2,399 research outputs found
Pleosporales
One hundred and five generic types of Pleosporales are described and illustrated. A brief introduction and detailed history with short notes on morphology, molecular phylogeny as well as a general conclusion of each genus are provided. For those genera where the type or a representative specimen is unavailable, a brief note is given. Altogether 174 genera of Pleosporales are treated. Phaeotrichaceae as well as Kriegeriella, Zeuctomorpha and Muroia are excluded from Pleosporales. Based on the multigene phylogenetic analysis, the suborder Massarineae is emended to accommodate five families, viz. Lentitheciaceae, Massarinaceae, Montagnulaceae, Morosphaeriaceae and Trematosphaeriaceae
Low Scale Flavor Gauge Symmetries
We study the possibility of gauging the Standard Model flavor group. Anomaly
cancellation leads to the addition of fermions whose mass is inversely
proportional to the known fermion masses. In this case all flavor violating
effects turn out to be controlled roughly by the Standard Model Yukawa,
suppressing transitions for the light generations. Due to the inverted
hierarchy the scale of new gauge flavor bosons could be as low as the
electroweak scale without violating any existing bound but accessible at the
Tevatron and the LHC. The mechanism of flavor protection potentially provides
an alternative to Minimal Flavor Violation, with flavor violating effects
suppressed by hierarchy of scales rather than couplings.Comment: 24 pages + appendices; v2) Refs. added and numerical examples
improved. Results unchanged; v3) small typos in appendix B correcte
Gauged Flavor Group with Left-Right Symmetry
We construct an anomaly-free extension of the left-right symmetric model,
where the maximal flavor group is gauged and anomaly cancellation is guaranteed
by adding new vectorlike fermion states. We address the question of the lowest
allowed flavor symmetry scale consistent with data. Because of the mechanism
recently pointed out by Grinstein et al. tree-level flavor changing neutral
currents turn out to play a very weak constraining role. The same occurs, in
our model, for electroweak precision observables. The main constraint turns out
to come from WR-mediated flavor changing neutral current box diagrams,
primarily K - Kbar mixing. In the case where discrete parity symmetry is
present at the TeV scale, this constraint implies lower bounds on the mass of
vectorlike fermions and flavor bosons of 5 and 10 TeV respectively. However,
these limits are weakened under the condition that only SU(2)_R x U(1)_{B-L} is
restored at the TeV scale, but not parity. For example, assuming the SU(2)
gauge couplings in the ratio gR/gL approx 0.7 allows the above limits to go
down by half for both vectorlike fermions and flavor bosons. Our model provides
a framework for accommodating neutrino masses and, in the parity symmetric
case, provides a solution to the strong CP problem. The bound on the lepton
flavor gauging scale is somewhat stronger, because of Big Bang Nucleosynthesis
constraints. We argue, however, that the applicability of these constraints
depends on the mechanism at work for the generation of neutrino masses.Comment: 1+23 pages, 1 table, 5 figures. v3: some more textual fixes (main
change: discussion of Lepton Flavor Violating observables rephrased). Matches
journal versio
Composite Leptoquarks at the LHC
If electroweak symmetry breaking arises via strongly-coupled physics, the
observed suppression of flavour-changing processes suggests that fermion masses
should arise via mixing of elementary fermions with composite fermions of the
strong sector. The strong sector then carries colour charge, and may contain
composite leptoquark states, arising either as TeV scale resonances, or even as
light, pseudo-Nambu-Goldstone bosons. The latter, since they are coupled to
colour, get a mass of the order of several hundred GeV, beyond the reach of
current searches at the Tevatron. The same generic mechanism that suppresses
flavour-changing processes suppresses leptoquark-mediated rare processes,
making it conceivable that the many stringent constraints may be evaded. The
leptoquarks couple predominantly to third-generation quarks and leptons, and
the prospects for discovery at LHC appear to be good. As an illustration, a
model based on the Pati-Salam symmetry is described, and its embedding in
models with a larger symmetry incorporating unification of gauge couplings,
which provide additional motivation for leptoquark states at or below the TeV
scale, is discussed.Comment: 10 pp, version to appear in JHE
A bi-directional relationship between obesity and health-related quality of life : evidence from the longitudinal AusDiab study
Objective: To assess the prospective relationship between obesity and health-related quality of life, including a novel assessment of the impact of health-related quality of life on weight gain.Design and setting: Longitudinal, national, population-based Australian Diabetes, Obesity and Lifestyle (AusDiab) study, with surveys conducted in 1999/2000 and 2004/2005.Participants: A total of 5985 men and women aged 25 years at study entry.Main outcome measure(s): At both time points, height, weight and waist circumference were measured and self-report data on health-related quality of life from the SF-36 questionnaire were obtained. Cross-sectional and bi-directional, prospective associations between obesity categories and health-related quality of life were assessed.Results: Higher body mass index (BMI) at baseline was associated with deterioration in health-related quality of life over 5 years for seven of the eight health-related quality of life domains in women (all P0.01, with the exception of mental health, P>0.05), and six out of eight in men (all P<0.05, with the exception of role-emotional, P=0.055, and mental health, P>0.05). Each of the quality-of-life domains related to mental health as well as the mental component summary were inversely associated with BMI change (all P<0.0001 for women and P0.01 for men), with the exception of vitality, which was significant in women only (P=0.008). For the physical domains, change in BMI was inversely associated with baseline general health in women only (P=0.023).Conclusions: Obesity was associated with a deterioration in health-related quality of life (including both physical and mental health domains) in this cohort of Australian adults followed over 5 years. Health-related quality of life was also a predictor of weight gain over 5 years, indicating a bi-directional association between obesity and health-related quality of life. The identification of those with poor health-related quality of life may be important in assessing the risk of future weight gain, and a focus on health-related quality of life may be beneficial in weight management strategies.<br /
The Impact of Flavour Changing Neutral Gauge Bosons on B->X_s gamma
The branching ratio of the rare decay B->X_s gamma provides potentially
strong constraints on models beyond the Standard Model. Considering a general
scenario with new heavy neutral gauge bosons, present in particular in Z' and
gauge flavour models, we point out two new contributions to the B->X_s gamma
decay. The first one originates from one-loop diagrams mediated by gauge bosons
and heavy exotic quarks with electric charge -1/3. The second contribution
stems from the QCD mixing of neutral current-current operators generated by
heavy neutral gauge bosons and the dipole operators responsible for the B->X_s
gamma decay. The latter mixing is calculated here for the first time. We
discuss general sum rules which have to be satisfied in any model of this type.
We emphasise that the neutral gauge bosons in question could also significantly
affect other fermion radiative decays as well as non-leptonic two-body B
decays, epsilon'/epsilon, anomalous (g-2)_mu and electric dipole moments.Comment: 31 pages, 5 figures; version published on JHEP; added magic QCD
numbers for flavour-violating Z gauge boson contribution to B -> X_s gamm
Sphalerons and the Electroweak Phase Transition in Models with Higher Scalar Representations
In this work we investigate the sphaleron solution in a
gauge theory, which also encompasses the Standard Model, with higher scalar
representation(s) (). We show that the field profiles
describing the sphaleron in higher scalar multiplet, have similar trends like
the doublet case with respect to the radial distance. We compute the sphaleron
energy and find that it scales linearly with the vacuum expectation value of
the scalar field and its slope depends on the representation. We also
investigate the effect of gauge field and find that it is small for the
physical value of the mixing angle, and resembles the case for the
doublet. For higher representations, we show that the criterion for strong
first order phase transition, , is relaxed with respect to
the doublet case, i.e. .Comment: 20 pages, 5 figures & 1 table, published versio
Chronic non-specific low back pain - sub-groups or a single mechanism?
Copyright 2008 Wand and O'Connell; licensee BioMed Central Ltd.
This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0),
which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.Background: Low back pain is a substantial health problem and has subsequently attracted a
considerable amount of research. Clinical trials evaluating the efficacy of a variety of interventions
for chronic non-specific low back pain indicate limited effectiveness for most commonly applied
interventions and approaches.
Discussion: Many clinicians challenge the results of clinical trials as they feel that this lack of
effectiveness is at odds with their clinical experience of managing patients with back pain. A
common explanation for this discrepancy is the perceived heterogeneity of patients with chronic
non-specific low back pain. It is felt that the effects of treatment may be diluted by the application
of a single intervention to a complex, heterogeneous group with diverse treatment needs. This
argument presupposes that current treatment is effective when applied to the correct patient.
An alternative perspective is that the clinical trials are correct and current treatments have limited
efficacy. Preoccupation with sub-grouping may stifle engagement with this view and it is important
that the sub-grouping paradigm is closely examined. This paper argues that there are numerous
problems with the sub-grouping approach and that it may not be an important reason for the
disappointing results of clinical trials. We propose instead that current treatment may be ineffective
because it has been misdirected. Recent evidence that demonstrates changes within the brain in
chronic low back pain sufferers raises the possibility that persistent back pain may be a problem of
cortical reorganisation and degeneration. This perspective offers interesting insights into the
chronic low back pain experience and suggests alternative models of intervention.
Summary: The disappointing results of clinical research are commonly explained by the failure of
researchers to adequately attend to sub-grouping of the chronic non-specific low back pain
population. Alternatively, current approaches may be ineffective and clinicians and researchers may
need to radically rethink the nature of the problem and how it should best be managed
Measurement of the inclusive and dijet cross-sections of b-jets in pp collisions at sqrt(s) = 7 TeV with the ATLAS detector
The inclusive and dijet production cross-sections have been measured for jets
containing b-hadrons (b-jets) in proton-proton collisions at a centre-of-mass
energy of sqrt(s) = 7 TeV, using the ATLAS detector at the LHC. The
measurements use data corresponding to an integrated luminosity of 34 pb^-1.
The b-jets are identified using either a lifetime-based method, where secondary
decay vertices of b-hadrons in jets are reconstructed using information from
the tracking detectors, or a muon-based method where the presence of a muon is
used to identify semileptonic decays of b-hadrons inside jets. The inclusive
b-jet cross-section is measured as a function of transverse momentum in the
range 20 < pT < 400 GeV and rapidity in the range |y| < 2.1. The bbbar-dijet
cross-section is measured as a function of the dijet invariant mass in the
range 110 < m_jj < 760 GeV, the azimuthal angle difference between the two jets
and the angular variable chi in two dijet mass regions. The results are
compared with next-to-leading-order QCD predictions. Good agreement is observed
between the measured cross-sections and the predictions obtained using POWHEG +
Pythia. MC@NLO + Herwig shows good agreement with the measured bbbar-dijet
cross-section. However, it does not reproduce the measured inclusive
cross-section well, particularly for central b-jets with large transverse
momenta.Comment: 10 pages plus author list (21 pages total), 8 figures, 1 table, final
version published in European Physical Journal
What we talk about when we talk about "global mindset": managerial cognition in multinational corporations
Recent developments in the global economy and in multinational corporations have placed significant emphasis on the cognitive orientations of managers, giving rise to a number of concepts such as “global mindset” that are presumed to be associated with the effective management of multinational corporations (MNCs). This paper reviews the literature on global mindset and clarifies some of the conceptual confusion surrounding the construct. We identify common themes across writers, suggesting that the majority of studies fall into one of three research perspectives: cultural, strategic, and multidimensional. We also identify two constructs from the social sciences that underlie the perspectives found in the literature: cosmopolitanism and cognitive complexity and use these two constructs to develop an integrative theoretical framework of global mindset. We then provide a critical assessment of the field of global mindset and suggest directions for future theoretical and empirical research
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