Low IP Research Articles

The role of the plasma current in turbulence decrease during lower hybrid current drive

The interaction of radio frequency (RF) waves with edge turbulence has resurfaced after the results obtained on many tokamaks showing that edge turbulence decreases when the ion cyclotron frequency heating (ICRH) is switched on. Using the lower hybrid (LH) waves to drive current into tokamak plasmas, this issue presented contradicting results with some tokamaks (FTU & HT-7) showing a net decrease, similar to the ICRH results, and others (Tore Supra) did not. In this article, these apparent discrepancies among tokamaks and RF wave frequencies are removed. It is found that turbulence large-scale structures in the scrape-off layer decrease at high enough plasma currents (Ip) on the Tore Supra tokamak. We distinguish three regimes: At low Ip's, no modification is detected with statistical properties of turbulence similar to ohmic plasmas even with PLH reaching 4.8 MW. At moderate plasma currents, turbulence properties are modified only at a high LH power. At high plasma currents, turbulent large scales are reduced to values smaller than 1 cm, and this is accompanied by a net decrease in the level of turbulence of about 30% even with a moderate LH power.

CFO Country of Origin and Accounting Quality. A Cross-Country Investigation

Prior research has analyzed accounting quality around the world only working on institutional differences mainly at country level. Little research has been devoted to top management cultural values (here defined as CFO’s country of origin), which has turned out to be able to generate unique results on firms’ outcomes. In this work, building a unique hand collected dataset based on 954 unique CFOs across Europe and 4,478 firm-year observations I investigate the effect of CFO country of origin on accounting quality in the European Union. My findings show first, as a validity test, that there is a CFO fixed effect on accounting quality also in a cross-country setting (i.e. outside the US). Then, I show that in the EU foreign CFOs are able to foster accounting quality relative to local peers. Moreover, working on economies clusters I find that CFOs working in insider economies, but born elsewhere (outside this area) are able to marginally improve accounting quality for the firm they work with. On the contrary, this does not apply if a CFO born in an insider economy works outside his area of birth. Finally, working on CFO turnover, I find that overall CFO changes have an effect on accruals quality level. Nonetheless, cross-sectional tests reveal that such changes are significant when CFO turnover happens from CFO born in a low (high) IP country to a CFO born in a high (low) IP country, where accounting quality improves (worsens).

Thermodynamic analysis of drying process in a diagonal-batch dryer developed for batch uniformity using potato slices

Optimized air distribution is important for the energy consumption in a batch drying process. Energy and exergy analyses for an innovative diagonal-batch dryer were performed using potato slices of 5 mm and 8 mm thicknesses at 55 °C and 65 °C. The exergetic efficiency, improvement potential rate (IP) and exergetic factor (f) were taken as performance parameters. The main component for improving the system efficiency was found to be the fan–heater combination, possessing low exergy efficiency, high IP and high f values. The energy utilization, energy utilization ratio, exergy losses and exergy efficiency varied between 1.82 and 12.52 kJ/s, 0.04–0.59, 1.3–4.89 kJ/kg and 0.41–0.94, respectively for potato slices. The specific evaporation energy and specific product energy were found to be in the range of 4.78–6.13 MJ/kg and 16.24–20.63 MJ/kg respectively. The outcomes of the analysis will provide insights into the optimization of a batch dryer for the maximum retention of quality parameters and energy saving.

Co- and counter-current rotation in Tore Supra lower hybrid current drive plasmas

Observations of lower hybrid (LH) radio frequency heating effects on toroidal plasma rotation in L-mode Tore Supra plasmas are reported. A database of more than 50 plasma discharges has been analysed. Core rotation is found to increment in co- or counter-current direction depending on the plasma current (Ip). At low plasma current, the induced rotation is up to +15 km s−1 in the co-current direction, the rotation profile being affected over the whole plasma minor radius. At higher plasma current, an opposite trend is observed, the core plasma rotation incrementing up to −15 km s−1 in the counter-current direction, the profile being affected up to r/a < 0.6 only. At the zero crossing point, which is defined when the plasma rotation profile is not affected by LH power injection, Ip ∼ 0.95 MA. In both low and high Ip cases, rotation increments are found to increase with the injected power. Several mechanisms in competition which can induce co- or counter-current rotation in Tore Supra LHCD plasmas are investigated and typical order of magnitude are discussed. How those effects evolve with plasma parameters and how they compete are important issues addressed in this paper. Rotation increment increase with Ip at fixed LH power is consistent with a dominant standard momentum confinement mechanism related to Ip increase. The co-current change in rotation is consistent with a fast electron ripple loss mechanism, while thermal ripple induced neoclassical friction and absorbed LH wave momentum from resonant electrons are expected to influence the rotation in the counter-current direction. Finally, the numerical simulations show that the radial turbulent momentum transport does impact the rotation behaviour inducing increment in co- or counter-current directions, depending on the plasma current amplitude.

Resistance to thyroid hormone due to mutations in the THRB gene impairs bone mass and affects calcium and phosphorus homeostasis

ContextResistance to thyroid hormone (RTH) is an inherited syndrome of reduced tissue responsiveness to thyroid hormone, which is usually due to mutations in the thyroid hormone receptor β gene (THRB). Few studies have been conducted to investigate bone and mineral metabolism in RTH. ObjectiveThe objective of the study was to evaluate the clinical and biochemical parameters related to bone and mineral metabolism in RTH due to mutations in the THRB gene (RTHβ). Design and participantsWe conducted a cross-sectional study on 14 patients with RTHβ (RTHG), eight adults and six children, and 24 control subjects (CG). OutcomesSerum measures included total calcium (TCa), inorganic phosphate (iP), alkaline phosphatase (AP), parathyroid hormone (PTH), 25-hydroxyvitamin D (25OHD), osteocalcin (OC), carboxyterminal telopeptide (CTX), and fibroblast growth factor 23 (FGF-23). We estimated the renal threshold phosphate concentration (TmPO4/GFR) and assessed bone mass using dual X-ray absorptiometry. ResultsAdults and children with RTH showed higher serum levels of TCa than controls (P=.029 and, P=.018 respectively). However, only children with RTH exhibited lower serum levels of iP than controls (P=.048). FGF-23 was higher in RTHβ children (P=.04). RTHβ adults had lower whole-body (P=.01) and lumbar spine (P=.01) bone mineral density than control subjects. The same pattern was observed when the results were expressed as Z-scores between groups, with a lower value in RTHG than in CG for the lumbar spine of adults (P=.03). No difference was observed between groups in PTH, 25OHD, AP, OC, and CTX. ConclusionBiochemical abnormalities are seen in children with RTH (Low iP, high FGF23), while high calcium (with normal UCa) is seen in RTH subjects of all ages, and later on, in adult life, low BMD is seen. Considering that the TRα1 isoform is the predominant TR in the skeleton, we hypothesize that probably these patients may exhibit enhanced calcium flux from bone to circulation. Our data represent a challenge for new studies to unveil the control of calcium and phosphorus homeostasis and fracture risk in these patients.

Platelet-derived serotonin: Translational implications for liver regeneration

Platelet-derived serotonin: Translational implications for liver regeneration

The effects of increasing lithium deposition on the power exhaust channel in NSTX

Previous measurements on the National Spherical Torus Experiment (NSTX) demonstrated peak, perpendicular heat fluxes, qdep,pk⩽15 MW m−2 with an inter-edge localized mode integral heat flux width, during high performance, high power operation (plasma current, Ip = 1.2 MA and injected neutral beam power, PNBI = 6 MW) when magnetically mapped to the outer midplane. Analysis indicates that scales approximately as . The extrapolation of the divertor heat flux and λq for NSTX-U are predicted to be upwards of 24 MW m−2 and 3 mm, respectively assuming a high magnetic flux expansion, fexp ∼ 30, PNBI = 10 MW, balanced double null operation and boronized wall conditioning. While the divertor heat flux has been shown to be mitigated through increased magnetic flux expansion, impurity gas puffing, and innovative divertor configurations on NSTX, the application of evaporative lithium coatings in NSTX has shown reduced peak heat flux from 5 to 2 MW m−2 during similar operation with 150 and 300 mg of pre-discharge lithium evaporation respectively. Measurement of divertor surface temperatures in lithiated NSTX discharges is achieved with a unique dual-band IR thermography system to mitigate the variable surface emissivity introduced by evaporative lithium coatings. This results in a relative increase in divertor radiation as measured by divertor bolometry. While the measured divertor heat flux is reduced with strong lithium evaporation, λq contracts to 3–6 mm at low Ip but remains nearly constant as Ip is increased to 1.2 MA yielding λq's comparable to no lithium discharges at high Ip.

Characterization of lead glazed potteries from Smyrna (Izmir/Turkey) using multiple analytical techniques; Part I: Glaze and engobe

Eighteen lead glazed potsherds from the Ayasuluk region (Smyrna) were characterized in order to have detailed knowledge of their production technology. Micro-Raman and scanning electron microscopy (SEM) with the combination of an energy dispersive X-ray spectrometer (EDX) was used for their characterization. EDX analysis of the glaze layers showed that lead oxide was used as a fluxing agent for the production of most of the potsherds. Microstructural characteristics such as rod-shaped crystals at the interaction layers, residual quartz crystals inside the glaze layers and coloration of the decorations of the potsherds were also evaluated in the study. Furthermore, micro-Raman spectra provided bases for evaluation of firing temperature of the glazes based on the polymerization index (Ip) values. The low Ip values, for all of the analyzed samples (except for two of them), indicated that the glazes were rich in lead oxide and should have been fired at temperatures below 700°C. In the Raman spectra of the glazes, several pigments and/or colored minerals were identified: These were namely lead white, anatase, quartz, calcite, red ocher, lazurite and carbon black.

Object shift in Romance

This paper discusses the properties of VOS sentences in Romance and their bearing on Case assignment, verb movement, parametric variation, and the structure of the vP periphery / low IP area. The literature on Romance VOS has argued that this order is derived either through object shift (Ordonez 1997, 1998, 2000) or VP fronting (Belletti 2001, 2004; Zubizarreta 1998), providing empirical evidence in support of both derivations. In this paper, I focus on various aspects of VOS sentences in Romance languages. First, I argue that both object shift and VP-fronting strategies are actually available, but subject to a very specific parametric cut: Western Romance languages (Galician, European Portuguese, and Spanish) resort to object shift, whereas Central-Eastern varieties (Catalan and Italian) fail to do so, requiring the VP-fronting derivation instead (Lopez 2009a). Second, I put forward a previously unnoticed generalization that reveals that only those varieties licensing object shift based VOS can generate VSO sentences, which I refer to as the VOS–VSO Generalization. Finally, I claim that object shift in VOS sentences of Western Romance languages displays a cluster of unnoticed properties that pattern with Scandinavian-style object shift (Bobaljik and Jonas 1996; Bobaljik and Thrainsson 1998; Collins and Thrainsson 1996; Holmberg 1986, 1999; Vikner 2006), thus obeying Holmberg’s Generalization (Holmberg 1986, 1999). If on track, the present account not only reveals interesting syntactic similarities between Scandinavian and Romance object shift, but also reinforces a well-known micro-parameter that disentangles Western from Central-Eastern Romance languages.

Road Map and Challenges in 4G Wireless System

The user demand for high speed multi-media application has been increasing many folds in the recent years. New smart phones are launching in the market. The wireless communication is looking forward for a new generation technology that will match the application demand and resources. This is where the fourth generation (4G) wireless communication is required. 4G wireless communication is expected to provide better speed, high capacity, low cost IP based services. The main objective of the 4G wireless communication is to supersede the current core technology with a single unified technology. More and more advanced interactive multimedia applications are emerging as 4G networks resulting in a rapid development of video coding and communication techniques. This paper deals with the current scenario and the future prospects of the 4G system in addition with the challenges it is going to witness.

Low latency IP mobility management: protocol and analysis

Mobile IP is one of the dominating protocols that enable a mobile node to remain reachable while moving around in the Internet. However, it suffers from long handoff latency and route inefficiency. In this article, we present a novel distributed mobility management architecture, ADA (Asymmetric Double-Agents), which introduces double mobility agents to serve one end-to-end communication. One mobility agent is located close to the MN and the other close to the CN. ADA can achieve both low handoff latency and low transmission latency, which is crucial for improvement of user perceived QoS. It also provides an easy-to-use mechanism for MNs to manage and control each traffic session with a different policy and provide specific QoS support. We apply ADA to MIPv6 communications and present a detailed protocol design. Subsequently, we propose an analytical framework for systematic and thorough performance evaluation of mobile IP-based mobility management protocols. Equipped with this model, we analyze the handoff latency, single interaction delay and total time cost under the bidirectional tunneling mode and the route optimization mode for MIPv6, HMIPv6, CNLP, and ADA. Through both quantitative analysis and NS2-based simulations, we show that ADA significantly outperforms the existing mobility management protocols.

Low Cost IP Private Branch Exchange 'PBX'

The drawback of EAPBX system is that it required extra wiring and the extensions are very difficult to manage. The solution to this problem is the use of Internet protocol which carries voice as a data called “Voice over Internet Protocol”. The advantage of this system is that it uses the existing network connection installed for the organization and the management of the extensions are very easy as it can be manages from the web browser. The system is cost efficient as it uses only one computer system as a server with Linux based operating system called “trixbox”. The system uses the USB handset as an interfacing device like telephone. General Terms Voice over Internet Protocol and Session Initiation Protocol i.e. SIP based client server system architecture is the base of the system. The System is compatible for LAN, MAN and WAN. This system also supports the Voice over WiFi Network if the organization consists of WiFi campus.

Development of a plasma current ramp-up technique for spherical tokamaks by the lower hybrid wave

Spherical tokamaks (STs) have the advantage of high beta capability, but the realization of a compact reactor requires the elimination of the central solenoid (CS). The possibility of using the lower hybrid wave (LHW) to ramp up the plasma current (Ip) from zero to a high enough level required for fusion burn in ST is examined theoretically and experimentally. Excitation of a travelling fast wave (FW) by the combline antenna installed on TST-2 was confirmed by a finite element analysis, but efficient current drive requires excitation of the LHW, either directly by the antenna or by mode conversion from the FW. The analysis using the TORLH full-wave solver indicates that core current drive by LHW is possible in the low-density, low Ip plasma formed by electron cyclotron heating (ECH). It is important to keep the density low during Ip ramp-up, and the wavenumber must be reduced as Ip increases. Initial results from TST-2 demonstrate that RF power in the LH frequency range (200 MHz) can achieve initial Ip formation, and is more effective than ECH for further ramp-up of Ip. Ip ramp-up to over 12 kA was achieved by combining ramp-up of the externally applied vertical magnetic field and ramp-up of the RF power. The significant asymmetry observed between co-current drive and counter-current drive is attributed to the presence of RF driven current. An optimized LHW antenna with appropriate polarization and wavenumber spectrum controllability is being designed. The success of the TST-2 experiment would provide a scientific basis for quantitatively evaluating the required CS capability for a low-aspect-ratio reactor.

Synthesis and characterization of phenanthroimidazole derivatives for applications in organic electroluminescent devices

A series of phenanthroimidazole derivatives have been synthesized, characterized and applied as non-doped emitters in organic light-emitting devices. The compounds show high fluorescent quantum yields up to 0.75 as well as good thermal and film-forming abilities. Crystal structures of the compounds were determined by X-ray crystallography. Correlations between optoelectronic properties, energy levels and molecular structures of the materials were investigated. It was found that introduction of a thiophene ring on the C2-position of phenanthroimidazole can effectively decrease the ionization potentials (Ip) of the compounds. Fluorescent properties of the materials were found to be related to the dihedral angles in the compounds with different substituents. The low Ip (from 5.00 to 5.21 eV) of the materials enables efficient hole-injection from the hole-transporting layer and results in low turn-on (<2.7 V) and operation voltages (<5.5 V to give 1000 cd m−2).

Modulation of Myocardin Function by the Ubiquitin E3 Ligase UBR5

Fully differentiated mature smooth muscle cells (SMCs) are characterized by the presence of a unique repertoire of smooth muscle-specific proteins. Although previous studies have shown myocardin to be a critical transcription factor for stimulating expression of smooth muscle-specific genes, the mechanisms regulating myocardin activity are still poorly understood. We used a yeast two-hybrid screen with myocardin as bait to search for factors that may regulate the transcriptional activity of the myocardin. From this screen we identified a HECT domain-containing protein UBR5 (ubiquitin protein ligase E3 component n-recognin 5) as a myocardin-binding protein. Previous studies have shown that HECT domain-containing proteins are ubiquitin E3 ligases that play an important role in protein degradation. UBR5 has, however, also been shown to regulate transcription independent of its E3 ligase activity. In the current study we demonstrated that UBR5 localized in the nuclei of SMCs and forms a complex with myocardin in vivo and in vitro. We also show that UBR5 specifically enhanced trans-activation of smooth muscle-specific promoters by the myocardin family of proteins. In addition, UBR5 significantly augmented the ability of myocardin to induce expression of endogenous SMC marker genes independent on its E3 ligase function. Conversely, depletion of endogenous UBR5 by small interfering RNA in fibroblast cells attenuated myocardin-induced smooth muscle-specific gene expression, and UBR5 knockdown in SMCs resulted in down-regulation of smooth muscle-specific genes. Furthermore, we found that UBR5 can attenuate myocardin protein degradation resulting in increased myocardin protein expression without affecting myocardin mRNA expression. The effects of UBR5 on myocardin requires only the HECT and UBR1 domains of UBR5. This study reveals an unexpected role for the ubiquitin E3 ligase UBR5 as an activator of smooth muscle differentiation through its ability to stabilize myocardin protein.

Rappel: Exploiting interest and network locality to improve fairness in publish-subscribe systems

In this paper, we present the design, implementation and evaluation of Rappel, a peer-to-peer feed-based publish-subscribe service. By using a combination of probabilistic and gossip-like techniques and mechanisms, Rappel provides noiselessness, i.e., updates from any feed are received and relayed only by nodes that are subscribers of that feed. This leads to a fair system: the overhead at each subscriber node scales with the number and nature of its subscriptions. Moreover, Rappel incurs small publisher and client overhead, and its clients receive updates quickly and with low IP stretch. To achieve these goals, Rappel exploits ''interest locality'' characteristics observed amongst real multi-user multi-feed populations. This is combined with systems design decisions that enable nodes to find other subscribers, and maintain efficient network locality-aware dissemination trees. We evaluate Rappel via both trace-driven simulations and a PlanetLab deployment. The experimental results from the PlanetLab deployment show that Rappel subscribers receive updates within hundreds of milliseconds after posting. Further, results from the trace-driven simulator match our PlanetLab deployment, thus allowing us to extrapolate Rappel's performance at larger scales.

Role of the Prostanoid EP4 Receptor in Iloprost-mediated Vasodilatation in Pulmonary Hypertension

Iloprost is effective for the treatment of pulmonary hypertension. It acts through elevation of cAMP by binding to the prostacyclin receptor (IP receptor). However, there is evidence that patients with severe pulmonary hypertension have decreased expression of the IP receptor in the remodeled pulmonary arterial smooth muscle. We hypothesized that prostanoid receptors other than the IP receptor are involved in signal transduction by iloprost. Immunoblotting was used to detect the IP and prostanoid EP4 receptor in lung tissue from patients with idiopathic pulmonary arterial hypertension, and immunohistochemistry was used to detect these receptors in lung sections from rats treated with monocrotaline (MCT28d). Protein and mRNA were isolated from pulmonary arterial smooth muscle cells (PASMCs) from control and MCT28d rats treated with AH6809 (an EP2 receptor antagonist) and AH23848 (an EP4 receptor antagonist) in combination with iloprost. Intracellular cAMP was also assessed in these tissues. IP receptor expression was reduced in idiopathic pulmonary arterial hypertension patient lung samples and MCT28d rat lungs compared with the controls. Reverse transcriptase-polymerase chain reaction and immunoblotting of MCT28d rat PASMC extracts revealed scant expression of the IP receptor but stable expression of EP4 receptor, compared with controls. Iloprost-induced elevation in intracellular cAMP in PASMCs was dose-dependently reduced by AH23848, but not by AH6809. Iloprost mediates vasodilatory functions via the EP4 receptor in the case of low IP receptor expression associated with pulmonary arterial hypertension. This is a previously unrecognized mechanism for iloprost, and illustrates that the EP4 receptor may be a novel therapeutic approach for the treatment of pulmonary arterial hypertension.

A Study on Ultra Low-Latency Mobile Networks

Traffic demand for real-time services as well as non real-time services has recently been increasing, due to the rapid improvement in transmission bit-rate within communication networks. In the future ubiquitous network society, in addition to traffic demand for user-to-user real-time communications services, traffic of real-time applications is set to explode due to new communications traffic for machine-to-machine communications. This paper proposes "ultra low-latency mobile networks," where the target value for unidirectional end-to-end latency per IP packet is 10 ms, in order to establish a new communications infrastructure capable of providing next-generation real-time services. This paper introduces a model of such ultra low-latency mobile networks and the results of a feasibility study are also presented. The simulation study shows the potential to realize a mobile network with ultra low-latency of less than 10 ms for IP packets and a low IP packet error rate of < 0.1% through simulations. A test-bed developed to measure actual latency is also introduced in this paper as well as measurement results using this test-bed. The measurement results also confirm the possibility indicated by the simulation studies.

A Novel Role of Brg1 in the Regulation of SRF/MRTFA-dependent Smooth Muscle-specific Gene Expression

Serum response factor (SRF) is a key regulator of smooth muscle differentiation, proliferation, and migration. Myocardin-related transcription factor A (MRTFA) is a co-activator of SRF that can induce expression of SRF-dependent, smooth muscle-specific genes and actin/Rho-dependent genes, but not MAPK-regulated growth response genes. How MRTFA and SRF discriminate between these sets of target genes is still unclear. We hypothesized that SWI/SNF ATP-dependent chromatin remodeling complexes, containing Brahma-related gene 1 (Brg1) or Brahma (Brm), may play a role in this process. Results from Western blotting and qRT-PCR analysis demonstrated that dominant negative Brg1 blocked the ability of MRTFA to induce expression of smooth muscle-specific genes, but not actin/Rho-dependent early response genes, in fibroblasts. In addition, dominant negative Brg1 attenuated expression of smooth muscle-specific genes in primary cultures of smooth muscle cells. MRTFA overexpression did not induce expression of smooth muscle-specific genes in SW13 cells, which lack endogenous Brg1 or Brm. Reintroduction of Brg1 or Brm into SW13 cells restored their responsiveness to MRTFA. Immunoprecipitation assays revealed that Brg1, SRF, and MRTFA form a complex in vivo, and Brg1 directly binds MRTFA, but not SRF, in vitro. Results from chromatin immunoprecipitation assays demonstrated that dominant negative Brg1 significantly attenuated the ability of MRTFA to increase SRF binding to the promoters of smooth muscle-specific genes, but not early response genes. Together these data suggest that Brg1/Brm containing SWI/SNF complexes play a critical role in regulating expression of SRF/MRTFA-dependent smooth muscle-specific genes but not SRF/MRTFA-dependent early response genes.

Probing of Toroidal Electron Plasmas Confined on Helical Magnetic Surfaces

With a skillful probing system, both large negative space potential φs and low electron current Ip of helical nonneutral plasmas have been measured. For the φs measurement, a differential circuit with a high-voltage probe is employed. In order to prevent the signal from delaying due to the large output impedance of the high-voltage probe, an operational amplifier is used to reduce the output impedance to ideally zero. For the Ip measurement, an instrumentation amplifier is employed to precisely cancel the common-mode noise. In addition, to alleviate the thermal noise due to the large feedback resistance in the circuit, a trick of T-network resistance is utilized instead of the single large resistance. Furthermore, to cancel the significant ground loop current, the reference potential of the circuit is grounded across a small resistance (100Ω).