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1.
Ultrasound examination of a 31-year-old woman at 27 weeks' gestation revealed fetal growth retardation, a bilateral cleft lip and palate, and the absence of median cerebral structures. Chromosome analysis after cordocentesis showed an abnormal karyotype with a structural abnormality of the long arm of chromosome 7: 46,XX,—7,+der(7), t(7;18) (q34;q21.3)mat. The pregnancy was terminated at week 29. The ultrasound findings were confirmed by post-mortem examination, which also revealed a semilobar holoprosencephaly.  相似文献   
2.
When two open-channel flows merge in a three-branch subcritical junction, a mixing layer appears at the interface between the two inflows. If the width of the downstream channel is equal to the width of each inlet channel, this mixing layer is accelerated and is curved due to the junction geometry. The present work is dedicated to simplified geometries, considering a flat bed and a \(90^{\circ }\) angle where two configurations with different momentum ratios are tested. Due to the complex flow pattern in the junction, the so-called Serret–Frenet frame-axis based on the local direction of the velocity must be employed to characterize the flow pattern and the mixing layer as Cartesian and cylindrical frame-axes are not adapted. The analysis reveals that the centerline of the mixing layer, defined as the location of maximum Reynolds stress and velocity gradient, fairly fits the streamline separating at the upstream corner, even though a slight shift of the mixing layer towards the center of curvature is observed. The shape of the mixing layer appears to be strongly affected by the streamwise acceleration and the complex lateral confinement due to the side walls and the corners of the junction, leading to a streamwise increase of the mean velocity along the centerline and a decrease of the velocity difference. This results in a specific streamwise evolution of the mixing layer width, which reaches a plateau in the downstream region of the junction. Finally, the evaluation of the terms in the Reynolds-Averaged-Navier–Stokes equations reveals that the streamwise and normal acceleration and the pressure gradient remain dominant, which is typical of accelerated and rotational flows.  相似文献   
3.
Seed and fruit dispersal along watercourses favours the long-distance migration of invasive species, not only for aquatic or wetland species, but also for terrestrial wind-dispersed plants, like the Japanese knotweed. The present paper aims at investigating the role of watercourses in the dispersal of the knotweed due to its frequent occurrence on riverbanks and production of fertile achenes (type of fruit of the Japanese knotweed). This dispersal occurs along two steps after the fruits deposit on the water surface: floatation first and then sinking towards the bottom of the watercourse. Regarding the first step, the effects of agitation of the water, temperature, surface tension and luminosity on the achenes floatability are experimentally studied. While no influence of luminosity is observed, an increase of temperature greatly decreases the floating time. Floating time also decreases as the contact between water and the fruit is enhanced (through submersion of achenes, agitation of the water or lower surface tension). Regarding the second step, the fall velocity of the fruits in water at rest is measured and appears to be independent of the seed history (floating time). 3D helical motions are systematically observed with constant tangential velocity with respect to the falling velocity. The trajectory of the fruits in a shear flow is then measured and the evolution of their velocity components along the sinking process is discussed. Finally, the contribution of both steps to the long-distance migration of the seeds is estimated.  相似文献   
4.
A case of del(15)(q11q13) was detected in amniotic fluid cell cultures and confirmed by cordocentesis in a 27-year-old woman with a low maternal serum alpha-fetoprotein level. The fetus was shown to have a short femoral length on ultrasonography. This structural chromosome abnormality associated with the prenatal ultrasonographic findings and the morphological characteristics visualized after termination of pregnancy strongly suggest Prader-Willi syndrome.  相似文献   
5.
6.
The authors measured and computed the hydrodynamics and passive scalar dispersion in 90-degree open channel confluences over flat and degraded beds with a dominant upstream or tributary inflow. The present discussion essentially deals with the direction of rotation of the secondary currents, reported for the flat bed configuration with dominant tributary inflow. This rotation direction is indeed surprisingly opposite to the ones reported in the literature, both from calculations and measurements, even if present geometry slightly differs from literature geometries.  相似文献   
7.
用大型底栖动物和ODP系统评价珠江的有机污染   总被引:1,自引:2,他引:1  
采用大型底栖动物需氧有机体百分率ODP(oxygen demander percentage)法对广州珠江前航道、西航道和流溪河的下游段进行河流有机污染评价.结果显示:底栖动物需氧类群密度在三河段间分布确有显著性差异,并根据其ODP可以判断流溪河水质相对较好,水质级别为中国地表水环境质量标准(EQSSW)Ⅳ级,西航道和前航道水质级别都为Ⅴ级.通过测试,这一方法能成功地应用在珠江及流溪河,且该法可以较好地匹配于EQSSW五级评价系统,初步认为ODP系统可以成为一个较好的河流水质生物监测方法.图3表4参13  相似文献   
8.

The aspirations, motivations and choices of individual European citizens are a major driver of the future of global, European and local land use. However, until now no land use study has explicitly attempted to find out how the general public wants to live in the future. This paper forms a first attempt to survey European citizens to understand their desired future lives in relation to consequences for European land use. We used a crowdsourcing experiment to elicit visions from young Europeans about their lives in 2040. Participants completed a graphic novel around carefully selected questions, allowing them to create a story of their imagined future lives in pictures. The methodology worked well, and the sample seemed reasonably representative albeit skewed towards an educated population. In total, 1131 responses from 29 countries were received. Results show a strong desire for change, and for more sustainable lifestyles. There is desire for local and ecologically friendly food production, to eat less meat, to have access to green infrastructure and the ability to cycle to work. However, international travel remains popular, and the desire for extensive food production and owning detached houses with gardens will likely result in complex land use trade-offs. Future work could focus more specifically on quantifying these trade-offs and inform respondents about the consequences of their lifestyle choices. This was a first attempt to use crowdsourcing to understand citizen visions for their lives in the future, and our lessons learned will help future studies improve representativeness and increase responses.

  相似文献   
9.
Kong XQ  Shea D  Baynes RE  Riviere JE  Xia XR 《Chemosphere》2007,66(6):1086-1093
A regression method was developed for the hydrophobicity ruler approach, which is an indirect method for determining the octanol/water partition coefficients of very hydrophobic compounds. Two constants introduced into the mathematical model were obtained by regression of the absorption data sampled before the partition equilibrium. A water miscible organic solvent was used to increase the solubility of the very hydrophobic compounds in the aqueous solution so that the hydrophobicity scale was reduced and the equilibration was accelerated. Polydimethylsiloxane/methanol aqueous solution and a series of 21 polychlorinated biphenyls (PCBs) were used to demonstrate the regression method. The PCB compounds with known experimental logK(o/w) values served as reference compounds, while the PCB compounds without known logK(o/w) values were determined. The distribution coefficients (logK(p/s)), uptake and elimination rate constants were obtained from the two regression constants for each compound (reference or unknown). The correlation of the logK(p/s) values of the reference PCB compounds with their logK(o/w) values was linear (logK(o/w)=2.69logK(p/s)+0.76, R(2)=0.97). The logK(o/w) values were compared with literature values and suggested that some values from the literature far off the calibration line could be inaccurate. The critical experimental factors, the merits of the regression method were discussed.  相似文献   
10.
Lateral cavities are major storage zones in riverine environments for which the mass exchanges with the main stream strongly impact the characteristics of the habitat in these dead zones. An experimental work is presented here with a controlled main stream and a connected open-channel lateral cavity to assess the processes responsible for these exchanges and to quantify the exchange capacities. In a first step, the measurements of passive scalar transport allow us to identify the physical processes involved in the exchange of mass from the main stream and its spreading within the cavity. In a second step, the quantitative mass exchange coefficient, representative of the exchange capacity, is measured for 28 flow and cavity configurations. The sensibility analysis to the governing parameters proposed by the dimensional analysis then reveals that changing the geometric aspect ratio of the cavity does not affect the exchange coefficient while increasing the normalized water depth or decreasing the Reynolds number of the main stream tend to increase this coefficient. Indeed, these parameters modify both the growth rate of the mixing layer width at the interface and the amplitude of the alternating transverse velocity across the interface, thus affecting the exchange capacities from the main stream to the cavity.  相似文献   
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