Bounds of the rank of the Mordell-Weil group of jacobians of hyperelliptic curves

In this article we extend work of Shanks and Washington on cyclic extensions, and elliptic curves associated to the simplest cubic fields. In particular, we give families of examples of hyperelliptic curves $C: y^2=f(x)$ defined over $\mathbb{Q}$, with $f(x)$ of degree $p$, where $p$ is a Sophie Germain prime, such that the rank of the Mordell--Weil group of the jacobian $J/\mathbb{Q}$ of $C$ is bounded by the genus of $C$ and the $2$-rank of the class group of the (cyclic) field defined by $f(x)$, and exhibit examples where this bound is sharp.Comment: 22 pages, To appear in J. Th\'eor. Nombres Bordeau

Stochastic programming in energy

We give the reader a tour of good energy optimization models that explicitly deal with uncertainty. The uncertainty usually stems from unpredictability of demand and/or prices of energy, or from resource availability and prices. Since most energy investments or operations involve irreversible decisions, a stochastic programming approach is meaningful. Many of the models deal with electricity investments and operations, but some oil and gas applications are also presented. We consider both traditional cost minimization models and newer models that reflect industry deregulation processes. The oldest research coincides with the birth of linear programming, and most models within the market paradigm have not yet found their final form.stochastic programming, energy, regulated markets, deregulation, uncertainty, electricity, natural gas, oil

Hierarchical Multiscale Modeling to Inform Continuum Constitutive Models of Soils

The behavior of soils is fundamentally the combined interactions between billions and billions of individual particles and particle matrices. For computational tractability and despite this fact, many soil models assume the material is a continuum essentially averaging the inter-particle interactions to predict the behavior of the bulk material. In recent years, multiscale modeling techniques have been developed to reintroduce the effect of the grain-scale interactions to help model situations where the continuum assumption fails, such as shear band development in triaxial tests or soil disaggregation under blast loading. One of such multiscale models called hierarchical upscaling, or global-local analysis, model the problem domain using typical continuum-based approaches, but replace the continuum constitutive model with grain-scale models that represent the microstructure at the given point. The deformation of the material is solved via the continuum-scale boundary value problem, which is then passed to the grain-scale as boundary conditions on these representative volume elements (RVEs). The RVEs are then allowed to deform, and the resulting stress is passed back to the continuum scale. Three hierarchical multiscale models were developed to model a series of experimental results on dry Colorado Mason Sand. In all three models, the grain-scale was modeled using the discrete element method through a code called ellip3D. Ellip3D models of dry Colorado Mason Sand were integrated with three continuum models: a one dimensional, finite strain finite element model with full dynamics (1D FEM-DEM model), a one dimensional material point method implementation (1D MPM-DEM model), and a two dimensional, small strain, axisymmetric finite element model (2Daxi FEM-DEM model). The one dimensional models were used to model a split Hopkinson pressure bar test and the two dimensional model was used to model two triaxial tests. With the inclusion of a particle fracture model, the results of the split Hopkinson pressure bar experiment were reasonably well replicated; however, the 2Daxi FEM-DEM model over-predicts the stress response of the triaxial tests. Regardless, to the author's knowledge, the results herein presented are the first attempt to directly compare FEM-DEM global-local analysis models to experimental data. Also, the MPM-DEM implementation is a novel extension of other FEM-DEM models to a meshfree numerical methods

Hierarchical Multiscale Modeling to Inform Continuum Constitutive Models of Soils

The behavior of soils is fundamentally the combined interactions between billions and billions of individual particles and particle matrices. For computational tractability and despite this fact, many soil models assume the material is a continuum essentially averaging the inter-particle interactions to predict the behavior of the bulk material. In recent years, multiscale modeling techniques have been developed to reintroduce the effect of the grain-scale interactions to help model situations where the continuum assumption fails, such as shear band development in triaxial tests or soil disaggregation under blast loading. One of such multiscale models called hierarchical upscaling, or global-local analysis, model the problem domain using typical continuum-based approaches, but replace the continuum constitutive model with grain-scale models that represent the microstructure at the given point. The deformation of the material is solved via the continuum-scale boundary value problem, which is then passed to the grain-scale as boundary conditions on these representative volume elements (RVEs). The RVEs are then allowed to deform, and the resulting stress is passed back to the continuum scale. Three hierarchical multiscale models were developed to model a series of experimental results on dry Colorado Mason Sand. In all three models, the grain-scale was modeled using the discrete element method through a code called ellip3D. Ellip3D models of dry Colorado Mason Sand were integrated with three continuum models: a one dimensional, finite strain finite element model with full dynamics (1D FEM-DEM model), a one dimensional material point method implementation (1D MPM-DEM model), and a two dimensional, small strain, axisymmetric finite element model (2Daxi FEM-DEM model). The one dimensional models were used to model a split Hopkinson pressure bar test and the two dimensional model was used to model two triaxial tests. With the inclusion of a particle fracture model, the results of the split Hopkinson pressure bar experiment were reasonably well replicated; however, the 2Daxi FEM-DEM model over-predicts the stress response of the triaxial tests. Regardless, to the author's knowledge, the results herein presented are the first attempt to directly compare FEM-DEM global-local analysis models to experimental data. Also, the MPM-DEM implementation is a novel extension of other FEM-DEM models to a meshfree numerical methods

Liquid state properties from first principles DFT calculations: Static properties

In order to test the Vibration-Transit (V-T) theory of liquid dynamics, ab initio density functional theory (DFT) calculations of thermodynamic properties of Na and Cu are performed and compared with experimental data. The calculations are done for the crystal at T = 0 and T_m, and for the liquid at T_m. The key theoretical quantities for crystal and liquid are the structural potential and the dynamical matrix, both as function of volume. The theoretical equations are presented, as well as details of the DFT computations. The properties compared with experiment are the equilibrium volume, the isothermal bulk modulus, the internal energy and the entropy. The agreement of theory with experiment is uniformly good. Our primary conclusion is that the application of DFT to V-T theory is feasible, and the resulting liquid calculations achieve the same level of accuracy as does ab initio lattice dynamics for crystals. Moreover, given the well established reliability of DFT, the present results provide a significant confirmation of V-T theory itself.Comment: 9 pages, 3 figures, 5 tables, edited to more closely match published versio

Frequency of instrument, environment, and laboratory technologist contamination during routine diagnostic testing of infectious specimens

ABSTRACT Laboratory testing to support the care of patients with highly infectious diseases may pose a risk for laboratory workers. However, data on the risk of virus transmission during routine laboratory testing conducted using standard personal protective equipment (PPE) are sparse. Our objective was to measure laboratory contamination during routine analysis of patient specimens. Remnant specimens were spiked with the nonpathogenic bacteriophage MS2 at 1.0 × 10 7 PFU/ml, and contamination was assessed using reverse transcriptase PCR (RT-PCR) for MS2. Specimen containers were exteriorly coated with a fluorescent powder to enable the visualization of gross contamination using UV light. Testing was performed by two experienced laboratory technologists using standard laboratory PPE and sample-to-answer instrumentation. Fluorescence was noted on the gloves, bare hands, and laboratory coat cuffs of the laboratory technologist in 36/36 (100%), 13/36 (36%), and 4/36 (11%) tests performed, respectively. Fluorescence was observed in the biosafety cabinet (BSC) in 8/36 (22%) tests, on test cartridges/devices in 14/32 (44%) tests, and on testing accessory items in 29/32 (91%) tests. Fluorescence was not observed on or in laboratory instrumentation or adjacent surfaces. In contrast to fluorescence detection, MS2 detection was infrequent (3/286 instances [1%]) and occurred during test setup for the FilmArray instrument and on FilmArray accessory equipment. The information from this study may provide opportunities for the improvement of clinical laboratory safety practices so as to reduce the risk of pathogen transmission to laboratory workers. </jats:p

Assessment of healthcare worker protocol deviations and self-contamination during personal protective equipment donning and doffing

OBJECTIVETo evaluate healthcare worker (HCW) risk of self-contamination when donning and doffing personal protective equipment (PPE) using fluorescence and MS2 bacteriophage.DESIGNProspective pilot study.SETTINGTertiary-care hospital.PARTICIPANTSA total of 36 HCWs were included in this study: 18 donned/doffed contact precaution (CP) PPE and 18 donned/doffed Ebola virus disease (EVD) PPE.INTERVENTIONSHCWs donned PPE according to standard protocols. Fluorescent liquid and MS2 bacteriophage were applied to HCWs. HCWs then doffed their PPE. After doffing, HCWs were scanned for fluorescence and swabbed for MS2. MS2 detection was performed using reverse transcriptase PCR. The donning and doffing processes were videotaped, and protocol deviations were recorded.RESULTSOverall, 27% of EVD PPE HCWs and 50% of CP PPE HCWs made ≥1 protocol deviation while donning, and 100% of EVD PPE HCWs and 67% of CP PPE HCWs made ≥1 protocol deviation while doffing (P=.02). The median number of doffing protocol deviations among EVD PPE HCWs was 4, versus 1 among CP PPE HCWs. Also, 15 EVD PPE protocol deviations were committed by doffing assistants and/or trained observers. Fluorescence was detected on 8 EVD PPE HCWs (44%) and 5 CP PPE HCWs (28%), most commonly on hands. MS2 was recovered from 2 EVD PPE HCWs (11%) and 3 CP PPE HCWs (17%).CONCLUSIONSProtocol deviations were common during both EVD and CP PPE doffing, and some deviations during EVD PPE doffing were committed by the HCW doffing assistant and/or the trained observer. Self-contamination was common. PPE donning/doffing are complex and deserve additional study.Infect Control Hosp Epidemiol 2017;38:1077–1083</jats:sec