Development of uniform and predictable battery materials for nickel cadmium aerospace cells Quarterly report, 8 Aug. - 7 Nov. 1968

Sintering of carbonyl nickel powders for nickel cadmium batteries fabricatio

Cost-effectiveness of ranibizumab for neovascular age-related macular degeneration

<p>Abstract</p> <p>Background</p> <p>Intravitreal ranibizumab prevents vision loss and improves visual acuity in patients with neovascular age-related macular degeneration, but it is expensive, and efficacy beyond 2 years is uncertain.</p> <p>Methods</p> <p>We assessed the cost-effectiveness of ranibizumab compared with no ranibizumab over 10 years, using randomized trial efficacy data for the first 2 years, post-trial efficacy assumptions, and ranibizumab acquisition costs ranging from the wholesale price ($1,950 per dose) to the price of bevazicumab ($50), a similar molecule which may be equally efficacious. We used a computer simulation model to estimate the probability of blindness, the number of quality-adjusted life-years (QALYs), direct costs (in 2004 U.S. dollars), and cost-effectiveness ratios for a 67-year old woman. Costs and QALYs were discounted at 3% per year.</p> <p>Results</p> <p>The probability of blindness over 10 years was reduced from 56% to 34% if ranibizumab was efficacious for only 2 years, 27% if efficacy was maintained for a further 2 years only (base-case scenario), and 17% if visual acuity at 4 years was then sustained. It was cost-saving under all price assumptions, when caregiver costs were included. When caregiver costs were excluded, the cost per QALY for the base-case ranged from $5,600, assuming the bevazicumab price, to$91,900 assuming the wholesale ranibizumab price. The cost per QALY was < $50,000 when the cost of ranibizumab was less than$1000.</p> <p>Conclusion</p> <p>From a societal perspective, ranibizumab was cost-saving. From a health care funder's perspective, ranibizumab was an efficient treatment when it cost less than $1000 per dose.</p

Cost-effectiveness of smoking cessation to prevent age-related macular degeneration

<p>Abstract</p> <p>Background</p> <p>Tobacco smoking is a risk factor for age-related macular degeneration, but studies of ex-smokers suggest quitting can reduce the risk.</p> <p>Methods</p> <p>We fitted a function predicting the decline in risk of macular degeneration after quitting to data from 7 studies involving 1,488 patients. We assessed the cost-effectiveness of smoking cessation in terms of its impact on macular degeneration-related outcomes for 1,000 randomly selected U.S. smokers. We used a computer simulation model to predict the incidence of macular degeneration and blindness, the number of quality-adjusted life-years (QALYs), and direct costs (in 2004 U.S. dollars) until age 85 years. Cost-effectiveness ratios were based on the cost of the Massachusetts Tobacco Control Program. Costs and QALYs were discounted at 3% per year.</p> <p>Results</p> <p>If 1,000 smokers quit, our model predicted 48 fewer cases of macular degeneration, 12 fewer cases of blindness, and a gain of 1,600 QALYs. Macular degeneration-related costs would decrease by $2.5 million if the costs of caregivers for people with vision loss were included, or by$1.1 million if caregiver costs were excluded. At a cost of $1,400 per quitter, smoking cessation was cost-saving when caregiver costs were included, and cost about$200 per QALY gained when caregiver costs were excluded. Sensitivity analyses had a negligible impact. The cost per quitter would have to exceed $77,000 for the cost per QALY for smoking cessation to reach$50,000, a threshold above which interventions are sometimes viewed as not cost-effective.</p> <p>Conclusion</p> <p>Smoking cessation is unequivocally cost-effective in terms of its impact on age-related macular degeneration outcomes alone.</p

X-Ray Light Curves of Gamma-ray Bursts Detected with the All-Sky Monitor on RXTE

We present X-ray light curves (1.5-12 keV) for fifteen gamma-ray bursts (GRBs) detected by the All-Sky Monitor on the Rossi X-ray Timing Explorer. We compare these soft X-ray light curves with count rate histories obtained by the high-energy (>12 keV) experiments BATSE, Konus-Wind, the BeppoSAX Gamma-Ray Burst Monitor, and the burst monitor on Ulysses. We discuss these light curves within the context of a simple relativistic fireball and synchrotron shock paradigm, and we address the possibility of having observed the transition between a GRB and its afterglow. The light curves show diverse morphologies, with striking differences between energy bands. In several bursts, intervals of significant emission are evident in the ASM energy range with little or no corresponding emission apparent in the high-energy light curves. For example, the final peak of GRB 970815 as recorded by the ASM is only detected in the softest BATSE energy bands. We also study the duration of bursts as a function of energy. Simple, singly-peaked bursts seem consistent with the E^{-0.5} power law expected from an origin in synchrotron radiation, but durations of bursts that exhibit complex temporal structure are not consistent with this prediction. Bursts such as GRB 970828 that show many short spikes of emission at high energies last significantly longer at low energies than the synchrotron cooling law would predict.Comment: 15 pages with 20 figures and 2 tables. In emulateapj format. Accepted by ApJ

A high-resolution gamma-ray and hard X-ray spectrometer for solar flare observations in Max 1991

A long duration balloon flight instrument for Max 1991 designed to study the acceleration of greater than 10 MeV ions and greater than 15 keV electrons in solar flares through high resolution spectroscopy of the gamma ray lines and hard X-ray and gamma ray continuum is described. The instrument, HIREGS, consists of an array of high-purity, n-type coaxial germanium detectors (HPGe) cooled to less than 90 K and surrounded by a bismuth germanate (BGO) anticoincidence shield. It will cover the energy range 15 keV to 20 MeV with keV spectral resolution, sufficient for accurate measurement of all parameters of the expected gamma ray lines with the exception of the neutron capture deuterium line. Electrical segmentation of the HPGe detector into a thin front segment and a thick rear segment, together with pulse-shape discrimination, provides optimal dynamic range and signal-to-background characteristics for flare measurements. Neutrons and gamma rays up to approximately 0.1 to 1 GeV can be detected and identified with the combination of the HPGe detectors and rear BGO shield. The HIREGS is planned for long duration balloon flights (LDBF) for solar flare studies during Max 1991. The two exploratory LDBFs carried out at mid-latitudes in 1987 to 1988 are described, and the LDBFs in Antarctica, which could in principle provide 24 hour/day solar coverage and very long flight durations (20 to 30 days) because of minimal ballast requirements are discussed

Large Torque Variations in Two Soft Gamma Repeaters

We have monitored the pulse frequencies of the two soft gamma repeaters SGR 1806-20 and SGR 1900+14 through the beginning of year 2001 using primarily Rossi X-ray Timing Explorer Proportional Counter Array observations. In both sources, we observe large changes in the spin-down torque up to a factor of ~4, which persist for several months. Using long baseline phase-connected timing solutions as well as the overall frequency histories, we construct torque noise power spectra for each SGR. The power spectrum of each source is very red (power-law slope ~-3.5). The torque noise power levels are consistent with some accreting systems on time scales of ~1 year, yet the full power spectrum is much steeper in frequency than any known accreting source. To the best of our knowledge, torque noise power spectra with a comparably steep frequency dependence have only been seen in young, glitching radio pulsars (e.g. Vela). The observed changes in spin-down rate do not correlate with burst activity, therefore, the physical mechanisms behind each phenomenon are also likely unrelated. Within the context of the magnetar model, seismic activity cannot account for both the bursts and the long-term torque changes unless the seismically active regions are decoupled from one another.Comment: 26 pages, 11 figures included, accepted for publication in ApJ, analysis of torque noise power density spectra is revised from previous version and minor text changes were mad

Toward Improving Ambient Volta Potential Measurements with SKPFM for Corrosion Studies

Scanning Kelvin probe force microscopy (SKPFM) is used in corrosion studies to quantify the relative nobility of different microstructural features present within complex metallic systems and thereby elucidate possible corrosion initiation sites. However, Volta potential differences (VPDs) measured via SKPFM in the literature for metal alloys exhibit large variability, making interpretation and application for corrosion studies difficult. We have developed an improved method for referencing SKPFM VPDs by quantifying the closely related work function of the probe relative to an inert gold standard whose modified work function is calculated via density functional theory (DFT). By measuring and tracking changes in the probe vs. gold VPD, this method compensates for some of the complex effects that cause changes in an individual probe\u27s work function. Furthermore, it provides a path toward direct, quantitative comparison of SKPFM results obtained by different researchers. Application of this method to a Cu-Ag-Ti eutectic braze of a steel sample imaged with multiple SKPFM probes of differing compositions led to enhanced repeatability both within and among probe types, as well as enabled the calculation of modified work function values for each of the microstructural constituents present

TiO2 Coatings Formed by Atomic Layer Deposition for Enhanced Corrosion Performance of Mg-biomaterials

Magnesium (Mg) alloys have experienced increased attention in the area of biomaterials due to Mg being considered a resorbable biomaterial. Mg alloy implants can potentially be designed to degrade in the body, thus an implant would not remain in the body for longer than is needed to perform its task. Mg and many of its alloys are considered to be biocompatible and non-toxic in the body; however, due to the high rate at which Mg degrades a negative host response is expected. A novel approach to inhibit corrosion rate using thin film coatings on a Mg alloy (AZ31B) via atomic layer deposition (ALD) is proposed. ALD is based on saturated surface reactions on the substrate unlike other thin film deposition techniques such as chemical vapor deposition (CVD) and physical vapor deposition (PVD). Sequentially-performed surface reactions between the substrate and precursor molecules water and titanium tetrachloride (H2O , TiCl4) result in thin film growth of amorphous titanium dioxide (TiO2). TiO2 is grown in an atomic layer-by-layer fashion during ALD allowing sub-nanometer thickness control of growth, with excellent coating uniformity and step coverage. TiO2 coatings and their impact on the corrosion resistance of AZ31B were characterized using atomic force microscopy, scanning electron microscopy, electrochemical impedance spectroscopy, and linear polarization measurements