Neural tube defects in trisomy 18

Central nervous system anomalies in trisomy 18 are usually confined to structural abnormalities of brain development. Despite the recognized association of neural tube defects and trisomy 18, primary (true) anencephaly is uncommon in the classical trisomy 18 phenotype. A case of anencephaly with trisomy 18, diagnosed prenatally, is presented with a review of the literature of this association.     

Economic assessment of maternal serum screening for Down's syndrome using human chorionic gonadotropin

The effectiveness and costs of prenatal screening programmes for Down's syndrome using maternal serum markers will vary significantly depending on the biological cut-off values chosen in order to select women, at each maternal age, who will be sent for amniocentesis. On the basis of the first French prospective study of human chorionic gonadotropin (hCG) measurement in maternal serum, this paper shows that the screening protocol currently used in France, where hCG cut-off values are defined in order to offer amniocentesis to women of all ages with a 1 percent fetal risk of Down's syndrome, would detect 64·06 per cent of all cases of trisomy 21 at birth and would be highly profitable for the French social security system. On the basis of a representative sample of 100 000 pregnant women, the total costs of screening would reach $8 302 000 but would generate net potential savings of $32 186 000 in terms of life-long costs of care for trisomic 21 children which would be ‘avoided’ by termination of pregnancy following a positive diagnosis of Down's syndrome. Economic assessment shows that cost-benefit analysis would justify lower hCG cut-off values and a higher detection rate of fetal Down's syndrome (74·45 per cent) than the current French protocol. This paper concludes that it is ethical and value-laden issues, such as the consequences for women and couples of false positives and false negatives of screening, rather than economic and financial arguments that may set limits to the utilization of screening for Down's syndrome using maternal serum markers like hCG.     

Evaluating the effect of vehicle impoundment policy on illegal construction and demolition waste dumping: Israel as a case study

Construction and demolition (C&D) waste dumped alongside roads and in open areas is a major source of soil and underground water pollution. Since 2006, Israeli ministry for environmental protection enacted a policy of vehicle impoundment (VI) according to which track drivers caught while dumping C&D waste illegally have their vehicles impounded. The present study attempted to determine whether the VI policy was effective in increasing the waste hauling to authorized landfill sites, thus limiting the number of illegal unloads of C&D waste at unauthorized landfill sites and in open areas. During the study, changes in the ratio between the monthly amount of C&D waste brought to authorized landfills sites and the estimated total amount of C&D waste generated in different administrative districts of Israel were examined, before and after the enactment of the 2006 VI policy. Short questionnaires were also distributed among local track drivers in order to determine the degree of awareness about the policy in question and estimate its deterrence effects. According to the study’s results, in the district of Haifa, in which the VI policy was stringently enacted, the ratio between C&D waste, dumped in authorized landfill sites, and the total amount of generated C&D waste, increased, on the average, from 20% in January 2004 to 35% in October 2009, with the effect attributed to the number of vehicle impoundments being highly statistically significant (t = 2.324; p < 0.05). By contrast, in the Jerusalem and Southern districts, in which the VI policy was less stringently enforced, the effect of VI on the above ratio was found to be insignificant (p > 0.1). The analysis of the questionnaires, distributed among the local truck drivers further indicated that the changes observed in the district of Haifa are not coincident and appeared to be linked to the VI policy’s enactment. In particular, 62% of the truck drivers, participated in the survey, were aware of the policy and 47% of them personally knew a driver whose vehicle was impounded. Furthermore, the drivers estimated the relative risk of being caught for unloading C&D waste in unauthorized sites, on the average, as high as 67%, which is likely to become a deterrent on its own. Our conclusion is that the VI policy appears to have a deterring effect on truck drivers, by encouraging them to haul C&D waste to authorized landfill sites. As we suggest, the research methodology implemented in the study and its results may help policy makers in other regions and countries, which experience similar environment enforcement problem, to analyze policy responses.     

From dumping to sanitary landfills--solid waste management in Israel

To address the problem of solid waste in Israel, the Ministry of the Environment has formulated a policy based on integrated waste management. The policy calls for reduction of waste at source, reuse, recycling (including composting), waste-to-energy technologies, and landfilling. Due to the implementation of this policy, all the large dumps were closed, state-of-the art landfills were built, and recovery rates have increased from 3% in the beginning of the 1990s to almost 20% in 2003. More than 95% of the municipal solid waste is disposed and treated in an environmentally sound manner - in comparison to a mere 10% just a decade ago. The policy was implemented utilizing both enforcement and financial support ("stick and carrot" approach).     

Chemical interactions between amino acid and RNA: multiplicity of the levels of specificity explains origin of the genetic code

The emergence of the genetic code remains an enigma. Proposed mechanisms are based on random, historical, thermodynamic and natural selection. However, they introduce chance as a key factor for overcoming the difficulties encountered by the model. We propose here a model in which three successive levels of chemical specificity generated the nucleotide assignments of amino acids in the genetic code. The first level results from hydrophobic and stereospecific interactions between amino acids and short oligonucleotides (termed oligons). The second and third levels of specificity are determined by conditions of energy transfer from loaded oligons (amino acid-oligomer covalently linked) to formation of phosphodiester bond (second level of specificity) and peptidic bond (third level of specificity), while these reactions are catalyzed by RNA templates. This model is sustained by the relationships observed between dipole moments of the nucleotides (forming the anticodon) and reactivity of the amino acyl linkage of the loaded oligon. Moreover, analysis of modern tRNAs reveals that they were probably generated by loose duplication of the nucleotide sequence forming the oligons, after emergence of the 'genetic code.' Indeed, the similarity of nucleotide composition with that of the anticodon decreases with the tRNA domain's distance from the anticodon, but the acceptor stem is relatively more similar to the anticodon than other stems closer to it. This would be because energy transfer constraints that existed between anticodon and amino acid in prebiotic loaded oligonucleotides still affect the structures of modern tRNA acceptor stems. In the model presented, the genetic code is inherent to the most archaic 'molecular physiology' in protolife, even before emergence of a functional 'protein world.' Simple physical processes, in which a level of specificity is integrated in an emerging meta-structure expressing new properties, generate a parsimonious and realistic explanation of emergence of the genetic code.     

Evaluation of alternative models of commitments and job attitudes of professionals

Different and sometimes contradictory assumptions can be found in the literature about the relationships between the commitments of professionals to their profession and to the employing organization, and the consequences of these relationships for other work attitudes. Two of the basic alternative theoretical formulations are examined and their viability tested on a sample of 1206 accountants. One formulation assumes inconsistency between commitments leading to a commitment dilemma, the other assumes congruity between them. The findings point at the latter formulation as the more viable one, and suggests minor modifications in it to improve its fit with the data. The results demonstrate the need to compare competing models in order to increase theoretical clarity and consistency.