2,292 research outputs found
Cooperative Multi-Bitrate Video Caching and Transcoding in Multicarrier NOMA-Assisted Heterogeneous Virtualized MEC Networks
Cooperative video caching and transcoding in mobile edge computing (MEC)
networks is a new paradigm for future wireless networks, e.g., 5G and 5G
beyond, to reduce scarce and expensive backhaul resource usage by prefetching
video files within radio access networks (RANs). Integration of this technique
with other advent technologies, such as wireless network virtualization and
multicarrier non-orthogonal multiple access (MC-NOMA), provides more flexible
video delivery opportunities, which leads to enhancements both for the
network's revenue and for the end-users' service experience. In this regard, we
propose a two-phase RAF for a parallel cooperative joint multi-bitrate video
caching and transcoding in heterogeneous virtualized MEC networks. In the cache
placement phase, we propose novel proactive delivery-aware cache placement
strategies (DACPSs) by jointly allocating physical and radio resources based on
network stochastic information to exploit flexible delivery opportunities.
Then, for the delivery phase, we propose a delivery policy based on the user
requests and network channel conditions. The optimization problems
corresponding to both phases aim to maximize the total revenue of network
slices, i.e., virtual networks. Both problems are non-convex and suffer from
high-computational complexities. For each phase, we show how the problem can be
solved efficiently. We also propose a low-complexity RAF in which the
complexity of the delivery algorithm is significantly reduced. A Delivery-aware
cache refreshment strategy (DACRS) in the delivery phase is also proposed to
tackle the dynamically changes of network stochastic information. Extensive
numerical assessments demonstrate a performance improvement of up to 30% for
our proposed DACPSs and DACRS over traditional approaches.Comment: 53 pages, 24 figure
Karyology of Abramis brama in the southern waters of Caspian sea
The karyology of bream (Abramis brama) were done for the first time in Iran. This study was conducted on chromosomal number, chromosome arms and karyotyping of bream from the -Southern part of the Caspian Sea with preparing chromosomal extensions on the base of Squash method. The number of metaphase plates using Squash method on renal and gill tissues was determined as to be 2n=50 and the number of chromosome arms was NF=82. The prepared karyotype of this species was consisted of 8 pairs of metacentric, 8 pairs of submetacentric and 9 pairs of acrocentric chromosomes
Gene 18s rRNA variation of cuttlefish population (Sepia pharaonis) in the Persian Gulf and the Oman Sea using PCR-RFLP method
We used PCR-RFLP method to identify cuttlefish (Sepia pharaonis) populations in the Persian Gulf and the Sea of Oman. Bottom trawling method was used to collect a range of 20 to 40 specimens from each 15 stations in the study area. Genomic DNA was extracted by phenol-chloroform method and one pair primer was designed for the analysis based on 1 Ss rRNA gene nucleotide sequences. A PCR product with 502 pair bases in length was obtained for all specimens and subjected to digestion by eight restriction enzymes Alui, Tacit, MO, Rsal, Hinalli, Dral, Prull and Mien DNA banding, patterns in all specimens were similar and no polymorphism was detected among them. We conclude that cuttlefish populations cannot be isolated using 18s rRNA gene extracts in the area of study
Population structure of Acipenser nudiventris in the south coast of Caspian Sea and Ural River using microsatellite method
Population structure of Ship sturgeon, Acipenser nudiventris, from the south coast of Caspian Sea and Ural River was investigated using Microsatellite method. For this reason, 73 specimens of the sturgeon were collected from five locations in two sampling regions the first consisted of Bandar Anzali, SefidRud River, Babolsar, and Gorgan, and the second was Ural River. Four SSR markers were used in this investigation, of which 5 loci produced DNA band, with three of them being polymorph. One primer showed two loci with one of them being polymorph and another was monomorphic). Average expected and observed heterozygosity was 0.86 and 0.75 respectively. Genetic variation was assessed through analysis of molecular variance (AMOVA) that indicated almost all of the variance in data namely %94 (P less than or equal to 0.03) was within locations
Introducing genetic markers to identify and distinguish five species of Cyprinidae in the Caspian Sea using PCR-RFLP
Cyprinids are the main and most significant bony fishes found in the Caspian Sea. In this study, 15 specimens of Rutilus fish kutum (Kamensky, 1901), 10 specimens of Barbus capito (Gueldenstaedtii, 1772), 10 specimens of Bream Abramis brama (Linnaeus, 1785), 10 specimens of Redlip, Aspius aspius, and 15 specimens of Kora volba, Rutilus rutilus caspius, were collected from commercial catch stations. DNA from all specimens was extracted using the phenol-chloroform method in 500[1.1 tubes and amplified using PCR method with a pair of primers with cytochrom b gene sequence of Kora volba. For RFLP analysis, PCR products of cytochorome gene b (1117 bp) from each species were digested with five restriction enzymes under suitable conditions of incubation. DNA bands were visualized by gel electrophoresis (polyacrylamide) and staining with silver nitrate. Five enzyme Rsa I, Hinf I. Hha I , Hine II, and Mbo I showed polymorphism. Genotypes obtained from digestion of enzymes Rsa I, Hinf I, Hha I showed haplotypes AAAAA for Barbus capito, BBBB for R. rutilus caspius, CCCC for Bream Abramis brama, DDDD for Aspius aspius and EEEE for R. frisii kutum. Each of these haplotypes serves as a genetic marker for the species and is of significant importance in distinguishing them
Effect of travelling fire on structural response of a generic steel fire protected moment resisting frame
To simulate a fire inside large compartments, there is a pioneering method called ‘traveling fire’. As steel structures are vulnerable to high temperatures, they are normally fireproofed by insulation materials appropriate for a specific duration of time. An investigation is performed here to examine the robustness of a generic fourstory moment-resisting steel structure, fireproofed to comply with the one-hour standard curve, when it is subjected to traveling fire. The results show that while no collapse occurs during the 12.5%, 50% and 100%, the structure collapses under the 25% fire size at 75 min. This seems to be in contradiction with traditional belief, where it is assumed that taking into consideration a larger-scale fire in a compartment would increase the safety margin. The investigation performed also underlines that the fireproofing of structures does not necessarily provide adequate resistance under traveling fires
Using RAPD markers potential to identify heritability for growth in Fenneropenaeus indicus
Sampling was done using 90 post larvae which were produced by reproduction of some broodstocks of Fenneropenaeus indicus in one day and reared in the same situation for 4 months. Samples were divided into 3 groups: high, medium and low growth (based on weight and length). Genomic DNA was extracted from muscle tissue using the phenol-chloroform method. The polymerase chain reaction (PCR) was carried out using 21 RAPD loci and PCR products were separated on 3% Agarose gel. From 21 loci studied, 12 produced polymorphic bands. The most polymorphic produced bands using OPAQ 9 and the least by OPAQ 7. Search for specific markers in F. indicus one specific band was observed in the low growth group using OPAQ4. The highest genetic distance (0.457) was between the low growth group and the medium and the lowest (0.091) between high growth and medium groups, therefore the highest genetic identity (0.912) was between high growth and medium groups and the lowest (0.633) between low growth group and the medium. Neighbor-joining resulted in two groups, the first including high and medium growth groups and the second low growth group. It appears that low growth group depended on separated population. Considering the mean weight of F1 (mean weight of 90 specimens) (16.25±1.5 g), parental generation mean weight of 15 ±1.2 and mean weight of parent 31.6 g, response to selection (R) and heritability for growth in this species were estimated to be 1.2±0.2 and 0.07±0.01 respectively
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