Families of Quintic Calabi-Yau 3-Folds with Discrete Symmetries

At special loci in their moduli spaces, Calabi-Yau manifolds are endowed with discrete symmetries. Over the years, such spaces have been intensely studied and have found a variety of important applications. As string compactifications they are phenomenologically favored, and considerably simplify many important calculations. Mathematically, they provided the framework for the first construction of mirror manifolds, and the resulting rational curve counts. Thus, it is of significant interest to investigate such manifolds further. In this paper, we consider several unexplored loci within familiar families of Calabi-Yau hypersurfaces that have large but unexpected discrete symmetry groups. By deriving, correcting, and generalizing a technique similar to that of Candelas, de la Ossa and Rodriguez-Villegas, we find a calculationally tractable means of finding the Picard-Fuchs equations satisfied by the periods of all 3-forms in these families. To provide a modest point of comparison, we then briefly investigate the relation between the size of the symmetry group along these loci and the number of nonzero Yukawa couplings. We include an introductory exposition of the mathematics involved, intended to be accessible to physicists, in order to make the discussion self-contained.Comment: 54 pages, 3 figure

A shortage of health information management professionals: How would we know?

The introduction of computers, the expansion of health insurance coverage through employers and government programs, and the increased use of personal health information have created a demand for a new breed of qualified medical record and health information personnel. The health information management workforce, which is entrusted with accurately coding, maintaining, storing, managing, analyzing, and disseminating all personal health information created from health care encounters, is reportedly in short supply. Given the complexity in defining and enumerating the profession, it is challenging to determine if such a shortage exists. There is a lack of uniformity across scope of practice, job titles, educational paths, and credentials. We report selected findings from a study of the health information management profession in North Carolina illustrating the methodologic problems encountered when measuring the supply and demand of this workforce. A case is made that greater standardization across these multiple facets of the profession would be beneficial to the workforce, and we offer recommendations on how this could be accomplished

EYM equations in the presence of q-stars

We study Einstein-Yang-Mills equations in the presence of gravitating non-topological soliton field configurations, of q-ball type. We produce numerical solutions, stable with respect to gravitational collapse and to fission into free particles, and we study the effect of the field strength and the eigen-frequency to the soliton parameters. We also investigate the formation of such soliton stars when the spacetime is asymptotically anti de Sitter.Comment: 11 pages, to appear in Phys. Rev.

The Fall of Stringy de Sitter

Kachru, Kallosh, Linde, & Trivedi recently constructed a four-dimensional de Sitter compactification of IIB string theory, which they showed to be metastable in agreement with general arguments about de Sitter spacetimes in quantum gravity. In this paper, we describe how discrete flux choices lead to a closely-spaced set of vacua and explore various decay channels. We find that in many situations NS5-brane meditated decays which exchange NSNS 3-form flux for D3-branes are comparatively very fast.Comment: 35 pp (11 pp appendices), 5 figures, v3. fixed minor typo

Suicide typologies among Medicaid beneficiaries, North Carolina 2014–2017

Background: There is a well-established need for population-based screening strategies to identify people at risk of suicide. Because only about half of suicide decedents are ever diagnosed with a behavioral health condition, it may be necessary for providers to consider life circumstances that may also put individuals at risk. This study described the alignment of medical diagnoses with life circumstances by identifying suicide typologies among decedents. Demographics, stressful life events, suicidal behavior, perceived and diagnosed health problems, and suicide method contributed to the typologies. Methods: This study linked North Carolina Medicaid and North Carolina Violent Death Reporting System (NC-VDRS) data for analysis in 2020. For suicide decedents from 2014 to 2017 aged 25–54 years, we analyzed 12 indicators of life circumstances from NC-VDRS and 6 indicators from Medicaid claims, using a latent class model. Separate models were developed for men and women. Results: Most decedents were White (88.3%), with a median age of 41, and over 70% had a health care visit in the 90 days prior to suicide. Two typologies were identified in both males (n = 175) and females (n = 153). Both typologies had similar profiles of life circumstances, but one had high probabilities of diagnosed behavioral health conditions (45% of men, 71% of women), compared to low probabilities in the other (55% of men, 29% of women). Black beneficiaries and men who died by firearm were over-represented in the less-diagnosed class, though estimates were imprecise (odds ratio for Black men: 3.1, 95% confidence interval: 0.8, 12.4; odds ratio for Black women: 5.0, 95% confidence interval: 0.9, 31.2; odds ratio for male firearm decedents: 1.6, 95% confidence interval: 0.7, 3.4). Conclusions: Nearly half of suicide decedents have a typology characterized by low probability of diagnosis of behavioral health conditions. Suicide screening could likely be enhanced using improved indicators of lived experience and behavioral health

Association Between Medical Diagnoses and Suicide in a Medicaid Beneficiary Population, North Carolina 2014–2017

Background: Firearms are used in about half of U.S. suicides. This study investigated how various medical diagnoses are associated with firearm and nonfirearm suicide. Methods: We used a case–control design including n = 691 North Carolina Medicaid beneficiaries who died from suicide between 1 January 2014 and 31 December 2017 as cases. We selected a total of n = 68,682 controls (~1:100 case–control ratio from North Carolina Medicaid member files using incidence density sampling methods). We linked Medicaid claims to the North Carolina Violent Death Reporting System to ascertain suicide and means (firearm or nonfirearm). We matched cases and controls on number of months covered by Medicaid over the past 36 months. Analyses adjusted for sex, race, age, Supplemental Security Income status, the Charlson Comorbidity Index, and frequency of health care encounters. Results: The case–control odds ratios for any mental health disorder were 4.2 (95% confidence interval [CI]: 3.3, 5.2) for nonfirearm suicide and 2.2 (95% CI: 1.7, 2.9) for firearm suicide. There was effect measure modification by sex and race. Behavioral health diagnoses were more strongly associated with nonfirearm suicides than firearm suicide in men but did not differ substantially in women. The association of mental health and substance use diagnoses with suicides appeared to be weaker in Blacks (vs. non-Blacks), but the estimates were imprecise. Conclusion: Behavioral health diagnoses are important indicators of risk of suicide. However, these associations differ by means of suicide and sex, and associations for firearm-related suicide are weaker in men than women

Bouncing back from failure: Entrepreneurial resilience and the internationalization of subsequent ventures created by serial entrepreneurs

This paper examines the impact over international propensity of past negative entrepreneurial experience for those who re-enter into entrepreneurial activity; referred to as resilient serial entrepreneurs. We first hypothesize on the effects over entrepreneurial re-entry that such negative past experience may have and highlight the link between the past entrepreneurial experience of resilient entrepreneurs and their subsequent propensity towards international markets. Building on insights from the generative experiential learning process of entrepreneurial activity and from cognition theories, we propose that resilient entrepreneurs who re-enter business despite having faced negative entrepreneurial experiences in the past benefit from enriched cognitive schemas leading them to greater export propensity. The proposed hypotheses are tested on a unique sample drawn from a Spanish adult population survey. Results from the sequential deductive triangulation analysis (QUAN -> qual) reveal that practical experience is an essential prerequisite for entrepreneurial learning, and that the resilience of those with negative entrepreneurial experience induces the generative entrepreneurial learning especially suitable for subsequent internationally oriented ventures.Peer ReviewedPreprin

Type IIB Solutions with Interpolating Supersymmetries

We study type IIB supergravity solutions with four supersymmetries that interpolate between two types widely considered in the literature: the dual of Becker and Becker's compactifications of M-theory to 3 dimensions and the dual of Strominger's torsion compactifications of heterotic theory to 4 dimensions. We find that for all intermediate solutions the internal manifold is not Calabi-Yau, but has SU(3) holonomy in a connection with a torsion given by the 3-form flux. All 3-form and 5-form fluxes, as well as the dilaton, depend on one function appearing in the supersymmetry spinor, which satisfies a nonlinear differential equation. We check that the fields corresponding to a flat bound state of D3/D5-branes lie in our class of solutions. The relations among supergravity fields that we derive should be useful in studying new gravity duals of gauge theories, as well as possibly compactifications.Comment: 27pp, v2 REVTeX4, typographical fixes and minor clarifications, v3 added ref, modified discussion of RR axion slightl

Hierarchies from Fluxes in String Compactifications

Warped compactifications with significant warping provide one of the few known mechanisms for naturally generating large hierarchies of physical scales. We demonstrate that this mechanism is realizable in string theory, and give examples involving orientifold compactifications of IIB string theory and F-theory compactifications on Calabi-Yau four-folds. In each case, the hierarchy of scales is fixed by a choice of RR and NS fluxes in the compact manifold. Our solutions involve compactifications of the Klebanov-Strassler gravity dual to a confining N=1 supersymmetric gauge theory,and the hierarchy reflects the small scale of chiral symmetry breaking in the dual gauge theory.Comment: 35 pages. v2: minor eqn. and reference change

de Sitter Vacua in String Theory

We outline the construction of metastable de Sitter vacua of type IIB string theory. Our starting point is highly warped IIB compactifications with nontrivial NS and RR three-form fluxes. By incorporating known corrections to the superpotential from Euclidean D-brane instantons or gaugino condensation, one can make models with all moduli fixed, yielding a supersymmetric AdS vacuum. Inclusion of a small number of anti-D3 branes in the resulting warped geometry allows one to uplift the AdS minimum and make it a metastable de Sitter ground state. The lifetime of our metastable de Sitter vacua is much greater than the cosmological timescale of 10^10 years. We also prove, under certain conditions, that the lifetime of dS space in string theory will always be shorter than the recurrence time.Comment: 12 pages, 2 figs, added comments on the thin wall approximation to tunnelin