389 research outputs found
An accelerator mode based technique for studying quantum chaos
We experimentally demonstrate a method for selecting small regions of phase
space for kicked rotor quantum chaos experiments with cold atoms. Our technique
uses quantum accelerator modes to selectively accelerate atomic wavepackets
with localized spatial and momentum distributions. The potential used to create
the accelerator mode and subsequently realize the kicked rotor system is formed
by a set of off-resonant standing wave light pulses. We also propose a method
for testing whether a selected region of phase space exhibits chaotic or
regular behavior using a Ramsey type separated field experiment.Comment: 5 pages, 3 figures, some modest revisions to previous version (esp.
to the figures) to aid clarity; accepted for publication in Physical Review A
(due out on January 1st 2003
Comorbidity and repeat admission to hospital for adverse drug reactions in older adults: retrospective cohort study
Objectives To identify factors that predict repeat admission to hospital for adverse drug reactions (ADRs) in older adults
Coherent Manipulation of Quantum Delta-kicked Dynamics: Faster-than-classical Anomalous Diffusion
Large transporting regular islands are found in the classical phase space of
a modified kicked rotor system in which the kicking potential is reversed after
every two kicks. The corresponding quantum system, for a variety of system
parameters and over long time scales, is shown to display energy absorption
that is significantly faster than that associated with the underlying classical
anomalous diffusion. The results are of interest to both areas of quantum chaos
and quantum control.Comment: 6 pages, 4 figures, to appear in Physical Review
Control of Dynamical Localization
Control over the quantum dynamics of chaotic kicked rotor systems is
demonstrated. Specifically, control over a number of quantum coherent phenomena
is achieved by a simple modification of the kicking field. These include the
enhancement of the dynamical localization length, the introduction of classical
anomalous diffusion assisted control for systems far from the semiclassical
regime, and the observation of a variety of strongly nonexponential lineshapes
for dynamical localization. The results provide excellent examples of
controlled quantum dynamics in a system that is classically chaotic and offer
new opportunities to explore quantum fluctuations and correlations in quantum
chaos.Comment: 9 pages, 7 figures, to appear in Physical Review
Chimpanzees do not take into account what others can hear in a competitive situation
Chimpanzees (Pan troglodytes) know what others can and cannot see in a competitive situation. Does this reflect a general understanding the perceptions of others? In a study by Hare et al. (2000) pairs of chimpanzees competed over two pieces of food. Subordinate individuals preferred to approach food that was behind a barrier that the dominant could not see, suggesting that chimpanzees can take the visual perspective of others. We extended this paradigm to the auditory modality to investigate whether chimpanzees are sensitive to whether a competitor can hear food rewards being hidden. Results suggested that the chimpanzees did not take what the competitor had heard into account, despite being able to locate the hiding place themselves by the noise
Emittance preservation in a plasma-wakefield accelerator
Radio-frequency particle accelerators are engines of discovery, powering high-energy physics and photon science, but are also large and expensive due to their limited accelerating fields. Plasma-wakefield accelerators (PWFAs) provide orders-of-magnitude stronger fields in the charge-density wave behind a particle bunch travelling in a plasma, promising particle accelerators of greatly reduced size and cost. However, PWFAs can easily degrade the beam quality of the bunches they accelerate. Emittance, which determines how tightly beams can be focused, is a critical beam quality in for instance colliders and free-electron lasers, but is particularly prone to degradation. We demonstrate, for the first time, emittance preservation in a high-gradient and high-efficiency PWFA while simultaneously preserving charge and energy spread. This establishes that PWFAs can accelerate without degradation—an essential step toward energy boosters in photon science and multistage facilities for compact high-energy particle colliders
Mental Health of Parents and Life Satisfaction of Children: A Within-Family Analysis of Intergenerational Transmission of Well-Being
This paper addresses the extent to which there is an intergenerational transmission of mental health and subjective well-being within families. Specifically it asks whether parents’ own mental distress influences their child’s life satisfaction, and vice versa. Whilst the evidence on daily contagion of stress and strain between members of the same family is substantial, the evidence on the transmission between parental distress and children’s well-being over a longer period of time is sparse. We tested this idea by examining the within-family transmission of mental distress from parent to child’s life satisfaction, and vice versa, using rich longitudinal data on 1,175 British youths. Results show that parental distress at year t-1 is an important determinant of child’s life satisfaction in the current year. This is true for boys and girls, although boys do not appear to be affected by maternal distress levels. The results also indicated that the child’s own life satisfaction is related with their father’s distress levels in the following year, regardless of the gender of the child. Finally, we examined whether the underlying transmission correlation is due to shared social environment, empathic reactions, or transmission via parent-child interaction
An updated measurement of the Hubble constant from near-infrared observations of Type Ia supernovae
We present a measurement of the Hubble constant () using type Ia
supernova (SNe Ia) in the near-infrared (NIR) from the recently updated sample
of SNe Ia in nearby galaxies with distances measured via Cepheid
period-luminosity relations by the SHOES project. We collect public
near-infrared photometry of up to 19 calibrator SNe Ia and further 57 SNe Ia in
the Hubble flow (), and directly measure their peak magnitudes in the
and band by Gaussian processes and spline interpolation. Calibrator
peak magnitudes together with Cepheid-based distances are used to estimate the
average absolute magnitude in each band, while Hubble-flow SNe are used to
constrain the zero-point intercept of the magnitude-redshift relation. Our
baseline result of is (stat) (syst) km s
Mpc in the band and (stat) (syst) km s
Mpc in the band, where the systematic uncertainties include the
standard deviation of up to 21 variations of the analysis, the 0.7\% distance
scale systematic from SHOES Cepheid anchors, a photometric zeropoint
systematic, and a cosmic variance systematic. Our final measurement represents
a measurement with a precision of 2.8\% in both bands. The variant with the
largest change in is when limiting the sample to SNe from CSP and CfA
programmes, noteworthy because these are the best calibrated, yielding
km s Mpc in both bands. We demonstrate stretch and
reddening corrections are still useful in the NIR to standardize SN Ia NIR peak
magnitudes. Based on our results, in order to improve the precision of the
measurement with SNe Ia in the NIR in the future, we would need to
increase the number of calibrator SNe Ia, be able to extend the
Hubble-Lema\^itre diagram to higher-z, and include standardization procedures
to help reducing the NIR intrinsic scatter.Comment: 15 pages, 8 figures. Accepted in A&
Menstruation as a Weapon of War – The Politics of the Bleeding Body for Women on Political Protest at Armagh Prison Northern Ireland.
This article draws on the voices of women political prisoners who were detained at Armagh Prison during the period of the Troubles or the Conflict in Northern Ireland. It focuses on women who undertook an extraordinary form of protest against the prison authorities during the 1980s, known as the No Wash Protest. As the prisoners were prevented from leaving their cells by prison officer either to wash or to use the toilet, the women, living in the midst of their own dirt and body waste, added menstrual blood as a form of protest
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