A Deterministic Polynomial--Time Algorithm for Constructing a Multicast Coding Scheme for Linear Deterministic Relay Networks

We propose a new way to construct a multicast coding scheme for linear deterministic relay networks. Our construction can be regarded as a generalization of the well-known multicast network coding scheme of Jaggi et al. to linear deterministic relay networks and is based on the notion of flow for a unicast session that was introduced by the authors in earlier work. We present randomized and deterministic polynomial--time versions of our algorithm and show that for a network with $g$ destinations, our deterministic algorithm can achieve the capacity in $\left\lceil \log(g+1)\right\rceil$ uses of the network.Comment: 12 pages, 2 figures, submitted to CISS 201

Population structure of Ferosagitta ferox (Chaetognatha) in the northwest coastal waters of the Persian Gulf

Population dynamics of Ferosagitta ferox (Chaetognatha) was carried out in coastal waters of Khur-e-Mussa's Channel in Khuzestan Province, northwest Persian Gulf. Monthly samples were collected with 300km mesh size plankton net in oblique tow from near bottom to surface waters. In total, 7 species of Chaetognaths were identified belonging to 1 class (Sagittoidea), 1 order (Aphragmophora), 2 families (Sagittidae and Krohnittidae) and 4 genera (Aidanosagitta, Ferosagitta, Flaccisagitta and Krohnitta). The identified species included A. Bedford, A. neglecta, F. ferox, Flaccisagitta enflata, F. hexaptera, Krohnitta pacifica and one unknown species. Due to presence and excessive frequency of F. ferox in all samples, we focused on its population variation as an indicator of Chaetognatha. We determined length groups for adult individuals in 4-21mm range with 1mm increments. The year round presence of juvenile and small individuals showed the continuous reproduction of F. ferox with two considerable peaks in March and July. The evaluated recruitment indicated that the species has a low growth rate and a long life cycle

Nanostructured mesoporous carbon as electrodes for supercapacitors

Symmetrical carbon/carbon double layer capacitors (EDLCs) were fabricated employing nanostructured mesoporous nongraphitized carbon black (NMCB) powders and their EDLC behavior was studied using electrochemical techniques viz., cyclic voltammetry, a.c.-impedance, and constant current cycling. Rectangular shape cyclic characteristics were observed indicating the double layer behavior of the NMCB carbon electrodes. The mechanism of double layer formation and frequency dependent capacitance were deduced from the ac-impedance analysis. Specific capacitance, power density and energy density were derived from constant current charge/discharge measurements. NMCB powders demonstrated a specific capacitance of about ∼39 F g−1 and the power density of 782 W kg−1 at a current density of 32 mA cm−2. Nevertheless, at a low current density (3 mA cm−2), the specific capacitance of ∼44 F g−1 was achieved, which corroborates with the values obtained by means of ac-impedance (40 F g−1) and cyclic voltammetry (41.5 F g−1). The test cells demonstrated the stable cycle performance over several hundreds of cycles

Non-commercial fish species in by-catch composition of shrimp trawl landing from Mahshahr creeks

Non-commercial fish species of shrimp trawls were studied monthly from October 2005 to September 2006 in Mahshahr creeks (Darvish, Doragh, Bihad, Ghazaleh, Ghanam, Zangi and Patil). The trawl nets had a cod-end mesh size of 24mm. Total catch was 6431 individuals weighing 55.5kg, and included 14 species of non-commercial fish species belonging to 14 families. The caught shrimp species were from Penaeidae; comprising only 30% of the total catches (4506 individuals weighting 44kg). Dominant species were Lieognathus hindus (54.8%), Metapenaeus affinis (18.2%) and Parapenaeopsis stylifera (9.8%). Maximum fish abundance was observed in March 2005 (98/3%) and for shrimp in June (66.2%). Bihad creek had the maximum percentage of fish (91.8%) by-catch and shrimp (42.9%) abundance. We conclude that the by-catch percentage of non-commercial fish is higher than shrimps in the study areas. Warm months witnessed the highest abundance of shrimp while January-March was the time period when by-catch was most abundant

The behavior of certain stochastic processes arising in window protocols

Window based network flow control protocols, such as TCP, modulate the number of unacknowledged packets the protocol is allowed to have outstanding. Such protocols change the size when they receive positive or negative acknowledgements, where the latter kind may be inferred from timeouts. Together with a communications channel that loses packets at random, such a protocol induces a stochastic process on the window size. We consider a broad class of window based protocols, and analyze various statistics of the induced stochastic process. We demonstrate that all these protocols can be treated analytically using the theory of semi-Markov processe

The behavior of stochastic processes arising in window protocols

Window based network flow control protocols, such as TCP, modulate the number of unacknowledged packets the protocol is allowed to have outstanding. Such protocols change the window size when they receive positive or negative acknowledgments, where the latter kind may be inferred from timeouts. Together with a communications channel that loses packets at random, such a protocol induces a stochastic process on the window size. For a broad class of window based protocols, the induced stochastic process can be analyzed using the theory of semi-Markov processe

Comparing the Effects of Active and Passive Intradialytic Pedaling Exercises on Dialysis Efficacy, Electrolytes, Hemoglobin, Hematocrit, Blood Pressure and Health-Related Quality of Life

Background: The effect of exercise during hemodialysis has been a controversial issue, however, there are just few studies about the effect of active exercise during hemodialysis. Objectives: This study aimed to compare the effects of passive and active intradialytic pedaling exercises on dialysis efficacy, electrolytes, hemoglobin, hematocrit, blood pressure and health-related quality of life in hemodialysis patients. Patients and Methods: This quasi-experimental study was conducted on 16 hemodialysis patients in Akhavan hemodialysis center in Kashan from April to November 2013. Active or passive intradialytic pedaling exercise was performed using a Mini-Bike for 30 minutes during the first two hours of the dialysis sessions. The quality of life (QOL) was assessed before and after the intervention. Blood pressure was examined at the beginning and then hourly during the dialysis sessions. Dialysis efficacy, levels of phosphorus, calcium, sodium, potassium and Blood urea nitrogen (BUN) were measured at the end of the intervention. Kolmogorov-Smirnov test, paired t test, Wilcoxon signed rank and Friedman tests and repeated measure analysis of variancewere used to analyze the data. Results: No significant changes were observed in serum potassium, phosphorus and calcium levels at the end of the passive exercise program compared to the baseline. However, phosphorus levels were significantly decreased in the active exercise program (P < 0.05). Moreover, the mean diastolic blood pressure was significantly decreased after the passive exercise (P = 0.039). Passive exercise did not significantly change the dialysis efficacy, urea reduction rate, hemoglobin and calcium levels. The mean overall QOL was 63.78 ± 21.15 at the beginning of the study, which was increased to 77.07 ± 21.14 at the end of eight weeks of the intradialytic exercise (P = 0.007). Conclusions: The passive intradialytic exercise had a positive effect on blood pressure. The active exercise could decrease the serum phosphorus and potassium levels. Moreover, both exercise programs could significantly improve the QOL. Both active and passive intradialytic exercises can have some beneficial effects