Bayesian inference of a negative quantity from positive measurement results

In this paper the Bayesian analysis is applied to assign a probability density to the value of a quantity having a definite sign. This analysis is logically consistent with the results, positive or negative, of repeated measurements. Results are used to estimate the atom density shift in a caesium fountain clock. The comparison with the classical statistical analysis is also reported and the advantages of the Bayesian approach for the realization of the time unit are discussed.Comment: 10 pages, 4 figures, submitted to Metrologi

Cosmic variance of the galaxy cluster weak lensing signal

Intrinsic variations of the projected density profiles of clusters of galaxies at fixed mass are a source of uncertainty for cluster weak lensing. We present a semi-analytical model to account for this effect, based on a combination of variations in halo concentration, ellipticity and orientation, and the presence of correlated haloes. We calibrate the parameters of our model at the 10 per cent level to match the empirical cosmic variance of cluster profiles at M_200m=10^14...10^15 h^-1 M_sol, z=0.25...0.5 in a cosmological simulation. We show that weak lensing measurements of clusters significantly underestimate mass uncertainties if intrinsic profile variations are ignored, and that our model can be used to provide correct mass likelihoods. Effects on the achievable accuracy of weak lensing cluster mass measurements are particularly strong for the most massive clusters and deep observations (with ~20 per cent uncertainty from cosmic variance alone at M_200m=10^15 h^-1 M_sol and z=0.25), but significant also under typical ground-based conditions. We show that neglecting intrinsic profile variations leads to biases in the mass-observable relation constrained with weak lensing, both for intrinsic scatter and overall scale (the latter at the 15 per cent level). These biases are in excess of the statistical errors of upcoming surveys and can be avoided if the cosmic variance of cluster profiles is accounted for.Comment: 14 pages, 6 figures; submitted to MNRA

Asymptotic scaling in the two-dimensional SU(3)SU(3) σ\sigma-model at correlation length 4×1054 \times 10^5

We carry out a high-precision simulation of the two-dimensional $SU(3)$ principal chiral model at correlation lengths $\xi$ up to $\approx\! 4 \times 10^5$, using a multi-grid Monte Carlo (MGMC) algorithm. We extrapolate the finite-volume Monte Carlo data to infinite volume using finite-size-scaling theory, and we discuss carefully the systematic and statistical errors in this extrapolation. We then compare the extrapolated data to the renormalization-group predictions. For \xi \gtapprox 10^3 we observe good asymptotic scaling in the bare coupling; at $\xi \approx 4 \times 10^5$ the nonperturbative constant is within 2--3\% of its predicted limiting value.Comment: 13 pages (includes 3 figures), self-unpacking uuencoded .tar.g

Genetic and antigenic characterisation of serotype A FMD viruses from East Africa to select new vaccine strains

Vaccine strain selection for emerging foot-and-mouth disease virus (FMDV) outbreaks in enzootic countries can be addressed through antigenic and genetic characterisation of recently circulating viruses. A total of 56 serotype A FMDVs isolated between 1998 and 2012, from Central, East and North African countries were characterised antigenically by virus neutralisation test using antisera to three existing and four candidate vaccine strains and, genetically by characterising the full capsid sequence data. A Bayesian analysis of the capsid sequence data revealed the viruses to be of either African or Asian topotypes with subdivision of the African topotype viruses into four genotypes (Genotypes I, II, IV and VII). The existing vaccine strains were found to be least cross-reactive (good matches observed for only 5.4–46.4% of the sampled viruses). Three bovine antisera, raised against A-EA-2007, A-EA-1981 and A-EA-1984 viruses, exhibited broad cross-neutralisation, towards more than 85% of the circulating viruses. Of the three vaccines, A-EA-2007 was the best showing more than 90% in-vitro cross-protection, as well as being the most recent amongst the vaccine strains used in this study. It therefore appears antigenically suitable as a vaccine strain to be used in the region in FMD control programmes

Ovarian Steroid Hormones and Auditory Function

Considerable anecdotal evidence and information from previous studies suggest that auditory function may be influenced by hormones. This thesis reviews in detail the potential role of hormones in modulating the auditory system and in the development of pathological conditions in the auditory system with an emphasis on the effect of the ovarian hormones. Ovarian steroids may influence auditory function directly through their receptors, which have been detected in the auditory system, or indirectly through their effects on the blood supply, the fluid electrolyte balance of the cochlea, and the neurotransmitters of the auditory system. Effects on other parts of the central nervous system connected to the auditory system may also be of importance. The aim of the study was to investigate whether physiological alterations in ovarian hormones in women with normal hearing, during the natural ovarian cycle and assisted conception treatment were associated with changes in auditory function at the cochlear and brain stem level, and whether these variations were not seen in men over a similar period of time. The auditory tests evaluated auditory function from the outer ear to the brainstem in both the afferent and efferent system. Hormone levels were assayed only in the female subjects at the same time as the auditory testing, four times during the ovarian cycle, or three times during the assisted conception treatment. Auditory tests were undertaken in the male subjects once a week for four consecutive weeks to correspond with the ovarian cycle measurements. A number of changes in auditory function were observed during the ovarian cycle and assisted conception treatment, and gender differences were noted. The OAE results may suggest either excitation of the cochlea with higher levels of oestrogen, or suppression of the cochlea with higher level of progesterone. The longer ABR latency following ovarian stimulation and in the follicular phase of the ovarian cycle is consistent with the inhibitory effect of neurosteroids on ABR associated with higher levels of oestrogen. The variation in auditory function were not observed in men

Adapting Hybrid ANN/HMM to Speech Variations

A technique is proposed for the adaptation of automatic speech recognition systems using Hybrid models combining Artificial Neural Networks with Hidden Markov Models. We investigated in this paper the extension of the classical approach consisting in applying linear transformations not only to the input features, but also to the outputs of the internal layers. The motivation is that the outputs of an internal layer represent a projection of the input pattern into a space where it should be easier to learn the classification or transformation expected at the output of the network. To reduce the risk that the network focuses on new data only, loosing its generalization capability (catastrophic forgetting), an original solution, Conservative Training is proposed. We illustrate the problem of catastrophic forgetting using an artificial test-bed, and apply our techniques to a set of adaptation tasks in the domain of Automatic Speech Recognition (ASR) based on Artificial Neural Networks. We report on the adaptation potential of different techniques, and on the generalization capability of the adapted networks. The results show that the combination of the proposed approaches mitigates the catastrophic forgetting effects, and always outperforms the use of the classical linear transformation in the feature space. 1

Evaluasi Keamanan dan Manfaat Ramuan Jamu untuk Hiperurisemia

Hyperuricemia is a condition where there is an elevated blood uric acid level above normal range. Hyperuricemia occurs due to increased uric acid metabolism, decreased uric acid expenditure, or a combination of both. The Jamu formula containingPiper retrofractum, Plantago majorandApiumgraveolens have the potential to overcome hyperuricemia. This study aims to evaluate the safety and efficacy of formula inhuman subjects with hyperuricemia. The method used was pre and posttest design for 28 days. Safety parameters were assessed by renal function (urea and creatinine) and liver function (SGOT and SGPT). The parameters of efficacy were measured by uric acid change (H0, H14, and H28), improvement of clinical symptoms and quality of life (SF-36). This study showed that kidney and liver function still in the normal rangeafter28 days of intervention. The levels of uric acid showed a significant decrease (p <0.05). Clinical symptoms of the subjectsimproved after 17 daysofintervention. SF-36indicated significant improvement (p <0.05). It can be concluded that the formula was proved to be safe and effective for 28 daysof intervention

Effects of the gg-factor in semi-classical kinetic plasma theory

A kinetic theory for spin plasmas is put forward, generalizing those of previous authors. In the model, the ordinary phase space is extended to include the spin degrees of freedom. Together with Maxwell's equations, the system is shown to be energy conserving. Analysing the linear properties, it is found that new types of wave-particle resonances are possible, that depend directly on the anomalous magnetic moment of the electron. As a result new wave modes, not present in the absence of spin, appear. The implications of our results are discussed.Comment: 4 pages, two figures, version to appear in Physical Review Letter