16,929 research outputs found
Macromia alleghaniensis (Odonata: Macromiidae): New For Michigan, with Clarifications of Northern Records
An Alleghany River Cruiser, Macromia alleghaniensis Williamson (Odonata: Macromiidae), collected in Cass County, Michigan on 18 June 2014, represents the first record of the species for the state, as well as the northernmost unequivocal record in North America. Other records north of 40° latitude are clarified and discussed
All-optical memory based on the injection locking bistability of a two-color laser diode
We study the injection locking bistability of a specially engineered
two-color semiconductor Fabry-Perot laser. Oscillation in the uninjected
primary mode leads to a bistability of single mode and two-color equilibria.
With pulsed modulation of the injected power we demonstrate an all-optical
memory element based on this bistability, where the uninjected primary mode is
switched with 35 dB intensity contrast. Using experimental and theoretical
analysis, we describe the associated bifurcation structure, which is not found
in single mode systems with optical injection.Comment: 5 pages, 5 figure
Towards predicting post-editing productivity
Machine translation (MT) quality is generally measured via automatic metrics, producing scores that have no meaning for translators who are required to post-edit MT output or for project managers who have to plan and budget for transla- tion projects. This paper investigates correlations between two such automatic metrics (general text matcher and translation edit rate) and post-editing productivity. For the purposes of this paper, productivity is measured via processing speed and cognitive measures of effort using eye tracking as a tool. Processing speed, average fixation time and count are found to correlate well with the scores for groups of segments. Segments with high GTM and TER scores require substantially less time and cognitive effort than medium or low-scoring segments. Future research involving score thresholds and confidence estimation is suggested
Is Mindfulness-Based Cognitive Therapy Effective for Preventing Relapse of Depression in Adults?
Objective: The objective of this selective EBM review is to determine whether or not mindfulness-based cognitive therapy is effective for preventing relapse of depression in adults.
Study Design: Review of three English-language randomized controlled trials published between 2014 and 2015.
Data Sources: Three randomized controlled trials published in peer-reviewed journals comparing mindfulness-based cognitive therapy to comparable treatment options found via PubMed.
Outcomes measured: Outcome measured was presence or absence of relapse of major depressive episodes in adults determined by the Structured Clinical Interview for DSM-IV.
Results: Kuyken et al. found that there was not a statistically significant difference in the incidence of relapse of depression in a adults between those using MBCT and those on maintenance anti-depressant therapy (p=.43 Lancet. 2015;386(9988):63-73. doi: S0140- 6736(14)62222-4 [pii]). After further analysis, the NNT for this study of 33 indicated a small treatment effect. Similarly, Shallcross et al. again found no difference between groups receiving MBCT and those participating in an active control condition (p=.91 J Consult Clin Psychol. 2015;83(5):964-975. doi: 10.1037/ccp0000050 [doi].). Again, after analysis there was a small treatment effect (NNT=-45). Finally, Williams et al. again showed no significant difference in relapse rates between groups receiving MBCT combined with TAU and those using TAU alone(p=.13 J Consult Clin Psychol. 2014;82(2):275-286. doi: 10.1037/a0035036). However, upon further analysis their treatment effects were found to be the largest of the three studies evaluated in this review (NNT=14).
Conclusion: This review showed that there is no difference between MCBT and control conditions in successful prevention of depressive episodes in adults. It was determined that MBCT is a viable treatment option for those with MDD, but it was not shown to be superior to other know treatment modalities such as antidepressant therapy or psychotherapy
Antiphase dynamics in a multimode semiconductor laser with optical injection
A detailed experimental study of antiphase dynamics in a two-mode
semiconductor laser with optical injection is presented. The device is a
specially designed Fabry-Perot laser that supports two primary modes with a THz
frequency spacing. Injection in one of the primary modes of the device leads to
a rich variety of single and two-mode dynamical scenarios, which are reproduced
with remarkable accuracy by a four dimensional rate equation model. Numerical
bifurcation analysis reveals the importance of torus bifurcations in mediating
transitions to antiphase dynamics and of saddle-node of limit cycle
bifurcations in switching of the dynamics between single and two-mode regimes.Comment: 7 pages, 9 figure
Observation of quantum interference as a function of Berry's phase in a complex Hadamard optical network
Emerging models of quantum computation driven by multi-photon quantum
interference, while not universal, may offer an exponential advantage over
classical computers for certain problems. Implementing these circuits via
geometric phase gates could mitigate requirements for error correction to
achieve fault tolerance while retaining their relative physical simplicity. We
report an experiment in which a geometric phase is embedded in an optical
network with no closed-loops, enabling quantum interference between two photons
as a function of the phase.Comment: Comments welcom
Exact zero-point energy shift in the , many modes dynamic Jahn-Teller systems at strong coupling
We find the exact semiclassical (strong coupling) zero-point energy shifts
applicable to the and dynamic Jahn-Teller
problems, for an arbitrary number of discrete vibrational modes
simultaneously coupled to one single electronic level. We also obtain an
analytical formula for the frequency of the resulting normal modes, which has
an attractive and apparently general Slater-Koster form. The limits of validity
of this approach are assessed by comparison with O'Brien's previous
effective-mode approach, and with accurate numerical diagonalizations.
Numerical values obtained for with and coupling
constants appropriate to C are used for this purpose, and are
discussed in the context of fullerene.Comment: 20 pages, 4 ps figure
The Extent and Cause of the Pre-White Dwarf Instability Strip
One of the least understood aspects of white dwarf evolution is the process
by which they are formed. We are aided, however, by the fact that many H- and
He-deficient pre-white dwarfs (PWDs) are multiperiodic g-mode pulsators.
Pulsations in PWDs provide a unique opportunity to probe their interiors, which
are otherwise inaccesible to direct observation. Until now, however, the nature
of the pulsation mechanism, the precise boundaries of the instability strip,
and the mass distribution of the PWDs were complete mysteries. These problems
must be addressed before we can apply knowledge of pulsating PWDs to improve
understanding of white dwarf formation. This paper lays the groundwork for
future theoretical investigations of these stars. In recent years, Whole Earth
Telescope observations led to determination of mass and luminosity for the
majority of the (non-central star) PWD pulsators. With these observations, we
identify the common properties and trends PWDs exhibit as a class. We find that
pulsators of low mass have higher luminosity, suggesting the range of
instability is highly mass-dependent. The observed trend of decreasing periods
with decreasing luminosity matches a decrease in the maximum (standing-wave)
g-mode period across the instability strip. We show that the red edge can be
caused by the lengthening of the driving timescale beyond the maximum
sustainable period. This result is general for ionization-based driving
mechanisms, and it explains the mass-dependence of the red edge. The observed
form of the mass-dependence provides a vital starting point for future
theoretical investigations of the driving mechanism. We also show that the blue
edge probably remains undetected because of selection effects arising from
rapid evolution.Comment: 40 pages, 6 figures, accepted by ApJ Oct 27, 199
Liver Adiposity and Metabolic Profile in Individuals with Chronic Spinal Cord Injury
Purpose. To quantify liver adiposity using magnetic resonance imaging (MRI) and to determine its association with metabolic profile in men with spinal cord injury (SCI). Materials and Methods. MRI analysis of liver adiposity by fat signal fraction (FSF) and visceral adipose tissue (VAT) was completed on twenty participants. Intravenous glucose tolerance test was conducted to measure glucose effectiveness (g) and insulin sensitivity (i ). Lipid panel, fasting glucose, glycated hemoglobin (HbA1c), and inflammatory cytokines were also analyzed. Results. Average hepatic FSF was 3.7% ± 2.1. FSF was positively related to TG, non-HDL-C, fasting glucose, HbA1c, VAT, and tumor necrosis factor alpha (TNF-). FSF was negatively related to i and testosterone. FSF was positively related to VAT ( = 0.48, = 0.032) and TNF- ( = 0.51, = 0.016) independent of age, level of injury (LOI), and time since injury (TSI). The associations between FSF and metabolic profile were independent of VAT. Conclusions. MRI noninvasively estimated hepatic adiposity in men with chronic SCI. FSF was associated with dysfunction in metabolic profile, central adiposity, and inflammation. Importantly, liver adiposity influenced metabolic profile independently of VAT. These findings highlight the significance of quantifying liver adiposity after SCI to attenuate the development of metabolic disorders
Dynamics of the Lyman alpha and C IV emitting gas in 3C 273
In this paper we study the variability properties of the Lyman alpha and C IV
emission lines in 3C273 using archival IUE observations. Our data show for the
first time the existence of variability on time scales of several years. We
study the spatial distribution and the velocity field of the emitting gas by
performing detailed analyses on the line variability using correlations, 1D and
2D response functions, and principal component analysis. In both lines we find
evidence for two components, one which has the dynamic properties of gas in
Keplerian motion around a black hole with a mass of the order of 10^9 Mo, and
one which is characterized by high, blue-shifted velocities at large lag. There
is no indication of the presence of optically thick emission medium neither in
the Lya, nor in the Civ response functions. The component characterized by
blue-shifted velocities, which is comparatively much stronger in Civ than in
Lya, is more or less compatible with being the result of gas falling towards
the central black hole with free-fall acceleration. We propose however that the
line emission at high, blue-shifted velocities is better explained in terms of
entrainment of gas clouds by the jet. This gas is therefore probably
collisionally excited as a result of heating due to the intense infrared
radiation from the jet, which would explain the strength of this component in
Civ relative to Lya. This phenomenon might be a signature of disk-jet
interaction.Comment: 16 pages, 10 figures. Accepted for publication in ApJ. Uses aaste
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