Energy efficient routing in wireless sensor network based on mobile sink guided by stochastic hill climbing

In Wireless Sensor Networks (WSNs), the reduction of energy consumption in the batteries of a sensor node is an important task. Sensor nodes of WSNs perform three significant functions such as data sensing, data transmitting and data relaying. Routing technique is one of the methods to enhance the sensor nodes battery lifetime. Energy optimization is done by using one of the heuristic routing methods for sensing and transmitting the data. To enhance the energy optimization mainly concentrated on data relaying. In this work stochastic hill climbing is adapted. The proposed solution for data relaying utilizes geographical routing and mobile sink technique. The sink collects the data from cluster heads and movement of the sink is routed by stochastic hill climbing. Network simulator 2 is used for experimentation purpose. This work also compares with the existing routing protocols like Energy-efficient Low Duty Cycle (ELDC), Threshold sensitive Energy Efficient sensor Network (TEEN) and Adaptive clustering protocol. The proposed work shows promising results with respect to lifetime, average energy of nodes and packet delivery ratio

Energy efficient routing towards a mobile sink using virtual coordinates in a wireless sensor network

The existence of a coordinate system can often improve the routing in a wireless sensor network. While most coordinate systems correspond to the geometrical or geographical coordinates, in recent years researchers had proposed the use of virtual coordinates. Virtual coordinates depend only on the topology of the network as defined by the connectivity of the nodes, without requiring geographical information. The work in this thesis extends the use of virtual coordinates to scenarios where the wireless sensor network has a mobile sink. One reason to use a mobile sink is to distribute the energy consumption more evenly among the sensor nodes and thus extend the life-time of the network. We developed two algorithms, MS-DVCR and CU-DVCR which perform routing towards a mobile sink using virtual coordinates. In contrast to the baseline virtual coordinate routing MS-DVCR limits routing updates triggered by the sink movement to a local area around the sink. In contrast, CU-DVCR limits the route updates to a circular area on the boundary of the local area. We describe the design justification and the implementation of these algorithms. Using a set of experimental studies, we show that MS-DVCR and CU-DVCR achieve a lower energy consumption compared to the baseline virtual coordinate routing without any noticeable impact on routing performance. In addition, CU-DVCR provides a lower energy consumption than MS-DVCR for the case of a fast moving sink

Localized geographic routing to a mobile sink with guaranteed delivery in sensor networks

International audienceWe propose a novel localized Integrated Location Service and Routing (ILSR) scheme, based on the geographic routing protocol GFG, for data communications from sensors to a mobile sink in wireless sensor networks. The objective is to enable each sensor to maintain a slow-varying routing next hop to the sink rather than the precise knowledge of quick-varying sink position. In ILSR, sink updates location to neighboring sensors after or before a link breaks and whenever a link creation is observed. Location update relies on flooding, restricted within necessary area, where sensors experience (next hop) change in GFG routing to the sink. Dedicated location update message is additionally routed to selected nodes for prevention of routing failure. Considering both unpredictable and predictable (controllable) sink mobility, we present two versions. We prove that both of them guarantee delivery in a connected network modeled as unit disk graph. ILSR is the first localized protocol that has this property. We further propose to reduce message cost, without jeopardizing this property, by dynamically controlling the level of location update. A few add-on techniques are as well suggested to enhance the algorithm performance. We compare ILSR with an existing competing algorithm through simulation. It is observed that ILSR generates routes close to shortest paths at dramatically lower (90% lower) message cost

Isolation, cultivation and characterization of cells originating from tumor and tumor margin of patients with basal cell carcinoma in vitro

Homeostaza kože direktno zavisi od mehanizma kontinuiranog obnavljanja ćelijske populacije kože i njene sposobnosti regeneracije. U epidermisu je prisutna posebna populacija ćelija zadužena za proces samoobnavljanja kože, tzv. epidermalne matične ćelije koje imaju sposobnost proliferacije, migracije, diferencijacije i programirane ćelijske smrti. Ukoliko dođe do narušavanja ravnoteže između ovih procesa, može doći do maligne transformacije zdrave matične ćelije u kancersku matičnu ćeliju. Poznato je da za hemorezistenciju, metastaziranje i recidiviranje tumora odgovornost nosi posebna populaciju tumorskih ćelija koje se nazivaju kancerske matične ćelije. Istraživanja pokazuju da bazocelularni karcinom kože vodi poreklo od matičnih ćelija ispupčenja folikula dlake, infundibuluma dlake i interfolikularnog epidermisa. Bazocelularni karcinom (BCK) je najčešći maligni tumor kože, pa i ako retko metastazira karakteriše ga invazivni rast pri čemu infiltriše okolne strukture i dovodi do ozbiljnih funkcionalnih i estetskih defekata. U literaturi se kao jedan od ključnih faktora odgovornih za recidiviranje navodi neadekvatna širina margine resekcije tumora. Istraživanja su pokazala da je za primarne BCK na koži lica veličine do 20 mm preporučena širina margine 3 mm. Cilj ovog istraživanja bio je identifikacija i karakterizacija subpopulacije ćelija sa osobinama matičnosti izolovanih iz BCK-a i bliske margine od 3 mm, ispitivanjem proliferativnog, klonogenog i migratornog potencijala, analizom ekspresije embrionalnih, mezenhimskih i tumorskih markera, analizom biohemijske strukture ćelija, ispitivanjem sposobnosti diferencijacije u više ćelijskih linija kao i stepena otpornosti ćelija na dejstvo citostatika. U istraživanju je učestvovalo 13 pacijenata sa primarnim bazocelularnim karcinomom na koži lica veličine do 20 mm. Nakon detaljno uzete anamneze i potpisanog informisanog pristanka pristupalo se hirurškoj eksciziji tumorske promene, koja se smatra zlatnim standardom u terapiji BCK-a. Iz svih ekscidiranih uzorka za izolaciju ćelija uzet je deo tumorskog tkiva, tkiva bliske margine (udaljene 3 mm od makroskopske granice tumora) i deo zdrave kože obuhvaćen oblikom resekcije (udaljen od makroskopske granice tumora više od 5 mm), dok je preostali deo tkiva poslat na histopatološku analizu. Za karakterizaciju ćelija u kulturi korišćeni su testovi proliferacije, migracije, formiranja kolonija, sfera i ramanska spektroskopija. Markeri kancerskih matičnih ćelija (KMĆ) analizirani su ,,Real-Time PCR” metodom i protočnom citometrijom...renewal and regeneration and the epidermis harbors a special cell population responsible for the process of self-renewal and regeneration of the skin, so called epidermal stem cells that have the ability to proliferate, migrate, differentiate, and undergo programmed cell death. If imbalance between these processes occurs, malignant transformation of healthy stem cell into the cancerous stem cell may happen. It is also known that a specific population of tumor cells called cancer stem cells is responsible for the hemoresistance, metastasis, and recurrence. Studies have shown that skin basal cell carcinoma is caused by stem cells of hair follicle, hair infundibulum and interfollicular epidermis. Basocellular carcinoma (BCC) is the most common malignant tumor of the skin, but it rarely gives metastases It is characterized by invasive growth, infiltrating surrounding structures and leading to serious functional and aesthetic defects. In the literature, inadequate margins are indicated as one of the key factors responsible for tumor recurrences. Studies have shown that for the primary facial skin BCC of less than 20 mm a margin of 3 mm is recommended. The aim of this study was to identify and characterize the cell subpopulation with stem characteristics whithin BCC and its margins (3 mm close) by testing proliferative, clonogenic and migratory potential, by analyzing the expression of embryonic, mesenchymal and tumor markers, by analizing biochemical structure of cells, by examining the differentiation potential of generated cell lines and by testing the degree of chemo-resistance. The study included 13 patients with primary BCC of face skin of less than 20 mm. Following a detailed anamnesis and a signed informed consent, the surgical excision which is considered a gold standard in BCC therapy, was done. A portion of the tumor tissue, of close margin (3 mm from the macroscopic tumor limit), and of healthy skin included in the resecion (at least 5mm from the macroscopic tumor limit), were obtained from all the patients. The remaining of the tissue was subjected to histopathological analysis. For cell phenotype characterization, tests of proliferation, colony formation, scratch assay, and sphere formation were used..