Twin building lattices do not have asymptotic cut-points

We show that twin building lattices have linear divergence, which implies that all asymptotic cones are without cut-points.Comment: 7 page

Non-exercise equations to estimate fitness in white European and South Asian men

Cardiorespiratory fitness is a strong, independent predictor of health, whether it is measured in an exercise test or estimated in an equation. The purpose of this study was to develop and validate equations to estimate fitness in middle-aged white European and South Asian men.Multiple linear regression models (n=168, including 83 white European and 85 South Asian men) were created using variables that are thought to be important in predicting fitness (VO2 max, mL⋅kg⋅min): age (years); BMI (kg·m); resting heart rate (beats⋅min); smoking status (0=never smoked, 1=ex or current smoker); physical activity expressed as quintiles (0=quintile 1, 1=quintile 2, 2=quintile 3, 3=quintile 4, 4=quintile 5), categories of moderate- to vigorous-intensity physical activity (0=<75 min⋅wk, 1=75-150 min⋅wk, 2=>150-225 min⋅wk, 3=>225-300 min⋅wk, 4=>300 min⋅wk), or minutes of moderate- to vigorous-intensity physical activity (min⋅wk); and, ethnicity (0=South Asian, 1=white). The leave-one-out-cross-validation procedure was used to assess the generalizability and the bootstrap and jackknife resampling techniques were used to estimate the variance and bias of the models.Around 70% of the variance in fitness was explained in models with an ethnicity variable, such as: VO2 max = 77.409 - (age*0.374) - (BMI*0.906) - (ex or current smoker*1.976) + (physical activity quintile coefficient) - (resting heart rate*0.066) + (white ethnicity*8.032), where physical activity quintile 1 is 1, 2 is 1.127, 3 is 1.869, 4 is 3.793, and 5 is 3.029. Only around 50% of the variance was explained in models without an ethnicity variable. All models with an ethnicity variable were generalizable and had low variance and bias.These data demonstrate the importance of incorporating ethnicity in non-exercise equations to estimate cardiorespiratory fitness in multi-ethnic populations

Phase-space analysis of interacting phantom cosmology

We perform a detailed phase-space analysis of various phantom cosmological models, where the dark energy sector interacts with the dark matter one. We examine whether there exist late-time scaling attractors, corresponding to an accelerating universe and possessing dark energy and dark matter densities of the same order. We find that all the examined models, although accepting stable late-time accelerated solutions, cannot alleviate the coincidence problem, unless one imposes a form of fine-tuning in the model parameters. It seems that interacting phantom cosmology cannot fulfill the basic requirement that led to its construction.Comment: 6 figures, use revtex, v2: minor corrections, references added, accepted for publication in JCA

Outcome of Infertility Consultations in a tropical tertiary health institution in Nigeria

Aim: To examine the outcome of gynaecological consultations for infertility in a tropical Teaching Health facility.Material & Methods: This is a cross-sectional study of infertility cases seen at the Bowen University Teaching Hospital, Ogbomoso over a year (16 October, 2010 to 15 October, 2011). The patients were followed up for twelve months thereafter. Data collection was done using a designed profoma. All patients coming for gynaecological consultations because of infertility within the study period were included in the study after giving their informed consents. Patient information recorded in the profoma included age, parity, educational status, occupation, duration of infertility, investigations, modality of treatment and treatment outcome. Outcome was measured by the number of live births amongst treated patients.Results: A total of 195 patients presented for gynaecological consultations during the one year period; infertility was one of the commonest reasons for gynaecological consultation, accounting for 38.5% (75) of the cases. Tubal factor, 25(33.5%) was the commonest etiological cause. The treatment modality involved myomectomy (20, 26.6%), ovulation induction (20, 26.6%), laparoscopic adhesiolysis (8, 10.7%) and tubal surgery (5, 6.7%). Treatment of infertility resulted in 10 (13.3%) live births, with ovulation induction giving the highest percentage of live births (5, 50%).Conclusion: The outcome of treatment of infertility is poor. Therefore, establishing a standard assisted reproductive technology (ART) unit will be of immense value in improving the outcome.Keywords: Infertility, consultation, outcom

RADIOACTIVITY CONCENTRATION AND DOSE ASSESSMENT OF SOIL SAMPLES IN CEMENT FACTORY AND ENVIRONS IN OGUN STATE, NIGERIA

The main natural radioactive materials that contribute externally and internally to man and his environs are radionuclides emanating from gamma series of 238U, 232Th, as well as 40K isotope, alpha and beta sources. Also, human activities such as mining and milling of uranium and phosphate, tobacco smoking, oil exploration, air transportation, coal-fired power station, and so on can trigger The technologically Enhanced Naturally Occurring Radioactive Materials (TENORMs). It is imperative to monitor the terrestrial background radiation of radionuclides emanating from these sources in order maintain a safe environment for humans. This study measured the activity concentration of 238U, 40K and 232Th in soil samples from cement factory and environs using the NaI(TI) detector, in three zones in Ogun State, Nigeria. The activity concentrations obtained for the three zones are in the order 238U < 232Th < 40K respectively. The radiological parameters estimated from the activity measured were all within the recommended permissive limit except for the annual gonadal doses from the cement factory and its environs, which are higher than the global standard by the factors of 1.03 and 1.07 respectively. This study therefore concludes that people living and working in these areas might be exposed to high radiation burden as a result of cumulative effect of the emission from the factory

Horava-Lifshitz Dark Energy

We formulate Horava-Lifshitz cosmology with an additional scalar field that leads to an effective dark energy sector. We find that, due to the inherited features from the gravitational background, Horava-Lifshitz dark energy naturally presents very interesting behaviors, possessing a varying equation-of-state parameter, exhibiting phantom behavior and allowing for a realization of the phantom divide crossing. In addition, Horava-Lifshitz dark energy guarantees for a bounce at small scale factors and it may trigger the turnaround at large scale factors, leading naturally to cyclic cosmology.Comment: 17 pages, no figures, version published at EJP

Rank rigidity for CAT(0) cube complexes

We prove that any group acting essentially without a fixed point at infinity on an irreducible finite-dimensional CAT(0) cube complex contains a rank one isometry. This implies that the Rank Rigidity Conjecture holds for CAT(0) cube complexes. We derive a number of other consequences for CAT(0) cube complexes, including a purely geometric proof of the Tits Alternative, an existence result for regular elements in (possibly non-uniform) lattices acting on cube complexes, and a characterization of products of trees in terms of bounded cohomology.Comment: 39 pages, 4 figures. Revised version according to referee repor

Observational constraints on holographic dark energy with varying gravitational constant

We use observational data from Type Ia Supernovae (SN), Baryon Acoustic Oscillations (BAO), Cosmic Microwave Background (CMB) and observational Hubble data (OHD), and the Markov Chain Monte Carlo (MCMC) method, to constrain the cosmological scenario of holographic dark energy with varying gravitational constant. We consider both flat and non-flat background geometry, and we present the corresponding constraints and contour-plots of the model parameters. We conclude that the scenario is compatible with observations. In 1$\sigma$ we find $\Omega_{\Lambda0}=0.72^{+0.03}_{-0.03}$, $\Omega_{k0}=-0.0013^{+0.0130}_{-0.0040}$, $c=0.80^{+0.19}_{-0.14}$ and $\Delta_G\equiv G'/G=-0.0025^{+0.0080}_{-0.0050}$, while for the present value of the dark energy equation-of-state parameter we obtain $w_0=-1.04^{+0.15}_{-0.20}$.Comment: 12 pages, 2 figures, version published in JCA

Penrose Limits of Orbifolds and Orientifolds

We study the Penrose limit of various AdS_p X S^q orbifolds. The limiting spaces are waves with parallel rays and singular wave fronts. In particular, we consider the orbifolds AdS_3 X S^3/\Gamma, AdS_5 X S^5/\Gamma and AdS_{4,7} X S^{7,4}/\Gamma where \Gamma acts on the sphere and/or the AdS factor. In the pp-wave limit, the wave fronts are the orbifolds C^2/\Gamma, C^4/\Gamma and R XC^4/\Gamma, respectively. When desingularization is possible, we get asymptotically locally pp-wave backgrounds (ALpp). The Penrose limit of orientifolds are also discussed. In the AdS_5 X RP^5 case, the limiting singularity can be resolved by an Eguchi-Hanson gravitational instanton. The pp-wave limit of D3-branes near singularities in F-theory is also presented. Finally, we give the embedding of D-dimensional pp-waves in flat M^{2,D} space.Comment: 20 pages, references adde

On the distortion of twin building lattices

We show that twin building lattices are undistorted in their ambient group; equivalently, the orbit map of the lattice to the product of the associated twin buildings is a quasi-isometric embedding. As a consequence, we provide an estimate of the quasi-flat rank of these lattices, which implies that there are infinitely many quasi-isometry classes of finitely presented simple groups. In an appendix, we describe how non-distortion of lattices is related to the integrability of the structural cocycle