On Security and Reliability Using Cooperative Transmissions in Sensor Networks

Cooperative transmissions have received recent attention and research papers have demonstrated their benefits for wireless networks. Such benefits include improving the reliability of links through diversity and/or increasing the reach of a link compared to a single transmitter transmitting to a single receiver (single-input single-output or SISO). In one form of cooperative transmissions, multiple nodes can act as virtual antenna elements and provide diversity gain or range improvement using space-time coding. In a multi-hop ad hoc or sensor network, a source node can make use of its neighbors as relays with itself to reach an intermediate node with greater reliability or at a larger distance than otherwise possible. The intermediate node will use its neighbors in a similar manner and this process continues till the destination is reached. Thus, for the same reliability of a link as SISO, the number of hops between a source and destination may be reduced using cooperative transmissions as each hop spans a larger distance. However, the presence of malicious or compromised nodes in the network impacts the benefits obtained with cooperative transmissions. Using more relays can increase the reach of a link, but if one or more relays are malicious, the transmission may fail. However, the relationships between the number of relays, the number of hops, and success probabilities are not trivial to determine. In this paper, we analyze this problem to understand the conditions under which cooperative transmissions fare better or worse than SISO transmissions. We take into consideration additional parameters such as the path-loss exponent and provide a framework that allows us to evaluate the conditions when cooperative transmissions are better than SISO transmissions. This analysis provides insights that can be employed before resorting to simulations or experimentation.     

Cytologic diagnosis and subtyping of rhabdomyosarcoma

Ornithine transcarbamylase (OTC) deficiency is an X-linked disorder of urea synthesis. Among females who carry a mutant OTC allele, there is a wide range of phenotypic variability, ranging from apparent normality to a severe onset and the resulting profound neurologic impairment observed in hemizygous males. This study was designed to define the phenotypic variability of OTC deficiency in ostensibly healthy carrier females and to compare them to noncarrier females from their own and other families. One hundred seventy-five women from 89 families participated in this study. Each completed a mailed questionnaire, allopurinol testing, and fasting plasma amino acid determinations. OTC carrier status was determined by pedigree analysis, allopurinol test results, and/or DNA mutation analysis. Overall, 79 women were identified as carriers of a mutant OTC allele (60 proband mothers, 19 relatives), and 96 women (32 proband mothers, 64 female relatives) were determined to be noncarriers. Comparison of biochemical phenotypes indicated that carriers and noncarriers do not differ in daily urinary creatinine excretion, but that carriers excrete significantly less urea nitrogen and total nitrogen, reflecting their significantly lower historically reported daily protein intake. Carriers had significantly higher levels of fasting plasma glutamine and alanine, and significantly lower levels of citrulline and arginine compared with noncarriers. Carriers and noncarriers reported similar demographic characteristics, anthropometric measurements, level of education, and medical and pregnancy histories. There was no indication of increased incidence of migraine headaches among carriers. Thus, we found no evidence that asymptomatic adult female OTC heterozygotes are at increased risk for previously unidentified health problems apart from an unknown risk for hyperammonemic encephalopathy as occurred in 3 of the carriers in this study. Because these episodes appear to be related to physiologic stress (fracture, parturition), it would seem medically prudent for carriers to be aware of this risk.     

Determination of biogenic amines in sucuk

The biogenic amines content of sucuk (Turkish dry fermented sausage) were determined on 30 samples obtained from retail markets and butchers in Turkey. Also, pH and a_w values, microbiological properties, and NPN levels of these samples were analyzed. The most important biogenic amines were tyramine (range 2.4–676 mg/kg), followed by putrescine varied from not detected to 364 mg/kg. Histamine content was under 50 mg/kg in 80% of the samples while it was over 100 mg/kg in only one sample. Tryptamine was detected in 16 of 30 samples in the range of 1.2–82.3 mg/kg.

Lactic acid bacteria, Micrococcus/Staphylococcus and Enterobacteriaceae counts of samples varied from 2.84 to 8.85 log cfu/g, <2.00 to 6.74 log cfu/g, and <2.00 to 5.04 log cfu/g, respectively. pH values were varied between 4.53 and 6.29 while water activity (a_w) were measured to be between 0.761 and 0.960. NPN values were determined to be between 1.47% and 4.10%. Generally, total amine content was high in samples that had high NPN levels.     

Investigation of Fe content in Cu–Al–Ni Shape Memory Alloys

Polycrystalline Cu–Al–Ni–Fe-based shape memory alloys with different chemical composition were produced in an arc-melting furnace under an argon atmosphere. Homogenized and aged specimens were prepared for multiple analyses. The temperatures of reversible martensitic transformations, namely A_s, A_f, M_s, M_f, A_max and ΔH enthalpy values were determined by a DSC device. The phase transition analysis from the room temperature to 850°C was undertaken by DTA. To characterize the lattice structure, an XRD analysis was conducted, the results of which were confirmed by microstructure images obtained from optical microscope observations.     

Structural characteristics of Hagia Sophia: I—A finite element formulation for static analysis

The historic Hagia Sophia in Istanbul, which held the record as the world's largest domed building for some 800 years, is analysed with a finite element formulation, including the effects of thickness shear deformations and the term z/R$z/R$, to understand its structural behaviour under the action of static loading. The structure, including all essential elements of the system, is modelled by using the same curved trapezoidal finite element with 40 degrees of freedom. Its structural behaviour and its structural load carrying system are demonstrated and the results are compared with those obtained earlier and also with those observed at the structure.     

Structural characteristics of Hagia Sophia: II—A finite element formulation for dynamic analysis

The Hagia Sophia, a 6th century masonry edifice in Istanbul, is analysed with a linear finite element model including thickness shear deformations, the terms z/R, and rotatory inertia effects with consistent mass matrix to provide insight to the structure's behaviour under earthquake loading. The structure, including the primary main dome and supporting system, is modelled by using a two-dimensional model composed of eight-node shell element. The dynamic characteristics of the system are obtained by using the Wilson-θ method, step-by-step integration method, and also by applying the available ground motion data to understand its general structural behaviour in the future earthquakes.     

Effect of usage Urtica dioica L. on microbiological properties of sucuk, a Turkish dry-fermented sausage

The effect of dried-ground Urtica dioica L. on microbiological characteristics of Turkish dry-fermented sausage (sucuk) were investigated. Dried-ground Urtica dioica L. was added to sucuk batters by the rate of 0%, 1%, 3% and 5%, and microbiological analysis were made on the 0, 3, 7, 10 and 14 days of ripening period.

According to the results, both the level of Urtica dioica L. and ripening time had a significant effects on the total aerobic mesophylic bacteria, lactic acid bacteria, Micrococcus/Staphylococcus, yeast-mould and Enterobacteriaceae counts (p<0.01). It was determined that the interactions ripening time × the levels of Urtica dioica L. had a significant effects on the counts of total aerobic mesophylic bacteria, lactic acid bacteria, Micrococcus/Staphylococcus, yeast-mould and Enterobacteriaceae (p<0.01). Enterobacteriaceae count were also found to be under the detectable level (<100 cfu/g) in sucuks (in day 14 of ripening) containing 3% and 5% Urtica dioica L.     

Effect of modified atmosphere and vacuum packaging on some quality characteristics of sliced ‘sucuk’ produced using probiotics culture

The effects of probiotics (Lactobacillus acidophilus and Bifidobacterium lactis), packaging (vacuum, 50% N₂ + 50% CO₂ or 100% CO₂), storage temperature (4 and 10 °C) and storage time (90 d) on lipid oxidation, colour and microbial properties of sliced dry fermented sausage ‘sucuk’, which has a long storage time at low temperatures, was investigated. Probiotic‐added samples showed a significant reduction in the thiobarbituric acid‐reactive substances (TBARS) values compared with a control and starter culture groups. The analysis showed that control groups had the highest pH and that the pH was not affected by packaging or storage temperature. Probiotic use had a significant effect on total aerobic bacteria, lactic acid bacteria and Micrococcus/Staphylococcus counts, and bacterial counts decreased with storage time. The Enterobacteriaceae count was below detectable levels (<2.00 CFU g⁻¹) throughout the storage period. The storage temperatures had no effect on the microbial counts. Packaging had a significant effect on lactic acid bacteria, and the highest value was determined with 50% N₂ + 50% CO₂. The addition of probiotics and the storage time resulted in a significant decrease of colour values (L*, a* and b*). Copyright © 2005 Society of Chemical Industry