Au-Ag template stripped pattern for scanning probe investigations of DNA arrays produced by Dip Pen Nanolithography

We report on DNA arrays produced by Dip Pen Nanolithography (DPN) on a novel Au-Ag micro patterned template stripped surface. DNA arrays have been investigated by atomic force microscopy (AFM) and scanning tunnelling microscopy (STM) showing that the patterned template stripped substrate enables easy retrieval of the DPN-functionalized zone with a standard optical microscope permitting a multi-instrument and multi-technique local detection and analysis. Moreover the smooth surface of the Au squares (abput 5-10 angstrom roughness) allows to be sensitive to the hybridization of the oligonucleotide array with label-free target DNA. Our Au-Ag substrates, combining the retrieving capabilities of the patterned surface with the smoothness of the template stripped technique, are candidates for the investigation of DPN nanostructures and for the development of label free detection methods for DNA nanoarrays based on the use of scanning probes.Comment: Langmuir (accepted

A Flux-weakening Strategy for Current-Regulated Surface-mounted Permanent-magnet Machine Drives

Permanent-magnet synchronous machines fed from current-regulated converters feature nearly ideal performance at low-to-moderate speeds. However, as rotor speed increases the back emf rises which results in loss of current regulation and decreased torque. In buried-magnet machine drives, flux weakening is often used to extend the speed range. This paper sets forth a flux-weakening control specifically designed for surface-mounted permanent-magnet machines which is simple and does not require knowledge of the machine or system parameters. The proposed method is demonstrated both experimentally and through the use of computer simulatio

Analysis of a Current-Regulated Brushless DC Drive

Current-regulated brushless DC machines are used in a wide variety of applications including robotics, actuators, electric vehicles, and ship propulsion systems. When conducting system analysis of this or any other type of drive, average-value reduced-order models are invaluable since they provide a means of rapidly predicting the electromechanical dynamics and are readily linearized for control system synthesis. In this paper, a highly accurate average-value reduced-order model of a hysteresis current-regulated brushless DC drive is set forth. In so doing it is demonstrated that the drive exhibits five distinct operating modes. The physical cause of each of these modes is explained and a mathematical model for each mode is set forth. The mathematical models are verified both experimentally and through the use of computer simulation. It has been found that the model set fourth herein is on the order of 300 times faster than a detailed computer simulation in calculating electromechanical transient

Transient and Dynamic Average-Value Modeling of Synchronous Machine Fed Load-Commutated Converters

A new average-value model of a synchronous machine fed load-commutated converter is set forth in which the stator dynamics are combined with the DC link dynamics. This model is shown to he extremely accurate in predicting system transients and in predicting frequency-domain characteristics such as the impedance looking into the synchronous machine fed load-commutated converter. The model is verified against a detailed computer simulation and against a hardware test system, thus providing a three-way comparison. The proposed model is shown to be much more accurate than models in which the stator dynamics are neglecte

Prototype ATLAS IBL Modules using the FE-I4A Front-End Readout Chip

The ATLAS Collaboration will upgrade its semiconductor pixel tracking detector with a new Insertable B-layer (IBL) between the existing pixel detector and the vacuum pipe of the Large Hadron Collider. The extreme operating conditions at this location have necessitated the development of new radiation hard pixel sensor technologies and a new front-end readout chip, called the FE-I4. Planar pixel sensors and 3D pixel sensors have been investigated to equip this new pixel layer, and prototype modules using the FE-I4A have been fabricated and characterized using 120 GeV pions at the CERN SPS and 4 GeV positrons at DESY, before and after module irradiation. Beam test results are presented, including charge collection efficiency, tracking efficiency and charge sharing.Comment: 45 pages, 30 figures, submitted to JINS

Search for the standard model Higgs boson in the H to ZZ to 2l 2nu channel in pp collisions at sqrt(s) = 7 TeV

A search for the standard model Higgs boson in the H to ZZ to 2l 2nu decay channel, where l = e or mu, in pp collisions at a center-of-mass energy of 7 TeV is presented. The data were collected at the LHC, with the CMS detector, and correspond to an integrated luminosity of 4.6 inverse femtobarns. No significant excess is observed above the background expectation, and upper limits are set on the Higgs boson production cross section. The presence of the standard model Higgs boson with a mass in the 270-440 GeV range is excluded at 95% confidence level.Comment: Submitted to JHE

Dynamics and Regulation of RecA Polymerization and De-Polymerization on Double-Stranded DNA

10.1371/journal.pone.0066712PLoS ONE86

Combined search for the quarks of a sequential fourth generation

Results are presented from a search for a fourth generation of quarks produced singly or in pairs in a data set corresponding to an integrated luminosity of 5 inverse femtobarns recorded by the CMS experiment at the LHC in 2011. A novel strategy has been developed for a combined search for quarks of the up and down type in decay channels with at least one isolated muon or electron. Limits on the mass of the fourth-generation quarks and the relevant Cabibbo-Kobayashi-Maskawa matrix elements are derived in the context of a simple extension of the standard model with a sequential fourth generation of fermions. The existence of mass-degenerate fourth-generation quarks with masses below 685 GeV is excluded at 95% confidence level for minimal off-diagonal mixing between the third- and the fourth-generation quarks. With a mass difference of 25 GeV between the quark masses, the obtained limit on the masses of the fourth-generation quarks shifts by about +/- 20 GeV. These results significantly reduce the allowed parameter space for a fourth generation of fermions.Comment: Replaced with published version. Added journal reference and DO

Performance of the CMS Cathode Strip Chambers with Cosmic Rays

The Cathode Strip Chambers (CSCs) constitute the primary muon tracking device in the CMS endcaps. Their performance has been evaluated using data taken during a cosmic ray run in fall 2008. Measured noise levels are low, with the number of noisy channels well below 1%. Coordinate resolution was measured for all types of chambers, and fall in the range 47 microns to 243 microns. The efficiencies for local charged track triggers, for hit and for segments reconstruction were measured, and are above 99%. The timing resolution per layer is approximately 5 ns

A Voltage Control Strategy for Current-Regulated PWM Inverters

Alternative voltage control strategies for current-regulated PWM inverters are analyzed, including previously established feedforward and feedforward/feedback controllers and a newly proposed decoupling feedback control strategy. The steady-state and dynamic characteristics of each of these control methods are illustrated and compared for a selected inverter design. It is shown that the feedforward controller exhibits steady-state error and an undesirable overshoot of the output voltages during startup. The addition of a feedback loop eliminates the steady-state error and reduces the overshoot; however, the natural response is underdamped regardless of the choice of feedback gains. A decoupling feedback control strategy that eliminates the disadvantages of the feedforward and feedforward/feedback controllers is described. Using the decoupling feedback controller, it is possible to eliminate the steady-state error and place the closed-loop poles wherever desired. Moreover, if the closed-loop poles are selected appropriately, it is possible to eliminate the overshoot of the output voltages during startup transients. © 1996 IEEE