ→K+K−, yielding τ(B0)=1.534±0.019(stat)±0.021(syst)  ps. Both measurements are consistent with the current world averages, and the B0s lifetime measurement is one of the most precise to date. Taking advantage of the cancellation of systematic uncertainties, we determine the lifetime ratio τfs(B0s)/τ(B0)=0.964±0.013(stat)±0.007(syst)
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