On Axially-Symmetric Finite-Energy Monopole Configurations

Axially symmetric finite energy monopole configurations are investigated for the gauge group SO(3) with the Higgs field in the adjoint representation. To avoid the complications due to gauge freedom gauge invariant fields are introduced and used throughout. From topological and continuity considerations it is argued that the only regular axially symmetric magnetic charge distributions permitted are isolated charges of uniform strength and alternate sign located along the axis of symmetry. In particular, if there is only one sign, the magnetic charge must be located at a single point. For a zero Higgs potential the minimal energy (first order Bogomolny) field equations take a simple form when written in terms of the gauge-invariant fields. In general, there are nine equations for nine (axially symmetric) fields, but these reduce to five equations for five fields if a further symmetry (invariance under reflexions in planes through the axis of symmetry) is imposed. Remarkably, four of the equations are the same whether the reflexion symmetry is imposed or not, and these four equations can be completely solved in terms of a master potential. From these and the remaining equations (just one in the case of mirror symmetry) the asymptotic behaviour of the functions at large distances and in the neighbourhood of the origin (location of charge) is obtained and studied in some detail

On Monopole Systems with Weak Axial Syrnmetry

Let (Φ,A) be an SO(3) Yang-Mills-Higgs system which is a real-analytic static, finite-energy solution of the Bogomolny field equations B = DΦ. We show that the zero-set of the current J = (Φ_Λ)DΦ is of dimension at most one. Using this property of J we obtain the curious result that if the system is axially symmetric, in the weak sense that all local scalar gauge-invariants are axially symmetric, the topological charges must be located on the axis of symmetry and must be of equal magnitude and alternate sign. In particular, if the charges are of uniform sign they must be concentrated at a single point. The fact that the charges of spherically symmetric monopoles are bounded by unity is obtained as a corollary. It is also shown that a master-potential for the invariant fields that was found earlier to exist for systems with additional symmetry, exists as a direct consequence of weak axial symmetry alone

Neurocysticercosis: experience with diagnosis by ELISA serology and computerised tomography in Zimbabwe

A research paper on the effectiveness of a new technological method to ascertain HIV antigens in the blood of Zimbabwean patients in the early 1990's.Over a three-year period, 646 sera from 630 patients with signs and symptoms compatible with neurocysticercosis were investigated for antibodies to cysticcrcal antigens using an ELISA test. Overall, 12 pc specimens were positive. The sensitivity of the ELISA, when compared with a limited number of computerised tomography investigations, was over 70 pc. False negative serology was associated with HIV infection in some patients. The positive predictive value was 87 pc and the negative predictive value was 85 pc when patients with active infection, potentially amenable to chemotherapy, were considered. The specificity, determined from serological tests of patients with a variety of trematode, cestode and other infections, was over 90 pc. Three of 11 patients with intestinal taeniasis, and each of two patients with hydatid disease were seropositive. The results suggest the value of ELIS A serology as a more cost-effective diagnostic method for all patients with suspected cysticercosis

Long term variability of the cosmic ray intensity

In a previous paper Bhat, et al., assess the evidence for the continuing acceleration of cosmic rays in the Loop I supernova remnant. The enhanced gamma-ray emission is found consistent with the Blandford and Cowie model for particle acceleration at the remnant shock wave. The contributions of other supernovae remnants to the galactic cosmic ray energy density are now considered, paying anisotropy of cosmic rays accelerated by local supernovae ( 100 pc). The results are compared with geophysical data on the fluctuations in the cosmic ray intensity over the previous one billion years

Photodissociation of Ozone in the Hartley Band: Potential Energy Surfaces, Nonadiabatic Couplings, and Singlet/Triplet Branching Ratio

The lowest five 1A\u27states of ozone, involved in the photodissociation with UV light, are analyzed on the basis of multireference configuration interaction electronic structure calculations with emphasis on the various avoided crossings in different regions of coordinate space. Global diabatic potential energy surfaces are constructed for the lowest four states termed X, A, B, and R. In addition, the off-diagonal potentials that couple the initially excited state B with states R and A are constructed to reflect results from additional electronic structure calculations, including the calculation of nonadiabatic coupling matrix elements. The A/X and A/R couplings are also considered, although in a less ambitious manner. The photodissociation dynamics are studied by means of trajectory surface hopping (TSH) calculations with the branching ratio between the singlet, O(1D)+O2(1Δg), and triplet, O(3P)+O2(3Σ-g), channels being the main focus. The semiclassical branching ratio agrees well with quantum mechanical results except for wavelengths close to the threshold of the singlet channel. The calculated O(1D) quantum yield is approximately 0.90-0.95 across the main part of the Hartley band, in good agreement with experimental data. TSH calculations including all four states show that transitions B→A are relatively unimportant and subsequent transitions A→X/R to the triplet channel are negligible

Selecting children for head CT following head injury

OBJECTIVE: Indicators for head CT scan defined by the 2007 National Institute for Health and Care Excellence (NICE) guidelines were analysed to identify CT uptake, influential variables and yield. DESIGN: Cross-sectional study. SETTING: Hospital inpatient units: England, Wales, Northern Ireland and the Channel Islands. PATIENTS: Children (3 years were much more likely to have CT than those <3 years (OR 2.35 (95% CI 2.08 to 2.65)). CONCLUSION: Compliance with guidelines and diagnostic yield was variable across age groups, the type of hospital and region where children were admitted. With this pattern of clinical practice the risks of both missing intracranial injury and overuse of CT are considerable

The Orbiter Stability Experiment on STS-40

The Orbiter Stability Experiment (OSE) was developed to evaluate the steadiness of the STS Orbiter as a potential platform for instrumentation that would image the Sun in its extreme ultraviolet and soft X-ray radiations. We were interested in any high frequency motions of the Orbiter's orientation due to normal operations and manned activities. Preliminary results are presented of the observations. Other than the expected slow motion of the Orbiter within the specified angular deadband of 0.1 degrees during the observations, it was found that high frequency (above 1 Hz) angular motions (jitter) were not detectable at the 0.25 arc sec detection limit of the most sensitive detector, for most of the period of observation. No high frequency motions were recorded during intervals that were identified with vernier thruster firings. However, one short interval with detectable spectral power to a frequency of 10 Hz has been found to date. It has not yet been correlated with a particular activity going on at the time. The results of the observations may also be of value in assessing perturbations to the Orbiter's micro-gravity environment produced by normal operations

State-Selective Studies of T→R, V Energy Transfer: The H+CO System

Collisional energy transfer from H atoms to CO(v=0, J≈2) has been studied at a collision energy of 1.58±0.07 eV by photolyzing H2S at 222 nm in a nozzle expansion with CO and probing the CO(v , J ) levels using tunable VUV laser-induced fluorescence. The ratio CO(v =1)/CO(v =0) is found to be 0.1±0.008. The rotational distribution of CO(v =0) peaks at J gradually; population is still observed at J \u3e45. The rotational distribution of CO(v =1) is broad and peaks near J =20. The experimental results are compared to quasiclassical trajectory calculations performed both on the H+CO surface of Bowman, Bittman, and Harding (BBH) and on the surface of Murrell and Rodriguez (MR). The experimental rotational distributions, particularly those for CO(v =1), show that the BBH surface is a better model than the MR surface. The most significant difference between the two surfaces appears to be that for energetically accessible regions of configuration space the derivative of the potential with respect to the CO distance is appreciable only in the HCO valley for the BBH surface, but is large for all H atom approaches in the MR potential. Because the H-CO geometry is bent in this valley, vibrational excitation on the BBH surface is accompanied by appreciable rotational excitation, as observed experimentally

Early vocabulary development in children with bilateral cochlear implants

BackgroundChildren with unilateral cochlear implants (CIs) may have delayed vocabulary development for an extended period after implantation. Bilateral cochlear implantation is reported to be associated with improved sound localization and enhanced speech perception in noise. This study proposed that bilateral implantation might also promote early vocabulary development. Knowledge regarding vocabulary growth and composition in children with bilateral CIs and factors associated with it may lead to improvements in the content of early speech and language intervention and family counselling. AimsTo analyse the growth of early vocabulary and its composition during the first year after CI activation and to investigate factors associated with vocabulary growth. Methods & ProceduresThe participants were 20 children with bilateral CIs (12 boys; eight girls; mean age at CI activation = 12.9 months). Vocabulary size was assessed with the Finnish version of the MacArthur Communicative Development Inventories (CDI) Infant Form and compared with normative data. Vocabulary composition was analysed in relation to vocabulary size. Growth curve modelling was implemented using a linear mixed model to analyse the effects of the following variables on early vocabulary growth: time, gender, maternal education, residual hearing with hearing aids, age at first hearing aid fitting and age at CI activation. Outcomes & ResultsDespite clear vocabulary growth over time, children with bilateral CIs lagged behind their age norms in receptive vocabulary during the first 12 months after CI activation. In expressive vocabulary, 35% of the children were able to catch up with their age norms, but 55% of the children lagged behind them. In receptive and expressive vocabularies of 1-20 words, analysis of different semantic categories indicated that social terms constituted the highest proportion. Nouns constituted the highest proportion in vocabularies of 101-400 words. The proportion of verbs remained below 20% and the proportion of function words and adjectives remained below 10% in the vocabularies of 1-400 words. There was a significant main effect of time, gender, maternal education and residual hearing with hearing aids before implantation on early receptive vocabulary growth. Time and residual hearing with hearing aids had a significant main effect also on expressive vocabulary growth. Conclusions & ImplicationsVocabulary development of children with bilateral CIs may be delayed. Thus, early vocabulary development needs to be assessed carefully in order to provide children and families with timely and targeted early intervention for vocabulary acquisition.Peer reviewe

Michaelis-Menten Relations for Complex Enzymatic Networks

All biological processes are controlled by complex systems of enzymatic chemical reactions. Although the majority of enzymatic networks have very elaborate structures, there are many experimental observations indicating that some turnover rates still follow a simple Michaelis-Menten relation with a hyperbolic dependence on a substrate concentration. The original Michaelis-Menten mechanism has been derived as a steady-state approximation for a single-pathway enzymatic chain. The validity of this mechanism for many complex enzymatic systems is surprising. To determine general conditions when this relation might be observed in experiments, enzymatic networks consisting of coupled parallel pathways are investigated theoretically. It is found that the Michaelis-Menten equation is satisfied for specific relations between chemical rates, and it also corresponds to the situation with no fluxes between parallel pathways. Our results are illustrated for simple models. The importance of the Michaelis-Menten relationship and derived criteria for single-molecule experimental studies of enzymatic processes are discussed.Comment: 10 pages, 4 figure