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991.
Three decades ago, the observation that first trimester fetuses with excess fluid accumulation at the back of the neck were more likely to be aneuploid, gave rise to a new era of prenatal screening. The nuchal translucency (NT) measurement in combination with serum biomarkers and maternal age, resulted in the first trimester combined screening (FTCS) program. The introduction of noninvasive prenatal testing (NIPT) over the past decade has introduced the option for parents to receive highly sensitive and specific screening information for common trisomy from as early as 10 weeks gestation, altering the traditional pathway FTCS pathway. The retention of the 11–13-week NT ultrasound remains important in the detection of structural anomalies; however, the optimal management of pregnancies with a low-risk NIPT result and an isolated increased NT measurement in an era of advanced genomic testing options is a new dilemma for clinicians. For parents, the prolonged period between the initial diagnosis in first trimester, and prognostic information at each successive stage of investigations up to 22–24 weeks, can be emotionally challenging. This article addresses the common questions from parents and clinicians as they navigate the uncertainty of having a fetus diagnosed with an increased NT after a low-risk NIPT result and presents suggested approaches to management. 相似文献
992.
Pamela C. Miller Jai E. Shim George W. Holden 《Journal of environmental psychology》1998,18(4):387-398
Although it is commonly recognized that parenting is multiply determined, mechanisms by which the context influences parental behavior have rarely been examined. In this paper, the role of environmental affordances and demands are described and tested in two observational studies. In Study 1, mothers and their 3-year-old children were observed in three settings where affordances and demands differed: the home, park, and laboratory. In Study 2, mothers and their children engaged in three laboratory conditions in which the amount of demands on the mother was manipulated. Several child-rearing variables showed systematic relations with the presence of affordances and demands. It is concluded that affordances and demands play an important role in influencing maternal behavior by acting as environmental cues for place-related behavior. Further, it is proposed that parental perceptions of the immediate context and the recognition of appropriate environmental cues are paramount in understanding the variability of parental behavior across situational contexts. 相似文献
993.
Miriam Fluckiger George D. Jackson Peter Nichols Patti Virtue Adam Daw Simon Wotherspoon 《Marine Biology》2008,154(2):363-372
Fatty acid analysis is an alternative dietary investigation tool that complements the more traditional techniques of stomach
content and faecal analysis that are often subject to a wide range of biases. In applying fatty acid analysis to ecosystem
studies, it is important to have an understanding of the effect diet has on the fatty acid profile of the predator. A feeding
experiment, using crustacean and fish as prey for the European cuttlefish Sepia officinalis, was conducted to evaluate the effect of prey fatty acids on the fatty acid profile of this marine predator. Cuttlefish were
fed on a fish diet for the first 29 days, and then changed to a crustacean diet for a further 28 days. Another group of cuttlefish
was fed on a crustacean diet for the first 29 days, and then changed to a fish diet for a further 28 days. An analysis of
the cuttlefish digestive gland showed that the fatty acid profile reflected that of the prey, with cuttlefish on a crustacean
diet being clearly distinguishable from the cuttlefish on a fish diet. Cuttlefish fed on a fish diet for 29 days prior to
the switch in diet were comparatively higher in 16:0, AA, 20:1ω9, DPA6, DHA, 22:4ω6 and DPA3 than those fed on crustaceans.
Cuttlefish fed on a crustacean diet for 29 days prior to the switch in diet were comparatively higher in 17:1ω8, 18:1ω9, 18:2ω6,
18:1ω7, EPA and 20:2ω6 than those fed on fish. Following a change in diet, the fatty acid profile of the cuttlefish digestive
gland reflected that of the new diet within 14 days. The results confirm that the fatty acid profile of the cuttlefish digestive
gland clearly reflects the profile of its recent diet. It also shows that the digestive gland may not be an organ that accumulates
dietary lipids for long-term storage, but rather is an organ where lipids are rapidly being turned over and potentially excreted. 相似文献
994.
Crini Grégorio Torri Giangiacomo Lichtfouse Eric Kyzas George Z. Wilson Lee D. Morin-Crini Nadia 《Environmental Chemistry Letters》2019,17(4):1645-1666
Environmental Chemistry Letters - Synthetic dyes are an important class of recalcitrant organic compounds that are often found in the environment as a result of their wide industrial use.... 相似文献
995.
Ako AA Shimada J Hosono T Kagabu M Ayuk AR Nkeng GE Eyong GE Fouepe Takounjou AL 《Environmental geochemistry and health》2012,34(5):615-639
Groundwater is the only reliable water resource for drinking, domestic, and agricultural purposes for the people living in the Mount Cameroon area. Hydrogeochemical and R-mode factor analysis were used to identify hydrogeochemical processes controlling spring water quality and assess its usability for the above uses. Main water types in the study area are Ca-Mg-HCO(3) and Na-HCO(3). This study reveals that three processes are controlling the spring water quality. CO(2)-driven silicate weathering and reverse cation exchange are the most important processes affecting the hydrochemistry of the spring waters. While tropical oceanic monsoon chloride-rich/sulfate-rich rainwater seems to affect spring water chemistry at low-altitude areas, strong correlations exist between major ions, dissolved silica and the altitude of springs. In general, the spring waters are suitable for drinking and domestic uses. Total hardness (TH) values indicate a general softness of the waters, which is linked to the development of cardiovascular diseases. Based on Na?%, residual sodium carbonate, sodium adsorption ratio, and the USSL classification, the spring waters are considered suitable for irrigation. Though there is wide spread use of chemical fertilizers and intense urban settlements at the lower flanks of the volcano, anthropogenic activities for now seem to have little impact on the spring water quality. 相似文献
996.
Peter K Van de Water Lidia S Watrud E Henry Lee Connie Burdick George A King 《Ecological applications》2007,17(4):1244-1256
The importance of understanding the role of atmospheric conditions in pollen dispersal has grown in recent years with increased field-testing of genetically modified (GM) crop plants. An atmospheric model was used to characterize wind trajectories at 10 m and 100 m above GM pollen source fields located within a 4452-ha "control" area north of Madras, Oregon, USA, designated by the Oregon Department of Agriculture (ODA). The area was used in 2003 for the growth of GM creeping bentgrass (Agrostis stolonifera) engineered to be resistant to glyphosate herbicide. The presence of the GM gene (CP4 EPSPS) provided a distinct selectable marker for pollen-mediated gene flow to sentinel and resident Agrostis spp. plants. Linkage of GM gene presence with wind flow characteristics over the "control" area became essential to understand the timing and processes leading to long-distance transport of this pollen. Wind trajectories showed a general pattern of northwest to southeast air movement. Trajectory travel distances calculated hourly from 06:00 hours to 15:00 hours during the 2003 pollination period (15 June-15 July) showed movement up to 15 km from the "control" area's center by the first hour. Maximum travel distances increased to 40 and 55 km after two and three hours from release, respectively. Calculated wind trajectory positions corresponded with observed long-distance pollen-mediated gene flow in the seedlings of sentinel and resident plants. The highest correlations were found during the late morning hours. Back-calculated wind trajectories from sentinel and resident locations with GM-gene-positive progeny suggested that most successful fertilizations occurred in the direction of prevailing winds during late June 2003. The occurrence of positive progeny from sentinel plants, upwind of the "control" area during this period, indicated the additional influence of local topography on pollen dispersal. 相似文献
997.
Two types of demographic analyses, perturbation analysis and uncertainty analysis, can be conducted to gain insights about matrix population models and guide population management. Perturbation analysis studies how the perturbation of demographic parameters (survival, growth, and reproduction parameters) may affect the population projection, while uncertainty analysis evaluates how much uncertainty there is in population dynamic predictions and where the uncertainty comes from. Previously, both perturbation analysis and uncertainty analysis were conducted on the long-term population growth rate. However, the population may not reach its equilibrium state, especially when there is management by harvesting or hunting. Recently, there has been an increased interest in short-term transient dynamics, which can differ from asymptotic long-term dynamics. There are currently techniques to conduct perturbation analyses of short-term transient dynamics, but no techniques have been proposed for uncertainty analysis of such dynamics. In this study, we introduced an uncertainty analysis technique, the general Fourier Amplitude Sensitivity Test (FAST), to study uncertainties in transient population dynamics. The general FAST is able to identify the amount of uncertainty in transient dynamics and contributions by different demographic parameters. We applied the general FAST to a mountain goat (Oreamnos americanus) matrix population model to give a clear illustration of how uncertainty analysis can be conducted for transient dynamics arising from matrix population models. 相似文献
998.
Yves Cherel Camille Fontaine George D. Jackson Christine H. Jackson Pierre Richard 《Marine Biology》2009,156(4):699-708
Stable isotopes are increasingly used in the study of trophic interactions of many aquatic animals and most recently cephalopods.
To evaluate the application of the method to squids, it is important to assess isotopic differences among and within consumer
tissues that may confound the resolution of ecological relationships. Inter- and intra-tissue isotopic variation was examined
in 55 individuals of the oceanic squid Todarodes filippovae that were collected at the beginning of April 2000 in the southwestern Indian Ocean (between 44°S, 76°E, and Saint Paul and
Amsterdam islands, 38°S, 78°E). Delipidated soft tissues (mantle, arm, buccal mass, gill and reproductive organs) showed small
δ13C and δ15N differences, which were probably tissue-specific. A lower carbon value was observed in the digestive gland as a consequence
of incomplete lipid removal. Hard tissues, such as beaks and gladii, had lower 15N values than soft tissues, which can be explained by the presence of chitin, a 15N-depleted molecule. Females (n = 38) and males (n = 17) had identical δ13C values, but females showed higher δ15N values than males. The difference was size-related rather than sex-related, however, as females were generally larger than
males. A comparison of similar-sized females and males produced identical nitrogen values. These data suggest dietary shifts
from lower to higher trophic levels during growth, because δ15N values of large T. filippovae were much higher than that of small specimens. As expected, nitrogen values of lower beaks and gladii of large squids increased
from the oldest to the most recently formed region, reflecting the progressive growth of chitinized tissues in parallel with
dietary changes. Sequential sampling along the growth increments of squid beaks and gladii can likely be used to produce a
chronological record of dietary information throughout an individual’s history. 相似文献
999.
Youhua Tang Pius Lee Marina Tsidulko Ho-Chun Huang Jeffery T. McQueen Geoffrey J. DiMego Louisa K. Emmons Robert B. Pierce Anne M. Thompson Hsin-Mu Lin Daiwen Kang Daniel Tong Shaocai Yu Rohit Mathur Jonathan E. Pleim Tanya L. Otte George Pouliot Jeffrey O. Young Kenneth L. Schere Paula M. Davidson Ivanka Stajner 《Environmental Fluid Mechanics》2009,9(1):43-58
A sensitivity study is performed to examine the impact of lateral boundary conditions (LBCs) on the NOAA-EPA operational Air
Quality Forecast Guidance over continental USA. We examined six LBCS: the fixed profile LBC, three global LBCs, and two ozonesonde
LBCs for summer 2006. The simulated results from these six runs are compared to IONS ozonesonde and surface ozone measurements
from August 1 to 5, 2006. The choice of LBCs can affect the ozone prediction throughout the domain, and mainly influence the
predictions in upper altitude or near inflow boundaries, such as the US west coast and the northern border. Statistical results
shows that the use of global model predictions for LBCs could improve the correlation coefficients of surface ozone prediction
over the US west coast, but could also increase the ozone mean bias in most regions of the domain depending on global models.
In this study, the use of the MOZART (Model for Ozone And Related chemical Tracers) prediction for CMAQ (Community Multiscale
Air Quality) LBC shows a better surface ozone prediction than that with fixed LBC, especially over the US west coast. The
LBCs derived from ozonesonde measurements yielded better O3 correlations in the upper troposphere. 相似文献
1000.
Simultaneous carbon, nitrogen and phosphorous removal from municipal wastewater in a circulating fluidized bed bioreactor 总被引:4,自引:0,他引:4
In this study, the performance of the circulating fluidized bed bioreactor (CFBB) with anoxic and aerobic beds and employing lava rock as a carrier media for the simultaneous removal of carbon, nitrogen and phosphorus from municipal wastewater at an empty bed contact time (EBCT) of 0.82 h was discussed. The CFBB was operated without and with bioparticles' recirculation between the anoxic and aerobic bed for 260 and 110 d respectively. Without particles' recirculation, the CFBB was able to achieve carbon (C), total nitrogen (N) and phosphorous (P) removal efficiencies of 94%, 80% and 65% respectively, whereas with bioparticles' recirculation, 91%, 78% and 85% removals of C, N and P were achieved. The CFBB was operated at long sludge retention time (SRT) of 45-50 d, and achieved a sludge yield of 0.12-0.135 g VSS g COD(-1). A dynamic stress study of the CFBB was carried out at varying feed flow rates and influent ammonia concentrations to determine response to shock loadings. The CFBB responded favourably in terms of TSS and COD removal to quadrupling of the feed flow rate. However, nitrification was more sensitive to hydraulic shock loadings than to doubling of influent nitrogen loading. 相似文献