Natural Four-Generation Mass Textures in MSSM Brane Worlds

A fourth generation of Standard Model (SM) fermions is usually considered unlikely due to constraints from direct searches, electroweak precision measurements, and perturbative unitarity. We show that fermion mass textures consistent with all constraints may be obtained naturally in a model with four generations constructed from intersecting D6 branes on a T^6/(Z_2 x Z_2) orientifold. The Yukawa matrices of the model are rank 2, so that only the third- and fourth-generation fermions obtain masses at the trilinear level. The first two generations obtain masses via higher-order couplings and are therefore naturally lighter. In addition, we find that the third and fourth generation automatically split in mass, but do not mix at leading order. Furthermore, the SM gauge couplings automatically unify at the string scale, and all the hidden-sector gauge groups become confining in the range 10^{13}--10^{16} GeV, so that the model becomes effectively a four-generation MSSM at low energies.Comment: Accepted for publication in Physical Review

Beyond Capitation: How New Payment Experiments Seek to Find the \u27Sweet Spot\u27 in Amount of Risk Providers and Payers Bear

A key issue in the decades-long struggle over US health care spending is how to distribute liability for expenses across all market participants, from insurers to providers. The rise and abandonment in the 1990s of capitation payments—lump-sum, per person payments to health care providers to provide all care for a specified individual or group—offers a stark example of how difficult it is for providers to assume meaningful financial responsibility for patient care. This article chronicles the expansion and decline of the capitation model in the 1990s. We offer lessons learned and assess the extent to which these lessons have been applied in the development of contemporary forms of provider cost sharing, particularly accountable care organizations, which in effect constitute a search for the “sweet spot,” or appropriate place on a spectrum, between providers and payers with respect to the degree of risk they absorb

Exact 1-D Model for Coherent Synchrotron Radiation with Shielding and Bunch Compression

Coherent Synchrotron Radiation has been studied effectively using a 1-dimensional model for the charge distribution in the realm of small angle approximations and high energies. Here we use Jefimenko's form of Maxwell's equations, without such approximations, to calculate the exact wake-fields due to this effect in multiple bends and drifts. It has been shown before that the influence of a drift can propagate well into a subsequent bend. We show, for reasonable parameters, that the influence of a previous bend can also propagate well into a subsequent bend, and that this is especially important at the beginning of a bend. Shielding by conducting parallel plates is simulated using the image charge method. We extend the formalism to situations with compressing and decompressing distributions, and conclude that simpler approximations to bunch compression usually overestimates the effect. Additionally, an exact formula for the coherent power radiated by a Gaussian bunch is derived by considering the coherent synchrotron radiation spectrum, and is used to check the accuracy of wake-field calculations

The application of passive sampler (DGT) technology for improved understanding of metal behaviour at a marine disposal site

Metal behaviour and availability at a contaminated dredge material disposal site within UK waters has been investigated using Diffusive Gradient in Thin films (DGT) passive sampling technology. Three stations representing contrasting history and presence of maintenance dredge disposal, including a control station outside the disposal site, have been studied and depth profiles of fluxes of different metals (Fe, Mn, Pb, Cu, Cd, Cr, Ni, Zn) to the binding gel (Chelex 100) have been derived. Higher flux rates and shallower mobilisation of metals (Mn and Fe) to the binding gel were observed at the disposal stations compared to the control station. Here we describe metal mobilization at different depths, linking the remobilization of Fe2+ and Mn2+ to the sediment (re)supply of other heavy metals of interest with a focus on Cd, Ni and Pb and as they are on the Water Framework Directive (WFD) list of priority substances and OSPAR list of priority pollutants. Results showed that Cd, Pb and Ni exhibited signs of resupply at the sediment-water interface (SWI). There was a potential increased mobilisation and source to the water column of Pb and Ni at the disposal site stations, but there was no Cd source, despite higher total loadings. This information has the potential to improve our current understanding of metal cycles at disposal sites. This work can be used as an indication of likely metal bioavailability and also assist in determining whether the sites act as sources or sinks of heavy metals. This information could assist disposal site monitoring and dredge material licensing

Supergravity and Superstring Signatures of the One-Parameter Model at LHC

Many string constructions have a classical no-scale structure, resulting in a one-parameter model (OPM) for the supersymmetry breaking soft terms. As a highly constrained subset of mSUGRA, the OPM has the potential to be predictive. Conversely, if the observed superpartner spectrum at LHC is a subset of the OPM parameter space, then this may provide a clue to the underlying theory at high energies. We investigate the allowed supersymmetry parameter space for a generic one-parameter model taking into account the most recent experimental constraints. We find that in the strict moduli scenario, there are no regions of the parameter space which may satisfy all constraints. However, for the dilaton scenario, there are small regions of the parameter space where all constraints may be satisfied and for which the observed dark matter density may be generated. We also survey the possible signatures which may be observable at the Large Hadron Collider (LHC). Finally, we compare collider signatures of OPM to those from a model with non-universal soft terms, in particular those of an intersecting D6-brane model. We find that it may be possible to distinguish between these diverse scenarios at LHC.Comment: 25 pages, 10 figures, accepted for publication in PR

Don’t dismiss conflict-of-interest concerns in IVF, they have a basis

It’s estimated over 5 million children have been born worldwide as a result of assisted reproductive technology treatments. Assisted reproductive technology, an umbrella term that includes in vitro fertilisation (IVF), is a highly profitable global industry, and fertility clinics are increasingly regarded as an attractive investment option. In 2014, two major IVF clinics - Virtus and Monash IVF — floated on the stock exchange. Excited financial analysts observed at the time that: people will pay almost anything to have a baby. Over the past 12 months, there have been numerous critical media analyses of the IVF industry in Australia, including Monday night’s ABC Four Corners program, The Baby Business. The episode suggested IVF doctors are recommending treatments that are expensive, unsafe and likely to be futile. The following morning the Fertility Society of Australia rejected these assertions, saying: Four Corners presented no evidence to support these claims. One of the claims made in the program was that IVF doctors have a financial incentive to treat women with the more invasive practice of IVF. The program suggested this financial incentive conflicts with the doctor’s duty of care towards the patient. Four Corners highlighted the conflicted nature of commercialised IVF, where some IVF doctors are more concerned about their own interests (making money for themselves or their clinics) than they are about their patients. Not surprisingly, the Fertility Society of Australia strongly denied such conflicts of interest exist. It argued that the profession is both highly ethical and highly regulated

Are infestations of Cymomelanodactylus killing Acropora cytherea in the Chagos archipelago?

Associations between branching corals and infaunal crabs are well known, mostly due to the beneficial effects of Trapezia and Tetralia crabs in protecting host corals from crown-of-thorns starfish (e.g., Pratchett et al. 2000) and/or sedimentation (Stewart et al. 2006). These crabs are obligate associates of live corals and highly prevalent across suitable coral hosts, with 1–2 individuals per colony (Patton 1994). Cymo melanodactylus (Fig. 1) are also prevalent in branching corals, mostly Acropora, and are known to feed on live coral tissue, but are generally found in low abundance (<3 per colony) and do not significantly affect their host corals (e.g., Patton 1994). In the Chagos archipelago, however, infestations of Cymo melanodactylus were found on recently dead and dying colonies of Acropora cytherea

Changes in Maternal Gene Expression in Olfactory Circuits in the Immediate Postpartum Period

Regulation of maternal behavior in the immediate postpartum period involves neural circuits in reward and homeostasis systems responding to cues from the newborn. Our aim was to assess one specific regulatory mechanism: the role that olfaction plays in the onset and modulation of parenting behavior. We focused on changes in gene expression in olfactory brain regions, examining nine genes found in previous knockout studies to be necessary for maternal behavior. Using a quantitative PCR (qPCR)-based approach, we assessed changes in gene expression in response to exposure to pups in 11 microdissected olfactory brain regions. Over the first postpartum days, all nine genes were detected in all 11 regions (at differing levels) and their expression changed in response to pup exposure. As a general trend, five genes (Dbh, Esr1, FosB, Foxb1, and Oxtr) were found to decrease their expression in most of the olfactory regions examined, while two genes (Mest and Prlr) were found to increase expression. Nos1 and Peg3 levels remained relatively stable except in the accessory olfactory bulb (AOB), where greater than fourfold increases in expression were observed. The largest magnitude expression changes in this study were found in the AOB, which mediates a variety of olfactory cues that elicit stereotypic behaviors such as mating and aggression as well as some non-pheromone odors. Previous analyses of null mice for the nine genes assessed here have rarely examined olfactory function. Our data suggest that there may be olfactory effects in these null mice which contribute to the observed maternal behavioral phenotypes. Collectively, these data support the hypothesis that olfactory processing is an important sensory regulator of maternal behavior

Two New Tetraphyllidean Cestodes from \u3ci\u3ePotamotrygon circularis\u3c/i\u3e Garman (Chondrichthyes: Potamotrygonidae) in the Itacnai River, Brazill

The new genus Rhinebothroides is proposed to include three species of Rhinebothriumlike cestodes parasitizing freshwater stingrays in South America. They differ from Rhinebothrium species by having squared rather than elongate bothridia, by possessing internal seminal vesicles, and by exhibiting terminal genitalia at the ovarian level. Rhinebothroides circularisi sp. n. in Potamotrygon circularis from the Itacuai River in northwestern Brazil differs from R. moralarai by having more testes and bothridial loculi and differs from R. scorzai by lacking vitelline follicles proximate to the genital pore, by having a straight rather than coiled vagina, and by possessing craspedote rather than acraspedote proglottids. Potamotrygon circularis from the Itacuai River also hosted Potamotrygonocestus amazonensis sp. n. which differs from the only other member of the genus, P. magdalenensis, by having bothridial hooks 58-78µm long rather than 43-55 µm long, by possessing a shallow genital atrium rather than lacking one, and by having follicular rather than compact vitellaria