Controlled crack growth specimen for brittle systems

A pure Mode 1 fracture specimen and test procedure has been developed which provides extended, stable, through-thickness crack growth in ceramics and other brittle, nonmetallic materials. Fixed displacement loading, applied at the crack mouth, promotes stable crack extension by reducing the stored elastic strain energy. Extremely fine control of applied displacements is achieved by utilizing the Poisson's expansion of a compressively loaded cylindrical pin. Stable cracks were successfully grown in soda-lime glass and monolithic Al2O3 for lengths in excess of 20 mm without uncontrollable catastrophic failure

Rehabilitation planning for small tanks in cascades: a methodology based on rapid assessment

Irrigation systems / Rehabilitation / Tank irrigation / Small-scale systems / Reservoirs / Conflict / Farmer participation / River Basin development / Water resources development / Arid zones / Sri Lanka

Numerical calibration of the stable poisson loaded specimen

An analytical calibration of the Stable Poisson Loaded (SPL) specimen is presented. The specimen configuration is similar to the ASTM E-561 compact-tension specimen with displacement controlled wedge loading used for R-Curve determination. The crack mouth opening displacements (CMOD's) are produced by the diametral expansion of an axially compressed cylindrical pin located in the wake of a machined notch. Due to the unusual loading configuration, a three-dimensional finite element analysis was performed with gap elements simulating the contact between the pin and specimen. In this report, stress intensity factors, CMOD's, and crack displacement profiles are reported for different crack lengths and different contacting conditions. It was concluded that the computed stress intensity factor decreases sharply with increasing crack length, thus making the SPL specimen configuration attractive for fracture testing of brittle, high modulus materials

Clinical and cost-effectiveness of capecitabine and tegafur with uracil for the treatment of metastatic colorectal cancer: systematic review and economic evaluation

Objectives: To evaluate the clinical and costeffectiveness of capecitabine and tegafur with uracil (UFT/LV) as first-line treatments for patients with metastatic colorectal cancer, as compared with 5- fluorouracil/folinic acid (5-FU/FA) regimens. Data sources: Electronic databases, reference lists of relevant articles and sponsor submissions were also consulted. Review methods: Systematic searches, selection against criteria and quality assessment were performed to obtain data from relevant studies. Costs were estimated through resource-use data taken from the published trials and the unpublished sponsor submissions. Unit costs were taken from published sources, where available. An economic evaluation was undertaken to compare the cost-effectiveness of capecitabine and UFT/LV with three intravenous 5- FU/LV regimens widely used in the UK: the Mayo, the modified de Gramont regimen and the inpatient de Gramont regimens. Results: The evidence suggests that treatment with capecitabine improves overall response rates and has an improved adverse effect profile in comparison with 5-FU/LV treatment with the Mayo regimen, with the exception of hand–foot syndrome. Time to disease progression or death after treatment with UFT/LV in one study appears to be shorter than after treatment with 5-FU/LV with the Mayo regimen, although it also had an improved adverse effect profile. Neither capecitabine nor UFT/LV appeared to improve healthrelated quality of life. Little information on patient preference was available for UFT/LV, but there was indicated a strong preference for this over 5-FU/LV. The total cost of capecitabine and UFT/LV treatments were estimated at £2111 and £3375, respectively, compared with the total treatment cost for the Mayo regimen of £3579. Cost estimates were also presented for the modified de Gramont and inpatient de Gramont regimens. These were £3684 and £6155, respectively. No survival advantage was shown in the RCTs of the oral drugs against the Mayo regimen. Cost savings of capecitabine and UFT/LV over the Mayo regimen were estimated to be £1461 and £209, respectively. Drug acquisition costs were higher for the oral therapies than for the Mayo regimen, but were offset by lower administration costs. Adverse event treatment costs were similar across the three regimens. It was inferred that there was no survival difference between the oral drugs and the de Gramont regimens. Cost savings of capecitabine and UFT/LV over the modified de Gramont regimen were estimated to be £1353 and £101, respectively, and over the inpatient de Gramont regimen were estimated to be £4123 and £2870, respectively. Conclusions: The results show that there are cost savings associated with the use of oral therapies. No survival difference has been proven between the oral drugs and the Mayo regimen. In addition, no evidence of a survival difference between the Mayo regimen and the de Gramont regimens has been identified. However, improved progression-free survival and an improved adverse event profile have been shown for the de Gramont regimen over the Mayo regimen. Further research is recommended into the following areas: quality of life data should be included in trials of colorectal cancer treatments; the place of effective oral treatments in the treatment of colorectal cancer, the safety mechanisms needed to ensure compliance and the monitoring of adverse effects; the optimum duration of treatment; the measurement of patient preference; and a phase III comparative trial of capecitabine and UFT/LV versus modified de Gramont treatment to determine whether there was any survival advantage and to collate the necessary economic data

UniquID: A Quest to Reconcile Identity Access Management and the Internet of Things

The Internet of Things (IoT) has caused a revolutionary paradigm shift in computer networking. After decades of human-centered routines, where devices were merely tools that enabled human beings to authenticate themselves and perform activities, we are now dealing with a device-centered paradigm: the devices themselves are actors, not just tools for people. Conventional identity access management (IAM) frameworks were not designed to handle the challenges of IoT. Trying to use traditional IAM systems to reconcile heterogeneous devices and complex federations of online services (e.g., IoT sensors and cloud computing solutions) adds a cumbersome architectural layer that can become hard to maintain and act as a single point of failure. In this paper, we propose UniquID, a blockchain-based solution that overcomes the need for centralized IAM architectures while providing scalability and robustness. We also present the experimental results of a proof-of-concept UniquID enrolment network, and we discuss two different use-cases that show the considerable value of a blockchain-based IAM.Comment: 15 pages, 10 figure

Capture and isolation of highly-charged ions in a unitary Penning trap

We recently used a compact Penning trap to capture and isolate highly-charged ions extracted from an electron beam ion trap (EBIT) at the National Institute of Standards and Technology (NIST). Isolated charge states of highly-stripped argon and neon ions with total charge $Q \geq 10$, extracted at energies of up to $4\times 10^3\,Q$ eV, are captured in a trap with well depths of $\,\approx (4\, {\rm to}\, 12)\,Q$ eV. Here we discuss in detail the process to optimize velocity-tuning, capture, and storage of highly-charged ions in a unitary Penning trap designed to provide easy radial access for atomic or laser beams in charge exchange or spectroscopic experiments, such as those of interest for proposed studies of one-electron ions in Rydberg states or optical transitions of metastable states in multiply-charged ions. Under near-optimal conditions, ions captured and isolated in such rare-earth Penning traps can be characterized by an initial energy distribution that is $\approx$ 60 times narrower than typically found in an EBIT. This reduction in thermal energy is obtained passively, without the application of any active cooling scheme in the ion-capture trap.Comment: 10 pages, 11 figures, Accepted in Phys. Rev.

Modification of silicon carbide fibers for use in SiC/Ti composites

The degradation of silicon carbide fibers during exposure to conditions typical of composite fabrication was investigated. The tensile strength of pristine fibers and fibers sputtered with thin metal coatings were determined before and after treatment at 870 C for one hour in vacuum. Each fiber strength distribution was related by an analytical procedure to a projected composite ultimate tensile strength (PC UTS). The results indicate that a thin aluminum diffusion barrier can yield a 150 percent increase in PC UTS over the baseline SiC/Ti system

Kronos & Krios: Evidence for accretion of a massive, rocky planetary system in a comoving pair of solar-type stars

We report and discuss the discovery of a comoving pair of bright solar-type stars, HD 240430 and HD 240429, with a significant difference in their chemical abundances. The two stars have an estimated 3D separation of $\approx 0.6$ pc ($\approx 0.01$ pc projected) at a distance of $r\approx 100$ pc with nearly identical three-dimensional velocities, as inferred from Gaia TGAS parallaxes and proper motions, and high-precision radial velocity measurements. Stellar parameters determined from high-resolution Keck HIRES spectra indicate that both stars are $\sim 4$ Gyr old. The more metal-rich of the two, HD 240430, shows an enhancement of refractory ($T_C>1200$ K) elements by $\approx 0.2$ dex and a marginal enhancement of (moderately) volatile elements ($T_C<1200$ K, C, N, O, Na, and Mn). This is the largest metallicity difference found in a wide binary pair yet. Additionally, HD 240430 shows an anomalously high surface lithium abundance ($A(\mathrm{Li})=2.75$), higher than its companion by $0.5$ dex. The proximity in phase-space and ages between the two stars suggests that they formed together with the same composition, at odds with the observed differences in metallicity and abundance patterns. We therefore suggest that the star HD~240430, "Kronos", accreted 15 $M_\oplus$ of rocky material after birth, selectively enhancing the refractory elements as well as lithium in its surface and convective envelope.Comment: Figure 9 is the main figure, submitte

Fe I Oscillator Strengths for the Gaia-ESO Survey

The Gaia-ESO Public Spectroscopic Survey (GES) is conducting a large-scale study of multi-element chemical abundances of some 100 000 stars in the Milky Way with the ultimate aim of quantifying the formation history and evolution of young, mature and ancient Galactic populations. However, in preparing for the analysis of GES spectra, it has been noted that atomic oscillator strengths of important Fe I lines required to correctly model stellar line intensities are missing from the atomic database. Here, we present new experimental oscillator strengths derived from branching fractions and level lifetimes, for 142 transitions of Fe I between 3526 {\AA} and 10864 {\AA}, of which at least 38 are urgently needed by GES. We also assess the impact of these new data on solar spectral synthesis and demonstrate that for 36 lines that appear unblended in the Sun, Fe abundance measurements yield a small line-by-line scatter (0.08 dex) with a mean abundance of 7.44 dex in good agreement with recent publications.Comment: Accepted for publication in Mon. Not. R. Astron. So

Reflection high-energy electron diffraction experimental analysis of polycrystalline MgO films with grain size and orientation distributions

Analysis of biaxial texture of MgO films grown by ion-beam-assisted deposition (IBAD) has been performed using a quantitative reflection high-energy electron diffraction (RHEED) based method. MgO biaxial texture is determined by analysis of diffraction spot shapes from single RHEED images, and by measuring the width of RHEED in-plane rocking curves for MgO films grown on amorphous Si3N4 by IBAD using 750 eV Ar+ ions, at 45° incidence angle, and MgO e-beam evaporation. RHEED-based biaxial texture measurement accuracy is verified by comparison with in-plane and out-of-plane orientation distribution measurements made using transmission electron microscopy and x-ray rocking curves. In situ RHEED measurements also enable the analysis of the evolution of the biaxial texture which narrows with increasing film thickness. RHEED-based measurements of IBAD MgO biaxial texture show that the minimum in-plane orientation distribution depends on the out-of-plane orientation distribution, and indicates that the minimum obtainable in-plane orientation on distribution is 2°