Proximity Of Nodes Research Articles

A robust and non-singular formulation of the boundary integral method for the potential problem

A non-singular formulation of the boundary integral method (BIM) is presented for the Laplace equation whereby the well-known singularities that arise from the fundamental solution are eliminated analytically. A key advantage of this approach is that numerical errors that arise due to the proximity of nodes located on osculating boundaries are suppressed. This is particularly relevant in multi-scale problems where high accuracy is required without undue increase in computational cost when the spacing between boundaries become much smaller than their characteristic dimensions. The elimination of the singularities means that standard quadrature can be used to evaluate the surface integrals and this results in about 60% savings in coding effort. The new formulation also affords a numerically robust way to calculate the potential close to the boundaries. Detailed implementations of this approach are illustrated with problems involving osculating boundaries, 2D domains with corners and a wave drag problem in a 3D semi-infinite domain. The explicit formulation of problems with axial symmetry is also given.

Cascading failures in networks with proximate dependent nodes.

We study the mutual percolation of a system composed of two interdependent random regular networks. We introduce a notion of distance to explore the effects of the proximity of interdependent nodes on the cascade of failures after an initial attack. We find a nontrivial relation between the nature of the transition through which the networks disintegrate and the parameters of the system, which are the degree of the nodes and the maximum distance between interdependent nodes. We explain this relation by solving the problem analytically for the relevant set of cases. In the process, we solve a variant of Rényi's parking problem on treelike graphs.

Stochasticity and noise-induced transition of genetic toggle switch

The ability to predict and analyze the function of genetic circuits will enhance the design of autonomous, programmable, complex regulatory genetic structures. An abundance of modeling techniques has recently been developed to delineate simple genetic structures in terms of their constituents. Simple systems with characteristics of feedback inhibition, multi-stability, switching, and oscillatory expression have often been the focus. The present work is an attempt to improve existing deterministic models that fail to oblige to the crucial aspect of noise in genetic modeling. The objective of this work is to analyze, model, and simulate the protein populations in gene expression mechanisms by resorting to stochastic algorithms. The system involves two types of genes; the protein produced from the expression of one gene is capable of turning off the expression of the other gene. Rates of degradation of these proteins are assumed to be proportional to their concentrations. The master equation of this ‘genetic toggle switch’ is formulated using the probabilistic population balance around a particular state and by considering five mutually exclusive events. The efficacy of the present methodology is mainly attributable to the ability to derive the governing equations for the means, variances, and covariance of the random variables by the method of system-size expansion of the nonlinear master Equation. A less laborious approach based on Kurtz’s limit theorems for the derivation of the stochastic characteristics is also presented for comparison. Solving the resultant ordinary differential equations governing the means, variances, and covariance of the master equations simultaneously using the published data yield information concerning not only the means of the two populations of proteins but also the minimal uncertainties of the populations inherent in the expressions. It is demonstrated that systems with small populations are susceptible to large internal fluctuations (or uncertainties) in their population evolution. Large uncertainties are observed after the populations enter the proximity of the saddle node, which is likely to cause transition of system’s steady state from one to another. Independent Monte-Carlo simulation runs clearly demonstrates that the occurrence of such internal noise-induced transition.

How to Build an Alternative to Sprawl and Auto-centric Development Model through a TOD Scenario for the North-Pas-de-Calais Region? Lessons from an Integrated Transportation-land Use Modelling

This paper discusses results of an integrated land use and transport modelling, carried out for the territory of the French region of North-Pas-de-Calais using the software Tranus. The interest of this research was to simulate, test and evaluate impacts of a Transit Oriented Development regional plan, using the LUTI modelling tool. Therefore were analyzed evolution of transport demand modal share and dynamics of real estate market and of localization choices of population and activities. TOD is a model of urban development that promotes high quality, mixed and multi-functional densification, located in proximity of transit nodes and corridors, with priority to non-motorized mobility and with the aim to reduce land consumption and car dependency. Multiple TOD examples can be found at urban and metropolitan scale, with different characteristics depending on the socio-economic and territorial contexts, while rarer are interventions at a regional scale. Therefore this research aim to analyze the application of a TOD regional plan, applied to a specific group of regional railway nodes and corridors, selected for their TOD potential. Results showed that some rail corridors initially selected, clearly confirmed their TOD potential and that TOD effects are more evident in areas with good basic levels of attractiveness and of economic dynamism. Furthermore, if policy of densification clearly contributes to concentrate residential demand in urban zones and to limit urban sprawl, further incentives has to be organized in favor of transit use. More interesting effects are in fact found by simulating transit integrated tariff policies between regional train and bus services, as well as interventions discouraging car use, in addiction to TOD urban configurations.

Improved Proximity Aware Load Balancing for Heterogeneous Nodes

load balancing schemes are efficient at increasing the utilization of CPU, memory, and disk I/O resources in a Distributed environment. Most of the existing load-balancing schemes ignore network proximity and heterogeneity of nodes. Those schemes follow the technique of self owned resource based load balancing. But load balancing involves more challenges due to lack of sources for some of the tasks. Hence it is not always possible the task get all required resources on a single node. Consider node conditions i. e. the other nodes situated in its context. The task which lack with some of the resources will try to negotiate those resources with these contextual nodes. Then a task can complete and the resources utilized will be released. Doing this we are able to reduce load migrations. This proposed scheme not only works well with heterogeneous nodes but also considers proximity in them. Our result shows more than 20% reduction in communication costs than the previous methods based on self-owned resource distribution of nodes. Keywordssystem, context based load balancing, and proximity aware load balancing.

Neighborhood randomization for link privacy in social network analysis

Social network analysis has many important applications but it depends on sharing and publishing the underlying graph. Link privacy requires limiting the ability of an adversary to infer the presence of a sensitive link between two individuals in the published social network graph. A standard technique for achieving link privacy is to probabilistically randomize a link over the space for node pairs. A major drawback of such graph-wise randomization is that it ignores the structural proximity of nodes, thus, alters considerably the structure of social networks and distorts the accuracy of social network analysis. To address this problem, we propose a structure-aware randomization scheme, called neighborhood randomization. This scheme models a social network as a directed graph and probabilistically randomizes the destination of a link within a local neighborhood. By confining the randomization to a local neighborhood, this scheme drastically reduces the distortion to the graph structure yet hides a sensitive link. The trade-off between privacy and utility is dictated by the retention probability of a destination and by the size of the randomization neighborhood. We conduct extensive experiments to evaluate this trade-off using real life social network data.

From biological to social networks: Link prediction based on multi-way spectral clustering

Link prediction in protein–protein interaction networks (PPINs) is an important task in biology, since the vast majority of biological functions involve such protein interactions. Link prediction is also important for online social networks (OSNs), which provide predictions about who is a friend of whom. Many link prediction methods for PPINs/OSNs are local-based and do not exploit all network structure, which limits prediction accuracy. On the other hand, there are global approaches to detect the overall path structure in a network, being computationally prohibitive for huge-size PPINs/OSNs. In this paper, we enhance a previously proposed multi-way spectral clustering method by introducing new ways to capture node proximity in both PPINs/OSNs. Our new enhanced method uses information obtained from the top few eigenvectors of the normalized Laplacian matrix. As a result, it produces a less noisy matrix, which is smaller and more compact than the original one. In this way, we are able to provide faster and more accurate link predictions. Moreover, our new spectral clustering model is based on the well-known Bray–Curtis coefficient to measure proximity between two nodes. Compared to traditional clustering algorithms, such as k-means and DBSCAN, which assume globular (convex) regions in Euclidean space, our approach is more flexible in capturing the non-connected components of a social graph and a wider range of cluster geometries. We perform an extensive experimental comparison of the proposed method against existing link prediction algorithms and k-means algorithm, using two synthetic data sets, three real social networks and three real human protein data sets. Our experimental results show that our SpectralLink algorithm outperforms the local approaches, the k-means algorithm and another spectral clustering method in terms of effectiveness, whereas it is more efficient than the global approaches.

NEED OF EPICARDIAL INSTRUMENTATION TO OPTIMIZE THE ABLATION SITE FOR SINUS NODE MODIFICATION

Catheter ablation of inappropriate sinus tachycardia (IST) is a challenging procedure due to the proximity of the sinus node to the phrenic nerve, and the predominant epicardial location of the sinus node structure. We report a consecutive series of patients undergoing ablation of IST and

Multi Hop Secure Adhoc Network to Eradicate Cooperative Diversity

The concept of peer to peer mobile networks reflects on tactical network. This approach helps mobile nodes to scatter anywhere in the network and it also provide additional support for the MANET in terms of data distribution. This paper provides the result of such approach in terms of network cluster formation with secure node proximity within the boundary. This proximity paradigm will enhance the performance of network by avoid wide scattering of mobile nodes beyond the networks zone. The results shown in this paper were the work done in ns2 mobility package. The result also incorporates AODV routing protocol with IEEE 802.11 MAC for wireless network to improve network performance using mobile node proximity in conjunction with the previous work indicating the network performance degradation with these configuration. To device proximity among mobile nodes were done along with secure mechanism, such that every nodes data transmission was done only on the basis of IDS implementation with PSO fitness value. This will invoke security for every data transmission done on this network. This work has significant effect by improving network performance by 50%. Keywords: Multi Hop Cellular Network, Mobile Node Proximity, Tactical Mobile Network

A Targeted Approach to Sentinel Lymph Node Biopsies in the Parotid Region for Head and Neck Melanomas

Cutaneous melanoma is on the rise in the United States, and the head and neck region is the primary site in 20% of patients. Lymph node status is the best indicator of prognosis for melanoma. In the head and neck, sentinel lymph node (SLN) biopsy presents particular challenges, with the parotid region posing difficulties that include locating the lymph nodes, less frequent visualization of blue dye, and the possibility of higher morbidity because of the proximity of lymph nodes to important neurovascular structures. Surgical approaches to the SLN dissection in the parotid region are variable, and may include superficial or total parotidectomies. Parotid-sparing SLN biopsies for head and neck melanomas were evaluated to determine rates of local recurrence. The charts of 301 patients from the Yale Melanoma Unit who underwent resection of their head and neck melanoma were reviewed. The location of the primary melanoma was noted, and the sentinel lymph node dissections from the operative reports were documented. Demographic and outcome data were recorded, including course of melanoma management, local recurrence, and postoperative course. Fifty-eight patients underwent SLN biopsy of lymph nodes in the parotid region. Parotid-sparing SLN biopsies comprised 94.8% of total surgical approaches for SLN biopsies in the parotid region. Of the remaining patients who underwent SLN biopsies in the parotid region, 5.17% had a superficial parotidectomy and none had a total parotidectomy. Sentinel lymph nodes were found in all depth layers of the parotid, and LNs were dissected out successfully without the need to remove the parotid in the most cases. The parotid region recurrence rate was 0% for SLN biopsies that either included or spared the parotid gland. There were no localized complications from the sentinel lymph node biopsies. The parotid-sparing SLN biopsy was performed without any local recurrence in the parotid region. The parotid-sparing SLN biopsy can be carried out in a safe, efficient manner without affecting the rate of local recurrence or postoperative complication. This less-invasive SLN biopsy procedure precludes the complications associated with parotidectomies and may reduce the morbidity for patients with melanomas of the head and neck.

Multidimensional Projections for Visual Analysis of Social Networks

Visual analysis of social networks is usually based on graph drawing algorithms and tools. However, social networks are a special kind of graph in the sense that interpretation of displayed relationships is heavily dependent on context. Context, in its turn, is given by attributes associated with graph elements, such as individual nodes, edges, and groups of edges, as well as by the nature of the connections between individuals. In most systems, attributes of individuals and communities are not taken into consideration during graph layout, except to derive weights for force-based placement strategies. This paper proposes a set of novel tools for displaying and exploring social networks based on attribute and connectivity mappings. These properties are employed to layout nodes on the plane via multidimensional projection techniques. For the attribute mapping, we show that node proximity in the layout corresponds to similarity in attribute, leading to easiness in locating similar groups of nodes. The projection based on connectivity yields an initial placement that forgoes force-based or graph analysis algorithm, reaching a meaningful layout in one pass. When a force algorithm is then applied to this initial mapping, the final layout presents better properties than conventional force-based approaches. Numerical evaluations show a number of advantages of pre-mapping points via projections. User evaluation demonstrates that these tools promote ease of manipulation as well as fast identification of concepts and associations which cannot be easily expressed by conventional graph visualization alone. In order to allow better space usage for complex networks, a graph mapping on the surface of a sphere is also implemented.

NONLOCAL ANALYSIS OF MODULAR ROLES

We introduce a new methodology to characterize the role that a given node plays inside the community structure of a complex network. Our method relies on the ability of the links to reduce the number of steps between two nodes in the network, which is measured by the number of shortest paths crossing each link, and its impact on the node proximity. In this way, we use node closeness to quantify the importance of a node inside its community. At the same time, we define a participation coefficient that depends on the shortest paths contained in the links that connect two communities. The combination of both parameters allows to identify the role played by the nodes in the network, following the same guidelines introduced by Guimerà et al. [Guimerà & Amaral, 2005] but, in this case, considering global information about the network. Finally, we give some examples of the hub characterization in real networks and compare our results with the parameters most used in the literature.

Extended Nodal Dissection Reduces Sexual Function Recovery After Robot-Assisted Laparoscopic Prostatectomy

Considering the anatomic proximity of the internal iliac lymph nodes and the pelvic plexus, it may be expected that more extensive pelvic nodal dissection is associated with an increased risk of damage to the small pelvis neural and vascular structures. We evaluate whether nodal dissection is associated with functional outcome after robot-assisted radical prostatectomy (RARP). In a series of 798 RARP procedures, 325 (40.7%) patients underwent a lymph node dissection. Continence, sexual function, and lower urinary tract symptoms (LUTS) were assessed using the International Consultation of Incontinence Questionnaire short form (ICIQ)-SF), International Index of Erectile Function-15, and European Organisation for Research and Treatment of Cancer Quality of Life Questionnaire (EORTC-QLQ)-PR25 questionnaires before and at 6 months intervals after RARP. Preoperative ICIQ-SF, IIEF-15, and PR25-LUTS scores were similar for men with and without nodal dissection. Normal postoperative erectile function (IIEF-EF >24) at 6 months was reported by 1.7%, 9.1%, and 50.4% of men with no, unilateral, and bilateral nerve preservation and normal preoperative erectile function. All domains of the IIEF-15 score showed a negative correlation with the number of removed lymph nodes. In 70 of 325 (21%) cases with nodal dissection, more than 10 nodes were removed. Men with more than 10 nodes removed had lower IIEF-15 domain scores compared with men with 1 to 10 removed lymph nodes. The postoperative ICIQ-SF and PR25-LUTS scores were not associated with extent of nodal dissection. Nodal metastases were found in 5.9% and 15.7% of men with ≤ 10 nodes and >10 nodes removed (P=0.005). In a multivariate analysis, extent of fascia preservation (FP-score), preoperative IIEF-EF, and number of removed nodes were the strongest independent predictors of postoperative erectile function recovery. More extensive nodal dissection was associated with impaired postoperative sexual function recovery but not continence and voiding function after RARP, independent of preoperative function and nerve preservation.

Dynamic relay-location-oriented group management in MMR WiMAX networks

Multihop wireless systems outperform single-hop ones in terms of coverage and capacity. The IEEE 802.16 standard, also known as Worldwide Interoperability for Microwave Access (WiMAX), is one of the latest broadband wireless access technologies over long distances. Mobile multihop relay (MMR) WiMAX networks introduce relay stations (RS) to improve range and performance at low cost. Providing multimedia capabilities to groups defined by node proximity is an interesting feature in tactical communications, which MMR WiMAX networks may support. This paper presents a dynamic group management scheme at the Medium Access Control (MAC) layer based on RS position, with dynamic RS selection, suitable for military environments where communications between close nodes are prioritary. The proposal is evaluated analytically and by simulations. Copyright © 2012 John Wiley & Sons, Ltd.

Comparison LEACH and HEED Cluster Based protocol for Wireless Senser Network

In the present paper wireless senser network for hierarchical network protocol of LEACH and HEED this is theory concept that how to data gathering. Our protocol aims to dynamically change the data Gathering period according to the Gathering quality. The timing scheme will find the minimum Gathering period that satisfies the sink’s request. This protocol is work on this and how to easy maintain from both of them. The LEACH (low energy adaptive clustering hierarchy) protocol presented in is an elegant solution where clusters are formed to fuse data before transmitting to the base station. We propose a new energy-efficient approach for clustering nodes in adhoc sensor networks. Based on this approach, we present a protocol, HEED (Hybrid Energy-Efficient Distributed clustering), that periodically selects cluster heads according to a hybrid of their residual energy and a secondary parameter, such as node proximity to its neighbors or node degree. In both routing protocol we differ which is batter to use and give most of the point to cover in this paper. Key words-Data Gathering, LEACH, HEED.

Lean Algebraic Multigrid (LAMG): Fast Graph Laplacian Linear Solver

Laplacian matrices of graphs arise in large-scale computational applications such as semisupervised machine learning; spectral clustering of images, genetic data, and web pages; transportation network flows; electrical resistor circuits; and elliptic partial differential equations discretized on unstructured grids with finite elements. A lean algebraic multigrid (LAMG) solver of the symmetric linear system $Ax=b$ is presented, where $A$ is a graph Laplacian. LAMG's run time and storage are empirically demonstrated to scale linearly with the number of edges. LAMG consists of a setup phase, during which a sequence of increasingly coarser Laplacian systems is constructed, and an iterative solve phase using multigrid cycles. General graphs pose algorithmic challenges not encountered in traditional multigrid applications. LAMG combines a lean piecewise-constant interpolation, judicious node aggregation based on a new node proximity measure (the affinity), and an energy correction of coarse-level systems. This results in fast convergence and substantial setup and memory savings. A serial LAMG implementation scaled linearly for a diverse set of 3774 real-world graphs with up to 47 million edges, with no parameter tuning. LAMG was more robust than the UMFPACK direct solver and combinatorial multigrid (CMG), although CMG was faster than LAMG on average. Our methodology is extensible to eigenproblems and other graph computations.

Analytical modelling in 802.11 ad hoc networks

This paper tries to bring together the physical model and protocol model that have been used to characterize interference relationship in an 802.11 ad hoc network. The physical model (known as the SNR model) is generally considered as a reference model for the physical layer behaviour but its application in wireless ad hoc networks is restricted by its complication. On the other hand, the protocol model (known as the unified disk graph) is straightforward but its validity is doubtful. We propose an analytical model for 802.11 ad hoc wireless networks where both the physical and protocol models are improved and modelled accurately by taking into accounts all emitters in the network and circumventing simplistic assumptions where communications are supposed to systematically fail if non-intended emitters fall in proximity of a receiver node. Our model consists in replacing a finite number of nodes by an equivalent continuum – characterized by a density of nodes – and disseminated in the network according to some distribution function. The key feature of the proposed model is that it permits taking into account the effect of interference, the CSMA/CA mechanism and radio propagation aspects in an easy and clear-cut way. All assumptions in the model are assessed with simulation results. Closed form formula of the signal to noise ratio and the throughput capacity per node will be given, corroborated by extensive simulation results in ns-2.

Bootstrap Node-Centered Proximity Identifier Selection for Structured Overlays in Private Networks

Distributed hash tables (DHTs) enable companies or campuses to use voice over IP (VoIP) systems in private networks at low cost. However, DHTs incur latency stretch caused by a topology mismatch between the application layer and the physical layer. Reducing this latency stretch is critical when implementing real-time applications that use DHTs, such as VoIP systems. This letter proposes a new method for reducing the latency stretch by creating node IDs, which form structured overlays that consider node proximity. Simulation results show that the proposed method is superior to Chord in terms of the distance between nodes, look-up path length, network burden, and look-up latency.

3D Mapping for Guide RF Ablation of Accessory Pathways Close Proximity of Atrioventricular Node and His Bundle

Anteroseptal and parahisian accessory pathway (AP) in the vicinity of the atrioventricular node (AVN) and the bundle of His, are associated with a high risk of complete atrioventricular block (AVB) during transcatheter radiofrequency ablation (RFA). Electro anatomical 3D mapping may be applied to avoid AVN and His bundle and reduce radiation exposure. We report 2 cases of AP that close proximity to AVN and His bundle using 3D EnSite NavX system. The first case was 35 year old lady with anteroseptal AP that conduct biderectonally. The AP was 16 mm away from His bundle. Both antegrade and retrograde conduction could be abolished with RF energy by of 3D mapping guidance. The procedure time was 65 minutes and the fluoroscopy time was 18 minutes. The second case was 22 year-old man with parahissian AP that only antegrade conduction. The distance between AP and His was about 3–4 mm. The AP could be successfully ablated using 3D mapping guide. The procedure time was 95 minutes and the fluoroscopy time was 20 minutes. In conclusion: RFA for patients with AP that close proximity to AV node and His bundle using 3D mapping guide is a feasible and effective radical therapy. This technique may reduce the risk of total AV block and radiation exposure.

Stereotactic body radiotherapy (SBRT): Technological innovation and application in gynecologic oncology

Objectives Stereotactic body radiotherapy (SBRT) is a novel form of noninvasive, highly conformal radiation treatment that delivers a high dose to tumor. The advantage of the technique resides in its ability to provide a high dose to tumor but spare normal tissues to an extent not previously possible. In this paper we will provide an introduction and review of this technology with regard to its use in gynecologic malignancies. Preliminary results from our experience are presented for the purpose of illustrating the range of SBRT applications in gynecologic oncology. Methods A comprehensive literature review was conducted and our experience from the past three years was reviewed. Results Six case series are published that report results of SBRT for gynecologic malignancies. Sixteen gynecologic patients have been treated with SBRT at our institution. Treatment sites include pelvic and periaortic nodes (9 patients), oligometastatic disease (2), and cervical or endometrial primary tumors when other conventional external radiation or brachytherapy techniques were unsuitable (5). Preliminary follow-up at a median of 11 months (range, 0.3–33 months) demonstrates 79% locoregional control, 43% distant failure, and 50% overall survival. Conclusions SBRT boosts to macroscopic periaortic node recurrences and other sites seem to provide local control and a possibility of long-term disease-free survival in carefully selected patients. Previously this had been difficult to achieve with conventional radiotherapy because of the proximity of periaortic nodes to small bowel. SBRT also offers a novel approach for minimally invasive treatment in the management of gynecological cancer where current surgical and radiotherapy techniques are unsuitable.