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41.
Angstrom-resolution atomic force microscope images of Langmuir-Blodgett monolayers and multilayers of cadmium arachidate in air and under water show a dramatic change from a disordered arrangement to a crystalline lattice by the addition or removal of a single layer of molecules. The disordered surface is less stable than the ordered one to mechanical stresses such as atomic force microscopy tip forces or at the air-water contact line during contact angle measurements. The difference in the degree of order in the alkyl chains is attributed to the strong attractive interaction between headgroups in the presence of the divalent cation. 相似文献
42.
Characterization of T cell receptor gamma chain expression in a subset of murine thymocytes 总被引:43,自引:0,他引:43
A M Lew D M Pardoll W L Maloy B J Fowlkes A Kruisbeek S F Cheng R N Germain J A Bluestone R H Schwartz J E Coligan 《Science (New York, N.Y.)》1986,234(4782):1401-1405
While much information exists about the structure and function of the clonally distributed T cell receptor (TCR) alpha beta heterodimer, little is known about the gamma protein, the product of a third rearranging TCR gene. An antiserum to a carboxyl-terminal peptide common to several of the murine gamma chain constant regions and a monoclonal antibody to the murine T3 complex were used to identify products of this TCR gene family in a subpopulation of Lyt2-, L3T4- thymocytes. This subpopulation does not express TCR alpha or full-length TCR beta messenger RNA. The gamma chain is a 35-kilodalton (kD) protein that is disulfide-bonded to a 45-kD partner and is associated with the T3 complex. Analysis of the glycosylation pattern of this thymic gamma chain revealed that the major variable region gamma (V gamma) gene transcribed in activated peripheral T cells is absent from this subpopulation. The cells that bear this second T cell receptor may therefore represent a distinct lineage differentiating within the thymus. 相似文献
43.
Suzdak PD Glowa JR Crawley JN Schwartz RD Skolnick P Paul SM 《Science (New York, N.Y.)》1987,235(4793):1127b-1128b
44.
The US food retailing industry continues to concentrate and consolidate. Power in the agriculture, food, and nutrition system
has shifted from producers to processors, and is now shifting to retailers. Currently, only eight food-retailing corporations
control the majority of food sales in the United States. Expanding on previous research by Lyson and Raymer (2000, Agriculture and Human Values 17: 199–208), this paper examines the characteristics of the boards of directors of the leading food retailing corporations
and the indirect interlocks that bind the food retailers into a corporate community.
Rachel
Schwartz
is a PhD Candidate in the Department of Development Sociology at Cornell University. Her research interests are focused on
the relationship between food retailers and food consumers in the United States, especially in regards to the construction
of the concept of “choice.”
Thomas Lyson
was Liberty Hyde Bailey Professor in the Department of Development Sociology at Cornell University. His interests included
the relationship of agriculture and food systems on community economic development and population health. His most recent
book, Civic Agriculture, developed a problem-solving model for food and agriculture issues. Dr. Lyson passed away in December
2006. 相似文献
45.
A series of small cation molybdates, MgMoO(4), MnMoO(4), FeMoO(4), CoMoO(4), NiMoO(4), and ZnMoO(4) with the wolframite structure characteristic of the corresponding tungstates have been synthesized at high pressure and temperature. The high-pressure compounds revert to the ambient pressure modifications if heated in air at 600 degrees C. 相似文献
46.
47.
Schwartz SE 《Science (New York, N.Y.)》1989,243(4892):753-763
Because sources of sulfur and nitrogen oxides distributed broadly across eastern North America have greatly overlapping zones of influence, it is difficult to determine detailed relations between emissions and the resulting acid deposition. Although substantial progress has been made in the past decade in understanding the pertinent atmospheric processes and in describing them in numerical models, because of the complexities of these processes and the wide range of the time and space scales involved, credible source-receptor relations for regional-scale acid deposition are not yet at hand. Consequently, near-term strategies for reducing acid deposition should be based on considerations other than detailed atmospheric source-receptor relations, but with confidence that regional deposition will be reduced equivalently to any reduction in regional emissions. 相似文献
48.
Climate forcing by anthropogenic aerosols 总被引:14,自引:0,他引:14
Charlson RJ Schwartz SE Hales JM Cess RD Coakley JA Hansen JE Hofmann DJ 《Science (New York, N.Y.)》1992,255(5043):423-430
Although long considered to be of marginal importance to global climate change, tropospheric aerosol contributes substantially to radiative forcing, and anthropogenic sulfate aerosol in particular has imposed a major perturbation to this forcing. Both the direct scattering of shortwavelength solar radiation and the modification of the shortwave reflective properties of clouds by sulfate aerosol particles increase planetary albedo, thereby exerting a cooling influence on the planet. Current climate forcing due to anthropogenic sulfate is estimated to be -1 to -2 watts per square meter, globally averaged. This perturbation is comparable in magnitude to current anthropogenic greenhouse gas forcing but opposite in sign. Thus, the aerosol forcing has likely offset global greenhouse warming to a substantial degree. However, differences in geographical and seasonal distributions of these forcings preclude any simple compensation. Aerosol effects must be taken into account in evaluating anthropogenic influences on past, current, and projected future climate and in formulating policy regarding controls on emission of greenhouse gases and sulfur dioxide. Resolution of such policy issues requires integrated research on the magnitude and geographical distribution of aerosol climate forcing and on the controlling chemical and physical processes. 相似文献
49.
50.
Bennett AD McKnight GE Dodkin SJ Simpson KE Schwartz AM Gunn-Moore DA 《Journal of Feline Medicine and Surgery》2011,13(2):152-154
Measuring urine specific gravity (USG) is an important component of urine analysis as it evaluates renal concentrating capability. The objective of this study was to quantify the difference in USG values between a hand-held optical analogue refractometer and a cat-specific digital instrument. Urine samples from 55 cats were assessed. There was a statistically significant difference between these two refractometers (P<0.001), with the optical refractometer (mean USG=1.031) consistently reading higher than the digital refractometer (mean USG=1.027). Results for a random subset of the samples (n=10) were compared with urine osmolality and both the optical and digital instruments demonstrated excellent correlation. While an accurate USG reading is important, it is unlikely that the statistical significance between the two instruments is clinically significant and, therefore, unlikely to result in a change in patient evaluation or treatment plans. While both the digital and optimal refractometers are highly correlated to the urine osmolality, making both devices valid for assessment of USG in clinical practice, this digital device is easier to read and eliminates the variability of subjective interpretation. 相似文献