A simple random path method for the analysis of flow networks

The path of a particle through an ecosystem is modelled as a Markov chain. For a given flow network, powers of the transition matrix are used to calculate the distribution of the particles over the network after each transition. The method may be applied for the definition and calculation of trophic levels in food webs. The algorithm yields the trophic level distribution of species, the species composition of trophic levels, and the path length distribution of output flows. In addition, the network can be described as a linear chain, with the throughflows at each step identified. Data from several ecosystems are analyzed by the method, showing that surprising insights may result.     

Prenatal sonographic signs of possible fetal genital anomalies

The sonographic markers of female and male external genitalia have been documented in early and late gestation. The aim of the present study was to report our experience of possible sonographic markers of fetal genital anomalies. Sonography was performed with a vaginal probe in early gestation and an abdominal sector scanner in advanced gestation. The following genital anomalies were observed: hypospadias, epispadias, ambiguous genitalia, and testicular feminization or Smith-Lemli-Opitz syndrome. It is therefore concluded that prenatal diagnosis of some genital anomalies is now possible.     

Oligohydramnios with amnio-chorionic separation at 15–16 weeks' gestation

Nine patients with oligohydramnios and amnio-chorionic separation were identified out of 7000 women who underwent a vaginal ultrasound examination at 15–16 weeks' gestation. Oligohydramnios was defined as a reduced amount of amniotic fluid, a distance of more than 1 cm between the chorion and amnion, and a good turgor of the amnion without floating membranes or intrauterine sheets. Fetal malformations were observed in all nine cases. In four of six fetuses where chromosomal analysis was available, an abnormal karyotype was found. It is concluded that oligohydramnios in the early second trimester is associated with fetal abnormality.     

Uterine cavity lavage: Adding fish to conventional cytogenetics for embryonic sexing and diagnosing common chromosomal aberrations

This study was undertaken to examine the efficacy for early prenatal diagnosis of uterine cavity lavage at the level of the internal os and to assess the rate of maternal contamination. In phase I, uterine cavity lavage was performed in 38 women scheduled for pregnancy termination between 6 and 12 weeks. In addition to short- and long-term cultures, one-colour FISH (fluorescence in situ hybridization) with Y and X probes was used for fetal sexing. Two-colour FISH was used in all known male fetuses for the assessment of maternal contamination. In phase II, lavage was performed on 16 women. Fetal sex was diagnosed with direct labelled X and Y probes and common numerical chromosomal aberration was attempted with 18 and 21 direct labelled probes. Fetal sexing was successful in all cases in phases I and II. Out of 34 patients in which tissue was obtained, only FISH was done in six. Long-term cell cultures were successful in the other 28 cases, but complete karyotyping in 19 (56 per cent). No chromosomal aberration was found with the direct labelled probes 18 and 21 in FISH. Maternal contamination was assessed to be 5–10 per cent. This simple and easy-to-master technique is very effective in obtaining fetal cells early in pregnancy for genetic diagnosis, especially by FISH. However, the safety of the procedure must be tested in ongoing pregnancies.     

Advanced rescue techniques: lessons learned from the collapse of a building in Nairobi, Kenya

This paper examines the collapse of a five-storey building in Nairobi, Kenya, on 23 January 2006. It draws on reports from local authorities and on debriefings by Israel's Home Front Command (HFC), including information on injury distribution, rescue techniques, and the mode of operation. Most of the 117 people found under the structure were evacuated on the first day to a public hospital, which was overwhelmed by the incident. HFC forces arrived 23 hours after the disaster. At that stage, two people were still buried under the building and special techniques (tunnelling and scalping) were required to secure their evacuation. The two people quickly recovered after a short stay in hospital. Local technology is the preferred option during such events because time is crucial. International cooperation is required when this technology is not available. All of the hospitals in the disaster area, including private facilities, should participate in treating casualties.