DoS Attacks on Real-Time Media through Indirect Contention-in-Hosts

Quality of service (QoS) is critical for delivering real-time media services (RTMSs). The authors identify a new class of denial-of-service attacks against RTMSs — indirect contention-in-hosts (ICiH). Here, attackers attempt to indirectly degrade RTMS QoS by directing packets at other concurrent services, thereby inducing resource contention between RTMS packets and attack packets in the protocol stack. To analyze such attacks, the authors' operation-trace analysis method formalizes the notion of contention among concurrent services and develops several metrics to quantify ICiH's effects.     

Low shoot-through, high frequency CMOS driver for power controlapplications

The issue of `shoot-through' power dissipation is addressed and a pyramidal timing scheme is reported which reduces shoot-through power dissipation significantly. Measurements show reduction by a factor of 7 in the peak shoot-through power compared with a conventional driver     

Effect of Buffer Layer on the Properties of Laser Ablated PZT Thin Films

Lead zirconate titanate (PbZr _x Ti_1?x O₃) or PZT ceramics are a class of piezoelectric materials that are currently experiencing widespread use in industry as electromechanical devices. PtSi/ZnO/PZT thin films were deposited by pulsed laser deposition at relatively low substrate temperature. The PZT thin films on PtSi substrates and on ZnO buffer layer were deposited at substrate temperature 300°C. The composition analysis shows that the film deposited at low temperature is stoichiometric. The films exhibit ferroelectric nature with coercive field of 19.6 kV/cm for 800 nm thick film. The leakage current density of the films shows a good insulating behavior.     

Growth of ITO thin films on polyimide substrate by bias sputtering

Transparent conducting indium tin oxide thin films were deposited on polyimide substrates by RF bias sputtering of ITO target. The influences of bias voltage on the structural and electrical properties of the films were investigated. In order to correlate the material characteristics with the plasma parameters during sputtering, we employed Langmuir probe and optical emission spectral studies. The films deposited onto positively biased substrates were poorly crystalline. An improvement in crystallinity was observed with increase in negative bias. The films deposited at a bias voltage of ?20 V showed a preferred orientation in the [1 1 1] direction and has minimum resistivity compared to films grown at other biasing conditions. The measured plasma parameters were correlated to the film properties. The ITO films thus grown have been used as the channel layer for the fabrication of thin film transistor.     

The JNK pathway regulates the In vivo deletion of immature CD4(+)CD8(+) thymocytes

The extracellular signal-regulated kinase (ERK), the c-Jun NH2-terminal kinase (JNK), and p38 MAP kinase pathways are triggered upon ligation of the antigen-specific T cell receptor (TCR). During the development of T cells in the thymus, the ERK pathway is required for differentiation of CD4(-)CD8(-) into CD4(+)CD8(+) double positive (DP) thymocytes, positive selection of DP cells, and their maturation into CD4(+) cells. However, the ERK pathway is not required for negative selection. Here, we show that JNK is activated in DP thymocytes in vivo in response to signals that initiate negative selection. The activation of JNK in these cells appears to be mediated by the MAP kinase kinase MKK7 since high levels of MKK7 and low levels of Sek-1/MKK4 gene expression were detected in thymocytes. Using dominant negative JNK transgenic mice, we show that inhibition of the JNK pathway reduces the in vivo deletion of DP thymocytes. In addition, the increased resistance of DP thymocytes to cell death in these mice produces an accelerated reconstitution of normal thymic populations upon in vivo DP elimination. Together, these data indicate that the JNK pathway contributes to the deletion of DP thymocytes by apoptosis in response to TCR-derived and other thymic environment- mediated signals.     

Optimisation of consolidation and whey drainage during the process of Paneer pressing

Test cells of various profiles (circular, square, rectangle) were designed to conduct experiments to evaluate consolidation mechanism and drainage of whey during Paneer pressing. The milk coagulum was subjected to different pressure levels (1.0–3.5 kg/cm²) for different time periods (300, 600, 900 s). The non-dimensional whey expression ratio (WER) during pressing followed an exponential relationship with pressure, and the maximum value for WER ranged from 20.5 to 23.0 for the test cells. The visco-elastic consolidation process was adequately described using Kevin–Voigt models. The void ratio, porosity and consolidation ratio were estimated by the Terzaghi consolidation test.     

Exergy analysis of direct expansion solar‐assisted heat pumps using artificial neural networks

Artificial neural network (ANN) is applied for exergy analysis of a direct expansion solar‐assisted heat pump (DXSAHP) in the present study. The experiments were conducted in a DXSAHP under the meteorological conditions of Calicut city in India. An ANN model was developed based on backpropagation learning algorithm for predicting the exergy destruction and exergy efficiency of each component of the system at different ambient conditions (ambient temperature and solar intensity). The experimental data acquired are used for training the network. The results showed that the network yields a maximum correlation coefficient with minimum coefficient of variance and root mean square values. The results confirmed that the use of an ANN analysis for the exergy evolution of DXSAHP is quite suitable. Copyright © 2009 John Wiley & Sons, Ltd.     

The photoluminescence of SrS:Cu nanophosphor

Strontium sulfide doped with copper has been regarded as one of the most promising inorganic materials for the blue-green color phosphor. A wet chemical precipitation method with post-annealing is presented for the synthesis of copper-doped SrS nanoparticles. XRD studies revealed the phase purity of SrS particles with rocksalt structure. TEM images showed the formation of nanoparticles with an average size of 7?nm. Green photoluminescence emission (PL) at 535?nm was observed for an excitation wavelength of 356?nm, the intensity of which was greater than that of coarser phosphor particles synthesized by solid state reaction. Low temperature PL showed a redshift with decreasing temperature which is due to aggregated copper centers. Luminescent decay at room temperature was found to be faster than the reported values of the corresponding transition in thin film samples. A blueshift in the absorption edge was observed for the nanophosphor with respect to the bulk due to reduction in particle size.     

Spectrophotometric determination of V(V) in environmental, biological, pharmaceutical and alloy samples by novel oxidative coupling reactions

A Novel, rapid, sensitive and selective reactions are developed for spectrophotometric determination of trace amounts of vanadium (V) in environmental, biological, pharmaceutical and alloy samples was studied. The methods were based on interactions of 4-bromophenyl hydrazine (4-BPH) with N-(1-naphthyl ethylenediamine dihydrochloride (NEDA) in the presence of vanadium in acidic medium (acetate buffer of pH 3.0) to give violet colored derivative or on the oxidation of 4-bromophenyl hydrazine by vanadium in basic medium and coupling with chromotropic acid (CA) to yield red color derivative. The violet color derivative having an absorbance maximum at 570nm which is stable for 7 days and the red derivative with lambda(max) 495nm for 5 days. Beer's law was obeyed for vanadium in the concentration range of 0.5-6.0microgml(-1) (violet derivative) and 0.6-7.0microgml(-1) (red derivative), respectively. The optimum reaction conditions and other important analytical parameters were established to enhance the sensitivity of the proposed methods. Interference due to various non-target ions was also investigated. The proposed methods were applied to the analysis of vanadium (V) in environmental, biological, pharmaceutical and steel samples. The performance of proposed methods were evaluated in terms of Student's t-test and Variance ratio F-test that indicates the significance of proposed methods over reported method.