Electrical resistivity measurements of lattice defects in hexagonal close packed metals

Lattice defects produced in zinc and cadmium by plastic deformation at 78 K have been investigated by means of electrical resistivity measurements at 78 K. Single crystals and polycrystalline samples of both metals have been used. The annealable increase in the resistivity of single crystals with deformation is generally less than 0.5% for deformations of up to 5% in zinc and 10% in cadmium. This is too small for annealing stages to be resolved satisfactorily, particularly since they are obscured by irregular changes in resistance during annealing, attributed to anisotropic thermal expansion of neighbouring sub-grains. Polycrystalline zinc is too brittle to allow significant deformation at low temperature, but a measurable resistivity increase has been produced in polycrystalline cadmium. The increase is proportional to strain, with a coefficient (12.5 ± 0.7) nQm per unit strain, half due to dislocations and half to point defects. This value is consistent with the point defect production mechanism being nonconservative movement of dislocation jogs, producing a defect concentration of 0.1% per unit strain, the resistivity of defects being 60 nΩm per 1% atomic concentration. Isochronal and sequential isothermal annealing was performed, and the activation energy was determined by an improved version of the change-of-slope method which eliminates the necessity for subjective curve-fitting operations. The annealing spectrum was divided into three stages: stage III, at 80 to 130 K, activation energy 0.16 ± 0.03 eV; stage IV, at 130 to 180 K, activation energy increasing from 0.2 eV to -0.4 eV; and stage V, 180 to 220 K, 0.7 ± 0.1 eV. There was no unique order of kinetics at any stage, and it appears that a number of overlapping processes took place. Stage III is attributed to the annealing of interstitials and stage IV to vacancies, but both these defects probably moved in groups of two or more and interacted with impurities. Stage V is attributed to dislocation rearrangement

Scientific conferences, socialization, and the Covid-19 pandemic:a conceptual and empirical enquiry

Since the 1970s social analysts have seen communication between scientists not solely as information exchange (the algorithmical model), but as a process of socialization into overlapping and mutually embedded scientific domains (the enculturational model). Under the algorithmical model, the impact of the Covid-19 shutdown on travel would be easily remedied by replacing face-to-face communication with online platforms. Conferences and similar gatherings are costly, elitist, and environmentally damaging, but under the enculturational model abandoning them could be disastrous for science, which depends on the development of cross-national trust and mutual agreements through face-to-face interaction and, in turn, disastrous for science’s role in democracy. We explore the problem theoretically and empirically, arguing against recent proposals from some scientists for the wholesale and permanent replacement of conferences with remote communication

Evaluating Communication Tools and Increasing Fruit and Vegetable Consumption in Vermont Head Start Classrooms

Introduction: We designed a program for four Head Start classrooms that aimed to: 1) Provide classrooms a tool that would facilitate communication with families about nutrition, 2) Educate families about the MyMeal tool, and 3) Increase fruit and vegetable consumption by providing families with fresh fruits and vegetables Fruit and vegetables are important components of a healthy diet, and sufficient consumption helps reduce the risk of developing cardiovascular disease, cancer, diabetes and obesity. Eating behaviors during childhood are highly parentally influenced and function as the foundation for future eating patterns. Studies have shown that the extent to which fruits and vegetables are present and accessible in the home correlates with the amount of fruit and vegetables eaten by children.https://scholarworks.uvm.edu/comphp_gallery/1210/thumbnail.jp

GPS-Geodetic Deformation Monitoring of the South-west Seismic Zone of Western Australia: Review, Description of Methodology and Results from Epoch-one

The south-west seismic zone (SWSZ) is a northwest-southeast trending belt of intraplate earthquake activity that occurs in the south-western corner of Western Australia, and is one of the most seismically active areas in Australia. Since the SWSZ lies as close as ~150 km from the ~1.4 million population of the Perth region, it poses a distinct seismic hazard. Earthquake activity recorded by Geoscience Australia over the past three decades suggests that the SWSZ could be deforming by 0.5-5 mmy-1. However, little is currently known about the magnitude and orientation of this deformation, and whether there is any associated surface expression. Previous geodetic studies of the SWSZ that used both terrestrial and Global Positioning System (GPS) techniques are inconclusive, due mainly to the imprecision of the technologies used in relation to the likely small amount of any surface deformation. Therefore, a new 48-point GPS-geodetic monitoring network has been established across the SWSZ to attempt to detect surface deformation, for which epoch-one episodic GPS-geodetic measurements were made in May 2002. This paper briefly reviews previous attempts to geodetically measure surface deformation across the SWSZ, summarises the scientific rationale for the new project, describes the network design and observations used, results of the May 2002 campaign (epoch-one) and discusses future work, including issues pertaining to the likely amount of surface deformation that can be detected

Capturing themed evidence, a hybrid approach

The task of identifying pieces of evidence in texts is of fundamental importance in supporting qualitative studies in various domains, especially in the humanities. In this paper, we coin the expression themed evidence, to refer to (direct or indirect) traces of a fact or situation relevant to a theme of interest and study the problem of identifying them in texts. We devise a generic framework aimed at capturing themed evidence in texts based on a hybrid approach, combining statistical natural language processing, background knowledge, and Semantic Web technologies. The effectiveness of the method is demonstrated in a case study of a digital humanities database aimed at collecting and curating a repository of evidence of experiences of listening to music. Extensive experiments demonstrate that our hybrid approach outperforms alternative solutions. We also evidence its generality by testing it on a different use case in the digital humanities

The self-force on a static scalar test-charge outside a Schwarzschild black hole

The finite part of the self-force on a static scalar test-charge outside a Schwarzschild black hole is zero. By direct construction of Hadamard's elementary solution, we obtain a closed-form expression for the minimally coupled scalar field produced by a test-charge held fixed in Schwarzschild spacetime. Using the closed-form expression, we compute the necessary external force required to hold the charge stationary. Although the energy associated with the scalar field contributes to the renormalized mass of the particle (and thereby its weight), we find there is no additional self-force acting on the charge. This result is unlike the analogous electrostatic result, where, after a similar mass renormalization, there remains a finite repulsive self-force acting on a static electric test-charge outside a Schwarzschild black hole. We confirm our force calculation using Carter's mass-variation theorem for black holes. The primary motivation for this calculation is to develop techniques and formalism for computing all forces - dissipative and non-dissipative - acting on charges and masses moving in a black-hole spacetime. In the Appendix we recap the derivation of the closed-form electrostatic potential. We also show how the closed-form expressions for the fields are related to the infinite series solutions.Comment: RevTeX, To Appear in Phys. Rev.

Radiative multipole moments of integer-spin fields in curved spacetime

Radiative multipole moments of scalar, electromagnetic, and linearized gravitational fields in Schwarzschild spacetime are computed to third order in v in a weak-field, slow-motion approximation, where v is a characteristic velocity associated with the motion of the source. To zeroth order in v, a radiative moment of order l is given by the corresponding source moment differentiated l times with respect to retarded time. At second order in v, additional terms appear inside the spatial integrals. These are near-zone corrections which depend on the detailed behavior of the source. At third order in v, the correction terms occur outside the spatial integrals, so that they do not depend on the detailed behavior of the source. These are wave-propagation corrections which are heuristically understood as arising from the scattering of the radiation by the spacetime curvature surrounding the source. Our calculations show that the wave-propagation corrections take a universal form which is independent of multipole order and field type. We also show that in general relativity, temporal and spatial curvatures contribute equally to the wave-propagation corrections.Comment: 34 pages, ReVTe

HILT : High-Level Thesaurus Project M2M Feasibility Study : [Final Report]

The project was asked to investigate the feasibility of developing SOAP-based interfaces between JISC IE services and Wordmap APIs and non-Wordmap versions of the HILT pilot demonstrator created under HILT Phase II and to determine the scope and cost of the provision of an actual demonstrator based on each of these approaches. In doing so it was to take into account the possibility of a future Zthes1-based solution using Z39.50 or OAI-PMH and syntax and data-exchange protocol implications of eScience and semantic-web developments. It was agreed that the primary concerns of the study should be an assessment of the feasibility, scope, and cost of a follow-up M2M pilot that considered the best options in respect of: o Query protocols (SOAP, Z39.50, SRW, OAI) and associated data profiles (e.g. Zthes for Z39.50 and for SRW); o Standards for structuring thesauri and thesauri-type information (e.g. the Zthes XML DTD and SRW version of it and SKOS-Core2); The study was carried out within the allotted timescale, with this Final Report submitted to JISC on 31st March 2005 as scheduled. The detailed proposal for a follow-up project is currently under discussion and will be finalised – as agreed with JISC – by mid-April. It was concluded that an M2M pilot was feasible. A proposal for a follow-up M2M pilot project has been scoped, and is currently being costed

Mass segregation in young compact star clusters in the Large Magellanic Cloud: I. Data and Luminosity Functions

We have undertaken a detailed analysis of HST/WFPC2 and STIS imaging observations, and of supplementary wide-field ground-based observations obtained with the NTT of two young ~10-25 Myr) compact star clusters in the LMC, NGC 1805 and NGC 1818. The ultimate goal of our work is to improve our understanding of the degree of primordial mass segregation in star clusters. This is crucial for the interpretation of observational luminosity functions (LFs) in terms of the initial mass function (IMF), and for constraining the universality of the IMF. We present evidence for strong luminosity segregation in both clusters. The LF slopes steepen with cluster radius; in both NGC 1805 and NGC 1818 the LF slopes reach a stable level well beyond the clusters' core or half-light radii. In addition, the brightest cluster stars are strongly concentrated within the inner ~4 R_hl. The global cluster LF, although strongly nonlinear, is fairly well approximated by the core or half-light LF; the (annular) LFs at these radii are dominated by the segregated high-luminosity stars, however. We present tentative evidence for the presence of an excess number of bright stars surrounding NGC 1818, for which we argue that they are most likely massive stars that have been collisionally ejected from the cluster core. We therefore suggest that the cores of massive young stars clusters undergo significant dynamical evolution, even on time-scales as short as ~25 Myr.Comment: 19 pages, incl. 10 embedded postscript figures, MNRAS, resubmitted (referee's comments included

Bending the curve of global freshwater biodiversity loss: an emergency recovery plan

Despite their limited spatial extent, freshwater ecosystems host remarkable biodiversity, including one-third of all vertebrate species. This biodiversity is declining dramatically: Globally, wetlands are vanishing three times faster than forests, and freshwater vertebrate populations have fallen more than twice as steeply as terrestrial or marine populations. Threats to freshwater biodiversity are well documented but coordinated action to reverse the decline is lacking. We present an Emergency Recovery Plan to bend the curve of freshwater biodiversity loss. Priority actions include accelerating implementation of environmental flows; improving water quality; protecting and restoring critical habitats; managing the exploitation of freshwater ecosystem resources, especially species and riverine aggregates; preventing and controlling nonnative species invasions; and safeguarding and restoring river connectivity. We recommend adjustments to targets and indicators for the Convention on Biological Diversity and the Sustainable Development Goals and roles for national and international state and nonstate actors