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Connectivity and rendezvous in distributed DSA networks
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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.

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Publication Date
Wed May 01 1985
Journal Name
International Journal Of Mass Spectrometry And Ion Processes
Energy distributions of atmospheric ions drifting in rare gases
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Publication Date
Mon Aug 30 2021
Journal Name
Al-kindy College Medical Journal
Spontaneous Coronary Artery Dissection in Multiple Gestation Peripartum Period
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Background: Non-atherosclerotic spontaneous coronary artery dissection (SCAD) is defined as a non-traumatic and non-iatrogenic separation of the coronary arterial wall. SCAD is a highly uncommon cause of myocardial infarction (0.1 to 0.4 %).

Case presentation: 40-year-old African American woman, G1T1P0A0L2, with a past medical history of tobacco abuse and obesity who had uncomplicated cesarean section delivery for healthy twins two weeks prior presented with substernal, sudden onset chest pain. The pain radiated to left arm and back, pressure-like, and is associated with nausea, vomiting, and dyspnea.

On examination she was within normal limits except for a well-healed C-section wound. An electrocardiogr

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Publication Date
Mon Jul 20 2020
Journal Name
Ibn Al-haitham Journal For Pure And Applied Sciences
Anatomical features of Fraxinus ornus L. growing in Iraq
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Fraxinus ornus L. is considered as a special species that is frequently planted as a decorative tree in most of the country. The cross-sections of the root and stem are circular in shape and in the secondary growth stage, the vascular tissue in the root and stem consists of secondary xylem in radial rows and the type of vessels in the xylem are ring pours wood. Epidermal cells of leaves undulate on the upper and lower side, hairs are uniseriate and unicellular and the stomata appeared in the abaxial surface only is anomocytic type. The vertical-section of blade leaf includes upper epidermis and lower epidermis followed by the palisade layer and spongy layers. The cross-section of petiole horseshoe shape and the vascular bundles are cover

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Publication Date
Sun Nov 01 2015
Journal Name
Journal Of Engineering
The Constituents of Active Structure in Contemporary Architectural Products
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The structure is considered in its scientific formula one of the concepts which complete the architectural image that seeks to take out an effective and attractive structure in contemporary architectural production, especially that the structure -in general- represents strength in addition to delight and functional benefits according to Vitruvius trinity. So, the role of structure depends on making its aesthetical properties able to give efficiency within architectural product. That has come through adoption of intellectual mechanism of structural means and details –as a whole or parts- and focused on structure with the recipient's needs, aesthetical, and sensory purposes in addition to its fundamental role of stabilit

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Publication Date
Tue Nov 30 2021
Journal Name
Research Journal Of Pharmacy And Technology
Effect of Palliative Radiotherapy in controlling pain of Malignancy
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Background: Radiation therapy reported to be an effective in palliating pain. Objective: To describe roles of palliative radiotherapy in controlling pain in metastatic cancerous patients, and evaluation of radio-therapy doses in pain management. Methods: A prospective observational study carried out at the Baghdad Radiotherapy and Nuclear Medicine Center/Baghdad Medical City Complex, Baghdad, Iraq, from 1st of December 2018 to 30th of May 2019. 88 Patients, were included. Patients were assessed before applying radiotherapy, and at the end of treatment. Pain scoring used from 0 to 10. Kaplan Meier survival curve used. Result: The mean±SD of age was 55.44±11.1 years, and the most frequent age group was 41-50years as 37(42.1%). Breas

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Publication Date
Sat Dec 11 2021
Journal Name
Engineering, Technology & Applied Science Research
The Influence of Base Layer Thickness in Flexible Pavements
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Flexible pavement design and analysis were carried out in the past with semi-experimental methods, using elastic characteristics of pavement layers. Due to the complex interferences between various layers and their time consumption, the traditional pavement analysis, and design methods were replaced with fast and powerful methods including the Finite Element Method (FEM) and the Discrete Element Method (DEM). FEM requires less computational power and is more appropriate for continuous environments. In this study, flexible pavement consisting of 5 layers (surface, binder, base, subbase, and subgrade) had been analyzed using FEM. The ABAQUS (6.14-2) software had been utilized to investigate the influence of the base layer depth on ver

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Publication Date
Thu Oct 12 2023
Journal Name
Mustansiriyah Journal Of Pure And Applied Sciences
Cavitation microbubbles in the medical ultrasound imaging: A Review
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Ultrasound is a mechanical energy which can generate altering zones of compression and rarefaction along its path in the tissues. Ultrasound imaging can provide a real time screening for blood and multiple organs to aiding the diagnostic and treatment. However, ultrasound has the potential to deposit energy in the blood and tissues causing bio effects which is depending on ultrasound characteristics that including frequency and the amount of intensity. These bio effects include either a stable cavitation presented non thermal effects or inertial cavitation of harmful effect on the tissues. The non-thermal cavitation can add features in diagnostic imaging and treatment more than the inertial cavitation. Ultrasound Contrast agents are a micro

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Publication Date
Sun Dec 15 2019
Journal Name
Journal Of Baghdad College Of Dentistry
Angiopoietin-2 Immunohistochemical Expression in Oral Squamous cell Carcinoma
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Background: There are various secreted proteins affecting the prognosis of oral squamous cell carcinoma (OSCC) and one of them is Angiopoietin-2(Ang-2) which is thought to have an essential role in the development and progression of the tumor. Aim of the study: This study was conducted to determine the expression of (Ang-2) in (OSCC) to assess its correlations with clinicopathological parameters of the tumor. Material and Methods: 36 formalin- fixed, paraffin- embedded tissue blocks histologically diagnosed as OSCC were examined for Ang-2 immunohistochemical expression semi quantitively. Results: The expression of Ang-2 was significantly associated with histopathological grade (P value=0.023), while there is no significant association wi

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Publication Date
Wed Jan 01 2014
Journal Name
Journal Of The College Of Languages (jcl)
Tennessee Williams: Memories as symbols in The Glass Menagerie
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The Glass Manegerie is a metaphor, which is one of the greatest plays  of great writer Williams. The play talks about  the poor people in society and how try to escape this group of people from the real world to get rid of the hardness of this tuff reality and live in a fantasy world that is much like the glass where the world is very weak this world is acting by Laura, she is  owner of these animals breakable glass where it's weak and unable to defend itself as well as the mother Amanda  is a very selfish never think about her children but only herself.

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Publication Date
Thu Apr 21 2016
Journal Name
Iraqi Dental Journal
Amoxicillin vs Levofloxacin in Treatment of Chronic Periodontitis: Review
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