Performance Analysis of Synchronous Duty-Cycled MAC Protocols

© 2015 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works.In this letter, we propose an analytical model to evaluate the performance of the S-MAC protocol. The proposed model improves the accuracy of previous models in two aspects. First, it incorporates the dependence among the nodes within a cluster by defining a DTMC that models the number of active nodes, whereas the previous models considered that nodes were mutually independent. Second, it proposes new methods for calculating packet delay and energy consumption. The analytical model is validated through discrete-event based simulations. Numerical results demonstrate that the proposed analytical model and methods yield accurate results under realistic assumptionsThis work was supported in part by the Spanish Government through project TIN2013-47272-C2-1-R. The associate editor coordinating the review of this paper and approving it for publication was J.-C. Chen.Martínez Bauset, J.; Guntupalli, L.; Li, F. (2015). Performance Analysis of Synchronous Duty-Cycled MAC Protocols. IEEE Wireless Communications Letters. 4(5):469-472. https://doi.org/10.1109/LWC.2015.2439267S4694724

Generation of attosecond electron bunches in a laser-plasma accelerator using a plasma density upramp

Attosecond electron bunches and attosecond radiation pulses enable the study of ultrafast dynamics of matter in an unprecedented regime. In this paper, the suitability for the experimental realization of a novel scheme producing sub-femtosecond duration electron bunches from laser-wakefield acceleration in plasma with self-injection in a plasma upramp profile has been investigated. While it has previously been predicted that this requires laser power above a few hundred terawatts typically, here we show that the scheme can be extended with reduced driving laser powers down to tens of terawatts, generating accelerated electron pulses with minimum length of around 166. attoseconds and picocoulombs charge. Using particle-in-cell simulations and theoretical models, the evolution of the accelerated electron bunch within the plasma as well as simple scalings of the bunch properties with initial laser and plasma parameters are presented

Structure-properties relationships in solution-processable single-material molecular emitters for efficient green organic light-emitting diodes

The electroluminescent properties of a series of solution-processable fluorescent molecular emitters have been systematically investigated. While the introduction of the electron-deficient benzothiadiazole unit in the structure confers efficient electron-injection on the emitter materials, they exhibit different hole-transport properties. The device characteristics of the OLEDs based on these various emitters are discussed on the basis of (i) the energy levels of their HOMO and LUMO and (ii) their hole-transport properties in relation with the charge-transport and blocking properties of the electron- and hole-transport layers. (C) 2012 Elsevier B.V. All rights reserved

A Cluster Method for the Ashkin--Teller Model

A cluster Monte Carlo algorithm for the Ashkin-Teller (AT) model is constructed according to the guidelines of a general scheme for such algorithms. Its dynamical behaviour is tested for the square lattice AT model. We perform simulations on the line of critical points along which the exponents vary continuously, and find that critical slowing down is significantly reduced. We find continuous variation of the dynamical exponent $z$ along the line, following the variation of the ratio $\alpha/\nu$, in a manner which satisfies the Li-Sokal bound $z_{cluster}\geq\alpha/\nu$, that was so far proved only for Potts models.Comment: 18 pages, Revtex, figures include

Compression Behavior of Biodegradable Thermoplastic Plasticizer-Containing Composites

Thermoplastic starch-based composites generate worldwide interest as they are based on green raw materials and undergo complete degradation. The composites were first fabricated from starch and sisal fibers as the major materials via the forming process. The effect of starches with different contents of single- and multicomponent plasticizers on the cushioning properties of the composites was studied. An increase in plasticizer contents within a certain range is shown to enhance materials resistance to pressure and its cushioning performance. With the multicomponent plasticizer content of 15%, the resistance to pressure for four types of composites prepared at different weight ratios of formamide and urea were of the order of 2:1>1:1>1:2, and that of the four types of composites fabricated at different weight ratios of glycerol and ethylene glycol were of the order of 1:2>2:1>1:1. Multicomponent plasticizer-containing starch-based composites are shown to be irregular elastomers and the stress-strain relation to be first defined by a hyperbolic tangent curve function and then by the tangent one.Композиты на основе термопластичного крахмала оказались в центре внимания как отечественных, так и зарубежных ученых, так как они основаны на экологичном сырье и полностью разлагаются. Такие композиты получали формовкой с использованием крахмала и сизалевых волокон в качестве основных материалов. Изучено влияние термопластичного крахмала с различной долей простых и составных пластификаторов на амортизационные свойства композитов. Экспериментальные результаты показали, что в определенных пределах с увеличением содержания пластификаторов повышаются сопротивление материала давлению и его амортизационные характеристики. При содержании составного пластификатора 15% сопротивление давлению четырех типов композитов, полученных с использованием различных массовых соотношений фомамида и мочевины, изменяется в ряду 2:1>1:1>1:2, а с использованием различных массовых соотношений глицерина и этиленгликоля в последовательности 1:2>2:1>1:1. Композиты на основе крахмала, содержащие составной пластификатор, являются нерегулярными эластомерами, и зависимость между напряжением и деформацией описывается в первую очередь функцией гиперболической тангенсоиды и во вторую очередь функцией тангенсоиды.Композити на основі термопластичного крохмалю виявилися в центрі уваги як вітчизняних, так і зарубіжних вчених, так як вони засновані на екологічної сировині і повністю розкладаються. Такі композити отримували формуванням з використанням крохмалю і сизалевих волокон в якості основних матеріалів. Вивчено вплив термопластичного крохмалю з різною часткою простих і складових пластифікаторів на амортизаційні властивості композитів. Експериментальні результати показали, що в певних межах зі збільшенням вмісту пластифікаторів підвищуються опір матеріалу тиску і його амортизаційні властивості. При утриманні складеного пластифікатора 15% опір тиску чотирьох типів композитів, отриманих з використанням різних масових співвідношень фомаміда і сечовини, змінюється в ряду 2: 1> 1: 1> 1: 2, а з використанням різних масових співвідношень гліцерину і етиленгліколю - в послідовності 1 : 2> 2: 1> 1: 1. Композити на основі крохмалю, які містять складовою пластифікатор, є нерегулярними еластомерами, і залежність між напруженням і деформацією описується в першу чергу функцією гіперболічної тангенсоіди і в другу чергу функцією тангенсоіди

Effect of sugar positions in ginsenosides and their inhibitory potency on Na+/K+-ATPase activity

Aim: To determine whether ginsenosides with various sugar attachments may act as active components responsible for the cardiac therapeutic effects of ginseng and sanqi (the roots of Panax ginseng and Panax notoginseng) via the same molecular mechanism triggered by cardiac glycosides, such as ouabain and digoxin. Methods: The structural similarity between ginsenosides and ouabain was analyzed. The inhibitory potency of ginsenosides and ouabain on Na+/K+-ATPase activity was examined and compared. Molecular modeling was exhibited for the docking of ginsenosides to Na+/K+-ATPase. Results: Ginsenosides with sugar moieties attached only to the C-3 position of the steroid-like structure, equivalent to the sugar position in cardiac glycosides, and possessed inhibitory potency on Na+/K+-ATPase activity. However, their inhibitory potency was significantly reduced or completely abolished when a monosaccharide was linked to the C-6 or C-20 position of the steroid-like structure; replacement of the monosaccharide with a disaccharide molecule at either of these positions caused the disappearance of the inhibitory potency. Molecular modeling and docking confirmed that the difference in Na+/K+-ATPase inhibitory potency among ginsenosides was due to the steric hindrance of sugar attachment at the C-6 and C-20 positions of the steroid-like structure. Conclusion: The cardiac therapeutic effects of ginseng and sanqi should be at least partly attributed to the effective inhibition of Na+/K+-ATPase by their metabolized ginsenosides with sugar moieties attached only to the C-3 position of the steroid-like structure

Inhibition of c-Jun NH2-terminal kinase stimulates mu opioid receptor expression via p38 MAPK-mediated nuclear NF-κB activation in neuronal and non-neuronal cells

AbstractDespite its potential side effects of addiction, tolerance and withdrawal symptoms, morphine is widely used for reducing moderate and severe pain. Previous studies have shown that the analgesic effect of morphine depends on mu opioid receptor (MOR) expression levels, but the regulatory mechanism of MOR is not yet fully understood. Several in vivo and in vitro studies have shown that the c-Jun NH2-terminal kinase (JNK) pathway is closely associated with neuropathic hyperalgesia, which closely resembles the neuroplastic changes observed with morphine antinociceptive tolerance. In this study, we show that inhibition of JNK by SP600125, its inhibitory peptide, or JNK-1 siRNA induced MOR at both mRNA and protein levels in neuronal cells. This increase in MOR expression was reversed by inhibition of the p38 mitogen-activated protein kinase (MAPK) pathway, but not by inhibition of the mitogen-activated protein/extracellular signal-regulated kinase (MEK) pathway. Further experiments using cell signaling inhibitors showed that MOR upregulation by JNK inhibition involved nuclear factor-kappa B (NF-κB). The p38 MAPK dependent phosphorylation of p65 NF-κB subunit in the nucleus was increased by SP600125 treatment. We also observed by chromatin immunoprecipitation (ChIP) analysis that JNK inhibition led to increased bindings of CBP and histone-3 dimethyl K4, and decreased bindings of HDAC-2, MeCP2, and histone-3 trimethyl K9 to the MOR promoter indicating a transcriptional regulation of MOR by JNK inhibition. All these results suggest a regulatory role of the p38 MAPK and NF-κB pathways in MOR gene expression and aid to our better understanding of the MOR gene regulation