Fair allocation of utilities in multirate multicast networks: aframework for unifying diverse fairness objectives

We study fairness in a multicast network. We assume that different receivers of the same session can receive information at different rates. We study a fair allocation of utilities, where the utility of a bandwidth is an arbitrary function of the bandwidth. The utility function is not strictly increasing, nor continuous in general. We discuss fairness issues in this general context. Fair allocation of utilities can be modeled as a nonlinear optimization problem. However, nonlinear optimization techniques do not terminate in a finite number of iterations in general. We present an algorithm for computing a fair utility allocation. Using specific fairness properties, we show that this algorithm attains global convergence and yields a fair allocation in polynomial number of iterations     

The effect of arachidonic acid on junctional conductance in isolated murine hepatocytes

Arachidonic acid (AA) is known to inhibit intercellular conductance in normal and tumour cells. We showed that junctional conductance (Gj) in isolated murine hepatocytes was relatively tolerant to the uncoupling effect of AA. Extracellular application of 100 microM AA decreased Gj in less than 50% of hepatocytes, and the effect was much slower in other cells (10-15 min vs. 2-5 min, respectively). The uncoupling effect of AA did not depend on the intracellular [Ca2+] within the pCa(i) range 7.7-9.0. Similar results were obtained using the pipette-filling solutions with low (1 mM) and high (10 mM) concentrations of a Ca-chelating agent (EGTA). To verify whether the resistance of the hepatocyte Gj to AA may result from the "wash-out" of the intracellular intermediates during the intracellular dialysis, Gj was measured 10-45 min after the preincubation of hepatocytes with AA. After such a treatment, in 62% of cell pairs the Gj values recorded did not differ from the control. Extracellular or intracellular acidification (pHo 6.0 or pHi 5.0-6.0) did not markedly affect the AA action. However, in some cases AA induced the recovery of Gj blocked after intracellular acidification, the phenomenon suggesting the activation of the H+ transport in the presence of AA. Possible mechanisms of the observed resistance of junctional conductance of mouse hepatocytes in primary culture are discussed.     

Distribution of mRNA encoding the inwardly rectifying K+ channel, BIR1 in rat tissues

Chinese hamster P-glycoprotein ("multidrug-resistance protein") was purified and reconstituted in proteoliposomes by the procedure of I. L. Urbatsch, M. K. al-Shawi, and A. E. Senior (1994, Biochemistry 33, 7069-7076). The presence of lipid during the octylglucoside solubilization and Reactive Red 120 chromatography steps was found to be mandatory for retention of ATPase activity. Sheep brain or bovine liver lipid extracts could be substituted for the Escherichia coli lipids used previously. Stimulation of ATPase activity of purified, reconstituted P-glycoprotein by vinblastine, colchicine, and daunomycin was seen with sheep brain and bovine liver lipids, but not with E. coli lipids. Basal (i.e., not drug-stimulated) ATPase activity was different in the three lipids. Azidopine labeling of the drug binding sites in purified, reconstituted P-glycoprotein was carried out; vinblastine, colchicine, and daunomycin competed for labeling in all three lipids. It is therefore evident that the lipid environment can significantly influence the characteristics of purified, reconstituted P-glycoprotein ATPase activity and the apparent coupling between drug-binding and catalytic sites.     

In situ grown superconducting YBCO films on buffered silicon substrates for device applications

Thin films of YBa₂Cu₃O_7– (YBCO) have been grownin situ on silicon single-crystal (100) substrate by using SrTiO₃ as a buffer layer. The deposition has been carried out by on-axis rf magnetron sputtering method. The deposition condition have been optimized by studying the plasma characteristics and correlating them with the superconducting performance of the film. Films deposited at substrate temperature in the range of 680–700°C from stoichiometric YBCO targets in an argon + oxygen mixture (31) are superconducting and showc-axis epitaxy. Compositional confirmation has been carried out using Rutherford backscattering. Scanning tunneling microscopy of the films reveal formation of well-defined layered structure with some defects in the initial stages ofin situ growth of the films. Films grown on SrTiO₃ substrates have excellent crystalline quality (XRD), transition temperatureT _c0=81 K and the critical current densityJ _c >2×10⁵ A/cm² for unpatterned films at 77 K. On silicon substrates using buffer layers thein situ deposited YBCO films shows a higher transition width andT _c0 is also slightly less (71 K).     

Comparison of polarized and depolarized arrest in the isolated rat heart for long-term preservation

BACKGROUND: Hypothermic hyperkalemic cardioplegic solutions are currently used for donor heart preservation. Hyperkalemia-induced depolarization of the resting membrane potential (Em) may predispose the heart to Na+ and Ca2+ loading via voltage-dependent "window currents," thereby exacerbating injury and limiting the safe storage duration. Alternatively, maintaining the resting Em with a polarizing solution may reduce ionic movements and improve postischemic recovery; we investigated this concept with the reversible sodium channel blocker tetrodotoxin (TTX) to determine (1) whether polarized arrest was more efficacious than depolarized arrest during hypothermic long-term myocardial preservation and (2) whether TTX induces and maintains polarized arrest. METHODS AND RESULTS: The isolated crystalloid-perfused working rat heart preparation was used in this study. Preliminary studies determined an optimal TTX concentration of 22 micromol/L and an optimal storage temperature of 7.5 degrees C. To compare depolarized and polarized arrest, hearts were arrested with either Krebs-Henseleit (KH) buffer (control), KH buffer containing 16 mmol/L K+, or KH buffer containing 22 micromol/L TTX and then stored at 7.5 degrees C for 5 hours. Postischemic recovery of aortic flow was 13+/-4%, 38+/-2%, and 48+/-3%* (*P<.05 versus control and 16 mmol/L K+), respectively. When conventional 3 mol/L KCl-filled intracellular microelectrodes were used, Em gradually depolarized during control unprotected ischemia to approximately -55 mV before reperfusion, whereas arrest with 16 mmol/L K+ caused rapid depolarization to approximately -50 mV, where it remained throughout the 5-hour storage period. In contrast, in 22 micromol/L TTX-arrested hearts, Em remained more polarized, at approximately -70 mV, for the entire ischemic period. CONCLUSIONS: Blockade of cardiac sodium channels by TTX during ischemia maintained polarized arrest, which was more protective than depolarized arrest, possibly because of reduced ionic imbalance.     

A network selection method for handover in vehicle-to-infrastructure communications in multi-tier networks

Network selection is very important for a successful handover in a multi-tier heterogeneous networks. However, the primary challenges currently faced by research community is the lack of availability of network information at the mobile node side for efficiently select the most appropriate target network. It is practically difficult for an UE to get network information from base stations/access point of the neighbouring networks before connecting to them. In response to this, this paper proposes a network selection method that applies the knowledge of mobility data and the network load information to carry out an efficient handover for vehicle-to-infrastructure communication over multi-tier heterogeneous networks. We first derive key parameters, such as relative direction index, proximity index, residence time index, and network load index to select the best candidate network. A moving vehicle would be able to select the most appropriate target network by selecting one or more of the above parameters. We then test our algorithms by developing a dual mode vehicle On-Board Unit equipped with both Long Term Evolution-Advanced (LTE-A) and Wi-Fi network interface cards in OPNET simulator. The performance of the proposed handover method is evaluated by extensive OPNET-based simulation experiments. In the simulation model, we consider a multi-tier heterogeneous network comprising of a macro and multiple small cells of LTE-A and IEEE 802.11n technologies. Results show that our proposed handover method offers about 50% higher throughput and up to 43% higher packet delivery ratio than the conventional received signal strengths based network selection method.

     

MAAS: A mobile cloud assisted architecture for handling emergency situations

Recent advancements in the area of Mobile Cloud Computing (MCC) have significantly contributed towards assisting mankind to handle varied types of emergency situations that may arise as a result of different natural calamities like earthquakes, floods, fire, etc, which may cause huge damage to public property and result in loss of wealth of the nation. In this work, we have proposed a mobile cloud assisted architecture that supports the multicloud and hybrid‐cloud environments, together with Cloud Probing Service (CPS) and Cloud Ranking Service (CRS). The proposed algorithm consumes data from the sensor nodes and offloads the data to the most suitable cloud. A three‐layered architecture has been proposed, and the anchor points facilitate in the creation of the interface between the different layers. The simulation results indicate that the proposed mobile cloud assisted architecture for handling emergency situations (MAAS) approach performs better than the baseline algorithms.     

Tuning Contact Resistance in Top‐Contact p‐Type and n‐Type Organic Field Effect Transistors by Self‐Generated Interlayers

Contact resistance significantly limits the performance of organic field‐effect transistors (OFETs). Positioning interlayers at the metal/organic interface can tune the effective work‐function and reduce contact resistance. Myriad techniques offer interlayer processing onto the metal pads in bottom‐contact OFETs. However, most methods are not suitable for deposition on organic films and incompatible with top‐contact OFET architectures. Here, a simple and versatile methodology is demonstrated for interlayer processing in both p‐ and n‐type devices that is also suitable for top‐contact OFETs. In this approach, judiciously selected interlayer molecules are co‐deposited as additives in the semiconducting polymer active layer. During top contact deposition, the additive molecules migrate from within the bulk film to the organic/metal interface due to additive‐metal interactions. Migration continues until a thin continuous interlayer is completed. Formation of the interlayer is confirmed by X‐ray photoelectron spectroscopy (XPS) and cross‐section scanning transmission electron microscopy (STEM), and its effect on contact resistance by device measurements and transfer line method (TLM) analysis. It is shown that self‐generated interlayers that reduce contact resistance in p‐type devices, increase that of n‐type devices, and vice versa, confirming the role of additives as interlayer materials that modulate the effective work‐function of the organic/metal interface.     

Ab initio study of mono-layer 2-D insulators (X-(OH)2 and h-BN) and their use in MTJ memory device

The paper presents an ab initio study of the 2-D insulators and their effect on the performance of a magnetic tunnel junction memory (MTJ) device. MTJ devices has been considered as an alternate to the charge based data storage cells due to its spin-polarised operation and high scaling probability. The use of 2-D insulators like X-(OH)₂ (X: Ca and Mg) and h-BN (hexagonal-Boron Nitride) in such device would be interesting. The authors have calculated the band structures, density of states and effective mass of electrons and holes for the mono-layer of these three non-conventional 2-D insulators using the first principle calculations in density functional theory framework using Quantumwise ATK tool. The ab initio calculation yielded band gap (E_g) of 4.633, 4.685 and 4.249 eV for h-BN, Ca(OH)₂ and Mg(OH)₂, respectively. The effective mass of electrons was calculated as 0.621, 0.604 and 0.478 for single layer h-BN, Ca(OH)₂ and Mg(OH)₂, respectively. While for holes it is 0.834, 0.446 and 0.407, respectively for h-BN, Ca(OH)₂ and Mg(OH)₂. The MTJ device properties as tunneling-magneto resistance, differential TMR, parallel and anti-parallel resistance, differential resistance and spin transfer torque components (in-plane and out-of-plane) with these materials as composite dielectric has been reported in this paper using MTJ Lab tool. The performance of MTJ memory device with h-BN based composite dielectric is found better.

     

Fin shape influence on analog and RF performance of junctionless accumulation-mode bulk FinFETs

Microsystem Technologies - The non-planar 3D structure of multi-gate FinFETs makes them able to be scaled down to 20&nbsp;nm and beyond and also have greater performance. But any variation of...