Spousal separation, selectivity and contextual effects: exploring the relationship between international labour migration and fertility in post-Soviet Tajikistan

This paper contributes to the sparse literature on the impact of temporary migration on fertility in origin areas. It examines the case of male labour migration from post-Soviet Tajikistan, a significant and relatively recent phenomenon. Fertility and migration models are solved simultaneously to account for cross-process correlation. There is clear evidence for a short-term disruptive effect of spousal separation, but it is too early to assess the implications for completed fertility. While there is no evidence for unobserved selectivity at the couple level, there is a significant positive correlation between the migration and fertility processes at the community level.fertility, migration, multiprocess model, selectivity, spousal separation, Tajikistan

Effectively Stable Dark Matter

We study dark matter (DM) which is cosmologically long-lived because of standard model (SM) symmetries. In these models an approximate stabilizing symmetry emerges accidentally, in analogy with baryon and lepton number in the renormalizable SM. Adopting an effective theory approach, we classify DM models according to representations of $SU(3)_C\times SU(2)_L\times U(1)_Y \times U(1)_B\times U(1)_L$, allowing for all operators permitted by symmetry, with weak scale DM and a cutoff at or below the Planck scale. We identify representations containing a neutral long-lived state, thus excluding dimension four and five operators that mediate dangerously prompt DM decay into SM particles. The DM relic abundance is obtained via thermal freeze-out or, since effectively stable DM often carries baryon or lepton number, asymmetry sharing through the very operators that induce eventual DM decay. We also incorporate baryon and lepton number violation with a spurion that parameterizes hard breaking by arbitrary units. However, since proton stability precludes certain spurions, a residual symmetry persists, maintaining the cosmological stability of certain DM representations. Finally, we survey the phenomenology of effectively stable DM as manifested in probes of direct detection, indirect detection, and proton decay.Comment: 7 pages, 1 figure, 4 table

Seesaw Spectroscopy at Colliders

A low-scale neutrino seesaw may be probed or even reconstructed at colliders provided that supersymmetry is at the weak scale and the LSP is a sterile sneutrino. Because the neutrino Yukawa couplings are small, the NLSP is typically long-lived and thus a significant fraction of colored or charged NLSPs may stop in the detector material before decaying to the LSP and a charged lepton, gauge boson, or Higgs. For two-body NLSP decays, the energy spectrum of the visible decay product exhibits a monochromatic line for each sterile sneutrino which can be used to extract the sterile sneutrino masses and some or all entries of the neutrino Yukawa matrix modulo phases. Similar methods can be used to extract these parameters from the Dalitz plot in the case of three-body NLSP decays. Assuming that the sterile sneutrino and neutrino are roughly degenerate, one can confirm the existence of a neutrino seesaw by comparing these measured parameters to the observed active neutrino masses and mixing angles. Seesaw spectroscopy can also provide genuinely new information such as the value of $\theta_{13}$, the nature of the neutrino mass hierarchy, and the presence of CP conservation in the neutrino sector. We introduce a weak-scale theory of leptogenesis that can be directly tested by these techniques.Comment: 7 pages, 4 figure

(Extra)Ordinary Gauge Mediation

We study models of "(extra)ordinary gauge mediation," which consist of taking ordinary gauge mediation and extending the messenger superpotential to include all renormalizable couplings consistent with SM gauge invariance and an R-symmetry. We classify all such models and find that their phenomenology can differ significantly from that of ordinary gauge mediation. Some highlights include: arbitrary modifications of the squark/slepton mass relations, small mu and Higgsino NLSP's, and the possibility of having fewer than one effective messenger. We also show how these models lead naturally to extremely simple examples of direct gauge mediation, where SUSY and R-symmetry breaking occur not in a hidden sector, but due to the dynamics of the messenger sector itself.Comment: 50 pages, 11 figure

On positivity and roots in operator algebras

In earlier papers the second author and Charles Read have introduced and studied a new notion of positivity for operator algebras, with an eye to extending certain C*-algebraic results and theories to more general algebras. The present paper consists of complements to some facts in the just mentioned papers, concerning this notion of positivity. For example we prove a result on the numerical range of products of the roots of commuting operators with numerical range in a sector.Comment: 11 pages, to appear Integral Equations Operator Theor

Charitable organisations, the great recession and the age of austerity: longitudinal evidence for England and Wales

There has been extensive concern about the effect of recession and of subsequent public spending austerity on the voluntary sector - but a dearth of systematic sector-wide data to examine this empirically. We construct a unique longitudinal dataset, which follows through time the population of charitable organisations in England and Wales since 1999, and assess the impact of recession and austerity by placing organisations’ recent annual income within the context of longer-term trends. The results reveal the scale of the impact on charities’ incomes for the first time: since 2008 median real annual growth in income has been negative for six consecutive years, leading to sizeable cumulative real income decline over the period. Mid-sized charities, and those in more deprived local areas, have been most significantly affected, consistent with concerns about a ‘hollowing out’ of the charitable sector and about the uneven impact of austerity. However there has also been considerable variation in the fortunes of charities working in different fields of activity. The analysis in this paper helps to widen our perspective on the implications of the Great Recession and of public spending austerity for social policy

The Kahler Structure of Supersymmetric Holographic RG Flows

We study the metrics on the families of moduli spaces arising from probing with a brane the ten and eleven dimensional supergravity solutions corresponding to renormalisation group flows of supersymmetric large n gauge theory. In comparing the geometry to the physics of the dual gauge theory, it is important to identify appropriate coordinates, and starting with the case of SU(n) gauge theories flowing from N=4 to N=1 via a mass term, we demonstrate that the metric is Kahler, and solve for the Kahler potential everywhere along the flow. We show that the asymptotic form of the Kahler potential, and hence the peculiar conical form of the metric, follows from special properties of the gauge theory. Furthermore, we find the analogous Kahler structure for the N=4 preserving Coulomb branch flows, and for an N=2 flow. In addition, we establish similar properties for two eleven dimensional flow geometries recently presented in the literature, one of which has a deformation of the conifold as its moduli space. In all of these cases, we notice that the Kahler potential appears to satisfy a simple universal differential equation. We prove that this equation arises for all purely Coulomb branch flows dual to both ten and eleven dimensional geometries, and conjecture that the equation holds much more generally.Comment: 26 pages. Late

Stereolithography Cure Process Modeling Using Acrylate Resin

In this paper, a complex stereolithography (SL) cure process model is presented that incorporates transient thermal and chemical effects which influence final part shape and properties. The model incorporates photopolymerization, mass diffusion, and heat transfer. Material properties are characterized and a comprehensive kinetic model parameterized for a model compound system. SL process simulations are performed using finite element methods with the software package FEMLAB, and validated by the capability of predicting the fabricated part dimensions. A degree of cure (DOC) threshold model is proposed which can predict the cure line size within 15% error, comparing with 30% prediction error by the exposure threshold model currently used in SL. Furthermore, through the sensitivity analysis conducted by the process model presented here, the sensitive parameters are identified and the SL bath temperature, photointiator absorptivity and concentration are found to be the most sensitive factors that affect the SL fabrication results. The sensitive variables will be the focus of further research meant to improve SL process speed and resolution.Mechanical Engineerin