NLO predictions for a lepton, missing transverse momentum and dijets at the Tevatron

n this letter we investigate the various processes that can contribute to a final state consisting of a lepton, missing transverse momentum and two jets at Next to Leading Order (NLO) at the Tevatron. In particular we consider the production of W/Z + 2 jets, diboson pairs, single top and the tt process with both fully leptonic and semi-leptonic decays. We present distributions for the invariant mass of the dijet system and normalisations of the various processes, accurate to NLO.Comment: 4 pages, 5 figure

FBG-based fibre-optic current sensors for power systems protection : laboratory evaluation

Conventional differential current unit protection schemes rely on a pair of electronic protection relays that measure current phasors separately at the boundaries of the protected zone. The scheme requires a separate, often optical, communications channel for the sharing of measurement information to enable the timely identification of and reaction to internal faults. The high voltage environment that the transducers must operate in poses a number of engineering problems stemming from the need for electrical isolation and requirement for transformation of high primary system current magnitudes. Additionally, when either the number of relays or distance between relays is increased, timing problems can arise due to the limited bandwidth, speed and changeable latencies of the communication channels and the increased computation requirements. Fibre-optical sensor systems are maturing as a technology and offer a number of advantages over conventional electronic sensor regimes, including the possession of inherent electrical isolation, chemical inertness, immunity to electromagnetic interference, and their small size and serial multiplexing capability. Fibre sensor systems are therefore experiencing increased uptake in industries that operate in harsh environments, such as oil and gas, or where specific requirements such as large step-out distances or resistance to radiation prohibit the use of electronic sensors. The Advanced Sensors Team within the Institute for Energy and Environment has developed fibre-optic point sensors for voltage and electrical current, based on fibre Bragg grating (FBG) technology, that have been applied successfully to power systems diagnostics. With the photonic systems capability to interrogate up to 100 km from source at kHz sample rates with up to 30 sensors in series, it is possible and highly desirable to adapt this technology for use in power systems protection, where immediate applications in unit and distance protection are clear. In this paper, the application of the FBG-based hybrid current sensor system to power systems protection is presented for the first time. Experimental tests of the response of an optical unit protection system to a range of internal and external fault scenarios are also reported. Secondary current inputs to the system are modelled using ATP and injected into the prototype test system via an APTS3 (Advanced Protection Testing System) unit. Fibre sensors, separated optically by 24 km of fibre, provide all measurement information via a single interrogation system situated at one end of the protected zone. Experimental results confirm high performance of the optical unit protection both in terms of sensitivity to internal faults and stability under external fault conditions. Therefore, the systems ability to overcome problems experienced in electronic relaying systems using conventional current sensing technologies is demonstrated. No separate communications channel is required in this configuration, with fault algorithms being deployed only at one location that need not be close to the protected zone. The fibre-optic current sensor systems capacity for long-distance interrogation and high sensor count qualify it for further applications in more complex protection schemes, or over larger distances, where a single fibre could form the basis of highly novel distributed protection schemes. This potential will also be discussed in detail in the paper

Inertia emulation control of VSC-HVDC transmission system

The increasing penetration of power electronics interfaced renewable generation (e.g. offshore wind) has been leading to a reduction in conventional synchronous-machine based generation. Most converter-interfaced energy sources do not contribute to the overall power system inertia; and therefore cannot support the system during system transients and disturbances. It is therefore desirable that voltage-source-converter (VSC) based high voltage direct current (HVDC) interfaces, which play an important role in delivery of renewable power to AC systems, could contribute a virtual inertia and provide AC grid frequency support. In this paper, an inertia emulation control (IEC) system is proposed that allows VSC-HVDC system to perform an inertial response in a similar fashion to synchronous machines (SM), by exercising the electro-static energy stored in DC shunt capacitors of the HVDC system. The proposed IEC scheme has been implemented in simulations and its performance is evaluated using Matlab/Simulink

Video Game Engagement And Pathology: Relationships Between Gaming Habits And Gaming Experience, Psychopathology, And Personality Variables

With the rise in video game play, many experts have become concerned about negative consequences from game play, such as aggression, decreased academic performance, and even addiction. It has been very difficult to establish criteria for video game addiction or even to distinguish addicted gamers from recreational gamers. This relates to considerable conceptual overlap between the concepts of addiction and that of engagement or flow. Using multiple online questionnaires, this thesis examines the relationships between video game play habits over the life span, acute psychopathology, personality factors, and positive outcomes. Results indicate that the experience of flow during game play may serve as a critical predictor of gaming pathology and that flow should be included whenever trying to study and characterize gaming pathology. Results also indicate that no single factor predicts gaming pathology. Rather, an individual\u27s gaming history, gaming experience, personality factors, and psychopathology all uniquely influence the possibility of gaming pathology. Also, there were significant differences between males and females for predictors of gaming pathology. For example, depressive symptoms were strongly predictive of gaming pathology for males while anxious symptoms were more predictive of gaming pathology for females. Ultimately, the interaction of a variety of factors relating to flow, psychopathology, and personality factors are each likely to contribute to the development of gaming pathology

Variations In Video Game Play Habits And Beliefs Over Time

Psychological research about the consequences of playing video games has grown exponentially, correlating to the exponential growth of the video game industry. In the past decade, a major impetus has related to the concept of video game addiction, pathological gaming, or Internet Gaming Disorder. While the presence of this problem is widely accepted and there is growing knowledge about the factors contributing to its development and perpetuation, there is minimal research speaking to intervention. The primary purpose of the present study was to identify a potential pathway to educate members of the gaming community about pathological gaming, with the hope that some of these educated members would recognize their own struggles and seek help. Secondary to that purpose was the intention of identifying factors correlating with awareness of pathological gaming problems and influencing help-seeking behavior among pathological gamers. To pursue these goals, an online survey was made available to avid gamers (N=881) through reddit.com. The survey contained questions about demographic factors, video game play habits and history, pathological gaming, and mental health factors (anxiety, depression, stress, ADHD). Participants completed the survey, then were exposed to a three minute intervention period (wait period, neutral support group, pathological gaming support group, diagnostic awareness lecture) before being asked to again complete the pathological gaming questionnaire. Participants were invited to a one-month follow up to assess changes in pathological gaming awareness and any efforts to engage in help-seeking behavior. Results did not find significant main effects across intervention conditions for awareness of pathological gaming or pursuit of help-seeking behavior. However, nearly 20% of those participating in the one month follow up reported engaging in some form of help-seeking behavior. Tendencies to engage in help seeking behavior were best predicted by self-reported level of pathological gaming and inattentiveness. Thus, there is considerable benefit to increase awareness of pathological gaming and it is important to recognize that ADHD may be a critically impactful factor for increasing the risk of developing pathological gaming

Inertia emulation control strategy for VSC-HVDC transmission systems

There is concern that the levels of inertia in power systems may decrease in the future, due to increased levels of energy being provided from renewable sources, which typically have little or no inertia. Voltage source converters (VSC) used in high voltage direct current (HVDC) transmission applications are often deliberately controlled in order to de-couple transients to prevent propagation of instability between interconnected systems. However, this can deny much needed support during transients that would otherwise be available from system inertia provided by rotating plant

Dynamic removal of replication protein A by Dna2 facilitates primer cleavage during Okazaki fragment processing in Saccharomyces cerevisiae

Eukaryotic Okazaki fragments are initiated by an RNA/DNA primer, which is removed before the fragments are joined. Polymerase d displaces the primer into a flap for processing. Dna2 nuclease/helicase and flap endonuclease 1 (FEN1) are proposed to cleave the flap. The single-stranded DNA binding protein, replication protein A (RPA), governs cleavage activity. Flap-bound RPA inhibits FEN1. This necessitates cleavage by Dna2, which is stimulated by RPA. FEN1 then cuts the remaining RPA-free flap to create a nick for ligation. Cleavage by Dna2 requires that it enter the 5'-end and track down the flap. Since Dna2 cleaves the RPA-bound flap, we investigated the mechanism by which Dna2 accesses the protein-coated flap for cleavage. Using a nuclease-defective Dna2 mutant, we showed that just binding of Dna2 dissociates the flap-bound RPA. Facile dissociation is specific to substrates with a genuine flap, and will not occur with an RPA-coated single strand. We also compared the cleavage patterns of Dna2 with and without RPA to better define RPA stimulation of Dna2. Stimulation derived from removal of DNA folding in the flap. Apparently, coordinated with its dissociation, RPA relinquishes the flap to Dna2 for tracking in a way that does not allow flap structure to reform. We also found that RPA strand melting activity promotes excessive flap elongation, but it is suppressed by Dna2-promoted RPA dissociation. Overall, results indicate that Dna2 and RPA coordinate their functions for efficient flap cleavage and preparation for FEN1