24,296 research outputs found
Amplitude squeezed light from a laser
Intensity squeezed light was successfully generated using semiconductor lasers with sub-Poissonian pumping. Control of the pumping statistics is crucial and is achieved by a large series resistor which regulates the pump current; its sub-Poissonian statistics are then transferred to the laser output. The sub-Poissonian pumping of other laser systems is not so simple, however, and their potential as squeezed states sources is apparently diminished. We consider a conventional laser incoherently pumped well above threshold, and allow for pump depletion of the ground state. In this regime, sub-Poissonian photon statistics and squeezed amplitude fluctuations are produced
Prevalence of overall and central obesity among adolescent girls in Port Harcourt: a comparison of different methods
There is no universally accepted criterion for classification of overall weight status and central obesity in adolescents. Several criteria have been used which include that recommended by Centre for Disease control, World Health Organization and the International Obesity Task Force.Aim: The study compared various methods for determination of overall obesity in adolescents using the BMI percentiles recommended by the Centre for Disease Control (CDC), the International Obesity Task Force (IOTF) and the World Health Organization (WHO) BMI Z score and determination of central obesity using the waist circumference (WC), Waist Hip Ratio (WHR) and Waist Height Ratio (WHtR).Methods: The study subjects consisted of 1320 girls aged 10-19 years from randomly selected girl’s high school. Weight status to determine overall obesity was determined according to the CDC, IOTF and WHO criteria and central obesity determined using the WC, WHR, and WHtR. Comparison of methods was done and analysed.Results: Prevalence of overall and central obesity varied with different methods. The prevalence of overall obesity was 106(8.02%), 69(5.22%) and 39(2.75%) using the CDC, WHO and IOTF criteria respectively. Prevalence of central obesity was 1.5%, 16.26%, 47.81% using the WC, WHtR, and WHR respectively. The agreement between criteria of WHO Z score and BMI Percentile was highest for overall obesity. (K=0.81). There was a statistically significant association between overall weight status and central obesity using the different criteria of determination of central obesity.Conclusion: Prevalence of overall obesity and central obesity varied based on the methods used. The highest level of agreement for overall obesity determination was obtained between WHO Z score and BMI percentile compared to WHO Z score and IOTF criteria. Prevalence of central obesity increased significantly with overall obesity in study population.Key words: adolescents, Girls, overall and central obesit
Structural model optimization using statistical evaluation
The results of research in applying statistical methods to the problem of structural dynamic system identification are presented. The study is in three parts: a review of previous approaches by other researchers, a development of various linear estimators which might find application, and the design and development of a computer program which uses a Bayesian estimator. The method is tried on two models and is successful where the predicted stiffness matrix is a proper model, e.g., a bending beam is represented by a bending model. Difficulties are encountered when the model concept varies. There is also evidence that nonlinearity must be handled properly to speed the convergence
Study protocol: Delayed intervention randomised controlled trial within the Medical Research Council (MRC) Framework to assess the effectiveness of a new palliative care service
Background: Palliative care has been proposed to help meet the needs of patients who suffer
progressive non-cancer conditions but there have been few evaluations of service development
initiatives. We report here a novel protocol for the evaluation of a new palliative care service in
this context.
Methods/Design: Using the MRC Framework for the Evaluation of Complex Interventions we
modelled a new palliative care and neurology service for patients severely affected by Multiple
Sclerosis (MS). We conducted qualitative interviews with patients, families and staff, plus a
literature review to model and pilot the service. Then we designed a delayed intervention
randomised controlled trial to test its effectiveness as part of phase II of the MRC framework.
Inclusion criteria for the trial were patients identified by referring clinicians as having unresolved
symptoms or psychological concerns. Referrers were advised to use a score of greater than 8 on
the Expanded Disability Scale was a benchmark. Consenting patients newly referred to the new
service were randomised to either receive the palliative care service immediately (fast-track) or
after a 12-week wait (standard best practice). Face to face interviews were conducted at baseline
(before intervention), and at 4–6, 10–12 (before intervention for the standard-practice group), 16–
18 and 22–24 weeks with patients and their carers using standard questionnaires to assess
symptoms, palliative care outcomes, function, service use and open comments. Ethics committee
approval was granted separately for the qualitative phase and then for the trial.
Discussion: We publish the protocol trial here, to allow methods to be reviewed in advance of
publication of the results. The MRC Framework for the Evaluation of Complex Interventions was
helpful in both the design of the service, methods for evaluation in convincing staff and the ethics
committee to accept the trial. The research will provide valuable information on the effects of
palliative care among non-cancer patients and a method to evaluate palliative care in this context
A synopsis of recent North American microtine rodents
http://deepblue.lib.umich.edu/bitstream/2027.42/56364/1/MP120.pd
The multiple junction edge illuminated solar cell
The multiple junction edge illuminated solar cell was devised for high voltage low current applications. Devices to be flight tested in early 1974 with 96 series connected PNN+ junctions in a 2 cm X 2.3 cm size deliver 36 volts at 1 milliampere. Test data of M-J cells fabricated with resistivities of 10, 50, 100, 200, 450, and 1000 ohm cm silicon are presented and problem areas are discussed. An additional potential application of the M-J cell lies in ultilization of its high intensity performance that has been demonstrated at levels in excess of 100 AMO suns
Experimental autoimmune encephalomyelitis in the common marmoset: a translationally relevant model for the cause and course of multiple sclerosis
Aging Western societies are facing an increasing prevalence of chronic
autoimmune-mediated inflammatory disorders (AIMIDs) for which treatments that are safe and effective are scarce. One of the
main reasons for this situation is the lack of animal models, which accurately replicate
clinical and pathological aspects of the human diseases. One important AIMID is the
neuroinflammatory disease multiple sclerosis (MS), for which the mouse experimental
autoimmune encephalomyelitis (EAE) model has been frequently used in preclinical
research. Despite some successes, there is a long list of experimental treatments that
have failed to reproduce promising effects observed in murine EAE models when they were
tested in the clinic. This frustrating situation indicates a wide validity gap between
mouse EAE and MS. This monography describes the development of an EAE model in nonhuman
primates, which may help to bridge the gap.</p
The monopole mass in the three-dimensional Georgi-Glashow model
We study the three-dimensional Georgi-Glashow model to demonstrate how
magnetic monopoles can be studied fully non-perturbatively in lattice Monte
Carlo simulations, without any assumptions about the smoothness of the field
configurations. We examine the apparent contradiction between the conjectured
analytic connection of the `broken' and `symmetric' phases, and the
interpretation of the mass (i.e., the free energy) of the fully quantised 't
Hooft-Polyakov monopole as an order parameter to distinguish the phases. We use
Monte Carlo simulations to measure the monopole free energy and its first
derivative with respect to the scalar mass. On small volumes we compare this to
semi-classical predictions for the monopole. On large volumes we show that the
free energy is screened to zero, signalling the formation of a confining
monopole condensate. This screening does not allow the monopole mass to be
interpreted as an order parameter, resolving the paradox.Comment: 12 pages, 7 figures, uses revtex. Minor changes made to the text to
match with the published version at
http://link.aps.org/abstract/PRD/v65/e12500
Casimir scaling of domain wall tensions in the deconfined phase of D=3+1 SU(N) gauge theories
We perform lattice calculations of the spatial 't Hooft k-string tensions in
the deconfined phase of SU(N) gauge theories for N=2,3,4,6. These equal (up to
a factor of T) the surface tensions of the domain walls between the
corresponding (Euclidean) deconfined phases. For T much larger than Tc our
results match on to the known perturbative result, which exhibits Casimir
Scaling, being proportional to k(N-k). At lower T the coupling becomes stronger
and, not surprisingly, our calculations show large deviations from the
perturbative T-dependence. Despite this we find that the behaviour proportional
to k(N-k) persists very accurately down to temperatures very close to Tc. Thus
the Casimir Scaling of the 't Hooft tension appears to be a `universal' feature
that is more general than its appearance in the low order high-T perturbative
calculation. We observe the `wetting' of these k-walls at T around Tc and the
(almost inevitable) `perfect wetting' of the k=N/2 domain wall. Our
calculations show that as T tends to Tc the magnitude of the spatial `t Hooft
string tension decreases rapidly. This suggests the existence of a (would-be)
't Hooft string condensation transition at some temperature which is close to
but below Tc. We speculate on the `dual' relationship between this and the
(would-be) confining string condensation at the Hagedorn temperature that is
close to but above Tc.Comment: 40 pages, 14 figure
High power coupled CO2 waveguide laser array
A hollow-bore ridge waveguide technique for phase locking arrays of coupled CO2 rf excited waveguide lasers was demonstrated. Stable phase-locked operation of two- and three-channel arrays has been demonstrated at the 50 W output level. Preliminary experiments with a five-element array generated an output power of 95 W but phase-locked operation was not conclusively demonstrated
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