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排序方式: 共有28条查询结果,搜索用时 31 毫秒
1.
The economic burden of the global trade in tobacco   总被引:1,自引:0,他引:1       下载免费PDF全文
H. Barnum 《Tobacco control》1994,3(4):358-361
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2.
In order to improve means for locating unexploded ordnance items (UXO) and significantly discriminating UXO from clutter, it is desired to tag ordnance items before they are delivered. The munition tagging envisioned will make use of current passive radio frequency identification (RFID) tag technology. The tags will provide information on the munition's location and identity when the UXO tag interrogation module is brought nearby. Knowledge of the magnetic field's behavior is essential in understanding the designs required to transmit energy from the above-ground interrogator to the tag and from the tag back to the above-ground receiver. The munition, being a large metal structure in such close proximity to the tags, will affect their operation because of electromagnetic boundary conditions and the tags' specific circuitry. To this end, modeling of the magnetic fields was required. This paper presents the results of this modeling effort and includes experimental findings. The modeling efforts demonstrated that detection depths to 1 m would be achievable, provided the system is magnetically optimized.  相似文献   
3.
The objective of the research described here was to develop a set of predictive models that would be used to show the performance of hydroxypropylcellulose as a pharmaceutical tablet binder. A statistically designed set of experiments was used to relate tablet formulation to functionality. It was found that the binder level affected both hardness and dissolution time. Useful predictive models were generated for tablet hardness and dissolution time as a function of the binder or binder-drug ratio. The optimal formulation can be predicted from this study, and will depend upon the combination of desired hardness and the dissolution time for a particular drug.  相似文献   
4.
High-resolution mapping of oceanic wind fields with skywave radar   总被引:1,自引:0,他引:1  
The direction of the mean surface wind field in the North Pacific Ocean was mapped on September 25 and 26, 1973, over an area of3 times 10^{6}(km)2by OTH-B HF radar. A spatial resolution of 60 km in range and 15 km in cross range was used at points spaced by 150 km in range and 80 km in cross range. Wind directions were inferred from the upwind/downwind first-order Bragg ratio and the measure of the maximum ratio occurring for radial winds at points near each observation.  相似文献   
5.
A critical challenge facing software security today is the dearth of experienced practitioners. Approaches that rely solely on apprenticeship as a method of propagation won't scale quickly enough to address this burgeoning problem, so as the field evolves and establishes best practices, knowledge management can play a central role in encapsulating and spreading the emerging discipline more efficiently. This article is about the kinds of security knowledge that can provide a solid foundation for software security practices.  相似文献   
6.
On quantum fidelities and channel capacities   总被引:2,自引:0,他引:2  
For the discrete memoryless quantum channel, we show the equivalence of two different notions of quantum channel capacity: that which uses the entanglement fidelity as its criterion for success in transmission, and that which uses the minimum fidelity of pure states in a subspace of the input Hilbert space as its criterion. As a corollary, any source with entropy rate less than the capacity may be transmitted with high entanglement fidelity. We also show that a restricted class of encodings is sufficient to transmit any quantum source which may be transmitted on a given channel. This enables us to simplify a known upper bound for the channel capacity. It also enables us to show that the availability of an auxiliary classical channel from encoder to decoder does not increase the quantum capacity  相似文献   
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8.
The purpose of this study was to identify factors at the quarter and cow level that determine whether a quarter remains infected after an intramammary challenge with Staphylococcus aureus Newbould 305. A total of 135 cows were studied. Information on animal characteristics, cow-conformation, cow somatic cell count (SCC), and bacteriology, blood vitamin E levels, serology for retro-viral infections, bovine leukocyte adhesion deficiency-carrier status, and the presence of bovine lymphocyte antigens class I alleles was collected on each animal. All quarters of all cows were then challenged with Staphylococcus aureus Newbould 305. The challenge with S. aureus Newbould 305 resulted in 28 cows (20.7%) that did not establish infection in any of the quarters, 21 (15.6%) cows had 1 quarter infected, 35 (25.9%) had 2 quarters infected, 24 (17.8%) had 3 quarters infected, and 27 (20.0%) had all quarters infected. A higher prechallenge SCC decreased the risk of infection. An infection with Corynebacterium bovis prior to challenge decreased the risk of S.aureus infection. Of the bovine lymphocyte antigen alleles, the presence of the W20A allele proved to be significantly associated with a decreased risk of infection. No other factors proved to be significant.  相似文献   
9.
Meta-linked polyphenyl ethers show considerable promise as high-temperature radiation-resistant lubricants. They are far superior to present-day products in oxidation, thermal and radiation stability, comparing favorably with the most stable aromatics such as poly-phenyls, aromatic silanes, etc. In contrast to other high-melting aromatic compounds, the ethers are liquids with superior viscosity-temperature properties and good lubrication characteristics as measured in laboratory rig tests.

Although the polyphenyl ethers were developed primarily to meet the requirements of future turbo-jet engines, their properties may also be suitable in other fields where extreme conditions of temperature and/or radiation are encountered. Suggested applications include hydraulic fluids and base stocks for greases.  相似文献   
10.
Remote measurements of the spatial mean ocean wind speeds were obtained using Doppler spectra resolved to 0.08 Hz from high-resolution HF skywave-radar backscatter measurements of the ocean surface. A standard deviation of 2.4 m/s resulted from the correlation of observed winds over the ocean and the broadening of the Doppler spectra in the vicinity of the higher first-order Bragg line. This broadening, for Doppler spectra unperturbed by the ionospheric propagation, is proportional to the increase in power caused by higher order hydrodynamic and electromagnetic effects in the vicinity of the Bragg line and inversely proportional to the square root of the radio frequency. A lower bound on the measure of wind speed was established at 5 m/s by the low resolution spectral processing and low second-order power. An upper limit is suggested by the steep slope in the region of the sea backscatter spectrum outside the square root of two times the first-order Bragg line Doppler.  相似文献   
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