Perturbative Wilson loops from unquenched Monte Carlo simulations at weak couplings

Perturbative expansions of several small Wilson loops are computed through next-to-next-to-leading order in unquenched lattice QCD, from Monte Carlo simulations at weak couplings. This approach provides a much simpler alternative to conventional diagrammatic perturbation theory, and is applied here for the first time to full QCD. Two different sets of lattice actions are considered: one set uses the unimproved plaquette gluon action together with the unimproved staggered-quark action; the other set uses the one-loop-improved Symanzik gauge-field action together with the so-called ``asqtad'' improved-staggered quark action. Simulations are also done with different numbers of dynamical fermions. An extensive study of the systematic uncertainties is presented, which demonstrates that the small third-order perturbative component of the observables can be reliably extracted from simulation data. We also investigate the use of the rational hybrid Monte Carlo algorithm for unquenched simulations with unimproved-staggered fermions. Our results are in excellent agreement with diagrammatic perturbation theory, and provide an important cross-check of the perturbation theory input to a recent determination of the strong coupling $\alpha_{\bar{\rm MS}}(M_Z)$ by the HPQCD collaboration.Comment: 14 pages, 8 figure

Analysis of pion elliptic flows and HBT interferometry in a granular quark-gluon plasma droplet model

In many simulations of high-energy heavy-ion collisions on an event-by-event analysis, it is known that the initial energy density distribution in the transverse plane is highly fluctuating. Subsequent longitudinal expansion will lead to many longitudinal tubes of quark-gluon plasma which have tendencies to break up into many spherical droplets because of sausage instabilities. We are therefore motivated to use a model of quark-gluon plasma granular droplets that evolve hydrodynamically to investigate pion elliptic flows and Hanbury-Brown-Twiss interferometry. We find that the data of pion transverse momentum spectra, elliptic flows, and HBT radii in \sqrt{s_{NN}}=200 GeV Au + Au collisions at RHIC can be described well by an expanding source of granular droplets with an anisotropic velocity distribution.Comment: 9 pages, 6 figures, in Late

Adaptive and intelligent navigation of autonomous planetary rovers - A survey

The application of robotics and autonomous systems in space has increased dramatically. The ongoing Mars rover mission involving the Curiosity rover, along with the success of its predecessors, is a key milestone that showcases the existing capabilities of robotic technology. Nevertheless, there has still been a heavy reliance on human tele-operators to drive these systems. Reducing the reliance on human experts for navigational tasks on Mars remains a major challenge due to the harsh and complex nature of the Martian terrains. The development of a truly autonomous rover system with the capability to be effectively navigated in such environments requires intelligent and adaptive methods fitting for a system with limited resources. This paper surveys a representative selection of work applicable to autonomous planetary rover navigation, discussing some ongoing challenges and promising future research directions from the perspectives of the authors

Efficient Ultra High Voltage Controller Based Complementary Metal Oxide Semiconductor Switched Capacitor DC-DC Converter For Radio Frequency Micro Electro Mechanical Systems Switch Actuation

Achieving wireless connectivity in ever smaller, lower power portable devices with increasing number of features and better radio-frequency (RF) performance is becoming difficult to fulfill through existing RF front-end technology. RF micro-electro-mechanical systems (MEMS) switch technology, which has significantly better RF characteristics than conventional technology and has near-zero power consumption, is one of the emerging solutions for next generation RF front-ends. However, to achieve satisfactory RF MEMS device performance, it is often necessary to have an actuating circuitry to generate high direct current (DC) voltages for device actuation with low power consumption. In this study, the authors present an RF MEMS switch controller based on a switched-capacitor (SC) DC-DC converter in a 0.35 μm CMOS technology. In this design, novel design techniques for a higher output voltage and lower power consumption in a smaller die area are proposed. The authors demonstrate the design of the high-voltage (HV) SC DC-DC converter by using low-voltage transistors and address reliability issues in the design. Through the proposed design techniques, the SC DC-DC converter achieves more than 25% higher boosted voltage compared to converters that use HV transistors. The proposed design provides 40% power reduction through the charge recycling circuit. Moreover, the SC DC-DC converter achieves 45% smaller than the area of the conventional converter

Speedy Derivative-Corrective Mass Spring Algorithm For Adaptive Impedance Matching Networks

Adaptive impedance matching algorithms are used to preserve the link quality of mobile phones, under fluctuating user conditions. It is highly desirable to reduce the search time for minimising the risk of data loss during the impedance tuning process. Presented is a novel technique to reduce the search time by more than an order of magnitude by exploiting the relationships among the mass spring's coefficient values derived from the matching network parameters, thereby significantly reducing the convergence time of the algorithm

Dopant Profile Extraction by Inverse Modeling of Scanning Capacitance Microscopy Using Peak dC/dV

Scanning capacitance microscopy (SCM) has proven to be successful for junction delineation. However quantitative dopant profile extraction by SCM still remains a difficult challenge, due to limited understanding of relevant physics especially at p-n junction, as well as difficulties to accurately quantify all parameters in modeling. In this paper we present a new procedure, the use of peak dC/dV at every spatial point, for dopant profile extraction. The advantage of such a technique is twofold. First it eliminates problems encountered using a fixed dc bias such as contrast reversal. Second, it also excludes the need to model interface traps. This is because the peak dC/dV value is independent of the presence of interface traps, as demonstrated in our experimental results. Furthermore, based on our understanding of the influence of mobility degradation at p-n junction, we propose that low surface mobility model should be used in simulation so that only the accumulation-to-depletion dC/dV is extracted

Cost-effectiveness of Dermabond versus sutures for lacerated wound closure: A randomised controlled trial

1. For management of simple lacerated wounds, tissue adhesive (Dermabond) achieved more positive outcomes but incurred higher cost, compared with standard sutures. 2. Dermabond may be more cost-effective than standard sutures from a societal viewpoint. 3. Use of sutures required more nursing time and additional costs from subsequent dressing, whereas use of Dermabond incurred higher equipment costs. 4. Dermabond achieved better appearance outcome and patient satisfaction, compared with sutures. 5. Pain levels were not significantly different in patients treated with Dermabond or sutures

Mixed Spatial and Movement Representations in the Primate Posterior Parietal Cortex

The posterior parietal cortex (PPC) of humans and non-human primates plays a key role in the sensory and motor transformations required to guide motor actions to objects of interest in the environment. Despite decades of research, the anatomical and functional organization of this region is still a matter of contention. It is generally accepted that specialized parietal subregions and their functional counterparts in the frontal cortex participate in distinct segregated networks related to eye, arm and hand movements. However, experimental evidence obtained primarily from single neuron recording studies in non-human primates has demonstrated a rich mixing of signals processed by parietal neurons, calling into question ideas for a strict functional specialization. Here, we present a brief account of this line of research together with the basic trends in the anatomical connectivity patterns of the parietal subregions. We review, the evidence related to the functional communication between subregions of the PPC and describe progress towards using parietal neuron activity in neuroprosthetic applications. Recent literature suggests a role for the PPC not as a constellation of specialized functional subdomains, but as a dynamic network of sensorimotor loci that combine multiple signals and work in concert to guide motor behavior

Jet quenching and direct photon production

Jet quenching effect has been investigated in the direct photon production, based on a realistic data-constrained (3+1) dimensional hydrodynamic description of the expanding hot and dense matter, a reasonable treatment of the propagation of partons and their energy loss in the fluid, and a systematic study of the main sources of direct photons. Our resultant \pt spectra agree with recent PHENIX data in a broad \pt range. Parton energy loss in the plasma eventually effect significantly direct photon production from fragmentation and jet photon conversion, similar to hadron suppression in central heavy ion collisions. But this only causes about 40% decrease in the total production of direct photons, due to the mixture with other direct photon sources.Comment: 6 pages and 3 figures, To appear in the proceedings of the International Conference on Strangeness in Quark matter (SQM2008), Beijing, China, Oct 6-10, 200