Performance evaluation of data delivery approaches for wireless sensor networks

AbstractWireless sensor networks are expected to revolutionize our abilities in sensing and controlling the physical environment. Power conservation is a primary research concern for these networks, due to the limited energy resources of the sensor nodes. In this paper we study the data delivery approaches, suitable for hierarchical cluster based wireless sensor networks. A radio energy dissipation model is used to evaluate the energy, needed for both intra-cluster and inter-cluster communication. Based on the results we analyze the performance of various combined data delivery approaches. Additionally we study the impact of the base station location and the number of sensor nodes on the energy dissipation and the network lifetime

An Approach towards Balanced Energy Consumption in Hierarchical Cluster-based Wireless Sensor Networks

In this paper we investigate the mechanisms for organization of the clusters in wireless sensor networks (WSN). After the short introduction to these systems we present the communication architecture and the energy dissipation model, which are used for the hierarchical cluster-based WSN. In the third section of the paper we analyze the current widely used process for organization of the clusters and we outline its main disadvantages. Later we present an approach for balanced consumption of the energy by the sensor motes, and then we propose a modification to this approach. In the next section we present and analyze the results of a series of simulation experiments, which we have conducted with the proposed approach, and then we compare these results with the ones obtained from the simulation experiments, which are conducted with the other presented approaches

Initial Upper Palaeolithic humans in Europe had recent Neanderthal ancestry

Modern humans appeared in Europe by at least 45,000 years ago1–5, but the extent of their interactions with Neanderthals, who disappeared by about 40,000 years ago6, and their relationship to the broader expansion of modern humans outside Africa are poorly understood. Here we present genome-wide data from three individuals dated to between 45,930 and 42,580 years ago from Bacho Kiro Cave, Bulgaria1,2. They are the earliest Late Pleistocene modern humans known to have been recovered in Europe so far, and were found in association with an Initial Upper Palaeolithic artefact assemblage. Unlike two previously studied individuals of similar ages from Romania7 and Siberia8 who did not contribute detectably to later populations, these individuals are more closely related to present-day and ancient populations in East Asia and the Americas than to later west Eurasian populations. This indicates that they belonged to a modern human migration into Europe that was not previously known from the genetic record, and provides evidence that there was at least some continuity between the earliest modern humans in Europe and later people in Eurasia. Moreover, we find that all three individuals had Neanderthal ancestors a few generations back in their family history, confirming that the first European modern humans mixed with Neanderthals and suggesting that such mixing could have been common

Long-range Angular Correlations On The Near And Away Side In P-pb Collisions At √snn=5.02 Tev

7191/Mar294

Vicinal disulfide turns

The formation of a disulfide bond between adjacent cysteine residues is accompanied by the formation of a tight turn of the protein backbone. In nearly 90% of the structures analyzed a type VIII turn was found. The peptide bond between the two cysteines is in a distorted trans conformation, the omega torsion angle ranges from 159 to -133degrees, with an average value of 171degrees. The constrained nature of the vicinal disulfide turn and the pronounced difference observed between the oxidized and reduced states, suggests that vicinal disulfides may be employed as a 'redox-activated' conformational switch

On fractional systems with Riemann-Liouville derivatives and distributed delays – Choice of initial conditions, existence and uniqueness of the solutions

A comparative analysis among the possible types of initial conditions including (or not) derivatives in the Riemann-Liouville sense for incommensurate fractional differential systems with distributed delays is proposed. The provided analysis is essentially based on the possibility to attribute physical meaning to the initial conditions expressed in terms of Riemann-Liouville fractional derivatives. This allows the values of the initial functions for the mentioned initial conditions to be obtained by appropriate measurements or observations. In addition, an initial problem with non-continuous initial conditions partially expressed in terms of Riemann-Liouville fractional derivatives is considered and existence and uniqueness of a (1 − α)-continuous solution of this initial problem is proved