The concept of intrinsic value and transgenic animals

The creation of transgenic animals by means of modern techniques of genetic manipulation is evaluated in the light of different interpretations of the concept of intrinsic value. The zoocentric interpretation, emphasizing the suffering of individual, sentient animals, is described as an extension of the anthropocentric interpretation. In a biocentric or ecocentric approach the concept of intrinsic value first of all denotes independence of humans and a non-instrumental relation to animals. In the zoocentric approach of Bernard Rollin, genetic engineering is seen as a morally neutral tool, as long as the animal does not suffer as a result of it. Robert Colwell who defends an ecocentric ethic, makes a sharp distinction between wild animals and domesticated animals. Genetic manipulation of wild species is a serious moral issue, in contrast to genetic manipulation of domesticated species which is no problem at all for Colwell. Both authors do not take the species-specific nature (or telos) of domesticated animals seriously. When domestication is seen as a process between the two poles of the wild animal and the human construct (which can be patented), the technique of genetic manipulation can only be seen as a further encroachment upon the intrinsic value of animals. At the level of molecular biology, the concept of an animal's telos loses its meaning.     

Prenatal diagnosis of pericentric inversion of chromosome no. 17 in a twin pregnancy

Although prenatal genetic diagnosis can usually provide prospective parents with information as to whether their fetus is affected with certain genetic conditions, the presence of twins and the uncertainty about the phenotype of some chromosome variations pose a major dilemma and make genetic counselling very difficult. Here, a case report of an unusual chromosome aberration (pericentric inversion of chromosome no. 17) in a twin pregnancy which was originally suspected to be monoamniotic but later proved to have two sacs was presented.     

人工林经营过程密度最优控制研究

在连续状态动态规划方法建立的人工林种群密度决策模型的基础上，首次提出应用遗传算法优化人工林林分经营过程的间伐时间和主伐时间的最优组合方案，并阐明其数学模型和具体方法。杉木人工林经营过程的密度最优控制方案优化实例表明，用遗传算法优化能收到良好效果。优化结果表明，杉木人工林经营过程中以间伐两次为最优，第一次在１１～１２年，第二次在１５～１８年，而主伐年龄以２５年为最优。     

Reproductive behaviour and prenatal diagnosis following genetic termination of pregnancy in women of advanced maternal age

One hundred and fifty-one women of advanced maternal age who underwent genetic termination of pregnancy (TOP) were studied for their reproductive behaviour and the type of procedure for prenatal diagnosis in a subsequent pregnancy. A total of 59 women (39 per cent) had a further pregnancy. In all continuing pregnancies prenatal diagnosis was performed, of which 75 per cent consisted of chorionic villus sampling (CVS). Reproductive behaviour following a genetic termination was negatively correlated with maternal age and parity. Both reproductive behaviour and the choice to undergo a diagnostic procedure in the next pregnancy were independent of the type of diagnostic procedure in the previous affected pregnancy.     

The effect of the introduction of prenatal diagnosis on the reproductive history of women at increased risk from neural tube defects

The reproductive history of 45 couples at increased risk for neural tube defect (NTD) who came for genetic counselling in 1970 and 1971 were compared with a similar number counselled in 1975 and 1976, when prenatal diagnostic tests were freely offered. They were subsequently interviewed in their homes and had their reproductive history recorded to the end of 1973 and 1978 respectively. Nearly all had a previous child with an NTD and none of the women were pregnant at the time of counselling. The effect of prenatal diagnosis was to speed somewhat the decision about further pregnancies, but the number of couples deciding on no further children and on having further pregnancies were almost identical in the two groups. The average number of pregnancies was 2·8 per family, with only 1·2 surviving children. The pregnancy outcomes are discussed as are the reasons for not attempting further pregnancies in both groups, which included very high risk of recurrence, a surviving spina bifida child, inability to accept the tests or its implications. Ninety per cent of the second group had tests. Their reactions to the tests were favourable but all complained of the waiting time between amniocentesis and obtaining the results. They all would have tests again in any future pregnancy. The reason for women not having prenatal diagnostic tests included inability to accept termination. It is concluded that couples in South Wales decide either to have no more children or to have further pregnancies regardless of tests. but tests speed a decision and enable the women to enjoy the pregnancy after obtaining the results, and that an NTD greatly reduces the number of children per family. A termination for an NTD is much more acceptable to most than an NTD at term. The reasons for this are discussed.     

Adverse outcome in pregnancy following amniotic fluid isolation of Ureaplasma urealyticum

Infections in pregnancy with Ureaplasma urealyticum have been associated with a wide range of adverse outcomes, such as early abortion, stillbirth, prematurity, and neonatal morbidity and mortality. Causality has been difficult to demonstrate secondary to the high prevalence of asymptomatic lower genital tract (LGT) colonization and culture data from inaccessible or potentially contaminated sites. Between 1985 and 1989, 2461 second-trimester genetic amniocenteses were evaluated at the cytogenetics section of the Children's Hospital Medical Center of Akron. All were cultured for the genital mycoplasmas: Mycoplasma hominis and Ureaplasma urealyticum. A total of nine patients were positive, all for Ureaplasma urealyticum, with one patient excluded because of subsequent therapeutic abortion. In addition, complete follow-up data, such as indication for amniocentesis, serum alpha-fetoprotein levels, gestational age at parturition, and out- come of pregnancy, were available on 86 Ureaplasma-negative (U –) patients during an approximate 2-year span within the time-frame of the study. This was in part due to physician response to a questionnaire sent after amniocentesis. Of the eight positive cultures, 100 per cent were associated with an adverse outcome, defined as fetal loss or premature delivery. This was significant compared with the U–group (p<0.001) with a more than eight times greater risk of adverse outcome. Six (75 per cent) resulted in spontaneous miscarriage within 4 weeks of amniocentesis and at less than 21 weeks' gestation. Two (25 per cent) delivered prematurely, with one (12.5 per cent) neonatal death at 24+ weeks. Histological examination of all eight placentae and the seven fetuses revealed a 100 per cent incidence of chorioamnionitis and pneumonia, respectively. In addition, in four of the five cases (80 per cent), cultures were positive for Ureaplasma urealyticum in pure culture from either placenta, fetal lung, or both tissues. The remaining case (20 per cent) was negative for aerobes, anaerobes, and mycoplasmas. The study demonstrates a significant association and supports a causal relationship between isolation of Ureaplasma from mid-trimester amniotic fluid with fetal wastage and premature birth.     

Prenatal diagnosis of genetic microcephaly

True microcephaly can be diagnosed at an early stage of gestation by serial measurements of fetal head growth as demonstrated by this case report in which the diagnosis of genetic microcephaly was made but termination refused. True microcephaly was evident at birth.     

GA优化的湖泊富营养化评价的普适公式探讨

在适当设定富营养化指标的“本底值”情况下,当指标值用于对应“本底值”的相对值表示时,可采用S型曲线描述湖泊富营养化的发展程度,公式中的参数可视为与指标特性无关,采用遗传算法对公式参数优化,得到对多项指标均适用的富营养化程度的指数公式,并提出用广义模糊对比因子赋权新方法计算富营养化综合指数。该评价方法物理意义明确,计算简单,使用方便,具有普适性、可比性和实用性。     

矿井重大灾害危险性评价的改进灰色统计法

用灰色统计理论［１］研究了矿井四大灾害即冒顶、水灾、火灾和瓦斯爆炸的危险性预评价问题，提出了一种新的评价方法──灰色统计综合法。同时，从应用的角度出发对灰色统计的算法作了改进，改进后的算法便于记忆和应用。     

A Two-Stage Particle Swarm Optimization Algorithm for MPPT of Partially Shaded PV Arrays

The power-voltage (P-V) characteristic curves of a PV array are nonlinear and have multiple peaks under partially shaded conditions (PSCs). This paper proposes a novel maximum power point tracking (MPPT) method for a PV system with reduced steady-state oscillation based on a two-stage particle swarm optimization (PSO) algorithm. The grouping method of the shuffled frog leaping algorithm (SFLA) is incorporated in the basic PSO algorithm (PSO-SFLA), ensuring fast and accurate searching of the global extremum. An adaptive speed factor is also introduced into the improved PSO to further enhance its convergence speed. Test results show that the proposed method converges in less than half the time taken by the conventional PSO method, and the power is improved by 33% under the worst PSCs, which confirms the superiority of the proposed method over the standard PSO algorithm in terms of tracking speed and steady-state oscillations under different PSCs.