30,317 research outputs found
Contrast Interferometry Using Bose-Einstein Condensates to Measure h/m and the Fine Structure Constant
The kinetic energy of an atom recoiling due to absorption of a photon was
measured as a frequency using an interferometric technique called ``contrast
interferometry''. Optical standing wave pulses were used as atom-optical
elements to create a symmetric three-path interferometer with a Bose-Einstein
condensate. The recoil phase accumulated in different paths was measured using
a single-shot detection technique. The scheme allows for additional photon
recoils within the interferometer and its symmetry suppresses several random
and systematic errors including those from vibrations and ac Stark shifts. We
have measured the photon recoil frequency of sodium to ppm precision, using
a simple realization of this scheme. Plausible extensions should yield a
sufficient precision to bring within reach a ppb-level determination of
and the fine structure constant
Harnessing shared identities to mobilise resilient responses to the COVID-19 pandemic
Shared social identifications (family, community, nation, humanity) predict normative actions and psychological well-being, and can be invoked discursively by leaders to mobilise their followers. We illustrate the potential for harnessing shared identities to mobilise resilient public responses against COVID-19. Study 1 explored which patterns of social identification predicted protective behaviours (personal hygiene, physical distancing), prosocial actions (helping proximal and distal others), and psychological well-being (mental well-being, depressive symptoms, anxiety), among 560 UK adults surveyed during lockdown. Study 2 contrasted Prime Minister Ardernâs use of identity-based rhetoric to mobilise New Zealanders, with Prime Minister Johnsonâs use of individualistic appeals to the UK public. Our findings suggest how political leaders might beneficially use social identities in communications about extreme events
Evaluating the implementation of a âChild Firstâ approach within Plymouthâs Youth Justice multi-agency diversion scheme.
The Triple Pulsar System PSR B1620-26 in M4
The millisecond pulsar PSR B1620-26, in the globular cluster M4, has a white
dwarf companion in a half-year orbit. Anomalously large variations in the
pulsar's apparent spin-down rate have suggested the presence of a second
companion in a much wider orbit. Using timing observations made on more than
seven hundred days spanning eleven years, we confirm this anomalous timing
behavior. We explicitly demonstrate, for the first time, that a timing model
consisting of the sum of two non-interacting Keplerian orbits can account for
the observed signal. Both circular and elliptical orbits are allowed, although
highly eccentric orbits require improbable orbital geometries.
The motion of the pulsar in the inner orbit is very nearly a Keplerian
ellipse, but the tidal effects of the outer companion cause variations in the
orbital elements. We have measured the change in the projected semi-major axis
of the orbit, which is dominated by precession-driven changes in the orbital
inclination. This measurement, along with limits on the rate of change of other
orbital elements, can be used to significantly restrict the properties of the
outer orbit. We find that the second companion most likely has a mass m~0.01
Msun --- it is almost certainly below the hydrogen burning limit (m<0.036 Msun,
95% confidence) --- and has a current distance from the binary of ~35 AU and
orbital period of order one hundred years. Circular (and near-circular) orbits
are allowed only if the pulsar magnetic field is ~3x10^9 G, an order of
magnitude higher than a typical millisecond pulsar field strength. In this
case, the companion has mass m~1.2x10^-3 Msun and orbital period ~62 years.Comment: 12 pages, 6 figures, 3 tables. Very minor clarifications and
rewording. Accepted for publication in the Astrophys.
Sexual Wellness and Rare Disease Considerations: A Behavioral Case Conceptualization and Approach to Counseling Treatment
Sexual wellness is infrequently addressed with individuals with a rare disease. Counselors must be competent in working with sexual wellness issues, especially those related to medical conditions, since clients may not share those concerns with healthcare providers. This article presents a case scenario involving a client living with a rare disease called Hereditary Angioedema, the symptoms of which present challenges to her intimate and sexual relationship with her partner due to unpredictable and painful swelling. A behavioral theoretical lens is used to conceptualize the case scenario and inform treatment. Implications for counselor competency, interdisciplinary collaboration, and client empowerment toward advocacy are discussed
Measurement of Relativistic Orbital Decay in the PSR B1534+12 Binary System
We have made timing observations of binary pulsar PSR B1534+12 with radio
telescopes at Arecibo, Green Bank, and Jodrell Bank. By combining our new
observations with data collected up to seven years earlier, we obtain a
significantly improved solution for the astrometric, spin, and orbital
parameters of the system. For the first time in any binary pulsar system, no
fewer than five relativistic or "post-Keplerian" orbital parameters are
measurable with useful accuracies in a theory-independent way. We find the
orbital period of the system to be decreasing at a rate close to that expected
from gravitational radiation damping, according to general relativity, although
the precision of this test is limited to about 15% by the otherwise poorly
known distance to the pulsar. The remaining post-Keplerian parameters are all
consistent with one another and all but one of them have fractional accuracies
better than 1%. By assuming that general relativity is the correct theory of
gravity, at least to the accuracy demanded by this experiment, we find the
masses of the pulsar and companion star each to be 1.339+-0.003 Msun and the
system's distance to be d = 1.1+-0.2 kpc, marginally larger than the d ~ 0.7
kpc estimated from the dispersion measure. The increased distance reduces
estimates of the projected rate of coalescence of double neutron-star systems
in the universe, a quantity of considerable interest for experiments with
terrestrial gravitational wave detectors such as LIGO.Comment: 17 pages, 4 figures, submitted to the Ap
Correlation functions of small-scale fluctuations of the interplanetary magnetic field
The Interplanetary Magnetic Field shows complex spatial and temporal
variations. Single spacecraft measurements reveal only a one dimensional
section of this rich four dimensional phenomenon. Multi-point measurements of
the four Cluster spacecraft provide a unique tool to study the spatiotemporal
structure of the field. Using Cluster data we determined three dimensional
correlation functions of the fluctuations. By means of the correlation function
one can describe and measure field variations. Our results can be used to
verify theoretical predictions, to understand the formation and nature of solar
wind turbulence. We found that the correlation length varies over almost six
orders of magnitude. The IMF turbulence shows significant anisotropy with two
distinct populations. In certain time intervals the ratio of the three axes of
the correlation ellipse is 1/2.2/6 while in the remaining time we found
extremely high correlation along one axis. We found favoured directions in the
orientation of the correlation ellipsoids.Comment: accepted to Solar Physics on June 14, 2010. 10 pages, 8 figure
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