278 research outputs found
D-brane Inspired Fermion Mass Textures
In this paper, the issues of the quark mass hierarchies and the Cabbibo
Kobayashi Maskawa mixing are analyzed in a class of intersecting D-brane
configurations with Standard Model gauge symmetry. The relevant mass matrices
are constructed taking into account the constraints imposed by extra abelian
symmetries and anomaly cancelation conditions. Possible mass generating
mechanisms including perturbative as well as non-perturbative effects are
discussed and specific patterns of mass textures are found characterized by the
hierarchies of the scales where the various sources contribute. It is argued
that the Cholesky decomposition of the mass matrices is the most appropriate
way to determine the properties of these fermion mass patterns, while the
associated triangular mass matrix form provides a unified description of all
phenomenologically equivalent symmetric and non-symmetric mass matrices. An
elegant analytic formula is derived for the Cholesky triangular form of the
mass matrices where the entries are given as simple functions of the mass
eigenstates and the diagonalizing transformation entries. Finally, motivated by
the possibility of vanishing zero Yukawa mass entries in several D-brane and
F-theory constructions due to the geometry of the internal space, we analyse in
detail all possible texture-zeroes mass matrices within the proposed new
context. These new texture-zeroes are compared to those existing in the
literature while D-brane inspired cases are worked out in detail.Comment: 58 pages, 7 figure
Frequent use of paracetamol and risk of allergic disease among women in an Ethiopian population
Introduction
The hypothesis that paracetamol might increase the risk of asthma and other allergic diseases have gained support from a range of independent studies. However, in studies based in developed countries, the possibility that paracetamol and asthma are associated through aspirin avoidance is difficult to exclude.
Objectives
To explore this hypothesis among women in a developing country, where we have previously reported aspirin avoidance to be rare.
Methods
In 2005/6 a population based cohort of 1065 pregnant women was established in Butajira, Ethiopia and baseline demographic data collected. At 3 years post birth, an interview-based questionnaire administered to 945 (94%) of these women collected data on asthma, eczema, and hay fever in the past 12 month, frequency of paracetamol use and potential confounders. Allergen skin tests to Dermatophagoides pteronyssinus and cockroach were also performed. The independent effects of paracetamol use on allergic outcomes were determined using multiple logistic regression analysis.
Findings
The prevalence of asthma, eczema and hay fever was 1.7%, 0.9% and 3.8% respectively; of any one of these conditions 5.5%, and of allergen sensitization 7.8%. Paracetamol use in the past month was reported by 29%, and associations of borderline significance were seen for eczema (adjusted OR (95% CI) = 8.51 (1.68 to 43.19) for 1–3 tablets and 2.19 (0.36 to 13.38) for ≥4 tablets, compared to no tablets in the past month; overall p = 0.055) and for ‘any allergic condition’ (adjusted OR (95% CI) = 2.73 (1.22 to 6.11) for 1–3 tablets and 1.35 (0.67 to 2.70) for ≥4 tablets compared to 0 in the past month; overall p = 0.071).
Conclusions
This study provides further cross-sectional evidence that paracetamol use increases the risk of allergic disease
Symmetries of Abelian Orbifolds
Using the Polya Enumeration Theorem, we count with particular attention to
C^3/Gamma up to C^6/Gamma, abelian orbifolds in various dimensions which are
invariant under cycles of the permutation group S_D. This produces a collection
of multiplicative sequences, one for each cycle in the Cycle Index of the
permutation group. A multiplicative sequence is controlled by its values on
prime numbers and their pure powers. Therefore, we pay particular attention to
orbifolds of the form C^D/Gamma where the order of Gamma is p^alpha. We propose
a generalization of these sequences for any D and any p.Comment: 75 pages, 13 figures, 30 table
The Conformal Sector of F-theory GUTs
D3-brane probes of exceptional Yukawa points in F-theory GUTs are natural
hidden sectors for particle phenomenology. We find that coupling the probe to
the MSSM yields a new class of N = 1 conformal fixed points with computable
infrared R-charges. Quite surprisingly, we find that the MSSM only weakly mixes
with the strongly coupled sector in the sense that the MSSM fields pick up
small exactly computable anomalous dimensions. Additionally, we find that
although the states of the probe sector transform as complete GUT multiplets,
their coupling to Standard Model fields leads to a calculable threshold
correction to the running of the visible sector gauge couplings which improves
precision unification. We also briefly consider scenarios in which SUSY is
broken in the hidden sector. This leads to a gauge mediated spectrum for the
gauginos and first two superpartner generations, with additional contributions
to the third generation superpartners and Higgs sector.Comment: v2: 51 pages, 2 figures, remark added, typos correcte
Are your covariates under control? How normalization can re-introduce covariate effects
Many statistical tests rely on the assumption that the residuals of a model are normally distributed. Rank-based inverse normal transformation (INT) of the dependent variable is one of the most popular approaches to satisfy the normality assumption. Studies regularly adjust for covariates and then normalize the residuals. This study investigated the effect of regressing covariates against the dependent variable and then applying rank-based INT to the residuals. The correlation between the dependent variable and covariates at each stage of processing was assessed. An alternative approach was tested of applying rank-based INT to the dependent variable before regressing covariates was tested. Analyses based on both simulated and real data examples demonstrated that applying rank-based INT to the dependent variable residuals after regressing out covariates re-introduces a linear correlation between the dependent variable and covariates in almost all situations. This will increase type-1 errors and reduce power. Our proposed alternative approach, where rank-based INT was applied prior to controlling for covariate effects, gave residuals that were normally distributed and linearly uncorrelated with covariates. This approach is therefore recommended
Flavour in supersymmetry: horizontal symmetries or wave function renormalisation
We compare theoretical and experimental predictions of two main classes of
models addressing fermion mass hierarchies and flavour changing neutral
currents (FCNC) effects in supersymmetry: Froggatt-Nielsen (FN) U(1) gauged
flavour models and Nelson-Strassler/extra dimensional models with hierarchical
wave functions for the families. We show that whereas the two lead to identical
predictions in the fermion mass matrices, the second class generates a stronger
suppression of FCNC effects. We prove that, whereas at first sight the FN setup
is more constrained due to anomaly cancelation conditions, imposing unification
of gauge couplings in the second setup generates conditions which precisely
match the mixed anomaly constraints in the FN setup. Finally, we provide an
economical extra dimensional realisation of the hierarchical wave functions
scenario in which the leptonic FCNC can be efficiently suppressed due to the
strong coupling (CFT) origin of the electron mass.Comment: 23 page
Acute fibrinous and organising pneumonia: a case report and review of the literature
<p>Abstract</p> <p>Introduction</p> <p>Organising pneumonia is a distinct histopathological entity characterized by intra-alveolar buds of granulation tissue, called Masson bodies, which mainly comprise of activated fibroblasts and loose connective tissue. This histopathologic pattern has been described in idiopathic cases, characterizing cryptogenic organising pneumonia as well as in the context of pulmonary infection, drug-induced pneumonitis and following lung transplantation. Although distinct as a clinical and pathological entity, community organising pneumonia may present with atypical clinical and pathological features, such as intra-alveolar fillings of fibrin balls and organising tissue that resembles acute respiratory distress syndrome or diffuse alveolar damage. The latter characteristics constitute a recently described anatomoclinical entity called acute fibrinous and organising pneumonia.</p> <p>Case presentation</p> <p>Here, we describe a rare case of acute fibrinous and organising pneumonia, in an otherwise healthy 65-year-old Greek woman who complained of dry cough, fever, weight loss and progressive dyspnoea. She had never been a smoker. Her clinical symptoms showed a rapid deterioration in the two weeks before admission, despite a course of oral antibiotics. After excluding infection and malignancy with routine laboratory tests and flexible bronchoscopy, high resolution computed tomography and video assisted thoracoscopic lung biopsy were performed. Diagnosis was based on radiological features typical of community organising pneumonia coupled with pathologic features characteristic of acute fibrinous and organising pneumonia. The patient was treated with corticosteroids and showed excellent clinical and radiological response three months after treatment initiation.</p> <p>Conclusion</p> <p>Acute fibrinous and organising pneumonia is an extremely rare pathologic entity, often misdiagnosed as typical community organising pneumonia. To our knowledge, this is the seventh case of acute fibrinous and organising pneumonia in the literature, with no identifiable cause or association in a female patient, with no underlying lung disease or known exposures and with an unremarkable previous medical history. We highlight the need for careful review of lung biopsies from patients with clinical and radiologic characteristics typical of community organising pneumonia. Although it remains uncertain whether fibrin alters the favourable prognosis and treatment response of community organising pneumonia, it becomes obvious that a thorough pathologic review, apart from establishing the diagnosis of acute fibrinous and organising pneumonia, may predict a more unfavorable outcome therefore alerting the clinician to administer more aggressive and prolonged therapeutic regimens.</p
Do contaminants originating from state-of-the-art treated wastewater impact the ecological quality of surface waters?
Since the 1980s, advances in wastewater treatment technology have led to considerably improved surface water quality in the urban areas of many high income countries. However, trace concentrations of organic wastewater-associated contaminants may still pose a key environmental hazard impairing the ecological quality of surface waters. To identify key impact factors, we analyzed the effects of a wide range of anthropogenic and environmental variables on the aquatic macroinvertebrate community. We assessed ecological water quality at 26 sampling sites in four urban German lowland river systems with a 0–100% load of state-of-the-art biological activated sludge treated wastewater. The chemical analysis suite comprised 12 organic contaminants (five phosphor organic flame retardants, two musk fragrances, bisphenol A, nonylphenol, octylphenol, diethyltoluamide, terbutryn), 16 polycyclic aromatic hydrocarbons, and 12 heavy metals. Non-metric multidimensional scaling identified organic contaminants that are mainly wastewater-associated (i.e., phosphor organic flame retardants, musk fragrances, and diethyltoluamide) as a major impact variable on macroinvertebrate species composition. The structural degradation of streams was also identified as a significant factor. Multiple linear regression models revealed a significant impact of organic contaminants on invertebrate populations, in particular on Ephemeroptera, Plecoptera, and Trichoptera species. Spearman rank correlation analyses confirmed wastewater-associated organic contaminants as the most significant variable negatively impacting the biodiversity of sensitive macroinvertebrate species. In addition to increased aquatic pollution with organic contaminants, a greater wastewater fraction was accompanied by a slight decrease in oxygen concentration and an increase in salinity. This study highlights the importance of reducing the wastewater-associated impact on surface waters. For aquatic ecosystems in urban areas this would lead to: (i) improvement of the ecological integrity, (ii) reduction of biodiversity loss, and (iii) faster achievement of objectives of legislative requirements, e.g., the European Water Framework Directive
Lung cancer in HIV patients and their parents: A Danish cohort study
<p>Abstract</p> <p>Background</p> <p>HIV patients are known to be at increased risk of lung cancer but the risk factors behind this are unclear.</p> <p>Methods</p> <p>We estimated the cumulative incidence and relative risk of lung cancer in 1) a population of all Danish HIV patients identified from the Danish HIV Cohort Study (n = 5,053) and a cohort of population controls matched on age and gender (n = 50,530) (study period; 1995 - 2009) and 2) their parents (study period; 1969 - 2009). Mortality and relative risk of death after a diagnosis of lung cancer was estimated in both populations.</p> <p>Results</p> <p>29 (0.6%) HIV patients vs. 183 (0.4%) population controls were diagnosed with lung cancer in the observation period. HIV patients had an increased risk of lung cancer (adjusted incidence rate ratio (IRR); 2.38 (95% CI; 1.61 - 3.53)). The IRR was considerably increased in HIV patients who were smokers or former smokers (adjusted IRR; 4.06 (95% CI; 2.66 - 6.21)), male HIV patients with heterosexual route of infection (adjusted IRR; 4.19 (2.20 - 7.96)) and HIV patients with immunosuppression (adjusted IRR; 3.25 (2.01 - 5.24)). Both fathers and mothers of HIV patients had an increased risk of lung cancer (adjusted IRR for fathers; 1.31 (95% CI: 1.09 - 1.58), adjusted IRR for mothers 1.35 (95% CI: 1.07 - 1.70)). Mortality after lung cancer diagnose was increased in HIV patients (adjusted mortality rate ratio 2.33 (95%CI; 1.51 - 3.61), but not in the parents. All HIV patients diagnosed with lung cancer were smokers or former smokers.</p> <p>Conclusion</p> <p>The risk was especially increased in HIV patients who were smokers or former smokers, heterosexually infected men or immunosuppressed. HIV appears to be a marker of behavioural or family related risk factors that affect the incidence of lung cancer in HIV patients.</p
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