In this paper, we use concepts and results from percolation theory to investigate and characterize the effects of multi-channels on the connectivity of Dynamic Spectrum Access networks. In particular, we focus on the scenario where the secondary nodes have plenty of vacant channels to choose from-a phenomenon which we define as channel abundance. To cope with the existence of multi-channels, we use two types of rendezvous protocols: naive ones which do not guarantee a common channel and advanced ones which do. We show that, with more channel abundance, even with the use of either type of rendezvous protocol, it becomes difficult for two nodes to agree on a common channel, thereby potentially remaining invisible to each other. We model this invisibility as a Poisson thinning process and show that invisibility is even more pronounced with channel abundance. Following the disk graph model, we define and characterize connectivity of the secondary network in terms of the available number of channels, deployment densities, number of transceivers per node, and communication range. When primary users are absent, we derive the critical number of channels which maintains super-criticality of the secondary network. When primary users are present, we characterize and analyze the connectivity for all the regions: channel abundance, optimal, and channel deprivation. Our results can be used to decide on the goodness of any channel rendezvous algorithm by computing the expected resultant connectivity.
The current study aimed to examine the histomorphological features of the oral salivary ducts and the peacock tongue (Pavo cristatus) of this species. In this study, eight healthy adult peacocks were used after collecting them from a commercial market in Baghdad to investigate and describe the tongue in these bird species. After being euthanized, they were killed by cutting off the major neck blood vessels and bleeding until death; the tongue was identified. The tongue was the sharp end, elongated, somewhat triangular, and measured 8.2 mm. The apex, trunk, and base are its three sections. There are 4 to 5 layers of big conical papillae on the area where the root and body converge. Without gustatory papillae, the dense keratinized ep
... Show MoreBlogs have emerged as a powerful technology tool for English as a Foreign Language (EFL) classrooms. This literature review aims to provide an overview of the use of blogs as learning tools in EFL classrooms. The study examines the benefits and challenges of using blogs for language learning and the different types of blogs that can be used for language learning. It provides suggestions for teachers interested in using blogs as learning tools in their EFL classrooms. The findings suggest that blogs are a valuable and effective tool for language learning, particularly in promoting collaboration, communication, and motivation.
This research paper is about thevariationin the degree of Continentality climate of the
Iraq during (40) years for a number of climate station. Using Poresof formula, it is found out
that the climate of Iraq ranges between extreme Continentality and very extreme
Continentality, and that the Continentality degree is characterized with extreme frequency
from one year to another. In certain years, the degree of climate Continentality decreases
while in other years it rises in such a way that there is no similarity in the Continental degree
from one year to another for the same station.
As for the general trend of the degree of Continentality, the last years had noticed
special variations, which are divided in to thre
Form naming system Simiaúaa can not be studied in isolation from the dimensionality of social and psychological , no doubt that names carry data psyche during social interaction , deflagration volunteered her body signifier in formats that meet the margin emotional part of the signified , Vtngams forms functions in coordinated trading to function as semantic double , it operates on coding , as well as carry emotional charge .
The science of semiotics cares Pettmvsal indications and forms of circulation, and is made form the semantic patterns , and pattern of production , and methods of functioning . Stop quite a few specialists and critics and researchers at Dalia ignorant poet and knight known ( Duraid bin embolism Jashmi ) ; it rep
Forty different samples (water and soil) were collected from different places in Iraq and Syria. Only (6) isolates showed the ability to grow and utilize agar as a sole source of carbon and energy. Morphological, cultural characterization and biochemical tests confirmed that These isolates belonging to genus Pseudomonas (HK1-HK6) .Plasmid profiles results showed that these isolates were harbored (2 -3) small Plasmids . HK1 isolate was selected because of its efficiency and ability to grow in high density on agar media for transformation and curing experiments, these were checked by transformation experiments after their expression in E. coli MM294. The genes responsible for agar utilization were located on thes
... Show MoreAcromegaly is a rare disease produce generalize and serious alteration in the patient with active disease. Many of these patients are also diabetic. Many analytes, hormones, markers are change in these disease. The objective of study is to assess the modification in a number of parameters that changed during the acromegaly as a result of excess in GH and IGF1 levels. The study included 36 patients and 38 healthy controls, paired by sex and age and BMI. Serum concentration of GH and the other parameters including (insulin, glucose, lipid profile, uric acid ) were determined by biochemical method .Compared to controls, acromegalic patients had increased levels of GH, insulin, glucose, triglyceride, very low density lipoprotein(VLDL) (p<0.05)
... Show MoreBackground: Determination of sex and estimation of stature from the skeleton is vital to medicolegal investigations. Skull is composed of hard tissue and is the best preserved part of skeleton after death, hence, in many cases it is the only available part for forensic examination. Lateral cephalogram is ideal for the skull examination as it gives details of various anatomical points in a single radiograph. This study was undertaken to evaluate the accuracy of digital cephalometric system as quick, easy and reproducible supplement tool in sex determination in Iraqi samples in different age range using certain linear and angular craniofacial measurements in predicting sex. Materials and Method The sample consisted of 113of true lateral cepha
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