Increasing Node Count Research Articles

An Energy-aware Ad-hoc Routing Strategy for Queriable Wireless Sensor Networks

The data volume handled by wireless sensor networks (WSN) is ever growing due to increasing node counts and node complexity – be it in traditional WSN applications or for Car2X or Internet-of-Things. Queriable WSN are a concept to handle the large data volumes in such networks by abstracting the network as a virtual database table to which users can pose queries. This declarative approach enables networks which can flexibly adapt to changing application requirements. In addition they possess a flat learning curve since users do not need to have a high technological understanding of the sensor node firmware. Upon executing a query it is first propagated through the network and once it has reached the desired nodes, results are collected and send back through the query-posing node (usually the sink). The routing which is used for the data aggregation step plays a major role in the energy efficiency in networks with increasing node and sensor value counts as represented by Car2X networks for instance. In this paper, an ad-hoc routing strategy for queriable WSN is proposed which is both energy-aware and application-specific. It will be shown that this routing can contribute greatly towards decreasing the energy consumption needed for data aggregation and thus helps increasing the network’s lifespan.

Retention of viability by fragmented invasive Crassula helmsii, Elodea canadensis and Lagarosiphon major

AbstractInvasive aquatic macrophytes tend to reproduce and spread through vegetative means, often via fragmentary propagules. Dispersal among aquatic sites may occur overland via attachment to various vectors, or within river systems by directional water currents. However, for many species the relationship between fragment size and resumption of growth is unknown. Here, we assessed resumption of growth of apical and mid‐stem fragments of invasive Crassula helmsii, Elodea canadensis and Lagarosiphon major. Proportionally, apical fragments tended to more readily resume growth than mid‐stem sections, especially for E. canadensis and L. major (80–100%). However, viability did not scale linearly with increasing fragment size, which suggests that fragment size is not a singular determinant of propagule fitness. Nevertheless, longer fragments generally produced greater numbers of shoots and roots, but root production significantly differed among species and was determined through an interaction between plant section, species and fragment length. Overall, all species produced new shoots and roots from fragments as small as 10 mm. C. helmsii mid‐stem fragments standardised by node counts did not display new growth (up to 10 nodes), while E. canadensis tended to show greater shoot and root production with increasing node counts. It is evident that a medium to high proportion of small fragmentary propagules of these invasive macrophytes can retain viability. These data have clear implications for understanding the dispersal of these invasive species and their management. Specifically, cutting and dredging may increase rather than decrease infestations, especially in downstream directions. Thus, in the absence of adequate fragment containment, current short‐term control strategies may in fact be counterproductive.

Applying Parallel Computing Techniques to Analyze Terabyte Atmospheric Boundary Layer Model Outputs

In the atmospheric sciences, the size of simulation output continues to grow as computational resources able to handle simulations with fine-scale spatial and temporal resolutions become more accessible. As output size increases, serial data analysis methods become overwhelmed, resulting in either long delays during processing or total failures due to memory constraints. Parallel data analysis methods can alleviate these issues, however atmospheric scientists are often unfamiliar with how to achieve this. Therefore, example methods are needed to help guide the use of parallel processing in the analysis of Big Data from atmospheric simulations. In this work, practical methods are presented by which an analysis may be executed in parallel using the Message Passing Interface (MPI) and Python. These methods first consider the inherent spatial dependencies of a particular data analysis process. By identifying these dependencies, horizontal or vertical distribution of the dataset across processes can be carried out with minimal process intercommunication. In addition, an analysis method is classified as either data-transfer-limited or computationally-limited. In data-transfer-limited problems, data transfer time outweighs processing time. In computationally-limited problems, processing time outweighs data transfer time. The results show that by increasing processor count, the execution time of computationally-limited problems shows improvement. For data-transfer-limited problems, increasing node count offers the greatest improvement. To further improve the performance of computationally-limited problems, a Graphics Processing Unit (GPU) and the Compute Unified Device Architecture (CUDA) framework are used. It is shown that this GPU implementation offers further improvement over the MPI version of the analysis methods tested.

Number of Lymph Nodes in Primary Nodal Basin and a "Second Look" Protocol as Quality Indicators for Optimal Nodal Staging of Colon Cancer.

-Evaluation of 12 or more lymph nodes (LNs) is currently used as a quality indicator for adequacy of pathologic examination of colon cancer resections. -To evaluate the utility of a focused LN search in the immediate vicinity of the tumor and a "second look" protocol in improving LN staging in colon cancer. -Lymph nodes were submitted separately from the primary nodal basin (PNB) and secondary nodal basin (SNB) defined as an area less than 5 cm away and an area greater than 5 cm away from the tumor edge, respectively, in 201 consecutive resections (2010-2013). One hundred sixty-eight consecutive tumors (2006-2009) were used as a control group. A second search was performed in all cases that were N0 after the first search. -In cases that were N0 after the first search, 20.9 ± 10.8 LNs were collected from the PNB, compared to 8.5 ± 9.1 from the SNB. Positive LNs were found in N+ tumors in the PNB in all cases but in only 9% (4 of 46) of SNBs (P < .001). A second search increased node count by an average of 10 additional LNs. In 5 of 114 cases (4.4%), N0 after the first search converted to N+ after a second search that yielded 1 to 4 positive LNs, all of which were in the PNB. -Emphasis on the number of LNs examined from the PNB and a "second look" protocol improve nodal staging.

Vectorised graphics processing unit accelerated dynamic relaxation for bar and beam elements

Dynamic relaxation is an analysis method that can be used to find the static equilibrium state of a structure undergoing large displacements. Due to the algorithm's iterative nature, which derives from a damped dynamic oscillations approach, it can take considerable time when solving models with dense node counts. This research looks at a vectorised dynamic relaxation implementation, executed on a graphics card's processing unit (GPU) for the most computationally demanding calculations, and compared to traditional computations on the central processing unit (CPU), to determine if time savings can be found with the change in processor type. The programming language Python and module PyCUDA are utilised on a desktop graphics card with over two thousand shader cores, and compared to a quad-core processor using the same code layout. A vectorised formulation for bar elements and reduced degree-of-freedom beam elements is used, to analyse the absolute and relative run-times for three benchmark cases. It is found that for models with low node counts, the CPU is faster, while for medium to highly dense models, the GPU acceleration can reduce absolute run-times by a factor of three to just over eight. Most benefit is gained when the executed code allows the GPU cores to be overloaded, such that complex calculations involving large arrays of data can be spread over the many cores. This was evident in the GPU load demand, which increased steadily with increasing node count but remained below 100%, while the CPU was readily activated to maximum load for even simple models. The time savings are of interest to architects, engineers and researchers utilising the dynamic relaxation method with medium to complex models, as the benefits can be harnessed with minimal code alteration.

Suitability of Data Intensive Application in a Bandwidth Constrained Global Grid Network

Problem statement: To check the suitability of real time data intensive applications in a global grid network. Approach: With improved bandwidth availability, taking the grid to the internet is becoming a reality. However issues’ regarding the security and bandwidth utilization needs to be understood as these factors become crucial to the success of the grid as a commercial model. Results: Here in this research work we investigate the effect of data intensive applications running in a grid with different number of nodes under constrained bandwidth. Conclusion/Recommendations: Our simulation shows that increasing node count does not guarantee improved quality of service.

V477 EXTRAPERITONEAL EXTENDED LYMPH NODE DISSECTION DURING ROBOTIC ASSISTED RADICAL PROSTATECTOMY: TECHNICAL CAVEATS

You have accessJournal of UrologyProstate Oncology1 Apr 2010V477 EXTRAPERITONEAL EXTENDED LYMPH NODE DISSECTION DURING ROBOTIC ASSISTED RADICAL PROSTATECTOMY: TECHNICAL CAVEATS Ahmed Ghazi, Mathew Lux, Hitendra Patel, and Jean Joseph Ahmed GhaziAhmed Ghazi More articles by this author , Mathew LuxMathew Lux More articles by this author , Hitendra PatelHitendra Patel More articles by this author , and Jean JosephJean Joseph More articles by this author View All Author Informationhttps://doi.org/10.1016/j.juro.2010.02.551AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookTwitterLinked InEmail INTRODUCTION AND OBJECTIVES The superiority of extended pelvic lymph node dissection (ELND) in increasing node count and potentially detecting lymph node metastasis in patients with prostate cancer has been reported by several authors. Unlike open prostatectomy which is performed extraperitoneally, a transperitoneal route is often used by surgeons using a laparoscopic or robot assisted approach, due to concerns over poor exposure, and the increased risk of lymphocele. Our objective is to demonstrate several technical caveats to facilitate an ELND during robot assisted radical prostatectomy (RARP), performed extraperitoneally METHODS A 50-year old man presented with stage T1c prostate cancer, with a Gleason score 3+4, and a PSA of 4.1. Staging pelvic CT scan showed an enlarged 11.4 mm external iliac node. He underwent an ELND followed by RARP using an extraperitoneal approach. A 0 and 30-degree scopes are used to facilitate visualization during the caudal and cranial dissection respectively. RESULTS Bilateral ELND was carried out successfully. Boundaries of the template included the common iliac bifurcation (proximally), the genitofemoral nerve (laterally), the circumflex iliac vein and lymph node of Cloquet (distally), the hypogastric vessels (posteriorly) and the obturator fossa (medially) bilaterally. Clips were used to control the lymphatic channels. The number of lymph nodes retrieved was 25 on the right and 14 on the left side. No metastasis was detected on either side. CONCLUSIONS The extraperitoneal approach does not hinder the extent of lymph node dissection during robot assisted radical prostatectomy. Using a 30 degree angled down scope facilitates the proximal nodal dissection. Meticulous clipping limits the risk of lymphocele formation. Rochester, NY© 2010 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 183Issue 4SApril 2010Page: e188 Advertisement Copyright & Permissions© 2010 by American Urological Association Education and Research, Inc.MetricsAuthor Information Ahmed Ghazi More articles by this author Mathew Lux More articles by this author Hitendra Patel More articles by this author Jean Joseph More articles by this author Expand All Advertisement Advertisement PDF downloadLoading ...

An Evaluation of the Relationship Between Lymph Node Number and Staging in pT3 Colon Cancer Using Population-Based Data

The number of lymph nodes examined has been proposed as a quality benchmark for colon cancer surgery, although it is unknown whether this strategy reduces understaging. We identified 11,044 patients who underwent surgery for colon cancer with pT3 wall penetration between 1988 and 2003 from the Surveillance, Epidemiology and End Results cancer registry. We determined the proportion of patients who were node positive for each node count. We used logistic regression to predict the odds of being node positive by node count after adjusting for confounders. We used joinpoint analysis to determine whether there was a consistent relationship between node count and the odds of being node positive. The proportion of patients found to be node positive increased with node count at low counts (<or=5-6 nodes), but patients with 7 nodes identified were as likely to be node positive as patients with 30 or more nodes (odds ratio = 0.97; 95% CI = 0.90-1.05). Joinpoint analysis demonstrated a dramatic increase in odds of node positivity with increasing node count to 5 nodes (slope = 0.2; P < .0001). Between 6 and 13 nodes there was a marginal increase in odds of positive nodes (slope = 0.03; P = .006), but when more nodes were evaluated, odds of node positivity actually declined (slope = -0.01; P = .04). Staging of pT3 colon cancer improves with increasing node count, but only when the node count is low (<5-7 nodes). At higher counts, an increased node count has marginal effects on staging.

Staging error does not explain the relationship between the number of lymph nodes in a colon cancer specimen and survival

Survival in colon cancer is greater in those patients who have more lymph nodes identified at resection and may be due to stage migration, confounding by treatment, social, or clinical characteristics. Identifying factor(s) responsible for the effect may represent an opportunity to improve quality of care for patients with colon cancer by increasing node counts in specimens. Cox proportional hazards models were created to analyze survival of 11,399 patients with stage I-III colon cancer from the Surveillance, Epidemiology and End Results (SEER)-Medicare database. The primary predictor variable was the number of lymph nodes identified. The models allowed adjustment for patient factors, use of chemotherapy, surgical specialty, and the average number of nodes identified by surgeon and hospital pathologist. The number of nodes identified was related to survival. Compared to those with less than 7 nodes, patients with 7 to 11 nodes had a 13% lesser risk of death (hazard ratio [HR], 0.87; 95% confidence interval [CI], 0.76-0.99; P = .037). Patients with more than 12 nodes had a 17% lesser risk (HR, 0.83; 95% CI, 0.73-0.95; P = .005). Adjusting for selected patient demographic characteristics, receipt of chemotherapy, surgical specialty, and the average number of nodes identified per specimen by the surgeon or hospital did not significantly alter the relationship between number of nodes and survival. These findings argue against understaging or confounding as the explanation for the inferior survival observed in patients with fewer nodes identified. National initiatives to increase the number of nodes identified in colon cancer specimens may not improve substantially the cancer-specific outcomes.

1038 Staging Error Does Not Explain the Relationship Between the Number of Nodes in a Colon Cancer Specimen and Survival

Background. Survival in colon cancer is greater in those patients who have more lymph nodes identified at resection and may be due to stage migration, confounding by treatment, social, or clinical characteristics. Identifying factor(s) responsible for the effect may represent an opportunity to improve quality of care for patients with colon cancer by increasing node counts in specimens. Methods. Cox proportional hazards models were created to analyze survival of 11,399 patients with stage I-III colon cancer from the Surveillance, Epidemiology and End Results (SEER)-Medicare database. The primary predictor variable was the number of lymph nodes identified. The models allowed adjustment for patient factors, use of chemotherapy, surgical specialty, and the average number of nodes identified by surgeon and hospital pathologist. Results. The number of nodes identified was related to survival. Compared to those with less than 7 nodes, patients with 7 to 11 nodes had a 13% lesser risk of death (hazard ratio [HR], 0.87; 95% confidence interval [CI], 0.76--0.99; P = .037). Patients with more than 12 nodes had a 17% lesser risk (HR, 0.83; 95% CI, 0.73--0.95; P = .005). Adjusting for selected patient demographic characteristics, receipt of chemotherapy, surgical specialty, and the average number of nodes identified per specimen by the surgeon or hospital did not significantly alter the relationship between number of nodes and survival. Conclusion. These findings argue against understaging or confounding as the explanation for the inferior survival observed in patients with fewer nodes identified. National initiatives to increase the number of nodes identified in colon cancer specimens may not improve substantially the cancer-specific outcomes. (Surgery 2010;147:358-65.)

Hierarchical routing overhead in mobile ad hoc networks

Hierarchical techniques have long been known to afford scalability in networks. By summarizing topology detail via a hierarchical map of the network topology, network nodes are able to conserve memory and link resources. Extensive analysis of the memory requirements of hierarchical routing was undertaken in the 1970s. However, there has been little published work that assesses analytically the communication overhead incurred in hierarchical routing. This paper assesses the scalability, with respect to increasing node count, of hierarchical routing in mobile ad hoc networks (MANETs). The performance metric of interest is the number of control packet transmissions per second per node (/spl Phi/). To derive an expression for /spl Phi/, the components of hierarchical routing that incur overhead as a result of hierarchical cluster formation and location management are identified. It is shown here that /spl Phi/ is only polylogarithmic in the node count.