High Speed Phase-Resolved 2-d UBV Photometry of the Crab pulsar

We report a phase-resolved photometric and morphological analysis of UBV data of the Crab pulsar obtained with the 2-d TRIFFID high speed optical photometer mounted on the Russian 6m telescope. By being able to accurately isolate the pulsar from the nebular background at an unprecedented temporal resolution (1 \mu s), the various light curve components were accurately fluxed via phase-resolved photometry. Within the $UBV$ range, our datasets are consistent with the existing trends reported elsewhere in the literature. In terms of flux and phase duration, both the peak Full Width Half Maxima and Half Width Half Maxima decrease as a function of photon energy. This is similarly the case for the flux associated with the bridge of emission. Power-law fits to the various light curve components are as follows; \alpha = 0.07 \pm 0.19 (peak 1), \alpha = -0.06 \pm 0.19 (peak 2) and \alpha = -0.44 \pm 0.19 (bridge) - the uncertainty here being dominated by the integrated CCD photometry used to independently reference the TRIFFID data. Temporally, the main peaks are coincident to \le 10 \mu s although an accurate phase lag with respect to the radio main peak is compromised by radio timing uncertainties. The plateau on the Crab's main peak was definitively determined to be \leq 55 \mu s in extent and may decrease as a function of photon energy. There is no evidence for non-stochastic activity over the light curves or within various phase regions, nor is there evidence of anything akin to the giant pulses noted in the radio. Finally, there is no evidence to support the existence of a reported 60 second modulation suggested to be as a consequence of free precession.Comment: 13 pages, 12 figures, accepted for publication in Astronomy & Astrophysic

Facile O-atom insertion into C-C and C-H bonds by a trinuclear copper complex designed to harness a singlet oxene

Two trinuclear copper [CuICuICuI(L)]1+ complexes have been prepared with the multidentate ligands (L) 3,3'-(1,4-diazepane-1,4-diyl)bis(1-((2-(dimethylamino)ethyl)(methyl)amino)propan-2-ol) (7-Me) and (3,3'-(1,4-diazepane-1,4-diyl)bis(1-((2-(diethylamino) ethyl)(ethyl) amino)propan-2-ol) (7-Et) as models for the active site of the particulate methane monooxygenase (pMMO). The ligands were designed to form the proper spatial and electronic geometry to harness a "singlet oxene," according to the mechanism previously suggested by our laboratory. Consistent with the design strategy, both [CuICuICuI(L)]1+ reacted with dioxygen to form a putative bis(µ3-oxo)CuIICuIICuIII species, capable of facile O-atom insertion across the central C-C bond of benzil and 2,3-butanedione at ambient temperature and pressure. These complexes also catalyze facile O-atom transfer to the C-H bond of CH3CN to form glycolonitrile. These results, together with our recent biochemical studies on pMMO, provide support for our hypothesis that the hydroxylation site of pMMO contains a trinuclear copper cluster that mediates C-H bond activation by a singlet oxene mechanism

Quantifying the impact of dissimilar HPV vaccination uptake among Manitoban school girls by ethnicity using a transmission dynamic model

BACKGROUND: Gardasil, a human papillomavirus (HPV) vaccine, began among grade 6 girls in Manitoba, Canada in 2008. In Manitoba, there is evidence that First Nations, Metis, and Inuit women (FNMI) have higher HPV prevalence, lower invasive cervical cancer (ICC) screening, and higher ICC incidence than all other Manitoban (AOM) women. We developed a mathematical model to assess the plausible impact of unequal vaccination coverage among school girls on future cervical cancer incidence. METHODS: We fit model estimated HPV prevalence and ICC incidence to corresponding empirical estimates. We used the fitted model to evaluate the impact of varying levels of vaccination uptake by FNMI status on future ICC incidence, assuming cervical screening uptake among FNMI and AOM women remained unchanged. RESULTS: Depending on vaccination coverage, estimated ICC incidence by 2059 ranged from 15% to 68% lower than if there were no vaccination. The level of cross-ethnic sexual mixing influenced the impact that vaccination rates among FNMI has on ICC incidence among AOM, and vice versa. The same level of AOM vaccination could result in ICC incidence that differs by up to 10%, depending on the level of FNMI vaccination. Similarly, the same level of FNMI vaccination could result in ICC incidence that differs by almost 40%, depending on the level of AOM vaccination. CONCLUSIONS: If we are unable to equalize vaccination uptake among all school girls, policy makers should prepare for higher levels of cervical cancer than would occur under equal vaccination uptak

The evolution of bits and bottlenecks in a scientific workflow trying to keep up with technology: Accelerating 4D image segmentation applied to nasa data

In 2016, a team of earth scientists directly engaged a team of computer scientists to identify cyberinfrastructure (CI) approaches that would speed up an earth science workflow. This paper describes the evolution of that workflow as the two teams bridged CI and an image segmentation algorithm to do large scale earth science research. The Pacific Research Platform (PRP) and The Cognitive Hardware and Software Ecosystem Community Infrastructure (CHASE-CI) resources were used to significantly decreased the earth science workflow's wall-clock time from 19.5 days to 53 minutes. The improvement in wall-clock time comes from the use of network appliances, improved image segmentation, deployment of a containerized workflow, and the increase in CI experience and training for the earth scientists. This paper presents a description of the evolving innovations used to improve the workflow, bottlenecks identified within each workflow version, and improvements made within each version of the workflow, over a three-year time period

Lysis mediated by T cells and restricted by H-2 antigen of target cells infected with vaccinia virus

VARIOUS virus infections lead to the formation of cytotoxic lymphocytes (CL), which are capable of killing virus-infected target cells1−4. Specific lysis of target cells infected with 51Cr-labelled vaccinia virus could be observed when investigating the cell-mediated cytotoxic reaction to vaccinia virus5; the CL could be characterised as a T cell. The sensitised lymphocytes from C3H mice could only kill syngeneic L929 cells infected with vaccinia virus, whereas lysis by sensitised lymphocytes derived from DBA/2 mice was restricted to the syngeneic infected mastocytoma P815X2 cells. In the lymphocytic choriomeningitis infection the target cell lysis was shown to be restricted by H-2 antigen6. We report here experiments with primary fibroblasts of the mouse strains C3H, DBA/2 and the (C3H DBA/2)F1 generation were designed to affirm that the effector phase of virus-specific lysis of target cells mediated by T cells is restricted by H-2 antigen even in the vaccinia virus infection. Further experiments with H-2 alloantisera were performed to indicate the close local relationship between H-2 antigens and viral surface antigens

Simultaneous Absolute Timing of the Crab Pulsar at Radio and Optical Wavelengths

The Crab pulsar emits across a large part of the electromagnetic spectrum. Determining the time delay between the emission at different wavelengths will allow to better constrain the site and mechanism of the emission. We have simultaneously observed the Crab Pulsar in the optical with S-Cam, an instrument based on Superconducting Tunneling Junctions (STJs) with $\mu$s time resolution and at 2 GHz using the Nan\c{c}ay radio telescope with an instrument doing coherent dedispersion and able to record giant pulses data. We have studied the delay between the radio and optical pulse using simultaneously obtained data therefore reducing possible uncertainties present in previous observations. We determined the arrival times of the (mean) optical and radio pulse and compared them using the tempo2 software package. We present the most accurate value for the optical-radio lag of 255 $\pm$ 21 $\mu$s and suggest the likelihood of a spectral dependence to the excess optical emission asociated with giant radio pulses.Comment: 8 pages; accepted for publication in Astronomy and Astrophysic

Mapping the spatial distribution of the Japanese encephalitis vector, Culex tritaeniorhynchus Giles, 1901 (Diptera: Culicidae) within areas of Japanese encephalitis risk

Background Japanese encephalitis (JE) is one of the most significant aetiological agents of viral encephalitis in Asia. This medically important arbovirus is primarily spread from vertebrate hosts to humans by the mosquito vector Culex tritaeniorhynchus. Knowledge of the contemporary distribution of this vector species is lacking, and efforts to define areas of disease risk greatly depend on a thorough understanding of the variation in this mosquito’s geographical distribution. Results We assembled a contemporary database of Cx. tritaeniorhynchus presence records within Japanese encephalitis risk areas from formal literature and other relevant resources, resulting in 1,045 geo-referenced, spatially and temporally unique presence records spanning from 1928 to 2014 (71.9% of records obtained between 2001 and 2014). These presence data were combined with a background dataset capturing sample bias in our presence dataset, along with environmental and socio-economic covariates, to inform a boosted regression tree model predicting environmental suitability for Cx. tritaeniorhynchus at each 5 × 5 km gridded cell within areas of JE risk. The resulting fine-scale map highlights areas of high environmental suitability for this species across India, Nepal and China that coincide with areas of high JE incidence, emphasising the role of this vector in disease transmission and the utility of the map generated. Conclusions Our map contributes towards efforts determining the spatial heterogeneity in Cx. tritaeniorhynchus distribution within the limits of JE transmission. Specifically, this map can be used to inform vector control programs and can be used to identify key areas where the prevention of Cx. tritaeniorhynchus establishment should be a priority

Automated Synthesis of Tableau Calculi

This paper presents a method for synthesising sound and complete tableau calculi. Given a specification of the formal semantics of a logic, the method generates a set of tableau inference rules that can then be used to reason within the logic. The method guarantees that the generated rules form a calculus which is sound and constructively complete. If the logic can be shown to admit finite filtration with respect to a well-defined first-order semantics then adding a general blocking mechanism provides a terminating tableau calculus. The process of generating tableau rules can be completely automated and produces, together with the blocking mechanism, an automated procedure for generating tableau decision procedures. For illustration we show the workability of the approach for a description logic with transitive roles and propositional intuitionistic logic.Comment: 32 page

The Mineralogical Record of Oxygen Fugacity Variation and Alteration in Northwest Africa 8159: Evidence for Interaction Between a Mantle Derived Martian Basalt and a Crustal Component(s)

A prominent geochemical feature of basaltic magmatism on Mars is the large range in initial Sr isotopic ratios (approx. 0.702 - 0.724) and initial epsilon-Nd values (approx. -10 to greater than +50). Within this range, the shergottites fall into three discreet subgroups. These subgroups have distinct bulk rock REE patterns, mineral chemistries (i.e. phosphate REE patterns, Ni, Co, V in olivine), oxygen fugacity of crystallization, and stable isotopes, such as O. In contrast, nakhlites and chassignites have depleted epsilon-Nd values (greater than or equal to +15), have REE patterns that are light REE enriched, and appear to have crystallized near the FMQ buffer. The characteristics of these various martian basalts have been linked to different reservoirs in the martian crust and mantle, and their interactions during the petrogenesis of these magmas. These observations pose interesting interpretive challenges to our understanding of the conditions of the martian mantle (e.g. oxygen fugacity) and the interaction of mantle derived magmas with the martian crust and surface. Martian meteorite NWA 8159 is a unique fine-grained augite basalt derived from a highly depleted mantle source as reflected in its initial epsilon-Nd value, contains a pronounced light REE depleted pattern, and crystallized presumably under very oxidizing conditions. Although considerably older than both shergottites and nahklites, it has been petrogenetically linked to both styles of martian magmatism. These unique characteristics of NWA 8159 may provide an additional perspective for deciphering the petrogenesis of martian basalts and the nature of the crust of Mars