Global Spinors and Orientable Five-Branes

Fermion fields on an M-theory five-brane carry a representation of the double cover of the structure group of the normal bundle. It is shown that, on an arbitrary oriented Lorentzian six-manifold, there is always an Sp(2) twist that allows such spinors to be defined globally. The vanishing of the arising potential obstructions does not depend on spin structure in the bulk, nor does the six-manifold need to be spin or spin-C. Lifting the tangent bundle to such a generalised spin bundle requires picking a generalised spin structure in terms of certain elements in the integral and modulo-two cohomology of the five-brane world-volume in degrees four and five, respectively.Comment: 18 pages, LaTeX; v2: version to appear in JHE

Premenopausal gynecologic surgery and survival among black and white women with breast cancer

Purpose: In the United States, hysterectomies and oophorectomies are frequently performed before menopause for benign conditions. The procedures are associated with reduced breast cancer-specific mortality among White women. The relationship between premenopausal gynecologic surgery and mortality in Black women with breast cancer is unknown. Methods: This investigation used incident invasive cases of breast cancer from Phases 1 and 2 of the Carolina Breast Cancer Study a population-based study that recruited Black and White women in North Carolina between 1993 and 2001. Premenopausal gynecologic surgery was operationalized in three categories: no surgery; hysterectomy with bilateral oophorectomy; hysterectomy with conservation of ≥ 1 ovary. Mortality was ascertained using the National Death Index, last updated in 2016. Multivariable-adjusted Cox Proportional Hazard Models were used to estimate the effect of premenopausal surgery on breast cancer-specific and all-cause mortality Results: Hysterectomy with bilateral oophorectomy was associated with reduced breast cancer-specific mortality (HR 0.68; 95% CI 0.49, 0.96). White and Black women had a similar reduction in breast cancer-specific mortality. (HR among white: 0.66; 95% CI 0.43, 1.02), (HR among Black: 0.67; 95% CI 0.37, 1.21). Conclusions: There was a similar reduction in breast cancer-specific mortality following premenopausal, pre-diagnosis hysterectomy with bilateral oophorectomy across both Black and White women

Trends in surgical treatment of early-stage breast cancer reveal decreasing mastectomy use between 2003 and 2016 by age, race, and rurality

Purpose: To examine trends in the surgical treatment of breast cancer by age, rurality, and among Black women in a populous, racially diverse, state in the Southeastern United States of America. Methods: We identified women diagnosed with localized or regional breast cancer between 2003 and 2016 in the North Carolina Central Cancer Registry (n = 86,776). Using Joinpoint regression we evaluated the average annual percentage change in proportion of women treated with mastectomy versus breast-conserving surgery overall, by age group, among Black women, and for women residing in rural areas. Results: Overall, the rate of mastectomy usage in the population declined 2.5% per year between 2003 and 2016 (95% CI − 3.2, − 1.7). Over this same time interval, breast-conserving surgery increased by 1.6% per year (95% CI 0.9, 2.2). These temporal trends in surgery were also observed among Black women and rural residing women. Trends in surgery type varied by age group: mastectomy declined over time among women > 50 years, but not among women aged 18–49 at diagnosis. Discussion: In contrast to national studies that reported increasing use of mastectomy, we found declining mastectomy rates in the early 2000s in a Southern US state with a racially and geographically diverse population. These decreasing trends were consistent among key subgroups affected by cancer inequities, including Black and White rural women

Validity of breast cancer surgery treatment information in a state-based cancer registry

Purpose: Surgery is an important part of early stage breast cancer treatment that affects overall survival. Many studies of surgical treatment of breast cancer rely on data sources that condition on continuous insurance coverage or treatment at specified facilities and thus under-sample populations especially affected by cancer care inequities including the uninsured and rural populations. Statewide cancer registries contain data on first course of cancer treatment for all patients diagnosed with cancer but the accuracy of these data are uncertain. Methods: Patients diagnosed with stage I–III breast cancer between 2003 and 2016 were identified using the North Carolina Central Cancer Registry and linked to Medicaid, Medicare, and private insurance claims. We calculated the sensitivity, specificity, positive predictive value, negative predictive value, and Kappa statistics for receipt of surgery and type of surgery (breast conserving surgery or mastectomy) using the insurance claims as the presumed gold standard. Analyses were stratified by race, insurance type, and rurality. Results: Of 26,819 patients who met eligibility criteria, 23,125 were identified as having surgery in both the claims and registry for a sensitivity of 97.9% (95% CI 97.8%, 98.1%). There was also strong agreement for surgery type between the cancer registry and the insurance claims (Kappa: 0.91). Registry treatment data validity was lower for Medicaid insured patients than for Medicare and commercially insured patients. Conclusions: Cancer registry treatment data reliably identified receipt and type of breast cancer surgery. Cancer registries are an important source of data for understanding cancer care in underrepresented populations

Photoionization of ultracold and Bose-Einstein condensed Rb atoms

Photoionization of a cold atomic sample offers intriguing possibilities to observe collective effects at extremely low temperatures. Irradiation of a rubidium condensate and of cold rubidium atoms within a magneto-optical trap with laser pulses ionizing through 1-photon and 2-photon absorption processes has been performed. Losses and modifications in the density profile of the remaining trapped cold cloud or the remaining condensate sample have been examined as function of the ionizing laser parameters. Ionization cross-sections were measured for atoms in a MOT, while in magnetic traps losses larger than those expected for ionization process were measured.Comment: 9 pages, 7 figure

U(2)-like Flavor Symmetries and Approximate Bimaximal Neutrino Mixing

Models involving a U(2) flavor symmetry, or any of a number of its non-Abelian discrete subgroups, can explain the observed hierarchy of charged fermion masses and CKM angles. It is known that a large neutrino mixing angle connecting second and third generation fields may arise via the seesaw mechanism in these models, without a fine tuning of parameters. Here we show that it is possible to obtain approximate bimaximal mixing in a class of models with U(2)-like Yukawa textures. We find a minimal form for Dirac and Majorana neutrino mass matrices that leads to two large mixing angles, and show that our result can quantitatively explain atmospheric neutrino oscillations while accommodating the favored, large angle MSW solution to the solar neutrino problem. We demonstrate that these textures can arise in models by presenting a number of explicit examples.Comment: 20 pages RevTex4, 2 figure

Optimal inference with suboptimal models:Addiction and active Bayesian inference

When casting behaviour as active (Bayesian) inference, optimal inference is defined with respect to an agent's beliefs - based on its generative model of the world. This contrasts with normative accounts of choice behaviour, in which optimal actions are considered in relation to the true structure of the environment - as opposed to the agent's beliefs about worldly states (or the task). This distinction shifts an understanding of suboptimal or pathological behaviour away from aberrant inference as such, to understanding the prior beliefs of a subject that cause them to behave less 'optimally' than our prior beliefs suggest they should behave. Put simply, suboptimal or pathological behaviour does not speak against understanding behaviour in terms of (Bayes optimal) inference, but rather calls for a more refined understanding of the subject's generative model upon which their (optimal) Bayesian inference is based. Here, we discuss this fundamental distinction and its implications for understanding optimality, bounded rationality and pathological (choice) behaviour. We illustrate our argument using addictive choice behaviour in a recently described 'limited offer' task. Our simulations of pathological choices and addictive behaviour also generate some clear hypotheses, which we hope to pursue in ongoing empirical work

Biochemical Responses of Asparagus to Controlled Atmosphere Storage at 20 Degrees C

In seeking to understand the beneficial effects of controlled atmosphere (CA) storage at 20 degrees C on asparagus (Asparagus officinalis L.), biochemical responses of spear tips stored in air were compared with those of spears stored under CA (2% 02, 10% CO2). CA storage prevented the rapid loss of sucrose, increased acid invertase activity and asparagine accumulation observed in the tips of spears stored in air. CA storage also delayed changes in the levels of glutamine, malic, citric and fumaric acids, compared with those in tips of air-stored spears. Elongation observed in water-fed spears in air was reduced by CA. It is proposed that CA acted by depressing metabolism to such an extent that sucrose levels were maintained in the spear tip and this, in turn, prevented the cascade of metabolic events that contribute to spear deterioration in air