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11.
Cynthia J. Sims MD Don T. Fujito Dennis R. Burholt Josef Dadok Harlan R. Giles D. Allan Wilkinson 《黑龙江环境通报》1993,13(6):473-480
We have investigated the ability of high-resolution proton NMR spectroscopy to provide a biochemical constituent screening of human amniotic fluid (AF). Proton NMR spectra were obtained at 300 MHz on AF from patients undergoing amniocentesis in the mid-trimester. Only AF from normal pregnancies (normal fetal karyotype, normal a-fetoprotein levels, normal birth outcome) was used in this study. The AF supernatant was lyophilized and resuspended in deuterated water containing 0.1 mm phosphate buffer and 6.02 mm disodium maleate. Identification of low molecular weight compounds was confirmed by two-dimensional NMR spectra (primarily correlated spectroscopy, or COSY) and standard addition techniques. A broad profile of compounds were ‘NMR visible’ in a single proton spectrum, including creatinine, glucose, organic acids (acetate, citrate, and lactate) and several amino acids (alanine, histidine, leucine, phenylalanine, tyrosine and valine). The proton spectrum was unaffected by prior freezing/thawing of AF samples. We were able to quantify compounds by comparison with an added concentration standard (maleate) at concentrations as low as 30 μm. Good agreement with literature values based on other analytical techniques was obtained. 相似文献
12.
The integrity of social insect colonies is maintained by members recognising and responding to the chemical cues present on the cuticle of any intruder. Nevertheless, myrmecophiles use chemical mimicry to gain access to these nests, and their mimetic signals may be acquired through biosynthesis or through contact with the hosts or their nest material. The cuticular hydrocarbon profile of the myrmecophilous salticid spider Cosmophasis bitaeniata closely resembles that of its host ant Oecophylla smaragdina. Here, we show that the chemical resemblance of the spider does not arise through physical contact with the adult ants, but instead the spider acquires the cuticular hydrocarbons by eating the ant larvae. More significantly, we show that the variation in the cuticular hydrocarbon profiles of the spider depends upon the colony of origin of the ant larvae prey, rather than the parentage of the spider. 相似文献
13.
As part of the Medical Research Council randomized trial of vitamin supplementation in the prevention of neural tube defects (NTDs), maternal serum alpha-fetoprotein (AFP) was available for 19 NTD pregnancies. Each of these was matched with four unaffected controls, by maternal age, participating centre, and duration of sample storage. The samples came from women whose gestational age ranged from 6 to 14 completed weeks. The median AFP level in the affected pregnancies was 1·2 multiples of the median value in unaffected pregnancies of the same gestational age (95 per cent confidence interval (CI) 0·83–1·59). This confirmed the view that serum AFP measurement is of no practical value in the detection of NTDs in the first trimester of pregnancy. The study also showed that folic acid supplementation, used as a method of preventing NTDs, had no effect on the concentrations of maternal serum AFP up to 14 weeks of pregnancy. 相似文献
14.
Catherine Potvin Petra Tschakert Frédéric Lebel Kate Kirby Hector Barrios Judith Bocariza Jaime Caisamo Leonel Caisamo Charianito Cansari Juan Casamá Maribel Casamá Laura Chamorra Nesar Dumasa Shira Goldenberg Villalaz Guainora Patrick Hayes Tim Moore Johana Ruíz 《Mitigation and Adaptation Strategies for Global Change》2007,12(8):1341-1362
This paper is part of a two-year study to investigate the feasibility of initiating a Clean Development Mechanism (CDM) project
in an indigenous community of Eastern Panamá, Ipetí-Emberá. We use participatory mapping and matrices as well as household
surveys to develop a land-use/land-cover baseline scenario and examine the role of local participation in assessing land-use
change. In Ipetí, land-use change has not occurred in a linear way over the last decades, and our data unveils socio-economic
factors as potential key drivers of change. The concordance that we observed between geographic information and individual
and collective perceptions of land-use change substantiates the possibility of using local knowledge in the establishment
of baseline data for CDM projects. Our calculations suggest that the total carbon (C) stocks in the Tierra Colectiva (TC) of Ipetí-Emberá in 2004 represents a 47% reduction from the estimated C stock at the onset of settlement in the early
1970’s. Results from the participatory assessments predict that, in 2024 and in absence of a CDM project, the C stocks will
decline from 301,859 t C in 2004 to 155,730 t C, which constitutes a reduction of 52%. The scenario with CDM estimates C stocks
of 305,853 t C for 2024, a value slightly superior to the 2004 value. In the TC there is ground to believe that cattle ranching
is likely to become an ever more important activity as the population is young and growing and cannot easily move elsewhere.
Forests tend to be cleared for cultivation while pastures are established on short fallows. Our baseline scenario underlines
the potential for a CDM project to make a significant difference in the future C stocks of this landscape. 相似文献
15.
Sadika M. Baladi Catherine M. Lewis Amitava Ganguly Alvin G. Morrow Lisel R. Shoffner Robert F. Blundy Patrick F. Nakagawa Sara T. Mundy Larry Anderson Karen Adams 《补救:环境净化治理成本、技术与工艺杂志》2003,14(1):5-20
Enhanced bioremediation is quickly developing into an economical and viable technology for the remediation of contaminated soils. Until recently, chlorinated organic compounds have proven difficult to bioremediate. Environmentally recalcitrant compounds, such as polychlorinated biphenyls (PCBs) and persistent organic pesticides (POPs) such as dichlorodiphenyl trichloroethane (DDT) have shown to be especially arduous to bioremediate. Recent advances in field‐scale bioremedial applications have indicated that biodegradation of these compounds may be possible. Engineers and scientists at the Savannah River Site (SRS), a major DOE installation near Aiken, South Carolina, are using enhanced bioremediation to remediate soils contaminated with pesticides (DDT and its metabolites, heptachlor epoxide, dieldrin, and endrin) and PCBs. This article reviews the ongoing remediation occurring at the Chemicals, Metals, and Pesticides (CMP) Pits using windrow turners to facilitate microbial degradation of certain pesticides and PCBs. © 2003 Wiley Periodicals, Inc. 相似文献
16.
TWO STRATEGIES FOR LEARNING A ROUTE IN A DRIVING SIMULATOR 总被引:2,自引:0,他引:2
Vlada Aginsky Catherine Harris Ronald Rensink Jack Beusmans 《Journal of environmental psychology》1997,17(4):317-331
The study of human navigation has long been dominated by the so-called stage theory, i.e. the notion that there are three distinct types of spatial knowledge (landmark, route, and survey knowledge), that are acquired sequentially during spatial learning and development. Based on the results of a route learning experiment in a driving simulator, an alternative to the stage theory is proposed. The authors suggest that subjects follow either a visually dominated or a spatially dominated strategy to solve a route-learning problem. In the visually dominated strategy, subjects base their wayfinding decisions on visually recognizing decision points along a route; the decision points are not integrated into any kind of survey representation. In the spatially dominated strategy, on the other hand, subjects represent the environment as a survey map right from the start; that is, they do not pass through a landmark or route stage. These strategies may be subserved by different cortical areas recently characterized in neurophysiological studies of animals solving maze problems. 相似文献
17.
Allan K Fitzsimmons 《Journal of the American Water Resources Association》1996,32(2):217-227
ABSTRACT: Protection of ecosystems as entities on the landscape has attracted a wide range of support. Ecosystem-based public policies are claimed to be more effective, efficient, and scientifically sound than other approaches to environmental and natural resource policy. The ecosystem concept was never intended to serve as a public policy guide or to determine landscape units for land management purposes. This paper critically examines the use of the ecosystem concept in public policy and land use management and analyzes the proposed rule to manage the National Forest System according to ecosystem management principles. The concept is found to be unsuitable as a basis for guiding environmental and natural resource public policies in general while the proposed rule to manage the national forests according to ecosystem management principles is shown to be incoherent. 相似文献
18.
In this second counterpoint article, we refute the claims of Landy, Locke, and Conte, and make the more specific case for our perspective, which is that ability‐based models of emotional intelligence have value to add in the domain of organizational psychology. In this article, we address remaining issues, such as general concerns about the tenor and tone of the debates on this topic, a tendency for detractors to collapse across emotional intelligence models when reviewing the evidence and making judgments, and subsequent penchant to thereby discount all models, including the ability‐based one, as lacking validity. We specifically refute the following three claims from our critics with the most recent empirically based evidence: (1) emotional intelligence is dominated by opportunistic ‘academics‐turned‐consultants’ who have amassed much fame and fortune based on a concept that is shabby science at best; (2) the measurement of emotional intelligence is grounded in unstable, psychometrically flawed instruments, which have not demonstrated appropriate discriminant and predictive validity to warrant/justify their use; and (3) there is weak empirical evidence that emotional intelligence is related to anything of importance in organizations. We thus end with an overview of the empirical evidence supporting the role of emotional intelligence in organizational and social behavior. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
19.
20.
Beulke S van Beinum W Brown CD Mitchell M Walker A 《Journal of environmental quality》2005,34(6):1933-1943
There is evidence that degradation of pesticides in simple laboratory systems may differ from that in the field, but it is not clear which of the simplifications inherent in laboratory studies present serious shortcomings. Laboratory experiments evaluated several simplifying assumptions for a clay loam soil and contrasting pesticides. Degradation of cyanazine [2-(4-chloro-6-ethylamino-1,3,5-triazin-2-ylamino)-2-methylpropiononitrile] and bentazone [3-isopropyl-1H-2,1,3-benzothiadiazin-4(3H)-one 2,2-dioxide] at fluctuating temperature and moisture was predicted reasonably well based on parameters derived from degradation under constant conditions. There was a tendency for slower degradation of cyanazine and bentazone in soil aggregates of 3 to 5 mm in diameter (DT50 at 15 degrees C and 40% maximum water holding capacity of 25.1 and 58.2 d, where DT50 is the time for 50% decline of the initial pesticide concentration) than in soil sieved to <3 mm (DT50 of 19.1 and 37.6 d), but the differences were not significant for most datasets. Degradation of cyanazine, isoproturon [3-(4-isopropylphenyl)-1,1-dimethylurea], and chlorotoluron [3-(3-chloro-p-tolyl)-1,1-dimethylurea] was measured in soil amended with different amounts of lignin. The effect of lignin on degradation was small despite considerable differences in sorption. The DT50 values of cyanazine, isoproturon, and chlorotoluron were 16.2, 18.6, and 33.0 d, respectively, in soil without lignin and 19.0, 23.4, and 34.6 d, respectively, in soil amended with 2% lignin. Degradation of bentazone and cyanazine in repacked soil columns was similar under static and flow conditions with 50.1 and 47.2% of applied bentazone and 74.7 and 73.6% of applied cyanazine, respectively, degraded within 20 d of application. Thus, the assumptions underpinning laboratory to field extrapolation tested here were considered to hold for our experimental system. Additional work is required before general conclusions can be drawn. 相似文献