Monopoles, strings and dark matter

We develop a scenario whereby monopoles in a hidden sector yield a decaying dark matter candidate of interest for the PAMELA and FERMI $e^\pm$ excesses. The monopoles are not completely hidden due to a very small kinetic mixing and a hidden photon mass. The latter also causes the monopoles and anti-monopoles to be connected by strings. The resulting long-lived objects eventually decay to hidden photons which tend to escape galactic cores before decaying. The mass scales are those of the hidden photon ($\approx 500$ MeV), the monopole ($\approx 3$ TeV) and the mixing scale (close to the Planck scale). A gauge coupling in the hidden sector is the only other parameter. This coupling must be strong and this results in light point-like monopoles and light thin strings.Comment: 21 pages, various improvements and additional reference

Spin and charge optical conductivities in spin-orbit coupled systems

We study the frequency dependent spin- and charge- conductivity tensors of a two-dimensional electron gas (2DEG) with Rashba and Dresselhaus spin-orbit interaction. We show that the angular anisotropy of the spin-splitting energy induced by the interplay between the Rashba and Dresselhaus couplings gives rise to a characteristic spectral behavior of the spin and charge response which is significantly different from that of pure Rashba or Dresselhaus case. Such new spectral structures open the possibility for control of the optical response by applying an external bias and/or by adjusting the light frequency. In addition, it is shown that the relative strength of the spin-orbit coupling parameters can be obtained through optical probing.Comment: 13 pages, 4 figures. Revised versio

Spin torque contribution to the a.c. spin Hall conductivity

Using the recently proposed definition of a conserved spin-current operator [J. Shi et al., Phys. Rev. Lett. 96, 076604 (2006)] we explore the frequency dependent spin Hall conductivity for a two-dimensional electron gas with Rashba and Dresselhaus spin-orbit interaction in response to an oscillating electric field. We show that the optical spectrum of the spin Hall conductivity exhibit remarkable changes when the new definition of spin current is applied. Such behavior is mainly due to a significant contribution of the spin torque term which is absent in the conventional form of the spin current. In addition, it is observed that the magnitude and direction of the dynamic spin Hall current strongly depends on the electric field frequency as with the interplay of the spin-orbit coupling strengths.Comment: 8 pages, 4 figures, pape

Changes in the diet and body size of a small herbivorous mammal (hispid cotton rat, \u3ci\u3eSigmodon hispidus\u3c/i\u3e) following the late Pleistocene megafauna extinction

The catastrophic loss of large-bodied mammals during the terminal Pleistocene likely led to cascading effects within communities. While the extinction of the top consumers probably expanded the resources available to survivors of all body sizes, little work has focused on the responses of the smallest mammals. Here, we use a detailed fossil record from the southwestern United States to examine the response of the hispid cotton rat Sigmodon hispidus to biodiversity loss and climatic change over the late Quaternary. In particular, we focus on changes in diet and body size. We characterize diet through carbon (δ13C) and nitrogen (δ15N) isotope analysis of bone collagen in fossil jaws and body size through measurement of fossil teeth; the abundance of material allows us to examine population level responses at millennial scale for the past 16 ka. Sigmodon was not present at the cave during the full glacial, first appearing at ~16 ka after ice sheets were in retreat. It remained relatively rare until ~12 ka when warming tempera­tures allowed it to expand its species range northward. We find variation in both diet and body size of Sigmodon hispidus over time: the average body size of the population varied by ~20% (90–110 g) and mean δ13C and δ15N values ranged between −13.5 to −16.5‰ and 5.5 to 7.4‰ respectively. A state–space model suggested changes in mass were influenced by diet, maximum temperature and community structure, while the modest changes in diet were most influenced by community structure. Sigmodon maintained a fairly similar dietary niche over time despite contemporaneous changes in climate and herbivore community composition that followed the megafauna extinc­tion. Broadly, our results suggest that small mammals may be as sensitive to shifts in local biotic interactions within their ecosystem as they are to changes in climate and large-scale biodiversity loss

Incorporating unobserved heterogeneity and multiple event types in survival models : a Bayesian approach

This thesis covers theoretical and practical aspects of Bayesian inference and survival analysis, which is a powerful tool for the analysis of the time until a certain event of interest occurs. This dissertation focuses on non-standard models inspired by features of real datasets that are not accommodated by conventional models. Materials are divided in two parts. The first and more extended part relates to the development of flexible parametric lifetime distributions motivated by the presence of anomalous observations and other forms of unobserved heterogeneity. Chapter 2 presents the use of mixture families of lifetime distributions for this purpose. This idea can be interpreted as the introduction of an observation-specific random effect on the survival distribution. Two families generated via this mechanism are studied in Chapter 3. Covariates are introduced through an accelerated failure times representation, for which the interpretation of the regression coefficients is invariant to the distribution of the random effect. The Bayesian model is completed using reasonable (improper) priors that require a minimum input from practitioners. Under mild conditions, these priors induce a well-defined posterior distribution. In addition, the mixture structure is exploited in order to propose a novel method for outlier detection where anomalous observations are identified via the posterior distribution of the individual-specific random effects. The analysis is illustrated in Chapter 4 using three real medical applications. Chapter 5 comprises the second part of this thesis, which is motivated in the context of university outcomes. The aim of the study is to identify determinants of the length of stay at university and its associated academic outcome for undergraduate students of the Pontificia Universidad Católica de Chile. In this setting, survival times are defined as the time until the end of the enrollment period, which can relate to different reasons - graduation or dropout - that are driven by different processes. Hence, a competing risks model is employed for the analysis. Model uncertainty is handled through Bayesian model averaging, which leads to a better predictive performance than choosing a unique model. The output of this analysis does not account for all features of this complex dataset yet it provides a better understanding of the problem and a starting point for future research. Finally, Chapter 6 summarizes the main findings of this work and suggests future extensions

Sexual well-being and diurnal cortisol after prostate cancer treatment.

Sexual dysfunction and psychological distress are common after prostate cancer. Research has not examined the role of neuroendocrine markers of stress (e.g. cortisol). This study examines whether sexual functioning or sexual bother is associated with diurnal cortisol. Men treated for prostate cancer completed the University of California-Los Angeles Prostate Cancer Index and provided saliva samples four times daily for cortisol assessment. Higher sexual bother, but not sexual functioning, was associated with steeper cortisol slope. Better sexual functioning, and not sexual bother, was significantly associated with the cortisol awakening response. Assessment of stress and stress-reducing interventions might be warranted in sexual rehabilitation after prostate cancer

The rise and fall of shark functional diversity over the last 66 million years

AimModern sharks are a diverse and highly threatened group playing important roles in ecosystems. They have an abundant fossil record spanning at least 250 million years (Myr), consisting primarily of isolated teeth. Throughout their evolutionary history, sharks have faced multiple environmental changes and extinction events. Here, we aim to use dental characters to quantify how shark functional diversity has changed during the last 66 Myr.LocationGlobal.Time periodCenozoic era (66–0 million years ago; Ma).Major taxa studiedSharks (Selachii).MethodsWe complied a dataset of over 9000 shark teeth belonging to 537 taxa from museum collections and scientific literature and measured six dental characters strongly linked with functional traits. We then quantified different functional diversity metrics across Cenozoic time bins, compared them against null expectations and identified the most important taxa contributing to maintaining functional diversity.ResultsSharks displayed relatively high functional diversity during the Cenozoic, with 66%–87% of the functional space being occupied for ~60 Myr (Palaeocene to Miocene). High levels of functional redundancy during this time resulted in larger‐than‐expected functional richness; but a large decline (−45%) in redundancy in the Oligocene (~30 Ma) left shark functional diversity highly vulnerable to further loss. Shark functional diversity declined from the late Miocene (~10 Ma) onwards, losing 44% of functional richness by the Recent. Extinct sharks disproportionally contributed to the Cenozoic functional diversity and spanned a wider range of functional space than extant sharks, with the loss of mid‐sized suction feeders and large‐bodied predators driving functional declines.Main conclusionsAfter maintaining high levels of functional diversity for most of the Cenozoic, sharks lost nearly half of their functional diversity in the last ~10 Myr. Current anthropogenic pressures are therefore likely eroding an already diminished shark functional diversity, leaving future communities ecologically deprived compared with their thriving geological past

Category 5

Follow Elizabeth and her family through this family oriented video series which highlights topics such as preparing for a hurricane, how to help those affected by a storm and raises awareness for mental health after a natural disaster. Nexus Maximus IV The Challenge: Innovation for Refugees and Displaced Populations One of the great challenges of our time is how to help refugees and displaced populations, and how to prevent the causes in the first place. Every minute, 24 people around the world are forced to flee their homes. That’s 34,000 people a day who leave everything behind in the hope of finding safety and a better tomorrow. The impact of war, political, racial and religious conflict, and environmental crises of famine and climate change, have caused great suffering and there is a great opportunity to do better. The issues these populations and the countries who receive them face are diverse and complex. They include public health, housing/built environment, cultural integration, public safety, employment/economic and more. How can innovation address these challenges? How do we create the social systems and products to support a healthy, safe and integrated program for refugees? How do we address the physical, emotional, and social needs of refugees to restore hope and opportunity? The solutions may be as far ranging as the challenges, exploring the acute needs during a crisis, as well as the chronic needs of the permanently displaced; looking at immigration and adjustments to new cultures. We encourage participants to draw upon all disciplines, from health professions to architecture, engineering to design, ethics, communication and every way of thinking we have, to find better ways to innovate on physical solutions, processes, policies, systems, and more. Recap of poster presentationshttps://jdc.jefferson.edu/nexusmaximus/1015/thumbnail.jp