Effects of a (n−3) polyunsaturated fatty acid-deficient diet on profiles of serum vitellogenin and lipoprotein in vitellogenic trout (Salmo gairdneri)

During the 6 months of vitellogenesis, 3-year-old female trout (Salmo gairdneri) were fed either an enriched (E) or an (n−3) polyunsaturated fatty acid (PUFA)-deficient (D) diet; serum vitellogenin (VG) and lipoproteins (d<1.21 g/ml) were analyzed at the third month of vitellogenesis (September) and at ovulation (December). The serum content of high density lipoproteins (HDL), the major protein class, maintained a mean value of 1500 mg/dl at both stages and with both diets. On the contrary, very low density lipoproteins (VLDL) were 90% higher during vitellogenesis than at spawning time, whereas excess vitellogenin circulated at this period (6580 mg/dl serum with diet E). The diet deficient in (n−3) lowered serum vitellogenin content by 16% in September and by 26% in December. The degree of (n−3) PUFA incorporation moderately decreased in low density lipoproteins (LDL) and in HDL with the (n−3)-deficient diet. The effect was more pronounced for 20∶5. On the other hand, essential 22∶6 was incorporated into vitellogenin at the same rate in September as in December with diet E (23% and 25%, respectively), whereas after a 3-month deficiency, the percentage fell to 12%; this percentage rose again to 19% at spawning time. These findings show that, although stored (n−3) PUFA were not exhausted after a 6-month dietary deficiency, the incorporation of essential fatty acids (EFA) into vitellogenin during the early stages of oogenesis was low, suggesting changes in egg composition that may influence hatching.     

Diet during pregnancy in relation to birthweight in healthy singletons

Both epidemiological and experimental studies have shown that physical exercise deserves particular attention in any consideration of approaches to the prevention of neoplasia, especially since it also exerts consistent beneficial effects on the other major chronic diseases prevalent in the Western world, atherosclerosis and non-insulin dependent diabetes mellitus (NIDDM). The organ sites for which strong evidence has been gained for a protective influence of exercise or an elevated risk with a sedentary existence include the colon, prostate, breast and endometrium. The underlying mechanisms appear to centre on the hormones insulin and oestrogen, serum elevation of both of these endocrine factors being associated with increased risk of neoplastic development. The immense potential benefit of an increased level of exercise in the general population suggests that commensurate measures should be taken in the field of cancer education.     

Insulin-like growth factor-I and binding protein-3 in relation to childhood leukaemia

The aetiology of most cases of childhood leukaemia remains unknown, but several studies have indicated that increased birthweight and height are risk factors for the disease. Since insulin-like growth factor-I (IGF-I) mediates the effect of growth hormone and has been positively associated with prostate cancer, we have evaluated the role of this hormone and its principal binding protein, IGFBP-3, in the aetiology of childhood leukaemia. Incident cases of childhood leukaemia from those recorded by a national network of childhood oncologists were enrolled in our study. Controls were children hospitalised for acute conditions of no more than moderate severity with matching for gender, age and maternal place of residence. Blood measurements of IGF-I and IGFBP-3 were undertaken using commercially available radioimmunoassays. Serum IGF-I values decreased by about 1.7% per month, and the rate of decline was higher, though not significantly so, among cases (2.1% per month) than among controls (1.4%). There was no significant association between IGF-I and the likelihood of childhood leukaemia, but an increment of 1 microg/ml of IGFBP-3 was associated with a substantial and statistically significant reduction of childhood leukaemia by 28% (95% confidence interval 7% to 45%). Because IGFBP-3 is essentially a binding protein, we interpret our findings as indicating that bioavailable IGF-I may play an important role in the aetiology of childhood leukaemia. The much smaller quantities and the inherent instability of IGF-I in the blood in comparison to those of IGFBP-3 are likely to hinder documentation of an underlying positive association of IGF-I with the disease.     

Quantitative analysis of a certified e-mail protocol in mobile environments: A probabilistic model checking approach

Formal analysis techniques, such as probabilistic model checking, offer an effective mechanism for model-based performance and verification studies of communication systems’ behavior that can be abstractly described by a set of rules i.e., a protocol. This article presents an integrated approach for the quantitative analysis of the Certified E-mail Message Delivery (CEMD) protocol that provides security properties to electronic mail services. The proposed scheme employs a probabilistic model checking analysis and provides for the first time insights on the impact of CEMD’s error tolerance on computational and transmission cost. It exploits an efficient combination of quantitative analysis and specific computational and communication parameters, i.e., the widely used Texas Instruments TMS320C55x Family operating in an High Speed Downlink Packet Access (HSDPA) mobile environment, where multiple CEMD participants execute parallel sessions with high bit error rates (BERs). Furthermore, it offers a tool-assistant approach for the protocol designers and analysts towards the verification of their products under varying parameters. Finally, this analysis can be also utilized towards reliably addressing cost-related issues of certain communication protocols and deciding on their cost-dependent viability, taking into account limitations that are introduced by hardware specifications of mobile devices and noisy mobile environments.     

Clustering‐based scheduling: A new class of scheduling algorithms for single‐hop lightwave networks

In wavelength division multiplexing (WDM) star networks, the construction of the transmission schedule is a key issue, which essentially affects the network performance. Up to now, classic scheduling techniques consider the nodes' requests in a sequential service order. However, these approaches are static and do not take into account the individual traffic pattern of each node. Owing to this major drawback, they suffer from low performance, especially when operating under asymmetric traffic. In this paper, a new class of scheduling algorithms for WDM star networks, which is based on the use of clustering techniques, is introduced. According to the proposed Clustering‐Based Scheduling Algorithm (CBSA), the network's nodes are organized into clusters, based on the number of their requests per channel. Then, their transmission priority is defined beginning from the nodes belonging to clusters with higher demands and ending to the nodes of clusters with fewer requests. The main objective of the proposed scheme is to minimize the length of the schedule by rearranging the nodes' service order. Furthermore, the proposed CBSA scheme adopts a prediction mechanism to minimize the computational complexity of the scheduling algorithm. Extensive simulation results are presented, which clearly indicate that the proposed approach leads to a significantly higher throughput‐delay performance when compared with conventional scheduling algorithms. We believe that the proposed clustering‐based approach can be the base of a new generation of high‐performance scheduling algorithms for WDM star networks. Copyright © 2008 John Wiley & Sons, Ltd.     

Nutrients fixation by algae and limiting factors of algal growth in flooded rice fields under semi-arid Mediterranean conditions: case study in Thessaloniki plain in Greece

The aim of this study is to assess the fixation of the major nutrients C, N, P, Ca, Mg, K, Na by algal biomass produced in the rice fields of Thessaloniki plain in Greece under semi-arid Mediterranean conditions and to evaluate the limiting factors for their growth. Measurements were performed in experimental rice-field following the regional conventional practices (C–H treatment): (a) direct sowing, (b) continuous flooding with few intermissions, (c) use of nitrogen fertilizers at 176 kg N ha^?1, and (d) application of herbicides (active ingredients benzofenap and clomazone). Herbicides were not applied in a small part of the field isolated by bunds (C–NH treatment) in order to assess possible limiting effects of herbicides on algae growth. Climatic data, measurements of rice crop characteristics and water quality of the ponded water in the C–H part of the experimental field were also obtained in order to assess the limiting effects of light, temperature and nutrients based on a modelling approach. Green algae were found to be dominant in the specific system. Considering the two treatments, the results showed that herbicides did not affect algae growth probably due to the short period of exposure followed by the continuous flooding. Nutrients fixation by algae for C–H followed the order C (52.1 %) > Ca (5.6 %) > K (3.5 %) > N (2.4 %) > Mg (0.3 %) ≈ Na (0.3 %) > P (0.24 %) with a final dry biomass production at 1,118 kg ha^?1. Based on the measurements and model simulations the most limiting factors under the regional conventional practices of rice cultivation were the temperature at the initial and final stage of rice growing season, the light when the leaf area index of rice was >2 and phosphorus concentration in the ponded water. The mean algae growth rate during the flooding period was estimated at 8.2 kg ha^?1 day^?1, while the maximum rate was estimated at 15.9 kg ha^?1 day^?1 at the initial growth stages of rice before the beginning of intense light limitations from rice crop coverage.     

The risk profile of childhood leukaemia in Greece: a nationwide case-control study

The risk profile of childhood leukaemia in Greece was studied through a case-control investigation that included all 153 incident cases of the disease, ascertained throughout the country during 1993 and 1994, and two hospital controls for every case matched for gender, age and place of residence. The data were analysed using conditional logistic regression and the associations are expressed in terms of adjusted odds ratios (OR) and their 95% confidence intervals. Cases were born to mothers of a higher standard education, the OR for an increment of four schooling years being 1.48 (1.17-1.87) and had higher birth weight, the OR for an increment of 500g being 1.36 (1.04-1.77). Pet ownership and birth after a pregnancy with anaemia were associated with increased risk, the ORs being 2.18 (1.14-4.16) and 2.60 (1.39-4.86) respectively. From the frequency analyses, indicative inverse associations were found with birth order, household crowding and previous hospitalization with allergic diseases, whereas indicative positive associations were found with diabetes mellitus during pregnancy and with neonatal jaundice. Substantial or significant elevations were not found with respect to maternal smoking and coffee drinking during pregnancy, diagnostic radiography and ultrasonographic examinations or blood transfusions. A significant inverse association with maternal consumption of alcohol could be due to multiple comparisons, but a detrimental effect can probably be excluded. A non-significant positive association with total shots of viral vaccinations and a weak non-significant inverse association with breast feeding were also found. We interpret the findings of this study as being compatible with acute childhood leukaemia being linked with delayed development of herd immunity to fairly common infectious agents, in conjunction with accelerated perinatal and early post-natal growth.     

Time-Aware Web Users' Clustering

Web users' clustering is a crucial task for mining information related to users' needs and preferences. Up to now, popular clustering approaches build clusters based on usage patterns derived from users' page preferences. This paper emphasizes the need to discover similarities in users' accessing behavior with respect to the time locality of their navigational acts. In this context, we present two time-aware clustering approaches for tuning and binding the page and time visiting criteria. The two tracks of the proposed algorithms define clusters with users that show similar visiting behavior at the same time period, by varying the priority given to page or time visiting. The proposed algorithms are evaluated using both synthetic and real data sets and the experimentation has shown that the new clustering schemes result in enriched clusters compared to those created by the conventional non-time-aware user clustering approaches. These clusters contain users exhibiting similar access behavior in terms not only of their page preferences but also of their access time.     

Are traffic injuries disproportionally more common among tourists in Greece? Struggling with incomplete data

Data concerning injury hazards among tourists are difficult to obtain because estimates of person–time denominators are rarely available. Existing sources are limited to enumeration of injured or killed persons by nationality and type of injury and the analysis can only rely on proportional indicators. Since 1995, the Regional Hospital in the tourist island of Kerkyra (Corfu) has been covering all types of accidents including road traffic injuries, in the context of the Emergency Department Injury Surveillance System (EDISS). The catchment area of this hospital practically coincides with the island population. About 15% of all accidents are traffic-related among either permanent residents or Greek tourists, but they represent 40% among tourists of foreign nationalities. This is suggestive, but far from conclusive evidence, that traffic injuries may be more common among foreign tourists. There are indications that accidents among foreign tourists overall are slightly more serious. Among Greek tourists, the ratio between peak and non-peak period is similar for non-traffic injuries (7.4) and traffic injuries (6.8), whereas among foreign tourists the corresponding ratio is 9.2 for non traffic injuries and 15.0 for traffic injuries. This pattern is difficult to explain in terms other than an excess risk of traffic injuries among foreign tourists.