3,013 research outputs found
Autoionizing Polaritons in Attosecond Atomic Ionization
Light-induced states are commonly observed in the photoionization spectra of
laser-dressed atoms. The properties of autoionizing polaritons, entangled
states of light and Auger resonances, however, are largely unexplored. We
employ attosecond transient-absorption spectroscopy to study the evolution of
autoionizing states in argon, dressed by a tunable femtosecond laser pulse. The
avoided crossings between the and several light-induced states
indicates the formation of polariton multiplets. We measure a controllable
stabilization of the polaritons against ionization, in excellent agreement with
\emph{ab initio} theory. Using an extension of the Jaynes-Cummings model to
autoionizing states, we show that this stabilization is due to the destructive
interference between the Auger decay and the radiative ionization of the
polaritonic components. These results give new insights into the optical
control of electronic structure in the continuum, and unlock the door to
applications of autoionizing polaritons in poly-electronic systems.Comment: 5 pages, 3 figure
Leader development for adolescent girls:State of the field and a framework for moving forward
No evidence that autistic traits predict programming learning outcomes
With the increased importance of computer programming in society, researchers have been searching for ways to predict which students are most likely to succeed, as well as those who may have difficulty when beginning to learn to program. It has been suggested that autistic traits relate to increased interest and aptitude for abstract science, and that people with higher numbers of autistic traits have a stronger tendency to ‘systemize’, which can be advantageous for studying natural and manmade systems. This could also mean that higher autistic traits are associated with greater programming abilities. In this study, we therefore investigated whether autistic traits, measured with the Autism Spectrum Quotient (AQ), predicted course grades and performance on an independent programming test at the end of an introductory undergraduate programming course. We also examined the relationship between AQ scores and five cognitive skills that were measured at the start of the programming course (logical reasoning, pattern recognition, algebra, vocabulary learning, grammar learning). We found that the participants scored higher on autistic traits than the general population. However, overall autistic traits did not predict programming skill at the end of the course. Similarly, no individual subscale of the AQ predicted programming skills, nor were there any correlations between cognitive skills and autistic traits. Therefore, there is no evidence to support autistic traits being reliably related to programming skill acquisition
The Role of the Results of Functional Tests and Psychological Factors on Prediction of Injuries in Adolescent Female Football Players
Football is a popular sport among adolescent females. Given the rate of injuries in female footballers, identifying factors that can predict injuries are important. These injuries are often caused by complex reasons. The aim of this study was to investigate if the combination of demographic (age, number of training and match play hours/week), psychosocial (perceived stress, adaptive coping strategies) and physiological factors (functional performance) can predict a traumatic injury in adolescent female footballers. A cohort consisting of 419 female football players aged 13–16 years was established. Baseline questionnaires covered potential risk factors for sport injuries, and measurements included football-related functional performance tests. Data were collected prospectively with a weekly online questionnaire for 52 weeks covering, e.g., injuries, training, and match play hours/week. A total of 62% of the players reported at least one traumatic injury during the 52 weeks. The coping strategy “positive reframing” had the strongest association with the risk of traumatic injuries. The combination of more frequent use of the coping strategy, positive reframing, and high levels of physical performance capacity may prevent a traumatic injury in adolescent female footballers. Coaches are encouraged to adopt both physiological and psychological factors when preventing injuries in young female footballers.publishedVersio
A Jaynes-Cummings-Fano Model for Autoionizing Polaritons
Intense laser pulses can couple resonances in the continuum, giving rise to a
split pair of autoionizing polaritons whose lifetime can be extended as a
result of interference between radiative and Auger decay channels. We present
an extension of the Jaynes-Cummings model to autoionizing states which
quantitatively reproduces this phenomenology and allows us to study how the
dressing laser parameters can be tuned to control the ionization rate of the
polariton multiplet. We illustrate the potential of this model to estimate the
splitting and widths of the polaritonic features in the attosecond
transient-absorption spectrum of the argon atom in the energy region close to
the autoionizing states and compare the results with ab initio
simulations of the spectrum in realistic experimental conditions.Comment: 15 pages, 13 figure
SUSY Gauge Dynamics and Singularities of 4d N=1 String Vacua
Many N=1 heterotic string compactifications exhibit physically mysterious
singularities at codimension one in the moduli space of vacua. At these
singularities, Yukawa couplings of charged fields develop poles as a function
of the moduli. We explain these conformal field theory singularities, in a
class of examples, as arising from non-perturbative gauge dynamics of
non-perturbative gauge bosons (whose gauge coupling is the sigma model
coupling) in the string theory.Comment: 17 pages, harvmac bi
Highly turbulent gas on GMC-scales in NGC 3256, the nearest luminous infrared galaxy
We present the highest resolution CO (2-1) observations obtained to date
(0.25") of NGC 3256 and use them to determine the detailed properties of the
molecular interstellar medium in the central 6 kpc of this merger.
Distributions of physical quantities are reported from pixel-by-pixel
measurements at 55 and 120 pc scales and compared to disc galaxies observed by
PHANGS-ALMA. Mass surface densities range from 8 to 5500 M pc
and velocity dispersions from 10 to 200 km s. Peak brightness
temperatures as large as 37 K are measured, indicating the gas in NGC 3256 may
be hotter than all regions in nearby disc galaxies measured by PHANGS-ALMA.
Brightness temperatures even surpass those in the overlap region of NGC 4038/9
at the same scales. The majority of the gas appears unbound with median virial
parameters of 7 to 19, although external pressure may bind some of the gas.
High internal turbulent pressures of 10 to 10 K cm are
found. Given the lack of significant trends in surface density, brightness
temperature, and velocity dispersion with physical scale we argue the molecular
gas is made up of a smooth medium down to 55 pc scales, unlike the more
structured medium found in the PHANGS-ALMA disc galaxies.Comment: accepted to MNRAS, 21 pages, 8 figure
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