Josephson Effect in Pb/I/NbSe2 Scanning Tunneling Microscope Junctions

We have developed a method for the reproducible fabrication of superconducting scanning tunneling microscope (STM) tips. We use these tips to form superconductor/insulator/superconductor tunnel junctions with the STM tip as one of the electrodes. We show that such junctions exhibit fluctuation dominated Josephson effects, and describe how the Josephson product IcRn can be inferred from the junctions' tunneling characteristics in this regime. This is first demonstrated for tunneling into Pb films, and then applied in studies of single crystals of NbSe2. We find that in NbSe2, IcRn is lower than expected, which could be attributed to the interplay between superconductivity and the coexisting charge density wave in this material.Comment: 3 pages, 2 figures. Presented at the New3SC-4 meeting, San Diego, Jan. 16-21 200

Demographics and prevalent risk factors of chronic subdural haematoma: results of a large single-center cohort study

Chronic subdural haematoma (CSDH) is a typical disease in elderly patients and encountered frequently in neurosurgical practice. With an increasing number of elderly people in the general population, there is a need to investigate risk factors (age, falls, anticoagulant or antithrombotic therapy) which could be pertinent to the development of this disease. We reviewed 354 patients undergoing surgery for CSDH over a period of 7 years (1996-2002), the occurrence being equally distributed over these years. CSDH occurred more often in elderly (≥65 years) than in younger people (69 vs 31%), and in men than in women (64 vs 36%). Falls were reported in 77% of patients. There was a trend towards a higher risk of falls in the elderly. Antithrombotic or anticoagulant therapy was present in 41% of patients, 32% of them having had falls. Overall postoperative mortality was 0% and overall recurrence rate 13.6%. CSDH in the elderly population, especially in men, is frequently associated with falls and anticoagulation or antithrombotic therapy. The indication for these medications, especially in elderly patients at risk for falls, should be carefully evaluated and controlle

Thermo-mechanical behaviour of a compacted swelling clay

Compacted unsaturated swelling clay is often considered as a possible buffer material for deep nuclear waste disposal. An isotropic cell permitting simultaneous control of suction, temperature and pressure was used to study the thermo-mechanical behaviour of this clay. Tests were performed at total suctions ranging from 9 to 110 MPa, temperature from 25 to 80 degrees C, isotropic pressure from 0.1 to 60 MPa. It was observed that heating at constant suction and pressure induces either swelling or contraction. The results from compression tests at constant suction and temperature evidenced that at lower suction, the yield pressure was lower, the elastic compressibility parameter and the plastic compressibility parameter were higher. On the other hand, at a similar suction, the yield pressure was slightly influenced by the temperature; and the compressibility parameters were insensitive to temperature changes. The thermal hardening phenomenon was equally evidenced by following a thermo-mechanical path of loading-heating-cooling-reloading

Vortices on Higher Genus Surfaces

We consider the topological interactions of vortices on general surfaces. If the genus of the surface is greater than zero, the handles can carry magnetic flux. The classical state of the vortices and the handles can be described by a mapping from the fundamental group to the unbroken gauge group. The allowed configurations must satisfy a relation induced by the fundamental group. Upon quantization, the handles can carry ``Cheshire charge.'' The motion of the vortices can be described by the braid group of the surface. How the motion of the vortices affects the state is analyzed in detail.Comment: 28 pages with 10 figures; uses phyzzx and psfig; Caltech preprint CALT-68-187

Quantum Energies of Strings in a 2+1 Dimensional Gauge Theory

We study classically unstable string type configurations and compute the renormalized vacuum polarization energies that arise from fermion fluctuations in a 2+1 dimensional analog of the standard model. We then search for a minimum of the total energy (classical plus vacuum polarization energies) by varying the profile functions that characterize the string. We find that typical string configurations bind numerous fermions and that populating these levels is beneficial to further decrease the total energy. Ultimately our goal is to explore the stabilization of string type configurations in the standard model through quantum effects. We compute the vacuum polarization energy within the phase shift formalism which identifies terms in the Born series for scattering data and Feynman diagrams. This approach allows us to implement standard renormalization conditions of perturbation theory and thus yields the unambiguous result for this non--perturbative contribution to the total energy.Comment: 26 pages, 20 eps-files combined to 8 figures, minor typos corrected. Version to be published in Nucl. Phys.

Validation of the French Versions of the Flourish Index and the Secure Flourish Index

Individual well-being is generally thought of from the perspective of the risk factors which might compromise it. Assuming that positive dimensions of well-being are also worth considering, VanderWeele and Wȩziak-Białowolska et al. developed and tested the Flourish Index (FI) and the Secure Flourish Index (SFI). These 10- and 12-item questionnaires, respectively, measure 5 and 6 dimensions of human flourishing. This article presents the translation of these indexes into French (as FI–F and SFI–F) and the assessment of their psychometric properties on a sample of 2,376 French-speaking respondents. The validity and reliability indicators used by Wȩziak-Białowolska et al. were calculated for our French indexes and found to be very close to theirs. Item groupings were confirmed using correlation and factor analyses. The hierarchical structure of both French indexes matched the English indexes’ second-order and bi-factor model analyses. Reliability and construct validity were good. The brief time required to complete the FI–F or SFI–F and their excellent psychometric properties make them very promising tools for research on the general well-being of Francophone populations

The promoter from SlREO, a highly-expressed, root-specific Solanum lycopersicum gene, directs expression to cortex of mature roots

Root-specific promoters are valuable tools for targeting transgene expression, but many of those already described have limitations to their general applicability. We present the expression characteristics of SlREO, a novel gene isolated from tomato (Solanum lycopersicum L.). This gene was highly expressed in roots but had a very low level of expression in aerial plant organs. A 2.4-kb region representing the SlREO promoter sequence was cloned upstream of the uidA GUS reporter gene and shown to direct expression in the root cortex. In mature, glasshouse-grown plants this strict root specificity was maintained. Furthermore, promoter activity was unaffected by dehydration or wounding stress but was somewhat suppressed by exposure to NaCl, salicylic acid and jasmonic acid. The predicted protein sequence of SlREO contains a domain found in enzymes of the 2-oxoglutarate and Fe(II)-dependent dioxygenase superfamily. The novel SlREO promoter has properties ideal for applications requiring strong and specific gene expression in the bulk of tomato root tissue growing in soil, and is also likely to be useful in other Solanaceous crop

Use of surrogate endpoints in healthcare policy : proposal for consistent adoption of a validation framework

We propose a three step framework for the evaluation of surrogate endpoints for health policy decisions on health technologies

Classical confinement of test particles in higher-dimensional models: stability criteria and a new energy condition

We review the circumstances under which test particles can be localized around a spacetime section \Sigma_0 smoothly contained within a codimension-1 embedding space M. If such a confinement is possible, \Sigma_0 is said to be totally geodesic. Using three different methods, we derive a stability condition for trapped test particles in terms of intrinsic geometrical quantities on \Sigma_0 and M; namely, confined paths are stable against perturbations if the gravitational stress-energy density on M is larger than that on \Sigma_0, as measured by an observed travelling along the unperturbed trajectory. We confirm our general result explicitly in two different cases: the warped-product metric ansatz for (n+1)-dimensional Einstein spaces, and a known solution of the 5-dimensional vacuum field equation embedding certain 4-dimensional cosmologies. We conclude by defining a confinement energy condition that can be used to classify geometries incorporating totally geodesic submanifolds, such as those found in thick braneworld and other 5-dimensional scenarios.Comment: 9 pages, REVTeX4, in press in Phys. Rev.