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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
Thu Jun 29 2023
Journal Name
Wasit Journal For Pure Sciences
Association between Anthropometric Measurements and some Biochemical Parameters in Premenopausal and Postmenopausal Women
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Numerous physiological and biochemical changes are linked to menopause. The current study was intended to examine the transforms linked to anthropometric measurements and bone-related factors. In this study of 80 women which included; they comprised 40 premenopausal women and 40 postmenopausal women. waist circumference (WC), body mass index (BMI), hip circumference (HC), moreover waist to hip ratio are among the anthropometric measurements (W-HR) recorded by standard procedures. The plasma samples were tested for the following biochemical parameters: bone-related parameters [calcium (Ca), phosphorus (P), uric acid (UA), alkaline phosphatase (ALP), and erythrocyte sedimentation rate (ESR)] and serological agglutination tests [rheumat

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Publication Date
Wed Dec 20 2023
Journal Name
Discourse And Interaction
Refusal and politeness strategies favoured among Iraqi and Malaysian learners in marriage proposals
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The study targets exploring the similarities and differences between Iraqi and Malaysian learners of English in refusing marriage proposals. Also, it examines the favored politeness strategies that learners use to protect their interlocutors’ face, heeding both their social distance and status. Data were gathered by a Discourse Completion Task (DCT) which contained six marriage situations. Responses were analyzed based on Beebe et al.’s (1990) refusal taxonomy and Scollon et al.’s (2012) politeness system. The findings indicated that both the Iraqi and Malaysian learners preferred the indirect refusal strategies in marriage proposals, as well as the hierarchical politeness in the form of independence strategies regardless of t

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Publication Date
Wed Jan 07 2015
Journal Name
World Journal Of Experimentalbiosciences
Biofilm formation and antibiotic susceptibility for clinical and environmental isolates of Pseudomonas aeruginosa
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Pseudomonas aeruginosa is emerging opportunistic clinical pathogens. Clinical isolates of P. aeruginosaresist wide spectrum of antibiotics and form biofilm. The comparison study between clinical and environmental of P. aeruginosa in terms of biofilm formation and antibiotic resistance is very scanty. Thus, in current study microtiter plate technique was used to measure the biofilm formation by several clinical and environmental isolates. Moreover, the antibiotic susceptibility of these bacteria was evaluated by VITIK 2 techniques. The relationship between the antibiotic susceptibility and biofilm formation was evaluated for clinical and environmental isolates. Clinical and environm

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Publication Date
Mon Nov 06 2023
Journal Name
Al- Ustath Journal
INFINITIVAL AND GERUNDIAL CONSTRUCTIONS OF ASPECTUAL VERBS IN SELECTED BRITISH AND AMERICAN NOVELS
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Abstract Infinitives and gerunds are non-finite verb forms which cannot be indicated by tense, number, or person. The construction of non-finite verbs is intricate because of their nature of meanings, forms, and functions. The major problem is that both infinitival and gerundial complements have identical functions and occupy identical positions in the sentences. Thus, there is a confusion in using an infinitival and gerundial forms after aspectual verbs. The selection of either one of these two forms as complements is controlled syntactically or semantically. Moreover, both forms can be used usually with similar predicate but with neat difference in meaning. In addition, there are problems with controlling the use of aspect, since aspectua

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Publication Date
Sun Feb 03 2019
Journal Name
Journal Of The College Of Education For Women
Emotional deprivation and its relation with the behavioral and nervous problems for adolescents
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Publication Date
Fri Mar 31 2017
Journal Name
Iraqi Journal Of Pharmaceutical Sciences ( P-issn 1683 - 3597 E-issn 2521 - 3512)
ROLE OF SERUM ZINC AND COPPER AND ZINC/ COPPER RATIO IN ALOPECIA AREATA
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Alopecia areata is considered as a major health problem, its importance is attributed to its
recent increased incidence in our population. Till now, there is no exact cause for alopecia areata
although researchers thought it's an autoimmune disease.
This clinical study was designed to evaluate the role of trace elements (zinc and copper) in patients
with alopecia areata. Twenty patients were diagnosed as having alopecia areata with an age range
(10-40 years) were involved in this study. Normal subjects of the same age group were also
evaluated as control. The level of serum Zn and Cu were measured by flame atomic absorption
spectrophotometry in both control and patient group. And the ratio of Zn/Cu was also estimated

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Publication Date
Mon Jul 06 2020
Journal Name
International Journal Of Research In Pharmaceutical Sciences
Obesity and Breast Cancer: Circulating Adipokines and Their Potential Diagnostic as Risk Biomarkers
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Obesity and cancer are two major epidemics of this century. Obesity is related to a higher risk of many types of cancer. Studies have accessed circulating adipokines, as key-mediators in obesity and breast cancer. The study is aimed to examine the circulating levels of insulin-like growth factor-1, leptin, adiponectin, and resistin in premenopausal Iraqi women with breast cancer. The current study was performed during the period from June 2019 to December 2019 at Oncology unit/ Medical City Hospital-Baghdad. A total of 90 premenopausal women with BC/ stage II and III after 2nd dose of chemotherapy were contributed in this study as patients group. Their ages ranged from (35- 50) years in addition to 90 premenopausal healthy women wer

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Publication Date
Sun Jan 03 2016
Journal Name
Journal Of The College Of Basic Education
Simultaneous determination of cephalexin and cefixime by first and second derivative ultraviolet spectrophotometry
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Publication Date
Wed Sep 30 2015
Journal Name
College Of Islamic Sciences
Imam Muslim bin Qasim al-Qurtubi   And his efforts in wound and modification
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Imam Muslim bin Qasim al-Qurtubi   And his efforts in wound and modification

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Publication Date
Tue Dec 30 2008
Journal Name
Al-kindy College Medical Journal
Knowledge, Beliefs and Attitudes towards AIDS among Intermediate and Secondary School Teachers; Baghdad
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Back ground: AIDS is considered a dreaded disease.
According to recent estimates, 42 million people suffer
from HIV/AIDS (90% of these being in the developing
countries), with 5 million people newly infected with HIV
and 3.1 million deaths in the year 2002 globally. At
present, there is no effective vaccine to prevent the
disease. Hence, Health education (Information, Education
and Communication) activities bringing about behavioral
changes in the community, promoting healthy sexual
behavior and preventing the risky ones is the best possible
solution to the problem of AIDS.
Objectives: To find out the knowledge, beliefs and
attitudes regarding various aspects of HIV/AIDS amongst
intermediate and sec

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