5,458 research outputs found
Recent trends in the incidence of anxiety diagnoses and symptoms in primary care.
Anxiety is common, with significant morbidity, but little is known about presentations and recording of anxiety diagnoses and symptoms in primary care. This study aimed to determine trends in incidence and socio-demographic variation in General Practitioner (GP) recorded diagnoses of anxiety, mixed anxiety/depression, panic and anxiety symptoms
The AF structure of non commutative toroidal Z/4Z orbifolds
For any irrational theta and rational number p/q such that q|qtheta-p|<1, a
projection e of trace q|qtheta-p| is constructed in the the irrational rotation
algebra A_theta that is invariant under the Fourier transform. (The latter is
the order four automorphism U mapped to V, V mapped to U^{-1}, where U, V are
the canonical unitaries generating A_theta.) Further, the projection e is
approximately central, the cut down algebra eA_theta e contains a Fourier
invariant q x q matrix algebra whose unit is e, and the cut downs eUe, eVe are
approximately inside the matrix algebra. (In particular, there are Fourier
invariant projections of trace k|qtheta-p| for k=1,...,q.) It is also shown
that for all theta the crossed product A_theta rtimes Z_4 satisfies the
Universal Coefficient Theorem. (Z_4 := Z/4Z.) As a consequence, using the
Classification Theorem of G. Elliott and G. Gong for AH-algebras, a theorem of
M. Rieffel, and by recent results of H. Lin, we show that A_theta rtimes Z_4 is
an AF-algebra for all irrational theta in a dense G_delta.Comment: 35 page
Study of Optimal Perimetric Testing In Children (OPTIC): Normative visual field values in children
Purpose: We sought to define normative visual field (VF) values for children using common clinical test protocols for kinetic and static perimetry. Design: Prospective, observational study. Subjects: We recruited 154 children aged 5 to 15 years without any ophthalmic condition that would affect the VF (controls) from pediatric clinics at Moorfields Eye Hospital. Methods: Children performed perimetric assessments in a randomized order using Goldmann and Octopus kinetic perimetry, and Humphrey static perimetry (Swedish Interactive Thresholding Algorithm [SITA] 24-2 FAST), in a single sitting, using standardized clinical protocols, with assessment by a single examiner. Unreliable results (assessed qualitatively) were excluded from the normative data analysis. Linear, piecewise, and quantile mixed-effects regression models were used. We developed a method to display age-specific normative isopters graphically on a VF plot to aid interpretation. Main Outcome Measures: Summary measures and graphical plots describing normative VF data for 3 common perimetric tests. Results: Visual field area increased with age on testing with Goldmann isopters III4e, I4e, and I2e (linear regression; P < 0.001) and for Octopus isopters III4e and I4e (linear regression; P < 0.005). Visual field development occurs predominately in the infero-temporal field. Humphrey mean deviation (MD) showed an increase of 0.3 decibels (dB; 95% CI, 0.21-0.40) MD per year up to 12 years of age, when adult MD values were reached and thereafter maintained. Conclusions: Visual field size and sensitivity increase with age in patterns that are specific to the perimetric approach used. These developmental changes should be accounted for when interpreting perimetric test results in children, particularly when monitoring change over time
High Harmonic Generation in SF: Raman-excited Vibrational Quantum Beats
In a recent experiment (N. Wagner et al., PNAS v103, p13279) on SF, a
high-harmonic generating laser pulse is preceded by a pump pulse which
stimulates Raman-active modes in the molecule. Varying the time delay between
the two pulses modulates high harmonic intensity, with frequencies equal to the
vibration frequencies of the Raman-active modes. We propose an explanation of
this modulation as a quantum interference between competing pathways that occur
via adjacent vibrational states of the molecule. The Raman and high harmonic
processes act as beamsplitters, producing vibrational quantum beats among the
Raman-active vibrational modes that are excited by the first pulse. We
introduce a rigorous treatment of the electron-ion recombination process and
the effect of the ionic Coulomb field in the electron propagation outside the
molecule, improving over the widely-used three-step model.Comment: submitted to PR
Black Hole Entropy, Topological Entropy and the Baum-Connes Conjecture in K-Theory
We shall try to exhibit a relation between black hole entropy and topological
entropy using the famous Baum-Connes conjecture for foliated manifolds which
are particular examples of noncommutative spaces. Our argument is qualitative
and it is based on the microscopic origin of the Beckenstein-Hawking
area-entropy formula for black holes, provided by superstring theory, in the
more general noncommutative geometric context of M-Theory following the Connes-
Douglas-Schwarz article.Comment: 17 pages, Latex, contains an important paragraph in section 2 which
gives a better understandin
Product-free sets in the free semigroup
In this paper, we study product-free subsets of the free semigroup over a finite alphabet A. We prove that the maximum density of a product-free subset of the free semigroup over A, with respect to the natural measure that assigns a weight of |A|−n to each word of length n, is precisely 1∕2
Equilibrium states and invariant measures for random dynamical systems
Random dynamical systems with countably many maps which admit countable
Markov partitions on complete metric spaces such that the resulting Markov
systems are uniformly continuous and contractive are considered. A
non-degeneracy and a consistency conditions for such systems, which admit some
proper Markov partitions of connected spaces, are introduced, and further
sufficient conditions for them are provided. It is shown that every uniformly
continuous Markov system associated with a continuous random dynamical system
is consistent if it has a dominating Markov chain. A necessary and sufficient
condition for the existence of an invariant Borel probability measure for such
a non-degenerate system with a dominating Markov chain and a finite (16) is
given. The condition is also sufficient if the non-degeneracy is weakened with
the consistency condition. A further sufficient condition for the existence of
an invariant measure for such a consistent system which involves only the
properties of the dominating Markov chain is provided. In particular, it
implies that every such a consistent system with a finite Markov partition and
a finite (16) has an invariant Borel probability measure. A bijective map
between these measures and equilibrium states associated with such a system is
established in the non-degenerate case. Some properties of the map and the
measures are given.Comment: The article is published in DCDS-A, but without the 3rd paragraph on
page 4 (the complete removal of the paragraph became the condition for the
publication in the DCDS-A after the reviewer ran out of the citation
suggestions collected in the paragraph
Relative risks of cardiovascular disease in people prescribed olanzapine, risperidone and quetiapine
ABSTRACT: Antipsychotics may confer long term benefits and risks, including cardiovascular disease (CVD) risk. Several studies using routine clinical data have reported associations between antipsychotics and CVD but potential confounding factors and unclear classification of drug exposure limits their interpretation.
METHOD: We used data from The Health Improvement Network, a large UK primary care database to determine relative risks of (CVD) comparing similar groups of people only prescribed olanzapine versus either risperidone or quetiapine. We included participants over 18 between 1995 and 2011. To assess confounding factors we created propensity scores for being prescribed each antipsychotic. We used propensity score matching and Poisson regression to calculate the CVD incidence rate ratios for olanzapine versus the other two drugs.
RESULTS: We identified 18,319 people who received a single antipsychotic during follow-up (n = 5090 risperidone, 7797 olanzapine and 4613 quetiapine). In unmatched analyses, the CVD incidence rate ratio (IRR) for olanzapine versus risperidone was 0.63 (0.51–0.77) but the propensity score matched IRR was 0.78 (0.61–1.02). In the unmatched olanzapine versus quetiapine analysis the IRR adjusted for age and sex for olanzapine was 1.52 (1.16–1.98) but the propensity score matched analysis gave an IRR of 1.08 (0.79–1.46).
CONCLUSIONS: After propensity score matching, we found no statistical differences in CVD incidence between olanzapine and either risperidone or quetiapine. Analyses which did not account for confounding factors produced very different results. Researchers must address confounding factors when designing observational studies to assess adverse outcomes of drugs, including antipsychotics
Statin prescribing for people with severe mental illnesses: a staggered cohort study of 'real-world' impacts
OBJECTIVES: To estimate the 'real-world effectiveness of statins for primary prevention of cardiovascular disease (CVD) and for lipid modification in people with severe mental illnesses (SMI), including schizophrenia and bipolar disorder. DESIGN: Series of staggered cohorts. We estimated the effect of statin prescribing on CVD outcomes using a multivariable Poisson regression model or linear regression for cholesterol outcomes. SETTING: 587 general practice (GP) surgeries across the UK reporting data to The Health Improvement Network. PARTICIPANTS: All permanently registered GP patients aged 40-84 years between 2002 and 2012 who had a diagnosis of SMI. Exclusion criteria were pre-existing CVD, statin-contraindicating conditions or a statin prescription within the 24 months prior to the study start. EXPOSURE: One or more statin prescriptions during a 24-month 'baseline' period (vs no statin prescription during the same period). MAIN OUTCOME MEASURES: The primary outcome was combined first myocardial infarction and stroke. All-cause mortality and total cholesterol concentration were secondary outcomes. RESULTS: We identified 2944 statin users and 42 886 statin non-users across the staggered cohorts. Statin prescribing was not associated with significant reduction in CVD events (incident rate ratio 0.89; 95% CI 0.68 to 1.15) or all-cause mortality (0.89; 95% CI 0.78 to 1.02). Statin prescribing was, however, associated with statistically significant reductions in total cholesterol of 1.2 mmol/L (95% CI 1.1 to 1.3) for up to 2 years after adjusting for differences in baseline characteristics. On average, total cholesterol decreased from 6.3 to 4.6 in statin users and 5.4 to 5.3 mmol/L in non-users. CONCLUSIONS: We found that statin prescribing to people with SMI in UK primary care was effective for lipid modification but not CVD events. The latter finding may reflect insufficient power to detect a smaller effect size than that observed in randomised controlled trials of statins in people without SMI
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