On the Correlation Between the Spin-Independent and Spin-Dependent Direct Detection of Dark Matter

We study the correlation between spin-independent and spin-dependent scattering in the context of MSSM neutralino dark matter for both thermal and non-thermal histories. We explore the generality of this relationship with reference to other models. We discuss why either fine-tuning or numerical coincidences are necessary for the correlation to break down. We derive upper bounds on spin-dependent scattering mediated by a Z boson.Comment: 31 pages, 6 figures, 3 appendices; v2: refs added, minor typos corrected, journal versio

The mortality of cellulose fiber production workers

This dissertation examines the relation between occupational exposure to the solvent methylene chloride and mortality in a cohort of cellulose fiber production workers. The first paper, entitled The Mortality of Cellulose Fiber Production Workers, presents the main results of the mortality follow-up of the cellulose fiber workers cohort through September 1, 1986. Mortality from neoplastic and non-neoplastic disease among cellulose fiber production workers is compared to that of the U.S. and local (county level) populations, while controlling for the effects of gender, race, calendar period, and age. Mortality from cancers of the lung, breast, and pancreas, and ischemic heart disease was less than expected. Excess mortality was observed for melanoma of the skin, cancer of the buccal cavity and pharynx, tumors of the liver and biliary tract, and accidental deaths. Three deaths from cancer of the bile ducts were observed (3 observed, 0.15 expected, SMR=20). This is the first known report of an association between exposure to methylene chloride and cancer of the bile ducts. [TRUNCATED

Asymmetric Dark Matter from a GeV Hidden Sector

Asymmetric Dark Matter (ADM) models relate the dark matter density to the baryon asymmetry, so that a natural mass scale for ADM is around a few GeV. In existing models of ADM, this mass scale is unexplained; here we generate this GeV scale for dark matter (DM) from the weak scale via gauge kinetic mixing with a new Abelian dark force. In addition, this dark sector provides an efficient mechanism for suppressing the symmetric abundance of DM through annihilations to the dark photon. We augment this sector with a higher dimensional operator responsible for communicating the baryon asymmetry to the dark sector. Our framework also provides DM candidate for gauge mediation models. It results in a direct detection cross section of interest for current experiments: sigma less than or similar to 10^{-42} cm^2 for DM masses in the range 1 - 15 GeV.Comment: 21 pages, 4 figure

Supersymmetric Baryogenesis from Exotic Quark Decays

In a simple extension of the minimal supersymmetric standard model, out-of-equilibrium decays of TeV scale exotic vector-like squarks may generate the baryon asymmetry of the universe. Baryon number and CP violation are present in the superpotential, so this mechanism does not rely on CP violation in supersymmetry breaking parameters. We discuss phenomenological constraints on the model as well as potential signals for the Large Hadron Collider and electronic dipole moment experiments. A variation on the TeV scale model allows the exotic squarks to be the messengers of gauge mediated supersymmetry breaking.Comment: 28 pages, 7 figures, 2 appendices, v2: typos corrected, results unchange

Transsylvian selective amygdalohippocampectomy for treatment of medial temporal lobe epilepsy: Surgical technique and operative nuances to avoid complications

Background: A number of different surgical techniques are effective for treatment of drug-resistant medial temporal lobe epilepsy. Of these, transsylvian selective amygdalohippocampectomy (SA), which was originally developed to maximize temporal lobe preservation, is arguably the most technically demanding to perform. Recent studies have suggested that SA may result in better neuropsychological outcomes with similar postoperative seizure control as standard anterior temporal lobectomy, which involves removal of the lateral temporal neocortex. Methods: In this article, the authors describe technical nuances to improve the safety of SA. Results: Wide sylvian fissure opening and use of neuronavigation allows an adequate exposure of the amygdala and hippocampus through a corticotomy within the inferior insular sulcus. Avoidance of rigid retractors and careful manipulation and mobilization of middle cerebral vessels will minimize ischemic complications. Identification of important landmarks during amygdalohippocampectomy, such as the medial edge of the tentorium and the third nerve within the intact arachnoid membranes covering the brainstem, further avoids operator disorientation. Conclusion: SA is a safe technique for resection of medial temporal lobe epileptogenic foci leading to drug-resistant medial temporal lobe epilepsy

Cushing's ulcer: Further reflections

BACKGROUND: Brain tumors, traumatic head injury, and other intracranial processes including infections, can cause increased intracranial pressure and lead to overstimulation of the vagus nerve. As a result, increased secretion of gastric acid may occur which leads to gastro-duodenal ulcer formation known as Cushing's ulcer. METHODS: A review of original records of Dr. Harvey Cushing's patients suffering from gastro-duodenal ulcers was performed followed by a discussion of the available literature. We also reviewed the clinical records of the patients never reported by Cushing to gain his perspective in describing this phenomenon. Dr. Cushing was intrigued to investigate gastro-duodenal ulcers as he lost patients to acute gastrointestinal perforations following successful brain tumor operations. It is indeed ironic that Harvey Cushing developed a gastro-duodenal ulcer in his later years with failing health. RESULTS: Clinically shown by Cushing's Yale Registry, a tumor or lesion can disrupt this circuitry, leading to gastroduodenal ulceration. Cushing said that it was "reasonable to believe that the perforations following posterior fossa cerebellar operations were produced in like fashion by an irritative disturbance either of fiber tracts or vagal centers in the brain stem." CONCLUSION: Harvey Cushing's pioneering work depicted in his Yale registry serves as a milestone for continuing research that can further discern this pathway

sparsegl: An R Package for Estimating Sparse Group Lasso

The sparse group lasso is a high-dimensional regression technique that is useful for problems whose predictors have a naturally grouped structure and where sparsity is encouraged at both the group and individual predictor level. In this paper we discuss a new R package for computing such regularized models. The intention is to provide highly optimized solution routines enabling analysis of very large datasets, especially in the context of sparse design matrices.Comment: 18 pages, 9 figures, 1 tabl