951 research outputs found
Ordered groupoids and the holomorph of an inverse semigroup
We present a construction for the holomorph of an inverse semigroup, derived
from the cartesian closed structure of the category of ordered groupoids. We
compare the holomorph with the monoid of mappings that preserve the ternary
heap operation on an inverse semigroup: for groups these two constructions
coincide. We present detailed calculations for semilattices of groups and for
the polycyclic monoids.Comment: 16 page
Cardiac magnetic resonance imaging in stable ischaemic heart disease
Cardiac magnetic resonance imaging (CMR) is a new robust versatile non-invasive imaging technique that can detect global and regional myocardial dysfunction, presence of myocardial ischaemia and myocardial scar tissue in one imaging session without radiation, with superb spatial and temporal resolution, inherited three-dimensional data collection and with relatively safe contrast material. The reproducibility of CMR is high which makes it possible to use this technique for serial assessment to evaluate the effect of revascularisation therapy in patients with ischaemic heart disease
The cost of promiscuity: sexual transmission of Nosema microsporidian parasites in polyandrous honey bees
Multiple mating (and insemination) by females with different males, polyandry, is widespread across animals, due to material and/or genetic benefits for females. It reaches particularly high levels in some social insects, in which queens can produce significantly fitter colonies by being polyandrous. It is therefore a paradox that two thirds of eusocial hymenopteran insects appear to be exclusively monandrous, in spite of the fitness benefits that polyandry could provide. One possible cost of polyandry could be sexually transmitted parasites, but evidence for these in social insects is extremely limited. Here we show that two different species of Nosema microsporidian parasites can transmit sexually in the honey bee Apis mellifera. Honey bee males that are infected by the parasite have Nosema spores in their semen, and queens artificially inseminated with either Nosema spores or the semen of Nosema-infected males became infected by the parasite. The emergent and more virulent N. ceranae achieved much higher rates of infection following insemination than did N. apis. The results provide the first quantitative evidence of a sexually transmitted disease (STD) in social insects, indicating that STDs may represent a potential cost of polyandry in social insects
A Standardised Procedure for Evaluating Creative Systems: Computational Creativity Evaluation Based on What it is to be Creative
Computational creativity is a flourishing research area, with a variety of creative systems being produced and developed. Creativity evaluation has not kept pace with system development with an evident lack of systematic evaluation of the creativity of these systems in the literature. This is partially due to difficulties in defining what it means for a computer to be creative; indeed, there is no consensus on this for human creativity, let alone its computational equivalent. This paper proposes a Standardised Procedure for Evaluating Creative Systems (SPECS). SPECS is a three-step process: stating what it means for a particular computational system to be creative, deriving and performing tests based on these statements. To assist this process, the paper offers a collection of key components of creativity, identified empirically from discussions of human and computational creativity. Using this approach, the SPECS methodology is demonstrated through a comparative case study evaluating computational creativity systems that improvise music
Second trimester inflammatory and metabolic markers in women delivering preterm with and without preeclampsia.
ObjectiveInflammatory and metabolic pathways are implicated in preterm birth and preeclampsia. However, studies rarely compare second trimester inflammatory and metabolic markers between women who deliver preterm with and without preeclampsia.Study designA sample of 129 women (43 with preeclampsia) with preterm delivery was obtained from an existing population-based birth cohort. Banked second trimester serum samples were assayed for 267 inflammatory and metabolic markers. Backwards-stepwise logistic regression models were used to calculate odds ratios.ResultsHigher 5-α-pregnan-3β,20α-diol disulfate, and lower 1-linoleoylglycerophosphoethanolamine and octadecanedioate, predicted increased odds of preeclampsia.ConclusionsAmong women with preterm births, those who developed preeclampsia differed with respect metabolic markers. These findings point to potential etiologic underpinnings for preeclampsia as a precursor to preterm birth
Yukawa Unification and the Superpartner Mass Scale
Naturalness in supersymmetry (SUSY) is under siege by increasingly stringent
LHC constraints, but natural electroweak symmetry breaking still remains the
most powerful motivation for superpartner masses within experimental reach. If
naturalness is the wrong criterion then what determines the mass scale of the
superpartners? We motivate supersymmetry by (1) gauge coupling unification, (2)
dark matter, and (3) precision b-tau Yukawa unification. We show that for an
LSP that is a bino-Higgsino admixture, these three requirements lead to an
upper-bound on the stop and sbottom masses in the several TeV regime because
the threshold correction to the bottom mass at the superpartner scale is
required to have a particular size. For tan beta about 50, which is needed for
t-b-tau unification, the stops must be lighter than 2.8 TeV when A_t has the
opposite sign of the gluino mass, as is favored by renormalization group
scaling. For lower values of tan beta, the top and bottom squarks must be even
lighter. Yukawa unification plus dark matter implies that superpartners are
likely in reach of the LHC, after the upgrade to 14 (or 13) TeV, independent of
any considerations of naturalness. We present a model-independent, bottom-up
analysis of the SUSY parameter space that is simultaneously consistent with
Yukawa unification and the hint for m_h = 125 GeV. We study the flavor and dark
matter phenomenology that accompanies this Yukawa unification. A large portion
of the parameter space predicts that the branching fraction for B_s to mu^+
mu^- will be observed to be significantly lower than the SM value.Comment: 34 pages plus appendices, 20 figure
Determinants of participation in a web-based health risk assessment and consequences for health promotion programs
Background: The health risk assessment (HRA) is a type of health promotion program frequently offered at the workplace. Insight into the underlying determinants of participation is needed to evaluate and implement these interventions. Objective: To analyze whether individual characteristics including demographics, health behavior, self-rated health, and work-related factors are associated with participation and nonparticipation in a Web-based HRA. Methods: Determinants of participation and nonparticipation were investigated in a cross-sectional study among individuals employed at five Dutch organizations. Multivariate logistic regression was performed to identify determinants of participation and nonparticipation in the HRA after controlling for organization and all other variables. Results: Of the 8431 employees who were invited, 31.9% (2686/8431) enrolled in the HRA. The online questionnaire was completed by 27.2% (1564/5745) of the nonparticipants. Determinants of participation were some periods of stress at home or work in the preceding year (OR 1.62, 95% CI 1.08-2.42), a decreasing number of weekdays on which at least 30 minutes were spent on moderate to vigorous physical activity (ORdayPA0.84, 95% CI 0.79-0.90), and increasing alcohol consumption. Determinants of nonparticipation were less-than-positive self-rated health (poor/very poor vs very good, OR 0.25, 95% CI 0.08-0.81) and tobacco use (at least weekly vs none, OR 0.65, 95% CI 0.46-0.90). Conclusions: This study showed that with regard to isolated health behaviors (insufficient physical activity, excess alcohol consumption, and stress), those who could benefit most from the HRA were more likely to participate. However, tobacco users and those who rate
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