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Multi-Channel Distributed DSA Networks: Connectivity and Rendezvous Tradeoffs
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In this paper, we investigate and characterize the effects of multi-channel and rendezvous protocols on the connectivity of dynamic spectrum access networks using percolation theory. 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-channel, 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 protocols, 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 represent the multiple channels as parallel edges in a graph and build a multi-layered graph (MLG) in R2. In order to study the connectivity, we show how percolation occurs in the MLG by coupling it with a typical discrete percolation. Using a Boolean model and the MLG, we study both cases of primaries' absence and presence. For both cases, we define and characterize connectivity of the secondary network in terms of the available number of channels, deployment densities, number of simultaneous transmissions per node, and communication range. When primary users are absent, we derive the critical number of channels which maintains supercriticality 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. For each region we show the requirement and the outcome of using either type of rendezvous techniques. Moreover, we find the tradeoff between deployment-density versus rendezvous probability which results in a connected network. Our results can be used to decide on the goodness of any channel rendezvous algorithm by computing the expected resultant connectivity. They also provide a guideline for achieving connectivity using minimal resources.

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Publication Date
Mon Dec 30 2013
Journal Name
Journal Of The College Of Basic Education
Synthesis and Antimicrobial Activities of (Mn, Co, Ni, Cu, Hg and Ag) Complexes with Poly (Vinyl-4-Aminobenzoate)
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The aim of this work is synthesis of _Eoly (Vinyl-4-AminoBenzoate) (PVAB) from reaction of _Eoly Vinyl Alkohol PVA with 4-aminobenzoyl chloride in alkaline media. We also prepare the metal complexes of poly (vinyl- 4-aminobenzoate) and antimicrobial properties were evaluated by dilute method against five pathogenic bacteria (Escherichia coli, Shigella dysentery, Klebsiella pneumonae, Staphylococcus aureus, Staphylococcus Albus) and two fungal (Aspergillus Niger, Yeast). All polymer metal complexes showed different activities against the various microbial isolates. The polymer metal complexes showed higher activity than the free polymer.

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Publication Date
Sun Jun 12 2011
Journal Name
Baghdad Science Journal
Analysis of grape fruits and grape seed for their major , minor and trace elemental contact by XRF technique
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Grapes and grape seeds are important samples employed for environmental medical studies . The air of this work was to identify and concentration calculation of the elements in grapes fruit and thier seeds by using X-Ray fluoresces technique (XRF) . Samples were collected from Abo Ghraib of Baghdad city ,the grape seeds were obtained from those samples . Both samples were taken under experimental procedure to obtain the sample which were ready for analysis . The samples were then submitted to experimental conditions using a radiation source and then samples were applied for counting analysis shows the elements Na , Mg , Al , Si , P , S , Cl , K , Ca , and Sr as major components of the samples. Fe , Sr , I , Ba and V were

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Publication Date
Sun Mar 05 2017
Journal Name
Baghdad Science Journal
Detection of wheat damping off and root rot disease pathogenic fungi and it bio control by pseudomonas fluorescens
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This study was conducted to determine the fungal cause and bio control of damping off and root rot of wheat plants by using pseudomonas fluorescens under greenhouse and field conditions. Results showed isolation of eight species from the soil and roots to deferent region of Baghdad government. Rhizoctonia solani (Rs) and Fusarium solani (Fs) were the predominant damping off fungus with frequency 60 and 52% respectively. Led the using of bacteria formulations such as crud suspension , pure bacteria filtration and pure living cells in culture medium inhibit all type fungi with rates ranging from 84-96% , 80- 93% and 75-88% respectively. Rs and Fs were more pathogenesis under greenhouse conditions, with incidence of 80 and 68% and disease s

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Publication Date
Fri Dec 15 2023
Journal Name
Al-academy
The extent of theatrical and musical arts contribute to the diagnosis And treatment of psychological problems Inmates of
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 The research aims to identify the extent to which the theatrical and musical arts contribute to diagnosing and treating psychological problems among the residents of children’s villages in Jordan, and the methodologies adopted by the theatrical and musical arts to achieve this. It moves on to prove the theory that theatrical and musical arts have an impact on improving the psychology of the residents of children’s villages in Jordan by reviewing the theories and opinions that address the subject from a scientific point of view proven by experiences and expertise. The research took place in the period between (2019-2020), and the spatial limits came within the (SOS) children's villages in Jordan. The importance of the research is to

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Publication Date
Thu Dec 01 2016
Journal Name
Iraqi Journal Of Science
Callus Induction and Proliferation as Affected by EMS and UV-B Mutagens in Rice (Oryza sativa L.) Genotypes
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Seeds of the two rice genotypes namely Amber 33 (A33) and Amber Baghdad (AB) were divided into two groups; the first was presoaked in different concentrations of ethyl methane sulphonate (EMS) as chemical mutagen for different duration times (3, 6 and 12) hrs, and the other was exposed to different exposure times of ultra violate (UV-B) radiation (280-320 nm) as physical mutagen for different times (20, 40 and 60) min at room temperature. Treated and non-treated seeds were transferred into the callus induction medium containing 2.5 mg/L 2,4- dichlorophenoxy acetic acid (2,4-D) and 0.5 mg/L benzyl adenine (BA) under aseptic conditions. Calli were divided into two groups the first was treated with several EMS concentrations (0.0, 0.50. 1.0, 1

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Publication Date
Mon Mar 13 2017
Journal Name
Journal Of Baghdad College Of Dentistry
Dental Caries Experience and Salivary Elements Among A Group of Young Adults In Relation to Age and Gender
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ABSTRACT Background: Dental caries is a most common social and intractable infectious disease in human. Saliva is critical for preserving and maintaining oral health and salivary elements had many effects on caries experience. Aim of study: This study was conducted to assess dental caries severity by age and gender and their relation to salivary zinc and copper among a group of adults aged (19-22) years. Materials and methods: After examination eighty persons aged 19-22 years of both gender. Caries severity was documented according to DMFS index. Stimulated salivary samples were collected and chemically analyzed under standardized condition to detect salivary elements zinc and copper. Concentrations of Zinc and copper were measured by using

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Publication Date
Mon Jun 01 2015
Journal Name
Journal Of Economics And Administrative Sciences
Display, analyze and evaluate the alternatives selected models used in the measurement and disclosure of corporate social responsibility
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       The economic development and intense competition may make economic units neglected the social aspect as a service workers and the environment, the community and focus on the economic side and achieve profitability only, which puts it in a position of accountability of trade unions and bodies, environment, health, civil society organizations and the focus of many studies accounting in order to clarify social activities and disclosed in the financial statements, increasing pressure from multiple parties calling for governments to issue laws and regulations oblige economic units to disclose complete and accurate information in a timely manner for all social activities and be subj

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Publication Date
Mon Jun 10 2024
Journal Name
Humanities And Social Sciences Communications
The mediating role of accounting information systems in small and medium enterprise strategies and organizational performance in Iraq
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Abstract<p>This paper examined accounting information systems (AIS) as a mediator between small and medium-sized enterprises (SMEs) strategies, including (finance source, administrative innovation, organizational culture, developing capabilities levels of SMEs, information source, development of business managers, and technological innovation) and organizational performance. In this quantitative study, 450 self-administered questionnaires were distributed to the managers and owners of SMEs using purposive sampling. Data were analyzed using the structural equation modeling (SEM) method via SmartPLS3 Software. The study offers empirical findings on the importance of AIS as a mediator, considers various factors, a</p> ... Show More
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Publication Date
Fri Nov 03 2023
Journal Name
Karbala International Journal Of Modern Science
Synthesis and characterization of zirconium oxide nanoparticles using Z. officinale and S. aromaticum plant extracts for antibacterial application
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Publication Date
Tue May 17 2016
Journal Name
Iosr Journal Of Nursing A Nd Health Science (iosr-jnhs)
Comparative Study of Abnormal Renal Function Tests and Liverfunction Tests in Type1 and Type2 Diabetes Mellitus in Iraq
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This study was planned to evaluate the renal function tests and liver function tests and it carried out in Al-Yarmouk hospital,Baghdad –Iraqin patients withtype 1 and type 2 diabetes mellitus by measuring(uric acid,urea and creatinine) ,Aspartate aminotransferase (AST) and Alanine aminotransferase (ALT). Seventy five individuals of Iraqi adults (male) were divided into three groups, 25 patients with type1 diabetes mellitus ,25 patients with type 2 diabetes mellitus and 25 normal individuals were taken as control group. The mean value of uric acid, urea and creatinine was higher significantly in patients thanin control group (P< 0.05),while the correlation(p< 0.01) between age ,creatinine in type 1 and between age and (Urea, Uric acid ,cr

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