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121.
Blacknell D. Freeman A. White R.G. Wood J.W. 《Geoscience and Remote Sensing, IEEE Transactions on》1987,(6):775-782
The synthetic aperture radar (SAR) is an imaging system that achieves high azimuthal resolution by tracking individual point scatterers using their phase histories, with the expected phase history of a particular point scatterer being derived from the assumed motion of the airborne SAR platform. Normally, it is assumed that the platform travels along a straight line path and that the radar pulses are emitted at equal spatial intervals. However, the aircraft carrying the SAR will be susceptible to extraneous across tracl motions and errors in the pulse spacing also may occur. These errors manifest themselves. as two forms of image degradation in the final image. Firstly, the image will be defocused due to an error in the expected quadratic phase history, and secondly, the image will contain geometric distortions due to an error in the linear phase history. An autofocus technique can be used to focus the image and produce a measure of the quadratic phase error that in turn can be used to estimate the geometric distortions that will be present in the final image. These distortions can be independently measured by direct comparison with a map of the imaged area. This paper describes the application of these methods to some real SAR data and discusses the results of the comparison of the measurements of autofocus and geometric distortions in terms of both the likely platform motions present and the viability of predicting geometric distortion using the autofocus measurements. 相似文献
122.
Coryneform bacteria and yeasts of 21 brick cheeses from six German dairies, produced by using undefined ripening cultures, were identified. Arthrobacter nicotianae, Brevibacterium linens, Corynebacterium ammoniagenes, Corynebacterium variabilis and Rhodococcus fascians were found in significant numbers. Out of 148 coryneform isolates 36 could not be identified at the species level. With the exception of a large rennet cheese, the coryneform microflora of rennet and acid cured cheeses were similar, but the cheeses had clearly different yeast populations. Debaryomyces hansenii and Galactomyces geotrichum prevailed in rennet cheeses while Kluyveromyces marxianus and Pichia membranaefaciens were the main species found in acid cured cheese. The dominance of Yarrowia lipolytica probably indicates an improper yeast population, resulting in poor cheese quality. Some of the species identified are potential candidates for designing a defined ripening culture for rennet red smear cheese. 相似文献
123.
Lors d'une réunion ayant eu lieu il y a quelques mois, un sous-groupe technique de la commission de travail CIB W 67 sur la conservation de l'énergie a passé en revue les possibilités et les problémes des pompes de chaleur. La réunion a confirmé que les possibilités des pompes de chaleur sont considérables quant à la conservation de l'énergie et tous les pays sont tellement intéressés que le besoin d'une collaboration dans les recherches s'est intensifié. 相似文献
124.
K.M. Wilcken S.P.H.T. Freeman S. Xu A. Dougans 《Nuclear instruments & methods in physics research. Section B, Beam interactions with materials and atoms》2008,266(10):2229-2232
The new single-stage accelerator mass spectrometer at SUERC can also accept positive ions. Potential benefits of positive ion measurement with suitable ion sources are more convenient sample form, smaller sample size, a variety of available charge states and maybe new applications. We have begun with oxygen isotope analyses to demonstrate destruction of interfering molecules. 相似文献
125.
A Small‐scale Wort rapid Filtration Test (SWIFT) that predicts beer filtration efficiency has been developed. The test is simple, cost effective and correlates with existing beer filtration tests such as beer Vmax membrane (Esser test) and diatomaceous earth (Walton filter) tests. SWIFT has an advantage over existing beer filtration tests as it can be easily incorporated into barley quality laboratories utilising excess wort from extract analyses, thus negating the need for additional sample preparation or to ferment and age beer. Furthermore, the test does not rely on expensive equipment or specially trained laboratory technicians. SWIFT, which may also be used to evaluate degassed beer, is a syringe test that utilises a 13 mm diameter 0.45 μm membrane and is negatively influenced by wort viscosity (P<0.05). It is envisaged that SWIFT may be applied by barley breeding programs for the evaluation of progeny lines to provide a better prediction of beer filtration performance than total wort β‐glucan measurements. In addition, maltsters and brewers could use SWIFT to assess malt samples, and provide early warning of potential beer filtration problems during the brewing process. 相似文献
126.
We investigated the sequential change in the hypervariable region 1 (HVR 1) of hepatitis C virus (HCV) E2/NS1 gene in an infant. He was transfused with 160 mL of blood containing the HCV (0.7 Meq/mL) on the 6th d after birth and subsequently developed chronic viremia. At 16 mo, the HVR1 amino acid sequences of HCV observed in the infant's sera were very similar to those from the donor (his maternal grandfather) on the day of transfusion. However, highly variable amino acid sequences of HVR1 were observed throughout infancy. These results demonstrate that an adaptive response of HCV to evade host immunity seems to occur, as in adult cases, even in early infancy when the ability to produce humoral immunoglobulin is thought to be low. 相似文献
127.
128.
OBJECTIVE: To determine the frequency of characteristics associated with unprotected heterosexual intercourse in HIV infected adults in an urban area. DESIGN: Retrospective comparison of sexual risk transmission behaviour between HIV infected men and women from a drug treatment site and between women from the drug site and HIV infected women from an urban medical centre. METHODS: HIV infected women and men were asked questions on sexual behaviour for a 1 year period before enrollment. The outcome variable was heterosexual risk behaviour (HRB) defined as having vaginal sex at least once in the previous year and not always using condoms. RESULTS: 73% of the drug clinic females, 72% of the drug clinic males, and 42% of the medical centre female engaged in HRB. Using logistic regression analysis, women and men in drug treatment engaged in similar rates of HRB; however, women in drug treatment were four times (95% CI = 2.0-8.3) more likely to engage in HRB risk behaviour than women from the medical centre. CONCLUSION: The data suggest that a surprisingly large portion of HIV infected patients under treatment engaged in HRB, especially former drug users. Without specifically targeted interventions, the heterosexual spread of HIV in urban areas will continue to be a serious problem. 相似文献
129.
The effects of lesions of the medial dorsal thalamic nucleus (MD) on blocking and latent inhibition (LI) of the rat eyeblink response were examined in the present study. Previous work has demonstrated that the cingulate cortex and related thalamic areas are involved in processing conditioning stimuli throughout training. The experiments in the present study tested the hypothesis that disruption of cingulothalamic stimulus processing produced by lesions of the MD would impair 2 types of associative learning that involve decremental changes in attention. In Experiment 1, MD lesions severely impaired blocking. In Experiment 2, NM lesions severely impaired LT. The results indicate that lesions of the NM impair incremental, decremental, or both types of changes in stimulus processing during learning. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
130.