Newly discovered brown dwarfs not seen in microlensing time scale frequency distribution?

The 2-Micron All Sky Survey (2MASS) (Skrutskie et al. 1997) and the DEep Near Infrared Survey of the southern sky (DENIS) (Epchtein et al. 1997) have revealed a heretofore unknown population of free brown dwarfs that has extended the local mass function down to as small as 0.01M_sun (Reid et al. 1999). If this local proportion of brown dwarfs extends throughout the Galaxy---in particular in the Galactic bulge---one expects an increase in the predicted fraction of short time scale microlensing events in directions toward the Galactic bulge. Zhao et al.(1996) have indicated that a mass function with 30-60% of the lens mass in brown dwarfs is not consistent with empirical microlensing data. Here we show that even the much lower mass fraction (~ 10%) of brown dwarfs inferred from the new discoveries appears inconsistent with the data. The added brown dwarfs do indeed increase the expected number of short time scale events, but they appear to drive the peak in the time scale frequency distribution to time scales smaller than that observed, and do not otherwise match the observed distribution. A reasonably good match to the empirical data (Alcock et al. 1996) is obtained by increasing the fraction of stars in the range 0.08<m<0.7M_sun considerably above that deduced from several star counts. However, all inferences from microlensing about the appropriate stellar mass function must be qualified by the meagerness of the microlensing data and the uncertainties in the Galactic model.Comment: 5 pages, 1 figure. PS file using aas2pp4.sty. To appear in ApJ Letter

Probability of Detecting a Planetary Companion during a Microlensing Event

The probability of detecting a planetary companion of a lensing star during a microlensing event toward the Galactic center, averaged over all relevant event and galactic parameters, when the planet-star mass ratio $q=0.001$ has a maximum exceeding 10% at an orbit semimajor axis $a$ near 1.5 AU for a uniform distribution of impact parameters. The maximum probability is raised to more than 20% for a distribution of source-lens impact parameters that is determined by the efficiency of event detection. The averaging procedures are carefully defined, and they determinine the dependence of the detection probabilities on several properties of the Galaxy. The probabilities scale approximately as $\sqrt{q}$. A planet is assumed detectable if the perturbation of the single lens light curve exceeds $2/(S/N)$ for at least 20 consecutive photometric points sometime during the event. Two meter telescopes with 60 second integrations in I-band with high time resolution photometry throughout the duration of an ongoing event are assumed. The probabilities are derived as a function of $a$, where they remain significant for $0.6<a<10$ AU. Dependence of the detection probabilities on the lens mass function, luminosity function of the source stars as modified by extinction, distribution of source-lens impact parameters, and the line of sight to the source are also determined, and the probabilities are averaged over the distribution of the projected planet position, the lens mass function, the distribution of impact parameters, the lens and source distances as weighted by their distributions along the line of sight and over the $I$-band apparent luminosity function of the sources. The extraction of the probabilility as a function of $a$ for a particular $q$ from empirical data is indicated.Comment: 32 pages, 20 figures, In Press, ApJ, Latex format with aas2pp4 forma

Exploring the rationale of enlightened shareholder value in the realm of UK company law – the path dependence perspective

Despite conventional beliefs in the predominance of shareholder value, a broader agenda of stakeholder consideration has been advocated in the UK by the recently-introduced ESV principle – the overriding corporate objective in the new company law regime. In this paper, the efficiency of this principle in terms of stakeholder enhancement is challenged through an interdisciplinary analysis. Through a critical review of the ESV principle, it is discovered that stakeholder enhancement practices in the context of the 2006 company law regime are still for the fundamental goal of shareholder value maximisation, and that their enlightened impact has been fairly limited in practice. Furthermore, by revisiting the interrelationships between UK economic, political and cultural factors with the predominance objective of shareholder value maximisation in the Companies Act 2006, it is discovered that the enlightened effect of this new approach in the company law regime is in fact impeded by strong, persistent forces deriving from shareholder-oriented particulars. Providing insight into the future direction of corporate governance practice, the paper concludes the rationale behind the shareholder-oriented ESV principle, and further suggests the continuing predominance of shareholder value in UK corporate governance

Multi-view Regularized Gaussian Processes

Gaussian processes (GPs) have been proven to be powerful tools in various areas of machine learning. However, there are very few applications of GPs in the scenario of multi-view learning. In this paper, we present a new GP model for multi-view learning. Unlike existing methods, it combines multiple views by regularizing marginal likelihood with the consistency among the posterior distributions of latent functions from different views. Moreover, we give a general point selection scheme for multi-view learning and improve the proposed model by this criterion. Experimental results on multiple real world data sets have verified the effectiveness of the proposed model and witnessed the performance improvement through employing this novel point selection scheme

Estimating the characteristics of runoff inflow into Lake Gojal in ungauged, highly glacierized upper Hunza River Basin, Pakistan

Motivated by the potential flood outburst of Lake Gojal in the ungauged highly glacierized (27%) upper Hunza River Basin (HRB) in Pakistan that was dammed by a massive landslide on 4 January 2010, we attempt to analyze the characteristics of water inflow to the lake employing remote sensing data, two hydrological models, and sparsely observed data. One of the models (Model I) is a monthly degree-day model, while another (Model II) is the variable infiltration capacity (VIC) model. The mixture of glacier runoff output from Model I and runoff over unglacierized areas calculated by Model II has a similar seasonal variation pattern as that estimated from data recorded at a downstream station. This suggests that glacier runoff is the main source (87%) of runoff inflow into the lake. A sensitivity analysis suggests that the water inflow to the lake is highly sensitive to an increase in air temperature. Runoff in May is predicted to sharply increase by 15% to more than two-fold if the air temperature increases by 1 to 7, but it is predicted to increase only from 9% to 34% if the precipitation increases by 10% to 40%. The results suggested that the water inflow into Lake Gojal will not sharply rise even if there is heavy rain, and it needs to be in caution if the air temperature sharply increases. Analysis on long-term air temperature record indicates that the water inflow into the lake in May 2010 was probably less than average owing to the relatively low air temperature. Consequently, the flood outburst did not occur before the completion of the spillway on 29 May 2010. © 2013 China University of Geosciences and Springer-Verlag Berlin Heidelberg

Breakdown of QCD Factorization for P-Wave Quarkonium Production at Low Transverse Momentum

Quarkonium production at low transverse momentum in hadron collisions can be used to extract Transverse-Momentum-Dependent(TMD) gluon distribution functions, if TMD factorization holds there. We show that TMD factorization for the case of P-wave quarkonium with $J^{PC}=0^{++}, 2^{++}$ holds at one-loop level, but is violated beyond one-loop level. TMD factorization for other P-wave quarkonium is also violated already at one-loop.Comment: Published version in Physics Letters B (2014), pp. 103-10

Transverse Momentum Dependent Factorization for Quarkonium Production at Low Transverse Momentum

Quarkonium production in hadron collisions at low transverse momentum $q_\perp \ll M$ with $M$ as the quarkonium mass can be used for probing transverse momentum dependent (TMD) gluon distributions. For this purpose, one needs to establish the TMD factorization for the process. We examine the factorization at the one-loop level for the production of $\eta_c$ or $\eta_b$. The perturbative coefficient in the factorization is determined at one-loop accuracy. Comparing the factorization derived at tree level and that beyond the tree level, a soft factor is, in general, needed to completely cancel soft divergences. We have also discussed possible complications of TMD factorization of p-wave quarkonium production.Comment: Title changed in the journal, published versio

Effect of oxygen stoichiometry on T(sub c) of Bi-based superconductors

The role of oxygen stoichiometry on T(sub c) is relatively well established on La2CuO(4+x) and the YBa2Cu3O(7-x) (123) superconductors, as compared to the Bi-based superconductors. Results are presented of investigations on the effects of oxygen stoichiometry on the transition temperature T(sub c) of Bi2Sr2CaCu2O(8+x) (2212 phase), and Pb-doped Bi2Sr2Ca2Cu3O(10+X) (2223 phase). It is shown that the effects of oxygen stoichiometry on T(sub c) of these two phases are very different. These results may be helpful in understanding the mechanism of superconductivity in the Bi-based superconductors