bluuebunny/crossref_metadata_2025 huggingface dataset:
Interaction, mobility, and phosphorylation of human orthologues of WD repeat-containing components of the yeast SSU processome t-UTP sub-complex
Authors: Sato Manae , Araki Nanase , Kumeta Masahiro , Takeyasu Kunio , Taguchi Yusuke , Asai Takahiro , Furukawa Kazuhiro , Horigome Tsuneyoshi
Published: July 2013

We previously proposed a dynamic scaffold model for inner nuclear structure formation. In this model, structures in inter-chromatin regions are maintained through dynamic interaction of protein complex modules, and WD repeat- and disordered region-rich proteins and others act as scaffolds for these protein complexes. In this study, three WD-repeat proteins, i.e., CIRH1A, UTP15, and WDR43, were found in the nuclear matrix fraction and speculated to be present in the human t-UTP sub-complex of SSU processomes. The results obtained as to their subnuclear localization, binding with each other, mobilities, and phosphorylation were: (i) the majority of these proteins fused with GFP are localized to the fibrillar center region in nucleoli. (ii) these 3 proteins bind directly with each other in vitro. (iii) the movement of these proteins is very slow in living cells and independent of rDNA transcription. (iv) His-CIRH1A is phosphorylated at Thr131 by a mitotic Xenopus egg extract, and binding with GST-UTP15 and GST-WDR43 is suppressed. These findings and others suggest that these 3 WD proteins found in the matrix fraction bind directly with each other, bind tightly to fibrillar center regions, and comprise a part of the nucleolar structure. These results are also consistent with our dynamic scaffold model.
GENERATION OF SCALE INVARIANT DENSITY PERTURBATIONS IN A CONFORMALLY INVARIANT INERT HIGGS DOUBLET MODEL
Authors: DAS MOUMITA , MOHANTY SUBHENDRA
Published: July 2013

If a Higgs field is conformally coupled to gravity, then it can give rise to the scale invariant density perturbations. We make use of this result in a realistic inert Higgs doublet model, where we have a pair of Higgs doublets conformally coupled to the gravity in the early universe. The perturbation of the inert Higgs is shown to be the scale invariant. This gives rise to the density perturbation observed through CMB by its couplings to the standard model Higgs and the subsequent decay. Loop corrections of this conformally coupled system gives rise to electroweak symmetry breaking. We constrain the couplings of the scalar potential by comparing with the amplitude and spectrum of CMB anisotropy measured by WMAP and this model leads to a prediction for the masses of the lightest Higgs and the other scalars.
ELECTRONIC STRUCTURE AND ELECTRON CHARGE DENSITY IN THE INTERATOMIC BONDS OF BiSBr and BiSeBr CRYSTALS
Authors: AUDZIJONIS A. , SEREIKA R.
Published: July 2013

Electronic structure and electronic charge density in the interatomic bonds are investigated with ab initio calculations based on the density-functional theory. The full potential linearized augmented plane-wave method was used with the generalized gradient approximation. Considering the partial density of states the electron charge density distribution in the Bi , S , Se and Br atomic bonds is caused by Bi-6p , S-3p , Se-4p , Br-4p orbital hybridization. Electronic charge distribution of one BiSBr and BiSeBr molecule range suggest that the Bi – S , Bi – Se and Bi – Br bonds are covalent–ionic type. Bi – S and Bi – Se bonds are strong covalent with a not great ionicity factor ([Formula: see text], Bi – S ; [Formula: see text], Bi – Se ). Bi – Br bonds are covalent type with a larger ionicity factor ([Formula: see text], Bi – Br ).
PREPARATION AND CHARACTERIZATION OF AMINO-MODIFIED Fe3O4 MAGNETIC NANOCOMPOSITE PARTICLES BY ONE-STEP GLYCOTHERMAL METHOD
Authors: ZHANG YUHONG , YAN BIAO , SHI TAIGANG
Published: July 2013

Amino-modified Fe 3 O 4 magnetic nanocomposite particles were prepared by one-step glycothermal method. The shape and morphology of Fe 3 O 4 particles change when a small amount of water is added as a co-solvent in the glycothermal method. The morphology and structure of the sample were characterized and measured by transmission electron microscopy (TEM), X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. TEM images show that the morphology of the samples is from irregular polyhedron to spherical particles. Average diameter of particles is approximately 70/40/10 nm and more evenly distributed. XRD results show that the samples are cubic spinel structure. FTIR results show that a chemical bonds combination exists between the amino and iron oxide, nano-iron oxide are modified by the amino.
PREPARATION OF ULTRAFINE W–Cu COMPOSITE POWDER USING ULTRASONIC-ASSISTED ELECTROLESS PLATING
Authors: HUANG LIMEI , LUO LAIMA , DING XIAOYU , ZAN XIANG , HONG YU , CHENG JIGUI , WU YUCHENG , LUO GUANGNAN , ZHU LIU
Published: July 2013

W – Cu ultrafine/nanocomposite powders have high sintering activity, so ultrafine/nanotechnology of W – Cu composite powders is one of the main methods to obtain fully dense, high-performance W – Cu composite materials. Cu -coated ultrafine W composite powders were synthesized by ultrasonic-assisted electroless plating process with non-noble metal activation pretreatment at room temperature in this paper. The growth mechanism of Cu layers and surface morphologies and composition of initial ultrafine W powders, pretreated W powders and Cu -coated W powders were analyzed by field emission scanning electron microscopy (FE-SEM), and energy dispersion spectrometry (EDS). The results show that the uniformly Cu coated W composite powder is successfully synthesized without conventional sensitization and activation steps by ultrasonic-assisted electroless plating at room temperature. The Cu layers on the ultrafine W powders had cell structure with dense, uniform distribution. The growth mechanism of Cu layers appears as follows: the surfaces of pretreated W powders appear linear-like and lamellar-like surface defects which act as activated sites. The reactants in the plating solution were adsorbed on catalytic activity surfaces of powders and happened oxidation–reduction reaction. The growth and aggregation mechanisms of Cu particles after nucleation are stripy Cu -cells grew up, bend, bifurcated, and aggregated, then wounding into a cellular structure, like "wrapping wool clusters" in the life. Finally, Cu cells grow up and merge into a layer.
THE PREPARATION AND CHARACTERIZATION OF GRAPHENE BY LIQUID OXIDATION-REDUCTION METHOD
Authors: ZHANG YUHONG , YAN BIAO , LU WEI
Published: July 2013

Graphite oxide was prepared by Hummers method, then it was obtained by ultrasound. Finally, graphene was prepared by using hydrazine hydrate as reducing agent. We can get the influences of oxidation time on the graphene structure by different reacting times. Ultrasonication can reduce the aggregation of graphene efficiently. The morphology and size of graphene were characterized by SEM, TEM, XRD and FTIR. Through this method, we can get high quality graphene which has smooth surface and fewer defects. The longer the oxidation time, the more easier it is to peel and insert functional groups.
MAGNETIC ANISOTROPY OF CoFeB AMORPHOUS NANOTUBES PREPARED BY ELECTROLESS PLATING IN MAGNETIC FIELD
Authors: LIU Z. , LI W. L. , FEI W. D.
Published: July 2013

CoFeB nanotubes were fabricated by electroless plating in magnetic field using anodized aluminum oxide template, and the structural and magnetic properties of CoFeB nanotubes were investigated. It is found that some nano-scale particles form on the wall of nanotubes. Both coercivity ratio and squareness ratio of out-of-plane to in-plane are significantly changed by the applied magnetic field during electroless plating, which indicates that directional ordering in amorphous CoFeB nanotubes are achieved during electroless plating under magnetic field. The results show that the applied field impacts the magnetic anisotropy of amorphous nanotubes. The anisotropy is stronger with the magnitude of applied field increasing.
ELECTROMAGNETIC MICROWAVE PROPERTIES OF Fe82B17Cu1 BALL MILLED ALLOY
Authors: TIAN N. , FAN X. D. , WANG J. W. , YOU C. Y. , LU Z. X. , GE L. L.
Published: July 2013

High saturation magnetization and magnetic anisotropy are helpful for getting a high frequency electromagnetic microwave absorption performance. The α- Fe possesses a high saturation magnetization. Fe - B phases exhibit a relatively higher magnetic anisotropy and higher resistivity than α- Fe simultaneously. In this work, we made nanocrystalline powders of Fe 82 B 17 Cu 1, mainly consisting of α- Fe and Fe 2 B phases, by ball milling and post-annealing. Electromagnetic microwave characterization shows that Fe 82 B 17 Cu 1 powders possess a relative high permeability and considerable permittivity. Due to a good electromagnetic impedance matching, a good electromagnetic microwave absorption property (RL < -35 dB) has been achieved at 3.6 GHz. The experimental frequency and the matching thickness are coincident with the quarter wavelength matching condition.
STUDY ON HIGH STRAIN RATE COMPRESSION SUPERPLASTICITY OF AS-EXTRUDED AZ31 MAGNESIUM ALLOY
Authors: LIN FEI , LI JIE , ZHAO HONGWEI , SUN LULU , CHEN ZHITONG , MENG QINGSEN
Published: July 2013

The grain size of as-extruded AZ31 magnesium alloy was refined by isothermal annealing pretreatment through orthogonal experiment. By using the Gleeble-3800 thermal simulator, the compression superplasticity of as-extruded AZ31 magnesium alloy was studied. The high strain rate superplastic compression was realized. The process parameters of the superplastic compression were established and the mechanism of the superplastic deformation was analyzed. The effects of deformation temperature and strain rate on the superplastic flow were investigated. The results indicated that at 250°C–300°C and strain rate at 1×10-2 s -1, the true strain values were all more than 2.03. As the temperature was 300°C and the strain rate was 1×10-2 s -1–1×10 s -1, the true strain values were all more than 2.18. The results showed that the as-extruded AZ31 magnesium alloy being refined presented good compression superplasticity. The main mechanism for the superplastic compressive deformation of the as-extruded AZ31 magnesium alloy was grain-boundary sliding, meanwhile, dynamic recrystallization also played a harmonious role during the superplastic deformation.
MICROSTRUCTURE AND PROPERTIES OF SiC PARTICLES REINFORCED COPPER BASED ALLOY COMPOSITE
Authors: HONG YU , CHEN XIAOLI , WANG WENFANG , WU YUCHENG
Published: July 2013

Copper-matrix composites reinforced with SiC particles are prepared by mechanical alloying. The microstructure characteristics, relative density, hardness, tensile strength, electrical conductivity, thermal conductivity and wear properties of the composites are investigated in this paper. The results indicate that the relative density, macro-hardness and mechanical properties of composites are improved by modifying the surface of SiC particles with Cu and Ni . The electrical conductivity and thermal conductivity of composites, however, are not obviously improved. For a given volume fraction of SiC , the Cu / SiC ( Ni ) has higher mechanical properties than Cu / SiC ( Cu ). The wear resistance of the composites are improved by the addition of SiC . The composites with optimized interface have lower wear rate.
CORROSION OF AMORPHOUS AND NANOCRYSTALLINE Fe-BASED ALLOYS IN NaCl AND H2SO4 SOLUTIONS
Authors: LI XIANG , LU WEI , WANG YUXIN , YAN BIAO , PAN DENG
Published: July 2013

Corrosion resistance of nanocrystalline Fe 73.5 Si 13.5 B 9 Nb 3 Cu 1 alloy was investigated and compared to its amorphous counterpart. Low-temperature crystallization occurred during the annealing of amorphous tapes was used to obtain a nanocrystalline structure. The influence of annealing condition on the structure and corrosion resistance of the alloy in NaCl and H 2 SO 4 solutions was investigated. Based on the testing results, it was found that nanocrystalline tapes have higher corrosion resistance than amorphous counterpart and H 2 SO 4 can promote the occurrence of corrosion compared with NaCl .
STUDY ON THE ADSORPTION OF SULFATE IONS ONTO CROSS-LINKED CHITOSAN
Authors: XUE JUANQIN , GUO YINGJUAN , BI QIANG , MAO WEIBO , LI JINGXIAN
Published: July 2013

With chitosan as the raw material, a new type of resin material is synthesized through cross-linking with formaldehyde and benzaldehyde, and it was used as an adsorbent to adsorb sulfate ion from aqueous solution. The effect of different conditions and the kinetics of the adsorption were investigated. Under the conditions of 0.2 g of adsorbent dosage, 153.3 mg/L of sodium sulfate solution, 40°C of the temperature, 120 min of the equilibrium time and pH of 2.0, the adsorption efficiency (AE) and the adsorption capacity (AC) can both be obtained the optimal values. It shows that the applicability of the second-order model fit the experimental data well from the study of adsorption kinetics.
PREPARATION OF MODIFIED CHITOSAN BY GRAFT POLYMERIZATION AND ITS ADSORPTION OF Cd2+ AND Co2+ FROM BINARY SOLUTION
Authors: BI QIANG , XUE JUANQIN , GUO YINGJUAN , MAO WEIBO , WANG YUJIE
Published: July 2013

The grafting copolymerization of chitosan with acrylamide and acrylonitrile was studied which initiated by NaHSO 3– K 2 S 2 O 8. And the chitosan–acrylamide–acrylonitrile ternary graft copolymer was synthesized in N 2 atmosphere. Under the optimal experimental conditions, the average graft ratio and the graft efficiency could up to 852.46% and 85.26%, respectively. The adsorption selectivity and influences to the adsorption by factors like adsorption time, adsorption temperature, initial concentration of metal ion and initial pH of the solution were studied. The results showed that: the adsorption selectivity was obtained of the ternary graft copolymer to Cd 2+; under the same experimental conditions, the maximum difference of adsorption rate between Cd 2+ and Co 2+ by polymer would be 31.07%.
CALCULATIONS OF SELF-DIFFUSION PROCESS AND COEFFICIENT IN ORDERED B2 AlCo
Authors: NONG ZHI-SHENG , ZHU JING-CHUAN , CAO YONG , YANG XIA-WEI , LAI ZHONG-HONG , LIU YONG
Published: July 2013

The self-diffusion process in B2 type intermetallic compound AlCo has been investigated by the first-principles calculations within the frame work of density functional theory (DFT). The obtained mono-vacancy formation, migration and activation energies for four self-diffusion mechanisms, the next-nearest-neighbor (NNN) jump, [110] six-jump cycle (6JC), straight [100] 6JC and bent [100] 6JC diffusion show that the NNN jump mechanism of Co vacancy requires the lowest activation energy (Q = 6.835 eV ) in these diffusion mechanisms, which indicates that it is the main way of self-diffusion in AlCo . The electronic structure including the electron density difference on (-1 1 0) plane as well as atomic Mulliken populations were calculated, and the change of bonding behavior during the [110] 6JC process was discussed in detail. Finally, the self-diffusion coefficients of NNN jump and 6JC mechanisms for AlCo were also studied via the first-principles calculations and semi-empirical predictions, which indicates that the self-diffusion coefficients for NNN jump of Co vacancy show the highest value than the others.
MULTI-TONE MEASUREMENT SYSTEM WITH THE STATE-OF-THE-ART ACTIVE IF AND RF LOAD-PULL CAPABILITY
Authors: CHAUDHARY MUHAMMAD AKMAL , LEES JONATHAN , BENEDIKT JOHANNES , TASKER PAUL
Published: July 2013

This paper reports a refined multi-tone waveform measurement system for the robust characterization and optimization of nonlinear microwave devices when driven by broadband multi-tone stimuli. This enhanced system has the ability to present specific, constant broadband impedances, not only at baseband (IF) frequencies, but also at RF frequencies, particularly, around the carrier and significant harmonics. This functionality is key in studying the effects of out-of-band impedance termination on both short and long-term electrical memory effects. Achieving such comprehensive impedance control across wide modulation bandwidths is also critical in allowing the "emulation" of emerging power amplifier modes and architectures, and the subsequent waveform characterization of devices operating in these complex and often dynamic impedance environments. Initially, the baseband load-pull capabilities of the enhanced measurement system are experimentally demonstrated through the measurement of adjacent channel power (ACP) behavior of a class AB biased 10 W GaN HEMT, in response to a varying baseband load. Complete baseband and RF impedance control is then demonstrated through the emulation and analysis of a modulated Class-J impedance environment, which interestingly highlights the presence of separate optimum baseband impedance conditions necessary for the suppression of individual IM products.
A DYNAMICAL STATE FEEDBACK CHAOTIFICATION METHOD WITH APPLICATION ON LIQUID MIXING
Authors: ŞAHİN SAVAŞ , GÜZELİŞ CÜNEYT
Published: July 2013

This paper introduces chaotic reference model-based dynamical state feedback chaotification method which can be applied to any input-state linearizable (nonlinear) system including linear controllable ones as special cases. In the developed method, any chaotic system of arbitrary dimension can be used as the reference model with no need to transform it into a special form, so providing the advantage of exploiting the vast amount of information on chaotic systems and their implementations available in the literature. To demonstrate the potential effective applications of the method, a permanent magnet dc motor is chaotified by the proposed dynamical state feedback as matching the closed loop dynamics to the well-known Chua's chaotic circuit. Then, an impeller mounted on the chaotified dc motor is used for mixing a corn syrup added acid–base mixture. It is observed in a nonintrusive way that mixing actuated by the chaotified dc motor is more efficient than constant and also periodical motor speed cases for the consideration of neutralization time and power consumption together.
FORMIC ACID DEHYDROGENATION ON SURFACES — A REVIEW OF COMPUTATIONAL ASPECT
Authors: LUO QIQUAN , BELLER MATTHIAS , JIAO HAIJUN
Published: July 2013

In this review, we have mainly shown the recent computational studies on formic acid adsorption and selective dissociation to produce hydrogen ( HCOOH → CO 2 + H 2) on several metal ( Pt , Pd , Ni , Cu , Rh and Au ) and metal oxide ( TiO 2, MgO , ZnO and NiO ) surfaces, and both thermal decomposition and electro-catalytic oxidation have been discussed. The decomposition mechanisms of formic acid have been studied by using different computational models and methods, not only interesting and exciting but also different and controversial results have been reported. It is noted that the model systems used in these studies are too simple and idealized, and they cannot represent the real catalysts or the catalytic systems, and more sophisticated computational methodologies and real model systems under the consideration of the working conditions are therefore needed.
HAND GRASP FUNCTION ANALYSIS BASED ON VF SET
Authors: ZHAN QIANG , LIU XIANCAN
Published: July 2013

This paper presents a method based on virtual finger (VF) set to analyze the grasp function of bionic hand. In order to exactly represent different function units of human hand or bionic hand a more detailed classification of VF is proposed to divide VF into three types: VFFE, VFAA and VFPalm, of which a VF set describing hand grasp can be composed. The VF set cannot only describe the degree of freedom (DOF) distribution of human hand or bionic hand but also indicate which fingers take part in grasp and what motion types the fingers are. The VF sets of eight classic bionic hands and five basic human hand grasp postures are provided. The inclusion relationship between the VF set of a bionic hand and those of the basic human hand grasp postures is used to analyze the grasp function of a bionic hand. As examples the grasp functions of several classic bionic hands, such as i-LIMB Hand, HIT/DLR Hand, etc. are analyzed.
TOWARD AUTOMATED GENERATION OF CHINESE CLASSIC POETRY
Authors: LIN HONG
Published: July 2013

The forms of Chinese classic poetry have been developed through thousands of years of history and are still current in today's poetry society. A re-classification of the rhyming words, however, is necessary to keep the classic poetry up to date in the new settings of modern Chinese language. To ease the transition process, computing technology is used to help the readers as well as poetry writers to check the compliance of poems in accordance with the forms and to compose poems without the effort to learn the old grouping of rhyming words. A piece of software has been developed in a faculty/student research project at the University of Houston-Downtown to verify this idea. This software, called Chinese classic poetry wizard, provides the functionality of checking metrical forms and rhyming schemes. It also allows users to edit rhyme dictionaries and metrical forms. The new rhyming scheme proposed in this paper should rationalize the composition rules of classic Chinese poetry in the modern society; and the poem composition wizard will provide a handy tool for poem composition. This work will help revive Chinese classic poetry in modern society and, in a sequel, contribute to the current campaign of advocating Chinese traditional teachings.
ON THE DUAL NOTION OF PRIME RADICALS OF SUBMODULES
Authors: Ansari-Toroghy H. , Farshadifar F.
Published: July 2013

Let R be a commutative ring and M be an R-module. In this paper, we will study the dual notion of prime radicals (that is, second socles) of submodules of M and obtain some related results.
TEMPORAL INVESTMENT IN CLIMATE CHANGE ADAPTATION AND MITIGATION
Authors: WANG WEIWEI , McCARL BRUCE A.
Published: July 2013

Increasingly there appears to be recognition of the need to simultaneously implement adaptation and mitigation. However, the optimal combination of adaptation and mitigation is an open question. The literature on this is rather small, and is inconsistent in conclusions. Here we explore the temporal optimal investment mix between adaptation and mitigation and their relative contributions to damage reduction. We do this using a conceptual framework that integrates mitigation and adaptation considering one time flow and persistent stock adaptation. We also consider unadaptable damages and investment competition. Results suggest that stock and flow adaptation are dominant damage reduction means in the first 120 years while mitigation dominates from thereon. We also find that the adaptation/mitigation mix changes markedly toward mitigation when climate change damages per unit atmospheric CO2concentration rises.
Adaptive
k
-coverage contour evaluation and deployment in wireless sensor networks
Authors: Sheu Jang-Ping , Chang Guey-Yun , Wu Shan-Hung , Chen Yen-Ting
Published: July 2013

The problem of coverage is a fundamental issue in wireless sensor networks. In this article, we consider two subproblems:
k
-coverage contour evaluation and
k
-coverage rate deployment. The former aims to evaluate, up to
k
, the coverage level of any location inside a monitored area, while the latter aims to determine the locations of a given set of sensors to guarantee the maximum increment of
k
-coverage rate when they are deployed into the area. For the
k
-coverage contour evaluation problem, a nonuniform-grid-based approach is proposed. We prove that the computation cost of our approach is at most the square root of existing solutions. Based on our
k
-coverage contour evaluation scheme, a greedy
k
-coverage rate deployment scheme (
k
-CRD) is proposed, which is shown to be an order faster than existing studies for
k
-coverage rate deployment. The
k
-CRD can incorporate two different heuristics to further reduce its running time. Simulation results show that
k
-CRD with these heuristics can be significantly more time efficient without causing much degradation in the coverage rate of final deployment.
DutyCon
Authors: Wang Xiaodong , Wang Xiaorui , Liu Liu , Xing Guoliang
Published: July 2013

It is well known that periodically putting nodes into sleep can effectively save energy in wireless sensor networks at the cost of increased communication delays. However, most existing work mainly focuses on the static sleep scheduling, which cannot guarantee the desired delay when the network conditions change dynamically. In many applications with user-specified end-to-end delay requirements, the duty cycle of every node should be tuned individually at runtime based on the network conditions to achieve the desired end-to-end delay guarantees and energy efficiency. In this article, we propose DutyCon, a control theory-based dynamic duty-cycle control approach. DutyCon decomposes the end-to-end delay guarantee problem into a set of single-hop delay guarantee problems along each data flow in the network. We then formulate the single-hop delay guarantee problem as a dynamic feedback control problem and design the controller rigorously, based on feedback control theory, for analytic assurance of control accuracy and system stability. DutyCon also features a queuing delay adaptation scheme that adapts the duty cycle of each node to unpredictable incoming packet rates, as well as a novel energy-balancing approach that extends the network lifetime by dynamically adjusting the delay requirement allocated to each hop. Our empirical results on a hardware testbed demonstrate that DutyCon can effectively achieve the desired trade-off between end-to-end delay and energy conservation. Extensive simulation results also show that DutyCon outperforms two baseline sleep scheduling protocols by having more energy savings while meeting the end-to-end delay requirements.
Energy efficiency in wireless sensor networks
Authors: Voulkidis Artemis C. , Anastasopoulos Markos P. , Cottis Panayotis G.
Published: July 2013

A coalitional game theoretic scheme is proposed that aims at maximizing wireless sensor network lifetime under specified QoS. Employing a small number of nodes of increased computing power and lifetime called
representatives
, an adaptive clustering scheme is proposed where neighboring nodes form coalitions in order to increase energy efficiency at the cost of controllable data-accuracy reduction. The coalition formation is globally optimized by the representatives. The spatial correlation of the sensed phenomenon measurements is exploited to formulate a cooperation scheme that reduces drastically the number of node transmissions. The specifications regarding the accuracy of the collected data determine the extent of coalition formation. The efficiency and stability of the proposed coalitional scheme are studied through simulations.
Cell-based snapshot and continuous data collection in wireless sensor networks
Authors: Ji Shouling , He Jing (Selena) , Uluagac A. Selcuk , Beyah Raheem , Li Yingshu
Published: July 2013

Data collection is a common operation of wireless sensor networks (WSNs). The performance of data collection can be measured by its achievable network capacity. However, most existing works focus on the network capacity of unicast, multicast or/and broadcast. In this article, we study the snapshot/continuous data collection (SDC/CDC) problem under the physical interference model for randomly deployed dense WSNs. For SDC, we propose a
Cell-Based Path Scheduling
(CBPS) algorithm based on network partitioning. Theoretical analysis shows that its achievable network capacity is order-optimal. For CDC, a novel
Segment-Based Pipeline Scheduling
(SBPS) algorithm is proposed which combines the pipeline technique and the compressive data gathering technique. Theoretical analysis shows that SBPS significantly speeds up the CDC process and achieves a high network capacity.
Exploiting Redundancies and Deferred Writes to Conserve Energy in Erasure-Coded Storage Clusters
Authors: Huang Jianzhong , Zhang Fenghao , Qin Xiao , Xie Changsheng
Published: July 2013

We present a power-efficient scheme for erasure-coded storage clusters---ECS2---which aims to offer high energy efficiency with marginal reliability degradation. ECS2utilizes data redundancies and deferred writes to conserve energy. In ECS2parity blocks are buffered exclusively in active data nodes whereas parity nodes are placed into low-power mode. (k+r, k) RS-coded ECS2can achieve ⌈(r+ 1)/2⌉-fault tolerance forkactive data nodes andr-fault tolerance for allk+rnodes. ECS2employs the following three optimizing approaches to improve the energy efficiency of storage clusters. (1) An adaptive threshold policy takes system configurations and I/O workloads into account to maximize standby time periods; (2) a selective activation policy minimizes the number of power-transitions in storage nodes; and (3) a region-based buffer policy speeds up the synchronization process by migrating parity blocks in a batch method. After implementing an ECS2-based prototype in a Linux cluster, we evaluated its energy efficiency and performance using four different types of I/O workloads. The experimental results indicate that compared to energy-oblivious erasure-coded storage, ECS2can save the energy used by storage clusters up to 29.8% and 28.0% in read-intensive and write-dominated workloads when k = 6 and r = 3, respectively. The results also show that ECS2accomplishes high power efficiency in both normal and failed cases without noticeably affecting the I/O performance of storage clusters.
On bottleneck analysis in stochastic stream processing
Authors: Nadakuditi Raj Rao , Markov Igor L.
Published: July 2013

Past improvements in clock frequencies have traditionally been obtained through technology scaling, but most recent technology nodes do not offer such benefits. Instead,
parallelism
has emerged as the key driver of chip-performance growth. Unfortunately, efficient simultaneous use of on-chip resources is hampered by sequential dependencies, as illustrated by Amdahl's law. Quantifying achievable parallelism in terms of provable mathematical results can help prevent futile programming efforts and guide innovation in computer architecture toward the most significant challenges. To complement Amdahl's law, we focus on stream processing and quantify performance losses due to stochastic runtimes. Using spectral theory of random matrices, we derive new analytical results and validate them by numerical simulations. These results allow us to explore unique benefits of stochasticity and show how and when they outweigh the costs for software streams.
Thread-based multi-engine model checking for multicore platforms
Authors: Cabodi Gianpiero , Nocco Sergio , Quer Stefano
Published: July 2013

This article describes a multithreaded, portfolio-based approach to model checking, where multiple cores are exploited as the underlying computing framework to support concurrent execution of cooperative engines.

We introduce a portfolio-based approach to model checking. Our portfolio is first driven by an approximate runtime predictor that provides a heuristic approximation to a
perfect oracle
and suggests which engines are more suitable for each verification instance. Scalability and robustness of the overall model-checking effort highly rely on a concurrent, multithreaded model of execution.

Following similar approaches in related application fields, we dovetail data partitioning, focused on proving several properties in parallel, and engine partitioning, based on concurrent runs of different model-checking engines competing for completion of the same problem.

We investigate concurrency not only to effectively exploit several available engines, which operate independently, but also to show that a cooperative effort is possible. In this case, we adopt a straightforward, light-weight, model of inter-engine communication and data sharing.

We provide a detailed description of the ideas, algorithms, and experimental results obtained on the benchmarks from the Hardware Model Checking Competition suites (HWMCC'10 and HWMCC'11).
Routability optimization for crossbar-switch structured ASIC design
Authors: Tsai Mei-Hsiang , Hsu Po-Yang , Li Hung-Yi , Hung Yi-Huang , Liu Yi-Yu
Published: July 2013

In the routing architecture of a structured application-specific integrated circuit (ASIC), the crossbar is one of the most area-efficient switch blocks. Nevertheless, a dangling wire occurs when there is a routing bend in a crossbar switch. Dangling wires incur longer wire lengths as well as a higher interconnection capacitance. In this article, we tackle dangling wire issues for structured ASIC routability optimization. We first propose a compact graph model for crossbar-switch routing. With our graph model, switch connectivity relations can be removed to keep the 2D structured ASIC routing graph efficient and to speed up the runtime of our routing algorithm. Furthermore, we propose a heuristic dangling-wire-avoidance routing framework containing deferred pin assignment, Steiner point reassignment, and anchor pair insertion in order to minimize dangling wires and channel width. Finally, in order to take routing bends and channel width into account simultaneously, we propose concurrent and sequential integer linear programming (ILP) formulations and ILP variable/constraint degeneration techniques. The experimental results demonstrate that our proposed heuristic routing framework reduces dangling wires by 19%, channel width by 38%, and wire length by 13% to VPR using the crossbar switch (VPR-C). In addition, our sequential ILP router reduces dangling wires by 38%, channel width by 40%, and wire length by 15% compared to VPR-C. Thus, the runtime efficiency of our sequential ILP router is attractive for crossbar-switch structured ASIC routing.
Agglomerative-based flip-flop merging and relocation for signal wirelength and clock tree optimization
Authors: Liu Sean Shih-Ying , Lo Wan-Ting , Lee Chieh-Jui , Chen Hung-Ming
Published: July 2013

In this article, we propose a flip-flop merging algorithm based on agglomerative clustering. Compared to previous state-of-the-art on flip-flop merging, our proposed algorithm outperforms that of Chang et al. [2010] and Wang et al. [2011] in all aspects, including number of flip-flop reductions, increase in signal wirelength, displacement of flip-flops, and execution time. Our proposed algorithm also has minimal disruption to original placement. In comparison with Jiang et al. [2011], Wang et al. [2011], and Chang et al. [2010], our proposed algorithm has the least displacement when relocating merged flip-flops. While previous works on flip-flop merging focus on the number of flip-flop reduction, we further evaluate the power consumption of clock tree after flip-flop merging. To further minimize clock tree wirelength, we propose a framework that determines a preferable location for relocated merged flip-flops for clock tree synthesis (CTS). Experimental results show that our CTS-driven flip-flop merging can reduce clock tree wirelength by an average of 7.82% with minimum clock network power consumption compared to all of the previous works.
Overt censorship
Authors: Richet Jean-Loup
Published: July 2013

Censorship of information often has the opposite effect by drawing attention to the censored material.
Resolvers Revealed
Authors: Shue Craig A. , Kalafut Andrew J.
Published: July 2013

The Domain Name System (DNS) allows clients to use resolvers, sometimes called caches, to query a set of authoritative servers to translate host names into IP addresses. Prior work has proposed using the interaction between these DNS resolvers and the authoritative servers as an access control mechanism. However, while prior work has examined the DNS from many angles, the resolver component has received little scrutiny. Essential factors for using a resolver in an access control system, such as whether a resolver is part of an ISP’s infrastructure or running on an end-user’s system, have not been examined. In this study, we examine DNS resolver behavior and usage, from query patterns and reactions to nonstandard responses to passive association techniques to pair resolvers with their client hosts. In doing so, we discover evidence of security protocol support, misconfigured resolvers, techniques to fingerprint resolvers, and features for detecting automated clients. These measurements can influence the implementation and design of these resolvers and DNS-based access control systems.
Regenerating codes
Authors: Jiekak Steve , Kermarrec Anne-Marie , Le Scouarnec Nicolas , Straub Gilles , Van Kempen Alexandre
Published: July 2013

The explosion of the amount of data stored in cloud systems calls for more efficient paradigms for redundancy. While replication is widely used to ensure data availability, erasure correcting codes provide a much better trade-off between storage and availability. Regenerating codes are good candidates for they also offer low repair costs in term of network bandwidth. While they have been proven optimal, they are difficult to understand and parameterize. In this paper we provide an analysis of regenerating codes for practitioners to grasp the various trade-offs. More specifically we make two contributions: (i) we study the impact of the parameters by conducting an analysis at the level of the system, rather than at the level of a single device; (ii) we compare the computational costs of various implementations of codes and highlight the most efficient ones. Our goal is to provide system designers with concrete information to help them choose the best parameters and design for regenerating codes.
Banking on decoupling
Authors: Taifi Moussa
Published: July 2013

Cloud providers are auctioning their excess capacity using dynamically priced virtual instances. These spot instances provide significant savings compared to on-demand or fixed price instances. The users willing to use these resources are asked to provide a maximum bid price per hour, and the cloud provider runs the instances as long as the market price is below the user's bid price. By using such resources, the users are exposed explicitly to failures, and need to adapt their applications to provide some level of fault tolerance. In this paper, we expose the effect of bidding in the case of virtual HPC clusters composed of spot instances. We describe the interesting effect of uniform versus non-uniform bidding in terms of both the failure rate and the failure model. We propose an initial attempt to deal with the problem of predicting the runtime of a parallel application under various bidding strategies and various system parameters. We describe the relationship between bidding strategies and programming models, and we build a preliminary optimization model that uses real price traces from Amazon Web Services as inputs, as well as instrumented values related to the processing and network capacities of cluster instances on the EC2 services. Our results show preliminary insights into the relationship between non-uniform bidding and application scaling strategies.
Multi-core systems modeling for formal verification of parallel algorithms
Authors: Desnoyers Mathieu , McKenney Paul E. , Dagenais Michel R.
Published: July 2013

Modeling parallel algorithms at the architecture level enables exploring side-effects of the weakly ordered nature of modern processors. Formal verification of such models with model-checking can ensure that algorithm guarantees will hold even in the presence of the most aggressive compiler and processor optimizations.

This paper proposes a virtual architecture to model the effects of such optimizations. It first presents the OoOmem framework to model out-of-order memory accesses. It then presents the OoOisched framework to model the effects of out-of-order instruction scheduling.

These two frameworks are explained and tested using weaklyordered memory interaction scenarios known to be affected by weak ordering. Then, modeling of user-level RCU (Read- Copy Update) synchronization algorithms is presented. It uses the virtual architecture proposed to verify that the RCU guarantees are indeed respected.
Regulation of large-conductance Ca2+-activated K+ channels by WNK4 kinase
Authors: Wang Zhijian , Subramanya Arohan R. , Satlin Lisa M. , Pastor-Soler Núria M. , Carattino Marcelo D. , Kleyman Thomas R.
Published: July 2013

Large-conductance, Ca2+-activated K+ channels, commonly referred to as BK channels, have a major role in flow-induced K+ secretion in the distal nephron. With-no-lysine kinase 4 (WNK4) is a serine-threonine kinase expressed in the distal nephron that inhibits ROMK activity and renal K+ secretion. WNK4 mutations have been described in individuals with familial hyperkalemic hypertension (FHHt), a Mendelian disorder characterized by low-renin hypertension and hyperkalemia. As BK channels also have an important role in renal K+ secretion, we examined whether they are regulated by WNK4 in a manner similar to ROMK. BK channel activity was inhibited in a rabbit intercalated cell line transfected with WNK4 or a WNK4 mutant found in individuals with FHHt. Coexpression of an epitope-tagged BK α-subunit with WNK4 or the WNK4 mutant in HEK293 cells reduced BK α-subunit plasma membrane and whole cell expression. A region within WNK4 encompassing the autoinhibitory domain and a coiled coil domain was required for WNK4 to inhibit BK α-subunit expression. The relative fraction of BK α-subunit that was ubiquitinated was significantly increased in cells expressing WNK4, compared with controls. Our results suggest that WNK4 inhibits BK channel activity, in part, by increasing channel degradation through an ubiquitin-dependent pathway. Based on these results, we propose that WNK4 provides a cellular mechanism for the coordinated regulation of two key secretory K+ channels in the distal nephron, ROMK and BK.
Enhanced adenosine A2b receptor signaling facilitates stimulus-induced catecholamine secretion in chronically hypoxic carotid body type I cells
Authors: Livermore Simon , Nurse Colin A.
Published: July 2013

Chronic hypoxia (CHox) augments chemoafferent activity in sensory fibers innervating carotid body (CB) chemoreceptor type I cells; however, the underlying mechanisms are poorly understood. We tested the hypothesis that enhanced paracrine signaling via adenosine (Ado) A2b receptors is involved. Dissociated rat CB cultures were exposed for 24 h to normoxia (Nox, 21% O2) or CHox (2% O2) or treated with the hypoxia mimetic deferoxamine mesylate (DFX), and catecholamine secretion from type I cells was monitored by amperometry. Catecholamine secretion was more robust in CHox and DFX type I cells than Nox controls after acute exposure to acid hypercapnia (10% CO2, pH 7.1) and high K+ (75 mM). Exogenous Ado increased catecholamine secretion in a dose-dependent manner, and the EC50 was shifted to the right from ∼21 μM Ado in Nox cells to ∼78 μM in CHox cells. Ado-evoked secretion in Nox and CHox cells was markedly inhibited by MRS-1754, an A2b receptor blocker, but was unaffected by SCH-58261, an A2a receptor blocker. Similarly, MRS-1754, but not SCH-58261, partially inhibited high-K+-evoked catecholamine secretion, suggesting a contribution from paracrine activation of A2b receptors by endogenous Ado. CB chemostimuli, acid hypercapnia, and hypoxia elicited a MRS-1754-sensitive rise in intracellular Ca2+ that was more robust in CHox and DFX than Nox cells. Taken together, these data suggest that paracrine Ado A2b receptor signaling contributes to stimulus-evoked catecholamine secretion in Nox and CHox CB chemoreceptors; however, the effects of Ado are more robust after CHox.
Selective leptin resistance revisited
Authors: Mark Allyn L.
Published: July 2013

In addition to effects on appetite and metabolism, leptin influences many neuroendocrine and physiological systems, including the sympathetic nervous system. Building on my Carl Ludwig Lecture of the American Physiological Society, I review the sympathetic and cardiovascular actions of leptin. The review focuses on a critical analysis of the concept of selective leptin resistance (SLR) and the role of leptin in the pathogenesis of obesity-induced hypertension in both experimental animals and humans. We introduced the concept of SLR in 2002 to explain how leptin might increase blood pressure (BP) in obese states, such as diet-induced obesity (DIO), that are accompanied by partial leptin resistance. This concept, analogous to selective insulin resistance in the metabolic syndrome, holds that in several genetic and acquired models of obesity, there is preservation of the renal sympathetic and pressor actions of leptin despite attenuation of the appetite and weight-reducing actions. Two potential overlapping mechanisms of SLR are reviewed: 1) differential leptin molecular signaling pathways that mediate selective as opposed to universal leptin action and 2) brain site-specific leptin action and resistance. Although the phenomenon of SLR in DIO has so far focused on preservation of sympathetic and BP actions of leptin, consideration should be given to the possibility that this concept may extend to preservation of other actions of leptin. Finally, I review perplexing data on the effects of leptin on sympathetic activity and BP in humans and its role in human obesity-induced hypertension.
Female SHR have greater blood pressure sensitivity and renal T cell infiltration following chronic NOS inhibition than males
Authors: Brinson Krystal N. , Elmarakby Ahmed A. , Tipton Ashlee J. , Crislip G. Ryan , Yamamoto Tatsuo , Baban Babak , Sullivan Jennifer C.
Published: July 2013

Nitric oxide is a critical regulator of blood pressure (BP) and inflammation, and female spontaneously hypertensive rats (SHR) have higher renal nitric oxide bioavailability than males. We hypothesize that female SHR will have a greater rise in BP and renal T cell infiltration in response to nitric oxide synthase (NOS) inhibition than males. Both male and female SHR displayed a dose-dependent increase in BP to the nonspecific NOS inhibitor NG-nitro-l-arginine methyl ester (l-NAME: 2, 5, and 7 mg·kg−1·day−1for 4 days each); however, females exhibited a greater increase in BP than males. Treatment of male and female SHR with 7 mg·kg−1·day−1l-NAME for 2 wk significantly increased BP in both sexes; however, prior exposure to l-NAME only increased BP sensitivity to chronic NOS inhibition in females. l-NAME-induced hypertension increased renal T cell infiltration and indices of renal injury in both sexes, yet female SHR exhibited greater increases in Th17 cells and greater decreases in regulatory T cells than males. Chronic l-NAME was also associated with larger increases in renal cortical adhesion molecule expression in female SHR. The use of triple therapy to block l-NAME-mediated increases in BP attenuated l-NAME-induced increases in renal T cell counts and normalized adhesion molecule expression in SHR, suggesting that l-NAME-induced increases in renal T cells were dependent on both increases in BP and NOS inhibition. Our data suggest that NOS is critical in the ability of SHR, females in particular, to maintain BP and limit a pro-inflammatory renal T cell profile.
Integration of thermal and osmotic regulation of water homeostasis: the role of TRPV channels
Authors: Sladek Celia D. , Johnson Alan Kim
Published: July 2013

Maintenance of body water homeostasis is critical for preventing hyperthermia, because evaporative cooling is the most efficient means of dissipating excess body heat. Water homeostasis is achieved by regulation of water intake and water loss by the kidneys. The former is achieved by sensations of thirst that motivate water acquisition, whereas the latter is regulated by the antidiuretic action of vasopressin. Vasopressin secretion and thirst are stimulated by increases in the osmolality of the extracellular fluid as well as decreases in blood pressure and/or blood volume, signals that are precipitated by water depletion associated with the excess evaporative water loss required to prevent hyperthermia. In addition, they are stimulated by increases in body temperature. The sites and molecular mechanisms involved in integrating thermal and osmotic regulation of thirst and vasopressin secretion are reviewed here with a focus on the role of the thermal and mechanosensitive transient receptor potential-vanilloid (TRPV) family of ion channels.