2,056 research outputs found
Partition Function for (2+1)-Dimensional Einstein Gravity
Taking (2+1)-dimensional pure Einstein gravity for arbitrary genus as a
model, we investigate the relation between the partition function formally
defined on the entire phase space and the one written in terms of the reduced
phase space. In particular the case of is analyzed in detail.
By a suitable gauge-fixing, the partition function basically reduces to
the partition function defined for the reduced system, whose dynamical
variables are . [The 's are the Teichm\"uller
parameters, and the 's are their conjugate momenta.]
As for the case of , we find out that is also related with another
reduced form, whose dynamical variables are and .
[Here is a conjugate momentum to 2-volume .] A nontrivial factor
appears in the measure in terms of this type of reduced form. The factor turns
out to be a Faddeev-Popov determinant coming from the time-reparameterization
invariance inherent in this type of formulation. Thus the relation between two
reduced forms becomes transparent even in the context of quantum theory.
Furthermore for , a factor coming from the zero-modes of a differential
operator can appear in the path-integral measure in the reduced
representation of . It depends on the path-integral domain for the shift
vector in : If it is defined to include , the nontrivial factor
does not appear. On the other hand, if the integral domain is defined to
exclude , the factor appears in the measure. This factor can depend
on the dynamical variables, typically as a function of , and can influence
the semiclassical dynamics of the (2+1)-dimensional spacetime.
These results shall be significant from the viewpoint of quantum gravity.Comment: 21 pages. To appear in Physical Review D. The discussion on the
path-integral domain for the shift vector has been adde
Family–Teacher Relationships and Child Engagement in Early Care and Education
Young children’s positive interactions with teachers and peers in early care and education (ECE) settings support the development of their social and academic skills. Identifying malleable factors that contribute to children’s positive engagement in these interactions is important in supporting early development. The current study examines one potential malleable factor that could be bolstered through supports for families and teachers alike: family–teacher relationships. We investigate associations between three specific domains of family–teacher relationships and children’s engagement in ECE, so that findings are specific and relevant to intervention. We examine data from Oregon’s Quality Rating Improvement System Validation Study; a diverse sample of 492 preschool-aged children in center-based ECE participated. Children’s engagement was directly observed; parents reported their perception of family–teacher relationships. Multilevel models examined the associations between family–teacher relationships and children’s positive engagement with teachers and peers in ECE classrooms. Results indicate a positive significant relationship between practices and children’s positive engagement with teachers. Although this association was not causal, it suggests that teachers who collaborate and communicate with families, respond to family feedback and cultural values, and demonstrate a family-focused concern may help children engage more positively with teachers. Findings are discussed, limitations addressed, and future directions provided
Valence band offset of the ZnO/AlN heterojunction determined by X-ray photoemission spectroscopy
The valence band offset of ZnO/AlN heterojunctions is determined by high resolution x-ray photoemission spectroscopy. The valence band of ZnO is found to be 0.43±0.17 eV below that of AlN. Together with the resulting conduction band offset of 3.29±0.20 eV, this indicates that a type-II (staggered) band line up exists at the ZnO/AlN heterojunction. Using the III-nitride band offsets and the transitivity rule, the valence band offsets for ZnO/GaN and ZnO/InN heterojunctions are derived as 1.37 and 1.95 eV, respectively, significantly higher than the previously determined values
Initial psychological responses to influenza A, H1N1 ("Swine flu")
Background
The outbreak of the pandemic flu, Influenza A H1N1 (Swine Flu) in early 2009, provided a major challenge to health services around the world. Previous pandemics have led to stockpiling of goods, the victimisation of particular population groups, and the cancellation of travel and the boycotting of particular foods (e.g. pork). We examined initial behavioural and attitudinal responses towards Influenza A, H1N1 ("Swine flu") in the six days following the WHO pandemic alert level 5, and regional differences in these responses.
Methods
328 respondents completed a cross-sectional Internet or paper-based questionnaire study in Malaysia (N = 180) or Europe (N = 148). Measures assessed changes in transport usage, purchase of preparatory goods for a pandemic, perceived risk groups, indicators of anxiety, assessed estimated mortality rates for seasonal flu, effectiveness of seasonal flu vaccination, and changes in pork consumption
Results
26% of the respondents were 'very concerned' about being a flu victim (42% Malaysians, 5% Europeans, p < .001). 36% reported reduced public transport use (48% Malaysia, 22% Europe, p < .001), 39% flight cancellations (56% Malaysia, 17% Europe, p < .001). 8% had purchased preparatory materials (e.g. face masks: 8% Malaysia, 7% Europe), 41% Malaysia (15% Europe) intended to do so (p < .001). 63% of Europeans, 19% of Malaysians had discussed the pandemic with friends (p < .001). Groups seen as at 'high risk' of infection included the immune compromised (mentioned by 87% respondents), pig farmers (70%), elderly (57%), prostitutes/highly sexually active (53%), and the homeless (53%). In data collected only in Europe, 64% greatly underestimated the mortality rates of seasonal flu, 26% believed seasonal flu vaccination gave protection against swine flu. 7% had reduced/stopped eating pork. 3% had purchased anti-viral drugs for use at home, while 32% intended to do so if the pandemic worsened.
Conclusion
Initial responses to Influenza A show large regional differences in anxiety, with Malaysians more anxious and more likely to reduce travel and to buy masks and food. Discussions with family and friends may reinforce existing anxiety levels. Particular groups (homosexuals, prostitutes, the homeless) are perceived as at greater risk, potentially leading to increased prejudice during a pandemic. Europeans underestimated mortality of seasonal flu, and require more information about the protection given by seasonal flu inoculation
Comparison of Current Sarcopenia Classification Criteria in Older New England Women
Objectives: To evaluate the prevalence of sarcopenia in a sample of older, sedentary women using criteria from the European Working Group on Sarcopenia in Older People (EWGSOP), the International Working Group (IWG), and the Foundation for the National Institutes of Health Sarcopenia Project (FNIHSP). Design: Cross-sectional analysis. Setting and Participants: Community-dwelling women (n = 61) aged 71.9 ± 4.6 years (mean±SD) with a BMI 27.3 ± 6.0 kg/m2 who by self-report were healthy and did not exercise were recruited and evaluated for sarcopenia. Measurements: Height, weight, grip strength, gait speed, and appendicular lean mass (via segmental multi-frequency bioelectrical impedance analysis: SMF-BIA) were measured. Prevalence was reported using descriptive statistics and a Fisher’s exact test was used to analyze the distribution frequency of sarcopenia classification by different criteria. Results: In this sample 14.8% met EWGSOP criteria, 6.6% met FNIHSP criteria, and 3.3% met IWG criteria. There was a borderline significant difference in distribution frequency between EWGSOP and IWG classification criteria (p=0.053). Conclusion: The variation in sarcopenia prevalence depending on the diagnostic criteria used is consistent with previous research and there are borderline significant differences between classification criteria in this population. These data suggest the need for additional examination to determine current cut points for ALM measured by SMF-BIA, as well as which established definition of sarcopenia is appropriate for this population
Deformation Quantization of Bosonic Strings
Deformation quantization of bosonic strings is considered. We show that the
light-cone gauge is the most convenient classical description to perform the
quantization of bosonic strings in the deformation quantization formalism.
Similar to the field theory case, the oscillator variables greatly facilitates
the analysis. The mass spectrum, propagators and the Virasoro algebra are
finally described within this deformation quantization scheme.Comment: 33+1 pages, harvmac file, no figure
Tower and Aircraft Eddy Covariance Measurements of Water Vapor, Energy, and Carbon Dioxide Fluxes during SMACEX
Abstract
A network of eddy covariance (EC) and micrometeorological flux (METFLUX) stations over corn (Zea mays L.) and soybean [Glycine max (L.) Merr.] canopies was established as part of the Soil Moisture–Atmosphere Coupling Experiment (SMACEX) in central Iowa during the summer of 2002 to measure fluxes of heat, water vapor, and carbon dioxide (CO2) during the growing season. Additionally, EC measurements of water vapor and CO2 fluxes from an aircraft platform complemented the tower-based measurements. Sensible heat, water vapor, and CO2 fluxes showed the greatest spatial and temporal variability during the early crop growth stage. Differences in all of the energy balance components were detectable between corn and soybean as well as within similar crops throughout the study period. Tower network–averaged fluxes of sensible heat, water vapor, and CO2 were observed to be in good agreement with area-averaged aircraft flux measurements
Psychology as a natural science in the eighteenth century
Psychology considered as a natural science began as Aristotelian "physics" or "natural philosophy" of the soul. C. Wolff placed psychology under metaphysics, coordinate with cosmology. Scottish thinkers placed it within moral philosophy, but distinguished its "physical" laws from properly moral laws (for guiding conduct). Several Germans sought to establish an autonomous empirical psychology as a branch of natural science. British and French visual theorists developed mathematically precise theories of size and distance perception; they created instruments to test these theories and to measure visual phenomena such as the duration of visual impressions. These investigators typically were dualists who included mental phenomena within nature
Implications of invariance of the Hamiltonian under canonical transformations in phase space
We observe that, within the effective generating function formalism for the
implementation of canonical transformations within wave mechanics, non-trivial
canonical transformations which leave invariant the form of the Hamilton
function of the classical analogue of a quantum system manifest themselves in
an integral equation for its stationary state eigenfunctions. We restrict
ourselves to that subclass of these dynamical symmetries for which the
corresponding effective generating functions are necessaarily free of quantum
corrections. We demonstrate that infinite families of such transformations
exist for a variety of familiar conservative systems of one degree of freedom.
We show how the geometry of the canonical transformations and the symmetry of
the effective generating function can be exploited to pin down the precise form
of the integral equations for stationary state eigenfunctions. We recover
several integral equations found in the literature on standard special
functions of mathematical physics. We end with a brief discussion (relevant to
string theory) of the generalization to scalar field theories in 1+1
dimensions.Comment: REVTeX v3.1, 13 page
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