Temperature Control of Electromigration to form Gold Nanogap Junctions

Controlled electromigration of gold nanowires of different cross-sectional areas to form nanogap junctions is studied using a feedback method. A linear correlation between the cross sectional area of the gold nanowires and the power dissipated in the junction during electromigration is observed, indicating that the feedback mechanism operates primarily by controlling the temperature of the junction during electromigration. We also show that the role of the external feedback circuit is to prevent thermal runaway; minimization of series resistance allows controlled electromigration to a significant range of junction resistances with a simple voltage ramp.Comment: 14 pages,5 figure

Jet Triggers and Dijet Mass

We propose single jet triggers for CMS and simulate an analysis of the dijet mass distribution based on these triggers. A full trigger table for single jets is developed, including thresholds and prescales at L1 and HLT. The evolution of the table with instantaneous luminosity is presented, and the rates expected from the trigger are estimated. We present an analysis of the QCD dijet mass distribution that would result from taking data with this trigger. For three different samples of data corresponding to 100 pb^-1, 1 fb^-1, and 10 fb^-1 we estimate the expected statistical and systematic uncertainty on the cross section versus dijet mass

CMS search plans and sensitivity to new physics with dijets

CMS will use dijets to search for physics beyond the standard model during early LHC running. The inclusive jet cross section as a function of jet transverse momentum, with 10 inverse picobarns of integrated luminosity, is sensitive to contact interactions beyond the reach of the Tevatron. The dijet mass distribution will be used to search for dijet resonances coming from new particles, for example an excited quark. Additional sensitivity to the existence of contact interactions or dijet resonances can be obtained by comparing dijet rates in two distinct pseudorapidity regions.Comment: 10 pages, 4 figures, accepted for publication in J. Phys. G: Nucl. Part. Phy

CMS Sensitivity to Dijet Resonances

We estimate CMS sensitivity to narrow resonances in the dijet final state. The generic signal shape and QCD background are presented as a function of dijet mass for jet pseudorapidity in the region abs(eta)<1. Statistical and systematic uncertainties are estimated for integrated luminosities of 100 pb^-1, 1 fb^-1, and 10 fb^-1 and a realistic trigger table including multiple thresholds and prescales for jets. The cross section for a dijet resonance that CMS can expect to discovery at 5 sigma significance or exclude at 95% confidence level is presented. We compare these cross section sensitivities with the expected cross section from models of excited quarks, axigluons, colorons, E6 diquarks, color octet technirhos, Wprime, Zprime, and Randall-Sundrum gravitons to determine the masses for which we expect to be able to discover or to exclude these models

CMS Sensitivity to Quark Contact Interactions using Dijets

We estimate CMS sensitivity to quark contact interactions in the dijet final state. The canonical model of a contact interaction among left-handed composite quarks changes the dijet angular distribution at high dijet mass. The dijet ratio variable introduced at the Tevatron is used as a simple measure of the angular distribution as a function of dijet mass. The contact interaction signal and QCD background are estimated for the dijet ratio as a function of dijet mass from 0.3 to 6.5 TeV. Statistical uncertainties are estimated for integrated luminosities of 100 pb^-1, 1 fb^-1, and 10 fb^-1 and a realistic trigger table including multiple thresholds and prescales for the single jet triggers. Systematic uncertainties on the dijet ratio are estimated and are found to be small. The chisquard between the background and the signal is estimated, including systematics, and is used to find CMS sensitivity to the contact interaction scale Lambda^+. For an integrated luminosity of 100 pb^-1, 1 fb^-1, and 10 fb^-1, CMS can expect to exclude at 95% CL a Lambda^+ value of 6.2, 10.4, and 14.8 TeV or discover at 5 sigma significance a Lambda^+ value of 4.7, 7.8 and 12.0 TeV, respectively

Nanotransfer Printing of Organic and Carbon Nanotube Thin-Film Transistors on Plastic Substrates

A printing process for high-resolution transfer of all components for organic electronic devices on plastic substrates has been developed and demonstrated for pentacene (Pn), poly (3-hexylthiophene) and carbon nanotube (CNT) thin-film transistors (TFTs). The nanotransfer printing process allows fabrication of an entire device without exposing any component to incompatible processes and with reduced need for special chemical preparation of transfer or device substrates. Devices on plastic substrates include a Pn TFT with a saturation, field-effect mobility of 0.09 cm^2 (Vs)^-1 and on/off ratio approximately 10^4 and a CNT TFT which exhibits ambipolar behavior and no hysteresis.Comment: to appear in Applied Physics Letter

Determining the origin of synchronous multifocal bladder cancer by exome sequencing

Background: Synchronous multifocal tumours are commonly observed in urothelial carcinomas of the bladder. The origin of these physically independent tumours has been proposed to occur by either intraluminal migration (clonal) or spontaneous transformation of multiple cells by carcinogens (field effect). It is unclear which model is correct, with several studies supporting both hypotheses. A potential cause of this uncertainty may be the small number of genetic mutations previously used to quantify the relationship between these tumours. Methods: To better understand the genetic lineage of these tumours we conducted exome sequencing of synchronous multifocal pTa urothelial bladder cancers at a high depth, using multiple samples from three patients. Results: Phylogenetic analysis of high confidence single nucleotide variants (SNV) demonstrated that the sequenced multifocal bladder cancers arose from a clonal origin in all three patients (bootstrap value 100 %). Interestingly, in two patients the most common type of tumour-associated SNVs were cytosine mutations of TpC*dinucleotides (Fisher's exact test p &lt; 10-41), likely caused by APOBEC-mediated deamination. Incorporating these results into our clonal model, we found that TpC*type mutations occurred 2-5× more often among SNVs on the ancestral branches than in the more recent private branches (p &lt; 10-4) suggesting that TpC*mutations largely occurred early in the development of the tumour. Conclusions: These results demonstrate that synchronous multifocal bladder cancers frequently arise from a clonal origin. Our data also suggests that APOBEC-mediated mutations occur early in the development of the tumour and may be a driver of tumourigenesis in non-muscle invasive urothelial bladder cancer. © 2015 Acar et al