A hybrid nonlinear-discriminant analysis feature projection technique

Feature set dimensionality reduction via Discriminant Analysis (DA) is one of the most sought after approaches in many applications. In this paper, a novel nonlinear DA technique is presented based on a hybrid of Artificial Neural Networks (ANN) and the Uncorrelated Linear Discriminant Analysis (ULDA). Although dimensionality reduction via ULDA can present a set of statistically uncorrelated features, but similar to the existing DA's it assumes that the original data set is linearly separable, which is not the case with most real world problems. In order to overcome this problem, a one layer feed-forward ANN trained with a Differential Evolution (DE) optimization technique is combined with ULDA to implement a nonlinear feature projection technique. This combination acts as nonlinear discriminant analysis. The proposed approach is validated on a Brain Computer Interface (BCI) problem and compared with other techniques. © 2008 Springer Berlin Heidelberg

Sun exposure behaviour, seasonal vitamin D deficiency, and relationship to bone health in adolescents

YesContext: Vitamin D is essential for bone health in adolescence, where there is rapid bone mineral content accrual. As cutaneous sun-exposure provides vitamin D, there is no recommended oral intake for UK adolescents. Objective: Assess seasonal vitamin D status and its contributors in white Caucasian adolescents, and examine bone health in those found deficient. Design: Prospective cohort study. Setting: Six schools in Greater Manchester, UK. Participants: 131 adolescents, 12–15 years. Intervention(s): Seasonal assessment of circulating 25-hydroxyvitamin D (25OHD), personal sunexposure and dietary vitamin D. Adolescents deficient (25OHD <10 ng/mL/25 nmol/L) in ≥one season underwent dual-energy X-ray absorptiometry (lumbar spine, femoral neck), with bone mineral apparent density (BMAD) correction for size, and peripheral quantitative computed tomography (distal radius) for volumetric (v)BMD. Main Outcome Measure: Serum 25OHD; BMD. Results: Mean 25OHD was highest in September: 24.1 (SD 6.9) ng/mL and lowest in January: 15.5 (5.9) ng/mL. Over the year, 16% were deficient in ≥one season and 79% insufficient (25OHD <20 ng/mL/50 nmol/L) including 28% in September. Dietary vitamin D was low year-round while personal sun-exposure was seasonal and predominantly across the school week. Holidays accounted for 17% variation in peak 25OHD (p<0.001). Nineteen adolescents underwent bone assessment, which showed low femoral neck BMAD versus matched reference data (p=0.0002), 3 with Z≤ -2.0 distal radius trabecular vBMD. Conclusions: Sun-exposure levels failed to provide adequate vitamin D, ~one-quarter adolescents insufficient even at summer-peak. Seasonal vitamin D deficiency was prevalent and those affected had low BMD. Recommendations on vitamin D acquisition are indicated in this age-group.The Bupa Foundation (Grant number TBF-M10-017)

Solar ultra-violet radiation and vitamin D synthesis in man

The solar UVB radiation incident on a horizontal surface was measured and related to more routinely recorded meteorological variabIes in a study of the UVB climatology of the English East Midlands. Exposure of individuals in this climate was monitored and related to vitamin D status. On clear days relations were found between the logarithm of UVB intensity lƛ and airmass µ,and at 304 nm where ozone amount [O3] is the dominant atmospheric attenuating factor a2 In Iƛ/aµa[03] was close to the ozone absorption coefficient for this wavelength. At longer wavelengths other attenuation processes have to be accounted for. Measurements of the waveband 300-316 nm were compared with irradiation over broader wavebands. On clear days the ratio of UVB to visible irradiance IB/IV was 4.16 cos z + x where z is the solar zenith angle and x is a coefficient which varies from day to day. Similar analysis for the full solar waveband IF showed a similar linearity of IB/IF with cos z for each day, but both slope and intercept changed between days. A relation between daily integrated totals of UVB and full solar radiation (300-3000 nm) was found, enabling UVB radiation to be estimated from measurements made with a standard meteorological pyranometer. The best estimates require daily figures for ozone concentration but an approximation may still be made using monthly mean concentrations or climatological averages. Diffuse UVB radiation was measured and found to be always greater than 0.5 global UVB. The shade-ring correction applicable in this region of the spectrum is ~ 0.01 greater than the geometric correction. Estimates of the anisotropy of UVB sky radiation gave the relative strength of the circumsolar region as 0.36 with an angular width of 0.78 radians. Polysulphone film was tested and found suitable for use as a personal dosimeter for solar UVB radiation. The UVB exposure of elderly long-stay hospital patients was monitored for a three month period and compared with that of a young healthy population. Plasma 25-hydroxyvitamin D concentrations were measured to assess vitamin D status and the change in plasma 25(OH)D resulting from skin irradiated with solar UVB was found to be 6.9 ± 0.4 ng J -1 for the elderly and + 7.3 ± 3.4 ng J-1 for the young volunteers suggesting little difference between the responses of the elderly and the young. The implication of these figures is that sunlight exposure: of a few hours per week is adequate to maintain a healthy vitamin D status

Solar ultra-violet radiation and vitamin D synthesis in man

The solar UVB radiation incident on a horizontal surface was measured and related to more routinely recorded meteorological variabIes in a study of the UVB climatology of the English East Midlands. Exposure of individuals in this climate was monitored and related to vitamin D status. On clear days relations were found between the logarithm of UVB intensity lƛ and airmass µ,and at 304 nm where ozone amount [O3] is the dominant atmospheric attenuating factor a2 In Iƛ/aµa[03] was close to the ozone absorption coefficient for this wavelength. At longer wavelengths other attenuation processes have to be accounted for. Measurements of the waveband 300-316 nm were compared with irradiation over broader wavebands. On clear days the ratio of UVB to visible irradiance IB/IV was 4.16 cos z + x where z is the solar zenith angle and x is a coefficient which varies from day to day. Similar analysis for the full solar waveband IF showed a similar linearity of IB/IF with cos z for each day, but both slope and intercept changed between days. A relation between daily integrated totals of UVB and full solar radiation (300-3000 nm) was found, enabling UVB radiation to be estimated from measurements made with a standard meteorological pyranometer. The best estimates require daily figures for ozone concentration but an approximation may still be made using monthly mean concentrations or climatological averages. Diffuse UVB radiation was measured and found to be always greater than 0.5 global UVB. The shade-ring correction applicable in this region of the spectrum is ~ 0.01 greater than the geometric correction. Estimates of the anisotropy of UVB sky radiation gave the relative strength of the circumsolar region as 0.36 with an angular width of 0.78 radians. Polysulphone film was tested and found suitable for use as a personal dosimeter for solar UVB radiation. The UVB exposure of elderly long-stay hospital patients was monitored for a three month period and compared with that of a young healthy population. Plasma 25-hydroxyvitamin D concentrations were measured to assess vitamin D status and the change in plasma 25(OH)D resulting from skin irradiated with solar UVB was found to be 6.9 ± 0.4 ng J -1 for the elderly and + 7.3 ± 3.4 ng J-1 for the young volunteers suggesting little difference between the responses of the elderly and the young. The implication of these figures is that sunlight exposure: of a few hours per week is adequate to maintain a healthy vitamin D status

Interleukin-6 and Associated Cytokine Responses to An Acute Bout of High-intensity Interval Exercise: the Effect of Exercise Intensity and Volume

Acute increases in interleukin (IL)-6 following prolonged exercise are associated with the induction of a transient anti-inflammatory state (e.g., increases in IL-10) that is partly responsible for the health benefits of regular exercise. The purposes of this study were to investigate the IL-6–related inflammatory response to high-intensity interval exercise (HIIE) and to determine the impact of exercise intensity and volume on this response. Ten participants (5 males and 5 females) completed 3 exercise bouts of contrasting intensity and volume (LOW, MOD, and HIGH). The HIGH protocol was based upon standard HIIE protocols, while the MOD and LOW protocols were designed to enable a comparison of exercise intensity and volume with a fixed duration. Inflammatory cytokine concentrations were measured in plasma (IL-6, IL-10) and also determined the level of gene expression (IL-6, IL-10, and IL-4R) in peripheral blood. The plasma IL-6 response to exercise (reported as fold changes) was significantly greater in HIGH (2.70 ± 1.51) than LOW (1.40 ± 0.32) (P = 0.04) and was also positively correlated to the mean exercise oxygen uptake (r = 0.54, P < 0.01). However, there was no change in anti-inflammatory IL-10 or IL-4R responses in plasma or at the level of gene expression. HIIE caused a significant increase in IL-6 and was greater than that seen in low-intensity exercise of the same duration. The increases in IL-6 were relatively small in magnitude, and appear to have been insufficient to induce the acute systemic anti-inflammatory effects, which are evident following longer duration exercise

Measurement of the Bottom contribution to non-photonic electron production in p+pp+p collisions at s\sqrt{s} =200 GeV

The contribution of $B$ meson decays to non-photonic electrons, which are mainly produced by the semi-leptonic decays of heavy flavor mesons, in $p+p$ collisions at $\sqrt{s} =$ 200 GeV has been measured using azimuthal correlations between non-photonic electrons and hadrons. The extracted $B$ decay contribution is approximately 50% at a transverse momentum of $p_{T} \geq 5$ GeV/$c$. These measurements constrain the nuclear modification factor for electrons from $B$ and $D$ meson decays. The result indicates that $B$ meson production in heavy ion collisions is also suppressed at high $p_{T}$.Comment: 6 pages, 4 figures, accepted by PR

Plasma Wakefield Acceleration with a Modulated Proton Bunch

The plasma wakefield amplitudes which could be achieved via the modulation of a long proton bunch are investigated. We find that in the limit of long bunches compared to the plasma wavelength, the strength of the accelerating fields is directly proportional to the number of particles in the drive bunch and inversely proportional to the square of the transverse bunch size. The scaling laws were tested and verified in detailed simulations using parameters of existing proton accelerators, and large electric fields were achieved, reaching 1 GV/m for LHC bunches. Energy gains for test electrons beyond 6 TeV were found in this case.Comment: 9 pages, 7 figure

The energy dependence of ptp_t angular correlations inferred from mean-ptp_{t} fluctuation scale dependence in heavy ion collisions at the SPS and RHIC

We present the first study of the energy dependence of $p_t$ angular correlations inferred from event-wise mean transverse momentum fluctuations in heavy ion collisions. We compare our large-acceptance measurements at CM energies $\sqrt{s_{NN}} =$ 19.6, 62.4, 130 and 200 GeV to SPS measurements at 12.3 and 17.3 GeV. $p_t$ angular correlation structure suggests that the principal source of $p_t$ correlations and fluctuations is minijets (minimum-bias parton fragments). We observe a dramatic increase in correlations and fluctuations from SPS to RHIC energies, increasing linearly with $\ln \sqrt{s_{NN}}$ from the onset of observable jet-related fluctuations near 10 GeV.Comment: 10 pages, 4 figure

Partonic flow and ϕ\phi-meson production in Au+Au collisions at sNN\sqrt{s_{NN}} = 200 GeV

We present first measurements of the $\phi$-meson elliptic flow ($v_{2}(p_{T})$) and high statistics $p_{T}$ distributions for different centralities from $\sqrt{s_{NN}}$ = 200 GeV Au+Au collisions at RHIC. In minimum bias collisions the $v_{2}$ of the $\phi$ meson is consistent with the trend observed for mesons. The ratio of the yields of the $\Omega$ to those of the $\phi$ as a function of transverse momentum is consistent with a model based on the recombination of thermal $s$ quarks up to $p_{T}\sim 4$ GeV/$c$, but disagrees at higher momenta. The nuclear modification factor ($R_{CP}$) of $\phi$ follows the trend observed in the $K^{0}_{S}$ mesons rather than in $\Lambda$ baryons, supporting baryon-meson scaling. Since $\phi$-mesons are made via coalescence of seemingly thermalized $s$ quarks in central Au+Au collisions, the observations imply hot and dense matter with partonic collectivity has been formed at RHIC.Comment: 6 pages, 4 figures, submit to PR

Star Models with Dark Energy

We have constructed star models consisting of four parts: (i) a homogeneous inner core with anisotropic pressure (ii) an infinitesimal thin shell separating the core and the envelope; (iii) an envelope of inhomogeneous density and isotropic pressure; (iv) an infinitesimal thin shell matching the envelope boundary and the exterior Schwarzschild spacetime. We have analyzed all the energy conditions for the core, envelope and the two thin shells. We have found that, in order to have static solutions, at least one of the regions must be constituted by dark energy. The results show that there is no physical reason to have a superior limit for the mass of these objects but for the ratio of mass and radius.Comment: 20 pages, 1 figure, references and some comments added, typos corrected, in press GR