1,997 research outputs found
Energy and directional signatures for plane quantized gravity waves
Solutions are constructed to the quantum constraints for planar gravity
(fields dependent on z and t only) in the Ashtekar complex connection
formalism. A number of operators are constructed and applied to the solutions.
These include the familiar ADM energy and area operators, as well as new
operators sensitive to directionality (z+ct vs. z-ct dependence). The
directionality operators are quantum analogs of the classical constraints
proposed for unidirectional plane waves by Bondi, Pirani, and Robinson (BPR).
It is argued that the quantum BPR constraints will predict unidirectionality
reliably only for solutions which are semiclassical in a certain sense. The ADM
energy and area operators are likely to have imaginary eigenvalues, unless one
either shifts to a real connection, or allows the connection to occur other
than in a holonomy. In classical theory, the area can evolve to zero. A quantum
mechanical mechanism is proposed which would prevent this collapse.Comment: 54 pages; LaTe
Projective Invariance and One-Loop Effective Action in Affine-Metric Gravity Interacting with Scalar Field
We investigate the influence of the projective invariance on the
renormalization properties of the theory. One-loop counterterms are calculated
in the most general case of interaction of gravity with scalar field.Comment: 10 pages, LATE
Test particles behavior in the framework of a lagrangian geometric theory with propagating torsion
Working in the lagrangian framework, we develop a geometric theory in vacuum
with propagating torsion; the antisymmetric and trace parts of the torsion
tensor, considered as derived from local potential fields, are taken and, using
the minimal action principle, their field equations are calculated. Actually
these will show themselves to be just equations for propagating waves giving
torsion a behavior similar to that of metric which, as known, propagates
through gravitational waves. Then we establish a principle of minimal
substitution to derive test particles equation of motion, obtaining, as result,
that they move along autoparallels. We then calculate the analogous of the
geodesic deviation for these trajectories and analyze their behavior in the
nonrelativistic limit, showing that the torsion trace potential has a
phenomenology which is indistinguishable from that of the gravitational
newtonian field; in this way we also give a reason for why there have never
been evidence for it.Comment: 12 pages, no figures, to appear on Int. Journ. Mod. Phys.
Selection of the intrinsic polarization properties of animal optical materials creates enhanced structural reflectivity and camouflage
Using Modern Technologies to Capture and Share Indigenous Astronomical Knowledge
Indigenous Knowledge is important for Indigenous communities across the globe
and for the advancement of our general scientific knowledge. In particular,
Indigenous astronomical knowledge integrates many aspects of Indigenous
Knowledge, including seasonal calendars, navigation, food economics, law,
ceremony, and social structure. We aim to develop innovative ways of capturing,
managing, and disseminating Indigenous astronomical knowledge for Indigenous
communities and the general public for the future. Capturing, managing, and
disseminating this knowledge in the digital environment poses a number of
challenges, which we aim to address using a collaborative project involving
experts in the higher education, library, and industry sectors. Using
Microsoft's WorldWide Telescope and Rich Interactive Narratives technologies,
we propose to develop software, media design, and archival management solutions
to allow Indigenous communities to share their astronomical knowledge with the
world on their terms and in a culturally sensitive manner.Comment: Australian Academic & Research Libraries, Vol. 45(2), pp. 101-11
Quantization of pure gravitational plane waves
Pure gravitational plane waves are considered as a special case of spacetimes
with two commuting spacelike Killing vector fields. Starting with a
midisuperspace that describes this kind of spacetimes, we introduce
gauge-fixing and symmetry conditions that remove all non-physical degrees of
freedom and ensure that the classical solutions are plane waves. In this way,
we arrive at a reduced model with no constraints and whose only degrees of
freedom are given by two fields. In a suitable coordinate system, the reduced
Hamiltonian that generates the time evolution of this model turns out to
vanish, so that all relevant information is contained in the symplectic
structure. We calculate this symplectic structure and particularize our
discussion to the case of linearly polarized plane waves. The reduced phase
space can then be described by an infinite set of annihilation and creation
like variables. We finally quantize the linearly polarized model by introducing
a Fock representation for these variables.Comment: 11 pages, Revtex, no figure
Outcome following multiple subpial transection in Landau-Kleffner syndrome and related regression
OBJECTIVE: To determine whether multiple subpial transection in the posterior temporal lobe has an impact on long-term outcome in children who have drug-resistant Landau-Kleffner syndrome (LKS) or other "electrical status epilepticus during sleep" (ESES)-related regression. Given the wide variability in outcomes reported in the literature, a secondary aim was to explore predictors of outcome. METHODS: The current study includes a surgery group (n = 14) comprising patients who underwent multiple subpial transection of the posterior temporal lobe and a nonsurgery comparison group (n = 21) comprising patients who underwent presurgical investigations for the procedure, but who did not undergo surgery. Outcomes were assessed utilizing clinical note review as well as direct assessment and questionnaires. RESULTS: The distribution of nonclassical cases was comparable between groups. There were some differences between the surgery and nonsurgery groups at presurgical investigation including laterality of discharges, level of language impairment, and age; therefore, follow-up analyses focused on change over time and predictors of outcome. There were no statistically significant differences between the groups in language, nonverbal ability, adaptive behavior, or quality of life at follow-up. There was no difference in the proportion of patients showing improvement or deterioration in language category over time for either group. Continuing seizures and an earlier age of onset were most predictive of poorer quality of life at long-term follow-up (F2,23  = 26.2, p = <0.001, R(2)  = 0.714). SIGNIFICANCE: Both surgery and nonsurgery groups had similar proportions of classic LKS and ESES-related regression. Because no significant differences were found in the changes observed from baseline to follow-up between the two groups, it is argued that there is insufficient evidence to suggest that multiple subpial transection provides additional benefits over and above the mixed recovery often seen in LKS and related regressive epilepsies
Seventy years of sex education in Health Education Journal: a critical review
This paper examines key debates and perspectives on sex education in Health Education Journal (HEJ), from the date of the journal’s first publication in March 1943 to the present day. Matters relating to sexuality and sexual health are revealed to be integral to HEJ’s history. First published as Health and Empire (1921 – 1942), a key purpose of the journal since its inception has been to share information on venereal disease and its prevention within the UK and across the former British Empire. From 1943 to the present day, discussions on sex education in the newly-christened HEJ both reflect and respond to evolving socio-cultural attitudes towards sexuality in the UK. Changing definitions of sex education across the decades are examined, from the prevention of venereal disease and moral decline in war-time Britain in the 1940s, to a range of responses to sexual liberation in the 1960s and 1970s; from a focus on preventing sexually-transmitted infections, teenage pregnancy and HIV in the 1980s, to the provision of sexual health services alongside sex education in the 2000s. Over the past 70 years, a shift from prevention of pre-marital sexual activity to the management of its outcomes is apparent; however, while these changes over time are notable, perhaps the most striking findings of this review are the continuities in arguments for and against the discussion of sexual issues. After more than 70 years of debate, it would seem that there is little consensus concerning motivations for and the content of sex education
Pain associated with pressure injury: A qualitative study of community-based, home-dwelling individuals
© 2017 John Wiley & Sons Ltd. Aims: The aim of this study was to provide deep insights into the pain associated with pressure injuries in home-dwelling individuals using narrative accounts. Background: Pressure injuries or pressure ulcers are burdensome and costly. Prevalence data, surveys and systematic reviews demonstrate that pain associated with pressure injury is widespread, but voices of home-dwelling patients have remained largely unheard. Design: Concurrent mixed methods case study of a UK community of approximately 50,000 adults. Methods: Qualitative interviews, conducted in 2016, of 12 home-dwelling adult participants with a current pressure injury (n = 10), or a recently healed pressure injury (n = 2). Findings: Pain had an adverse impact on activities of daily living, mobility and sleep. Participants described days that were clouded in pain; a pain they felt was poorly understood and often out of control. Thematic content analysis revealed two major themes; these are: Poorly controlled pain: “I just want the pain to go away”; and, Uncertainty for the future: “it almost seems insurmountable.”. Conclusion: Findings of our study support the need to develop an appropriate assessment tool for pressure injury patients in the community to enable healthcare professionals and patients to recognize and manage pressure injury-related pain effectively
Health service provision and the use of pressure-redistributing devices: mixed methods study of community dwelling individuals with pressure injuries
© 2017 Informa UK Limited, trading as Taylor & Francis Group. Background: Health care within the home setting is a vital and growing component of pressure injury (PI) prevention and management. Objectives: To describe the use of health services and pressure-redistributing devices in community dwelling patients with PI’s. Design: Mixed-methods collective case study of a defined, diverse geographic postcode area in the United Kingdom. Methods: Quantitative retrospective analysis of electronic and paper medical records of adult PI patients from 2015 district nursing reports. Qualitative semi-structured interviews of community dwelling adult patients receiving, or received, treatment for PI in 2016. Results: Mandatory reports (n = 103) revealed that 90 patients were supplied with a variety of pressure-redistributing devices but only one-third of patients used the equipment as recommended. Qualitative interviews (n = 12), reported to COREQ guidelines, revealed that patients felt reliant on community health services, and were concerned about the consistency of their care. Conclusions: Authentic patient involvement is required to provide care and interventions that are acceptable to PI patients and can be incorporated into self-care strategies and effectively monitored
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