Synchronous Node Research Articles

Novel Model of Wireless Sensor with Indoor Positioning Algorithm and Time Synchronization Protocol

This paper describes the positioning based on ZigBee network, and it provides location indoor information and node state alarm information. Wireless sensor indoor positioning system consists of 3 types nodes: the coordinator node, reference node and blind. Time synchronization protocol is an efficient synchronization technology star network structure, synchronization to the gateway node as a starting point, each cluster head node synchronization tree network structure. The paper presents novel model of wireless sensor indoor positioning algorithm and time synchronization protocol. Experiments show that the design of indoor positioning system can meet requirement function and performance of nodes positioning system.

Abstract 985: The mutational landscape of LN metastasis and recurrence in HNSCC

Abstract Recent whole exome sequencing (WES) studies have reported the mutations that characterize primary head and neck squamous cell carcinomas (HNSCC). While exposure to tobacco, alcohol and HPV infection are known to contribute to HNSCC development and prognosis, the largest obstacle to long term survival is recurrent and metastatic disease. Approximately 50% of patients present with synchronous lymph node metastases (SLNM), where 5-year adjusted survival is ≈85% for patients without SLNM compared with 30-60% in patients with SLNM. 20-30% of patients cured of their primary HNSCC go on to develop recurrent disease, which is usually refractory to standard therapies. Here, we report the first WES study of paired primary tumor and SLNM from 14 HNSCC patients, and paired primary tumor and metachronous loco-regional metastases (MLRM) from 11 HNSCC patients. Primary tumors averaged 67 nonsynonymous mutations per tumor (n=21), SLNM averaged 89.3 (n=12), and MLRM averaged 41.7 (n=9). TP53 was the only gene mutated in a majority (57%) of primary tumors in our cohort. We observed similar rates of mutation in several of the TCGA-defined “HNSCC signature” genes in our primary cohort, including FAT1 (14.3%) and CASP8 (4.8%), among others. While the size of our cohort does not allow for appropriately powered statistical analyses; 206 and 204 genes, were mutated in metastatic tumors, but not the respective paired primary tumors, in the SLNM and MLRM cohorts, respectively. AP2B1 and ITPR3 mutations were enriched in SLNM, as newly acquired mutations were seen in multiple (2 and 2/12) SLNM samples. GLUL and DDR2 mutations were enriched in MLRM, as newly acquired mutations were seen in multiple (2 and 2/9) MLRM samples. All 4 genes have previously been implicated in the metastatic process in other cancers. The potential enrichment of DDR2 mutations in HNSCC metastases is especially intriguing, as mutations in this gene have been shown to confer sensitivity to the SRC-family kinase inhibitor, dasatinib, in lung and breast cancer. Here we report exquisite sensitivity to dasatinib in our HNSCC preclinical models harboring DDR2 mutations, suggesting further investigation of this drug is warranted in recurrent HNSCC. Citation Format: Matthew Louis Hedberg, Gerald Goh, Maria Freilino, Yan Zeng, Vivian WY Lui, Roy S. Herbst, Richard P. Lifton, Jennifer R. Grandis. The mutational landscape of LN metastasis and recurrence in HNSCC. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 985. doi:10.1158/1538-7445.AM2014-985

CES2, ABCG2, TS and Topo-I primary and synchronous metastasis expression and clinical outcome in metastatic colorectal cancer patients treated with first-line FOLFIRI regimen.

Enzymatic activation of irinotecan (CPT-11) is due to carboxylesterase (CES), and its pharmacological behavior is influenced by drug resistance-related proteins. We previously reported that the clinical response and prognosis of metastatic colorectal cancer (mCRC) patients did not differ in tumors with different thymidylate synthase (TS) or topoisomerase-I (Topo-I) expression. Using immunohistochemistry (IHC), we evaluated the biological role of CES2 and the expression of breast cancer resistance protein (BCRP/ABCG2) in 58 consecutive mCRC patients, who had undergone a first-line CPT-11/5-FU/leucovirin (FOLFIRI) regimen. The expression of these proteins was also examined in a group of synchronous lymph nodes and liver metastases. Furthermore, all samples were revaluated for TS and Topo-I expression. High expression of CES2, ABCG2, TS and Topo-I was observed in 55%, 56%, 38% and 49% of patients, respectively. There was a significant association between high TS and high ABCG2 expression (p = 0.049). Univariate analysis showed that only TS expression significantly impacted on time to progression (p = 0.005). Moreover, Cox’ multivariate analysis revealed that TS expression was significantly associated with overall survival (p = 0.01). No significant correlation was found between investigated markers expression and clinical response. Topo-I expression resulted in being significantly higher in liver metastases with respect to the corresponding primary tumors (p < 0.0001), emphasizing the role of Topo-I expression in metastatic cancer biology. In primary tumor tissues, CES2 expression tended to be higher than that observed in liver metastasis tissues (p = 0.05). These preliminary data may suggest CES2 over-expression as a potential marker of malignant phenotype. In light of these findings, we suggest that Topo-I expression together with TS expression could be associated with metastatic progression of CRC. Further studies are warranted with the aim of evaluating the potential predictive and prognostic role of CES2 and ABCG2 in larger series of patients.

Combinatorial synchronization of complex multiple networks with unknown parameters

In this paper, a combinatorial inner synchronization within a sub-network, which consists of four-wing chaotic system with unknown parameters and external disturbances as node dynamics, and a combinatorial outer synchronization between different sub-networks are investigated. Based on the Lyapunov stability theory, LaSalle’s invariance principle, cluster analysis, and pinning control technique, some sufficient conditions, which can ensure not only the combinatorial inner synchronization of the nodes with identical node dynamics in a sub-network, but also the combinatorial outer synchronization of the sink nodes with identical or nonidentical ones between different sub-networks by a suitable switch control scheme, are obtained. By using the pinning control, only the sink node within a sub-network which has direct connections to the sink nodes in other sub-networks needs to be controlled. Finally, some numerical simulations are presented to demonstrate the feasibility and validity of the obtained results by taking the star-like topological structure as an example.

Predictable nonwandering localization of covariant Lyapunov vectors and cluster synchronization in scale-free networks of chaotic maps.

Covariant Lyapunov vectors for scale-free networks of Hénon maps are highly localized. We revealed two mechanisms of the localization related to full and phase cluster synchronization of network nodes. In both cases the localization nodes remain unaltered in the course of the dynamics, i.e., the localization is nonwandering. Moreover, this is predictable: The localization nodes are found to have specific dynamical and topological properties and they can be found without computing of the covariant vectors. This is an example of explicit relations between the system topology, its phase-space dynamics, and the associated tangent-space dynamics of covariant Lyapunov vectors.

Algebraic Solution for Joint Localization and Synchronization of Multiple Sensor Nodes in the Presence of Beacon Uncertainties

This paper addresses the problem of joint localization and synchronization of multiple sensor nodes simultaneously using the time stamp information from message exchanges between the sensor nodes and beacons and among the sensor nodes. Through parameter transformation and multi-stage processing, two computationally efficient algebraic solutions are developed for this challenging non-linear estimation problem. One is without message exchanges among the sensor nodes and the other is with the exchanges. Theoretical analysis shows that the performance of the proposed solutions is able to reach the CRLB accuracy for the sensor node positions, as well as the clock parameters over the mild error region. Simulation results support very well the theoretical performance of the proposed solutions.

PRECISE SYNCHRONISATION IN INDUSTRIAL SYSTEM USING IEEE 1588 PRECISE TIME PROTOCOL

Nowadays there is a frequent demand to increase the quality of synchronization in industrial distributed systems. Node synchronization can be implemented in the Ethernet network using time protocols, e.g. IEEE 1588 Precise Time Protocol (PTP). However, active network components like switches and routers have negative influence on achieved accuracy of synchronization because they affect a packet delay variation in the network. To suppress this effect, special (but expensive) industrial switches, with a packet propagation delay correction, can be used. Another way using either low cost GPS receivers for synchronization of local clocks or a special timing for data transfer is described in the paper. It will allow a cheaper solution that preserves high quality of synchronization. Besides, a device for packet delay measurement (PTP tester) was designed and developed to be possible to evaluate the proposed methods.

Impact of Synchronous Metastasis Distribution on Cancer Specific Survival in Renal Cell Carcinoma after Radical Nephrectomy with Tumor Thrombectomy

Metastatic renal cell carcinoma can be clinically diverse in terms of the pattern of metastatic disease and response to treatment. We studied the impact of metastasis and location on cancer specific survival. The records of 2,017 patients with renal cell cancer and tumor thrombus who underwent radical nephrectomy and tumor thrombectomy from 1971 to 2012 at 22 centers in the United States and Europe were analyzed. Number and location of synchronous metastases were compared with respect to patient cancer specific survival. Multivariable Cox regression models were used to quantify the impact of covariates. Lymph node metastasis (155) or distant metastasis (725) was present in 880 (44%) patients. Of the patients with distant disease 385 (53%) had an isolated metastasis. The 5-year cancer specific survival was 51.3% (95% CI 48.6-53.9) for the entire group. On univariable analysis patients with isolated lymph node metastasis had a significantly worse cancer specific survival than those with a solitary distant metastasis. The location of distant metastasis did not have any significant effect on cancer specific survival. On multivariable analysis the presence of lymph node metastasis, isolated distant metastasis and multiple distant metastases were independently associated with cancer specific survival. Moreover higher tumor thrombus level, papillary histology and the use of postoperative systemic therapy were independently associated with worse cancer specific survival. In our multi-institutional series of patients with renal cell cancer who underwent radical nephrectomy and tumor thrombectomy, almost half of the patients had synchronous lymph node or distant organ metastasis. Survival was superior in patients with solitary distant metastasis compared to isolated lymph node disease.

Discordance rate of HER2 status in primary breast carcinomas versus synchronous axillary lymph node metastases: a multicenter retrospective investigation

BackgroundHuman epidermal growth factor receptor 2 (HER2) is considered to be a therapeutic and prognostic marker in the management of breast carcinoma (BC), although discordance rates between primary and metastatic or locally recurrent lesions have been reported.MethodsOne hundred and forty-eight paraffin-embedded BC tissues from patients of mean age 59.27 (33–96) years and corresponding synchronous lymph node metastases were collected and retrospectively studied using immunohistochemistry and fluorescence in situ hybridization to evaluate HER2 status. Fleiss-Cohen weighted k statistics were used to assess the concordance rate between HER2 status of the primary BC and the synchronous metastatic lesions.ResultsThe overall concordance rate for HER2 was 95.28%. Eighty-nine cases were concordantly HER2-negative in primary BC and nodal metastases, and 52 cases were HER2-positive in both primary and metastatic tumors. Changes in HER2 status between primary BC and corresponding synchronous metastases were observed in seven (4.72%) cases. Three of the discordant cases were HER2-negative in the primary tumor and HER2-positive in the metastases, while four cases were HER2-positive in the primary BC and HER2-negative in the metastases. No significant correlations were identified between HER2 status and expression of hormone receptors, growth fraction (Ki-67), or other histopathological parameters (pT, pN, grade).ConclusionSimultaneous determination of HER2 in BC and corresponding metastatic lymph nodes is not mandatory, but may strongly influence the therapeutic management. It was demonstrated that loss of HER2 amplification results in worse post-relapse survival and overall survival in BC patients and, on the other hand, a gain in HER2 expression in metastatic lymph nodes of BC may allow the possibility of a targeted treatment. Thus, our opinion is that significant prognostic information may be obtained by simultaneous assessment of HER2 status in both primary and synchronous metastatic BC.

No Communication Nodes Synchronization for a Low Power Consumption MAC Protocol in WSN based on IR-UWB

Synchronization is an important issue in multi hops Wireless Sensor Networks (WSN). Such networks are known by their limited resources of energy, storage, computation, and bandwidth. In addition if the networks entities are deployed with high density, it makes the synchronization mandatory for these networks. Impulse Radio Ultra Wide Band (IR-UWB) technology is a promising solution for this kind of networks due to its various advantages such as its robustness to severe multipath fading even in indoor environments, its low cost, low complexity, and low power consumption. To exploit the specific features of this technology, we need a convenient MAC protocol. WideMac was presented as a new low power consumption MAC protocol designed for WSN using IR-UWB transceivers. Because of the luck of synchronization in this protocol, this paper presents a solution for the synchronization problem especially in the case of no communication between the Network’s nodes. To implement and evaluate the proposed synchronization mechanism, we used MiXiM platform under OMNet++ Simulator.

An Enhanced Approach for Synchronization in WSN

Small, low cost, low power and multifunctional sensor are developed as a result of improvement in micro-electromechanical (MEMS) technology. Sensor's are connected via wireless medium and are used to observe various aspects of the physical world. Data sensed by these nodes needs to be ag-glomerated using data fusion, which requires clocks of nodes to be synchronized with each other. Existing approaches of clock synchronization are not designed keeping wireless sensor networks in mind. So there is a need to extend or redesign and develop a new way to synchronize the wireless sensor networks that is best suited to the specific needs of a sensor-network application. In this paper, we introduced a new approach of synchronization of nodes in WSN by enhancing the CSMA/CA protocol (slotted ALOHA). A Master Node, which is assumed to be synchronized with GPS (Global positioning System), deployed in the network. The nodes in a cluter synchronized their local clock with master node using NTP. The proposed solution features minimal energy consumption, minimal packet loss and achieve better throughput.

Precise packet delay measurement in an Ethernet network

Node synchronization can be implemented in an Ethernet network using time protocols; e.g. IEEE 1588 [1]. Active network components like switches and routers influence the accuracy of synchronization because they affect a packet delay variation in the network. Therefore, the delay is not constant and, as well, the delay in one direction is not equal to the delay in the opposite direction.This paper presents a low-cost device that can measure the packet delay with high accuracy in both communication directions and, at the same time, calculate network parameters including a packet delay variation, path asymmetry and dependency of the delay in opposite directions.The measurements can be used for the estimation of synchronization accuracy within the tested network. Some network elements have an unexpectedly large variability of path delays and large asymmetry. This behavior can be measured directly and therefore it is possible to eliminate these devices from the network. The results can be also used for the manual calibration of end nodes. It is not recommended, however, as it is vulnerable to network topology changes.

Improved UWB Wireless Sensor Network Algorithm for Human Intruder Localization

In this study we present a WSN algorithm for localization which increases efficiency in time, energy and cost of localization radar systems. The algorithm is designed using a hybrid of two widely used localization techniques, Time of Arrival (ToA) and Received Signal Strength Indicator (RSSI). The target is to achieve a design which is more efficient than RSSI and requires no nodes synchronization which is fundamental in ToA. Virtual References Tags (VRTs) play a key role in improving efficiency by providing a reference point near the target which is discussed in experimental results of WSN with four different number of VRTs and lastly a comparison of proposed with existing methods is given.

Comparison of site-specific gene expression levels in primary tumors and synchronous lymph node metastases in advanced gastric cancer

Many malignant tumors consist of heterogeneous subpopulations of cells. This heterogeneity is associated with genetic characteristics. However, it remains unclear whether gene expression levels differ among specific sites of tumors in gastric cancer. We studied differences in gene expression levels among specific sites of primary tumors and synchronous lymph node metastases, using formalin-fixed, paraffin-embedded specimens resected surgically from 48 patients with previously untreated advanced gastric cancer. Specimens were obtained by laser-captured microdissection from five regions: (1) nonneoplastic mucosa, (2) surface layer (mucosa) of the primary tumor (surface sections), (3) middle layer (submucosa) of the primary tumor (middle sections), (4) the deepest layer of the primary tumor (muscularis propria or deeper) at the site of deepest invasion (deep sections), and (5) level 1 synchronous lymph node metastasis (lymph node metastases). Expression levels of the following target genes were determined by quantitative real-time polymerase chain reaction: thymidylate synthase (TS), thymidine phosphorylase (TP), dihydropyrimidine dehydrogenase (DPD), epidermal growth factor receptor (EGFR), vascular endothelial growth factor (VEGF), and hypoxia-inducible factor-1α (HIF1α). TP, DPD, EGFR, and HIF1α gene expression levels were significantly higher in deep sections than in surface sections. TP, EGFR, VEGF, and HIF1α gene expression levels were significantly higher in lymph node metastases than in surface sections. TP, DPD, EGFR, VEGF, and HIF1α gene expression levels were positively correlated with the specific samples harvested from the tumors. Our results show that the expression levels of some genes in tumor cells can change in specific sites of tumors and can become higher in association with tumor progression.

HER2 expression in primary gastric cancers and paired synchronous lymph node and liver metastases. A possible road to target HER2 with radionuclides

Resistance has been reported to human epidermal growth factor receptor 2 (HER2)-targeted therapy with the tyrosine kinase inhibitor lapatinib and the antibody trastuzumab in metastatic gastric cancer. An alternative or complement might be to target the extracellular domain of HER2 with therapy-effective radionuclides. The fraction of patients with HER2 expression in primary tumors and major metastatic sites, e.g., lymph nodes and liver, was analyzed to evaluate the potential for such therapy. Samples from primary tumors and lymph node and liver metastases were taken from each patient within a few hours, and to our knowledge, such sampling is unique. The number of analyzed cases was therefore limited, since patients that had received preoperative radiotherapy, chemotherapy, or HER2-targeted therapy were excluded. From a large number of considered patients, only 29 could be included for HER2 analysis. Intracellular mutations were not analyzed since they are assumed to have no or minor effect on the extracellular binding of molecules that deliver radionuclides. HER2 was positive in nearly 52 % of the primary tumors, and these expressed HER2 in corresponding lymph node and liver metastases in 93 and 100 % of the cases, respectively. Similar values for primary tumors and also good concordance with metastases have been indicated in the literature. Thus, relevant radionuclides and targeting molecules for nuclear medicine-based noninvasive, whole-body receptor analysis, dose planning, and therapy can be applied for many patients; see "Discussion" Hopefully, more patients can then be treated with curative instead of palliative intention.

Two-hop time synchronization protocol for sensor networks

One of the critical middleware services for sensor networks is the time synchronization, which provides supports to different applications. Synchronization protocols used for Internet and LANs are not appropriate in the sensor networks for the high-density and limited energy resource. This paper describes two-hop time synchronization (TTS) that aims at reducing the synchronization overhead and providing more accurate network-wide synchronization. The synchronization message exchanges are minimized by making full use of sensors’ broadcast domain and enlarging the common node synchronization range in multi-hop scenarios. By halving synchronization hops, the TTS achieves high multi-hop synchronization precision. The proposed protocol contains single-hop synchronization model, multi-hop synchronization algorithm, and a power control scheme. We prove that the extension of single-hop TTS to network-wide synchronization is NP-complete. The complexity and convergence time of multi-hop TTS are analyzed in detail. We simulate TTS on MATLAB and show that it requires minimal overhead and convergence time compared with other protocols. We also implement TTS on common sensors and its multi-hop synchronization error is less than that of receiver-receiver synchronization (R-RS).

An adaptive range-free localisation protocol in wireless sensor networks

It is well known that localisation is a fundamental issue for many wireless network applications. Without the need of additional ranging devices, the range–free localisation technology is a cost–effective solution for low–cost indoor and outdoor wireless sensor networks. However, we noted that most existing algorithms were only studied using tools like MATLAB neglecting possible problems in a real wireless network context such as frame collision and node synchronisation. Thus, we propose an adaptive range–free localisation protocol (ALP) based on IEEE 802.15.4 standard, which can evaluate localisation algorithms. Using our localisation protocol, we investigate and compare the performance of our new approach to some existing range–free algorithms in terms of localisation accuracy, mobility, synchronisation and overhead. Our results show that our Mid–perpendicular, Checkout DV–hop and Selective 3–Anchor DV–hop algorithms support robust and dynamic localisation in the context of our adaptive localisation protocol.

St Gallen molecular subtypes in primary breast cancer and matched lymph node metastases - aspects on distribution and prognosis for patients with luminal A tumours: results from a prospective randomised trial

BackgroundThe St Gallen surrogate molecular subtype definitions classify the oestrogen (ER) positive breast cancer into the luminal A and luminal B subtypes according to proliferation rate and/or expression of human epidermal growth factor receptor 2 (HER2) with differences in prognosis and chemo-responsiveness. Primary tumours and lymph node metastases might represent different malignant clones, but in the clinical setting only the biomarker profile of the primary tumour is used for selection of adjuvant systemic treatment. The present study aimed to classify primary breast tumours and matched lymph node metastases into luminal A, luminal B, HER2-positive and triple-negative subtypes and compare the distributions.MethodsEighty-five patients with available tumour tissue from both locations were classified. The distribution of molecular subtypes in primary tumours and corresponding lymph node metastases were compared, and related to 5-year distant disease-free survival (DDFS).ResultsThe St Gallen molecular subtypes were discordant between primary tumours and matched lymph node metastases in 11% of the patients (p = 0.06). The luminal A subtype in the primary tumour shifted to a subtype with a worse prognostic profile in the lymph node metastases in 7 of 45 cases (16%) whereas no shift in the opposite direction was observed (0/38) (p = 0.02). All subtypes had an increased hazard for developing distant metastasis during the first 5 years after diagnosis in both primary breast tumours and matched lymph node metastases, compared with the luminal A subtype.ConclusionThe classification according to the St Gallen molecular subtypes in primary tumours and matched lymph node metastases, implicates a shift to a more aggressive subtype in synchronous lymph node metastases compared to the primary breast tumour. The selection of systemic adjuvant therapy might benefit from taking the molecular subtypes in the metastatic node into account.

The Biological Application of Synchronization Ability of Different Complex Network Structures

This paper aimed at the chaotic synchronization ability of complex networks with different structures whose nodes have different orders. Problems of complex network synchronization and biological application are introduced firstly. And then, we studied synchronization with different orders and different network structures. Based on Lyapunov stability theory, the coupling function of the connecting nodes synchronization is identified. Numerical simulation results were used to compare the synchronization ability of three kinds of network structures. So, certain biological phenomena of complex network can be explained due to our research.

Distributed Testbed for Coded Cooperation with Software-Defined Radios

Evaluating the performance of the cooperative communications using the hardware testbed in the real environment is critical for system design and promoting the potential practical applications in the future, considering the disadvantages of the theoretical analysis and simulation methods. In this paper, a distributed hardware testbed using software-defined radios is designed and implemented for cooperative communications, and the performance of two coded cooperation schemes with Turbo codes is evaluated in the physical layer. For the testbed, the fundamental point-to-point link uses the differential binary phase shift keying (DBPSK) constellations, and the physical (PHY)/media access (MAC) layer frames for the performance evaluation are devised. Furthermore, a distributed node synchronization scheme is implemented and the source node and relay node work in the time division protocol without any centralized controlling. Finally, two popular coded cooperation schemes with Turbo codes for the three-node model and the four-node model are tested in the real indoor environment. The experiment results verify the effectiveness of the testbed for system performance evaluation in the PHY layer.