Diamagnetic response of Aharonov-Bohm rings: Impurity backward scatterings

We report a theoretical calculation on the persistent currents of disordered normal-metal rings. It is shown that the diamagnetic responses of the rings in the vicinity of the zero magnetic field are attributed to multiple backward scatterings off the impurities. We observe the transition from the paramagnetic response to the diamagnetic one as the strength of disorder grows using both the analytic calculation and the numerical exact diagonalization.Comment: final versio

Jamming transition in a highly dense granular system under vertical vibration

The dynamics of the jamming transition in a three-dimensional granular system under vertical vibration is studied using diffusing-wave spectroscopy. When the maximum acceleration of the external vibration is large, the granular system behaves like a fluid, with the dynamic correlation function G(t) relaxing rapidly. As the acceleration of vibration approaches the gravitational acceleration g, the relaxation of G(t) slows down dramatically, and eventually stops. Thus the system undergoes a phase transition and behaves like a solid. Near the transition point, we find that the structural relaxation shows a stretched exponential behavior. This behavior is analogous to the behavior of supercooled liquids close to the glass transition.Comment: 5 pages, 5 figures, accepted by Phys. Rev.

Regulation of Reactive Oxygen Species and the Antioxidant Protein DJ-1 in Mastocytosis

Neoplastic accumulation of mast cells in systemic mastocytosis (SM) associates with activating mutations in the receptor tyrosine kinase KIT. Constitutive activation of tyrosine kinase oncogenes has been linked to imbalances in oxidant/antioxidant mechanisms in other myeloproliferative disorders. However, the impact of KIT mutations on the redox status in SM and the potential therapeutic implications are not well understood. Here, we examined the regulation of reactive oxygen species (ROS) and of the antioxidant protein DJ-1 (PARK-7), which increases with cancer progression and acts to lessen oxidative damage to malignant cells, in relationship with SM severity. ROS levels were increased in both indolent (ISM) and aggressive variants of the disease (ASM). However, while DJ-1 levels were reduced in ISM with lower mast cell burden, they rose in ISM with higher mast cell burden and were significantly elevated in patients with ASM. Studies on mast cell lines revealed that activating KIT mutations induced constant ROS production and consequent DJ-1 oxidation and degradation that could explain the reduced levels of DJ-1 in the ISM population, while IL-6, a cytokine that increases with disease severity, caused a counteracting transcriptional induction of DJ-1 which would protect malignant mast cells from oxidative damage. A mouse model of mastocytosis recapitulated the biphasic changes in DJ-1 and the escalating IL-6, ROS and DJ-1 levels as mast cells accumulate, findings which were reversed with anti-IL-6 receptor blocking antibody. Our findings provide evidence of increased ROS and a biphasic regulation of the antioxidant DJ-1 in variants of SM and implicate IL-6 in DJ-1 induction and expansion of mast cells with KIT mutations. We propose consideration of IL-6 blockade as a potential adjunctive therapy in the treatment of patients with advanced mastocytosis, as it would reduce DJ-1 levels making mutation-positive mast cells vulnerable to oxidative damage

Cluster based routing protocol for mobile nodes in wireless sensor network

Mobility of sensor nodes posed new challenges particularly in energy consumption and demands researchers' attention. Some real applications impose combined environments of fixed and mobile sensor nodes in the same network, while others demand a complete mobile sensors environment. Packet loss that occurs due to mobility of the sensor nodes is one of main challenges in Wireless Sensor Network (WSN) and it comes in parallel with energy consumption. In this paper, we propose adaptive Time Division Multiple Access (TDMA) scheduling and round free cluster head protocol called Cluster Based Routing (CBR) protocol for Mobile Nodes in Wireless Sensor Network (CBR Mobile-WSN). In this protocol the cluster head receive data from not only its member during the TDMA allocated time slot but also other sensor nodes that just enter the cluster when it has free time slots, each cluster head takes turn to be the free cluster head in the network. CBR Mobile-WSN change TDMA scheduling adaptively according to traffic and mobility characteristics. The proposed protocol sends data to cluster heads in an efficient manner based on received signal strength. The performance of proposed CBR Mobile-WSN protocol is evaluated using MATLAB and it has been observed that the proposed protocol reduces the packet loss by 25% compared to LEACH-Mobile protocol

A commentary on the modelling of the causal linkages among nutrient loading, harmful algal blooms, and hypoxia patterns in Lake Erie

In this study, our primary aim is to evaluate the capacity of past and current modelling efforts to depict the causal relationships between major water quality indicators (e.g., chlorophyll a, harmful algal blooms, dissolved oxygen) and nutrient loading in Lake Erie. We first conduct a review of nearly all the modelling projects documented in the pertinent literature, and then evaluate the performance of six of these models applied over the past thirty years. We examine the strengths and weaknesses of the different modelling strategies, their adequacy in representing the processes underlying plankton dynamics, and their ability to reproduce the spatiotemporal variability in hypoxia or harmful algal blooms. Our analysis shows that these models have mainly offered heuristic tools to examine different ecological hypotheses and dictate future data collection efforts. Our study critically discusses the most appropriate next steps to improve the reproduction of the spatiotemporal patterns of major phytoplankton groups, e.g., cyanobacteria, the functional role of dreissenid mussels, and the relative importance of diagenesis processes on the manifestation of hypoxia in Lake Erie. Finally, we advocate the standpoint that a single "correct" strategy does not exist, and therefore we should strive for a synthesis of multiple modelling approaches which can contribute to an integrative view on the functioning of the system. © 2014 International Association for Great Lakes Research. Published by Elsevier B.V. All rights reserved. Introduction Environmental modelling has been an indispensable tool for addressing lake eutrophication. A variety of data-oriented and processbased models have been used to examine the impact of nutrient loads to ecosystem integrity and to set water quality goals. The dataoriented (or empirical) models are mainly steady-state, mass-balance approaches that predict lake total phosphorus (TP) concentrations as a function of lake morphometric/hydraulic characteristics, such as the areal phosphorus loading rate, mean depth, fractional phosphorus retention, and areal hydraulic loading, which are then associated with the chlorophyll a and/or hypolimnetic dissolved oxygen (DO) concentrations An alternative to these empirical strategies has been the development of process-based models which can be used to understand ecological processes, to predict aquatic ecosystem responses to external nutrient loading changes, to evaluate management alternatives, and to support the policy making proces