3,668 research outputs found
Bs Mixing and Electric Dipole Moments in MFV
We analyze the general structure of four-fermion operators capable of
introducing CP-violation preferentially in Bs mixing within the framework of
Minimal Flavor Violation. The effect requires a minimum of O(Yu^4 Yd^4) Yukawa
insertions, and at this order we find a total of six operators with different
Lorentz, color, and flavor contractions that lead to enhanced Bs mixing. We
then estimate the impact of these operators and of their close relatives on the
possible sizes of electric dipole moments (EDMs) of neutrons and heavy atoms.
We identify two broad classes of such operators: those that give EDMs in the
limit of vanishing CKM angles, and those that require quark mixing for the
existence of non-zero EDMs. The natural value for EDMs from the operators in
the first category is up to an order of magnitude above the experimental upper
bounds, while the second group predicts EDMs well below the current sensitivity
level. Finally, we discuss plausible UV-completions for each type of operator.Comment: 11 pages; v2: references adde
Transformation and fate of microphytobenthos carbon in subtropical, intertidal sediments: potential for long-term carbon retention revealed by <sup>13</sup>C-labeling
Microphytobenthos (MPB) are ubiquitous in coastal sediments, but the fate of
their production (carbon biomass) is poorly defined. The processing and fate
of MPB-derived carbon in subtropical intertidal sediments was investigated
through in situ labeling with <sup>13</sup>C-bicarbonate. Of the added <sup>13</sup>C,
100% was fixed within ~ 4 h, suggesting that MPB
productivity was limited by inorganic carbon availability. Although there
was rapid transfer of <sup>13</sup>C to bacteria (within 12 h), a relatively small
fraction of <sup>13</sup>C was transferred to heterotrophs (up to 12.5% of
total fixed <sup>13</sup>C into bacteria and 0.01% into foraminifera). MPB was
the major reservoir for <sup>13</sup>C throughout the study, suggesting that
production of extracellular polymeric substances was limited and/or MPB
recycled <sup>13</sup>C. This retention of <sup>13</sup>C was reflected in remarkably
slow estimated turnover times for the MPB community (66â100 d). Over 31 d,
~ 70% of the <sup>13</sup>C was lost from sediments. This was
primarily via resuspension (~ 55%), enhanced by elevated
freshwater flow following rainfall. A further ~ 13% was
lost via fluxes of dissolved inorganic carbon during inundation. However,
<sup>13</sup>C losses via dissolved organic carbon fluxes from inundated sediments
(0.5%) and carbon dioxide fluxes from exposed sediments (<0.1%) were minimal. The retention of ~ 30% of the carbon
fixed by MPB within one tidal exposure after > 30 d, despite high
resuspension, demonstrates the potentially substantial longer term retention
of MPB-derived carbon in unvegetated sediments and suggests that MPB may
contribute to carbon burial ("blue carbon")
Music in advertising and consumer identity: The search for Heideggerian authenticity
This study discusses netnographic findings involving 472 YouTube postings categorized to identify themes regarding consumersâ experience of music in advertisements. Key themes relate to musical taste, musical indexicality, musical repetition and musical authenticity. Postings reveal how music conveys individual taste and is linked to personal memories and Heideggerâs coincidental time where moments of authenticity may be triggered in a melee of emotions, memories and projections. Identity protection is enabled as consumers frequently resist advertisersâ attempts to use musical repetition to impose normative identity. Critiques of repetition in the music produce Heideggerian anxiety leading to critically reflective resistance. Similarly, where advertising devalues the authenticity of iconic pieces of music, consumers often resist such authenticity transgressions as a threat to their own identity. The Heideggerian search for meaning in life emphasizes the significance of philosophically driven ideological authenticity in consumersâ responses to music in advertisements
Secondary school pupils' preferences for different types of structured grouping practices
The aim of this paper is to explore pupilsâ preferences for particular types of grouping practices an area neglected in earlier research focusing on the personal and social outcomes of ability grouping. The sample comprised over 5,000 year 9 pupils (aged 13-14 years) in 45 mixed secondary comprehensive schools in England. The schools represented three levels of ability grouping in the lower school (years 7 to 9). Pupils responded to a questionnaire which explored the types of grouping that they preferred and the reasons for their choices. The majority of pupils preferred setting, although this was mediated by their set placement, type of school, socio-economic status and gender. The key reason given for this preference was that it enabled work to be matched to learning needs. The paper considers whether there are other ways of achieving this avoiding the negative social and personal outcomes of setting for some pupils
Understanding the Effects of the Neighbourhood Built Environment on Public Health with Open Data
The investigation of the effect of the built environment in a neighbourhood and how it impacts residents' health is of value to researchers from public health policy to social science. The traditional methods to assess this impact is through surveys which lead to temporally and spatially coarse grained data and are often not cost effective. Here we propose an approach to link the effects of neighbourhood services over citizen health using a technique that attempts to highlight the cause-effect aspects of these relationships. The method is based on the theory of {\em propensity score matching with multiple `doses'} and it leverages existing fine grained open web data. To demonstrate the method, we study the effect of sport venue presence on the prevalence of antidepressant prescriptions in over 600 neighbourhoods in London over a period of three years. We find the distribution of effects is approximately normal, centred on a small negative effect on prescriptions with increases in the availability of sporting facilities, on average. We assess the procedure through some standard quantitative metrics as well as matching on synthetic data generated by modelling the real data. This approach opens the door to fast and inexpensive alternatives to quantify and continuously monitor effects of the neighborhood built environment on population health.Cambridge Trust and King's Colleg
Normocalcemic hyperparathyroidism : study of its prevalence and natural history
Context
Normocalcemic hyperparathyroidism (NPHPT) is characterized by persistently normal calcium levels and elevated parathyroid hormone (PTH) values, after excluding other causes of secondary hyperparathyroidism. The prevalence of the disease varies greatly and the data on the natural history of this disease are sparse and inconclusive.
Objectives
The objectives of this study are to describe the prevalence of NPHPT and its natural history in a referral population and to compare the variability of serum calcium with a group of patients with primary hyperparathyroidism (PHPT).
Design
A retrospective study was conducted over 5 years.
Setting
The setting for this study was a metabolic bone referral center.
Patients
A total of 6280 patients were referred for a bone mineral density measurement (BMD).
Main Outcome Measures
The prevalence and natural history of NPHPT and variability of calcium were the main outcome measures.
Results
We identified NPHPT patients using data from the day of the BMD measurement. We excluded patients with low estimated glomerular filtration rate (eGFR) or vitamin D, or with no measurements available. Based on the evaluation of their medical files, we identified 11 patients with NPHPT (prevalence 0.18%). Only 4 patients had consistent normocalcemia throughout their follow-up, with only 2 also having consistently high PTH. None had consistently normal eGFR or vitamin D.
Intermittent hypercalcemia was present in 7 of the 11 NPHPT patients. The mean adjusted calcium was found to be significantly lower in the NPHPT group compared with the PHPT group but higher than the control group. PTH was similar for NPHPT and PHPT. These 2 groups had similar variability in serum calcium.
Conclusions
NPHPT patients often have episodes of hypercalcemia. We believe that NPHPT is a mild form of PHPT
Emergence of cooperative dynamics in fully packed classical dimers
We study the behavior of classical dimer coverings of the square latticeâa paradigmatic model for systems subject to constraintsâevolving under local stochastic dynamics, by means of Monte Carlo simulations and theoretical arguments. We observe clear signatures of correlated dynamics in both global and local observables and over a broad range of time scales, indicating a breakdown of the simple continuum description that approximates well the statics. We show that this collective dynamics can be understood in terms of one-dimensional âstringsâ of high mobility, which govern both local and long-wavelength dynamical properties. We introduce a coarse-grained description of the strings, based on the EdwardsâWilkinson model, which leads to exact results in the limit of low string density and provides a detailed qualitative understanding of the dynamics in all flux sectors. We discuss the implications of our results for the dynamics of constrained systems more generally
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