Shape Space Methods for Quantum Cosmological Triangleland

With toy modelling of conceptual aspects of quantum cosmology and the problem of time in quantum gravity in mind, I study the classical and quantum dynamics of the pure-shape (i.e. scale-free) triangle formed by 3 particles in 2-d. I do so by importing techniques to the triangle model from the corresponding 4 particles in 1-d model, using the fact that both have 2-spheres for shape spaces, though the latter has a trivial realization whilst the former has a more involved Hopf (or Dragt) type realization. I furthermore interpret the ensuing Dragt-type coordinates as shape quantities: a measure of anisoscelesness, the ellipticity of the base and apex's moments of inertia, and a quantity proportional to the area of the triangle. I promote these quantities at the quantum level to operators whose expectation and spread are then useful in understanding the quantum states of the system. Additionally, I tessellate the 2-sphere by its physical interpretation as the shape space of triangles, and then use this as a back-cloth from which to read off the interpretation of dynamical trajectories, potentials and wavefunctions. I include applications to timeless approaches to the problem of time and to the role of uniform states in quantum cosmological modelling.Comment: A shorter version, as per the first stage in the refereeing process, and containing some new reference

Mean-field model of the ferromagnetic ordering in the superconducting phase of ErNi_2B_2C

A mean-field model explaining most of the details in the magnetic phase diagram of ErNi_2B_2C is presented. The low-temperature magnetic properties are found to be dominated by the appearance of long-period commensurate structures. The stable structure at low temperatures and zero field is found to have a period of 40 layers along the a direction, and upon cooling it undergoes a first-order transition at T_C = 2.3 K to a different 40-layered structure having a net ferromagnetic component of about 0.4 mu_B/Er. The neutron-diffraction patterns predicted by the two 40-layered structures, above and below T_C, are in agreement with the observations of Choi et al.Comment: 4 pages, 3 figures (Revtex4

HIV Testing and Conspiracy Beliefs Regarding the Origins of HIV among African Americans

Abstract Conspiracy beliefs regarding the origins of HIV are common among African Americans, and have been associated with engaging in HIV risk behaviors but also with earlier diagnosis among HIV patients. The objective of the present study was to test the association of HIV serostatus testing with conspiracy beliefs. A total of 1430 African Americans from low-income neighborhoods with high rates of drug use were surveyed in 1997-1999 in face-to-face interviews. Two 4-point items assessed if participants agreed that AIDS was started by an experiment that went wrong and AIDS was created to kill blacks and poor folks. A binary variable indicated if the respondent agreed with the statements, on average. 22.5% of the sample endorsed conspiracy beliefs, 4.0% of whom reported not having had an HIV test, compared to 7.7% of those who did not endorse conspiracy beliefs. In multivariable logistic regression modeling, never having had an HIV test was significantly associated with conspiracy beliefs (adjusted odds ratio [AOR]=0.43, 95% confidence interval [CI]=1.3-4.3), having a high school education (AOR=0.55, CI=0.35-0.84), having depression (AOR=1.61, CI=1.02-2.52), female gender (AOR=0.54, CI=0.34-0.86), younger age, and a history of injection drug use (AOR=0.36, CI=0.23-0.56), but not sex risk behaviors (multiple partners, irregular condom use). The finding that individuals who have conspiracy beliefs are more likely to have been tested for HIV may partially explain why HIV-positive individuals who endorse conspiracy beliefs are more likely to obtain an earlier diagnosis.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/78123/1/apc.2009.0061.pd

Irish athletes’ attitudes towards seeking sport psychology consultation

The aim of this study was to replicate previous research examining attitudes to sport psychology consultation conducted in the United States, Germany, and United Kingdom (Martin, Lavallee, Kellmann & Page, 2004), and New Zealand (Anderson, Hodge, Lavallee, & Martin, 2004). The study employed the Sport Psychology Attitudes-Revised (SPA-R) questionnaire (Martin, Kellman, Lavallee & Page, 2002) in order to develop an understanding of the attitudes elite Irish athletes (N=240) hold toward sport psychology and also compare these attitudes with those found in other countries. Irish athletes in this study reported a generally positive attitude toward sport psychology provision overall, and also were identified as being open to receiving sport psychology assistance, reported moderately high levels of confidence in sport psychology, and indicated the lack of accessibility and availability to these services as distinguishing factors. Comparison of results with athletes from other countries suggested that positive attitudes toward sport psychology may be based on factors not directly associated with personal experiences of sport psychology. As the provision of sport psychology increases, practitioners need to better understand athletes' attitudes toward sport psychology so they can tailor their services to best meet the needs of athletes. In order to do this, further research related to cultural and national differences is required

Exclusion statistics: A resolution of the problem of negative weights

We give a formulation of the single particle occupation probabilities for a system of identical particles obeying fractional exclusion statistics of Haldane. We first derive a set of constraints using an exactly solvable model which describes an ideal exclusion statistics system and deduce the general counting rules for occupancy of states obeyed by these particles. We show that the problem of negative probabilities may be avoided with these new counting rules.Comment: REVTEX 3.0, 14 page

Biotic indicators for ecological state change in Amazonian floodplains

Riverine floodplains are biologically diverse and productive ecosystems. Although tropical floodplains remain relatively conserved and ecologically functional compared to those at higher latitudes, they face accelerated hydropower development, climate change, and deforestation. Alterations to the flood pulse could act synergistically with other drivers of change to promote profound ecological state change at a large spatial scale. State change occurs when an ecosystem reaches a critical threshold or tipping point, which leads to an alternative qualitative state for the ecosystem. Visualizing an alternative state for Amazonian floodplains is not straightforward. Yet, it is critical to recognize that changes to the flood pulse could push tropical floodplain ecosystems over a tipping point with cascading adverse effects on biodiversity and ecosystem services. We characterize the Amazonian flood pulse regime, summarize evidence of flood pulse change, assess potential ecological repercussions, and provide a monitoring framework for tracking flood pulse change and detecting biotic responses

CuSiO_3 : a quasi - one - dimensional S=1/2 antiferromagnetic chain system

CuSiO_3, isotypic to the spin - Peierls compound CuGeO_3, was discovered recently as a metastable decomposition product of the silicate mineral dioptase, Cu_6Si_6O_{18}\cdot6H_2O. We investigated the physical properties of CuSiO_3 using susceptibility, magnetization and specific heat measurements on powder samples. The magnetic susceptibility \chi(T) is reproduced very well above T = 8 K by theoretical calculations for an S=1/2 antiferromagnetic Heisenberg linear chain without frustration (\alpha = 0) and a nearest - neighbor exchange coupling constant of J/k_{B} = 21 K, much weaker than in CuGeO_3. Below 8 K the susceptibility exhibits a substantial drop. This feature is identified as a second - order phase transition at T_{0} = 7.9 K by specific heat measurements. The influence of magnetic fields on T_{0} is weak, and ac - magnetization measurements give strong evidence for a spin - flop - phase at \mu_0H_{SF} ~ 3 T. The origin of the magnetic phase transition at T_{0} = 7.9 K is discussed in the context of long - range antiferromagnetic order (AF) versus spin - Peierls(SP)order. Susceptibility and specific heat results support the AF ordered ground state. Additional temperature dependent ^{63,65}Cu nuclear quadrupole resonance experiments have been carried out to probe the Cu^{2+} electronic state and the spin dynamics in CuSiO_3

Relationship of Dental Caries and Fluorosis to Fluoride Supplement History in a Non-Fluoridated Sample of Schoolchildren

A random sample of 206 Michigan children, aged from 9 to 13, were examined for fluorosis from a larger group of 2038 children participating in a dental project. Clinical examinations included caries data (DMFS) and assessment of fluorosis by use of the Tooth Surface Index of Fluorosis (TSIF). Separate examiners were used for each index. The response rate of a questionnaire mailed to parents to gather information on residence histories, use of fluoride supplements, and antibiotics was 78%. The prevalence of fluorosis was about 20% among the respondents. Of the 4868 tooth surfaces examined, 9.2% were affected by fluorosis. In all cases, dental fluorosis was judged as mild, with most occurrences on the posterior teeth. No instances of moderate or severe fluorosis were found. The caries experience of respondents was 1.69 ± 2.73 DMFS. Caries experience does not appear to be significantly related to income, education, or fluoride supplement use. Approximately 52% of respondents were reported to have taken fluoride supplements with various degrees of consistency. Parents' education was positively related to both prevalence of fluorosis (odds ratio = 2.2) and use of fluoride supplements (odds ratio = 2.7). No significant relation was revealed with evidence of fluorosis and use of supplements. This study shows a relatively mild level of dental fluorosis in a sample of children from a non-fluoridated area. Dental fluorosis in this group does not appear to be related to use of fluoride supplements or differences in caries experience.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66503/2/10.1177_08959374890030021501.pd

Observation of a kilogram-scale oscillator near its quantum ground state

We introduce a novel cooling technique capable of approaching the quantum ground state of a kilogram-scale system-an interferometric gravitational wave detector. The detectors of the Laser Interferometer Gravitational-wave Observatory (LIGO) operate within a factor of 10 of the standard quantum limit (SQL), providing a displacement sensitivity of 10−18 m in a 100 Hz band centered on 150 Hz. With a new feedback strategy, we dynamically shift the resonant frequency of a 2.7 kg pendulum mode to lie within this optimal band, where its effective temperature falls as low as 1.4 μK, and its occupation number reaches about 200 quanta. This work shows how the exquisite sensitivity necessary to detect gravitational waves can be made available to probe the validity of quantum mechanics on an enormous mass scale

Zero-divisor graphs of nilpotent-free semigroups

We find strong relationships between the zero-divisor graphs of apparently disparate kinds of nilpotent-free semigroups by introducing the notion of an \emph{Armendariz map} between such semigroups, which preserves many graph-theoretic invariants. We use it to give relationships between the zero-divisor graph of a ring, a polynomial ring, and the annihilating-ideal graph. Then we give relationships between the zero-divisor graphs of certain topological spaces (so-called pearled spaces), prime spectra, maximal spectra, tensor-product semigroups, and the semigroup of ideals under addition, obtaining surprisingly strong structure theorems relating ring-theoretic and topological properties to graph-theoretic invariants of the corresponding graphs.Comment: Expanded first paragraph in section 6. To appear in J. Algebraic Combin. 22 page