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Sample records for hoc within-woman analysis

  1. Ad Hoc Networks: Headline 2000 Communications Analysis

    NASA Astrophysics Data System (ADS)

    Blair, W. D.; Reynolds, A. B.

    2002-06-01

    This report examines unit location data and terrain from Headline 2000 to investigate communications networks within the maneuver units. Within the Enhanced Combat Force timeframe, such units would be supported by a Tactical Data Distribution Sub-system (TDDS). This is envisaged as an ad hoc network changing its topology as units maneuver across the battlespace. The report describes approaches that can be applied to Headline 2000 and other data to characterize the nature of the network topology, both statically and as it changes over time, in order to explore the impact on the TDDS network capacity and hence to hence to assist in elucidating consequent requirements of a candidate TDDS.

  2. Performance Analysis of Ad Hoc Routing Protocols in City Scenario for VANET

    NASA Astrophysics Data System (ADS)

    Das, Sanjoy; Raw, Ram Shringar; Das, Indrani

    2011-12-01

    In this paper, performance analysis of Location Aided Routing (LAR), AODV and DSR protocol in city scenarios has been done. The mobility model considered is Manhattan model. This mobility model used to emulate the movement pattern of nodes i.e., vehicles on streets defined by maps. Our objective is to provide a comparative analysis among LAR, AODV and DSR protocol in city scenarios in Vehicular Ad hoc Networks. The simulation work has been conducted using the Glomosim 2.03 simulator. The results show that LAR1 protocol achieves maximum packet delivery ratio is 100% in the sparsely populated network. The delay is maximum in AODV 121.88 ms when the number of node is 10 in the network. The results show that LAR1 outperform DSR and AODV in term of packet delivery ratio and end to end delay.

  3. Analysis of a distributed algorithm to determine multiple routes with path diversity in ad hoc networks.

    SciTech Connect

    Ghosal, Dipak; Mueller, Stephen Ng

    2005-04-01

    With multipath routing in mobile ad hoc networks (MANETs), a source can establish multiple routes to a destination for routing data. In MANETs, mulitpath routing can be used to provide route resilience, smaller end-to-end delay, and better load balancing. However, when the multiple paths are close together, transmissions of different paths may interfere with each other, causing degradation in performance. Besides interference, the physical diversity of paths also improves fault tolerance. We present a purely distributed multipath protocol based on the AODV-Multipath (AODVM) protocol called AODVM with Path Diversity (AODVM/PD) that finds multiple paths with a desired degree of correlation between paths specified as an input parameter to the algorithm. We demonstrate through detailed simulation analysis that multiple paths with low degree of correlation determined by AODVM/PD provides both smaller end-to-end delay than AODVM in networks with low mobility and better route resilience in the presence of correlated node failures.

  4. Does Ad Hoc Coronary Intervention Reduce Radiation Exposure? – Analysis of 568 Patients

    PubMed Central

    Truffa, Márcio A. M.; Alves, Gustavo M.P.; Bernardi, Fernando; Esteves Filho, Antonio; Ribeiro, Expedito; Galon, Micheli Z.; Spadaro, André; Kajita, Luiz J.; Arrieta, Raul; Lemos, Pedro A.

    2015-01-01

    Background Advantages and disadvantages of ad hoc percutaneous coronary intervention have been described. However little is known about the radiation exposure of that procedure as compared with the staged intervention. Objective To compare the radiation dose of the ad hoc percutaneous coronary intervention with that of the staged procedure Methods The dose-area product and total Kerma were measured, and the doses of the diagnostic and therapeutic procedures were added. In addition, total fluoroscopic time and number of acquisitions were evaluated. Results A total of 568 consecutive patients were treated with ad hoc percutaneous coronary intervention (n = 320) or staged percutaneous coronary intervention (n = 248). On admission, the ad hoc group had less hypertension (74.1% vs 81.9%; p = 0.035), dyslipidemia (57.8% vs. 67.7%; p = 0.02) and three-vessel disease (38.8% vs. 50.4%; p = 0.015). The ad hoc group was exposed to significantly lower radiation doses, even after baseline characteristic adjustment between both groups. The ad hoc group was exposed to a total dose-area product of 119.7 ± 70.7 Gycm2, while the staged group, to 139.2 ± 75.3 Gycm2 (p < 0.001). Conclusion Ad hoc percutaneous coronary intervention reduced radiation exposure as compared with diagnostic and therapeutic procedures performed at two separate times. PMID:26351982

  5. Efficacy response in CF patients treated with ivacaftor: post-hoc analysis.

    PubMed

    Konstan, Michael W; Plant, Barry J; Elborn, J Stuart; Rodriguez, Sally; Munck, Anne; Ahrens, Richard; Johnson, Charles

    2015-05-01

    Clinical studies in patients with cystic fibrosis and G551D-CFTR showed that the group treated with ivacaftor had improved clinical outcomes. To better understand the effect of ivacaftor therapy across the distribution of individual FEV(1) responses, data from Phase 3 studies (STRIVE/ENVISION) were re-examined. In this post-hoc analysis of patients (n = 209) who received 48 weeks of ivacaftor or placebo, patients were assigned to tertiles according to FEV(1) response. These groups were then used to evaluate response (FEV(1), sweat chloride, weight, CFQ-R, and pulmonary exacerbation). The number needed to treat (NNT) was calculated for specific thresholds for each outcome. Across all tertiles, numerical improvements in FEV(1), sweat chloride, CFQ-R and the frequency of pulmonary exacerbations were observed in ivacaftor-treated patients: the treatment difference versus placebo was statistically significant for all outcomes in the upper tertile and for some outcomes in the lower and middle tertiles. The NNT for a ≥ 5% improvement in %predicted FEV(1) was 1.90, for a ≥ 5% body weight increase was 5.74, and to prevent a pulmonary exacerbation was 3.85. This analysis suggests that the majority of patients with clinical characteristics similar to STRIVE/ENVISION patients have the potential to benefit from ivacaftor therapy. PMID:25755212

  6. A Post Hoc Analysis of D-Threo-Methylphenidate Hydrochloride (Focalin) Versus D,l-Threo-Methylphenidate Hydrochloride (Ritalin)

    ERIC Educational Resources Information Center

    Weiss, Margaret; Wasdell, Michael; Patin, John

    2004-01-01

    Objective: To evaluate clinical measures of the benefit/risk ratio in a post hoc analysis of a clinical trial of d-threo-methylphenidate hydrochloride (d-MPH) and d,l-threo-methylphenidate hydrochloride (d,l-MPH). Method: Data from a phase III clinical trial was used to compare equimolar doses of d-MPH and d,l-MPH treatment for…

  7. Ad hoc supervision of general practice registrars as a 'community of practice': analysis, interpretation and re-presentation.

    PubMed

    Clement, T; Brown, J; Morrison, J; Nestel, D

    2016-05-01

    General practice registrars in Australia undertake most of their vocational training in accredited general practices. They typically see patients alone from the start of their community-based training and are expected to seek timely ad hoc support from their supervisor. Such ad hoc encounters are a mechanism for ensuring patient safety, but also provide an opportunity for learning and teaching. Wenger's (Communities of practice: learning, meaning, and identity. Cambridge University Press, New York, 1998) social theory of learning ('communities of practice') guided a secondary analysis of audio-recordings of ad hoc encounters. Data from one encounter is re-presented as an extended sequence to maintain congruence with the theoretical perspective and enhance vicariousness. An interpretive commentary communicates key features of Wenger's theory and highlights the researchers' interpretations. We argue that one encounter can reveal universal understandings of clinical supervision and that the process of naturalistic generalisation allows readers to transfer others' experiences to their own contexts. The paper raises significant analytic, interpretive, and representational issues. We highlight that report writing is an important, but infrequently discussed, part of research design. We discuss the challenges of supporting the learning and teaching that arises from adopting a socio-cultural lens and argue that such a perspective importantly captures the complex range of issues that work-based practitioners have to grapple with. This offers a challenge to how we research and seek to influence work-based learning and teaching in health care settings. PMID:26384813

  8. Analysis and Proposal of Position-Based Routing Protocols for Vehicular Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Okada, Hiraku; Takano, Akira; Mase, Kenichi

    One of the most promising applications of a mobile ad hoc network is a vehicular ad hoc network (VANET). Each vehicle is aware of its position information by GPS or other methods, so position-based routing is a useful approach in VANET. The position-based routing protocol can be classified roughly into a next-hop forwarding method and a directed flooding method. We evaluate performance of both methods by analytic approach and compare them in this paper. From the evaluation results, we conclude that it is effective for the position-based routing to choose either the next-hop forwarding method or the directed flooding method according to the environment. Then we propose the hybrid transmission method which can select one of them according to the environment, and clarify that the proposed method can keep the packet delivery ratio at a high level and reduce the delay time.

  9. Clinical Factors Associated with Dose of Loop Diuretics After Pediatric Cardiac Surgery: Post Hoc Analysis.

    PubMed

    Haiberger, Roberta; Favia, Isabella; Romagnoli, Stefano; Cogo, Paola; Ricci, Zaccaria

    2016-06-01

    A post hoc analysis of a randomized controlled trial comparing the clinical effects of furosemide and ethacrynic acid was conducted. Infants undergoing cardiac surgery with cardiopulmonary bypass were included in order to explore which clinical factors are associated with diuretic dose in infants with congenital heart disease. Overall, 67 patients with median (interquartile range) age of 48 (13-139) days were enrolled. Median diuretic dose was 0.34 (0.25-0.4) mg/kg/h at the end of postoperative day (POD) 0 and it significantly decreased (p = 0.04) over the following PODs; during this period, the ratio between urine output and diuretic dose increased significantly (p = 0.04). Age (r -0.26, p = 0.02), weight (r -0.28, p = 0.01), cross-clamp time (r 0.27, p = 0.03), administration of ethacrynic acid (OR 0.01, p = 0.03), and, at the end of POD0, creatinine levels (r 0.3, p = 0.009), renal near-infrared spectroscopy saturation (-0.44, p = 0.008), whole-blood neutrophil gelatinase-associated lipocalin levels (r 0.30, p = 0.01), pH (r -0.26, p = 0.02), urinary volume (r -0.2755, p = 0.03), and fluid balance (r 0.2577, p = 0.0266) showed a significant association with diuretic dose. At multivariable logistic regression cross-clamp time (OR 1.007, p = 0.04), use of ethacrynic acid (OR 0.2, p = 0.01) and blood pH at the end of POD0 (OR 0.0001, p = 0.03) was independently associated with diuretic dose. Early resistance to loop diuretics continuous infusion is evident in post-cardiac surgery infants: Higher doses are administered to patients with lower urinary output. Independently associated variables with diuretic dose in our population appeared to be cross-clamping time, the administration of ethacrynic acid, and blood pH. PMID:26961571

  10. Efficacy of octreotide long-acting repeatable in neuroendocrine tumors: RADIANT-2 placebo arm post hoc analysis

    PubMed Central

    Strosberg, Jonathan R; Yao, James C; Bajetta, Emilio; Aout, Mounir; Bakker, Bert; Hainsworth, John D; Ruszniewski, Philippe B; Van Cutsem, Eric; Öberg, Kjell; Pavel, Marianne E

    2015-01-01

    Somatostatin analogues (SSA) have demonstrated antiproliferative activity in addition to efficacy for carcinoid symptom control in functional neuroendocrine tumors (NET). A post hoc analysis of the placebo arm of the RAD001 In Advanced Neuroendocrine Tumors-2 (RADIANT-2) study was conducted to assess the efficacy of octreotide long-acting repeatable (LAR) on progression-free survival (PFS) and overall survival (OS) estimated using the Kaplan–Meier method. Out of 213 patients randomized to placebo plus octreotide LAR in RADIANT-2, 196 patients with foregut, midgut, or hindgut NET were considered for present analysis. Of these, 41 patients were SSA-treatment naïve and 155 had received SSA therapy before study entry. For SSA-naïve patients, median PFS by adjudicated central review was 13.6 (95% CI 8.2–22.7) months. For SSA-naïve patients with midgut NET (n=24), median PFS was 22.2 (95% CI 8.3–29.5) months. For patients who had received SSA previously, the median PFS was 11.1 (95% CI 8.4–14.3) months. Among the SSA-pretreated patients who had midgut NET (n=119), the median PFS was 12.0 (95% CI 8.4–19.3) months. Median OS was 35.8 (95% CI 32.5–48.9) months for patients in the placebo plus octreotide LAR arm; 50.6 (36.4 – not reached) months for SSA-naïve patients and 33.5 (95% CI 27.5–44.7) months for those who had received prior SSA. This post hoc analysis of the placebo arm of the large phase 3 RADIANT-2 study provides data on PFS and OS among patients with progressive NET treated with octreotide therapy. PMID:26373569

  11. Ad Hoc Supervision of General Practice Registrars as a "Community of Practice": Analysis, Interpretation and Re-Presentation

    ERIC Educational Resources Information Center

    Clement, T.; Brown, J.; Morrison, J.; Nestel, D.

    2016-01-01

    General practice registrars in Australia undertake most of their vocational training in accredited general practices. They typically see patients alone from the start of their community-based training and are expected to seek timely ad hoc support from their supervisor. Such ad hoc encounters are a mechanism for ensuring patient safety, but also…

  12. Prophylactic Azithromycin Therapy After Lung Transplantation: Post hoc Analysis of a Randomized Controlled Trial.

    PubMed

    Ruttens, D; Verleden, S E; Vandermeulen, E; Bellon, H; Vanaudenaerde, B M; Somers, J; Schoonis, A; Schaevers, V; Van Raemdonck, D E; Neyrinck, A; Dupont, L J; Yserbyt, J; Verleden, G M; Vos, R

    2016-01-01

    Prophylactic azithromycin treatment has been demonstrated to improve freedom from bronchiolitis obliterans syndrome (BOS) 2 years after lung transplantation (LTx). In the current study, we re-evaluated the long-term effects of this prophylactic approach in view of the updated classification system for chronic lung allograft dysfunction (CLAD). A retrospective, intention-to-treat analysis of a randomized controlled trial comparing prophylactic treatment with placebo (n = 43) versus azithromycin (n = 40) after LTx was performed. Graft dysfunction (CLAD), graft loss (retransplantation, mortality), evolution of pulmonary function and functional exercise capacity were analyzed 7 years after inclusion of the last study subject. Following LTx, 22/43 (51%) patients of the placebo group and 11/40 (28%) patients of the azithromycin group ever developed CLAD (p = 0.043). CLAD-free survival was significantly longer in the azithromycin group (p = 0.024). No difference was present in proportion of obstructive versus restrictive CLAD between both groups. Graft loss was similar in both groups: 23/43 (53%) versus 16/40 (40%) patients (p = 0.27). Long-term pulmonary function and functional exercise capacity were significantly better in the azithromycin group (p < 0.05). Prophylactic azithromycin therapy reduces long-term CLAD prevalence and improves CLAD-free survival, pulmonary function, and functional exercise capacity after LTx. PMID:26372728

  13. Polypharmacy and effects of apixaban versus warfarin in patients with atrial fibrillation: post hoc analysis of the ARISTOTLE trial

    PubMed Central

    Brouwer, Marc A; Wojdyla, Daniel M; Thomas, Laine; Lopes, Renato D; Washam, Jeffrey B; Lanas, Fernando; Xavier, Denis; Husted, Steen; Wallentin, Lars; Alexander, John H; Granger, Christopher B; Verheugt, Freek W A

    2016-01-01

    Objective To determine whether the treatment effect of apixaban versus warfarin differs with increasing numbers of concomitant drugs used by patients with atrial fibrillation. Design Post hoc analysis performed in 2015 of results from ARISTOTLE (apixaban for reduction in stroke and other thromboembolic events in atrial fibrillation)—a multicentre, double blind, double dummy trial that started in 2006 and ended in 2011. Participants 18 201 ARISTOTLE trial participants. Interventions In the ARISTOTLE trial, patients were randomised to either 5 mg apixaban twice daily (n=9120) or warfarin (target international normalised ratio range 2.0-3.0; n=9081). In the post hoc analysis, patients were divided into groups according to the number of concomitant drug treatments used at baseline (0-5, 6-8, ≥9 drugs) with a median follow-up of 1.8 years. Main outcome measures Clinical outcomes and treatment effects of apixaban versus warfarin (adjusted for age, sex, and country). Results Each patient used a median of six drugs (interquartile range 5-9); polypharmacy (≥5 drugs) was seen in 13 932 (76.5%) patients. Greater numbers of concomitant drugs were used in older patients, women, and patients in the United States. The number of comorbidities increased across groups of increasing numbers of drugs (0-5, 6-8, ≥9 drugs), as did the proportions of patients treated with drugs that interact with warfarin or apixaban. Mortality also rose significantly with the number of drug treatments (P<0.001), as did rates of stroke or systemic embolism (1.29, 1.48, and 1.57 per 100 patient years, for 0-5, 6-8, and ≥9 drugs, respectively) and major bleeding (1.91, 2.46, and 3.88 per 100 patient years, respectively). Relative risk reductions in stroke or systemic embolism for apixaban versus warfarin were consistent, regardless of the number of concomitant drugs (Pinteraction=0.82). A smaller reduction in major bleeding was seen with apixaban versus warfarin with increasing numbers

  14. The Efficacy Profile of Rotigotine During the Waking Hours in Patients With Advanced Parkinson's Disease: A Post Hoc Analysis

    PubMed Central

    LeWitt, Peter A.; Poewe, Werner; Elmer, Lawrence W.; Asgharnejad, Mahnaz; Boroojerdi, Babak; Grieger, Frank; Bauer, Lars

    2016-01-01

    Objectives Transdermal delivery of rotigotine maintains stable plasma concentrations for 24 hours. Three phase 3 studies of rotigotine as add-on to levodopa in advanced Parkinson's disease showed a significant reduction in “off” time from baseline to end of maintenance (EoM). However, detailed analyses over the range of a day have not yet been performed. The objective was to examine the time course of the efficacy profile of rotigotine throughout the day. Methods Post hoc analysis of diary data from 3 double-blind, placebo-controlled studies of rotigotine in patients with advanced Parkinson's disease inadequately controlled with levodopa, with average “off” time of ≥2.5 h/d (CLEOPATRA-PD [NCT00244387], 16-week maintenance; PREFER, 24-week maintenance; SP921 [NCT00522379], 12-week maintenance). Patients marked 30-minute intervals as “off,” “on without troublesome dyskinesia,” “on with troublesome dyskinesia,” or “sleep.” Diaries completed on the 3 days before EoM were analyzed. A 2-sample t test was performed for comparison of rotigotine + levodopa versus placebo + levodopa for mean percentage of time per status during four 6-hour periods: 12:00am (midnight) to 6:00am, 6:00am to 12:00pm (noon), noon to 6:00pm, and 6:00pm to midnight. Results Data were available for 967 patients (placebo + levodopa, 260; rotigotine + levodopa, 707). During the 24-hour period at EoM, an advantage in mean percentage time spent “off” and “on without troublesome dyskinesia” was observed with rotigotine + levodopa versus placebo + levodopa during the three 6-hour periods from 6:00am to midnight (P < 0.05; exploratory analysis). Conclusions These exploratory analyses of patients with motor fluctuations suggest that the efficacy of rotigotine transdermal patch, as captured by diary data, in reducing “off” time and increasing “on time without troublesome dyskinesia” may cover the full waking day. PMID:26882318

  15. A novel method to prioritize RNAseq data for post-hoc analysis based on absolute changes in transcript abundance.

    PubMed

    McNutt, Patrick; Gut, Ian; Hubbard, Kyle; Beske, Phil

    2015-06-01

    The use of fold-change (FC) to prioritize differentially expressed genes (DEGs) for post-hoc characterization is a common technique in the analysis of RNA sequencing datasets. However, the use of FC can overlook certain population of DEGs, such as high copy number transcripts which undergo metabolically expensive changes in expression yet fail to exceed the ratiometric FC cut-off, thereby missing potential important biological information. Here we evaluate an alternative approach to prioritizing RNAseq data based on absolute changes in normalized transcript counts (ΔT) between control and treatment conditions. In five pairwise comparisons with a wide range of effect sizes, rank-ordering of DEGs based on the magnitude of ΔT produced a power curve-like distribution, in which 4.7-5.0% of transcripts were responsible for 36-50% of the cumulative change. Thus, differential gene expression is characterized by the high production-cost expression of a small number of genes (large ΔT genes), while the differential expression of the majority of genes involves a much smaller metabolic investment by the cell. To determine whether the large ΔT datasets are representative of coordinated changes in the transcriptional program, we evaluated large ΔT genes for enrichment of gene ontologies (GOs) and predicted protein interactions. In comparison to randomly selected DEGs, the large ΔT transcripts were significantly enriched for both GOs and predicted protein interactions. Furthermore, enrichments were were consistent with the biological context of each comparison yet distinct from those produced using equal-sized populations of large FC genes, indicating that the large ΔT genes represent an orthagonal transcriptional response. Finally, the composition of the large ΔT gene sets were unique to each pairwise comparison, indicating that they represent coherent and context-specific responses to biological conditions rather than the non-specific upregulation of a family of genes

  16. The “Gender Factor” in Wearing-Off among Patients with Parkinson's Disease: A Post Hoc Analysis of DEEP Study

    PubMed Central

    Colombo, Delia; Abbruzzese, Giovanni; Antonini, Angelo; Barone, Paolo; Bellia, Gilberto; Franconi, Flavia; Attar, Mahmood; Zagni, Emanuela; Haggiag, Shalom; Stocchi, Fabrizio

    2015-01-01

    Background. The early detection of wearing-off in Parkinson disease (DEEP) observational study demonstrated that women with Parkinson's disease (PD) carry an increased risk (80.1%) for wearing-off (WO). This post hoc analysis of DEEP study evaluates gender differences on WO and associated phenomena. Methods. Patients on dopaminergic treatment for ≥1 year were included in this multicenter observational cross-sectional study. In a single visit, WO was diagnosed based on neurologist assessment as well as the use of the 19-item wearing-off questionnaire (WOQ-19); WO was defined for scores ≥2. Post hoc analyses were conducted to investigate gender difference for demographic and clinical features with respect to WO. Results. Of 617 patients enrolled, 236 were women and 381 were men. Prevalence of WO was higher among women, according to both neurologists' judgment (61.9% versus 53.8%, P = 0.045) and the WOQ-19 analysis (72.5% versus 64.0%, P = 0.034). In patients with WO (WOQ-19), women experienced ≥1 motor symptom in 72.5% versus 64.0% in men and ≥1 nonmotor symptom in 44.5% versus 36.7%, in men. Conclusions. Our results suggest WO as more common among women, for both motor and nonmotor symptoms. Prospective studies are warranted to investigate this potential gender-effect. PMID:25685848

  17. Rotigotine in Combination with the MAO-B Inhibitor Selegiline in Early Parkinson’s Disease: A Post Hoc Analysis

    PubMed Central

    Giladi, Nir; Asgharnejad, Mahnaz; Bauer, Lars; Grieger, Frank; Boroojerdi, Babak

    2016-01-01

    Background: Monoamine oxidase B (MAO-B) inhibitors and dopamine receptor agonists are common first-line treatment options in early Parkinson’s disease (PD). Objective: To evaluate the efficacy and safety of rotigotine transdermal patch as an add-on therapy to an MAO-B inhibitor in patients with early-PD. Methods: In two Phase III, randomized, double-blind, placebo-controlled studies in early-PD (SP512, SP513), patients were randomized to rotigotine (titrated to optimal dose ≤8 mg/24 h) or placebo, and maintained for 24 (SP512) or 33 (SP513) weeks. Post hoc analyses were performed on pooled data for patients receiving an MAO-B inhibitor (selegiline) at a stable dose at randomization and throughout the studies, with groups defined as “Selegiline+Rotigotine” and “Selegiline+Placebo”. Outcome measures included change from baseline in Unified Parkinson’s Disease Rating Scale (UPDRS) II (activities of daily living), III (motor), UPDRS II+III and responders (patients achieving ≥20%, ≥25% or ≥30% decrease in UPDRS II+III). As post hoc analyses, p-values are exploratory. Results: 130 patients were evaluable for efficacy analyses (“Selegiline+Rotigotine”: 84, “Selegiline+Placebo”: 46). Combined treatment with rotigotine and selegiline improved UPDRS III and UPDRS II+III scores versus selegiline alone (LS-mean [95% CI] treatment difference for UPDRS III: –4.89 [–7.87 to –1.91], p = 0.0015; for UPDRS II+III: –5.76 [–9.71 to –1.82], p = 0.0045). Higher proportion of patients in the “Selegiline+Rotigotine” group were classified as ≥20%, ≥25% or ≥30% responders (all p < 0.001). Combined treatment appeared more effective in patients aged ≤65 years versus > 65 years (although patient numbers in the subgroups were low). Adverse event profile was consistent with the known safety profile of rotigotine. Conclusions: In these post hoc analyses, adjunctive treatment with rotigotine in patients already receiving an

  18. Performance analysis of multi-radio routing protocol in cognitive radio ad hoc networks under different path failure rate

    NASA Astrophysics Data System (ADS)

    Che-Aron, Z.; Abdalla, A. H.; Abdullah, K.; Hassan, W. H.

    2013-12-01

    In recent years, Cognitive Radio (CR) technology has largely attracted significant studies and research. Cognitive Radio Ad Hoc Network (CRAHN) is an emerging self-organized, multi-hop, wireless network which allows unlicensed users to opportunistically access available licensed spectrum bands for data communication under an intelligent and cautious manner. However, in CRAHNs, a lot of failures can easily occur during data transmission caused by PU (Primary User) activity, topology change, node fault, or link degradation. In this paper, an attempt has been made to evaluate the performance of the Multi-Radio Link-Quality Source Routing (MR-LQSR) protocol in CRAHNs under different path failure rate. In the MR-LQSR protocol, the Weighted Cumulative Expected Transmission Time (WCETT) is used as the routing metric. The simulations are carried out using the NS-2 simulator. The protocol performance is evaluated with respect to performance metrics like average throughput, packet loss, average end-to-end delay and average jitter. From the simulation results, it is observed that the number of path failures depends on the PUs number and mobility rate of SUs (Secondary Users). Moreover, the protocol performance is greatly affected when the path failure rate is high, leading to major service outages.

  19. Neuromathematical Trichotomous Mixed Methods Analysis: Using the Neuroscientific Tri-Squared Test Statistical Metric as a Post Hoc Analytic to Determine North Carolina School of Science and Mathematics Leadership Efficacy

    ERIC Educational Resources Information Center

    Osler, James Edward, II; Mason, Letita R.

    2016-01-01

    This study examines the leadership efficacy amongst graduates of The North Carolina School of Science and Mathematics (NCSSM) for the classes of 2000 through 2007 from a neuroscientific and neuromathematic perspective. NCSSM alumni (as the primary unit of analysis) were examined using a novel neuromathematic post hoc method of analysis. This study…

  20. Long-Term Effects of Safinamide on Dyskinesia in Mid- to Late-Stage Parkinson’s Disease: A Post-Hoc Analysis

    PubMed Central

    Cattaneo, Carlo; Ferla, R. La; Bonizzoni, Erminio; Sardina, Marco

    2015-01-01

    Abstract Background: Safinamide is a novel α-aminoamide with dopaminergic and non-dopaminergic properties developed as adjunctive therapy for patients with PD. Results from a 24-month double-blind controlled study suggested that as add-on to levodopa (and other PD medications) the benefits of safinamide on dyskinesia may be related to severity of dyskinesia at baseline. Objective: This post-hoc analysis further characterized the effects of safinamide on dyskinesia in mid- to late-stage PD patients. Methods: Patients were stratified by the presence or absence of dyskinesia at baseline, and by whether or not the dose of levodopa had been changed during the 24-month treatment period. Differences between safinamide and placebo were evaluated using the Wilcoxon rank-sum test. Results: For the overall treated population (with or without baseline dyskinesia), safinamide 100 mg/day significantly improved the dyskinesia rating scale score, compared with placebo, in the subgroup of patients with no change in levodopa dose (p = 0.0488). For patients with baseline dyskinesia, improvements over placebo were also significant (p = 0.0153) in patients with or without changes in levodopa dose, and nearly significant (p = 0.0546) in patients with no change in levodopa dose, suggesting that these improvements were not due to levodopa dose reductions. Conclusions: While no statistically significant difference in mean DRS scores was seen between safinamide and placebo in the original study population, the present post-hoc analysis helps to provide a meaningful interpretation of the long-term effects of safinamide on dyskinesia. These results may be related to safinamide state- and use-dependent inhibition of sodium channels and stimulated glutamate release, and are unlikely due to reduced dopaminergic stimulation. PMID:26406127

  1. The effect of macrobiotic Ma-Pi 2 diet on systemic inflammation in patients with type 2 diabetes: a post hoc analysis of the MADIAB trial

    PubMed Central

    Soare, Andreea; Del Toro, Rossella; Roncella, Elena; Khazrai, Yeganeh Manon; Angeletti, Silvia; Dugo, Laura; Fallucca, Sara; Fontana, Lucia; Altomare, Maria; Formisano, Valeria; Capata, Francesca; Gesuita, Rosaria; Manfrini, Silvia; Fallucca, Francesco; Pianesi, Mario; Pozzilli, Paolo

    2015-01-01

    Introduction Current guidelines for the management of type 2 diabetes (T2D) emphasize diet as essential therapy. However, the effect of diet on systemic inflammation remains unclear. We investigated the effects of consuming a macrobiotic Ma-Pi 2 diet versus a standard recommended diet (control diet) on markers of inflammation in patients with T2D. Methods This was a post hoc analysis of the MADIAB trial, a 21-day randomized controlled trial conducted in 51 patients (25 males and 26 females) with T2D. Patients were randomized 1:1 to the Ma-Pi 2 macrobiotic diet or a control diet based on dietary guidelines for T2D. Biological antioxidant potential of plasma and circulating levels of high-sensitivity C reactive protein, interleukin-6, tumor necrosis factor-α, and insulin-like growth factor-1 were assessed. Results After 21 days on the Ma-Pi 2 or control diet, markers of inflammation were reduced in both groups. The antioxidant potential of plasma improved significantly in the Ma-Pi group. A significant reduction in insulin growth factor-1 was observed in the Ma-Pi group versus control group (p<0.001). Conclusions Findings of this post hoc analysis demonstrated that the Ma-Pi 2 diet is a safe dietary strategy to reduce levels of the markers of insulin resistance and inflammation, compared with baseline values, in the short term. Furthermore, the Ma-Pi 2 diet was superior to the control diet in reducing insulin growth factor-1 and may be beneficial for patients with T2D. Trial registration number Current Controlled Trials ISRCTN10467793. PMID:25852946

  2. Nausea and Vomiting following Balanced Xenon Anesthesia Compared to Sevoflurane: A Post-Hoc Explorative Analysis of a Randomized Controlled Trial

    PubMed Central

    Fahlenkamp, Astrid V.; Stoppe, Christian; Cremer, Jan; Biener, Ingeborg A.; Peters, Dirk; Leuchter, Ricarda; Eisert, Albrecht; Apfel, Christian C.; Rossaint, Rolf; Coburn, Mark

    2016-01-01

    Objective Like other inhalational anesthetics xenon seems to be associated with post-operative nausea and vomiting (PONV). We assessed nausea incidence following balanced xenon anesthesia compared to sevoflurane, and dexamethasone for its prophylaxis in a randomized controlled trial with post-hoc explorative analysis. Methods 220 subjects with elevated PONV risk (Apfel score ≥2) undergoing elective abdominal surgery were randomized to receive xenon or sevoflurane anesthesia and dexamethasone or placebo after written informed consent. 93 subjects in the xenon group and 94 subjects in the sevoflurane group completed the trial. General anesthesia was maintained with 60% xenon or 2.0% sevoflurane. Dexamethasone 4mg or placebo was administered in the first hour. Subjects were analyzed for nausea and vomiting in predefined intervals during a 24h post-anesthesia follow-up. Results Logistic regression, controlled for dexamethasone and anesthesia/dexamethasone interaction, showed a significant risk to develop nausea following xenon anesthesia (OR 2.30, 95% CI 1.02–5.19, p = 0.044). Early-onset nausea incidence was 46% after xenon and 35% after sevoflurane anesthesia (p = 0.138). After xenon, nausea occurred significantly earlier (p = 0.014), was more frequent and rated worse in the beginning. Dexamethasone did not markedly reduce nausea occurrence in both groups. Late-onset nausea showed no considerable difference between the groups. Conclusion In our study setting, xenon anesthesia was associated with an elevated risk to develop nausea in sensitive subjects. Dexamethasone 4mg was not effective preventing nausea in our study. Group size or dosage might have been too small, and change of statistical analysis parameters in the post-hoc evaluation might have further contributed to a limitation of our results. Further trials will be needed to address prophylaxis of xenon-induced nausea. Trial Registration EU Clinical Trials EudraCT-2008-004132-20 ClinicalTrials.gov NCT

  3. Pregabalin versus SSRIs and SNRIs in benzodiazepine-refractory outpatients with generalized anxiety disorder: a post hoc cost-effectiveness analysis in usual medical practice in Spain

    PubMed Central

    De Salas-Cansado, Marina; Olivares, José M; Álvarez, Enrique; Carrasco, Jose L; Barrueta, Andoni; Rejas, Javier

    2012-01-01

    Background Generalized anxiety disorder (GAD) is a prevalent health condition which seriously affects both patient quality of life and the National Health System. The aim of this research was to carry out a post hoc cost-effectiveness analysis of the effect of pregabalin versus selective serotonin reuptake inhibitors (SSRIs)/serotonin norepinephrine reuptake inhibitors (SNRIs) in treated benzodiazepine-refractory outpatients with GAD. Methods This post hoc cost-effectiveness analysis used secondary data extracted from the 6-month cohort, prospective, noninterventional ADAN study, which was conducted to ascertain the cost of illness in GAD subjects diagnosed according to Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition criteria. Benzodiazepine-refractory subjects were those who claimed persistent symptoms of anxiety and showed a suboptimal response (Hamilton Anxiety Rating Scale ≥ 16) to benzodiazepines, alone or in combination, over 6 months. Patients could switch to pregabalin (as monotherapy or addon) or to an SSRI or SNRI, alone or in combination. Effectiveness was expressed as quality-adjusted life years gained, and the perspective was that of the National Health System in the year 2008. A sensitivity analysis was performed using bootstrapping techniques (10,000 resamples were obtained) in order to obtain a cost-effectiveness plane and a corresponding acceptability curve. Results A total of 282 subjects (mean Hamilton Anxiety Rating Scale score 25.8) were identified, comprising 157 in a pregabalin group and 125 in an SSRI/SNRI group. Compared with SSRI/SNRI, pregabalin (average dose 163 mg/day) was associated with higher quality-adjusted life years gained (0.1086 ± 0.0953 versus 0.0967 ± 0.1003, P = 0.334), but increased health care costs (€1014 ± 762 versus €846 ± 620, P = 0.166) and drug costs (€376 ± 252 versus 220 ± 140, P < 0.001), resulting in an incremental cost-effectiveness ratio of €25,304 (95% confidence interval

  4. Telavancin for Acute Bacterial Skin and Skin Structure Infections, a Post Hoc Analysis of the Phase 3 ATLAS Trials in Light of the 2013 FDA Guidance

    PubMed Central

    Pushkin, Richard; Barriere, Steven L.; Corey, G. Ralph; Stryjewski, Martin E.

    2015-01-01

    Two phase 3 ATLAS trials demonstrated noninferiority of telavancin compared with vancomycin for complicated skin and skin structure infections. Data from these trials were retrospectively evaluated according to 2013 U.S. Food and Drug Administration (FDA) guidance on acute bacterial skin and skin structure infections. This post hoc analysis included patients with lesion sizes of ≥75 cm2 and excluded patients with ulcers or burns (updated all-treated population; n = 1,127). Updated day 3 (early) clinical response was defined as a ≥20% reduction in lesion size from baseline and no rescue antibiotic. Updated test-of-cure (TOC) clinical response was defined as a ≥90% reduction in lesion size, no increase in lesion size since day 3, and no requirement for additional antibiotics or significant surgical procedures. Day 3 (early) clinical responses were achieved in 62.6% and 61.0% of patients receiving telavancin and vancomycin, respectively (difference, 1.7%, with a 95% confidence interval [CI] of −4.0% to 7.4%). Updated TOC visit cure rates were similar for telavancin (68.0%) and vancomycin (63.3%), with a difference of 4.8% (95% CI, −0.7% to 10.3%). Adopting current FDA guidance, this analysis corroborates previous noninferiority findings of the ATLAS trials of telavancin compared with vancomycin. PMID:26248356

  5. Treatment of Pulmonary Embolism With Rivaroxaban: Outcomes by Simplified Pulmonary Embolism Severity Index Score from a Post Hoc Analysis of the EINSTEIN PE Study

    PubMed Central

    Fermann, Gregory J; Erkens, Petra M G; Prins, Martin H; Wells, Philip S; Pap, Ákos F; Lensing, Anthonie W A; Kline, Jeffrey

    2015-01-01

    Objectives The objective was to assess adverse outcomes in relation to the simplified Pulmonary Embolism Severity Index (PESI) score in patients treated with rivaroxaban or standard therapy in the phase III EINSTEIN PE study and to evaluate the utility of the simplified PESI score to identify low-risk pulmonary embolism (PE) patients. Methods A post hoc analysis of EINSTEIN PE data was performed to assess the efficacy and safety of rivaroxaban in patients with a range of simplified PESI scores. Recurrent venous thromboembolism, fatal PE, all-cause mortality, and major bleeding were stratified by simplified PESI scores of 0, 1, or ≥2 and according to treatment period at 7, 14, 30, and 90 days and at the end of the full intended treatment period. Results Simplified PESI scores could be calculated in 4,831 of the 4,832 randomized patients; of those, 53.6, 36.7, and 9.7% had PESI scores of 0, 1, and ≥2, respectively. Among patients with simplified PESI scores of 0 or 1, fatal PE, all-cause mortality, and other adverse outcomes were uncommon within the first 7, 14, and 30 days. Patients with simplified PESI scores of ≥2 had more frequent adverse outcomes. Major bleeding was lower in the rivaroxaban group, particularly in those with simplified PESI scores of 1 or ≥2. Conclusions The findings support using risk stratification with the simplified PESI score to identify low-risk patients with PE. PMID:25716463

  6. Chronic effort dyspnea explained by lung function tests and by HRCT and CRX radiographic patterns in COPD: a post-hoc analysis in 51 patients.

    PubMed

    Giuntini, Carlo; Camiciottoli, Gianna; Maluccio, Nazzarena Maria; Mariani, Laura; Lavorini, Federico; Pistolesi, Massimo

    2007-09-01

    This paper is a post-hoc analysis of a previous study performed to investigate the relationship between computerized tomography (CT) and lung function in 51 outpatients with mild-to-moderate COPD. We studied whether changes in lung function and radiographic patterns may help to explain dyspnea, the most disturbing symptom in patients with COPD. The Medical Research Council (MRC) dyspnea scale shows, by univariate analysis, a similar strength of association to CT expiratory lung density and to DL(CO), a functional index of lung parenchymal loss. The MRC dyspnea scale shows a somewhat less strength of association with a small vertical heart on plain chest films. In multivariate analysis, the model with the strongest association to the MRC dyspnea scale (r = 0.76, p < 0.0001) contains 4 explanatory variables (DL(CO), FRC, PaCO(2), and radiographic pattern of pulmonary hypertension). We suggest that diffusing capacity reflects the emphysematous component of hyperinflation, associated by definition with destruction of terminal airspace walls, as distinct from the air trapping component, which is ascribed to airway obstruction and associated with FRC. PaCO(2) mainly reflects the ventilatory components, i.e., ventilatory drive and ventilatory constraints, of pulmonary gas exchange in COPD, while radiographic pattern of pulmonary hypertension likely reflects hypoxic vascular changes, which depend mainly on ventilation/perfusion mismatch and give rise to pulmonary arterial hypertension that may contribute per se to dyspnea. In conclusion, our analysis points out that chronic effort dyspnea variance may account for up to 58% (r(2) = 0.58) by lung function tests and radiographic patterns. Thus, about 42% of the MRC dyspnea variance remains unexplained by this model. On the other hand, dyspnea ascertainment is dependent on subjective behavior and evaluation and in tests is influenced by individual performance and perception. For example in the 6-minute walk test, a similar or

  7. Effects of statins on the progression of cerebral white matter lesion: Post hoc analysis of the ROCAS (Regression of Cerebral Artery Stenosis) study.

    PubMed

    Mok, Vincent C T; Lam, Wynnie W M; Fan, Yu Hua; Wong, Adrian; Ng, Ping Wing; Tsoi, Tak Hon; Yeung, Vincent; Wong, Ka Sing

    2009-05-01

    Arteriosclerotic related cerebral white matter lesion (WML) is associated with increased risk of death, stroke, dementia, depression, gait disturbance, and urinary incontinence. We investigated the effects of statins on WML progression by performing a post hoc analysis on the ROCAS (Regression of Cerebral Artery Stenosis) study, which is a randomized, double-blind, placebo-controlled study evaluating the effects of statins upon asymptomatic middle cerebral artery stenosis progression among stroke-free individuals. Two hundreds and eight randomized subjects were assigned to either placebo (n = 102) or simvastatin 20 mg daily (n = 106) for 2 years. Baseline severity of WML was graded visually into none, mild, and severe. Volume (cm3) of WML was determined quantitatively at baseline and at end of study using a semi-automated method based on MRI. Primary outcome was the change in WML volume over 2 years. After 2 years of follow-up, there was no significant change in WML volume between the active and the placebo group as a whole. However, stratified analysis showed that for those with severe WML at baseline, the median volume increase in the active group (1.9 cm3) was less compared with that in the placebo group (3.0 cm3; P = 0.047). Linear multivariate regression analysis identified that baseline WML volume (beta = 0.63, P < 0.001) and simvastatin treatment (beta = -0.214, P = 0.043) independently predicted change in WML volume. Our findings suggest that statins may delay the progression of cerebral WML only among those who already have severe WML at baseline. PMID:19252811

  8. Delay Analysis of Max-Weight Queue Algorithm for Time-Varying Wireless Ad hoc Networks—Control Theoretical Approach

    NASA Astrophysics Data System (ADS)

    Chen, Junting; Lau, Vincent K. N.

    2013-01-01

    Max weighted queue (MWQ) control policy is a widely used cross-layer control policy that achieves queue stability and a reasonable delay performance. In most of the existing literature, it is assumed that optimal MWQ policy can be obtained instantaneously at every time slot. However, this assumption may be unrealistic in time varying wireless systems, especially when there is no closed-form MWQ solution and iterative algorithms have to be applied to obtain the optimal solution. This paper investigates the convergence behavior and the queue delay performance of the conventional MWQ iterations in which the channel state information (CSI) and queue state information (QSI) are changing in a similar timescale as the algorithm iterations. Our results are established by studying the stochastic stability of an equivalent virtual stochastic dynamic system (VSDS), and an extended Foster-Lyapunov criteria is applied for the stability analysis. We derive a closed form delay bound of the wireless network in terms of the CSI fading rate and the sensitivity of MWQ policy over CSI and QSI. Based on the equivalent VSDS, we propose a novel MWQ iterative algorithm with compensation to improve the tracking performance. We demonstrate that under some mild conditions, the proposed modified MWQ algorithm converges to the optimal MWQ control despite the time-varying CSI and QSI.

  9. Preoperative opioid strength may not affect outcomes of anterior cervical procedures: a post hoc analysis of 2 prospective, randomized trials

    PubMed Central

    Kelly, Michael P.; Anderson, Paul A.; Sasso, Rick C.; Riew, K. Daniel

    2015-01-01

    Object The aim of this study is to evaluate the relationship between preoperative opioid strength and outcomes of anterior cervical decompressive surgery. Methods A retrospective cohort of 1004 patients enrolled in 1 of 2 investigational device exemption studies comparing cervical total disc arthroplasty (TDA) and anterior cervical discectomy and fusion (ACDF) for single-level cervical disease causing radiculopathy or myelopathy was selected. At a preoperative visit, opioid use data, Neck Disability Index (NDI) scores, 36-ltem Short-Form Health Survey (SF-36) scores, and numeric rating scale scores for neck and arm pain were collected. Patients were divided into strong (oxycodone/morphine/meperidine), weak (codeine/propoxyphene/ hydrocodone), and opioid-naïve groups. Preoperative and postoperative (24 months) outcomes scores were compared within and between groups using the paired t-test and ANCOVA, respectively. Results Patients were categorized as follows: 226 strong, 762 weak, and 16 opioid naïve. The strong and weak groups were similar with respect to age, sex, race, marital status, education level, Worker's Compensation status, litigation status, and alcohol use. At 24-month follow-up, no differences in change in arm or neck pain scores (arm: strong –52.3, weak –50.6, naïve –54.0, p = 0.244; neck: strong –52.7, weak –50.8, naïve –44.6, p = 0.355); NDI scores (strong –36.0, weak –33.3, naïve –32.3, p = 0.181); or SF-36 Physical Component Summary scores (strong: 14.1, weak 13.3, naïve 21.7, p = 0.317) were present. Using a 15-point improvement in NDI to determine success, the authors found no between-groups difference in success rates (strong 80.6%, weak 82.7%, naïve 73.3%, p = 0.134). No difference existed between treatment arms (TDA vs ACDF) for any outcome at any time point. Conclusions Preoperative opioid strength did not adversely affect outcomes in this analysis. Careful patient selection can yield good results in this patient

  10. Effects of calcium channel blocker-based combinations on intra-individual blood pressure variability: post hoc analysis of the COPE trial.

    PubMed

    Umemoto, Seiji; Ogihara, Toshio; Matsuzaki, Masunori; Rakugi, Hiromi; Ohashi, Yasuo; Saruta, Takao

    2016-01-01

    Visit-to-visit blood pressure (BP) variability is an important predictor of stroke. However, which antihypertensive drug combination is better at reducing visit-to-visit BP variability and therefore at reducing stroke incidence remains uncertain. We have previously reported that the dihydropyridine calcium channel blocker benidipine combined with a β-blocker appeared to be less beneficial in reducing the risk of stroke than a combination of benidipine and thiazide. Here, we further compare the visit-to-visit BP variability among three benidipine-based regimens, namely angiotensin receptor blocker (ARB), β-blocker and thiazide combinations. The present post hoc analysis included 2983 patients without cardiovascular events or death during the first 18 months after randomization. We compared the BP variability (defined as the s.d. and the coefficient of variation (CV)), maximum systolic BP (SBP) and diastolic BP (DBP) of the clinic mean on-treatment BPs obtained at 6-month intervals, starting 6 months after the treatment initiation, among the 3 treatments (ARB, n=1026; β-blocker, n=966; thiazide, n=991). During the first 6-36 months after randomization, both the s.d. and CV-BPs were lower in the benidipine-thiazide group than in the benidipine-β-blocker group (s.d.-SBP, P=0.019; s.d.-DBP, P=0.030; CV-SBP, P=0.012; CV-DBP, P=0.022). The s.d. and CV in the ARB group did not reach statistical significance compared with the other two groups. The maximum BPs did not differ among the three treatments. These findings suggest that the benidipine-thiazide combination may reduce visit-to-visit BP variability more than the benidipine-β-blocker combination. PMID:26490089

  11. Effect of lurasidone dose on cognition in patients with schizophrenia: post-hoc analysis of a long-term, double-blind continuation study.

    PubMed

    Harvey, Philip D; Siu, Cynthia O; Ogasa, Masaaki; Loebel, Antony

    2015-08-01

    We previously reported that treatment with 160mg/d of lurasidone improved cognitive performance in a manner superior to placebo, quetiapine XR 600mg/d, and lurasidone 80mg/d, based on a 6-week randomized trial of patients with an acute exacerbation of schizophrenia. The objective of this post-hoc analysis was to explore the cognitive and functional performance of patients whose final doses of lurasidone were 40/80mg/d, 120mg/d, and 160mg/d compared to quetiapine XR 200-800mg/d (QXR) during a 6-month, double-blind continuation study that followed a short-term trial. Subjects who received final doses of lurasidone 120mg/d (n=77) and 160mg/d (n=49) showed significantly greater improvement in overall cognitive performance compared to QXR (n=85) at week 32 (month 6 of the extension study), while those on last doses of 40/80mg/d (n=25) showed a trend towards significance at week 32. Mean changes in neurocognitive composite z-score from pre-treatment baseline were significant for the 3 lurasidone final dose groups at both weeks 19 and 32, with composite change scores of z=1.53, z=1.43, and z=1.34 for the lurasidone 40/80mg/d, 120mg/d, and 160mg/d, respectively, at week 32. In contrast, the composite change score was not statistically significant in the overall quetiapine group (z=0.46), with none of the individual quetiapine doses showing any significant improvement. Functional capacity scores improved in all treatment groups. Our findings indicate improved cognitive performance in patients treated with each of the flexible doses of lurasidone 40-160mg/d, compared to quetiapine XR 200-800mg/d. All doses of lurasidone were superior to all doses of quetiapine for cognitive performance. PMID:26117157

  12. Post-hoc analysis showing better clinical response with the loading dose of certolizumab pegol in Japanese patients with active rheumatoid arthritis

    PubMed Central

    Takeuchi, Tsutomu; Yamamoto, Kazuhiko; Yamanaka, Hisashi; Ishiguro, Naoki; Tanaka, Yoshiya; Eguchi, Katsumi; Watanabe, Akira; Origasa, Hideki; Kobayashi, Mariko; Shoji, Toshiharu; Togo, Osamu; Miyasaka, Nobuyuki; Koike, Takao

    2016-01-01

    Abstract Objectives: To compare the efficacy and safety of certolizumab pegol (CZP) with and without loading dose (LD) in a post-hoc analysis of two Japanese clinical studies. Methods: Data from the double-blind trials (DBT) J-RAPID and HIKARI, and their open-label extension (OLE) studies, were used. Patients randomized to CZP 200 mg every 2 weeks (Q2W) groups starting with LD (400 mg Weeks 0/2/4; LD group; J-RAPID: n = 82, HIKARI: n = 116) and patients randomized to placebo groups who subsequently started CZP Q2W without LD in the OLEs (No-LD group; J-RAPID: n = 61, HIKARI: n = 99) were analyzed. Efficacy and pharmacokinetics were assessed during 24 weeks. Adverse events were reported from all studies. Results: In both trials, the LD groups showed more rapid initial ACR20/50/70 kinetics, and maintained higher ACR50/70 responses until 24 weeks, compared with the No-LD groups. Anti-CZP antibody development was less frequent in the LD groups (J-RAPID: 1.2% versus 4.9%; HIKARI: 17.2% versus 27.3%). Similar safety profiles were reported between LD and No-LD groups (any AEs: 281.8 versus 315.7 [J-RAPID], 282.6 versus 321.3 [HIKARI] [incidence rate/100 patient-years]). Conclusions: Despite limitations, including comparing DBT and OLE studies, these results suggest that a CZP LD improves clinical response in active rheumatoid arthritis without altering the safety profile. PMID:26472043

  13. Robust message routing for mobile (wireless) ad hoc networks.

    SciTech Connect

    Goldsby, Michael E.; Johnson, Michael M.; Kilman, Dominique Marie; Bierbaum, Neal Robert; Chen, Helen Y.; Ammerlahn, Heidi R.; Tsang, Rose P.; Nicol, David M.

    2004-01-01

    This report describes the results of research targeting improvements in the robustness of message transport in wireless ad hoc networks. The first section of the report provides an analysis of throughput and latency in the wireless medium access control (MAC) layer and relates the analysis to the commonly used 802.11 protocol. The second section describes enhancements made to several existing models of wireless MAC and ad hoc routing protocols; the models were used in support of the work described in the following section. The third section of the report presents a lightweight transport layer protocol that is superior to TCP for use in wireless networks. In addition, it introduces techniques that improve the performance of any ad hoc source routing protocol. The fourth section presents a novel, highly scalable ad hoc routing protocol that is based on geographic principles but requires no localization hardware.

  14. A Post Hoc Analysis of the Effect of Weight on Efficacy in Depressed Patients Treated With Desvenlafaxine 50 mg/d and 100 mg/d

    PubMed Central

    Fayyad, Rana S.; Guico-Pabia, Christine J.; Boucher, Matthieu

    2015-01-01

    Objective: To assess the effect of baseline body mass index (BMI) on efficacy and weight change in adults with major depressive disorder (MDD) treated with desvenlafaxine or placebo in a pooled, post hoc analysis. Method: Adults with MDD were randomly assigned to placebo or desvenlafaxine (50 mg or 100 mg) in 8 short-term, double-blind studies and 1 longer-term randomized withdrawal study (the studies were published between 2007 and 2013). Change from baseline in 17-item Hamilton Depression Rating Scale (HDRS-17) total score at week 8 was analyzed in normal (BMI ≤ 25 kg/m2), overweight (25 kg/m2 < BMI ≤ 30 kg/m2), and obese (BMI > 30 kg/m2) subgroups using analysis of covariance (ANCOVA). Weight change was analyzed in BMI subgroups using ANCOVA and a mixed-effects model for repeated measures. Results: Desvenlafaxine 50 mg/d or 100 mg/d improved HDRS-17 scores significantly from baseline to week 8 (last observation carried forward) versus placebo in all BMI subgroups (normal: n = 1,122; overweight: n = 960; obese: n = 1,302; all P ≤ .0027); improvement was greatest in normal BMI patients. There was a statistically significant decrease in weight (< 1 kg) with short-term desvenlafaxine 50 mg/d and 100 mg/d versus placebo in all BMI subgroups (all P < .0001). In the randomized withdrawal study (n = 548), no statistically significant difference in weight was observed for desvenlafaxine versus placebo in any BMI subgroup. Baseline BMI predicted weight change in short-term and longer-term desvenlafaxine treatment. Conclusions: Desvenlafaxine significantly improved symptoms of depression versus placebo regardless of baseline BMI. In all BMI subgroups, desvenlafaxine was associated with statistically significant weight loss (< 1 kg) versus placebo over 8 weeks, but no significant differences longer term. Trial Registration: ClinicalTrials.gov identifiers: NCT00072774, NCT00277823, NCT00300378, NCT00384033, NCT00798707, NCT00863798, NCT01121484, NCT00824291, NCT

  15. History of Depressive and Anxiety Disorders and Paroxetine Response in Patients With Irritable Bowel Syndrome: Post Hoc Analysis From a Placebo-Controlled Study

    PubMed Central

    Marks, David M.; Han, Changsu; Krulewicz, Stan; Pae, Chi-Un; Peindl, Kathleen; Patkar, Ashwin A.; Masand, Prakash S.

    2008-01-01

    Objective: Although irritable bowel syndrome (IBS) is highly comorbid with depressive and anxiety disorders, information on the clinical implications of this comorbidity is limited. We investigated whether a history of depressive and/or anxiety disorders was associated with response to treatment in a double-blind, randomized, placebo-controlled trial of paroxetine controlled release (CR) in IBS. Method: Seventy-two IBS subjects (diagnosed using Rome II criteria) were recruited from August 2003 to November 2005 and randomly assigned to receive flexibly dosed paroxetine CR (dose, 12.5–50 mg/day) or placebo for 12 weeks. The Mini-International Neuropsychiatric Interview (MINI-Plus version) was used to ascertain current (exclusionary) or past diagnoses of depressive and anxiety disorders. Subjective depression, anxiety, and stress were assessed at entry and throughout the trial using the Beck Depression Inventory (BDI), Beck Anxiety Inventory (BAI), and Perceived Stress Scale (PSS). Severity of IBS symptoms was determined by the Composite Pain Score (CPS), administered via Interactive Voice Response System, and the Clinical Global Impressions scale (CGI). The primary outcome was treatment response defined as ≥ 25% reduction in CPS from randomization to end of treatment. A post hoc analysis (multivariate logistic regression) was done to evaluate whether a history of depressive and/or anxiety disorder was associated with response to medication. Results: Baseline demographic and clinical characteristics (CPS, BDI, BAI, PSS, CGI scores) were similar between groups (history of depressive/anxiety disorder vs. no history). In multivariate logistic regression analysis, treatment response was not predicted by history of depressive and/or anxiety disorder (OR = 0.58, CI = 0.29 to 1.68, p = .32) or drug status (paroxetine CR vs. placebo) (OR = 1.26, CI = 0.68 to 3.21, p = .19). Drug status was significantly associated with the secondary outcome variable of treatment response

  16. Efficacy and tolerability of adjunct perampanel based on number of antiepileptic drugs at baseline and baseline predictors of efficacy: A phase III post-hoc analysis.

    PubMed

    Glauser, Tracy; Laurenza, Antonio; Yang, Haichen; Williams, Betsy; Ma, Tony; Fain, Randi

    2016-01-01

    Perampanel is a selective, noncompetitive AMPA receptor antagonist with demonstrated efficacy and tolerability in partial seizures in patients aged ≥ 12 years in Phase III studies. Post-hoc analysis of these studies was conducted to determine the efficacy and tolerability of perampanel based on the number of concomitant antiepileptic drugs (AEDs) at baseline, as well as to examine which baseline characteristics, if any, were predictors of efficacy. Efficacy parameters were based on the number of baseline AEDs, and logistic regression analyses were used to evaluate the association of demographic and baseline clinical factors with probability of ≥ 50% reduction in seizure frequency. Patients on 1 AED at baseline were significantly more likely to have reduced seizure frequency (P<0.02) and improved 50% responder rate (P<0.02) than patients on 3 AEDs at baseline. Secondarily generalized seizures at baseline, unknown etiology, and use of concomitant non-inducer AEDs were also established as positive predictors of efficacy (50% responder rate; P<0.01). Patients with more AEDs at baseline were associated with greater use of inducers (P<0.01), which may result in decreased exposure of perampanel in these patients and lower efficacy. Patients with 1 AED at baseline had a significantly shorter time since diagnosis compared with patients in the 3 (P<0.01) AEDs group, as well as a lower median seizure frequency at baseline compared to patients on 3 AEDs (P<0.05), suggesting that the reduced efficacy of perampanel with 3 AEDs may also be associated with the greater severity of seizures in the patient groups. The incidence of adverse events in perampanel-treated patients was similar regardless of the number of AEDs at baseline. Greater efficacy is predicted for patients receiving fewer concomitant AEDs when starting perampanel, as well as for those receiving concomitant treatment with AEDs that are not CYP3A4 enzyme-inducers, compared to patients treated with multiple

  17. Differences in glycemic control across world regions: a post-hoc analysis in patients with type 2 diabetes mellitus on dual antidiabetes drug therapy

    PubMed Central

    Brath, H; Paldánius, P M; Bader, G; Kolaczynski, W M; Nilsson, P M

    2016-01-01

    Objective: This post-hoc analysis of the EDGE (Effectiveness of Diabetes control with vildaGliptin and vildagliptin/mEtformin) study assessed inter-regional differences in baseline characteristics and response to treatment intensification with dual oral antidiabetes drugs (OADs) in patients with type 2 diabetes mellitus (T2DM). Methods: Patients with T2DM inadequately controlled with first-line monotherapy were assigned to receive a dipeptidyl peptidase-4 (DPP-4) inhibitor, vildagliptin, or comparator OADs as add-on dual therapy. The primary effectiveness end point (PEP) was achieving glycated hemoglobin (HbA1c) reduction >0.3% without hypoglycemia, peripheral edema, discontinuation owing to gastrointestinal events or weight gain ⩾5% at 12 months. The secondary effectiveness end point (SEP) was achieving HbA1c of <7% without hypoglycemia or weight gain ⩾3% at 12 months. Results: Baseline characteristics of patients (N=43 791), including mean HbA1c (8.2%), varied across regions. Baseline age (62.3 years) and T2DM duration (6.3 years) were greater in patients from Europe than those from India and the Middle East (age: 51.8 and 52.1 years; T2DM duration: 4.3 and 4.2 years, respectively). The probability of achieving PEP with dual therapy was higher in India (odds ratio (OR): 1.5), Latin America (OR: 1.2) and Middle East (OR: 2.0) than in Europe (OR: 0.8) and East Asia (OR: 0.3). Achievement of SEP in patients receiving dual therapy was greater in Latin America (OR: 1.7) and Middle East (OR: 1.7). Vildagliptin add-on therapy allowed more patients to achieve SEP across regions. Women aged ⩾45 years less often attained glycemic target (HbA1c<7%) without significant weight gain ⩾5% compared with women aged <45 years (OR: 0.876, 95% confidence interval: 0.774, 0.992; P=0.037). Conclusions: Baseline HbA1c and T2DM duration differed considerably across all regions. Treatment intensification with second OAD, particularly with a DPP-4 inhibitor vildagliptin, resulted

  18. The PREVAIL trial of enzalutamide in men with chemotherapy-naïve, metastatic castration-resistant prostate cancer: Post hoc analysis of Korean patients

    PubMed Central

    Theeuwes, Ad; Kwon, Dong Deuk; Choi, Young Deuk; Chung, Byung Ha; Lee, Hyun Moo; Lee, Kang Hyun; Lee, Sang Eun

    2016-01-01

    Purpose This post hoc analysis evaluated treatment effects, safety, and pharmacokinetics of enzalutamide in Korean patients in the phase 3, double-blind, placebo-controlled PREVAIL trial. Materials and Methods Asymptomatic or mildly symptomatic chemotherapy-naive men with metastatic castration-resistant prostate cancer that progressed on androgen deprivation therapy received 160 mg/d oral enzalutamide or placebo (1:1) until death or discontinuation due to radiographic progression or skeletal-related event and initiation of subsequent therapy. Coprimary end points were centrally assessed radiographic progression-free survival (rPFS) and overall survival (OS). Secondary end points included investigator-assessed rPFS, time to initiation of chemotherapy, time to prostate-specific antigen (PSA) progression, PSA response (≥50% decline), and time to skeletal-related event. Results Of 1,717 total patients, 78 patients were enrolled in Korea (enzalutamide, n=40; placebo, n=38). Hazard ratios (95% confidence interval) for enzalutamide versus placebo were 0.23 (0.02–2.24) for centrally assessed rPFS, 0.77 (0.28–2.15) for OS, 0.21 (0.08–0.51) for time to chemotherapy, and 0.31 (0.17–0.56) for time to PSA progression. A PSA response was observed in 70.0% of enzalutamide-treated and 10.5% of placebo-treated Korean patients. Adverse events of grade ≥3 occurred in 33% of enzalutamide-treated and 11% of placebo-treated Korean patients, with median treatment durations of 13.0 and 5.1 months, respectively. At 13 weeks, the plasma concentration of enzalutamide plus N-desmethyl enzalutamide was similar in Korean and non-Korean patients (geometric mean ratio, 1.04; 90% confidence interval, 0.97–1.10). Conclusions In Korean patients, treatment effects and safety of enzalutamide were consistent with those observed in the overall PREVAIL study population (ClinicalTrials.gov Identifier: NCT01212991). PMID:27195316

  19. Global Coverage from Ad-Hoc Constellations in Rideshare Orbits

    NASA Technical Reports Server (NTRS)

    Ellis, Armin; Mercury, Michael; Brown, Shannon

    2012-01-01

    A promising area of small satellite development is in providing higher temporal resolution than larger satellites. Traditional constellations have required specific orbits and dedicated launch vehicles. In this paper we discuss an alternative architecture in which the individual elements of the constellation are launched as rideshare opportunities. We compare the coverage of such an ad-hoc constellation with more traditional constellations. Coverage analysis is based on actual historical data from rideshare opportunities. Our analysis includes ground coverage and temporal revisits for Polar, Tropics, Temperate, and Global regions, comparing ad-hoc and Walker constellation.

  20. Effect of smoking reduction and cessation on the plasma levels of the oxidative stress biomarker glutathione--Post-hoc analysis of data from a smoking cessation trial.

    PubMed

    Mons, Ute; Muscat, Joshua E; Modesto, Jennifer; Richie, John P; Brenner, Hermann

    2016-02-01

    Cigarette smoke contains high concentrations of free radical components that induce oxidative stress. Smoking-induced oxidative stress is thought to contribute to chronic obstructive pulmonary disease, cardiovascular disease and lung cancer through degenerative processes in the lung and other tissues. It is uncertain however whether smoking cessation lowers the burden of oxidative stress. We used data from a randomized controlled cessation trial of 434 current smokers for a post-hoc examination of the effects of smoking cessation on blood plasma levels of total glutathione (tGSH), the most abundant endogenous antioxidant in cells, and total cysteine (tCys), an amino acid and constituent of glutathione. Smoking status was validated based on serum cotinine levels. Multivariate linear mixed models were fitted to examine the association of smoking cessation and change in cigarette consumption with tGSH and tCys. After 12 months follow-up, quitters (n=55) had significantly increased levels of tGSH compared to subjects who continued to smoke (P<0.01). No significant change in tGSH was found for subjects who continued to smoke but reduced their intensity of smoking. No significant effect of smoking cessation or reduction was observed on levels of tCys. These results suggest that smoking cessation but not smoking reduction reduces levels of oxidative stress. PMID:26708755

  1. Estimating HIV Incidence during Pregnancy and Knowledge of Prevention of Mother-to-Child Transmission with an Ad Hoc Analysis of Potential Cofactors

    PubMed Central

    Egbe, Thomas Obinchemti; Tazinya, Rose-Mary Asong; Halle-Ekane, Gregory Edie; Egbe, Eta-Nkongho; Achidi, Eric Akum

    2016-01-01

    Background. We determined the incidence of HIV seroconversion during the second and third trimesters of pregnancy and ad hoc potential cofactors associated with HIV seroconversion after having an HIV-negative result antenatally. We also studied knowledge of PMTCT among pregnant women in seven health facilities in Fako Division, South West Region, Cameroon. Method. During the period between September 12 and December 4, 2011, we recruited a cohort of 477 HIV-negative pregnant women by cluster sampling. Data collection was with a pretested interviewer-administered questionnaire. Sociodemographic information, knowledge of PMTCT, and methods of HIV prevention were obtained from the study population and we did Voluntary Counselling and Testing (VCT) for HIV. Results. The incidence rate of HIV seroconversion during pregnancy was 6.8/100 woman-years. Ninety percent of the participants did not use condoms throughout pregnancy but had a good knowledge of PMTCT of HIV. Only 31.9% of participants knew their HIV status before the booking visit and 33% did not know the HIV status of their partners. Conclusion. The incidence rate of HIV seroconversion in the Fako Division, Cameroon, was 6.8/100 woman-years. No risk factors associated with HIV seroconversion were identified among the study participants because of lack of power to do so. PMID:27127653

  2. Patient Background Factors Affecting the Therapeutic Outcomes in Response to Eszopiclone in Adult Patients with Chronic Insomnia: A Post Hoc Analysis of a Double-Blind Phase III Study in Japan

    PubMed Central

    Inoue, Yuichi; Kamijo, Atsushi; Nagai, Reiko

    2015-01-01

    Study Objective: To identify whether baseline demographic factors or subjective sleep variables are associated with the outcomes following treatment with eszopiclone using data from a recent randomized controlled trial of 78 Japanese subjects with insomnia who were treated with 2 mg eszopiclone per day. Methods: We performed a post hoc analysis of factors including sleep latency (SL), wake time after sleep onset (WASO) (both assessed via sleep diaries), and several demographic variables. Subjects with a SL or WASO > 30 min at baseline and with evaluable SL/WASO data at Week 4 were included in SL and WASO remitter analyses, respectively; those with a SL or WASO ≤ 30 min at Week 4 were defined as SL or WASO remitters, respectively. Threshold baseline SL and WASO values for identification of remitters were determined. Results: No relationships between subjectively assessed therapeutic outcomes and demographic factors were identified. Patients with shorter SL and lower WASO values at baseline showed better outcomes following treatment with eszopiclone in terms of SL and WASO changes, respectively. Baseline SL of 75 min and baseline WASO of 80 min were selected as arbitrary cutoff values for determination of SL and WASO remitters/non-remitters, respectively. Conclusions: These findings may help clinicians to predict their patients' outcomes in response to standard doses of eszopiclone in clinical practice. Citation: Inoue Y, Kamijo A, Nagai R. Patient background factors affecting the therapeutic outcomes in response to eszopiclone in adult patients with chronic insomnia: a post hoc analysis of a double-blind phase III study in Japan. J Clin Sleep Med 2015;11(10):1171–1178. PMID:26094929

  3. Anti-hypertensive drug treatment of patients with and the metabolic syndrome and obesity: a review of evidence, meta-analysis, post hoc and guidelines publications.

    PubMed

    Owen, Jonathan G; Reisin, Efrain

    2015-06-01

    Epidemiological studies have shown an increasing prevalence of obesity and the metabolic syndrome worldwide. Lifestyle modifications that include dietary changes, weight reduction, and exercise are the cornerstones in the treatment of this pathology. However, adherence to this approach often meets with failure in clinical practice; therefore, drug therapy should not be delayed. The ideal pharmacological antihypertensive regimen should target the underlying mechanisms involved in this syndrome, including sympathetic activation, increased renal tubular sodium reabsorption, and overexpression of the renin-angiotensin-aldosterone system by the adipocyte. Few prospective trials have been conducted in the search of the ideal antihypertensive regimen in patients with obesity and the metabolic syndrome. We summarize previously published ad hoc studies, prospective studies, and guideline publications regarding the treatment of hypertension in patients with obesity and the metabolic syndrome. We conclude that the optimal antihypertensive drug therapy in these patients has not been defined. Though caution exists regarding the use of thiazide diuretics due to potential metabolic derangements, there is insufficient data to show worsened cardiovascular or renal outcomes in patients treated with these drugs. In regard to beta blockers, the risk of accelerating conversion to diabetes and worsening of inflammatory mediators described in patients treated with traditional beta blockers appears much less pronounced or absent when using the vasodilating beta blockers. Renin-angiotensin-aldosterone system (RAAS) inhibition with an ACE or an ARB and treatment with calcium channel blockers appears safe and well tolerated in obesity-related hypertension and in patients with metabolic syndrome. Future prospective pharmacological studies in this population are needed. PMID:25916862

  4. Research of Ad Hoc Networks Access Algorithm

    NASA Astrophysics Data System (ADS)

    Xiang, Ma

    With the continuous development of mobile communication technology, Ad Hoc access network has become a hot research, Ad Hoc access network nodes can be used to expand capacity of multi-hop communication range of mobile communication system, even business adjacent to the community, improve edge data rates. When the ad hoc network is the access network of the internet, the gateway discovery protocol is very important to choose the most appropriate gateway to guarantee the connectivity between ad hoc network and IP based fixed networks. The paper proposes a QoS gateway discovery protocol which uses the time delay and stable route to the gateway selection conditions. And according to the gateway discovery protocol, it also proposes a fast handover scheme which can decrease the handover time and improve the handover efficiency.

  5. Cytoarchitecture of the human lateral occipital cortex: mapping of two extrastriate areas hOc4la and hOc4lp.

    PubMed

    Malikovic, Aleksandar; Amunts, Katrin; Schleicher, Axel; Mohlberg, Hartmut; Kujovic, Milenko; Palomero-Gallagher, Nicola; Eickhoff, Simon B; Zilles, Karl

    2016-05-01

    The microstructural correlates of the functional segregation of the human lateral occipital cortex are largely unknown. Therefore, we analyzed the cytoarchitecture of this region in ten human post-mortem brains using an observer-independent and statistically testable parcellation method to define the position and extent of areas in the lateral occipital cortex. Two new cytoarchitectonic areas were found: an anterior area hOc4la and a posterior area hOc4lp. hOc4la was located behind the anterior occipital sulcus in rostral and ventral portions of this region where it occupies the anterior third of the middle and inferior lateral occipital gyri. hOc4lp was found in caudal and dorsal portions of this region where it extends along the superior and middle lateral occipital gyri. The cytoarchitectonic areas were registered to 3D reconstructions of the corresponding brains, which were subsequently spatially normalized to the Montreal Neurological Institute reference space. Continuous probabilistic maps of both areas based on the analysis of ten brains were generated to characterize their inter-subject variability in location and size. The maps of hOc4la and hOc4lp were then used as seeds for meta-analytic connectivity modeling and quantitative functional decoding to identify their co-activation patterns and assignment to functional domains. Convergent evidence from their location, topography, size, functional domains and connectivity indicates that hOc4la and hOc4lp are the potential anatomical correlates of the functionally defined lateral occipital areas LO-1 and LO-2. PMID:25687261

  6. Physicians Experience with and Expectations of the Safety and Tolerability of WHO-Step III Opioids for Chronic (Low) Back Pain: Post Hoc Analysis of Data from a German Cross-Sectional Physician Survey

    PubMed Central

    Ueberall, Michael A.; Eberhardt, Alice; Mueller-Schwefe, Gerhard H. H.

    2015-01-01

    Objective. To describe physicians' daily life experience with WHO-step III opioids in the treatment of chronic (low) back pain (CLBP). Methods. Post hoc analysis of data from a cross-sectional online survey with 4.283 Germany physicians. Results. With a reported median use in 17% of affected patients, WHO-step III opioids play a minor role in treatment of CLBP in daily practice associated with a broad spectrum of positive and negative effects. If prescribed, potent opioids were reported to show clinically relevant effects (such as ≥50% pain relief) in approximately 3 of 4 patients (median 72%). Analgesic effects reported are frequently related with adverse events (AEs). Only 20% of patients were reported to remain free of any AE. Most frequently reported AE was constipation (50%), also graded highest for AE-related daily life restrictions (median 46%). Specific AE countermeasures were reported to be necessary in approximately half of patients (median 45%); nevertheless AE-related premature discontinuation rates reported were high (median 22%). Fentanyl/morphine were the most/least prevalently prescribed potent opioids mentioned (median 20 versus 8%). Conclusion. Overall, use of WHO-step III opioids for CLBP is low. AEs, especially constipation, are commonly reported and interfere significantly with analgesic effects in daily practice. Nevertheless, beneficial effects outweigh related AEs in most patients with CLBP. PMID:26568890

  7. Shuttle-run synchronization in mobile ad hoc networks

    NASA Astrophysics Data System (ADS)

    Ma, Sheng-Fei; Bi, Hong-Jie; Zou, Yong; Liu, Zong-Hua; Guan, Shu-Guang

    2015-06-01

    In this work, we study the collective dynamics of phase oscillators in a mobile ad hoc network whose topology changes dynamically. As the network size or the communication radius of individual oscillators increases, the topology of the ad hoc network first undergoes percolation, forming a giant cluster, and then gradually achieves global connectivity. It is shown that oscillator mobility generally enhances the coherence in such networks. Interestingly, we find a new type of phase synchronization/clustering, in which the phases of the oscillators are distributed in a certain narrow range, while the instantaneous frequencies change signs frequently, leading to shuttle-run-like motion of the oscillators in phase space. We conduct a theoretical analysis to explain the mechanism of this synchronization and obtain the critical transition point.

  8. Distributed Reinforcement Learning Approach for Vehicular Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Wu, Celimuge; Kumekawa, Kazuya; Kato, Toshihiko

    In Vehicular Ad hoc Networks (VANETs), general purpose ad hoc routing protocols such as AODV cannot work efficiently due to the frequent changes in network topology caused by vehicle movement. This paper proposes a VANET routing protocol QLAODV (Q-Learning AODV) which suits unicast applications in high mobility scenarios. QLAODV is a distributed reinforcement learning routing protocol, which uses a Q-Learning algorithm to infer network state information and uses unicast control packets to check the path availability in a real time manner in order to allow Q-Learning to work efficiently in a highly dynamic network environment. QLAODV is favored by its dynamic route change mechanism, which makes it capable of reacting quickly to network topology changes. We present an analysis of the performance of QLAODV by simulation using different mobility models. The simulation results show that QLAODV can efficiently handle unicast applications in VANETs.

  9. The relationship, structure and profiles of schizophrenia measurements: a post-hoc analysis of the baseline measures from a randomized clinical trial

    PubMed Central

    2011-01-01

    Background To fully assess the various dimensions affected by schizophrenia, clinical trials often include multiple scales measuring various symptom profiles, cognition, quality of life, subjective well-being, and functional impairment. In this exploratory study, we characterized the relationships among six clinical, functional, cognitive, and quality-of-life measures, identifying a parsimonious set of measurements. Methods We used baseline data from a randomized, multicenter study of patients diagnosed with schizophrenia, schizoaffective disorder, or schizophreniform disorder who were experiencing an acute symptom exacerbation (n = 628) to examine the relationship among several outcome measures. These measures included the Positive and Negative Syndrome Scale (PANSS), Montgomery-Asberg Depression Rating Scale (MADRS), Brief Assessment of Cognition in Schizophrenia Symbol Coding Test, Subjective Well-being Under Neuroleptics Scale Short Form (SWN-K), Schizophrenia Objective Functioning Instrument (SOFI), and Quality of Life Scale (QLS). Three analytic approaches were used: 1) path analysis; 2) factor analysis; and 3) categorical latent variable analysis. In the optimal path model, the SWN-K was selected as the final outcome, while the SOFI mediated the effect of the exogenous variables (PANSS, MADRS) on the QLS. Results The overall model explained 47% of variance in QLS and 17% of the variance in SOFI, but only 15% in SWN-K. Factor analysis suggested four factors: "Functioning," "Daily Living," "Depression," and "Psychopathology." A strong positive correlation was observed between the SOFI and QLS (r = 0.669), and both the QLS and SOFI loaded on the "Functioning" factor, suggesting redundancy between these scales. The measurement profiles from the categorical latent variable analysis showed significant variation in functioning and quality of life despite similar levels of psychopathology. Conclusions Researchers should consider collecting PANSS, SOFI, and SWN-K in

  10. Ad Hoc Access Gateway Selection Algorithm

    NASA Astrophysics Data System (ADS)

    Jie, Liu

    With the continuous development of mobile communication technology, Ad Hoc access network has become a hot research, Ad Hoc access network nodes can be used to expand capacity of multi-hop communication range of mobile communication system, even business adjacent to the community, improve edge data rates. For mobile nodes in Ad Hoc network to internet, internet communications in the peer nodes must be achieved through the gateway. Therefore, the key Ad Hoc Access Networks will focus on the discovery gateway, as well as gateway selection in the case of multi-gateway and handover problems between different gateways. This paper considers the mobile node and the gateway, based on the average number of hops from an average access time and the stability of routes, improved gateway selection algorithm were proposed. An improved gateway selection algorithm, which mainly considers the algorithm can improve the access time of Ad Hoc nodes and the continuity of communication between the gateways, were proposed. This can improve the quality of communication across the network.

  11. Pooled post hoc analysis of population pharmacokinetics of oxycodone and acetaminophen following a single oral dose of biphasic immediate-release/extended-release oxycodone/acetaminophen tablets

    PubMed Central

    Franke, Ryan M; Morton, Terri; Devarakonda, Krishna

    2015-01-01

    This analysis evaluated the single-dose population pharmacokinetics (PK) of biphasic immediate-release (IR)/extended-release (ER) oxycodone (OC)/acetaminophen (APAP) 7.5/325 mg tablets administered under fasted conditions and the effects of a meal on their single-dose population PK. Data were pooled from four randomized, single-dose crossover trials enrolling healthy adult (18–55 years old) participants (three trials) and nondependent recreational users of prescription opioids (one trial) with a body weight of ≥59 kg. Participants received IR/ER OC/APAP 7.5/325 mg tablets in single doses of 7.5/325 mg (one tablet), 15/650 mg (two tablets), or 30/1,300 mg (four tablets) under fasted or fed conditions. Six variables were examined: sex, race, age, weight, height, and body mass index. Single-dose population PK was analyzed using first-order conditional estimation methods. A total of 151 participants were included in the analysis under fasted conditions, and 31 participants were included in the fed analysis. Under fasted conditions, a 10% change in body weight was accompanied by ~7.5% change in total body clearance (CL/F) and volume of distribution (V/F) of OC and APAP. Black participants had 17.3% lower CL/F and a 16.9% lower V/F of OC compared with white participants. Under fed conditions, the absorption rate constant of OC and APAP decreased significantly, although there was no effect on CL/F and V/F. Considering that the recommended dose for IR/ER OC/APAP 7.5/325 mg tablets is two tablets every 12 hours, adjustments of <50% are not clinically relevant. Dose adjustment may be necessary for large deviations from average body weight, but the small PK effects associated with race and consumption of a meal are not clinically relevant. PMID:26316698

  12. Pooled post hoc analysis of population pharmacokinetics of oxycodone and acetaminophen following a single oral dose of biphasic immediate-release/extended-release oxycodone/acetaminophen tablets.

    PubMed

    Franke, Ryan M; Morton, Terri; Devarakonda, Krishna

    2015-01-01

    This analysis evaluated the single-dose population pharmacokinetics (PK) of biphasic immediate-release (IR)/extended-release (ER) oxycodone (OC)/acetaminophen (APAP) 7.5/325 mg tablets administered under fasted conditions and the effects of a meal on their single-dose population PK. Data were pooled from four randomized, single-dose crossover trials enrolling healthy adult (18-55 years old) participants (three trials) and nondependent recreational users of prescription opioids (one trial) with a body weight of ≥59 kg. Participants received IR/ER OC/APAP 7.5/325 mg tablets in single doses of 7.5/325 mg (one tablet), 15/650 mg (two tablets), or 30/1,300 mg (four tablets) under fasted or fed conditions. Six variables were examined: sex, race, age, weight, height, and body mass index. Single-dose population PK was analyzed using first-order conditional estimation methods. A total of 151 participants were included in the analysis under fasted conditions, and 31 participants were included in the fed analysis. Under fasted conditions, a 10% change in body weight was accompanied by ~7.5% change in total body clearance (CL/F) and volume of distribution (V/F) of OC and APAP. Black participants had 17.3% lower CL/F and a 16.9% lower V/F of OC compared with white participants. Under fed conditions, the absorption rate constant of OC and APAP decreased significantly, although there was no effect on CL/F and V/F. Considering that the recommended dose for IR/ER OC/APAP 7.5/325 mg tablets is two tablets every 12 hours, adjustments of <50% are not clinically relevant. Dose adjustment may be necessary for large deviations from average body weight, but the small PK effects associated with race and consumption of a meal are not clinically relevant. PMID:26316698

  13. Post hoc Analysis for Detecting Individual Rare Variant Risk Associations Using Probit Regression Bayesian Variable Selection Methods in Case-Control Sequencing Studies.

    PubMed

    Larson, Nicholas B; McDonnell, Shannon; Albright, Lisa Cannon; Teerlink, Craig; Stanford, Janet; Ostrander, Elaine A; Isaacs, William B; Xu, Jianfeng; Cooney, Kathleen A; Lange, Ethan; Schleutker, Johanna; Carpten, John D; Powell, Isaac; Bailey-Wilson, Joan; Cussenot, Olivier; Cancel-Tassin, Geraldine; Giles, Graham; MacInnis, Robert; Maier, Christiane; Whittemore, Alice S; Hsieh, Chih-Lin; Wiklund, Fredrik; Catolona, William J; Foulkes, William; Mandal, Diptasri; Eeles, Rosalind; Kote-Jarai, Zsofia; Ackerman, Michael J; Olson, Timothy M; Klein, Christopher J; Thibodeau, Stephen N; Schaid, Daniel J

    2016-09-01

    Rare variants (RVs) have been shown to be significant contributors to complex disease risk. By definition, these variants have very low minor allele frequencies and traditional single-marker methods for statistical analysis are underpowered for typical sequencing study sample sizes. Multimarker burden-type approaches attempt to identify aggregation of RVs across case-control status by analyzing relatively small partitions of the genome, such as genes. However, it is generally the case that the aggregative measure would be a mixture of causal and neutral variants, and these omnibus tests do not directly provide any indication of which RVs may be driving a given association. Recently, Bayesian variable selection approaches have been proposed to identify RV associations from a large set of RVs under consideration. Although these approaches have been shown to be powerful at detecting associations at the RV level, there are often computational limitations on the total quantity of RVs under consideration and compromises are necessary for large-scale application. Here, we propose a computationally efficient alternative formulation of this method using a probit regression approach specifically capable of simultaneously analyzing hundreds to thousands of RVs. We evaluate our approach to detect causal variation on simulated data and examine sensitivity and specificity in instances of high RV dimensionality as well as apply it to pathway-level RV analysis results from a prostate cancer (PC) risk case-control sequencing study. Finally, we discuss potential extensions and future directions of this work. PMID:27312771

  14. Predictive factors of radiological progression after 2 years of remission-steered treatment in early arthritis patients: a post hoc analysis of the IMPROVED study

    PubMed Central

    Akdemir, Gülşah; Verheul, Marije K; Heimans, Lotte; Wevers-de Boer, Kirsten V C; Goekoop-Ruiterman, Yvonne P M; van Oosterhout, Maikel; Harbers, Joop B; Bijkerk, Casper; Steup-Beekman, Gerda M; Lard, Leroy R; Huizinga, Tom W J; Trouw, Leendert A; Allaart, Cornelia F

    2016-01-01

    Objectives To identify predictive factors of radiological progression in early arthritis patients treated by remission-steered treatment. Methods In the IMPROVED study, 610 patients with early rheumatoid arthritis (RA) or undifferentiated arthritis (UA) were treated with methotrexate (MTX) and a tapered high dose of prednisone. Patients in early remission (disease activity score (DAS) <1.6 after 4 months) tapered prednisone to zero. Patients not in early remission were randomised to arm 1: MTX plus hydroxychloroquine, sulfasalazine and prednisone, or to arm 2: MTX plus adalimumab. Predictors of radiological progression (≥0.5 Sharp/van der Heijde score; SHS) after 2 years were assessed using logistic regression analysis. Results Median (IQR) SHS progression in 488 patients was 0 (0–0) point, without differences between RA or UA patients or between treatment arms. In only 50/488 patients, the SHS progression was ≥0.5: 33 (66%) were in the early DAS remission group, 9 (18%) in arm 1, 5 (10%) in arm 2, 3 (6%) in the outside of protocol group. Age (OR (95% CI): 1.03 (1.00 to 1.06)) and the combined presence of anticarbamylated protein antibodies (anti-CarP) and anticitrullinated protein antibodies (ACPA) (2.54 (1.16 to 5.58)) were independent predictors for SHS progression. Symptom duration <12 weeks showed a trend. Conclusions After 2 years of remission steered treatment in early arthritis patients, there was limited SHS progression in only a small group of patients. Numerically, patients who had achieved early DAS remission had more SHS progression than other patients. Positivity for both anti-CarP and ACPA and age were independently associated with SHS progression. Trial registration numbers ISRCTN Register number 11916566 and EudraCT number 2006 06186-16. PMID:26925251

  15. Prevalence of acute and chronic viral seropositivity and characteristics of disease in patients with psoriatic arthritis treated with cyclosporine: a post hoc analysis from a sex point of view on the observational study of infectious events in psoriasis complicated by active psoriatic arthritis

    PubMed Central

    Colombo, Delia; Chimenti, Sergio; Grossi, Paolo Antonio; Marchesoni, Antonio; Bardazzi, Federico; Ayala, Fabio; Simoni, Lucia; Vassellatti, Donatella; Bellia, Gilberto

    2016-01-01

    Background Sex medicine studies have shown that there are sex differences with regard to disease characteristics in immune-mediated inflammatory diseases, including psoriasis, in immune response and susceptibility to viral infections. We performed a post hoc analysis of the Observational Study of infectious events in psoriasis complicated by active psoriatic arthritis (SYNERGY) study in patients with psoriatic arthritis (PsA) treated with immunosuppressive regimens including cyclosporine, in order to evaluate potential between-sex differences in severity of disease and prevalence of viral infections. Methods SYNERGY was an observational study conducted in 24 Italian dermatology clinics, which included 238 consecutively enrolled patients with PsA, under treatment with immunosuppressant regimens including cyclosporin A. In this post hoc analysis, patients’ demographical data and clinical characteristics of psoriasis, severity and activity of PsA, prevalence of seropositivity for at least one viral infection, and treatments administered for PsA and infections were compared between sexes. Results A total of 225 patients were evaluated in this post hoc analysis, and 121 (54%) were males. Demographic characteristics and concomitant diseases were comparable between sexes. Statistically significant sex differences were observed at baseline in Psoriasis Area and Severity Index score (higher in males), mean number of painful joints, Bath Ankylosing Spondylitis Disease Activity Index, and the global activity of disease assessed by patients (all higher in females). The percentage of patients with at least one seropositivity detected at baseline, indicative of concomitant or former viral infection, was significantly higher among women than among men. No between-sex differences were detected in other measures, at other time points, and in treatments. Patients developed no hepatitis B virus or hepatitis C virus reactivation during cyclosporine treatment. Conclusion Our post hoc

  16. Development of opioid-induced constipation: post hoc analysis of data from a 12-week prospective, open-label, blinded-endpoint streamlined study in low-back pain patients treated with prolonged-release WHO step III opioids

    PubMed Central

    Ueberall, Michael A; Mueller-Schwefe, Gerhard HH

    2015-01-01

    Background Opioid-induced constipation is the most prevalent patient complaint associated with longer-term opioid use and interferes with analgesic efficacy, functionality, quality of life, and patient compliance. Objectives We aimed to compare the effects of prolonged-release (PR) oxycodone plus PR naloxone (OXN) vs PR oxycodone (OXY) vs PR morphine (MOR) on bowel function under real-life conditions in chronic low-back pain patients refractory to World Health Organization (WHO) step I and/or II analgesics. Research design and methods This was a post hoc analysis of the complete data set from a prospective, randomized, open-label, blinded endpoint (PROBE) streamlined study (German pain study registry: 2012-0012-05; European Union Drug Regulating Authorities Clinical Trials [EudraCT]: 2012-001317-16), carried out in 88 centers in Germany, where a total of 901 patients requiring WHO step III opioids to treat low-back pain were enrolled and prospectively observed for 3 months. Opioid allocation was based on either optional randomization (n=453) or physician decision (n=448). In both groups, treatment doses could be adjusted as per the German prescribing information, and physicians were free to address all side effects and tolerability issues as usual. The primary endpoint was the proportion of patients maintaining normal bowel function throughout the complete treatment period, assessed with the Bowel Function Index (BFI). Secondary analyses addressed absolute and relative BFI changes, complete spontaneous bowel movements, use of laxatives, treatment emergent adverse events, analgesic effects, and differences between randomized vs nonrandomized patient groups. Results BFI changed significantly with all three WHO step III treatments, however significantly less with OXN vs OXY and MOR despite a significantly higher use of laxatives with the latter ones (P<0.001). The percentage of patients who maintained normal BFI scores despite opioid treatment was 54.5% (164/301) with

  17. Is herpes zoster an additional complication in old age alongside comorbidity and multiple medications? Results of the post hoc analysis of the 12-month longitudinal prospective observational ARIZONA cohort study

    PubMed Central

    Pickering, Gisèle; Gavazzi, Gaëtan; Gaillat, Jacques; Paccalin, Marc; Bloch, Karine; Bouhassira, Didier

    2016-01-01

    Objectives To examine the burden of comorbidity, polypharmacy and herpes zoster (HZ), an infectious disease, and its main complication post-herpetic neuralgia (PHN) in young (50–70 years of age: 70−) and old (≥70 years of age: 70+) patients. Design Post hoc analysis of the results of the 12-month longitudinal prospective multicentre observational ARIZONA cohort study. Settings and participants The study took place in primary care in France from 20 November 2006 to 12 September 2008. Overall, 644 general practitioners (GPs) collected data from 1358 patients aged 50 years or more with acute eruptive HZ. Outcome measures Presence of HZ-related pain or PHN (pain persisting >3 months) was documented at day 0 and at months 3, 6, and 12. To investigate HZ and PHN burden, pain, quality of life (QoL) and mood were self-assessed using validated questionnaires (Zoster Brief Pain Inventory, 12-item Short-Form health survey and Hospital Anxiety and Depression Scale, respectively). Results As compared with younger patients, older patients more frequently presented with comorbidities, more frequently took analgesics and had poorer response on all questionnaires, indicating greater burden, at inclusion. Analgesics were more frequently prescribed to relieve acute pain or PHN in 70+ than 70− patients. Despite higher levels of medication prescription, poorer pain relief and poorer response to all questionnaires were reported in 70+ than 70− patients. Conclusions Occurrence of HZ and progression to PHN adds extra burden on top of pharmacological treatment and impaired quality of life, especially in older patients who already have health problems to cope with in everyday life. PMID:26892790

  18. Anomaly Detection Techniques for Ad Hoc Networks

    ERIC Educational Resources Information Center

    Cai, Chaoli

    2009-01-01

    Anomaly detection is an important and indispensable aspect of any computer security mechanism. Ad hoc and mobile networks consist of a number of peer mobile nodes that are capable of communicating with each other absent a fixed infrastructure. Arbitrary node movements and lack of centralized control make them vulnerable to a wide variety of…

  19. 14 CFR 1203.903 - Ad hoc committees.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 5 2010-01-01 2010-01-01 false Ad hoc committees. 1203.903 Section 1203... NASA Information Security Program Committee § 1203.903 Ad hoc committees. The Chairperson is authorized to establish such ad hoc panels or subcommittees as may be necessary in the conduct of the...

  20. 14 CFR 1203.903 - Ad hoc committees.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 5 2011-01-01 2010-01-01 true Ad hoc committees. 1203.903 Section 1203.903... Information Security Program Committee § 1203.903 Ad hoc committees. The Chairperson is authorized to establish such ad hoc panels or subcommittees as may be necessary in the conduct of the Committee's work....

  1. 21 CFR 14.90 - Ad hoc advisory committee members.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Ad hoc advisory committee members. 14.90 Section... PUBLIC HEARING BEFORE A PUBLIC ADVISORY COMMITTEE Members of Advisory Committees § 14.90 Ad hoc advisory committee members. In selecting members of an ad hoc advisory committee, the Commissioner may use...

  2. 21 CFR 14.90 - Ad hoc advisory committee members.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Ad hoc advisory committee members. 14.90 Section... PUBLIC HEARING BEFORE A PUBLIC ADVISORY COMMITTEE Members of Advisory Committees § 14.90 Ad hoc advisory committee members. In selecting members of an ad hoc advisory committee, the Commissioner may use...

  3. 21 CFR 14.90 - Ad hoc advisory committee members.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Ad hoc advisory committee members. 14.90 Section... PUBLIC HEARING BEFORE A PUBLIC ADVISORY COMMITTEE Members of Advisory Committees § 14.90 Ad hoc advisory committee members. In selecting members of an ad hoc advisory committee, the Commissioner may use...

  4. 14 CFR § 1203.803 - Ad hoc committees.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 5 2014-01-01 2014-01-01 false Ad hoc committees. § 1203.803 Section Â... PROGRAM Delegation of Authority To Make Determinations in Original Classification Matters § 1203.803 Ad hoc committees. The Chairperson is authorized to establish such ad hoc panels or subcommittees as...

  5. 14 CFR 1203.903 - Ad hoc committees.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 5 2013-01-01 2013-01-01 false Ad hoc committees. 1203.903 Section 1203... NASA Information Security Program Committee § 1203.903 Ad hoc committees. The Chairperson is authorized to establish such ad hoc panels or subcommittees as may be necessary in the conduct of the...

  6. 21 CFR 14.90 - Ad hoc advisory committee members.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Ad hoc advisory committee members. 14.90 Section... PUBLIC HEARING BEFORE A PUBLIC ADVISORY COMMITTEE Members of Advisory Committees § 14.90 Ad hoc advisory committee members. In selecting members of an ad hoc advisory committee, the Commissioner may use...

  7. 14 CFR 1203.903 - Ad hoc committees.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 5 2012-01-01 2012-01-01 false Ad hoc committees. 1203.903 Section 1203... NASA Information Security Program Committee § 1203.903 Ad hoc committees. The Chairperson is authorized to establish such ad hoc panels or subcommittees as may be necessary in the conduct of the...

  8. 14 CFR § 1203.903 - Ad hoc committees.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 5 2014-01-01 2014-01-01 false Ad hoc committees. § 1203.903 Section Â... PROGRAM NASA Information Security Program Committee § 1203.903 Ad hoc committees. The Chairperson is authorized to establish such ad hoc panels or subcommittees as may be necessary in the conduct of...

  9. 21 CFR 14.90 - Ad hoc advisory committee members.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Ad hoc advisory committee members. 14.90 Section... PUBLIC HEARING BEFORE A PUBLIC ADVISORY COMMITTEE Members of Advisory Committees § 14.90 Ad hoc advisory committee members. In selecting members of an ad hoc advisory committee, the Commissioner may use...

  10. Supporting Dynamic Ad hoc Collaboration Capabilities

    SciTech Connect

    Agarwal, Deborah A.; Berket, Karlo

    2003-07-14

    Modern HENP experiments such as CMS and Atlas involve as many as 2000 collaborators around the world. Collaborations this large will be unable to meet often enough to support working closely together. Many of the tools currently available for collaboration focus on heavy-weight applications such as videoconferencing tools. While these are important, there is a more basic need for tools that support connecting physicists to work together on an ad hoc or continuous basis. Tools that support the day-to-day connectivity and underlying needs of a group of collaborators are important for providing light-weight, non-intrusive, and flexible ways to work collaboratively. Some example tools include messaging, file-sharing, and shared plot viewers. An important component of the environment is a scalable underlying communication framework. In this paper we will describe our current progress on building a dynamic and ad hoc collaboration environment and our vision for its evolution into a HENP collaboration environment.

  11. Routing Security in Ad Hoc Wireless Networks

    NASA Astrophysics Data System (ADS)

    Pervaiz, Mohammad O.; Cardei, Mihaela; Wu, Jie

    Wireless networks provide rapid, untethered access to information and computing, eliminating the barriers of distance, time, and location for many applications ranging from collaborative, distributed mobile computing to disaster recovery (such as fire, flood, earthquake), law enforcement (crowd control, search, and rescue), and military communications (command, control, surveillance, and reconnaissance). An ad hoc network is a collection of wireless mobile hosts forming a temporary network without the aid of any established infrastructure or centralized administration [11

  12. Effect of ferric carboxymaltose on serum phosphate and C-terminal FGF23 levels in non-dialysis chronic kidney disease patients: post-hoc analysis of a prospective study

    PubMed Central

    2013-01-01

    Background Some parenteral iron therapies have been found to be associated with hypophosphatemia. The mechanism of the decrease in serum phosphate is unknown. The aim of this study is to examine the effect of IV ferric carboxymaltose(FCM) on phosphate metabolism and FGF23 levels in patients with chronic kidney disease(CKD). Methods This is a post-hoc analysis of a prospective study carried out in 47 non-dialysis CKD patients with iron-deficiency anaemia who received a single 1000 mg injection of FCM. Markers of mineral metabolism (calcium, phosphate, 1,25-dihydroxyvitamin D, PTH and FGF23[c-terminal]) were measured prior to FCM administration and at week 3 and week 12 after FCM administration. Based on the measured levels of serum phosphate at week 3, patiens were classified as hypophosphatemic or non-hypophosphatemic. Results Serum phosphate levels decreased significantly three weeks after FCM administration and remained at lower levels at week 12 (4.24 ± 0.84 vs 3.69 ± 1.10 vs 3.83 ± 0.68 mg/dL, respectively, p < 0.0001. Serum calcium, PTH and 1,25-dihydroxyvitamin D did not change over the course of the study. Serum FGF23 decreased significantly from 442(44.9-4079.2) at baseline to 340(68.5-2603.3) at week 3 and 191.6(51.3-2465.9) RU/mL at week 12, p < 0.0001. Twelve patients were non-hypophosphatemic and 35 hypophosphatemic. FGF23 levels decreased in both groups, whereas no changes were documented in any of the other mineral parameters. Conclusions In non-dialysis CKD patients, FCM induces reduction in serum phosphate levels that persists for three months. FCM causes a significant decrease in FGF23 levels without changes to other bone metabolism parameters. PMID:23902731

  13. Energy Efficient Probabilistic Broadcasting for Mobile Ad-Hoc Network

    NASA Astrophysics Data System (ADS)

    Kumar, Sumit; Mehfuz, Shabana

    2016-08-01

    In mobile ad-hoc network (MANETs) flooding method is used for broadcasting route request (RREQ) packet from one node to another node for route discovery. This is the simplest method of broadcasting of RREQ packets but it often results in broadcast storm problem, originating collisions and congestion of packets in the network. A probabilistic broadcasting is one of the widely used broadcasting scheme for route discovery in MANETs and provides solution for broadcasting storm problem. But it does not consider limited energy of the battery of the nodes. In this paper, a new energy efficient probabilistic broadcasting (EEPB) is proposed in which probability of broadcasting RREQs is calculated with respect to remaining energy of nodes. The analysis of simulation results clearly indicate that an EEPB route discovery scheme in ad-hoc on demand distance vector (AODV) can increase the network lifetime with a decrease in the average power consumption and RREQ packet overhead. It also decreases the number of dropped packets in the network, in comparison to other EEPB schemes like energy constraint gossip (ECG), energy aware gossip (EAG), energy based gossip (EBG) and network lifetime through energy efficient broadcast gossip (NEBG).

  14. Worm epidemics in wireless ad hoc networks

    NASA Astrophysics Data System (ADS)

    Nekovee, Maziar

    2007-06-01

    A dramatic increase in the number of computing devices with wireless communication capability has resulted in the emergence of a new class of computer worms which specifically target such devices. The most striking feature of these worms is that they do not require Internet connectivity for their propagation but can spread directly from device to device using a short-range radio communication technology, such as WiFi or Bluetooth. In this paper, we develop a new model for epidemic spreading of these worms and investigate their spreading in wireless ad hoc networks via extensive Monte Carlo simulations. Our studies show that the threshold behaviour and dynamics of worm epidemics in these networks are greatly affected by a combination of spatial and temporal correlations which characterize these networks, and are significantly different from the previously studied epidemics in the Internet.

  15. Declarative ad-hoc sensor networking

    NASA Astrophysics Data System (ADS)

    Coffin, Daniel A.; Van Hook, Daniel J.; McGarry, Stephen M.; Kolek, Stephen R.

    2000-11-01

    Networking protocols for distributed collaborative ad-hoc wireless sensing are constrained by requirements such as energy efficiency, scalability, and support for greater variations in topology than traditional fully wired or last- hop wireless (remote to base station) networks. In such a highly constrained and dynamic environment, conventional networking approaches are generally not adequate. A declarative approach to network configuration and organization appears to offer significant benefits. Declarative networking exploits application-supplied data descriptions to control network routing and resource allocation in such a way as to enhance energy efficiency and scalability. An implementation of this approach, called the Declarative Routing Protocol (DRP) has been developed as part of DARPA's Sensor Information Technology program. This paper introduces the concept of declarative networking and what distinguishes it from more conventional networking approaches, describes the Declarative Routing Protocol, and presents performance results from initial experiments.

  16. Assured Information Sharing for Ad-Hoc Collaboration

    ERIC Educational Resources Information Center

    Jin, Jing

    2009-01-01

    Collaborative information sharing tends to be highly dynamic and often ad hoc among organizations. The dynamic natures and sharing patterns in ad-hoc collaboration impose a need for a comprehensive and flexible approach to reflecting and coping with the unique access control requirements associated with the environment. This dissertation…

  17. Receiver-Based Ad Hoc On Demand Multipath Routing Protocol for Mobile Ad Hoc Networks.

    PubMed

    Al-Nahari, Abdulaziz; Mohamad, Mohd Murtadha

    2016-01-01

    Decreasing the route rediscovery time process in reactive routing protocols is challenging in mobile ad hoc networks. Links between nodes are continuously established and broken because of the characteristics of the network. Finding multiple routes to increase the reliability is also important but requires a fast update, especially in high traffic load and high mobility where paths can be broken as well. The sender node keeps re-establishing path discovery to find new paths, which makes for long time delay. In this paper we propose an improved multipath routing protocol, called Receiver-based ad hoc on demand multipath routing protocol (RB-AOMDV), which takes advantage of the reliability of the state of the art ad hoc on demand multipath distance vector (AOMDV) protocol with less re-established discovery time. The receiver node assumes the role of discovering paths when finding data packets that have not been received after a period of time. Simulation results show the delay and delivery ratio performances are improved compared with AOMDV. PMID:27258013

  18. Receiver-Based Ad Hoc On Demand Multipath Routing Protocol for Mobile Ad Hoc Networks

    PubMed Central

    Al-Nahari, Abdulaziz; Mohamad, Mohd Murtadha

    2016-01-01

    Decreasing the route rediscovery time process in reactive routing protocols is challenging in mobile ad hoc networks. Links between nodes are continuously established and broken because of the characteristics of the network. Finding multiple routes to increase the reliability is also important but requires a fast update, especially in high traffic load and high mobility where paths can be broken as well. The sender node keeps re-establishing path discovery to find new paths, which makes for long time delay. In this paper we propose an improved multipath routing protocol, called Receiver-based ad hoc on demand multipath routing protocol (RB-AOMDV), which takes advantage of the reliability of the state of the art ad hoc on demand multipath distance vector (AOMDV) protocol with less re-established discovery time. The receiver node assumes the role of discovering paths when finding data packets that have not been received after a period of time. Simulation results show the delay and delivery ratio performances are improved compared with AOMDV. PMID:27258013

  19. Enhanced Weight based DSR for Mobile Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Verma, Samant; Jain, Sweta

    2011-12-01

    Routing in ad hoc network is a great problematic, since a good routing protocol must ensure fast and efficient packet forwarding, which isn't evident in ad hoc networks. In literature there exists lot of routing protocols however they don't include all the aspects of ad hoc networks as mobility, device and medium constraints which make these protocols not efficient for some configuration and categories of ad hoc networks. Thus in this paper we propose an improvement of Weight Based DSR in order to include some of the aspects of ad hoc networks as stability, remaining battery power, load and trust factor and proposing a new approach Enhanced Weight Based DSR.

  20. Possible association between phages, Hoc protein, and the immune system.

    PubMed

    Dabrowska, K; Switała-Jeleń, K; Opolski, A; Górski, A

    2006-02-01

    Mammals have become "an environment" for enterobacterial phage life cycles. Therefore it could be expected that bacteriophages adapt to them. This adaptation must comprise bacteriophage proteins. Gp Hoc seems to have significance neither for phage particle structure nor for phage antibacterial activity. It is evidently not necessary for the "typical" antibacterial actions of bacteriophages. But the rules of evolution make it improbable that gp Hoc really has no function, and non-essential genes of T4-type phages are probably important for phages' adaptation to their particular lifestyle. More interesting is the eukaryotic origin of gp Hoc: a resemblance to immunoglobulin-like proteins that reflects their evolutionary relation. Substantial differences in biological activity between T4 and a mutant that lacks gp Hoc were observed in a mammalian system. Hoc protein seems to be one of the molecules predicted to interact with mammalian organisms and/or modulate these interactions. PMID:16195787

  1. Spontaneous Ad Hoc Mobile Cloud Computing Network

    PubMed Central

    Lacuesta, Raquel; Sendra, Sandra; Peñalver, Lourdes

    2014-01-01

    Cloud computing helps users and companies to share computing resources instead of having local servers or personal devices to handle the applications. Smart devices are becoming one of the main information processing devices. Their computing features are reaching levels that let them create a mobile cloud computing network. But sometimes they are not able to create it and collaborate actively in the cloud because it is difficult for them to build easily a spontaneous network and configure its parameters. For this reason, in this paper, we are going to present the design and deployment of a spontaneous ad hoc mobile cloud computing network. In order to perform it, we have developed a trusted algorithm that is able to manage the activity of the nodes when they join and leave the network. The paper shows the network procedures and classes that have been designed. Our simulation results using Castalia show that our proposal presents a good efficiency and network performance even by using high number of nodes. PMID:25202715

  2. Malicious node detection in ad-hoc wireless networks

    NASA Astrophysics Data System (ADS)

    Griswold, Richard L.; Medidi, Sirisha R.

    2003-07-01

    Advances in wireless communications and the proliferation of mobile computing devices has led to the rise of a new type of computer network: the ad-hoc wireless network. Ad-hoc networks are characterized by a lack of fixed infrastructure, which give ad-hoc networks a great deal of flexibility, but also increases the risk of security problems. In wired networks, key pieces of network infrastructure are secured to prevent unauthorized physical access and tampering. Network administrators ensure that everything is properly configured and are on-hand to fix problems and deal with intrusions. In contrast, the nodes in an ad-hoc network are responsible for routing and forwarding data in the network, and there are no network administrators to handle potential problems. This makes an ad-hoc network more vulnerable to a misconfigured, faulty, or compromised node. We propose a means for a node in an ad-hoc network to detect and handle these malicious nodes by comparing data available to the routing protocol, such as cached routes in Dynamic Source Routing, ICMP messages, and transport layer information, such as TCP timeouts. This data can then be used along with network probes to isolate the malicious node.

  3. An Optimal CDS Construction Algorithm with Activity Scheduling in Ad Hoc Networks.

    PubMed

    Penumalli, Chakradhar; Palanichamy, Yogesh

    2015-01-01

    A new energy efficient optimal Connected Dominating Set (CDS) algorithm with activity scheduling for mobile ad hoc networks (MANETs) is proposed. This algorithm achieves energy efficiency by minimizing the Broadcast Storm Problem [BSP] and at the same time considering the node's remaining energy. The Connected Dominating Set is widely used as a virtual backbone or spine in mobile ad hoc networks [MANETs] or Wireless Sensor Networks [WSN]. The CDS of a graph representing a network has a significant impact on an efficient design of routing protocol in wireless networks. Here the CDS is a distributed algorithm with activity scheduling based on unit disk graph [UDG]. The node's mobility and residual energy (RE) are considered as parameters in the construction of stable optimal energy efficient CDS. The performance is evaluated at various node densities, various transmission ranges, and mobility rates. The theoretical analysis and simulation results of this algorithm are also presented which yield better results. PMID:26221627

  4. An Optimal CDS Construction Algorithm with Activity Scheduling in Ad Hoc Networks

    PubMed Central

    Penumalli, Chakradhar; Palanichamy, Yogesh

    2015-01-01

    A new energy efficient optimal Connected Dominating Set (CDS) algorithm with activity scheduling for mobile ad hoc networks (MANETs) is proposed. This algorithm achieves energy efficiency by minimizing the Broadcast Storm Problem [BSP] and at the same time considering the node's remaining energy. The Connected Dominating Set is widely used as a virtual backbone or spine in mobile ad hoc networks [MANETs] or Wireless Sensor Networks [WSN]. The CDS of a graph representing a network has a significant impact on an efficient design of routing protocol in wireless networks. Here the CDS is a distributed algorithm with activity scheduling based on unit disk graph [UDG]. The node's mobility and residual energy (RE) are considered as parameters in the construction of stable optimal energy efficient CDS. The performance is evaluated at various node densities, various transmission ranges, and mobility rates. The theoretical analysis and simulation results of this algorithm are also presented which yield better results. PMID:26221627

  5. Upper Bounding Service Capacity in Multihop Wireless SSMA-Based Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Du, Shirong; Daigle, John N.; Alidaee, Bahram

    Upper bounds on the service carrying capacity of a multihop, wireless, SSMA-based ad hoc network are considered herein. The network has a single radio band for transmission and reception. Each node can transmit to, or receive from, multiple nodes simultaneously. We formulate the scheduling of transmissions and control of transmit powers as a joint, mixed-integer, nonlinear optimization problem that yields maximum return at minimum power subject to SINR constraints. We present an efficient tabu search-based heuristic algorithm to solve the optimization problem and rigorously assess the quality of the results. Through analysis and simulation, we establish upper bounds on the VoIP call carrying capacity of the network as function of various parameters. We discuss the pros and cons of using SSMA as a spectrum sharing technique in wireless ad hoc networks

  6. Comparison of efficacy and safety of two starting insulin regimens in non-Asian, Asian Indian, and East Asian patients with type 2 diabetes: a post hoc analysis of the PARADIGM study

    PubMed Central

    Ji, Linong; Min, Kyung Wan; Oliveira, Juliana; Lew, Thomas; Duan, Ran

    2016-01-01

    Objective The objective of this study was to explore the efficacy and safety of insulin lispro mix 25 (25% insulin lispro and 75% insulin lispro protamine suspension [LM25]) or insulin glargine plus insulin lispro (G+L) in insulin-naïve patients with type 2 diabetes from different racial/ethnic groups. Methods Three subgroups from the PARADIGM study were analyzed post hoc: non-Asian (n=130), Asian Indian (n=106), and East Asian (n=89). Results All subgroups recorded glycated hemoglobin (HbA1c) reductions: non-Asian (LM25, −2.07%; G+L, −2.05%), Asian Indian (LM25, −1.75%; G+L, −1.60%), and East Asian (LM25, −2.03%; G+L, −1.76%); end point HbA1c values were higher in Asian Indians and East Asians than in non-Asians. Fewer Asian Indians (LM25, 43.2%; G+L, 29.2%) and East Asians (LM25, 37.5%; G+L, 36.1%) reached HbA1c <7% versus non-Asians (LM25, 51.7%; G+L, 48.1%); differences were not significant (P=0.12 and P=0.06, respectively). The mean total daily insulin dose (U/kg) for non-Asians was 0.67 (LM25) and 0.61 (G+L), for Asian Indians was 0.91 (LM25) and 0.90 (G+L), and for East Asians was 0.53 (LM25) and 0.59 (G+L). The ratio of mealtime to total insulin dose in the G+L arm for non-Asians was 0.19±0.23, for Asian Indians was 0.33±0.25, and for East Asians was 0.34±0.27. Overall incidence (%) of hypoglycemia in non-Asians was 94.1 (LM25) and 91.8 (G+L), in Asian Indians was 90.4 (LM25) and 88.5 (G+L), and in East Asians was 69.8 (LM25) and 77.3 (G+L). Conclusion Asian Indians showed least improvement in glycemic HbA1c reduction despite greater insulin use. East Asians and non-Asians achieved similar HbA1c reduction in the LM25 arm with a lower rate of hypoglycemia. Asians required more mealtime insulin coverage than non-Asians. This study added important insight into the effect of ethnicity on insulin treatment outcomes in patients with type 2 diabetes. PMID:27563254

  7. Energy-Saving Topology Control for Heterogeneous Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Zhang, Lei; Wang, Xuehui

    Topology control with per-node transmission power adjustment in wireless ad hoc networks has been shown to be effective with respect to prolonging network lifetime and increasing network capacity. In this paper, we propose a fully distributed, asynchronous and localized energy-saving topology control algorithm for heterogeneous ad hoc networks with non-uniform transmission ranges. We prove the topology derived from the algorithm preserves the network connectivity and bi-directionality. It need not the position system support and dramatically reduces the communication overhead compared to other topology control algorithms. Simulation results show the effectiveness of our proposed algorithm.

  8. Metadata-driven Ad Hoc Query of Clinical Studies Data

    PubMed Central

    Deshpande, Aniruddha M.; Nadkarni, Prakash M.

    2001-01-01

    The Entity-Attribute-Value (EAV) data representation is widely used in both clinical patient record systems (CPRSs) and clinical study data management systems (CSDMS). Both of these systems are heterogeneous in that many types of data are also represented conventionally, a situation that complicates data display, editing and ad hoc query. Seamless functioning of such systems mandates the presence of developer-defined metadata (data describing the rest of the database) that records, among other things, how individual parameters are represented within the system. We illustrate a web-based ad hoc query tool that relies on the metadata to generate syntactically and semantically correct SQL.

  9. Routing Protocol of Sparse Urban Vehicular Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Li, Huxiong

    Vehicular ad hoc network (VANET) is an application of mobile ad hoc technology in transportation systems, it has become an important part of ITS. Since multi-hop link is hard to set up in sparse VANET, a traffic-aware routing (TAR) protocol is proposed which estimates vehicle average neighbors (VAN) of roads by exchanging beacon messages between encounter vehicles. Road with high VAN is preferred to be selected as part of forwarding path at intersection. Packets are forwarded to the next intersection in road in a greedy manner. Simulations show that TAR outperforms the compared protocols in terms of both packet delivery ratio and average end-to-end delay.

  10. Multichannel MAC Layer In Mobile Ad—Hoc Network

    NASA Astrophysics Data System (ADS)

    Logesh, K.; Rao, Samba Siva

    2010-11-01

    This paper we presented the design objectives and technical challenges in Multichannel MAC protocols in Mobile Ad-hoc Network. In IEEE 802.11 a/b/g standards allow use of multiple channels, only a single channel is popularly used, due to the lack of efficient protocols that enable use of Multiple Channels. Even though complex environments in ad hoc networks require a combined control of physical (PHY) and medium access control (MAC) layers resources in order to optimize performance. And also we discuss the characteristics of cross-layer frame and give a multichannel MAC approach.

  11. 14 CFR § 1203.1002 - Ad hoc committees.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 5 2014-01-01 2014-01-01 false Ad hoc committees. § 1203.1002 Section § 1203.1002 Aeronautics and Space NATIONAL AERONAUTICS AND SPACE ADMINISTRATION INFORMATION SECURITY PROGRAM Special Access Programs (SAP) and Sensitive Compartmented Information (SCI) Programs...

  12. Report of the Ad Hoc Committee on Scope and Sequence.

    ERIC Educational Resources Information Center

    Hergesheimer, John; And Others

    1989-01-01

    Describes the establishment of the Ad Hoc Committee on Scope and Sequence by the National Council for the Social Studies (NCSS). Outlines the responsibilities of the Committee, the process used to formulate curriculum criteria and the resultant criteria for social studies education curriculum design. (SLM)

  13. Providing Location Security in Vehicular Ad Hoc Networks

    ERIC Educational Resources Information Center

    Yan, Gongjun

    2010-01-01

    Location is fundamental information in Vehicular Ad-hoc Networks (VANETs). Almost all VANET applications rely on location information. Therefore it is of importance to ensure location information integrity, meaning that location information is original (from the generator), correct (not bogus or fabricated) and unmodified (value not changed). We…

  14. Routing in Ad Hoc Network Using Ant Colony Optimization

    NASA Astrophysics Data System (ADS)

    Khanpara, Pimal; Valiveti, Sharada; Kotecha, K.

    The ad hoc networks have dynamic topology and are infrastructure less. So it is required to implement a new network protocol for providing efficient end to end communication based on TCP/IP structure. There is a need to re-define or modify the functions of each layer of TCP/IP model to provide end to end communication between nodes. The mobility of the nodes and the limited resources are the main reason for this change. The main challenge in ad hoc networks is routing. Due to the mobility of the nodes in the ad hoc networks, routing becomes very difficult. Ant based algorithms are suitable for routing in ad hoc networks due to its dynamic nature and adaptive behavior. There are number of routing algorithms based on the concept of ant colony optimizations. It is quite difficult to determine the best ant based algorithm for routing as these algorithms perform differently under various circumstances such as the traffic distribution and network topology. In this paper, the overview of such routing algorithms is given.

  15. Ad hoc CubeSat constellations: Secondary launch coverage and distribution

    NASA Astrophysics Data System (ADS)

    Marinan, A.; Nicholas, A.; Cahoy, K.

    The primary purpose of a constellation is to obtain global measurements with improved spatial and temporal resolution. The small size, low cost, standardized form factor, and increasing availability of commercial parts for CubeSats make them ideal for use in constellations. However, without taking advantage of secondary payload opportunities, it would be costly to launch and distribute a CubeSat constellation into a specific configuration. A cost-effective way to launch a constellation of CubeSats is via consecutive secondary payload launch opportunities, but the resulting constellation would be an ad hoc mix of orbit parameters. We focus on the feasibility of cobbling together constellation-like functionality from multiple secondary payload opportunities. Each participating CubeSat (or set of CubeSats) per launch could have completely different orbital parameters, even without propulsion onboard the CubeSats or intermediate transfer carriers. We look at the ground coverages that could be obtained for a constellation of five to six orbital planes with one to six satellites in each plane. We analyze past and announced future launch opportunities for CubeSats, including launch platforms supported by the NASA Educational Launch of Nanosatellites (ELaNa). We consider combinations of possible launch locations and temporal spacings over the course of one year and simulate the resulting ground coverage patterns and revisit times for an ad hoc constellation using these launch opportunities. We perform this analysis for two separate case studies - one with only US launches and one with both US and non-US opportunities - and vary the number of satellites per orbital plane. Typical CubeSat mission lifetimes and deorbit times for low-altitude orbits are included in these analyses. The ad hoc constellation results are compared to coverage from uniformly-placed LEO constellations and are quantified in terms of revisit time, time to 100% global coverage, and response time. For mu

  16. Effusion of hydrophobic organic compounds (HOCs) from fog droplets

    SciTech Connect

    Lee, W.M.; Tsay, C.

    1998-12-31

    In this study, the effects of surface-active substances, pH and salt on the effusion of HOCs from droplets were investigated. An HOCs-effusion reactor was established for experiments. N-octane was used for the HOCs and Sodium Dodecyl Sulfate (SDS) was selected as the surface-active substance. A correction factor to mass exchange constant, defined as the deviation of exchange constant of n-octane in fog phase from that in planar aqueous phase was used to quantify the effects of surface-active substance, pH, and salt concentration on the effusion rate of HOCs from fog droplets by a modified double-layer diffusion model. The results showed that surface-active substances, SDS cab decrease the effusion rate of n-octane from fog droplets by about 40%--62% and the values of were in the range of 0.382 to 0.609. The salt, sodium chloride, at the concentration of 1.00 {times} 10{sup {minus}3} [M] can further decrease the mass transfer rate of n-octane from fog droplets because the values changed from 0.590 to 0.368, so that the effusion rate was further decrease by salt. When pH values were between 5.60 and 2.00, values varied from 0.609 to 0.367 at SDS concentration of 1.00 x 10{sup 3}[M]. This indicated that the effusion rate of HOCs from fog droplets decreased with decreasing pH value.

  17. Determination of endogenous concentration of γ-hydroxybutyric acid (GHB) in hair through an ad hoc GC-MS analysis: A study on a wide population and influence of gender and age.

    PubMed

    Vaiano, Fabio; Serpelloni, Giovanni; Furlanetto, Sandra; Palumbo, Diego; Mari, Francesco; Fioravanti, Alessia; Bertol, Elisabetta

    2016-01-25

    γ-Hydroxybutyric acid (GHB) spread for recreational purposes or as "rape drug" represents a hard issue for forensic toxicologists due to its endogenous nature. It is clear that an actual and reliable discrimination between basal and exogenous levels is mandatory to achieve a correct evaluation of conscious/unconscious administration. This research aimed to study the GHB baseline in hair samples, collected from 150 volunteers, non-consumers of any drugs of abuse, in order to evaluate if a generic cut-off value could be accepted, also focusing on potential influences of gender and age. The analysis consisted of an overnight incubation with NaOH at 56 °C, liquid-liquid extraction with ethylacetate and trimethylsylil derivatization. Detection was carried out through gas chromatography-mass spectrometry in single ion monitoring (m/z 233, 234, 147 for GHB; m/z 239, 240 and 147 for GHB-d6). The endogenous amount in "blank" hair was estimated by the standard addition method. Concentration range was 0.279-2.839 ng/mg. In males, the average GHB levels were higher than in females (0.829 vs 0.596 ng/mg, respectively), especially in the first age category (<30 years, 1.008 vs 0.606 ng/mg, respectively). Age influences on GHB levels seemed to be different among the two sexes: in male population concentrations were higher <30 (1.008 ng/mg) and similar in the other age ranges (0.762 ng/mg, 30-50; 0.763 ng/mg, >50); in female, quite similar levels were registered throughout all the age categories (0.606 ng/mg, <30; 0.536 ng/mg, 30-50; 0.691 ng/mg, >50). Further study should be performed on GHB physiology in order to better understand these differences among ages and genders. Moreover, we demonstrated that for hair analysis a cut-off reference value is not strictly mandatory, underlining the great interpretative valence of segmental analysis. PMID:26551534

  18. 29 CFR 1912.11 - Terms of ad hoc committee members.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 29 Labor 7 2010-07-01 2010-07-01 false Terms of ad hoc committee members. 1912.11 Section 1912.11..., DEPARTMENT OF LABOR (CONTINUED) ADVISORY COMMITTEES ON STANDARDS Organizational Matters § 1912.11 Terms of ad hoc committee members. Each member of an ad hoc advisory committee shall serve for such period as...

  19. 29 CFR 1912.11 - Terms of ad hoc committee members.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 29 Labor 7 2013-07-01 2013-07-01 false Terms of ad hoc committee members. 1912.11 Section 1912.11..., DEPARTMENT OF LABOR (CONTINUED) ADVISORY COMMITTEES ON STANDARDS Organizational Matters § 1912.11 Terms of ad hoc committee members. Each member of an ad hoc advisory committee shall serve for such period as...

  20. 29 CFR 1912.11 - Terms of ad hoc committee members.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 29 Labor 7 2012-07-01 2012-07-01 false Terms of ad hoc committee members. 1912.11 Section 1912.11..., DEPARTMENT OF LABOR (CONTINUED) ADVISORY COMMITTEES ON STANDARDS Organizational Matters § 1912.11 Terms of ad hoc committee members. Each member of an ad hoc advisory committee shall serve for such period as...

  1. 29 CFR 1912.11 - Terms of ad hoc committee members.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 29 Labor 7 2014-07-01 2014-07-01 false Terms of ad hoc committee members. 1912.11 Section 1912.11..., DEPARTMENT OF LABOR (CONTINUED) ADVISORY COMMITTEES ON STANDARDS Organizational Matters § 1912.11 Terms of ad hoc committee members. Each member of an ad hoc advisory committee shall serve for such period as...

  2. 29 CFR 1912.11 - Terms of ad hoc committee members.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 29 Labor 7 2011-07-01 2011-07-01 false Terms of ad hoc committee members. 1912.11 Section 1912.11..., DEPARTMENT OF LABOR (CONTINUED) ADVISORY COMMITTEES ON STANDARDS Organizational Matters § 1912.11 Terms of ad hoc committee members. Each member of an ad hoc advisory committee shall serve for such period as...

  3. Efficacy and safety of liraglutide, a once-daily human glucagon-like peptide-1 analogue, in Latino/Hispanic patients with type 2 diabetes: post hoc analysis of data from four phase III trials.

    PubMed

    Davidson, J A; Ørsted, D D; Campos, C

    2016-07-01

    The aim of the present analysis was to evaluate the efficacy of the glucagon-like peptide-1 receptor agonist liraglutide in Latino/Hispanic individuals with type 2 diabetes, in addition to comparing its treatment effects with those observed in non-Latino/Hispanic individuals. Analyses were performed on patient-level data from a subset of individuals self-defined as Latino/Hispanic from four phase III studies, the LEAD-3, LEAD-4, LEAD-6 and 1860-LIRA-DPP-4 trials. Endpoints included change in glycated haemoglobin (HbA1c) and body weight from baseline. In Latino/Hispanic patients (n = 505; 323 treated with liraglutide) after 26 weeks, mean HbA1c reductions were significantly greater with both liraglutide 1.2 and 1.8 mg versus comparator or placebo in the LEAD-3 and LEAD-4 studies, and with 1.8 mg liraglutide in the 1860-LIRA-DPP-4 trial. In LEAD-3 both doses led to significant differences in body weight change among Latino/Hispanic patients versus the comparator. With 1.8 mg liraglutide, difference in weight change was significant only in the 1860-LIRA-DPP-4 trial versus sitagliptin. For both endpoints Latino/Hispanic and non-Latino/Hispanic patients responded to liraglutide similarly. In summary, liraglutide is efficacious for treatment of type 2 diabetes in Latino/Hispanic patients, with a similar efficacy to that seen in non-Latino/Hispanic patients. PMID:26936426

  4. Can the spinal instability neoplastic score prior to spinal radiosurgery predict compression fractures following stereotactic spinal radiosurgery for metastatic spinal tumor?: a post hoc analysis of prospective phase II single-institution trials.

    PubMed

    Lee, Sun-Ho; Tatsui, Claudio E; Ghia, Amol J; Amini, Behrang; Li, Jing; Zavarella, Salvatore M; Tannir, Nizar M; Brown, Paul D; Rhines, Laurence D

    2016-02-01

    The aim of this study was to determine the predictability of vertebral compression fracture (VCF) development applying the spinal instability neoplastic score (SINS) prior to delivery of stereotactic spinal radiosurgery (SSRS) for spinal metastases. From two prospective cohorts of SSRS for spinal metastases, we selected patients with a low degree of cord compression or cauda equine from C3 to S1 and analyzed 79 patients enrolled according to binary SINS criteria. The primary endpoint was the development of a de novo VCF or progression of an existing fracture after SSRS. We identified 32 fractures (40.5 %): 19 de novo and 13 progressive. The mean time to fracture after SSRT was 3.3 months (range, 0.4-34.1 months). In 41 patients with low SINS (0-6), 7 patients (17.1 %) developed a fracture after SSRS. In 38 patients with high SINS (7-12), 25 (65.8 %) developed a fracture. Among the 32 fractures, 15 were symptomatic. Patients with high SINS were more likely to experience symptomatic fractures (31.6 %) than were patients with lower SINS (7.4 %). On univariate and multivariate analysis, 24-month fracture-free rates were 78.7 and 33.7 % in low and high SINS group, respectively and high SINS was found to be a significant risk factor for VCFs and symptomatic fractures (respectively, HR 5.6, p = 0.04; HR 5.3, p = 0.01). SINS is a useful tool for predicting the development of VCF after SSRS for spinal metastases. Prophylactic cement augmentation should not be considered for patients with lower SINS, since the risk of fracture is low. PMID:26643804

  5. Randomised comparison of zofenopril and ramipril plus acetylsalicylic acid in postmyocardial infarction patients with left ventricular systolic dysfunction: a post hoc analysis of the SMILE-4 Study in patients according to levels of left ventricular ejection fraction at entry

    PubMed Central

    Borghi, Claudio; Omboni, Stefano; Cicero, Arrigo FG; Bacchelli, Stefano; Degli Esposti, Daniela; Novo, Salvatore; Vinereanu, Dragos; Ambrosio, Giuseppe; Ambrosioni, Ettore

    2015-01-01

    Objective Conflicting evidence exists on the benefits of treating patients with coronary artery disease and preserved left ventricular ejection fraction (LVEF) with an ACE inhibitor. This retrospective analysis of the SMILE-4 Study sought to compare the efficacy of zofenopril 60 mg plus acetylsalicylic acid (ASA) versus ramipril 10 mg plus ASA 100 mg in patients with acute myocardial infarction (AMI) and heart failure, according to an impaired or preserved LVEF. Methods The primary study end point was 1-year combined occurrence of death or hospitalisation for cardiovascular causes. A preserved LVEF was defined by a baseline LVEF >40% and an impaired one by an LVEF ≤40%. Results 448 patients (63%) had preserved and 262 (37%) had impaired LVEF. The primary end point occurred in 125 patients with preserved (28%) and 106 patients with impaired LVEF (41%, p=0.001). In the first group, the rate of major cardiovascular events was significantly lower under zofenopril than under ramipril (23% vs 33%; OR and 95% CI 0.60, 0.39 to 0.91; p=0.016). This was also the case for patients with impaired LVEF, though between-group difference was not statistically significant (38% zofenopril vs 44% ramipril; OR 0.77, 0.47 to 1.26; p=0.297). LVEF values significantly (p<0.0001) increased during the follow-up in both subsets with no between-treatment differences. However, improvement rates in LVEF (increase ≥5%) were higher in patients with impaired LVEF (72% vs 61%, p=0.006). Conclusions In the SMILE-4 Study, the cardiovascular outcome of patients with post-AMI with preserved LVEF was more favourable in the zofenopril than in the ramipril treatment group. Trial registration number EudraCT Number: 2004-001150-88 (http://www.clinicaltrialsregister.eu); Italian Ministry of Health Code: GUIDOTT_III_2004_001 (https://oss-sper-clin.agenziafarmaco.it). PMID:26288740

  6. MWAHCA: A Multimedia Wireless Ad Hoc Cluster Architecture

    PubMed Central

    Diaz, Juan R.; Jimenez, Jose M.; Sendra, Sandra

    2014-01-01

    Wireless Ad hoc networks provide a flexible and adaptable infrastructure to transport data over a great variety of environments. Recently, real-time audio and video data transmission has been increased due to the appearance of many multimedia applications. One of the major challenges is to ensure the quality of multimedia streams when they have passed through a wireless ad hoc network. It requires adapting the network architecture to the multimedia QoS requirements. In this paper we propose a new architecture to organize and manage cluster-based ad hoc networks in order to provide multimedia streams. Proposed architecture adapts the network wireless topology in order to improve the quality of audio and video transmissions. In order to achieve this goal, the architecture uses some information such as each node's capacity and the QoS parameters (bandwidth, delay, jitter, and packet loss). The architecture splits the network into clusters which are specialized in specific multimedia traffic. The real system performance study provided at the end of the paper will demonstrate the feasibility of the proposal. PMID:24737996

  7. Auto-Configuration Protocols in Mobile Ad Hoc Networks

    PubMed Central

    Villalba, Luis Javier García; Matesanz, Julián García; Orozco, Ana Lucila Sandoval; Díaz, José Duván Márquez

    2011-01-01

    The TCP/IP protocol allows the different nodes in a network to communicate by associating a different IP address to each node. In wired or wireless networks with infrastructure, we have a server or node acting as such which correctly assigns IP addresses, but in mobile ad hoc networks there is no such centralized entity capable of carrying out this function. Therefore, a protocol is needed to perform the network configuration automatically and in a dynamic way, which will use all nodes in the network (or part thereof) as if they were servers that manage IP addresses. This article reviews the major proposed auto-configuration protocols for mobile ad hoc networks, with particular emphasis on one of the most recent: D2HCP. This work also includes a comparison of auto-configuration protocols for mobile ad hoc networks by specifying the most relevant metrics, such as a guarantee of uniqueness, overhead, latency, dependency on the routing protocol and uniformity. PMID:22163814

  8. Auto-configuration protocols in mobile ad hoc networks.

    PubMed

    Villalba, Luis Javier García; Matesanz, Julián García; Orozco, Ana Lucila Sandoval; Díaz, José Duván Márquez

    2011-01-01

    The TCP/IP protocol allows the different nodes in a network to communicate by associating a different IP address to each node. In wired or wireless networks with infrastructure, we have a server or node acting as such which correctly assigns IP addresses, but in mobile ad hoc networks there is no such centralized entity capable of carrying out this function. Therefore, a protocol is needed to perform the network configuration automatically and in a dynamic way, which will use all nodes in the network (or part thereof) as if they were servers that manage IP addresses. This article reviews the major proposed auto-configuration protocols for mobile ad hoc networks, with particular emphasis on one of the most recent: D2HCP. This work also includes a comparison of auto-configuration protocols for mobile ad hoc networks by specifying the most relevant metrics, such as a guarantee of uniqueness, overhead, latency, dependency on the routing protocol and uniformity. PMID:22163814

  9. MAC Protocol for Ad Hoc Networks Using a Genetic Algorithm

    PubMed Central

    Elizarraras, Omar; Panduro, Marco; Méndez, Aldo L.

    2014-01-01

    The problem of obtaining the transmission rate in an ad hoc network consists in adjusting the power of each node to ensure the signal to interference ratio (SIR) and the energy required to transmit from one node to another is obtained at the same time. Therefore, an optimal transmission rate for each node in a medium access control (MAC) protocol based on CSMA-CDMA (carrier sense multiple access-code division multiple access) for ad hoc networks can be obtained using evolutionary optimization. This work proposes a genetic algorithm for the transmission rate election considering a perfect power control, and our proposition achieves improvement of 10% compared with the scheme that handles the handshaking phase to adjust the transmission rate. Furthermore, this paper proposes a genetic algorithm that solves the problem of power combining, interference, data rate, and energy ensuring the signal to interference ratio in an ad hoc network. The result of the proposed genetic algorithm has a better performance (15%) compared to the CSMA-CDMA protocol without optimizing. Therefore, we show by simulation the effectiveness of the proposed protocol in terms of the throughput. PMID:25140339

  10. MAC protocol for ad hoc networks using a genetic algorithm.

    PubMed

    Elizarraras, Omar; Panduro, Marco; Méndez, Aldo L; Reyna, Alberto

    2014-01-01

    The problem of obtaining the transmission rate in an ad hoc network consists in adjusting the power of each node to ensure the signal to interference ratio (SIR) and the energy required to transmit from one node to another is obtained at the same time. Therefore, an optimal transmission rate for each node in a medium access control (MAC) protocol based on CSMA-CDMA (carrier sense multiple access-code division multiple access) for ad hoc networks can be obtained using evolutionary optimization. This work proposes a genetic algorithm for the transmission rate election considering a perfect power control, and our proposition achieves improvement of 10% compared with the scheme that handles the handshaking phase to adjust the transmission rate. Furthermore, this paper proposes a genetic algorithm that solves the problem of power combining, interference, data rate, and energy ensuring the signal to interference ratio in an ad hoc network. The result of the proposed genetic algorithm has a better performance (15%) compared to the CSMA-CDMA protocol without optimizing. Therefore, we show by simulation the effectiveness of the proposed protocol in terms of the throughput. PMID:25140339

  11. T2AR: trust-aware ad-hoc routing protocol for MANET.

    PubMed

    Dhananjayan, Gayathri; Subbiah, Janakiraman

    2016-01-01

    Secure data transfer against the malicious attacks is an important issue in an infrastructure-less independent network called mobile ad-hoc network (MANET). Trust assurance between MANET nodes is the key parameter in the high-security provision under dynamic topology variations and open wireless constraints. But, the malicious behavior of nodes reduces the trust level of the nodes that leads to an insecure data delivery. The increase in malicious attacks causes the excessive energy consumption that leads to a reduction of network lifetime. The lack of positional information update of the nodes in ad-hoc on-demand vector (AODV) protocol during the connection establishment offers less trust level between the nodes. Hence, the trust rate computation using energy and mobility models and its update are the essential tasks for secure data delivery. This paper proposes a trust-aware ad-hoc routing (T2AR) protocol to improve the trust level between the nodes in MANET. The proposed method modifies the traditional AODV routing protocol with the constraints of trust rate, energy, mobility based malicious behavior prediction. The packet sequence ID matching from the log reports of neighbor nodes determine the trust rate that avoids the malicious report generation. Besides, the direct and indirect trust observation schemes utilization increases the trust level. Besides, the received signal strength indicator utilization determines the trusted node is within the communication range or not. The comparative analysis between the proposed T2AR with the existing methods such as TRUNCMAN, RBT, GR, FBR and DICOTIDS regarding the average end-to-end delay, throughput, false positives, packet delivery ratio shows the effectiveness of T2AR in the secure MANET environment design. PMID:27441127

  12. The choice of product indicators in latent variable interaction models: post hoc analyses.

    PubMed

    Foldnes, Njål; Hagtvet, Knut Arne

    2014-09-01

    The unconstrained product indicator (PI) approach is a simple and popular approach for modeling nonlinear effects among latent variables. This approach leaves the practitioner to choose the PIs to be included in the model, introducing arbitrariness into the modeling. In contrast to previous Monte Carlo studies, we evaluated the PI approach by 3 post hoc analyses applied to a real-world case adopted from a research effort in social psychology. The measurement design applied 3 and 4 indicators for the 2 latent 1st-order variables, leaving the researcher with a choice among more than 4,000 possible PI configurations. Sixty so-called matched-pair configurations that have been recommended in previous literature are of special interest. In the 1st post hoc analysis we estimated the interaction effect for all PI configurations, keeping the real-world sample fixed. The estimated interaction effect was substantially affected by the choice of PIs, also across matched-pair configurations. Subsequently, a post hoc Monte Carlo study was conducted, with varying sample sizes and data distributions. Convergence, bias, Type I error and power of the interaction test were investigated for each matched-pair configuration and the all-pairs configuration. Variation in estimates across matched-pair configurations for a typical sample was substantial. The choice of specific configuration significantly affected convergence and the interaction test's outcome. The all-pairs configuration performed overall better than the matched-pair configurations. A further advantage of the all-pairs over the matched-pairs approach is its unambiguity. The final study evaluates the all-pairs configuration for small sample sizes and compares it to the non-PI approach of latent moderated structural equations. PMID:24773360

  13. Dynamic fair node spectrum allocation for ad hoc networks using random matrices

    NASA Astrophysics Data System (ADS)

    Rahmes, Mark; Lemieux, George; Chester, Dave; Sonnenberg, Jerry

    2015-05-01

    Dynamic Spectrum Access (DSA) is widely seen as a solution to the problem of limited spectrum, because of its ability to adapt the operating frequency of a radio. Mobile Ad Hoc Networks (MANETs) can extend high-capacity mobile communications over large areas where fixed and tethered-mobile systems are not available. In one use case with high potential impact, cognitive radio employs spectrum sensing to facilitate the identification of allocated frequencies not currently accessed by their primary users. Primary users own the rights to radiate at a specific frequency and geographic location, while secondary users opportunistically attempt to radiate at a specific frequency when the primary user is not using it. We populate a spatial radio environment map (REM) database with known information that can be leveraged in an ad hoc network to facilitate fair path use of the DSA-discovered links. Utilization of high-resolution geospatial data layers in RF propagation analysis is directly applicable. Random matrix theory (RMT) is useful in simulating network layer usage in nodes by a Wishart adjacency matrix. We use the Dijkstra algorithm for discovering ad hoc network node connection patterns. We present a method for analysts to dynamically allocate node-node path and link resources using fair division. User allocation of limited resources as a function of time must be dynamic and based on system fairness policies. The context of fair means that first available request for an asset is not envied as long as it is not yet allocated or tasked in order to prevent cycling of the system. This solution may also save money by offering a Pareto efficient repeatable process. We use a water fill queue algorithm to include Shapley value marginal contributions for allocation.

  14. A multihop key agreement scheme for wireless ad hoc networks based on channel characteristics.

    PubMed

    Hao, Zhuo; Zhong, Sheng; Yu, Nenghai

    2013-01-01

    A number of key agreement schemes based on wireless channel characteristics have been proposed recently. However, previous key agreement schemes require that two nodes which need to agree on a key are within the communication range of each other. Hence, they are not suitable for multihop wireless networks, in which nodes do not always have direct connections with each other. In this paper, we first propose a basic multihop key agreement scheme for wireless ad hoc networks. The proposed basic scheme is resistant to external eavesdroppers. Nevertheless, this basic scheme is not secure when there exist internal eavesdroppers or Man-in-the-Middle (MITM) adversaries. In order to cope with these adversaries, we propose an improved multihop key agreement scheme. We show that the improved scheme is secure against internal eavesdroppers and MITM adversaries in a single path. Both performance analysis and simulation results demonstrate that the improved scheme is efficient. Consequently, the improved key agreement scheme is suitable for multihop wireless ad hoc networks. PMID:23766725

  15. A Multihop Key Agreement Scheme for Wireless Ad Hoc Networks Based on Channel Characteristics

    PubMed Central

    Yu, Nenghai

    2013-01-01

    A number of key agreement schemes based on wireless channel characteristics have been proposed recently. However, previous key agreement schemes require that two nodes which need to agree on a key are within the communication range of each other. Hence, they are not suitable for multihop wireless networks, in which nodes do not always have direct connections with each other. In this paper, we first propose a basic multihop key agreement scheme for wireless ad hoc networks. The proposed basic scheme is resistant to external eavesdroppers. Nevertheless, this basic scheme is not secure when there exist internal eavesdroppers or Man-in-the-Middle (MITM) adversaries. In order to cope with these adversaries, we propose an improved multihop key agreement scheme. We show that the improved scheme is secure against internal eavesdroppers and MITM adversaries in a single path. Both performance analysis and simulation results demonstrate that the improved scheme is efficient. Consequently, the improved key agreement scheme is suitable for multihop wireless ad hoc networks. PMID:23766725

  16. Power-Aware Intrusion Detection in Mobile Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Şen, Sevil; Clark, John A.; Tapiador, Juan E.

    Mobile ad hoc networks (MANETs) are a highly promising new form of networking. However they are more vulnerable to attacks than wired networks. In addition, conventional intrusion detection systems (IDS) are ineffective and inefficient for highly dynamic and resource-constrained environments. Achieving an effective operational MANET requires tradeoffs to be made between functional and non-functional criteria. In this paper we show how Genetic Programming (GP) together with a Multi-Objective Evolutionary Algorithm (MOEA) can be used to synthesise intrusion detection programs that make optimal tradeoffs between security criteria and the power they consume.

  17. Ad Hoc Selection of Voice over Internet Streams

    NASA Technical Reports Server (NTRS)

    Macha, Mitchell G. (Inventor); Bullock, John T. (Inventor)

    2008-01-01

    A method and apparatus for a communication system technique involving ad hoc selection of at least two audio streams is provided. Each of the at least two audio streams is a packetized version of an audio source. A data connection exists between a server and a client where a transport protocol actively propagates the at least two audio streams from the server to the client. Furthermore, software instructions executable on the client indicate a presence of the at least two audio streams, allow selection of at least one of the at least two audio streams, and direct the selected at least one of the at least two audio streams for audio playback.

  18. Ad Hoc Selection of Voice over Internet Streams

    NASA Technical Reports Server (NTRS)

    Macha, Mitchell G. (Inventor); Bullock, John T. (Inventor)

    2014-01-01

    A method and apparatus for a communication system technique involving ad hoc selection of at least two audio streams is provided. Each of the at least two audio streams is a packetized version of an audio source. A data connection exists between a server and a client where a transport protocol actively propagates the at least two audio streams from the server to the client. Furthermore, software instructions executable on the client indicate a presence of the at least two audio streams, allow selection of at least one of the at least two audio streams, and direct the selected at least one of the at least two audio streams for audio playback.

  19. Scalable Architecture for Multihop Wireless ad Hoc Networks

    NASA Technical Reports Server (NTRS)

    Arabshahi, Payman; Gray, Andrew; Okino, Clayton; Yan, Tsun-Yee

    2004-01-01

    A scalable architecture for wireless digital data and voice communications via ad hoc networks has been proposed. Although the details of the architecture and of its implementation in hardware and software have yet to be developed, the broad outlines of the architecture are fairly clear: This architecture departs from current commercial wireless communication architectures, which are characterized by low effective bandwidth per user and are not well suited to low-cost, rapid scaling in large metropolitan areas. This architecture is inspired by a vision more akin to that of more than two dozen noncommercial community wireless networking organizations established by volunteers in North America and several European countries.

  20. A User Authentication Scheme Based on Elliptic Curves Cryptography for Wireless Ad Hoc Networks.

    PubMed

    Chen, Huifang; Ge, Linlin; Xie, Lei

    2015-01-01

    The feature of non-infrastructure support in a wireless ad hoc network (WANET) makes it suffer from various attacks. Moreover, user authentication is the first safety barrier in a network. A mutual trust is achieved by a protocol which enables communicating parties to authenticate each other at the same time and to exchange session keys. For the resource-constrained WANET, an efficient and lightweight user authentication scheme is necessary. In this paper, we propose a user authentication scheme based on the self-certified public key system and elliptic curves cryptography for a WANET. Using the proposed scheme, an efficient two-way user authentication and secure session key agreement can be achieved. Security analysis shows that our proposed scheme is resilient to common known attacks. In addition, the performance analysis shows that our proposed scheme performs similar or better compared with some existing user authentication schemes. PMID:26184224

  1. A User Authentication Scheme Based on Elliptic Curves Cryptography for Wireless Ad Hoc Networks

    PubMed Central

    Chen, Huifang; Ge, Linlin; Xie, Lei

    2015-01-01

    The feature of non-infrastructure support in a wireless ad hoc network (WANET) makes it suffer from various attacks. Moreover, user authentication is the first safety barrier in a network. A mutual trust is achieved by a protocol which enables communicating parties to authenticate each other at the same time and to exchange session keys. For the resource-constrained WANET, an efficient and lightweight user authentication scheme is necessary. In this paper, we propose a user authentication scheme based on the self-certified public key system and elliptic curves cryptography for a WANET. Using the proposed scheme, an efficient two-way user authentication and secure session key agreement can be achieved. Security analysis shows that our proposed scheme is resilient to common known attacks. In addition, the performance analysis shows that our proposed scheme performs similar or better compared with some existing user authentication schemes. PMID:26184224

  2. Post Hoc Analysis of the PATRICIA Randomized Trial of the Efficacy of Human Papillomavirus Type 16 (HPV-16)/HPV-18 AS04-Adjuvanted Vaccine against Incident and Persistent Infection with Nonvaccine Oncogenic HPV Types Using an Alternative Multiplex Type-Specific PCR Assay for HPV DNA

    PubMed Central

    Colau, Brigitte; Wheeler, Cosette M.; Naud, Paulo; Garland, Suzanne; Quint, Wim; Chow, Song-Nan; Salmerón, Jorge; Lehtinen, Matti; Del Rosario-Raymundo, M. Rowena; Paavonen, Jorma; Teixeira, Júlio C.; Germar, Maria Julieta; Peters, Klaus; Skinner, S. Rachel; Limson, Genara; Castellsagué, Xavier; Poppe, Willy A. J.; Ramjattan, Brian; Klein, Terry D.; Schwarz, Tino F.; Chatterjee, Archana; Tjalma, Wiebren A. A.; Diaz-Mitoma, Francisco; Lewis, David J. M.; Harper, Diane M.; Molijn, Anco; van Doorn, Leen-Jan; David, Marie-Pierre; Dubin, Gary

    2014-01-01

    The efficacy of the human papillomavirus type 16 (HPV-16)/HPV-18 AS04-adjuvanted vaccine against cervical infections with HPV in the Papilloma Trial against Cancer in Young Adults (PATRICIA) was evaluated using a combination of the broad-spectrum L1-based SPF10 PCR-DNA enzyme immunoassay (DEIA)/line probe assay (LiPA25) system with type-specific PCRs for HPV-16 and -18. Broad-spectrum PCR assays may underestimate the presence of HPV genotypes present at relatively low concentrations in multiple infections, due to competition between genotypes. Therefore, samples were retrospectively reanalyzed using a testing algorithm incorporating the SPF10 PCR-DEIA/LiPA25 plus a novel E6-based multiplex type-specific PCR and reverse hybridization assay (MPTS12 RHA), which permits detection of a panel of nine oncogenic HPV genotypes (types 16, 18, 31, 33, 35, 45, 52, 58, and 59). For the vaccine against HPV types 16 and 18, there was no major impact on estimates of vaccine efficacy (VE) for incident or 6-month or 12-month persistent infections when the MPTS12 RHA was included in the testing algorithm versus estimates with the protocol-specified algorithm. However, the alternative testing algorithm showed greater sensitivity than the protocol-specified algorithm for detection of some nonvaccine oncogenic HPV types. More cases were gained in the control group than in the vaccine group, leading to higher point estimates of VE for 6-month and 12-month persistent infections for the nonvaccine oncogenic types included in the MPTS12 RHA assay (types 31, 33, 35, 45, 52, 58, and 59). This post hoc analysis indicates that the per-protocol testing algorithm used in PATRICIA underestimated the VE against some nonvaccine oncogenic HPV types and that the choice of the HPV DNA testing methodology is important for the evaluation of VE in clinical trials. (This study has been registered at ClinicalTrials.gov under registration no. NCT00122681.) PMID:25540273

  3. Post hoc analysis of the PATRICIA randomized trial of the efficacy of human papillomavirus type 16 (HPV-16)/HPV-18 AS04-adjuvanted vaccine against incident and persistent infection with nonvaccine oncogenic HPV types using an alternative multiplex type-specific PCR assay for HPV DNA.

    PubMed

    Struyf, Frank; Colau, Brigitte; Wheeler, Cosette M; Naud, Paulo; Garland, Suzanne; Quint, Wim; Chow, Song-Nan; Salmerón, Jorge; Lehtinen, Matti; Del Rosario-Raymundo, M Rowena; Paavonen, Jorma; Teixeira, Júlio C; Germar, Maria Julieta; Peters, Klaus; Skinner, S Rachel; Limson, Genara; Castellsagué, Xavier; Poppe, Willy A J; Ramjattan, Brian; Klein, Terry D; Schwarz, Tino F; Chatterjee, Archana; Tjalma, Wiebren A A; Diaz-Mitoma, Francisco; Lewis, David J M; Harper, Diane M; Molijn, Anco; van Doorn, Leen-Jan; David, Marie-Pierre; Dubin, Gary

    2015-02-01

    The efficacy of the human papillomavirus type 16 (HPV-16)/HPV-18 AS04-adjuvanted vaccine against cervical infections with HPV in the Papilloma Trial against Cancer in Young Adults (PATRICIA) was evaluated using a combination of the broad-spectrum L1-based SPF10 PCR-DNA enzyme immunoassay (DEIA)/line probe assay (LiPA25) system with type-specific PCRs for HPV-16 and -18. Broad-spectrum PCR assays may underestimate the presence of HPV genotypes present at relatively low concentrations in multiple infections, due to competition between genotypes. Therefore, samples were retrospectively reanalyzed using a testing algorithm incorporating the SPF10 PCR-DEIA/LiPA25 plus a novel E6-based multiplex type-specific PCR and reverse hybridization assay (MPTS12 RHA), which permits detection of a panel of nine oncogenic HPV genotypes (types 16, 18, 31, 33, 35, 45, 52, 58, and 59). For the vaccine against HPV types 16 and 18, there was no major impact on estimates of vaccine efficacy (VE) for incident or 6-month or 12-month persistent infections when the MPTS12 RHA was included in the testing algorithm versus estimates with the protocol-specified algorithm. However, the alternative testing algorithm showed greater sensitivity than the protocol-specified algorithm for detection of some nonvaccine oncogenic HPV types. More cases were gained in the control group than in the vaccine group, leading to higher point estimates of VE for 6-month and 12-month persistent infections for the nonvaccine oncogenic types included in the MPTS12 RHA assay (types 31, 33, 35, 45, 52, 58, and 59). This post hoc analysis indicates that the per-protocol testing algorithm used in PATRICIA underestimated the VE against some nonvaccine oncogenic HPV types and that the choice of the HPV DNA testing methodology is important for the evaluation of VE in clinical trials. (This study has been registered at ClinicalTrials.gov under registration no. NCT00122681.). PMID:25540273

  4. On Trust Evaluation in Mobile Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Nguyen, Dang Quan; Lamont, Louise; Mason, Peter C.

    Trust has been considered as a social relationship between two individuals in human society. But, as computer science and networking have succeeded in using computers to automate many tasks, the concept of trust can be generalized to cover the reliability and relationships of non-human interaction, such as, for example, information gathering and data routing. This paper investigates the evaluation of trust in the context of ad hoc networks. Nodes evaluate each other’s behaviour based on observables. A node then decides whether to trust another node to have certain innate abilities. We show how accurate such an evaluation could be. We also provide the minimum number of observations required to obtain an accurate evaluation, a result that indicates that observation-based trust in ad hoc networks will remain a challenging problem. The impact of making networking decisions using trust evaluation on the network connectivity is also examined. In this manner, quantitative decisions can be made concerning trust-based routing with the knowledge of the potential impact on connectivity.

  5. Intelligent routing protocol for ad hoc wireless network

    NASA Astrophysics Data System (ADS)

    Peng, Chaorong; Chen, Chang Wen

    2006-05-01

    A novel routing scheme for mobile ad hoc networks (MANETs), which combines hybrid and multi-inter-routing path properties with a distributed topology discovery route mechanism using control agents is proposed in this paper. In recent years, a variety of hybrid routing protocols for Mobile Ad hoc wireless networks (MANETs) have been developed. Which is proactively maintains routing information for a local neighborhood, while reactively acquiring routes to destinations beyond the global. The hybrid protocol reduces routing discovery latency and the end-to-end delay by providing high connectivity without requiring much of the scarce network capacity. On the other side the hybrid routing protocols in MANETs likes Zone Routing Protocol still need route "re-discover" time when a route between zones link break. Sine the topology update information needs to be broadcast routing request on local zone. Due to this delay, the routing protocol may not be applicable for real-time data and multimedia communication. We utilize the advantages of a clustering organization and multi-routing path in routing protocol to achieve several goals at the same time. Firstly, IRP efficiently saves network bandwidth and reduces route reconstruction time when a routing path fails. The IRP protocol does not require global periodic routing advertisements, local control agents will automatically monitor and repair broke links. Secondly, it efficiently reduces congestion and traffic "bottlenecks" for ClusterHeads in clustering network. Thirdly, it reduces significant overheads associated with maintaining clusters. Fourthly, it improves clusters stability due to dynamic topology changing frequently. In this paper, we present the Intelligent Routing Protocol. First, we discuss the problem of routing in ad hoc networks and the motivation of IRP. We describe the hierarchical architecture of IRP. We describe the routing process and illustrate it with an example. Further, we describe the control manage

  6. Implementation and performance evaluation of mobile ad hoc network for Emergency Telemedicine System in disaster areas.

    PubMed

    Kim, J C; Kim, D Y; Jung, S M; Lee, M H; Kim, K S; Lee, C K; Nah, J Y; Lee, S H; Kim, J H; Choi, W J; Yoo, S K

    2009-01-01

    So far we have developed Emergency Telemedicine System (ETS) which is a robust system using heterogeneous networks. In disaster areas, however, ETS cannot be used if the primary network channel is disabled due to damages on the network infrastructures. Thus we designed network management software for disaster communication network by combination of Mobile Ad hoc Network (MANET) and Wireless LAN (WLAN). This software maintains routes to a Backbone Gateway Node in dynamic network topologies. In this paper, we introduce the proposed disaster communication network with management software, and evaluate its performance using ETS between Medical Center and simulated disaster areas. We also present the results of network performance analysis which identifies the possibility of actual Telemedicine Service in disaster areas via MANET and mobile network (e.g. HSDPA, WiBro). PMID:19964544

  7. Topology Control in Large-Scale High Dynamic Mobile Ad-Hoc Networks

    NASA Astrophysics Data System (ADS)

    El-Habbal, Mohamed; Rückert, Ulrich; Witkowski, Ulf

    We present our contribution in projects related to ad-hoc networking using different routing protocols and hardware platforms, showing our results and new solutions regarding topology control and routing protocols. We mainly focus on our work in the GUARDIANS EU-project, where as a main disaster scenario a large industrial warehouse on fire is assumed. The paper presents the simulation results for the routing protocols ACR, DSR and EDSR, as well as the implementation of down-scaled demos for supporting the autonomous team of robots as well as the human squad team with robust communication coverage. Various hardware platforms were used in the demos for distance measurement, based on laser range finder and radio communication with time of flight analysis.

  8. Opportunistic Channel Scheduling for Ad Hoc Networks with Queue Stability

    NASA Astrophysics Data System (ADS)

    Dong, Lei; Wang, Yongchao

    2015-03-01

    In this paper, a distributed opportunistic channel access strategy in ad hoc network is proposed. We consider the multiple sources contend for the transmission opportunity, the winner source decides to transmit or restart contention based on the current channel condition. Owing to real data assumption at all links, the decision still needs to consider the stability of the queues. We formulate the channel opportunistic scheduling as a constrained optimization problem which maximizes the system average throughput with the constraints that the queues of all links are stable. The proposed optimization model is solved by Lyapunov stability in queueing theory. The successive channel access problem is decoupled into single optimal stopping problem at every frame and solved with Lyapunov algorithm. The threshold for every frame is different, and it is derived based on the instantaneous queue information. Finally, computer simulations are conducted to demonstrate the validity of the proposed strategy.

  9. Indoor Positioning - An Ad-Hoc Positioning System

    NASA Astrophysics Data System (ADS)

    Mautz, Rainer

    2008-06-01

    The aim of this paper is to discuss the development of an automatic, low-cost system that exploits current or near future wireless communications technology to enable continuous tracking of the location of devices in all environments. The development of such a wireless sensor network involves system design, digital signal processing, protocol development, extraction of ranges and localisation. This paper focuses on the user requirements, system architecture and network positioning. The user requirements are presented with a focus on applications in geodesy. A high level strategy for the positioning function is presented based on an ad-hoc geodetic network positioning method including issues of accuracy, quality and reliability of the node positions. Results show that it is possible to achieve a position deviation that is of the size of the ranging error.

  10. Ad hoc committee on global climate issues: Annual report

    USGS Publications Warehouse

    Gerhard, L.C.; Hanson, B.M.B.

    2000-01-01

    The AAPG Ad Hoc Committee on Global Climate Issues has studied the supposition of human-induced climate change since the committee's inception in January 1998. This paper details the progress and findings of the committee through June 1999. At that time there had been essentially no geologic input into the global climate change debate. The following statements reflect the current state of climate knowledge from the geologic perspective as interpreted by the majority of the committee membership. The committee recognizes that new data could change its conclusions. The earth's climate is constantly changing owing to natural variability in earth processes. Natural climate variability over recent geological time is greater than reasonable estimates of potential human-induced greenhouse gas changes. Because no tool is available to test the supposition of human-induced climate change and the range of natural variability is so great, there is no discernible human influence on global climate at this time.

  11. Realistic Mobility Modeling for Vehicular Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Akay, Hilal; Tugcu, Tuna

    2009-08-01

    Simulations used for evaluating the performance of routing protocols for Vehicular Ad Hoc Networks (VANET) are mostly based on random mobility and fail to consider individual behaviors of the vehicles. Unrealistic assumptions about mobility produce misleading results about the behavior of routing protocols in real deployments. In this paper, a realistic mobility modeling tool, Mobility for Vehicles (MOVE), which considers the basic mobility behaviors of vehicles, is proposed for a more accurate evaluation. The proposed model is tested against the Random Waypoint (RWP) model using AODV and OLSR protocols. The results show that the mobility model significantly affects the number of nodes within the transmission range of a node, the volume of control traffic, and the number of collisions. It is shown that number of intersections, grid size, and node density are important parameters when dealing with VANET performance.

  12. Topology for efficient information dissemination in ad-hoc networking

    NASA Technical Reports Server (NTRS)

    Jennings, E.; Okino, C. M.

    2002-01-01

    In this paper, we explore the information dissemination problem in ad-hoc wirless networks. First, we analyze the probability of successful broadcast, assuming: the nodes are uniformly distributed, the available area has a lower bould relative to the total number of nodes, and there is zero knowledge of the overall topology of the network. By showing that the probability of such events is small, we are motivated to extract good graph topologies to minimize the overall transmissions. Three algorithms are used to generate topologies of the network with guaranteed connectivity. These are the minimum radius graph, the relative neighborhood graph and the minimum spanning tree. Our simulation shows that the relative neighborhood graph has certain good graph properties, which makes it suitable for efficient information dissemination.

  13. Maximizing the Effective Lifetime of Mobile Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Hossain, M. Julius; Dewan, M. Ali Akber; Chae, Oksam

    This paper presents a new routing approach to extend the effective lifetime of mobile ad hoc networks (MANET) considering both residual battery energy of the participating nodes and routing cost. As the nodes in ad hoc networks are limited in power, a power failure occurs if a node has insufficient remaining energy to send, receive or forward a message. So, it is important to minimize the energy expenditure as well as to balance the remaining battery power among the nodes. Cost effective routing algorithms attempt to minimize the total power needed to transmit a packet which causes a large number of nodes to loose energy quickly and die. On the other hand, lifetime prediction based routing algorithms try to balance the remaining energies among the nodes in the networks and ignore the transmission cost. These approaches extend the lifetime of first few individual nodes. But as nodes spend more energy for packet transfer, power failures occurs, within short interval resulting more number of total dead node earlier. This reduces the effective lifetime of the network, as at this stage successful communication is not possible due to the lack of forwarding node. The proposed method keeps the transmission power in modest range and at the same time tries to reduce the variance of the residual energy of the nodes more effectively to obtain the highest useful lifetime of the networks in the long run. Nonetheless, movement of nodes frequently creates network topology changes via link breaks and link creation and thus effects on the stability of the network. So, the pattern of the node movement is also incorporated in our route selection procedure.

  14. 32 CFR 2800.7 - Designation of chairperson for Ad Hoc Committees.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 32 National Defense 6 2011-07-01 2011-07-01 false Designation of chairperson for Ad Hoc Committees... VICE PRESIDENT OF THE UNITED STATES SECURITY PROCEDURES § 2800.7 Designation of chairperson for Ad Hoc Committees. The Counsel to the Vice President is designated as the responsible official to chair Ad...

  15. A Token Ring Protocol for Dynamic Ad-hoc Wireless Environments

    SciTech Connect

    Top, P; Kohlhepp, V; Dowla, F

    2005-09-30

    A wireless ad-hoc networking protocol is presented. The protocol is designed to be flexible, easy to use and adaptable to a wide variety of potential applications. The primary considerations in design are small code size, guaranteed bandwidth access, limited delay, and error resilience in a highly dynamic ad-hoc environment. These considerations are achieved through the use of token ring protocol.

  16. 32 CFR 2800.7 - Designation of chairperson for Ad Hoc Committees.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 32 National Defense 6 2010-07-01 2010-07-01 false Designation of chairperson for Ad Hoc Committees... VICE PRESIDENT OF THE UNITED STATES SECURITY PROCEDURES § 2800.7 Designation of chairperson for Ad Hoc Committees. The Counsel to the Vice President is designated as the responsible official to chair Ad...

  17. 32 CFR 2800.7 - Designation of chairperson for Ad Hoc Committees.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 32 National Defense 6 2012-07-01 2012-07-01 false Designation of chairperson for Ad Hoc Committees... VICE PRESIDENT OF THE UNITED STATES SECURITY PROCEDURES § 2800.7 Designation of chairperson for Ad Hoc Committees. The Counsel to the Vice President is designated as the responsible official to chair Ad...

  18. Typicality Mediates Performance during Category Verification in Both Ad-Hoc and Well-Defined Categories

    ERIC Educational Resources Information Center

    Sandberg, Chaleece; Sebastian, Rajani; Kiran, Swathi

    2012-01-01

    Background: The typicality effect is present in neurologically intact populations for natural, ad-hoc, and well-defined categories. Although sparse, there is evidence of typicality effects in persons with chronic stroke aphasia for natural and ad-hoc categories. However, it is unknown exactly what influences the typicality effect in this…

  19. 32 CFR 2800.7 - Designation of chairperson for Ad Hoc Committees.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 32 National Defense 6 2014-07-01 2014-07-01 false Designation of chairperson for Ad Hoc Committees... VICE PRESIDENT OF THE UNITED STATES SECURITY PROCEDURES § 2800.7 Designation of chairperson for Ad Hoc Committees. The Counsel to the Vice President is designated as the responsible official to chair Ad...

  20. 32 CFR 2800.7 - Designation of chairperson for Ad Hoc Committees.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 32 National Defense 6 2013-07-01 2013-07-01 false Designation of chairperson for Ad Hoc Committees... VICE PRESIDENT OF THE UNITED STATES SECURITY PROCEDURES § 2800.7 Designation of chairperson for Ad Hoc Committees. The Counsel to the Vice President is designated as the responsible official to chair Ad...

  1. Detecting and isolating malicious nodes in wireless ad hoc networks

    NASA Astrophysics Data System (ADS)

    Li, Fanzhi; Jassim, Sabah

    2007-04-01

    Malicious nodes can seriously impair the performance of wireless ad hoc networks as a result of different actions such as packet dropping. Secure routes are shortest paths on which every node on the route is trusted even if unknown. Secure route discovery requires the adoption of mechanisms of associating trust to nodes. Most existing secure route discovery mechanisms rely on shared keys and digital signature. In the absence of central nodes that act as certification authority, such protocols suffer from heavy computational burden and are vulnerable to malicious attacks. In this paper we shall review existing techniques for secure routing and propose to complement route finding with creditability scores. Each node would have a credit list for its neighbors. Each node monitors its neighbors' pattern of delivering packets and regularly credits are reviewed and updated accordingly. Unlike most existing schemes the focus of our work is based on post route discovery stage, i.e. when packets are transmitted on discovered routes. The level of trust in any route will be based on the credits associated with the neighbors belonging to the discovered route. We shall evaluate the performance of the proposed scheme by modifying our simulation system so that each node has a dynamic changing "credit list" for its neighbors' behavior. We shall conduct a series of simulations with and without the proposed scheme and compare the results. We will demonstrate that the proposed mechanism is capable of isolating malicious nodes and thereby counteracting black hole attacks.

  2. Managing performance of DB2 Ad Hoc Reports

    SciTech Connect

    Chow, A.

    1994-02-01

    The DB2 financial reporting systems at Westinghouse Savannah River Company consists of 212 standardized reports that over 1034 users have accessed in 1993 to generate their reports. Each report has a range of selection criteria that the users can specify. Depending on the selection criteria, a report can access from a few rows to millions of rows of data. When this new DB2 system went into production in 1992, the CPU was at 100% utilization. From the beginning, ad hoc reports had a backlog of 4--5 days. Since DB2 was a new DBMS, most people blamed the poor report turn around times on DB2 as an inefficient DBMS and on a shortage of CPU cycles. Since we are unable to purchase a more powerful CPU, the only option left to us was to improve report turn around was system and application performance tuning. This document presents our efforts in these areas. Education of users in report submission was a starting point. And as to index tuning techniques that were applied, we created more friendly indexes, used clustering indexes, and used a reorganizing mechanism. A more efficient SQL was written which saved a lot of money.

  3. Algorithmic aspects of topology control problems for ad hoc networks

    SciTech Connect

    Liu, R.; Lloyd, E. L.; Marathe, M. V.; Ramanathan, R.; Ravi, S. S.

    2002-01-01

    Topology control problems are concerned with the assignment of power values to nodes of an ad hoc network so that the power assignment leads to a graph topology satisfying some specified properties. This paper considers such problems under several optimization objectives, including minimizing the maximum power and minimizing the total power. A general approach leading to a polynomial algorithm is presented for minimizing maximum power for a class of graph properties, called monotone properties. The difficulty of generalizing the approach to properties that are not monoione is pointed out. Problems involving the minimization of total power are known to be NP-complete even for simple graph properties. A general approach that leads to an approximation algorithm for minimizing the total power for some monotone properties is presented. Using this approach, a new approximation algorithm for the problem of minimizing the total power for obtaining a 2-node-connected graph is obtained. It is shown that this algorithm provides a constant performance guarantee. Experimental results from an implementation of the approximation algorithm are also presented.

  4. Load-aware Flooding for Streaming over Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Utsu, Keisuke; Ishii, Hiroshi

    This paper discusses the streaming of high rate media such as video or audio information over ad hoc networks in disaster situations or for temporary events when it is difficult to use fixed infrastructure. The conventional simple flooding is not applicable for this application because it generates a large number of redundant rebroadcast and heavy traffic load to the network. To restrain redundant rebroadcast messages, several methods have been proposed. But since those studies do not take into account the actual load condition at each node that will affect network efficiency, they cannot achieve both ensuring the high message reachability and reducing redundant rebroadcast. In this paper, we propose two novel load-aware flooding methods using the MAC transmission queue information at each node to make the decision about whether rebroadcast messages should be sent or not. Through network simulations, we evaluate and show the effectiveness of our proposals. The result shows that our proposals achieve both ensuring high message reachability and restraint of redundant rebroadcast comparing with existing methods.

  5. Design of the next generation cognitive mobile ad hoc networks

    NASA Astrophysics Data System (ADS)

    Amjad, Ali; Wang, Huiqiang; Chen, Xiaoming

    Cognition capability has been seen by researchers as the way forward for the design of next generation of Mobile Ad Hoc Networks (MANETs). The reason why a cognitive paradigm would be more suited to a MANET is because MANETs are highly dynamic networks. The topology may change very frequently during the operation of a MANET. Traffic patterns in MANETs can vary from time to time depending on the need of the users. The size of a MANET and node density is also very dynamic and may change without any predictable pattern. In a MANET environment, most of these parameters may change very rapidly and keeping track of them manually would be very difficult. Previous studies have shown that the performance of a certain routing approach in MANETs is dependent on the size of the network and node density. The choice of whether to use a reactive or proactive routing approach comes down to the network size parameter. Static or offline approaches to fine tune a MANET to achieve certain performance goals is hence not very productive as a lot of these parameters keep changing during the course of operation of MANETs. Similarly, the performance of MANETs would improve greatly if the MAC layer entity could operate in a more flexible manner. In this paper we propose a cognitive MANET design that will ensure that all these dynamic parameters are automatically monitored and decisions are based on the current status of these parameters.

  6. Random Time Identity Based Firewall In Mobile Ad hoc Networks

    NASA Astrophysics Data System (ADS)

    Suman, Patel, R. B.; Singh, Parvinder

    2010-11-01

    A mobile ad hoc network (MANET) is a self-organizing network of mobile routers and associated hosts connected by wireless links. MANETs are highly flexible and adaptable but at the same time are highly prone to security risks due to the open medium, dynamically changing network topology, cooperative algorithms, and lack of centralized control. Firewall is an effective means of protecting a local network from network-based security threats and forms a key component in MANET security architecture. This paper presents a review of firewall implementation techniques in MANETs and their relative merits and demerits. A new approach is proposed to select MANET nodes at random for firewall implementation. This approach randomly select a new node as firewall after fixed time and based on critical value of certain parameters like power backup. This approach effectively balances power and resource utilization of entire MANET because responsibility of implementing firewall is equally shared among all the nodes. At the same time it ensures improved security for MANETs from outside attacks as intruder will not be able to find out the entry point in MANET due to the random selection of nodes for firewall implementation.

  7. Z306 molecular contamination ad hoc committee results

    NASA Technical Reports Server (NTRS)

    Golden, Johnny L.

    1992-01-01

    LDEF external surfaces which did not receive significant amounts of atomic oxygen were observed to be coated with a brown contamination, apparently the result of a condensed organic residue darkened due to UV radiation exposure. During the initial Materials Special Investigation Group (MSIG) Meeting after LDEF deintegration, held in Seattle - July 1990, this organic contamination was the subject of much discussion. The amount of contamination was thought to be significant and its source was immediately believed to be the Z306 black thermal control coating used to coat the entire inner surface of LDEF. Due to the size of the structure, it was not feasible to bake-out the coating. However, initial data on the contamination film was confusing in that significant amounts of silicon was observed by several different researchers. Silicon (from silicone) was not expected to be a potential outgassing product of the Z306 polyurethane coating. To investigate the connection between external contamination and the interior paint, a MSIG ad hoc committee was formed.

  8. Performance Improvement in Geographic Routing for Vehicular Ad Hoc Networks

    PubMed Central

    Kaiwartya, Omprakash; Kumar, Sushil; Lobiyal, D. K.; Abdullah, Abdul Hanan; Hassan, Ahmed Nazar

    2014-01-01

    Geographic routing is one of the most investigated themes by researchers for reliable and efficient dissemination of information in Vehicular Ad Hoc Networks (VANETs). Recently, different Geographic Distance Routing (GEDIR) protocols have been suggested in the literature. These protocols focus on reducing the forwarding region towards destination to select the Next Hop Vehicles (NHV). Most of these protocols suffer from the problem of elevated one-hop link disconnection, high end-to-end delay and low throughput even at normal vehicle speed in high vehicle density environment. This paper proposes a Geographic Distance Routing protocol based on Segment vehicle, Link quality and Degree of connectivity (SLD-GEDIR). The protocol selects a reliable NHV using the criteria segment vehicles, one-hop link quality and degree of connectivity. The proposed protocol has been simulated in NS-2 and its performance has been compared with the state-of-the-art protocols: P-GEDIR, J-GEDIR and V-GEDIR. The empirical results clearly reveal that SLD-GEDIR has lower link disconnection and end-to-end delay, and higher throughput as compared to the state-of-the-art protocols. It should be noted that the performance of the proposed protocol is preserved irrespective of vehicle density and speed. PMID:25429415

  9. Resistivity tomography of Pointe du Hoc cliffs for stability assessment

    NASA Astrophysics Data System (ADS)

    Udphuay, S.; Everett, M. E.; Warden, R.

    2008-12-01

    Pointe du Hoc WWII battlefield overlooking the English Channel in western Normandy, France, is an important cultural resource, being an integral component of the June 6 1944 D-Day invasion. Two major buildings, the forward observation post (OP) and Col. Rudder's command post (RCP), are now perched perilously close to the cliff's edge owing to six decades of cliff retreat. Geophysical surveys were carried out in March 2008 to investigate the risk of cliff failure and to inform possible geotechnical remediation strategies with a final goal toward re-opening the observation post that is now closed to visitors. The geophysical surveying is accomplished by high-resolution resistivity tomography, conducted in extreme topography and in the midst of dense cultural clutter. The results of the OP tomography indicate that the highest mass movement hazard is associated with the marine caverns at the base of the cliff at the point of strongest wave attack. These caverns occupy the future site of a sea arch which will threaten the OP building. There is a high probability of a soil wedge failure on the east facing cliff edge close to the OP building. Such a failure could damage or destroy the building. The possibility of a sudden catastrophic failure along any one of these fractures cannot be ruled out. The greatest risk at the RCP site, which is under less immediate threat, is associated with soil wedge failures at the top of the cliffs.

  10. A Multi-User Game-Theoretical Multipath Routing Protocol to Send Video-Warning Messages over Mobile Ad Hoc Networks

    PubMed Central

    Mezher, Ahmad Mohamad; Igartua, Mónica Aguilar; de la Cruz Llopis, Luis J.; Segarra, Esteve Pallarès; Tripp-Barba, Carolina; Urquiza-Aguiar, Luis; Forné, Jordi; Gargallo, Emilio Sanvicente

    2015-01-01

    The prevention of accidents is one of the most important goals of ad hoc networks in smart cities. When an accident happens, dynamic sensors (e.g., citizens with smart phones or tablets, smart vehicles and buses, etc.) could shoot a video clip of the accident and send it through the ad hoc network. With a video message, the level of seriousness of the accident could be much better evaluated by the authorities (e.g., health care units, police and ambulance drivers) rather than with just a simple text message. Besides, other citizens would be rapidly aware of the incident. In this way, smart dynamic sensors could participate in reporting a situation in the city using the ad hoc network so it would be possible to have a quick reaction warning citizens and emergency units. The deployment of an efficient routing protocol to manage video-warning messages in mobile Ad hoc Networks (MANETs) has important benefits by allowing a fast warning of the incident, which potentially can save lives. To contribute with this goal, we propose a multipath routing protocol to provide video-warning messages in MANETs using a novel game-theoretical approach. As a base for our work, we start from our previous work, where a 2-players game-theoretical routing protocol was proposed to provide video-streaming services over MANETs. In this article, we further generalize the analysis made for a general number of N players in the MANET. Simulations have been carried out to show the benefits of our proposal, taking into account the mobility of the nodes and the presence of interfering traffic.Finally, we also have tested our approach in a vehicular ad hoc network as an incipient start point to develop a novel proposal specifically designed for VANETs. PMID:25897496

  11. A Multi-User Game-Theoretical Multipath Routing Protocol to Send Video-Warning Messages over Mobile Ad Hoc Networks.

    PubMed

    Mezher, Ahmad Mohamad; Igartua, Mónica Aguilar; de la Cruz Llopis, Luis J; Pallarès Segarra, Esteve; Tripp-Barba, Carolina; Urquiza-Aguiar, Luis; Forné, Jordi; Sanvicente Gargallo, Emilio

    2015-01-01

    The prevention of accidents is one of the most important goals of ad hoc networks in smart cities. When an accident happens, dynamic sensors (e.g., citizens with smart phones or tablets, smart vehicles and buses, etc.) could shoot a video clip of the accident and send it through the ad hoc network. With a video message, the level of seriousness of the accident could be much better evaluated by the authorities (e.g., health care units, police and ambulance drivers) rather than with just a simple text message. Besides, other citizens would be rapidly aware of the incident. In this way, smart dynamic sensors could participate in reporting a situation in the city using the ad hoc network so it would be possible to have a quick reaction warning citizens and emergency units. The deployment of an efficient routing protocol to manage video-warning messages in mobile Ad hoc Networks (MANETs) has important benefits by allowing a fast warning of the incident, which potentially can save lives. To contribute with this goal, we propose a multipath routing protocol to provide video-warning messages in MANETs using a novel game-theoretical approach. As a base for our work, we start from our previous work, where a 2-players game-theoretical routing protocol was proposed to provide video-streaming services over MANETs. In this article, we further generalize the analysis made for a general number of N players in the MANET. Simulations have been carried out to show the benefits of our proposal, taking into account the mobility of the nodes and the presence of interfering traffic. Finally, we also have tested our approach in a vehicular ad hoc network as an incipient start point to develop a novel proposal specifically designed for VANETs. PMID:25897496

  12. 75 FR 33838 - NASA Advisory Council; Ad-Hoc Task Force on Planetary Defense; Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-06-15

    ... Parham, Exploration Systems Mission Directorate, National Aeronautics and Space Administration... SPACE ADMINISTRATION NASA Advisory Council; Ad-Hoc Task Force on Planetary Defense; Meeting AGENCY: National Aeronautics and Space Administration. ACTION: Notice of Meeting. SUMMARY: In accordance with...

  13. A Group Based Key Sharing and Management Algorithm for Vehicular Ad Hoc Networks

    PubMed Central

    Moharram, Mohammed Morsi; Azam, Farzana

    2014-01-01

    Vehicular ad hoc networks (VANETs) are one special type of ad hoc networks that involves vehicles on roads. Typically like ad hoc networks, broadcast approach is used for data dissemination. Blind broadcast to each and every node results in exchange of useless and irrelevant messages and hence creates an overhead. Unicasting is not preferred in ad-hoc networks due to the dynamic topology and the resource requirements as compared to broadcasting. Simple broadcasting techniques create several problems on privacy, disturbance, and resource utilization. In this paper, we propose media mixing algorithm to decide what information should be provided to each user and how to provide such information. Results obtained through simulation show that fewer number of keys are needed to share compared to simple broadcasting. Privacy is also enhanced through this approach. PMID:24587749

  14. Ad-hoc percutaneous coronary intervention and staged percutaneous coronary intervention.

    PubMed

    Rahman, Z; Paul, G K; Choudhury, A K

    2011-10-01

    Percutaneous coronary intervention (PCI) is a catheter based procedure where a catheter system is introduced through a systemic artery under local anesthesia in a stenotic coronary artery by controlled inflation of a distensible balloon. At early period, PCI was done in a separate session following coronary angiogram (Staged PCI) and it was more costly and hospital stay was long. As the expertization and laboratory facilities improved, the health care providers think about cost, hospital stay and patient convenience. So, to reduce the cost and patient preferred more PCI being done immediately following diagnostic catheterization (Ad-hoc PCI). Subsequently this Ad-hoc procedure becomes popular and now most of the PCI are Ad-hoc PCI worldwide. Rate of combined procedure (Ad-hoc) progressively increased from 54% in 1990 to 88% in 2000 with a significant decrease in rate of complications. In the initial study of Ad-hoc PCI suggested that Ad-hoc PCI should be done in selected group of patients as there was some potential risk factors (e.g. Multivessel diseases, unstable angina, aortic valve disease, and recent infarction or thrombolytic therapy) for Ad-hoc procedure and some (e.g. Older age, multivessel PTCA and complex lesion PTCA) for staged procedure. But recent studies showed that no significant difference in respect of safety and efficacy between Ad-hoc and staged PCI. Previous studies, in the era of balloon angioplasty from 1985 to 1995, Haraphonges et al. (1988), Rozenman et al. (1995) and Kimmel et al. (1997) suggested that an ad hoc approach is safe, with potentially more complications in patients with unstable angina pectoris or other high-risk factors. However, these reports have been limited to observational studies representing single institution experiences with small samples and inclusion of patients who underwent emergency PCI procedures. In Bangladesh a prospective observational study was done among 120 patients to compare the outcome of Ad-hoc and

  15. Algorithmic, LOCS and HOCS (chemistry) exam questions: performance and attitudes of college students

    NASA Astrophysics Data System (ADS)

    Zoller, Uri

    2002-02-01

    The performance of freshmen biology and physics-mathematics majors and chemistry majors as well as pre- and in-service chemistry teachers in two Israeli universities on algorithmic (ALG), lower-order cognitive skills (LOCS), and higher-order cognitive skills (HOCS) chemistry exam questions were studied. The driving force for the study was an interest in moving science and chemistry instruction from an algorithmic and factual recall orientation dominated by LOCS, to a decision-making, problem-solving and critical system thinking approach, dominated by HOCS. College students' responses to the specially designed ALG, LOCS and HOCS chemistry exam questions were scored and analysed for differences and correlation between the performance means within and across universities by the questions' category. This was followed by a combined student interview - 'speaking aloud' problem solving session for assessing the thinking processes involved in solving these types of questions and the students' attitudes towards them. The main findings were: (1) students in both universities performed consistently in each of the three categories in the order of ALG > LOCS > HOCS; their 'ideological' preference, was HOCS > algorithmic/LOCS, - referred to as 'computational questions', but their pragmatic preference was the reverse; (2) success on algorithmic/LOCS does not imply success on HOCS questions; algorithmic questions constitute a category on its own as far as students success in solving them is concerned. Our study and its results support the effort being made, worldwide, to integrate HOCS-fostering teaching and assessment strategies and, to develop HOCS-oriented science-technology-environment-society (STES)-type curricula within science and chemistry education.

  16. Characterizing the Interaction Between Routing and MAC Protocols in Ad-Hoc Networks

    SciTech Connect

    Barrett, C. L.; Drozda, M.; Marathe, A.; Marathe, M. V.

    2002-01-01

    We empirically study the effect of mobility on the performance of protocols designed for wireless ad-hoc networks. An important objective is to study the interaction of the Routing and MAC layer protocols under different mobility parameters. We use three basic mobility models: grid mobility model, random waypoint model, and exponential correlated random model. The performance of protocols is measured in terms of (i) latency, (ii) throughput, (iii) number of packets received, (iv) long term fairness and (v) number of control packets at the MAC and routing layer level. Three different commonly studied routing protocols are used: AODV, DSR and LAR1. Similarly three well known MAC protocols are used: MACA, 802.1 1 and CSMA. Our main contribution is simulation based experiments coupled with rigorous statistical analysis to characterize the interaction of MAC layer protocols with routing layer protocols in ad-hoc networks. From the results, we can conclude the following: e No single MAC or Routing protocol dominated the other protocols in their class. Probably more interestingly, no MAURouting protocol combination was better than other combinations over all scenarios and response variables. 0 In general, it is not meaningful to speak about a MAC or a routing protocol in isolation. Presence of interaction leads to trade-offs between the amount of control packets generated by each layer. The results raise the possibility of improving the performance of a particular MAC layer protocol by using a cleverly designed routing protocol or vice-versa. Thus in order to improve the performanceof a communication network, it is important to study the entire protocol stack as a single algorithmic construct; optimizing individual layers in the seven layer OS1 stack will not yield performance improvements beyond a point. A methodological contribution of this paper is the use of statistical methods such as analysis of variance (ANOVA), to characterize the interaction between the protocols

  17. Design of multilevel heterogeneous ad-hoc wireless networks with UAVs

    NASA Astrophysics Data System (ADS)

    Gu, Daniel L.; Gerla, Mario; Ly, Henry; Xu, Kaixin; Kong, Jiejun; Hong, Xiaoyan

    2001-10-01

    Multi-Layer Ad Hoc Wireless Networks with UAVs is an ideal infrastructure to establish a rapidly deployable wireless communication system any time any where in the world for military applications. In this paper, we review the research we have done so far for our heterogeneous solution. First of all, we proposed the infrastructure of Multi-level Heterogeneous Ad-Hoc Wireless Network with UAVs. Second, we developed a new MAC layer protocol, Centralized Intelligent Channel Assigned Multiple Access (C-ICAMA), for ground mobile backbone nodes to access UAV. Third, we extended HSR (Hierarchical State Routing) to this Multi-Level Heterogeneous Ad-Hoc Wireless Network. Due to the intrinsic limitations of Extended HSR, we extended the Landmark Ad Hoc Routing (LANMAR) as our forth step. Security is a critical issue for mobile ad-hoc wireless networks, especially for military applications. We developed an embedded distributed security protocol and integrated with this heterogeneous hierarchical ad hoc wireless networks in our fifth step. Therefore, the hierarchical multi-layer approach is the most desirable approach to achieve routing scalability in multi-hop wireless networks.

  18. Predicting impact of multi-paths on phase change in map-based vehicular ad hoc networks

    NASA Astrophysics Data System (ADS)

    Rahmes, Mark; Lemieux, George; Sonnenberg, Jerome; Chester, David B.

    2014-05-01

    Dynamic Spectrum Access, which through its ability to adapt the operating frequency of a radio, is widely believed to be a solution to the limited spectrum problem. Mobile Ad Hoc Networks (MANETs) can extend high capacity mobile communications over large areas where fixed and tethered-mobile systems are not available. In one use case with high potential impact cognitive radio employs spectrum sensing to facilitate identification of allocated frequencies not currently accessed by their primary users. Primary users own the rights to radiate at a specific frequency and geographic location, secondary users opportunistically attempt to radiate at a specific frequency when the primary user is not using it. We quantify optimal signal detection in map based cognitive radio networks with multiple rapidly varying phase changes and multiple orthogonal signals. Doppler shift occurs due to reflection, scattering, and rapid vehicle movement. Path propagation as well as vehicle movement produces either constructive or destructive interference with the incident wave. Our signal detection algorithms can assist the Doppler spread compensation algorithm by deciding how many phase changes in signals are present in a selected band of interest. Additionally we can populate a spatial radio environment map (REM) database with known information that can be leveraged in an ad hoc network to facilitate Dynamic Spectrum Access. We show how topography can help predict the impact of multi-paths on phase change, as well as about the prediction from dense traffic areas. Utilization of high resolution geospatial data layers in RF propagation analysis is directly applicable.

  19. Further Development of Synchronous Array Method for Ad Hoc Wireless Networks

    NASA Astrophysics Data System (ADS)

    Yu, Yuan; Huang, Yi; Zhao, Bin; Hua, Yingbo

    2008-12-01

    A further development of the synchronous array method (SAM) as a medium access control scheme for large-scale ad hoc wireless networks is presented. Under SAM, all transmissions of data packets between adjacent nodes are synchronized on a frame-by-frame basis, and the spacing between concurrent cochannel transmissions of data packets is properly controlled. An opportunistic SAM (O-SAM) is presented which allows concurrent cochannel transmissions to be locally adaptive to channel gain variations. A distributed SAM (D-SAM) is discussed that schedules all concurrent cochannel transmissions in a distributed fashion. For networks of low mobility, the control overhead required by SAM can be made much smaller than the payload. By analysis and simulation, the intranetwork throughput of O-SAM and D-SAM is evaluated. The effects of traffic load and multiple antennas on the intranetwork throughput are studied. The throughput of ALOHA is also analyzed and compared with that of O-SAM and D-SAM. By a distance-weighted throughput, a comparison of long distance transmission versus short distance transmission is also presented. The study of D-SAM reveals an important insight into the MSH-DSCH protocol adopted in IEEE 802.16 standards.

  20. Ad Hoc modeling, expert problem solving, and R&T program evaluation

    NASA Technical Reports Server (NTRS)

    Silverman, B. G.; Liebowitz, J.; Moustakis, V. S.

    1983-01-01

    A simplified cost and time (SCAT) analysis program utilizing personal-computer technology is presented and demonstrated in the case of the NASA-Goddard end-to-end data system. The difficulties encountered in implementing complex program-selection and evaluation models in the research and technology field are outlined. The prototype SCAT system described here is designed to allow user-friendly ad hoc modeling in real time and at low cost. A worksheet constructed on the computer screen displays the critical parameters and shows how each is affected when one is altered experimentally. In the NASA case, satellite data-output and control requirements, ground-facility data-handling capabilities, and project priorities are intricately interrelated. Scenario studies of the effects of spacecraft phaseout or new spacecraft on throughput and delay parameters are shown. The use of a network of personal computers for higher-level coordination of decision-making processes is suggested, as a complement or alternative to complex large-scale modeling.

  1. Sketching Awareness: A Participatory Study to Elicit Designs for Supporting Ad Hoc Emergency Medical Teamwork

    PubMed Central

    Kusunoki, Diana; Sarcevic, Aleksandra; Zhang, Zhan; Yala, Maria

    2014-01-01

    Prior CSCW research on awareness in clinical settings has mostly focused on higher-level team coordination spanning across longer-term trajectories at the department and inter-department levels. In this paper, we offer a perspective on what awareness means within the context of an ad hoc, time- and safety-critical medical setting by looking at teams treating severely ill patients with urgent needs. We report findings from four participatory design workshops conducted with emergency medicine clinicians at two regional emergency departments. Workshops were developed to elicit design ideas for information displays that support awareness in emergency medical situations. Through analysis of discussions and clinicians’ sketches of information displays, we identified five features of teamwork that can be used as a foundation for supporting awareness from the perspective of clinicians. Based on these findings, we contribute rich descriptions of four facets of awareness that teams manage during emergency medical situations: team member awareness, elapsed time awareness, teamwork-oriented and patient-driven task awareness, and overall progress awareness. We then discuss these four awareness types in relation to awareness facets found in the CSCW literature. PMID:25870498

  2. An EEG–MEG Dissociation between Online Syntactic Comprehension and Post Hoc Reanalysis

    PubMed Central

    Meltzer, Jed A.; Braun, Allen R.

    2011-01-01

    Successful comprehension of syntactically complex sentences depends on online language comprehension mechanisms as well as reanalysis in working memory. To differentiate the neural substrates of these processes, we recorded electroencephalography and magnetoencephalography (MEG) during sentence-picture-matching in healthy subjects, assessing the effects of two difficulty factors: syntactic complexity (object-embedded vs. subject-embedded relative clauses) and semantic reversibility on neuronal oscillations during sentence presentation, and during a subsequent memory delay prior to picture onset. Synthetic Aperture magnetometry analysis of MEG showed that semantic reversibility induced left lateralized perisylvian power decreases in a broad frequency range, approximately 8–30 Hz. This effect followed the relative clause presentation and persisted throughout the remainder of the sentence and the subsequent memory delay period, shifting to a more frontal distribution during the delay. In contrast, syntactic complexity induced enhanced power decreases only during the delay period, in bilateral frontal and anterior temporal regions. These results indicate that detailed syntactic parsing of auditory language input may be augmented in the absence of alternative cues for thematic role assignment, as reflected by selective perisylvian engagement for reversible sentences, compared with irreversible sentences in which world knowledge constrains possible thematic roles. Furthermore, comprehension of complex syntax appears to depend on post hoc reanalysis in working memory implemented by frontal regions in both hemispheres. PMID:21331355

  3. Dynamic Agent Classification and Tracking Using an Ad Hoc Mobile Acoustic Sensor Network

    NASA Astrophysics Data System (ADS)

    Friedlander, David; Griffin, Christopher; Jacobson, Noah; Phoha, Shashi; Brooks, Richard R.

    2003-12-01

    Autonomous networks of sensor platforms can be designed to interact in dynamic and noisy environments to determine the occurrence of specified transient events that define the dynamic process of interest. For example, a sensor network may be used for battlefield surveillance with the purpose of detecting, identifying, and tracking enemy activity. When the number of nodes is large, human oversight and control of low-level operations is not feasible. Coordination and self-organization of multiple autonomous nodes is necessary to maintain connectivity and sensor coverage and to combine information for better understanding the dynamics of the environment. Resource conservation requires adaptive clustering in the vicinity of the event. This paper presents methods for dynamic distributed signal processing using an ad hoc mobile network of microsensors to detect, identify, and track targets in noisy environments. They seamlessly integrate data from fixed and mobile platforms and dynamically organize platforms into clusters to process local data along the trajectory of the targets. Local analysis of sensor data is used to determine a set of target attribute values and classify the target. Sensor data from a field test in the Marine base at Twentynine Palms, Calif, was analyzed using the techniques described in this paper. The results were compared to "ground truth" data obtained from GPS receivers on the vehicles.

  4. Emergency Situation Prediction Mechanism: A Novel Approach for Intelligent Transportation System Using Vehicular Ad Hoc Networks

    PubMed Central

    Gokulakrishnan, P.

    2015-01-01

    In Indian four-lane express highway, millions of vehicles are travelling every day. Accidents are unfortunate and frequently occurring in these highways causing deaths, increase in death toll, and damage to infrastructure. A mechanism is required to avoid such road accidents at the maximum to reduce the death toll. An Emergency Situation Prediction Mechanism, a novel and proactive approach, is proposed in this paper for achieving the best of Intelligent Transportation System using Vehicular Ad Hoc Network. ESPM intends to predict the possibility of occurrence of an accident in an Indian four-lane express highway. In ESPM, the emergency situation prediction is done by the Road Side Unit based on (i) the Status Report sent by the vehicles in the range of RSU and (ii) the road traffic flow analysis done by the RSU. Once the emergency situation or accident is predicted in advance, an Emergency Warning Message is constructed and disseminated to all vehicles in the area of RSU to alert and prevent the vehicles from accidents. ESPM performs well in emergency situation prediction in advance to the occurrence of an accident. ESPM predicts the emergency situation within 0.20 seconds which is comparatively less than the statistical value. The prediction accuracy of ESPM against vehicle density is found better in different traffic scenarios. PMID:26065014

  5. An adaptive neural swarm approach for intrusion defense in ad hoc networks

    NASA Astrophysics Data System (ADS)

    Cannady, James

    2011-06-01

    Wireless sensor networks (WSN) and mobile ad hoc networks (MANET) are being increasingly deployed in critical applications due to the flexibility and extensibility of the technology. While these networks possess numerous advantages over traditional wireless systems in dynamic environments they are still vulnerable to many of the same types of host-based and distributed attacks common to those systems. Unfortunately, the limited power and bandwidth available in WSNs and MANETs, combined with the dynamic connectivity that is a defining characteristic of the technology, makes it extremely difficult to utilize traditional intrusion detection techniques. This paper describes an approach to accurately and efficiently detect potentially damaging activity in WSNs and MANETs. It enables the network as a whole to recognize attacks, anomalies, and potential vulnerabilities in a distributive manner that reflects the autonomic processes of biological systems. Each component of the network recognizes activity in its local environment and then contributes to the overall situational awareness of the entire system. The approach utilizes agent-based swarm intelligence to adaptively identify potential data sources on each node and on adjacent nodes throughout the network. The swarm agents then self-organize into modular neural networks that utilize a reinforcement learning algorithm to identify relevant behavior patterns in the data without supervision. Once the modular neural networks have established interconnectivity both locally and with neighboring nodes the analysis of events within the network can be conducted collectively in real-time. The approach has been shown to be extremely effective in identifying distributed network attacks.

  6. A Game Theory Algorithm for Intra-Cluster Data Aggregation in a Vehicular Ad Hoc Network

    PubMed Central

    Chen, Yuzhong; Weng, Shining; Guo, Wenzhong; Xiong, Naixue

    2016-01-01

    Vehicular ad hoc networks (VANETs) have an important role in urban management and planning. The effective integration of vehicle information in VANETs is critical to traffic analysis, large-scale vehicle route planning and intelligent transportation scheduling. However, given the limitations in the precision of the output information of a single sensor and the difficulty of information sharing among various sensors in a highly dynamic VANET, effectively performing data aggregation in VANETs remains a challenge. Moreover, current studies have mainly focused on data aggregation in large-scale environments but have rarely discussed the issue of intra-cluster data aggregation in VANETs. In this study, we propose a multi-player game theory algorithm for intra-cluster data aggregation in VANETs by analyzing the competitive and cooperative relationships among sensor nodes. Several sensor-centric metrics are proposed to measure the data redundancy and stability of a cluster. We then study the utility function to achieve efficient intra-cluster data aggregation by considering both data redundancy and cluster stability. In particular, we prove the existence of a unique Nash equilibrium in the game model, and conduct extensive experiments to validate the proposed algorithm. Results demonstrate that the proposed algorithm has advantages over typical data aggregation algorithms in both accuracy and efficiency. PMID:26907272

  7. An EEG-MEG Dissociation between Online Syntactic Comprehension and Post Hoc Reanalysis.

    PubMed

    Meltzer, Jed A; Braun, Allen R

    2011-01-01

    Successful comprehension of syntactically complex sentences depends on online language comprehension mechanisms as well as reanalysis in working memory. To differentiate the neural substrates of these processes, we recorded electroencephalography and magnetoencephalography (MEG) during sentence-picture-matching in healthy subjects, assessing the effects of two difficulty factors: syntactic complexity (object-embedded vs. subject-embedded relative clauses) and semantic reversibility on neuronal oscillations during sentence presentation, and during a subsequent memory delay prior to picture onset. Synthetic Aperture magnetometry analysis of MEG showed that semantic reversibility induced left lateralized perisylvian power decreases in a broad frequency range, approximately 8-30 Hz. This effect followed the relative clause presentation and persisted throughout the remainder of the sentence and the subsequent memory delay period, shifting to a more frontal distribution during the delay. In contrast, syntactic complexity induced enhanced power decreases only during the delay period, in bilateral frontal and anterior temporal regions. These results indicate that detailed syntactic parsing of auditory language input may be augmented in the absence of alternative cues for thematic role assignment, as reflected by selective perisylvian engagement for reversible sentences, compared with irreversible sentences in which world knowledge constrains possible thematic roles. Furthermore, comprehension of complex syntax appears to depend on post hoc reanalysis in working memory implemented by frontal regions in both hemispheres. PMID:21331355

  8. A Game Theory Algorithm for Intra-Cluster Data Aggregation in a Vehicular Ad Hoc Network.

    PubMed

    Chen, Yuzhong; Weng, Shining; Guo, Wenzhong; Xiong, Naixue

    2016-01-01

    Vehicular ad hoc networks (VANETs) have an important role in urban management and planning. The effective integration of vehicle information in VANETs is critical to traffic analysis, large-scale vehicle route planning and intelligent transportation scheduling. However, given the limitations in the precision of the output information of a single sensor and the difficulty of information sharing among various sensors in a highly dynamic VANET, effectively performing data aggregation in VANETs remains a challenge. Moreover, current studies have mainly focused on data aggregation in large-scale environments but have rarely discussed the issue of intra-cluster data aggregation in VANETs. In this study, we propose a multi-player game theory algorithm for intra-cluster data aggregation in VANETs by analyzing the competitive and cooperative relationships among sensor nodes. Several sensor-centric metrics are proposed to measure the data redundancy and stability of a cluster. We then study the utility function to achieve efficient intra-cluster data aggregation by considering both data redundancy and cluster stability. In particular, we prove the existence of a unique Nash equilibrium in the game model, and conduct extensive experiments to validate the proposed algorithm. Results demonstrate that the proposed algorithm has advantages over typical data aggregation algorithms in both accuracy and efficiency. PMID:26907272

  9. The effects of malicious nodes on performance of mobile ad hoc networks

    NASA Astrophysics Data System (ADS)

    Li, Fanzhi; Shi, Xiyu; Jassim, Sabah; Adams, Christopher

    2006-05-01

    Wireless ad hoc networking offers convenient infrastructureless communication over the shared wireless channel. However, the nature of ad hoc networks makes them vulnerable to security attacks. Unlike their wired counterpart, infrastructureless ad hoc networks do not have a clear line of defense, their topology is dynamically changing, and every mobile node can receive messages from its neighbors and can be contacted by all other nodes in its neighborhood. This poses a great danger to network security if some nodes behave in a malicious manner. The immediate concern about the security in this type of networks is how to protect the network and the individual mobile nodes against malicious act of rogue nodes from within the network. This paper is concerned with security aspects of wireless ad hoc networks. We shall present results of simulation experiments on ad hoc network's performance in the presence of malicious nodes. We shall investigate two types of attacks and the consequences will be simulated and quantified in terms of loss of packets and other factors. The results show that network performance, in terms of successful packet delivery ratios, significantly deteriorates when malicious nodes act according to the defined misbehaving characteristics.

  10. Structure and spectroscopic properties of low-lying states of the HOC(O)O radical.

    PubMed

    Linguerri, Roberto; Puzzarini, Cristina; Francisco, Joseph S

    2016-02-28

    The HOC(O)O radical is a product of the reaction of HOCO radicals with oxygen atoms. The present study provides theoretical prediction of critical spectroscopic features of this radical that should aid in its experimental characterization. Energies, structures, rotational constants, and harmonic frequencies are presented for the ground and two low-lying excited electronic states of HOC(O)O. The energies for the Ã(2)A(″)←X̃(2)A(') and B̃(2)A(')←X̃(2)A(') electronic transitions are reported. The band origin of the B̃←X̃ transition of HOC(O)O is predicted to occur in the near infrared region of the spectrum at around 1.5 eV and it is suggested to be the most promising one for observing this radical spectroscopically. The structural and spectroscopic similarities between HOC(O)O and the isoelectronic radical FC(O)O are discussed. The abundance of experimental data on the FC(O)O radical should guide the spectroscopic characterization of HOC(O)O and serve as a benchmark for the structural and spectroscopic parameters obtained from theory. PMID:26931701

  11. Time geography for ad-hoc shared-ride trip planning in mobile geosensor networks

    NASA Astrophysics Data System (ADS)

    Raubal, Martin; Winter, Stephan; Teβmann, Sven; Gaisbauer, Christian

    Ad-hoc shared-ride trip planning in an urban environment is a complex task within a non-deterministic transportation network. Mobile geosensor networks provide the technical environment for realizing ad-hoc shared-ride trip planning: Network nodes are autonomous agents that interact locally by ad-hoc short-range communication and arrange for shared rides. In a mobile geosensor network, communication costs are critical because of constraints regarding bandwidth, available energy, and memory. This paper introduces spatio-temporal concepts from time geography, which can be employed during the planning process to significantly reduce communication costs. We will integrate network-based algorithms and different wayfinding strategies to assist both shared-ride clients and hosts in finding optimal travel assignments. Multi-agent geosimulation in a real street network is used to demonstrate the applicability of the approach and quantitatively confirm the theoretically foreseen reduction in communication costs.

  12. Energetics of the protonation of CO - Implications for the observation of HOC(+) in dense interstellar clouds

    NASA Technical Reports Server (NTRS)

    Dixon, D.; Komornicki, A.; Kraemer, W. P.

    1984-01-01

    A number of molecular species on the H3CO(+) energy hypersurface is examined. Ab initio molecular orbital theory is used to determine the structures and relative energetics of the two isomers of HCO(+) and HOC(+) together with the affinity of CO for protonation at either end. The proton affinities of H2 and H2CO are also examined. The calculations are performed using large basis sets and include the effects of electron correlation. The calculated vibrational frequencies are used to correct for zero point energy differences. The results show that the proton affinities of H2 and CO to form HOC(+) are within 1 kcal of each other. The calculations demonstrate that there is no thermodynamic driving force to form HOC(+) in collisions of H3(+) with CO, and that the formation of HCO(+) in such collisions is very exoergic. A plausible mechanism is suggested to explain the differences observed between the laboratory and the interstellar medium.

  13. Fuzzy Multiple Metrics Link Assessment for Routing in Mobile Ad-Hoc Network

    NASA Astrophysics Data System (ADS)

    Soo, Ai Luang; Tan, Chong Eng; Tay, Kai Meng

    2011-06-01

    In this work, we investigate on the use of Sugeno fuzzy inference system (FIS) in route selection for mobile Ad-Hoc networks (MANETs). Sugeno FIS is introduced into Ad-Hoc On Demand Multipath Distance Vector (AOMDV) routing protocol, which is derived from its predecessor, Ad-Hoc On Demand Distance Vector (AODV). Instead of using the conventional way that considering only a single metric to choose the best route, our proposed fuzzy decision making model considers up to three metrics. In the model, the crisp inputs of the three parameters are fed into an FIS and being processed in stages, i.e., fuzzification, inference, and defuzzification. Finally, after experiencing all the stages, a single value score is generated from the combination metrics, which will be used to measure all the discovered routes credibility. Results obtained from simulations show a promising improvement as compared to AOMDV and AODV.

  14. A Decentralized VPN Service over Generalized Mobile Ad-Hoc Networks

    NASA Astrophysics Data System (ADS)

    Fujita, Sho; Shima, Keiichi; Uo, Yojiro; Esaki, Hiroshi

    We present a decentralized VPN service that can be built over generalized mobile ad-hoc networks (Generalized MANETs), in which topologies can be represented as a time-varying directed multigraph. We address wireless ad-hoc networks and overlay ad-hoc networks as instances of Generalized MANETs. We first propose an architecture to operate on various kinds of networks through a single set of operations. Then, we design and implement a decentralized VPN service on the proposed architecture. Through the development and operation of a prototype system we implemented, we found that the proposed architecture makes the VPN service applicable to each instance of Generalized MANETs, and that the VPN service makes it possible for unmodified applications to operate on the networks.

  15. Intelligent Sensing and Classification in DSR-Based Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Dempsey, Tae; Sahin, Gokhan; Morton, Yu T. (Jade

    Wireless ad hoc networks have fundamentally altered today's battlefield, with applications ranging from unmanned air vehicles to randomly deployed sensor networks. Security and vulnerabilities in wireless ad hoc networks have been considered at different layers, and many attack strategies have been proposed, including denial of service (DoS) through the intelligent jamming of the most critical packet types of flows in a network. This paper investigates the effectiveness of intelligent jamming in wireless ad hoc networks using the Dynamic Source Routing (DSR) and TCP protocols and introduces an intelligent classifier to facilitate the jamming of such networks. Assuming encrypted packet headers and contents, our classifier is based solely on the observable characteristics of size, inter-arrival timing, and direction and classifies packets with up to 99.4% accuracy in our experiments.

  16. Routing in wireless ad hoc and sensor network underground with sensor data in real-time

    NASA Astrophysics Data System (ADS)

    Odei-Lartey, Emmanuel; Hartmann, Klaus; Ahmadian, Hamidreza

    2012-05-01

    This paper first describes the innovative topology and structure of a wireless ad hoc and sensor network in a so called line-in-the-underground formation and the feasibility of achieving a reliable wireless connection underground with regards to a borehole telemetry system. It further describes a routing algorithm/protocol implementation based on a modification of the ad hoc on-demand distance vector protocol to achieve a reliable underground communication scheme for the wireless ad hoc network deployed underground for sensor data acquisition in real time as applied in the borehole telemetry system. Simulations and experiments are conducted to investigate and verify the effectiveness of this routing technique and the performance results are shown.

  17. Impact of network structure on the capacity of wireless multihop ad hoc communication

    NASA Astrophysics Data System (ADS)

    Krause, Wolfram; Glauche, Ingmar; Sollacher, Rudolf; Greiner, Martin

    2004-07-01

    As a representative of a complex technological system, the so-called wireless multihop ad hoc communication networks are discussed. They represent an infrastructure-less generalization of todays wireless cellular phone networks. Lacking a central control authority, the ad hoc nodes have to coordinate themselves such that the overall network performs in an optimal way. A performance indicator is the end-to-end throughput capacity. Various models, generating differing ad hoc network structure via differing transmission power assignments, are constructed and characterized. They serve as input for a generic data traffic simulation as well as some semi-analytic estimations. The latter reveal that due to the most-critical-node effect the end-to-end throughput capacity sensitively depends on the underlying network structure, resulting in differing scaling laws with respect to network size.

  18. Deny-by-Default Distributed Security Policy Enforcement in Mobile Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Alicherry, Mansoor; Keromytis, Angelos D.; Stavrou, Angelos

    Mobile Ad-hoc Networks (MANETs) are increasingly employed in tactical military and civil rapid-deployment networks, including emergency rescue operations and ad hoc disaster-relief networks. However, this flexibility of MANETs comes at a price, when compared to wired and base station-based wireless networks: MANETs are susceptible to both insider and outsider attacks. This is mainly because of the lack of a well-defined defense perimeter preventing the effective use of wired defenses including firewalls and intrusion detection systems.

  19. An ab initio molecular dynamics study of the roaming mechanism of the H2+HOC+ reaction

    NASA Astrophysics Data System (ADS)

    Yu, Hua-Gen

    2011-08-01

    We report here a direct ab initio molecular dynamics study of the p-/o-H2+HOC+ reaction on the basis of the accurate SAC-MP2 potential energy surface. The quasi-classical trajectory method was employed. This work largely focuses on the study of reaction mechanisms. A roaming mechanism was identified for this molecular ion-molecule reaction. The driving forces behind the roaming mechanism were thoroughly investigated by using a trajectory dynamics approach. In addition, the thermal rate coefficients of the H2+HOC+ reaction were calculated in the temperature range [25, 300] K and are in good agreement with experiments.

  20. Reliable on-demand multicast routing with congestion control in wireless ad hoc networks

    NASA Astrophysics Data System (ADS)

    Tang, Ken; Gerla, Mario

    2001-07-01

    In this paper, we address the congestion control multicast routing problem in wireless ad hoc networks through the medium access control (MAC) layer. We first introduce the Broadcast Medium Window (BMW) MAC protocol, which provides reliable delivery to broadcast packets at the MAC layer. We then extend the wireless On-Demand Multicast Routing Protocol (ODMRP) to facilitate congestion control in ad hoc networks using BMW. Through simulation, we show that ODMRP with congestion control adapts well to multicast sources that are aggressive in data transmissions.

  1. Energy Efficient and QoS sensitive Routing Protocol for Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Saeed Tanoli, Tariq; Khalid Khan, Muhammad

    2013-12-01

    Efficient routing is an important part of wireless ad hoc networks. Since in ad hoc networks we have limited resources, there are many limitations like bandwidth, battery consumption, and processing cycle etc. Reliability is also necessary since there is no allowance for invalid or incomplete information (and expired data is useless). There are various protocols that perform routing by considering one parameter but ignoring other parameters. In this paper we present a protocol that finds route on the basis of bandwidth, energy and mobility of the nodes participating in the communication.

  2. IDMA: improving the defense against malicious attack for mobile ad hoc networks based on ARIP protocol

    NASA Astrophysics Data System (ADS)

    Peng, Chaorong; Chen, Chang Wen

    2008-04-01

    Malicious nodes are mounting increasingly sophisticated attacking operations on the Mobile Ad Hoc Networks (MANETs). This is mainly because the IP-based MANETs are vulnerable to attacks by various malicious nodes. However, the defense against malicious attack can be improved when a new layer of network architecture can be developed to separate true IP address from disclosing to the malicious nodes. In this paper, we propose a new algorithm to improve the defense against malicious attack (IDMA) that is based on a recently developed Assignment Router Identify Protocol (ARIP) for the clustering-based MANET management. In the ARIP protocol, we design the ARIP architecture based on the new Identity instead of the vulnerable IP addresses to provide the required security that is embedded seamlessly into the overall network architecture. We make full use of ARIP's special property to monitor gateway forward packets by Reply Request Route Packets (RREP) without additional intrusion detection layer. We name this new algorithm IDMA because of its inherent capability to improve the defense against malicious attacks. Through IDMA, a watching algorithm can be established so as to counterattack the malicious node in the routing path when it unusually drops up packets. We provide analysis examples for IDMA for the defense against a malicious node that disrupts the route discovery by impersonating the destination, or by responding with state of corrupted routing information, or by disseminating forged control traffic. The IDMA algorithm is able to counterattack the malicious node in the cases when the node lunch DoS attack by broadcast a large number of route requests, or make Target traffic congestion by delivering huge mount of data; or spoof the IP addresses and send forge packets with a fake ID to the same Target causing traffic congestion at that destination. We have implemented IDMA algorism using the GloMoSim simulator and have demonstrated its performance under a variety of

  3. Protocols for Detection and Removal of Wormholes for Secure Routing and Neighborhood Creation in Wireless Ad Hoc Networks

    ERIC Educational Resources Information Center

    Hayajneh, Thaier Saleh

    2009-01-01

    Wireless ad hoc networks are suitable and sometimes the only solution for several applications. Many applications, particularly those in military and critical civilian domains (such as battlefield surveillance and emergency rescue) require that ad hoc networks be secure and stable. In fact, security is one of the main barriers to the extensive use…

  4. The 5th Meeting of the Ad Hoc Panel on Terminal Configured Vehicles

    NASA Technical Reports Server (NTRS)

    1977-01-01

    A report of the fifth meeting of the NASA Research and Technology Advisory Council, Ad Hoc panel on Terminal Configured Vehicles is presented. Some of the following topics were discussed; (1) microwave landing systems; (2) whole word computer system status; (3) flight path angle control: (4) VTOL approaches and landing technology; and (5) simulation study in wind shear.

  5. Report of the Ad Hoc Committee on Religious and Cultural Celebrations in the Library.

    ERIC Educational Resources Information Center

    Rathemacher, Andree; Grubman, Sheila Black; Lahiri, Amar; Gilton, Donna; Sharif, Mohammed

    The charge of the University of Rhode Island's Ad Hoc Committee on Religious and Cultural Celebrations in the Library was to: investigate all opportunities for the library to educate the campus community about religious and cultural holidays; consider all the major religions of the world and the possibility of having displays for the symbols of…

  6. Report of the Council for Exceptional Children's Ad Hoc Committee on Medically Fragile Students.

    ERIC Educational Resources Information Center

    Council for Exceptional Children, Reston, VA.

    New opportunities are available for students with special health care needs requiring specialized technological health care procedures for life support and/or health support, and attention to appropriate educational programs is required. Guidelines proposed by the Council for Exceptional Children's Ad Hoc Committee on Medically Fragile Students…

  7. An Alternative Multivariate One- and Two-Sample Post Hoc Procedure.

    ERIC Educational Resources Information Center

    Mihevic, Patricia M.; Spray, Judith A.

    1979-01-01

    A multivariate post hoc procedure (the Roy-Bose procedure) which allows for the construction of an infinite number of confidence intervals or probability statements concerning the p variables, all of which hold at a 100(1-a) percent level of confidence, is demonstrated and compared to other procedures. (JD)

  8. Data Security in Ad Hoc Networks Using Randomization of Cryptographic Algorithms

    NASA Astrophysics Data System (ADS)

    Krishna, B. Ananda; Radha, S.; Keshava Reddy, K. Chenna

    Ad hoc networks are a new wireless networking paradigm for mobile hosts. Unlike traditional mobile wireless networks, ad hoc networks do not rely on any fixed infrastructure. Instead, hosts rely on each other to keep the network connected. The military tactical and other security-sensitive operations are still the main applications of ad hoc networks, although there is a trend to adopt ad hoc networks for commercial uses due to their unique properties. One main challenge in design of these networks is how to feasibly detect and defend the major attacks against data, impersonation and unauthorized data modification. Also, in the same network some nodes may be malicious whose objective is to degrade the network performance. In this study, we propose a security model in which the packets are encrypted and decrypted using multiple algorithms where the selection scheme is random. The performance of the proposed model is analyzed and it is observed that there is no increase in control overhead but a slight delay is introduced due to the encryption process. We conclude that the proposed security model works well for heavily loaded networks with high mobility and can be extended for more cryptographic algorithms.

  9. Student Self-Assessment in HOCS Science Examinations: Is There a Problem?

    NASA Astrophysics Data System (ADS)

    Zoller, Uri; Ben-Chaim, David

    1998-06-01

    A specially-designed self-assessment questionnaire (SAQHOCS), containing higher-order cognitive skills (HOCS)-type questions, was administered to 71 biology majors, enrolled in a four-year college program. The gap between students' self-assessment marking, and that of their HOCS-biased teachers (the authors), is accounted for by the prevailing LOCS-orientation and the "testing culture"—a total separation between testing and learning—in contemporary science teaching. The majority of the students in the study evaluated themselves as capable of self-assessment, and felt reasonably confident in doing so. They were quite reserved as far as the applicability of the self-assessment method to nonalgorithmic ("correct/incorrect") questions is concerned. The results of this study suggest that the potential for student self-assessment within college science teaching and learning exists. However, still a great purposed effort in HOCS-oriented teaching and learning is required in order for the student self-assessment practice to become a routine integral component of HOCS science examinations.

  10. Work, Family, and Community: Summary Proceedings of an Ad Hoc Committee.

    ERIC Educational Resources Information Center

    Hayes, Cheryl D., Ed.

    These proceedings contain summaries of five working group discussions and a discussion of suggestions for future research from an ad hoc meeting on Work, Family, and Community (Fedruary 21-22, 1980) in Washington, D.C. The meeting had these objectives: (1) to identify salient policy and research issues associated with changing patterns of labor…

  11. 75 FR 43565 - NASA Advisory Council; Ad-Hoc Task Force on Planetary Defense; Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-07-26

    ... SPACE ADMINISTRATION NASA Advisory Council; Ad-Hoc Task Force on Planetary Defense; Meeting AGENCY: National Aeronautics and Space Administration. ACTION: Notice of meeting. SUMMARY: In accordance with the Federal Advisory Committee Act, Public Law 92-463, as amended, the National Aeronautics and...

  12. 75 FR 15742 - NASA Advisory Council; Ad-Hoc Task Force on Planetary Defense; Meeting

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-03-30

    ... SPACE ADMINISTRATION NASA Advisory Council; Ad-Hoc Task Force on Planetary Defense; Meeting AGENCY: National Aeronautics and Space Administration. ACTION: Notice of meeting. SUMMARY: In accordance with the Federal Advisory Committee Act, Public Law 92-463, as amended, the National Aeronautics and...

  13. Final Report of the IAG AD Hoc Working Group on Global Change

    NASA Technical Reports Server (NTRS)

    Dickey, Jean O.

    1995-01-01

    None given. Paper gives final report of the IAG ad hoc working group on global change. They made three main recommendations to the group: 1. the post of and IAG liaison or representative to the IGBP should be established. 2. A new core program,.

  14. Scope of practice in audiology. Ad Hoc Committee on scope of Practice in Audiology.

    PubMed

    1996-01-01

    This scope of practice in audiology statement is an official policy of the American Speech-Language Hearing Association (ASHA). The document was developed by the ASHA Ad Hoc Committee on the Scope of Practice in Audiology and approved in 1995 by the Legislative Council (8-95). Members of the ad hoc committee include David Wark (chair), Tamara Adkins, J. Michael Dennis, Dana L. Oviatt, Lori Williams, and Evelyn Cherow (ex officio). Lawrence Higdon, ASHA vice president for professional practices in audiology, served as monitoring vice president. This statement supersedes the Scope of Practice, Speech-Language Pathology and Audiology statement (LC 6-89), Asha, April 1990, 1-2. PMID:8680260

  15. PNNI routing support for ad hoc mobile networking: The multilevel case

    SciTech Connect

    Martinez, L.; Sholander, P.; Tolendino, L.

    1998-01-01

    This contribution extends the Outside Nodal Hierarchy List (ONHL) procedures described in ATM Forum Contributions 97-0766 and 97-0933. These extensions allow multiple mobile networks to form either an ad hoc network or an extension of a fixed PNNI infrastructure. A previous contribution (97-1073) covered the simplest case where the top-most Logical Group Nodes (LGNs), in those mobile networks, all resided at the same level in a PNNI hierarchy. This contribution covers the more general case wherein those top-most LGNs may reside at different PNNI hierarchy levels. Both of the SNL contributions consider flat ad hoc network architectures in the sense that each mobile network always participates in the PNNI hierarchy at the pre-configured level of its top-most LGN.

  16. The Ad Hoc process to strengthen the framework convention on climate change

    SciTech Connect

    Ramakrishna, K.; Deutz, A.M.; Jacobsen, L.A.

    1995-11-01

    The Woods Hole Research Center convened an International Conference on The Ad Hoc Process to Strengthen the Framework Convention on Climate Change in Woods Hole, MA, on October 7-9, 1995. The conference was conducted to examine the prospects for successful adoption of a protocol to the Framework Convention on Climate Change by 1997. In preparation for the Second session of the Ad Hoc Group on the Berlin Mandate, several governmental and nongovernmental representatives met in Woods Hole to discuss the process and possible outcome of the Berlin Mandate negotiations for a protocol or other legal instrument to strengthen the Convention. The conference was by invitation and all participants attended in their personal capacities.

  17. Forming an ad-hoc nearby storage, based on IKAROS and social networking services

    NASA Astrophysics Data System (ADS)

    Filippidis, Christos; Cotronis, Yiannis; Markou, Christos

    2014-06-01

    We present an ad-hoc "nearby" storage, based on IKAROS and social networking services, such as Facebook. By design, IKAROS is capable to increase or decrease the number of nodes of the I/O system instance on the fly, without bringing everything down or losing data. IKAROS is capable to decide the file partition distribution schema, by taking on account requests from the user or an application, as well as a domain or a Virtual Organization policy. In this way, it is possible to form multiple instances of smaller capacity higher bandwidth storage utilities capable to respond in an ad-hoc manner. This approach, focusing on flexibility, can scale both up and down and so can provide more cost effective infrastructures for both large scale and smaller size systems. A set of experiments is performed comparing IKAROS with PVFS2 by using multiple clients requests under HPC IOR benchmark and MPICH2.

  18. PNNI routing support for ad hoc mobile networking: A flat architecture

    SciTech Connect

    Martinez, L.; Sholander, P.; Tolendino, L.

    1997-12-01

    This contribution extends the Outside Nodal Hierarchy List (ONHL) procedures described in ATM Form Contribution 97-0766. These extensions allow multiple mobile networks to form either an ad hoc network or an extension of a fixed PNNI infrastructure. This contribution covers the simplest case where the top-most Logical Group Nodes (LGNs), in those mobile networks, all reside at the same level in a PNNI hierarchy. Future contributions will cover the general case where those top-most LGNs reside at different hierarchy levels. This contribution considers a flat ad hoc network architecture--in the sense that each mobile network always participates in the PNNI hierarchy at the preconfigured level of its top-most LGN.

  19. Accurate ab initio quartic force fields for the ions HCO(+) and HOC(+)

    NASA Astrophysics Data System (ADS)

    Martin, J. M. L.; Taylor, Peter R.; Lee, Timothy J.

    1993-07-01

    The quartic force fields of HCO(+) and HOC(+) have been computed using augmented coupled cluster methods and basis sets of spdf and spdfg quality. Calculations on HCN, CO, and N2 have been performed to assist in calibrating the computed results. Going from an spdf to an spdfg basis shortens triple bonds by about 0.004 A, and increases the corresponding harmonic frequency by 10-20/cm, leaving bond distances about 0.003 A too long and triple bond stretching frequencies about 5/cm too low. Accurate estimates for the bond distances, fundamental frequencies, and thermochemical quantities are given. HOC(+) lies 37.8 +/- 0.5 kcal/mol (0 K) above HCO(+); the classical barrier height for proton exchange is 76.7 +/- 1.0 kcal/mol.

  20. Valid randomization-based p-values for partially post hoc subgroup analyses

    PubMed Central

    Lee, Joseph J.; Rubin, Donald B.

    2015-01-01

    By ‘partially post-hoc’ subgroup analyses, we mean analyses that compare existing data from a randomized experiment—from which a subgroup specification is derived—to new, subgroup-only experimental data. We describe a motivating example in which partially post hoc subgroup analyses instigated statistical debate about a medical device’s efficacy. We clarify the source of such analyses’ invalidity and then propose a randomization-based approach for generating valid posterior predictive p-values for such partially post hoc subgroups. Lastly, we investigate the approach’s operating characteristics in a simple illustrative setting through a series of simulations, showing that it can have desirable properties under both null and alternative hypotheses. PMID:25959735

  1. Integrating Overlay Protocols for Providing Autonomic Services in Mobile Ad-Hoc Networks

    NASA Astrophysics Data System (ADS)

    Gouvas, Panagiotis; Zafeiropoulos, Anastasios; Liakopoulos, Athanassios; Mentzas, Gregoris; Mitrou, Nikolas

    Next generation network characteristics increase the complexity in the design and provision of advanced services, making inappropriate the selection of traditional approaches. Future networks are becoming larger in scale, more dynamic and more heterogeneous. In order to cope with these requirements, services are expected to adapt to environmental conditions and require minimum human intervention. In this paper a new model for providing autonomous and decentralized services is proposed, especially focusing on mobile ad hoc networks (MANETs). Using a newly proposed four-layered approach, service development may be realized independently from the underlying physical network. In a reference implementation, it is demonstrated that it is possible to set up an overlay network that hides any network changes from the service layer. Multiple mechanisms have been adapted in order to efficiently — in terms of message exchanges and convergence time — operate over an ad hoc environment. Finally, it is demonstrated that a specific service could operate over a dynamic network with multiple failures.

  2. Enhancements for distributed certificate authority approaches for mobile wireless ad hoc networks.

    SciTech Connect

    Van Leeuwen, Brian P.; Michalski, John T.; Anderson, William Erik

    2003-12-01

    Mobile wireless ad hoc networks that are resistant to adversarial manipulation are necessary for distributed systems used in military and security applications. Critical to the successful operation of these networks, which operate in the presence of adversarial stressors, are robust and efficient information assurance methods. In this report we describe necessary enhancements for a distributed certificate authority (CA) used in secure wireless network architectures. Necessary cryptographic algorithms used in distributed CAs are described and implementation enhancements of these algorithms in mobile wireless ad hoc networks are developed. The enhancements support a network's ability to detect compromised nodes and facilitate distributed CA services. We provide insights to the impacts the enhancements will have on network performance with timing diagrams and preliminary network simulation studies.

  3. Vehicular ad hoc network for a surveillance system using multifrequency band enhancement

    NASA Astrophysics Data System (ADS)

    Bunruangses, Montree; Sunat, Khamron; Mitatha, Somsak; Yupapin, Preecha P.

    2010-09-01

    We present a new design of a surveillance system via a vehicular ad hoc network (VANET) integrated by a 3-G or 4-G cellular wireless network. We propose dense wavelength division multiplexing wavelength enhancement for increasing the channel capacity and signal security. Increase in the number of channels can be obtained by increasing the wavelength density. Signal security is introduced by a specific wavelength filter controlled by the central operator. Optical communication wavelength enhancement is reviewed. The advantage of this proposed system is that it can easily be implemented and incorporated into the existing communication link in either a cellular or ad hoc wireless system, where signal security and hence privacy can be provided.

  4. Adhoc: an R package to calculate ad hoc distance thresholds for DNA barcoding identification

    PubMed Central

    Sonet, Gontran; Jordaens, Kurt; Nagy, Zoltán T.; Breman, Floris C.; De Meyer, Marc; Backeljau, Thierry; Virgilio, Massimiliano

    2013-01-01

    Abstract Identification by DNA barcoding is more likely to be erroneous when it is based on a large distance between the query (the barcode sequence of the specimen to identify) and its best match in a reference barcode library. The number of such false positive identifications can be decreased by setting a distance threshold above which identification has to be rejected. To this end, we proposed recently to use an ad hoc distance threshold producing identifications with an estimated relative error probability that can be fixed by the user (e.g. 5%). Here we introduce two R functions that automate the calculation of ad hoc distance thresholds for reference libraries of DNA barcodes. The scripts of both functions, a user manual and an example file are available on the JEMU website (http://jemu.myspecies.info/computer-programs) as well as on the comprehensive R archive network (CRAN, http://cran.r-project.org). PMID:24453565

  5. Design of free patterns of nanocrystals with ad hoc features via templated dewetting

    SciTech Connect

    Aouassa, M.; Berbezier, I.; Favre, L.; Ronda, A.; Bollani, M.; Sordan, R.; Delobbe, A.; Sudraud, P.

    2012-07-02

    Design of monodisperse ultra-small nanocrystals (NCs) into large scale patterns with ad hoc features is demonstrated. The process makes use of solid state dewetting of a thin film templated through alloy liquid metal ion source focused ion beam (LMIS-FIB) nanopatterning. The solid state dewetting initiated at the edges of the patterns controllably creates the ordering of NCs with ad hoc placement and periodicity. The NC size is tuned by varying the nominal thickness of the film while their position results from the association of film retraction from the edges of the lay out and Rayleigh-like instability. The use of ultra-high resolution LMIS-FIB enables to produce monocrystalline NCs with size, periodicity, and placement tunable as well. It provides routes for the free design of nanostructures for generic applications in nanoelectronics.

  6. An Ad-Hoc Adaptive Pilot Model for Pitch Axis Gross Acquisition Tasks

    NASA Technical Reports Server (NTRS)

    Hanson, Curtis E.

    2012-01-01

    An ad-hoc algorithm is presented for real-time adaptation of the well-known crossover pilot model and applied to pitch axis gross acquisition tasks in a generic fighter aircraft. Off-line tuning of the crossover model to human pilot data gathered in a fixed-based high fidelity simulation is first accomplished for a series of changes in aircraft dynamics to provide expected values for model parameters. It is shown that in most cases, for this application, the traditional crossover model can be reduced to a gain and a time delay. The ad-hoc adaptive pilot gain algorithm is shown to have desirable convergence properties for most types of changes in aircraft dynamics.

  7. Adhoc: an R package to calculate ad hoc distance thresholds for DNA barcoding identification.

    PubMed

    Sonet, Gontran; Jordaens, Kurt; Nagy, Zoltán T; Breman, Floris C; De Meyer, Marc; Backeljau, Thierry; Virgilio, Massimiliano

    2013-12-30

    Identification by DNA barcoding is more likely to be erroneous when it is based on a large distance between the query (the barcode sequence of the specimen to identify) and its best match in a reference barcode library. The number of such false positive identifications can be decreased by setting a distance threshold above which identification has to be rejected. To this end, we proposed recently to use an ad hoc distance threshold producing identifications with an estimated relative error probability that can be fixed by the user (e.g. 5%). Here we introduce two R functions that automate the calculation of ad hoc distance thresholds for reference libraries of DNA barcodes. The scripts of both functions, a user manual and an example file are available on the JEMU website (http://jemu.myspecies.info/computer-programs) as well as on the comprehensive R archive network (CRAN, http://cran.r-project.org). PMID:24453565

  8. RHINO: armoured plated networking with intelligent high speed wireless ad hoc capability

    NASA Astrophysics Data System (ADS)

    Markarian, Garik; Singh, Farid

    2008-04-01

    This paper describes the concept of an intelligent high speed wireless ad-hoc network, which is currently being developed. The technology aims at, not replacing any of the existing standards, but aims to complement them in urban, military and hazardous environments. Known as Rhino, the technology is a platform independent, IP based network which will provide adequate bandwidth for real time video, audio and data traffic. The technology and specifications described in this paper are based on initial development of the technology.

  9. EGPS: An Efficient Privacy Preserving Scheme for Vehicular ad hoc Networks

    NASA Astrophysics Data System (ADS)

    Zhao, Baokang; Su, Xiangyu; Su, Jinshu; Song, Ziming; Sun, Yipin; Tao, Jing; Tang, Yong; Chen, Shuhui; Zhao, Guohong; Chen, Yijiao

    2010-09-01

    In this paper, we propose EGPS, an efficient privacy preserving scheme for vehicular ad hoc networks. The EGPS scheme is based on a very efficient group signature and Identity Based Cryptography(IBC) techniques. Several security properties of EGPS, including the correctness and unforgeability have been proved. Furthermore, EGPS is also proved to be more efficient than GSIS, which is currently one of the best state-of-the-art VANET privacy preserving schemes.

  10. VoIP Implementation and Experiments on a Mobile Wireless AdHoc Network

    NASA Astrophysics Data System (ADS)

    Zhang, Hongqi; Yang, Oliver; Zhao, Jiying

    We have implemented a testbed to study the performance of VoIP in wireless ad hoc networks. The ASNC (Adaptive Source Network-rate Control) scheme is used to battle packet loss by feeding MOS (Mean Opinion Score) and loss information back to the sender. Our different VoIP experiments with measurements on delay, packet loss rate and MOS have validated the feasibility and efficiency of our scheme. It further verifies the simulator we used in the initial investigation.

  11. An artificial immune system approach with secondary response for misbehavior detection in mobile ad hoc networks.

    PubMed

    Sarafijanović, Slavisa; Le Boudec, Jean-Yves

    2005-09-01

    In mobile ad hoc networks, nodes act both as terminals and information relays, and they participate in a common routing protocol, such as dynamic source routing (DSR). The network is vulnerable to routing misbehavior, due to faulty or malicious nodes. Misbehavior detection systems aim at removing this vulnerability. In this paper, we investigate the use of an artificial immune system (AIS) to detect node misbehavior in a mobile ad hoc network using DSR. The system is inspired by the natural immune system (IS) of vertebrates. Our goal is to build a system that, like its natural counterpart, automatically learns, and detects new misbehavior. We describe our solution for the classification task of the AIS; it employs negative selection and clonal selection, the algorithms for learning and adaptation used by the natural IS. We define how we map the natural IS concepts such as self, antigen, and antibody to a mobile ad hoc network and give the resulting algorithm for classifying nodes as misbehaving. We implemented the system in the network simulator Glomosim; we present detection results and discuss how the system parameters affect the performance of primary and secondary response. Further steps will extend the design by using an analogy to the innate system, danger signal, and memory cells. PMID:16252818

  12. Cross-Layer Service Discovery Mechanism for OLSRv2 Mobile Ad Hoc Networks.

    PubMed

    Vara, M Isabel; Campo, Celeste

    2015-01-01

    Service discovery plays an important role in mobile ad hoc networks (MANETs). The lack of central infrastructure, limited resources and high mobility make service discovery a challenging issue for this kind of network. This article proposes a new service discovery mechanism for discovering and advertising services integrated into the Optimized Link State Routing Protocol Version 2 (OLSRv2). In previous studies, we demonstrated the validity of a similar service discovery mechanism integrated into the previous version of OLSR (OLSRv1). In order to advertise services, we have added a new type-length-value structure (TLV) to the OLSRv2 protocol, called service discovery message (SDM), according to the Generalized MANET Packet/Message Format defined in Request For Comments (RFC) 5444. Each node in the ad hoc network only advertises its own services. The advertisement frequency is a user-configurable parameter, so that it can be modified depending on the user requirements. Each node maintains two service tables, one to store information about its own services and another one to store information about the services it discovers in the network. We present simulation results, that compare our service discovery integrated into OLSRv2 with the one defined for OLSRv1 and with the integration of service discovery in Ad hoc On-demand Distance Vector (AODV) protocol, in terms of service discovery ratio, service latency and network overhead. PMID:26205272

  13. In search of reflective behavior and shared understanding in ad hoc expert teams.

    PubMed

    Mulder, Ingrid; Swaak, Janine; Kessels, Joseph

    2004-04-01

    The work reported on here concentrates on virtual ad hoc expert teams for the integration of learning and working, as ad hoc teams seem to be one way to cope with complexity in a knowledge-intensive society. In order to let ad hoc teams learn and work together, group members require effective communication and shared understanding among each other. Two empirical studies were conducted to study collaborative learning and shared understanding, one exploratory study and one experiment. In the first study, it was explored how virtual design teams work and learn together. Based on conceptual ideas, collaborative learning and shared understanding were observed and assessed in a design team over a period of four months. It was concluded that shared understanding was suboptimal; mainly due to the effect that hardly any questions were raised and answered. The second study elaborates on the need to encourage question-answer patterns and reflective behavior in such teams. A tool was developed that supported questioning behavior. As it was hypothesized that this tool leads to better questioning behavior, which in turn results in more reflective behavior and in increased shared understanding, an experiment was conducted. In the exploratory study, as well as in the experimental study, the perceived shared understanding increased over time. However, in both studies suboptimal questioning behavior and little reflective activity were noticed. The main results of the two empirical studies are compared and discussed. PMID:15140358

  14. Real Time Semantic Interoperability in AD HOC Networks of Geospatial Data Sources: Challenges, Achievements and Perspectives

    NASA Astrophysics Data System (ADS)

    Mostafavi, M. A.; Bakillah, M.

    2012-07-01

    Recent advances in geospatial technologies have made available large amount of geospatial data. Meanwhile, new developments in Internet and communication technologies created a shift from isolated geospatial databases to ad hoc networks of geospatial data sources, where data sources can join or leave the network, and form groups to share data and services. However, effective integration and sharing of geospatial data among these data sources and their users are hampered by semantic heterogeneities. These heterogeneities affect the spatial, temporal and thematic aspects of geospatial concepts. There have been many efforts to address semantic interoperability issues in the geospatial domain. These efforts were mainly focused on resolving heterogeneities caused by different and implicit representations of the concepts. However, many approaches have focused on the thematic aspects, leaving aside the explicit representation of spatial and temporal aspects. Also, most semantic interoperability approaches for networks have focused on automating the semantic mapping process. However, the ad hoc network structure is continuously modified by source addition or removal, formation of groups, etc. This dynamic aspect is often neglected in those approaches. This paper proposes a conceptual framework for real time semantic interoperability in ad hoc networks of geospatial data sources. The conceptual framework presents the fundamental elements of real time semantic interoperability through a hierarchy of interrelated semantic states and processes. Then, we use the conceptual framework to set the discussion on the achievements that have already been made, the challenges that remain to be addressed and perspectives with respect to these challenges.

  15. Cross-Layer Service Discovery Mechanism for OLSRv2 Mobile Ad Hoc Networks

    PubMed Central

    Vara, M. Isabel; Campo, Celeste

    2015-01-01

    Service discovery plays an important role in mobile ad hoc networks (MANETs). The lack of central infrastructure, limited resources and high mobility make service discovery a challenging issue for this kind of network. This article proposes a new service discovery mechanism for discovering and advertising services integrated into the Optimized Link State Routing Protocol Version 2 (OLSRv2). In previous studies, we demonstrated the validity of a similar service discovery mechanism integrated into the previous version of OLSR (OLSRv1). In order to advertise services, we have added a new type-length-value structure (TLV) to the OLSRv2 protocol, called service discovery message (SDM), according to the Generalized MANET Packet/Message Format defined in Request For Comments (RFC) 5444. Each node in the ad hoc network only advertises its own services. The advertisement frequency is a user-configurable parameter, so that it can be modified depending on the user requirements. Each node maintains two service tables, one to store information about its own services and another one to store information about the services it discovers in the network. We present simulation results, that compare our service discovery integrated into OLSRv2 with the one defined for OLSRv1 and with the integration of service discovery in Ad hoc On-demand Distance Vector (AODV) protocol, in terms of service discovery ratio, service latency and network overhead. PMID:26205272

  16. A Dirichlet reputation system in reliable routing of wireless ad hoc network

    SciTech Connect

    Yang, Dr. Li; Cui, Xiaohui; Cemerlic, Alma

    2010-01-01

    Ad hoc networks are very helpful in situations when no fixed network infrastructure is available, such as natural disasters and military conflicts. In such a network, all wireless nodes are equal peers simultaneously serving as both senders and routers for other nodes. Therefore, how to route packets through reliable paths becomes a fundamental problems when behaviors of certain nodes deviate from wireless ad hoc routing protocols. We proposed a novel Dirichlet reputation model based on Bayesian inference theory which evaluates reliability of each node in terms of packet delivery. Our system offers a way to predict and select a reliable path through combination of first-hand observation and second-hand reputation reports. We also proposed moving window mechanism which helps to adjust ours responsiveness of our system to changes of node behaviors. We integrated the Dirichlet reputation into routing protocol of wireless ad hoc networks. Our extensive simulation indicates that our proposed reputation system can improve good throughput of the network and reduce negative impacts caused by misbehaving nodes.

  17. Systematic lossy error protection for video transmission over wireless ad hoc networks

    NASA Astrophysics Data System (ADS)

    Zhu, Xiaoqing; Rane, Shantanu; Girod, Bernd

    2005-07-01

    Wireless ad hoc networks present a challenge for error-resilient video transmission, since node mobility and multipath fading result in time-varying link qualities in terms of packet loss ratio and available bandwidth. In this paper, we propose to use a systematic lossy error protection (SLEP) scheme for video transmission over wireless ad hoc networks. The transmitted video signal has two parts-a systematic portion consisting of a video sequence transmitted without channel coding over an error-prone channel, and error protection information consisting of a bitstream generated by Wyner-Ziv encoding of the video sequence. Using an end-to-end video distortion model in conjunction with online estimates of packet loss ratio and available bandwidth, the optimal Wyner-Ziv description can be selected dynamically according to current channel conditions. The scheme can also be applied to choose one path for transmission from amongst multiple candidate routes with varying available bandwidths and packet loss ratios, so that the expected end-to-end video distortion is maximized. Experimental results of video transmission over a simulated ad hoc wireless network shows that the proposed SLEP scheme outperforms the conventional application layer FEC approach in that it provides graceful degradation of received video quality over a wider range of packet loss ratios and is less susceptible to inaccuracy in the packet loss ratio estimation.

  18. Tri-Center Analysis: Determining Measures of Trichotomous Central Tendency for the Parametric Analysis of Tri-Squared Test Results

    ERIC Educational Resources Information Center

    Osler, James Edward

    2014-01-01

    This monograph provides an epistemological rational for the design of a novel post hoc statistical measure called "Tri-Center Analysis". This new statistic is designed to analyze the post hoc outcomes of the Tri-Squared Test. In Tri-Center Analysis trichotomous parametric inferential parametric statistical measures are calculated from…

  19. Soil Property Mapping Over Large Areas Using Sparse Ad-hoc Samples

    NASA Astrophysics Data System (ADS)

    Zhu, A.; Liu, J.

    2011-12-01

    Information on spatial variation of soil properties over large areas is a critical input for environmental modeling at large scales. Yet, quality information on soil spatial variation over large areas is difficult to obtain due to the large number of field samples required. Existing samples are often sparse and ad-hoc. The soil property maps created from these samples using existing techniques are not only at low quality but also lack the uncertainty information. This paper presents a new approach to map soil properties and quantify uncertainty in the derived soil property maps over large areas using sparse and ad-hoc samples. The underlying assumption of this new approach is the soil-landscape concept which stipulates that the more similar the environment conditions between two locations the more similar the soil property values are between the two sites. Under this assumption each sample can be considered as a representative over areas of similar environmental conditions. The level of representation of an individual sample for an unsampled location can be approximated by the similarity between their respective environment conditions. Based on this "individual representation" concept and with a Case-based Reasoning (CBR) approach soil property values at unsampled locations can be predicted and the uncertainty associated with each prediction can also be quantified based on their environmental similarity to individual samples. A case study over the Illy Region, a 50,000 km2 area in Xinjiang, Northwest China, has demonstrated that the approach can be an effective alternative for mapping soil property and quantifying uncertainty over large areas with sparse and ad-hoc samples.

  20. Dynamic autonomous routing technology for IP-based satellite ad hoc networks

    NASA Astrophysics Data System (ADS)

    Wang, Xiaofei; Deng, Jing; Kostas, Theresa; Rajappan, Gowri

    2014-06-01

    IP-based routing for military LEO/MEO satellite ad hoc networks is very challenging due to network and traffic heterogeneity, network topology and traffic dynamics. In this paper, we describe a traffic priority-aware routing scheme for such networks, namely Dynamic Autonomous Routing Technology (DART) for satellite ad hoc networks. DART has a cross-layer design, and conducts routing and resource reservation concurrently for optimal performance in the fluid but predictable satellite ad hoc networks. DART ensures end-to-end data delivery with QoS assurances by only choosing routing paths that have sufficient resources, supporting different packet priority levels. In order to do so, DART incorporates several resource management and innovative routing mechanisms, which dynamically adapt to best fit the prevailing conditions. In particular, DART integrates a resource reservation mechanism to reserve network bandwidth resources; a proactive routing mechanism to set up non-overlapping spanning trees to segregate high priority traffic flows from lower priority flows so that the high priority flows do not face contention from low priority flows; a reactive routing mechanism to arbitrate resources between various traffic priorities when needed; a predictive routing mechanism to set up routes for scheduled missions and for anticipated topology changes for QoS assurance. We present simulation results showing the performance of DART. We have conducted these simulations using the Iridium constellation and trajectories as well as realistic military communications scenarios. The simulation results demonstrate DART's ability to discriminate between high-priority and low-priority traffic flows and ensure disparate QoS requirements of these traffic flows.

  1. SARA: a self-adaptive and resource-aware approach towards secure wireless ad hoc and sensor networks

    NASA Astrophysics Data System (ADS)

    Chigan, Chunxiao; Li, Leiyuan

    2005-05-01

    Providing security is essential for mission critical Wireless Ad Hoc and Sensor Networks (WAHSN) applications. Often a highly secure mechanism inevitably consumes a rather large amount of system resources, which in turn may unintentionally cause a Security Service Denial of Service (SSDoS) attack. This paper proposes a self-adaptive resource-aware (SARA) security provisioning approach for WAHSNs. For resource scarce WAHSNs, SARA strives to provide the optimal tradeoff between the sufficient security (which is reflected by the Security Index (SI)) and the acceptable network performance degradation (which is reflected by the Performance Index (PI)). With the support of the offline optimal secure protocol selection module and the online self-adaptive security control module, SARA is capable of employing different combinations of secure protocol sets to satisfy different security need at different condition for different applications. To determine the security index SI of a secure protocol set, a heuristic cross-layer security-service mapping mechanism is presented. Furthermore, we evaluate performance index PI of a secure protocol set via simulation followed by Analysis of Variance (ANOVA). Consequently, the proposed self-adaptive security provisioning based on both SI and PI achieves the maximum overall network security services and network performance services, without causing the SSDoS attack. Furthermore, this self-adaptive mechanism is capable of switching from one secure protocol set to another while keeping similar level of security and performance, it thus provides additional security by security service hopping.

  2. Panel Discussion : Report of the APS Ad-Hoc Committee on LGBT Issues

    NASA Astrophysics Data System (ADS)

    Atherton, Tim; Barthelemy, Ramon; Garmon, Savannah; Reeves, Kyle; APS Ad-Hoc Committee on LGBT Issues Team

    Following the presentation of the findings and recommendations of the APS Ad-Hoc Committee on LGBT Issues (C-LGBT) by Committee Chair Michael Falk, a panel discussion will be held featuring several members of the committee. The discussion will focus on how APS can best ensure the recommendations of the committee are carried out in a timely fashion and other ideas on future APS efforts toward LGBT inclusion in physics. Discussion topics will also include the research and other input that shaped the committee's findings and recommendations.

  3. Joint Random Access and Power Control Game in Ad Hoc Networks with Noncooperative Users

    NASA Astrophysics Data System (ADS)

    Long, Chengnian; Guan, Xinping

    We consider a distributed joint random access and power control scheme for interference management in wireless ad hoc networks. To derive decentralized solutions that do not require any cooperation among the users, we formulate this problem as non-cooperative joint random access and power control game, in which each user minimizes its average transmission cost with a given rate constraint. Using supermodular game theory, the existence and uniqueness of Nash equilibrium are established. Furthermore, we present an asynchronous distributed algorithm to compute the solution of the game based on myopic best response updates, which converges to Nash equilibrium globally.

  4. Smart border: ad-hoc wireless sensor networks for border surveillance

    NASA Astrophysics Data System (ADS)

    He, Jun; Fallahi, Mahmoud; Norwood, Robert A.; Peyghambarian, Nasser

    2011-06-01

    Wireless sensor networks have been proposed as promising candidates to provide automated monitoring, target tracking, and intrusion detection for border surveillance. In this paper, we demonstrate an ad-hoc wireless sensor network system for border surveillance. The network consists of heterogeneously autonomous sensor nodes that distributively cooperate with each other to enable a smart border in remote areas. This paper also presents energy-aware and sleeping algorithms designed to maximize the operating lifetime of the deployed sensor network. Lessons learned in building the network and important findings from field experiments are shared in the paper.

  5. The HOCS paradigm shift from disciplinary knowledge (LOCS)--to interdisciplinary evaluative, system thinking (HOCS): what should it take in science-technology-environment-society oriented courses, curricula and assessment?

    PubMed

    Zoller, U; Scholz, R W

    2004-01-01

    Given the current world state of affairs, striving for sustainability and the consequent paradigm shift: growth-to-sustainable development, correction-to-prevention and options selection-to-options generation: the corresponding paradigm shift in science-technology-environment-society (STES) education is unavoidable. Accordingly, the essence of the current reform in STES education, worldwide, is a purposed effort to develop students' higher-order cognitive skills (HOCS) capability; i.e., question-asking, critical system thinking, decision making and problem solving, at the expense of the "delivery" of lower-order cognitive skills (LOCS)-oriented knowledge. This means a paradigm shift from the contemporary prevalent LOCS algorithmic teaching to HOCS evaluative learning and HOCS-promoting courses, curricula, teaching strategies and assessment methodologies, leading, hopefully to evaluative thinking and transfer. Following the formulation of selected relevant axioms, major paradigm shift in STES research and education for sustainability have been identified. The consequent shift, in the STES context, from disciplinary to inter- and transdisciplinary learning, in science technology and environmental engineering education is discussed, followed by selected examples of successfully implemented HOCS-promoting courses, and assessment methodologies. It is argued, that transferable "HOCS learning" for sustainability can and should be done. PMID:15193091

  6. Early (≤ 1-h) vs. late (>1-h) administration of frovatriptan plus dexketoprofen combination vs. frovatriptan monotherapy in the acute treatment of migraine attacks with or without aura: a post hoc analysis of a double-blind, randomized, parallel group study.

    PubMed

    Allais, Gianni; Bussone, Gennaro; Tullo, Vincenzo; Cortelli, Pietro; Valguarnera, Fabio; Barbanti, Piero; Sette, Giuliano; Frediani, Fabio; D'Arrigo, Giacomo; d'Onofrio, Florindo; Comi, Giancarlo; Curone, Marcella; Colombo, Bruno; Omboni, Stefano; Benedetto, Chiara

    2015-05-01

    The early use of triptan in combination with a nonsteroidal anti-inflammatory drug after headache onset may improve the efficacy of acute migraine treatment. In this retrospective analysis of a randomized, double-blind, parallel group study, we assessed the efficacy of early or late intake of frovatriptan 2.5 mg + dexketoprofen 25 or 37.5 mg (FroDex 25 and FroDex 37.5) vs. frovatriptan 2.5 mg alone (Frova) in the acute treatment of migraine attacks. In this double-blind, randomized parallel group study 314 subjects with acute migraine with or without aura were randomly assigned to Frova, FroDex 25, or FroDex 37.5. Pain free (PF) at 2-h (primary endpoint), PF at 4-h and pain relief (PR) at 2 and 4-h, speed of onset at 60, 90, 120 and 240-min, and sustained pain free (SPF) at 24-h were compared across study groups according to early (≤1-h; n = 220) or late (>1-h; n = 59) intake. PF rates at 2 and 4-h were significantly larger with FroDex 37.5 vs. Frova (early intake, n = 71 FroDex 37.5 and n = 75 Frova: 49 vs. 32 % and 68 vs. 52 %, p < 0.05; late intake, n = 20 Frodex 37.5, and n = 18 Frova: 55 vs. 17 %, p < 0.05 and 85 vs. 28 %, p < 0.01). Also with FroDex 25, in the early intake group (n = 74) PF episodes were significantly higher than Frova. PR at 2 and 4-h was significantly better under FroDex 37.5 than Frova (95 % vs. 50 %, p < 0.001, 100 % vs. 72 %, p < 0.05) in the late intake group (n = 21). SPF episodes at 24-h after early dosing were 25 % (Frova), 45 % (FroDex 25) and 41 % (FroDex 37.5, p < 0.05 combinations vs. monotherapy), whereas they were not significantly different with late intake. All treatments were equally well tolerated. FroDex was similarly effective regardless of intake timing from headache onset. PMID:26017535

  7. Add HOC?: dendritic nonlinearities shape higher-than-pairwise correlations and improve coding in noisy (spiking) neural populations

    NASA Astrophysics Data System (ADS)

    Zylberberg, Joel; Shea-Brown, Eric

    2013-03-01

    Recent experiments with relatively large neural populations show significant higher-order correlations (HOC): the data are poorly fit by pair-wise maximum entropy models, but well-fit by higher-order models. We seek to understand how HOC are shaped by the properties of networks and of the neurons therein, and how these HOC affect population coding. In our presentation, we will demonstrate that dendritic non-linearities similar to those observed in physiology experiments are equivalent to beyond-pairwise interactions in a spin-glass-type statistical model: they can either increase, or decrease, the magnitude of the HOC relative to the pair-wise correlations. We will then discuss a population coding model with parameterized pairwise- and higher-order interactions, revealing the conditions under which the beyond-pairwise interactions (dendritic nonlinearities) can increase the mutual information between a given set of stimuli, and the population responses. For jointly Gaussian stimuli, coding performance can be slightly improved by shaping the output HOC via dendritic nonlinearities, if the neural firing rates are low. For skewed stimulus distributions, like the distribution of luminance values in natural images, the performance gains are much larger. This work was supported by NSF grant DMS-1056125 and a Career Award at the Scientific Interface from the Burroughs-Wellcome Fund.

  8. Distinguishing congestion from malicious behavior in mobile ad-hoc networks

    NASA Astrophysics Data System (ADS)

    Ding, Jin; Medidi, Sirisha R.

    2004-08-01

    Packet dropping in Mobile Ad-hoc Networks could be a result of wireless link errors, congestion, or malicious packet drop attack. Current techniques for detecting malicious behavior either do not consider congestion in the network or are not able to detect in real time. Further more, they usually work at network layer. In this paper, we propose a TCP-Manet protocol, which reacts to congestion like TCP Reno protocol, and has additional capability to distinguish among congestion, wireless link error, and malicious packet drop attack. It is an end-to-end mechanism that does not require additional modifications to the nodes in the network. Since it is an extension of existing TCP protocol, it is compatible with existing protocols. It works in conjunction with the network layer and an unobtrusive monitor to assist the network in the detection and characterization of the nature of the behavior. Experimental results show that TCP-Manet has the same performance as that of TCP-Reno in wired network, and performs better in wireless ad-hoc networks in terms of throughput while having good detection effectiveness.

  9. A Secure 3-Way Routing Protocols for Intermittently Connected Mobile Ad Hoc Networks

    PubMed Central

    Parasuraman, Ganesh Kumar

    2014-01-01

    The mobile ad hoc network may be partially connected or it may be disconnected in nature and these forms of networks are termed intermittently connected mobile ad hoc network (ICMANET). The routing in such disconnected network is commonly an arduous task. Many routing protocols have been proposed for routing in ICMANET since decades. The routing techniques in existence for ICMANET are, namely, flooding, epidemic, probabilistic, copy case, spray and wait, and so forth. These techniques achieve an effective routing with minimum latency, higher delivery ratio, lesser overhead, and so forth. Though these techniques generate effective results, in this paper, we propose novel routing algorithms grounded on agent and cryptographic techniques, namely, location dissemination service (LoDiS) routing with agent AES, A-LoDiS with agent AES routing, and B-LoDiS with agent AES routing, ensuring optimal results with respect to various network routing parameters. The algorithm along with efficient routing ensures higher degree of security. The security level is cited testing with respect to possibility of malicious nodes into the network. This paper also aids, with the comparative results of proposed algorithms, for secure routing in ICMANET. PMID:25136697

  10. Intelligent QoS routing algorithm based on improved AODV protocol for Ad Hoc networks

    NASA Astrophysics Data System (ADS)

    Huibin, Liu; Jun, Zhang

    2016-04-01

    Mobile Ad Hoc Networks were playing an increasingly important part in disaster reliefs, military battlefields and scientific explorations. However, networks routing difficulties are more and more outstanding due to inherent structures. This paper proposed an improved cuckoo searching-based Ad hoc On-Demand Distance Vector Routing protocol (CSAODV). It elaborately designs the calculation methods of optimal routing algorithm used by protocol and transmission mechanism of communication-package. In calculation of optimal routing algorithm by CS Algorithm, by increasing QoS constraint, the found optimal routing algorithm can conform to the requirements of specified bandwidth and time delay, and a certain balance can be obtained among computation spending, bandwidth and time delay. Take advantage of NS2 simulation software to take performance test on protocol in three circumstances and validate the feasibility and validity of CSAODV protocol. In results, CSAODV routing protocol is more adapt to the change of network topological structure than AODV protocol, which improves package delivery fraction of protocol effectively, reduce the transmission time delay of network, reduce the extra burden to network brought by controlling information, and improve the routing efficiency of network.

  11. Stable nitrogen isotope ratios and accumulation of various HOCs in northern Baltic aquatic food chains

    SciTech Connect

    Broman, D.; Axelman, J.; Bergqvist, P.A.; Naef, C.; Rolff, C.; Zebuehr, Y.

    1995-12-31

    Ratios of naturally occurring stable isotopes of nitrogen ({delta}{sup 15}N) can be used to numerically classify trophic levels of organisms in food chains. By combining analyses results of various HOCs (e.g. PCDD/Fs, PCBs, DDTs, HCHs and some other pesticides) the biomagnification of these substances can be quantitatively estimated. In this paper different pelagic and benthic northern Baltic food chains were studied. The {delta}{sup 15}N-data gave food chain descriptions qualitatively consistent with previous conceptions of trophic arrangements in the food chains. The different HOCs concentrations were plotted versus the {delta}{sup 15}N-values for the different trophic levels and an exponential model of the form e{sup (A+B*{delta}N)} was fitted to the data. The estimates of the constant B in the model allows for an estimation of a biomagnification power (B) of different singular, or groups of, contaminants. A B-value around zero indicates that a substance is flowing through the food chain without being magnified, whereas a value > 0 indicates that a substance is biomagnified. Negative B-values indicate that a substance is not taken up or is metabolized. The A-term of the expression is only a scaling factor depending on the background level of the contaminant.

  12. Linking Satellites Via Earth "Hot Spots" and the Internet to Form Ad Hoc Constellations

    NASA Technical Reports Server (NTRS)

    Mandl, Dan; Frye, Stu; Grosvenor, Sandra; Ingram, Mary Ann; Langley, John; Miranda, Felix; Lee, Richard Q.; Romanofsky, Robert; Zaman, Afoz; Popovic, Zoya

    2004-01-01

    As more assets are placed in orbit, opportunities emerge to combine various sets of satellites in temporary constellations to perform collaborative image collections. Often, new operations concepts for a satellite or set of satellites emerge after launch. To the degree with which new space assets can be inexpensively and rapidly integrated into temporary or "ad hoc" constellations, will determine whether these new ideas will be implemented or not. On the Earth Observing 1 (EO-1) satellite, a New Millennium Program mission, a number of experiments were conducted and are being conducted to demonstrate various aspects of an architecture that, when taken as a whole, will enable progressive mission autonomy. In particular, the target architecture will use adaptive ground antenna arrays to form, as close as possible, the equivalent of wireless access points for low earth orbiting satellites. Coupled with various ground and flight software and the Internet. the architecture enables progressive mission autonomy. Thus, new collaborative sensing techniques can be implemented post-launch. This paper will outline the overall operations concept and highlight details of both the research effort being conducted in hoc constellations, mission autonomy and

  13. Energy-Aware Multipath Routing Scheme Based on Particle Swarm Optimization in Mobile Ad Hoc Networks

    PubMed Central

    Robinson, Y. Harold; Rajaram, M.

    2015-01-01

    Mobile ad hoc network (MANET) is a collection of autonomous mobile nodes forming an ad hoc network without fixed infrastructure. Dynamic topology property of MANET may degrade the performance of the network. However, multipath selection is a great challenging task to improve the network lifetime. We proposed an energy-aware multipath routing scheme based on particle swarm optimization (EMPSO) that uses continuous time recurrent neural network (CTRNN) to solve optimization problems. CTRNN finds the optimal loop-free paths to solve link disjoint paths in a MANET. The CTRNN is used as an optimum path selection technique that produces a set of optimal paths between source and destination. In CTRNN, particle swarm optimization (PSO) method is primly used for training the RNN. The proposed scheme uses the reliability measures such as transmission cost, energy factor, and the optimal traffic ratio between source and destination to increase routing performance. In this scheme, optimal loop-free paths can be found using PSO to seek better link quality nodes in route discovery phase. PSO optimizes a problem by iteratively trying to get a better solution with regard to a measure of quality. The proposed scheme discovers multiple loop-free paths by using PSO technique. PMID:26819966

  14. Opportunistic Hybrid Transport Protocol (OHTP) for Cognitive Radio Ad Hoc Sensor Networks.

    PubMed

    Bin Zikria, Yousaf; Nosheen, Summera; Ishmanov, Farruh; Kim, Sung Won

    2015-01-01

    The inefficient assignment of spectrum for different communications purposes, plus technology enhancements and ever-increasing usage of wireless technology is causing spectrum scarcity. To address this issue, one of the proposed solutions in the literature is to access the spectrum dynamically or opportunistically. Therefore, the concept of cognitive radio appeared, which opens up a new research paradigm. There is extensive research on the physical, medium access control and network layers. The impact of the transport layer on the performance of cognitive radio ad hoc sensor networks is still unknown/unexplored. The Internet's de facto transport protocol is not well suited to wireless networks because of its congestion control mechanism. We propose an opportunistic hybrid transport protocol for cognitive radio ad hoc sensor networks. We developed a new congestion control mechanism to differentiate true congestion from interruption loss. After such detection and differentiation, we propose methods to handle them opportunistically. There are several benefits to window- and rate-based protocols. To exploit the benefits of both in order to enhance overall system performance, we propose a hybrid transport protocol. We empirically calculate the optimal threshold value to switch between window- and rate-based mechanisms. We then compare our proposed transport protocol to Transmission Control Protocol (TCP)-friendly rate control, TCP-friendly rate control for cognitive radio, and TCP-friendly window-based control. We ran an extensive set of simulations in Network Simulator 2. The results indicate that the proposed transport protocol performs better than all the others. PMID:26694396

  15. Greedy data transportation scheme with hard packet deadlines for wireless ad hoc networks.

    PubMed

    Lee, HyungJune

    2014-01-01

    We present a greedy data transportation scheme with hard packet deadlines in ad hoc sensor networks of stationary nodes and multiple mobile nodes with scheduled trajectory path and arrival time. In the proposed routing strategy, each stationary ad hoc node en route decides whether to relay a shortest-path stationary node toward destination or a passing-by mobile node that will carry closer to destination. We aim to utilize mobile nodes to minimize the total routing cost as far as the selected route can satisfy the end-to-end packet deadline. We evaluate our proposed routing algorithm in terms of routing cost, packet delivery ratio, packet delivery time, and usability of mobile nodes based on network level simulations. Simulation results show that our proposed algorithm fully exploits the remaining time till packet deadline to turn into networking benefits of reducing the overall routing cost and improving packet delivery performance. Also, we demonstrate that the routing scheme guarantees packet delivery with hard deadlines, contributing to QoS improvement in various network services. PMID:25258736

  16. Energy-Aware Multipath Routing Scheme Based on Particle Swarm Optimization in Mobile Ad Hoc Networks.

    PubMed

    Robinson, Y Harold; Rajaram, M

    2015-01-01

    Mobile ad hoc network (MANET) is a collection of autonomous mobile nodes forming an ad hoc network without fixed infrastructure. Dynamic topology property of MANET may degrade the performance of the network. However, multipath selection is a great challenging task to improve the network lifetime. We proposed an energy-aware multipath routing scheme based on particle swarm optimization (EMPSO) that uses continuous time recurrent neural network (CTRNN) to solve optimization problems. CTRNN finds the optimal loop-free paths to solve link disjoint paths in a MANET. The CTRNN is used as an optimum path selection technique that produces a set of optimal paths between source and destination. In CTRNN, particle swarm optimization (PSO) method is primly used for training the RNN. The proposed scheme uses the reliability measures such as transmission cost, energy factor, and the optimal traffic ratio between source and destination to increase routing performance. In this scheme, optimal loop-free paths can be found using PSO to seek better link quality nodes in route discovery phase. PSO optimizes a problem by iteratively trying to get a better solution with regard to a measure of quality. The proposed scheme discovers multiple loop-free paths by using PSO technique. PMID:26819966

  17. Greedy Data Transportation Scheme with Hard Packet Deadlines for Wireless Ad Hoc Networks

    PubMed Central

    Lee, HyungJune

    2014-01-01

    We present a greedy data transportation scheme with hard packet deadlines in ad hoc sensor networks of stationary nodes and multiple mobile nodes with scheduled trajectory path and arrival time. In the proposed routing strategy, each stationary ad hoc node en route decides whether to relay a shortest-path stationary node toward destination or a passing-by mobile node that will carry closer to destination. We aim to utilize mobile nodes to minimize the total routing cost as far as the selected route can satisfy the end-to-end packet deadline. We evaluate our proposed routing algorithm in terms of routing cost, packet delivery ratio, packet delivery time, and usability of mobile nodes based on network level simulations. Simulation results show that our proposed algorithm fully exploits the remaining time till packet deadline to turn into networking benefits of reducing the overall routing cost and improving packet delivery performance. Also, we demonstrate that the routing scheme guarantees packet delivery with hard deadlines, contributing to QoS improvement in various network services. PMID:25258736

  18. New efficiency algorithm for flooding the packet in wireless ad hoc networks

    NASA Astrophysics Data System (ADS)

    Lee, Kyuhwan; Ma, Joongsoo

    2002-08-01

    This paper proposes a novel flooding algorithm based on an existing IEEE 802.11 MAC protocol in wireless ad hoc networks. Currently when we use the multi-hop routing algorithm, such as the Ad hoc On-demand Distance Vector (AODV) algorithm, the Cluster-Based Routing Protocol (CBRP) and so on, we frequently use the broadcast packet in order to get the topology information. At this time all nodes receiving the packet try to forward the received packet to other nodes. If a number of nodes are located in the sender's coverage, the channel is busy due to the delivery of the received packet. With respect to the coverage of the IEEE 802.11, the utilization factor of the wireless network is decreased because of occupying the channel to distribute the received packet. Thus we propose the new algorithm to resolve this problem. In this algorithm, each node maintains a table of immediate neighbors as well as each neighbor's neighbors. When each node receiving broadcast packets in the sender's coverage forwards the packets, it decides whether to forward them or not by comparing the neighbor list of receiver with that of sender. The proposed algorithm can increase the network efficiency due to the decrease in frequency of broadcast packets in the multi-hop routing protocol. Finally, we evaluate the improved performance through the simulation.

  19. A secure 3-way routing protocols for intermittently connected mobile ad hoc networks.

    PubMed

    Sekaran, Ramesh; Parasuraman, Ganesh Kumar

    2014-01-01

    The mobile ad hoc network may be partially connected or it may be disconnected in nature and these forms of networks are termed intermittently connected mobile ad hoc network (ICMANET). The routing in such disconnected network is commonly an arduous task. Many routing protocols have been proposed for routing in ICMANET since decades. The routing techniques in existence for ICMANET are, namely, flooding, epidemic, probabilistic, copy case, spray and wait, and so forth. These techniques achieve an effective routing with minimum latency, higher delivery ratio, lesser overhead, and so forth. Though these techniques generate effective results, in this paper, we propose novel routing algorithms grounded on agent and cryptographic techniques, namely, location dissemination service (LoDiS) routing with agent AES, A-LoDiS with agent AES routing, and B-LoDiS with agent AES routing, ensuring optimal results with respect to various network routing parameters. The algorithm along with efficient routing ensures higher degree of security. The security level is cited testing with respect to possibility of malicious nodes into the network. This paper also aids, with the comparative results of proposed algorithms, for secure routing in ICMANET. PMID:25136697

  20. Bioavailability of HOC depending on the colloidal state of humic substances: a case study with PCB-77 and Daphnia magna.

    PubMed

    Gallé, T; Grégoire, Ch; Wagner, M; Bierl, R

    2005-10-01

    Condensed organic matter with higher affinity for hydrophobic organic compounds (HOC) is currently held responsible for slow desorption and concomitant lower bioavailabilities of HOC in sediments and soils. In an experiment with Daphnia magna and IHSS Peat Humic Acid (PHA), we showed that the bioconcentration factor (BCF) of 3,3',4,4'-tetrachlorobiphenyl (PCB-77) was directly related to the charge of the humic colloid, as predicted by the metal-humic binding model WHAM. Consistent with the type of binding to the humic acid (counter-ion accumulation vs. specific binding), increasing the concentration of Na+ and Ca2+ ions generated opposite effects on colloid charge and HOC binding by the humic acid. Condensation as a colloidal phenomenon in solution as well as on surfaces needs to be addressed as a contributor to lower bioavailabilities and, possibly, to slower desorption kinetics. PMID:15967482

  1. Who Should Be the Winner: A "Post Hoc" Analysis of the 2000 US Election

    ERIC Educational Resources Information Center

    Wu, D. W.

    2006-01-01

    The 2000 US presidential election between Al Gore and George W. Bush has been the most intriguing and controversial in American history. Using the Florida ballot data, Wu showed that the 2000 election result could have been reversed had the "butterfly ballot effect" been eliminated. Through a combinatorial approach, Harger concluded that Gore…

  2. Daily fluid intake and outcomes in kidney recipients: post hoc analysis from the randomized ABCAN trial.

    PubMed

    Weber, M; Berglund, D; Reule, S; Jackson, S; Matas, A J; Ibrahim, H N

    2015-03-01

    Generous and even excessive fluid intake is routinely recommended to kidney transplant recipients despite minimal evidence to support this practice. We hypothesized that increased fluid intake, ascertained by 24-h urine volume output, may adversely affect graft outcomes as it would impose an extra workload on a limited number of nephrons. Kidney transplant recipients who were randomized to losartan vs. placebo in the Angiotensin II Blockade for Chronic Allograft Nephropathy (ABCAN) trial (n = 153) underwent baseline, five-yr biopsies, and annual iothalamate glomerular filtration rate assessment. Recipients with higher urine volume at randomization had higher urinary sodium and also higher urinary protein. The proportion using diuretics or CNI based regimens were similar across urinary volume tertiles. The highest urinary volume tertile (>2.56 L/d) did not predict the development of interstitial volume doubling or end-stage renal disease (ESRD) from interstitial fibrosis/tubular atrophy (OR = 3.52, 95% CI 0.4, 31.24, p = 0.26), interstitial volume doubling or all-cause ESRD (OR = 7.04, 95% CI 0.66, 74.87, p = 0.11), and was not associated with the conventional endpoint of doubling serum creatinine, all-cause ESRD, or death (OR = 0.89, 95% CI 0.21, 3.71, p = 0.87). These results suggest that the current practice of liberal fluid intake may not be beneficial in low risk and mostly Caucasian transplant recipients. PMID:25619874

  3. Intelligent self-organization methods for wireless ad hoc sensor networks based on limited resources

    NASA Astrophysics Data System (ADS)

    Hortos, William S.

    2006-05-01

    A wireless ad hoc sensor network (WSN) is a configuration for area surveillance that affords rapid, flexible deployment in arbitrary threat environments. There is no infrastructure support and sensor nodes communicate with each other only when they are in transmission range. To a greater degree than the terminals found in mobile ad hoc networks (MANETs) for communications, sensor nodes are resource-constrained, with limited computational processing, bandwidth, memory, and power, and are typically unattended once in operation. Consequently, the level of information exchange among nodes, to support any complex adaptive algorithms to establish network connectivity and optimize throughput, not only deplete those limited resources and creates high overhead in narrowband communications, but also increase network vulnerability to eavesdropping by malicious nodes. Cooperation among nodes, critical to the mission of sensor networks, can thus be disrupted by the inappropriate choice of the method for self-organization. Recent published contributions to the self-configuration of ad hoc sensor networks, e.g., self-organizing mapping and swarm intelligence techniques, have been based on the adaptive control of the cross-layer interactions found in MANET protocols to achieve one or more performance objectives: connectivity, intrusion resistance, power control, throughput, and delay. However, few studies have examined the performance of these algorithms when implemented with the limited resources of WSNs. In this paper, self-organization algorithms for the initiation, operation and maintenance of a network topology from a collection of wireless sensor nodes are proposed that improve the performance metrics significant to WSNs. The intelligent algorithm approach emphasizes low computational complexity, energy efficiency and robust adaptation to change, allowing distributed implementation with the actual limited resources of the cooperative nodes of the network. Extensions of the

  4. Energy-efficient distributed constructions of miniumum spanning tree for wireless ad-hoc networks

    SciTech Connect

    Kumar, V. S. A.; Pandurangan, G.; Khan, M.

    2004-01-01

    The Minimum Spanning Tree (MST) problem is one of the most important and commonly occurring primitive in the design and operation of data and communication networks. While there a redistributed algorithms for the MST problem these require relatively large number of messages and time, and are fairly involved, require synchronization and a lot of book keeping; this makes these algorithms impractical for emerging technologies such as ad hoc and sensor networks. In such networks, a sensor has very limited power, and any algorithm needs to be simple, local and energy efficient for being practical. Motivated by these considerations, we study the performance of a class of simple and local algorithms called Nearest Neighbor Tree (NNT) algorithms for energy-efficient construction of MSTs in a wireless ad hoc setting. These employ a very simple idea to eliminate the work involved in cycle detection in other MST algorithms: each node chooses a distinct rank, and connects to the closest node of higher rank. We consider two variants of the NNT algorithms, obtained by two ways of choosing the ranks: (i) Random NNT, in which each node chooses a rank randomly, and (ii) Directional NNT, in which each node uses directional information for choosing the rank. We show provable bounds on the performance of these algorithms in instances obtained by uniformly distributed points in the unit square. Finally, we perform extensive simulations of our algorithms. We tested our algorithms on both uniformly random distributions of points, and on realistic distributions of points in an urban setting. The cost of the tree found by the NNT algorithms is within a factor of 2 of the MST, but there is more than a ten-fold saving on the energy and about a five fold saving on the number of messages sent. Also, our algorithms are significantly simpler to implement compared to, for instance, the GHS algorithm, which is essentially optimal with regards to the message complexity. Thus, our results

  5. Criteria for intraventricular conduction disturbances and pre-excitation. World Health Organizational/International Society and Federation for Cardiology Task Force Ad Hoc.

    PubMed

    Willems, J L; Robles de Medina, E O; Bernard, R; Coumel, P; Fisch, C; Krikler, D; Mazur, N A; Meijler, F L; Mogensen, L; Moret, P

    1985-06-01

    In an effort to standardize terminology and criteria for clinical electrocardiography, and as a follow-up of its work on definitions of terms related to cardiac rhythm, an Ad Hoc Working Group established by the World Health Organization and the International Society and Federation of Cardiology reviewed criteria for the diagnosis of conduction disturbances and pre-excitation. Recommendations resulting from these discussions are summarized for the diagnosis of complete and incomplete right and left bundle branch block, left anterior and left posterior fascicular block, nonspecific intraventricular block, Wolff-Parkinson-White syndrome and related pre-excitation patterns. Criteria for intraatrial conduction disturbances are also briefly reviewed. The criteria are described in clinical terms. A concise description of the criteria using formal Boolean logic is given in the Appendix. For the incorporation into computer electrocardiographic analysis programs, the limits of some interval measurements may need to be adjusted. PMID:3889097

  6. On the Connectivity, Lifetime and Hop Count of Routes Determined Using the City Section and Manhattan Mobility Models for Vehicular Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Meghanathan, Natarajan

    The high-level contribution of this paper is a simulation based analysis of the network connectivity, hop count and lifetime of the routes determined for vehicular ad hoc networks (VANETs) using the City Section and Manhattan mobility models. The Random Waypoint mobility model is used as a benchmark in the simulation studies. Two kinds of paths are determined on the sequence of static graphs representing the topology over the duration of the network session: paths with the minimum hop count (using the Dijkstra algorithm) and stable paths with the longest lifetime (using our recently proposed OptPathTrans algorithm). Simulation results indicate that the City Section model provided higher network connectivity compared to the Manhattan model for all the network scenarios. Minimum hop paths and stable paths determined under the Manhattan model have a smaller lifetime and larger hop count compared to those determined using the City Section and Random Waypoint mobility models.

  7. CP-TDMA: Coloring-and Probability-Based TDMA Scheduling for Wireless Ad Hoc Networks

    NASA Astrophysics Data System (ADS)

    Zhang, Xuedan; Hong, Jun; Zhang, Lin; Shan, Xiuming; Li, Victor O. K.

    This paper addresses the issue of transmission scheduling in wireless ad hoc networks. We propose a Time Division Multiple Access (TDMA) scheduling scheme based on edge coloring and probabilistic assignment, called CP-TDMA. We categorize the conflicts suffered by wireless links into two types: explicit conflicts and implicit conflicts, and utilize two different strategies to deal with them. Explicit conflicts are avoided completely by a simple distributed edge-coloring algorithm μ-M, and implicit conflicts are minimized by applying probabilistic time slot assignments to links. We evaluate CP-TDMA analytically and numerically, and find that CP-TDMA, which requires only local information exhibits a better performance than previous work.

  8. Robotic disaster recovery efforts with ad-hoc deployable cloud computing

    NASA Astrophysics Data System (ADS)

    Straub, Jeremy; Marsh, Ronald; Mohammad, Atif F.

    2013-06-01

    Autonomous operations of search and rescue (SaR) robots is an ill posed problem, which is complexified by the dynamic disaster recovery environment. In a typical SaR response scenario, responder robots will require different levels of processing capabilities during various parts of the response effort and will need to utilize multiple algorithms. Placing these capabilities onboard the robot is a mediocre solution that precludes algorithm specific performance optimization and results in mediocre performance. Architecture for an ad-hoc, deployable cloud environment suitable for use in a disaster response scenario is presented. Under this model, each service provider is optimized for the task and maintains a database of situation-relevant information. This service-oriented architecture (SOA 3.0) compliant framework also serves as an example of the efficient use of SOA 3.0 in an actual cloud application.

  9. Energy conservation in ad hoc multimedia networks using traffic-shaping mechanisms

    NASA Astrophysics Data System (ADS)

    Chandra, Surendar

    2003-12-01

    In this work, we explore network traffic shaping mechanisms that deliver packets at pre-determined intervals; allowing the network interface to transition to a lower power consuming sleep state. We focus our efforts on commodity devices, IEEE 802.11b ad hoc mode and popular streaming formats. We argue that factors such as the lack of scheduling clock phase synchronization among the participants and scheduling delays introduced by back ground tasks affect the potential energy savings. Increasing the periodic transmission delays to transmit data infrequently can offset some of these effects at the expense of flooding the wireless channel for longer periods of time; potentially increasing the time to acquire the channel for non-multimedia traffic. Buffering mechanisms built into media browsers can mitigate the effects of these added delays from being mis-interpreted as network congestion. We show that practical implementations of such traffic shaping mechanisms can offer significant energy savings.

  10. Enhancing the Social Capital of Learning Communities by Using an Ad Hoc Transient Communities Service

    NASA Astrophysics Data System (ADS)

    Fetter, Sibren; Berlanga, Adriana J.; Sloep, Peter

    In online learning, communities can help to enhance learning. However, because of the dynamic nature of communities, attaining and sustaining these communities can be difficult. One aspect that has an influence on, and is influenced by these dynamics is the social capital of a community. Features of social capital are the social network structure, the sense of belonging and, the support received and provided. It is hypothesized that these features can be improved by using Ad Hoc Transient Communities (AHTCs). Through an AHTC learners are brought together for a specific, learning-related goal (‘ad hoc’) and for only a limited amount of time (‘transience’). To test whether the use of AHTCs has a positive influence on the social capital, a learner support service which enables the use of AHTCs is proposed. Furthermore, requirements, prerequisites, and future research are discussed.