Bounds on the Complexity of Halfspace Intersections when the Bounded Faces have Small Dimension

We study the combinatorial complexity of D-dimensional polyhedra defined as the intersection of n halfspaces, with the property that the highest dimension of any bounded face is much smaller than D. We show that, if d is the maximum dimension of a bounded face, then the number of vertices of the polyhedron is O(n^d) and the total number of bounded faces of the polyhedron is O(n^d^2). For inputs in general position the number of bounded faces is O(n^d). For any fixed d, we show how to compute the set of all vertices, how to determine the maximum dimension of a bounded face of the polyhedron, and how to compute the set of bounded faces in polynomial time, by solving a polynomial number of linear programs

Multi-scale modeling and mechanical performance characterization of stingray skeleton-inspired tessellations

This is the author accepted manuscript. The final version is available from the publisher via the DOI in this recordSharks and rays have distinctive skeletons among vertebrate animals, consisting primarily of unmineralized cartilage wrapped in a surface tessellation of minute polygonal tiles called tesserae, linked by unmineralized collagenous fibers. The discrete combination of hard and soft tissues is hypothesized to enhance the mechanical performance of tessellated cartilage (which performs many of the same functional roles as bone) by providing either rigidity or flexibility, depending on the nature of the applied load. These mechanisms and the effect of tesserae ultrastructure on cartilage mechanics, however, have never been demonstrated in the actual tissue, nor in bio-accurate models. Here, we develop bio-inspired three-dimensional tesserae computer models, incorporating material properties and ultrastructural features from natural tessellated cartilage. The geometries of ultrastructural features were varied parametrically, and the effective modulus of whole tesserae was evaluated using finite element analysis (FEA) to determine the roles of ultrastructural features in mechanics. Whereas altering some structural features had no effect on the macroscopic in-plane modulus of tesserae, a three-fold increase in the contact surface area between two adjacent tesserae increased the effective modulus of tesserae by 6%. Modeled stress distributions suggest that tesseral ‘spokes’ (distinct hypermineralized features in tesserae) bear maximum stresses in the skeleton and serve to funnel stresses to particular populations of cells in tesserae, while spokes’ lamellated structure likely helps dissipate crack energy, making tesserae more damage-tolerant. Simulations of multi-tesseral arrays showed that maximum stresses in tension and compression are borne by different tissues, supporting hypotheses of multi-functional properties of tessellated cartilage. Further, tesseral array models showed that minor alterations to tesserae/joint shape and/or material properties can be used to tune the mechanical behavior of the whole tiled composite. Our models provide the first functional understanding of the distinct morphologies of spokes and of ‘stellate’ tesserae (a tesseral shape observed first over 150 years ago), while also being useful drivers for hypotheses of growth, mechanics, load management, and the prevention and ‘directing’ of cracks in tessellated cartilage, as well as other biological composites. Additionally, these results establish guidelines and design principles for bio-inspired, tunable tiled materials

Model-independent constraints on new physics in b --> s transitions

We provide a comprehensive model-independent analysis of rare decays involving the b --> s transition to put constraints on dimension-six Delta(F)=1 effective operators. The constraints are derived from all the available up-to-date experimental data from the B-factories, CDF and LHCb. The implications and future prospects for observables in b --> s l+l- and b --> s nu nu transitions in view of improved measurements are also investigated. The present work updates and generalises previous studies providing, at the same time, a useful tool to test the flavour structure of any theory beyond the SM.Comment: 1+39 pages, 12 figures, 3 tables. v2: minor modifications, typos corrected, references added, version to be published in JHE

Exploring New Physics in the C7-C7' plane

The Wilson coefficient C7 governing the radiative electromagnetic decays of B meson has been calculated to a very high accuracy in the Standard Model, but experimental bounds on either the magnitude or the sign of C7 are often model-dependent. In the present paper, we attempt at constraining both the magnitude and sign of C7 using a systematic approach. We consider already measured observables like the branching ratios of B \rightarrow Xs mu+ mu- and B \rightarrow Xs gamma, the isospin and CP asymmetries in B \rightarrow K* gamma, as well as AFB and FL in B \rightarrow K*l+l-. We also discuss the transverse observable AT2 which, once measured, may help to disentangle some of the scenarios considered. We explore the constraints on C7, C9, C10 as well as their chirality-flipped counterparts. Within our framework, we find that we need to extend the constraints up to 1.6 sigma to allow for the "flipped-sign solution" of C7. The SM solution for C7 exhibits a very mild tension if New Physics is allowed in dipole operators only. We provide semi-numerical expressions for all these observables as functions of the relevant Wilson coefficients at the low scale.Comment: 54 pages, 16 figures, 15 tables. Normalization factor introduced for the integrated AFB and FL in Sec.2.5 (Eq.2.35-2.38). Conclusions unchanged. Not updated in JHE

Gravitational Waves from Gravitational Collapse

Gravitational wave emission from the gravitational collapse of massive stars has been studied for more than three decades. Current state of the art numerical investigations of collapse include those that use progenitors with realistic angular momentum profiles, properly treat microphysics issues, account for general relativity, and examine non--axisymmetric effects in three dimensions. Such simulations predict that gravitational waves from various phenomena associated with gravitational collapse could be detectable with advanced ground--based and future space--based interferometric observatories.Comment: 68 pages including 13 figures; revised version accepted for publication in Living Reviews in Relativity (http://www.livingreviews.org

Predictors of low cervical cancer screening among immigrant women in Ontario, Canada

<p>Abstract</p> <p>Background</p> <p>Disparities in cervical cancer screening are known to exist in Ontario, Canada for foreign-born women. The relative importance of various barriers to screening may vary across ethnic groups. This study aimed to determine how predictors of low cervical cancer screening, reflective of sociodemographics, the health care system, and migration, varied by region of origin for Ontario's immigrant women.</p> <p>Methods</p> <p>Using a validated billing code algorithm, we determined the proportion of women who were not screened during the three-year period of 2006-2008 among 455 864 identified immigrant women living in Ontario's urban centres. We created eight identical multivariate Poisson models, stratified by eight regions of origin for immigrant women. In these models, we adjusted for various sociodemographic, health care-related and migration-related variables. We then used the resulting adjusted relative risks to calculate population-attributable fractions for each variable by region of origin.</p> <p>Results</p> <p>Region of origin was not a significant source of effect modification for lack of recent cervical cancer screening. Certain variables were significantly associated with lack of screening across all or nearly all world regions. These consisted of not being in the 35-49 year age group, residence in the lowest-income neighbourhoods, not being in a primary care patient enrolment model, a provider from the same region, and not having a female provider. For all women, the highest population-attributable risk was seen for not having a female provider, with values ranging from 16.8% [95% CI 14.6-19.1%] among women from the Middle East and North Africa to 27.4% [95% CI 26.2-28.6%] for women from East Asia and the Pacific.</p> <p>Conclusions</p> <p>To increase screening rates across immigrant groups, efforts should be made to ensure that women have access to a regular source of primary care, and ideally access to a female health professional. Efforts should also be made to increase the enrolment of immigrant women in new primary care patient enrolment models.</p

Search for Kaluza-Klein Graviton Emission in ppˉp\bar{p} Collisions at s=1.8\sqrt{s}=1.8 TeV using the Missing Energy Signature

We report on a search for direct Kaluza-Klein graviton production in a data sample of 84 ${pb}^{-1}$ of \ppb collisions at $\sqrt{s}$ = 1.8 TeV, recorded by the Collider Detector at Fermilab. We investigate the final state of large missing transverse energy and one or two high energy jets. We compare the data with the predictions from a $3+1+n$-dimensional Kaluza-Klein scenario in which gravity becomes strong at the TeV scale. At 95% confidence level (C.L.) for $n$=2, 4, and 6 we exclude an effective Planck scale below 1.0, 0.77, and 0.71 TeV, respectively.Comment: Submitted to PRL, 7 pages 4 figures/Revision includes 5 figure

Recognising and reacting to angry and happy facial expressions: a diffusion model analysis.

Researchers have reported two biases in how people recognise and respond to angry and happy facial expressions: (1) a gender-expression bias (Becker et al. in J Pers Soc Psychol, 92(2):179-190, https://doi.org/10.1037/0022-3514.92.2.179 , 2007)-faster identification of male faces as angry and female faces as happy and (2) an approach-avoidance bias-faster avoidance of people who appear angry and faster approach responses people who appear happy (Heuer et al. in Behav Res The, 45(12):2990-3001, https://doi.org/10.1016/j.brat.2007.08.010 2007; Marsh et al. in Emotion, 5(1), 119-124, https://doi.org/10.1037/1528-3542.5.1.119 , 2005; Rotteveel and Phaf in Emotion 4(2):156-172, https://doi.org/10.1037/1528-3542.4.2.156 , 2004). The aim of the current research is to gain insight into the nature of such biases by applying the drift diffusion model to the results of an approach-avoidance task. Sixty-five participants (33 female) identified faces as either happy or angry by pushing and pulling a joystick. In agreement with the original study of this effect (Solarz 1960) there were clear participant gender differences-both the approach avoidance and gender-expression biases were larger in magnitude for female compared to male participants. The diffusion model results extend recent research (Krypotos et al. in Cogn Emot 29(8):1424-1444, https://doi.org/10.1080/02699931.2014.985635 , 2015) by indicating that the gender-expression and approach-avoidance biases are mediated by separate cognitive processes

Measurement of the Bottom-Strange Meson Mixing Phase in the Full CDF Data Set

We report a measurement of the bottom-strange meson mixing phase \beta_s using the time evolution of B0_s -> J/\psi (->\mu+\mu-) \phi (-> K+ K-) decays in which the quark-flavor content of the bottom-strange meson is identified at production. This measurement uses the full data set of proton-antiproton collisions at sqrt(s)= 1.96 TeV collected by the Collider Detector experiment at the Fermilab Tevatron, corresponding to 9.6 fb-1 of integrated luminosity. We report confidence regions in the two-dimensional space of \beta_s and the B0_s decay-width difference \Delta\Gamma_s, and measure \beta_s in [-\pi/2, -1.51] U [-0.06, 0.30] U [1.26, \pi/2] at the 68% confidence level, in agreement with the standard model expectation. Assuming the standard model value of \beta_s, we also determine \Delta\Gamma_s = 0.068 +- 0.026 (stat) +- 0.009 (syst) ps-1 and the mean B0_s lifetime, \tau_s = 1.528 +- 0.019 (stat) +- 0.009 (syst) ps, which are consistent and competitive with determinations by other experiments.Comment: 8 pages, 2 figures, Phys. Rev. Lett 109, 171802 (2012

Measurement of the average time-integrated mixing probability of b-flavored hadrons produced at the Tevatron

We have measured the number of like-sign (LS) and opposite-sign (OS) lepton pairs arising from double semileptonic decays of $b$ and $\bar{b}$-hadrons, pair-produced at the Fermilab Tevatron collider. The data samples were collected with the Collider Detector at Fermilab (CDF) during the 1992-1995 collider run by triggering on the existence of $\mu \mu$ and $e \mu$ candidates in an event. The observed ratio of LS to OS dileptons leads to a measurement of the average time-integrated mixing probability of all produced $b$-flavored hadrons which decay weakly, $\bar{\chi} = 0.152 \pm 0.007$ (stat.) $\pm 0.011$ (syst.), that is significantly larger than the world average $\bar{\chi} = 0.118 \pm 0.005$.Comment: 47 pages, 10 figures, 15 tables Submitted to Phys. Rev.