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Simulation models are used widely in pharmacology, epidemiology and health economics (HEs). However, there have been no attempts to incorporate models from these disciplines into a single integrated model. Accordingly, we explored this linkage to evaluate the epidemiological and economic impact of oseltamivir dose optimisation in supporting pandemic influenza planning in the USA. An HE decision analytic model was linked to a pharmacokinetic/pharmacodynamics (PK/PD) – dynamic transmission model simulating the impact of pandemic influenza with low virulence and low transmissibility and, high virulence and high transmissibility. The cost-utility analysis was from the payer and societal perspectives, comparing oseltamivir 75 and 150 mg twice daily (BID) to no treatment over a 1-year time horizon. Model parameters were derived from published studies. Outcomes were measured as cost per quality-adjusted life year (QALY) gained. Sensitivity analyses were performed to examine the integrated model's robustness. Under both pandemic scenarios, compared to no treatment, the use of oseltamivir 75 or 150 mg BID led to a significant reduction of influenza episodes and influenza-related deaths, translating to substantial savings of QALYs. Overall drug costs were offset by the reduction of both direct and indirect costs, making these two interventions cost-saving from both perspectives. The results were sensitive to the proportion of inpatient presentation at the emergency visit and patients’ quality of life. Integrating PK/PD–EPI/HE models is achievable. Whilst further refinement of this novel linkage model to more closely mimic the reality is needed, the current study has generated useful insights to support influenza pandemic planning.
Tom Dougherty has recently argued that non-consequentialists cannot accommodate our judgements about acceptable levels of risk-imposition. More specifically, he argues that the following two intuitively plausible claims are inconsistent: (i) that it is impermissible to provide small benefits to many people rather than saving the life of someone else, and (ii) that it is permissible to expose someone to a negligible risk of death in order to otherwise provide this person with a small benefit. Abandoning either principle has significant consequences: rejecting (i) requires rejecting an important argument against consequentialism and consequentialist approaches to beneficence; rejecting (ii) requires radically rethinking the way we live our lives, as we routinely expose individuals to negligible risks of death. This article shows that Dougherty's argument relies on a scope ambiguity involving permissibility. Once this ambiguity is resolved, Dougherty's argument fails.
We present new M and L-dwarfs confirmed through follow-up of 2MASS color-selected objects with the CorMASS near-infrared spectrograph (R ˜ 300) on the Palomar 60-inch telescope as part of a continuing follow-up survey. Most of the objects are bright (Ks < 13).
We present the results of a deep, optical/IR wide field imaging survey of selected fields in the nearby (d~ 140 pc) Taurus star-forming region. We report the discovery of 9 new members with spectral types M5.75–M9.5. We derive an Initial Mass Function encompassing 54% of the known members in Taurus. Comparison with dense regions like the Trapezium Cluster in Orion shows that Taurus has produced x2 less brown dwarfs. We suggest that the lower frequency of brown dwarfs in Taurus may result from the low-density star-forming environment, leading to larger minimum Jeans masses.
The discovery of many cool brown dwarfs similar to Gliese 229B has led to the definition of a new spectral class, the T dwarfs, whose 1–2.5 μm spectra exhibit signatures of CH4 absorption. Two classification schemes have been proposed for these objects by Burgasser et al. and Geballe et al. We discuss and compare these schemes, and describe a joint classification scheme currently in development that closely follows the guidelines of the MK process. We also address future work toward establishing gravity classes, classifying at other wavelengths, and identifying those features that may signify the end of the T spectral class.
We present the results of two imaging surveys for companions to low-luminosity dwarfs, one with Keck to a limiting magnitude of K = 20, and the other with HST to a limiting magnitude of I = 23. No companions were found at separations of 0″.5 to 20″.0, but seven companions were found within 0″.5. Based on sub-stellar evolutionary models, we estimate the companion detection efficiency as a function of mass ratio. This modeling, coupled with the data, place strong upper limits on the mass ratios of unobserved companions. We conclude that no companions exist in the optimal sensitivity regions of both surveys for q > 0.85 (HST), and q > 0.4 (Keck).
This paper describes the status of a new 0.9 – 2.4 μm spectroscopic survey of low-mass stars and brown dwarfs. Flux-calibrated spectra of 30 objects from M6 to T8 have been obtained with a uniform spectral resolution of R=2,000. For the J-band alone, 60 objects have been observed. In addition, we have obtained the first sequence of spectra at R=20,000 (15 km/s) showing the detailed behavior of the J-band potassium doublets over the same range in spectral type. A few sources have been monitored for radial velocity variations, but none have been detected at the ±1–2 km/s level. Preliminary infrared spectral classification indices have been derived and several young brown dwarfs show clear spectral signatures of lower gravity. Our survey will be available on-line in the future.
The characteristics of an X-ray detection system based on an array of parabolic reflectors that provide a line-shaped focus will be described. The most recent rocket instrument has an overall length of about two meters and utilizes a pair of thin-window gas-flow proportional counters for detecting the X-rays. The variation of effective aperture with X-ray energy, the amount of scattering from the mirror surfaces, and the quality of the optical focus will be discussed. Estimates of the sensitivity of a larger set of X-ray optics used as a survey system, and when combined with a special grating to form a spectrograph, will be presented.
John Broome argues that fairness requires that claims are satisfied in proportion to their strength. Broome holds that, when distributing indivisible goods, fairness requires the use of weighted lotteries as a surrogate to satisfy proportionally each candidate's claims. In this article, we present two arguments against Broome's account of fairness. First, we argue that it is almost impossible to calculate the weights of the lotteries in accordance with the requirements of fairness. Second, we argue that Broome rules out those methods whose use might provide some resolution to this problem. From these arguments, we conclude that, contra Broome, fairness does not require the proportional satisfaction of claims.
Introduction. Bacterial canker, caused by Pseudomonas
syringae pv. syringae, is a damaging disease of stone fruit
worldwide. The effects of rootstock, temperature and incubation duration on bacterial
canker in peach were assessed using both field and laboratory inoculation assays.
Materials and methods. Both field and laboratory experiments were conducted
to study the effects of rootstock, temperature and incubation duration on disease severity
in peach. All inoculations were achieved with P. syringae pv.
syringae strain B3A. Bacterial inoculations were applied to 1-year-old
shoots of peach trees [Prunus persica (L.) Batsch]. After inoculation,
the inoculated shoots were allowed to incubate either under field conditions or in a cold
room at different temperatures [constantly at 0 °C, constantly at 14.4 °C, and in a
fluctuating temperature regime of 12 h at 0 °C (night) and 12 h at 14.4 °C (day)] for
excised shoots. The lesions were determined 1 to 6 weeks after inoculation to determine
the effect of incubation duration. Results and discussion. The field
experiment using peach grafted on three rootstocks (Nemaguard, K119-50 and P30-135) showed
that shoots on Nemaguard developed the longest lesions and shoots on K119-50 the shortest
among all three rootstocks. Shoots on Nemaguard had significantly lower bark calcium and
higher nitrogen concentrations than those on K119-50 and P30-135. A negative correlation
was found between lesion length and bark calcium concentration and the [calcium
/ nitrogen] ratio. Laboratory experiments with excised shoots on Nemaguard, K119-50,
P30-135, Lovell and Guardian rootstocks growing in a second orchard showed inconsistent
results. Shoots from Nemaguard developed significantly smaller lesions than those on
K119-50 and P30-135. Shoots on Guardian and Lovell also developed significantly smaller
lesions than those of shoots on K119-50 and P30-135. Temperature fluctuation during
incubation (0 °C to 14.4 °C) had no effect on shoot lesion length compared with those
incubated constantly at 14.4 °C, but produced significantly longer lesions than shoots
incubated constantly at 0 °C. These inconsistent results suggest that, in the absence of
major predisposing factors (i.e., ring nematodes or low soil pH),
rootstocks may play a minor role in peach susceptibility to bacterial canker even under
favorable disease development conditions.
It has been shown that metal ion implantation can harden single crystal sapphire and introduce compressive stresses at the surface, which may lead to an increase in the fracture toughness of the material. This may significantly affect the usefulness of this material as a shatter-resistant optical window in missile applications. In this study, we have examined the extent to which sapphire can be implanted without severely degrading its optical quality by ion beam defect production. Optically-polished single-crystal c-axis sapphire was implanted with 150 keV Cr+, Ti+, and Si+ ions to doses of 0.3 – 3.0 × 1017 ions/cm2 at both room temperature and at 800 °C, to measure the optical effect of in situ annealing. Rutherford backscattering spectrometry showed evidence of implant species migration only in the case of Ti implanted at high temperatures; all other implant profiles were Gaussian. The optical transmittance of the sapphire was examined using visible spectrum transmission and Fourier Transform Infrared Spectroscopy. Si implantation resulted in a 10 % reduction in infrared transmittance at the highest ion dose, but this was reduced to 6 % when the implantation was done at high temperature. Both Cr and Ti implantation reduced the sapphire IR transmittance (by 16 % and 42 %, respectively) , but the effect of implantation temperature on transmittance was different. High temperature during implantation increased the transmittance of Cr-implanted samples, but further darkened Ti-implanted samples. Photon tunneling and atomic force microscopy showed that both Ti and Cr implantation roughened the surface of the material.
We present here a study of the effect of Fe doping and hydration on the NMR, EPR spectra and Tc of slowly and rapidly cooled Y-1 Ba2Cu3O6+x Superconductor. The g-values of the EPR signals are related to Cu2+ ions in six-fold coordination. Tc is suppressed 10–20°C due to changes in processing conditions and the addition of Fe. The 89Y MAS-NMR spectra show that Y is more shielded (more ionically bonded) in the slowly cooled sample than in the rapidly cooled sample and the hydrated slowly cooled sample is less shielded. The effect of hydration on 89Y chemical shift is consistent with the presence of protons near the Y.
Combined Raman, 29Si NMR and reactivity studies of silica gels indicate that dehydroxylation of the silica surface results in cyclotrisiloxane species with reduced Si-O-Si bond angles and altered acid/base characteristics. XPS experiments indicate that the expected 0.35 eV shifts in Si2p and O1s binding energies due to the reduced bond angles are hidden within broad peaks due to the remaining hydroxyls. Additional Si2P, OlS, and ClS peaks are also observed and are postulated to result from preferential adsorption of extrinsic C-containing species on sites with enhanced acid/base properties.
Polycrystalline Si (poly-Si) waveguides offer design flexibility and multilayered structures in Si-integrated photonic devices. However, as-deposited poly-Si surfaces are rough compared with single-crystalline Si, and a rough surface causes significant waveguide scattering loss at the surface. In this study, surface smoothing of poly-Si waveguides with a gas-cluster ion beam (GCIB) was demonstrated as a new smoothing technique. As the GCIB process is a directional ion-beam process, in principle it can be applied not only to plane surfaces but also to three-dimensional or non-flat structures, such as waveguide ridges.
The initial average roughness of as-deposited poly-Si films (625°C, 1 μm thick) ranged from 15 nm to 22 nm, and the grain sizes were distributed from 0.2 to 0.4μm. This rough surface was dramatically smoothed to a roughness of 1.5 nm by Ar cluster ion irradiation. From the relation between the sputtered depth and the surface roughness, the sputtered depth must be greater than the height difference of the roughness (peak-to-valley) to obtain smooth surfaces. Optical transmission losses at λ =1.54 μm were measured using cutback measurement from samples before and after the smoothing by GCIB. After surface smoothing with GCIB, the optical loss decreased from 85 dB/cm to 54 dB/cm.
Surface processing of microelectronic materials by bombardment with nanoparticles of condensed gases (i.e., clusters) in the form of an ion beam, makes possible etching and smoothing of those surfaces to very high figures of merit. As this is not possible with any conventional ion method, gas-cluster ion-beam systems have great potential in manufacturing. The formation of gas clusters and their collision with surfaces provides an interesting arena for novel physics and surface science. This paper outlines a physical model for the clusters and surface interactions, and provides examples of surface processing. In particular, the reduction of surface roughness while etching by cluster-ion bombardment is illustrated for various materials utilized in microelectronics.
During the absorption of a laser pulse of moderate length, the leading edge can experience excited state absorption out of the first singlet state. The measurement of this excited state absorption spectrum can only be accurately probed using short pulse pump-probe techniques. Specifically, we examine the excited state absorption of AF-380 in THF using ultrafast transient white light absorption spectroscopy (TWLA). This material has been the focus of several investigations due to it's purported large two-photon absorption cross-section, the discrepancies between long and short pulse measurements, and it's use in holographic twophoton induced photopolymerization. It is believed that a substantial excited state absorbance can account for the difference in two-photon cross section measurements. It is also possible that this excited state exhibits coherence for time scales that can affect further absorption of longer pump pulses. We examine the transient absorption of this species, as well as polarization and free carrier effects and discuss the possible implications with regards to measurement techniques.
Phosphorescence studies of reverse saturable absorption materials (RSA) are discussed. Absorption and emission measurements of an RSA material, specifically Zinc 2,3,7,8,12,13,17,18-octabromo-5,10,15,20-tetraphenylporphyrin (ZnOBP), are performed in a proprietary host polymer. Spectra are analyzed to estimate the relative energy level of the first triplet state of ZnOBP with respect to the ground state.
To understand the properties of light-sensitive compounds used in optical limiters having photoinduced charge transfer mechanisms, we have investigated the photophysics of a series of di(2-thienyl-3,4–butyl)polyenes. Spectroscopic measurements were obtained as a function of the number of double bonds(n = 1–8). From analysis of the bandshape of the emission spectra, we found evidence of vibronic coupling between the S1 and S2 excited states. The degree of coupling increased with solvents of high refractive index. The appearance of the cis band in absorption spectra of dithienyl polyenes having 6–8 double bonds suggested equilibria between scis and s-trans conformors. The cis band intensity increased in lower polarity solvents, implying solvent-induced conformation changes in these dyes. Trends in the data reflected the ordering, energy gap between and mixing of 1Bu* and 1Ag* excited state configurations.
Local structures of high surface area sodium titanate materials have been examined as a function of pH using solid state 17O nuclear magnetic resonance (NMR) spectroscopy. Using 17O NMR, it is possible to determine the relative populations of nonbridging oxygens as well as oxygens bridging between two, three, and four titanium atoms. Results show that protonation of ion exchange sites in titanate materials is not a simple ion exchange process but involves a repolymerization and restructuring of the titanate network. The observed structural changes are consistent with reported phase stabilities of titanates in water as well as with known hydrolysis and condensation reactions.