41 research outputs found
Multi-lepton signals from the top-prime quark at the LHC
We analyze the collider signatures of models with a vector-like top-prime
quark and a massive color-octet boson. The top-prime quark mixes with the top
quark in the Standard Model, leading to richer final states than ones that are
investigated by experimental collaborations. We discuss the multi-lepton final
states, and show that they can provide increased sensitivity to models with a
top-prime quark and gluon-prime. Searches for new physics in high multiplicity
events are an important component of the LHC program and complementary to
analyses that have been performed.Comment: 7 pages, 4 figures, 2 table
TeV physics and the Planck scale
Supersymmetry is one of the best motivated possibilities for new physics at
the TeV scale. However, both concrete string constructions and phenomenological
considerations suggest the possibility that the physics at the TeV scale could
be more complicated than the Minimal Supersymmetric Standard Model (MSSM),
e.g., due to extended gauge symmetries, new vector-like supermultiplets with
non-standard SU(2)xU(1) assignments, and extended Higgs sectors. We briefly
comment on some of these possibilities, and discuss in more detail the class of
extensions of the MSSM involving an additional standard model singlet field.
The latter provides a solution to the problem, and allows significant
modifications of the MSSM in the Higgs and neutralino sectors, with important
consequences for collider physics, cold dark matter, and electroweak
baryogenesis.Comment: 17 pages, 5 figures. To appear in New Journal of Physic
Sports coaching and the law of negligence: implications for coaching practice
The ordinary principles of the law of negligence are applicable in the context of sport, including claims brought against volunteer and professional coaches. Adopting the perspective of the coach, this article intends to raise awareness of the emerging intersection between the law of negligence and sports coaching, by utilising an interdisciplinary analysis designed to better safeguard and reassure coaches mindful of legal liability. Detailed scrutiny of two cases concerning alleged negligent coaching, with complementary discussion of some of the ethical dilemmas facing modern coaches, reinforces the legal duty and obligation of all coaches to adopt objectively reasonable and justifiable coaching practices when interacting with athletes. Problematically, since research suggests that some coaching practice may be underpinned by âentrenched legitimacyâ and âuncritical inertiaâ, it is argued that coach education and training should place a greater emphasis on developing a coachâs awareness and understanding of the evolving legal context in which they discharge the duty of care incumbent upon them
Methods for classically simulating noisy networked quantum architectures
As research on building scalable quantum computers advances, it is important
to be able to certify their correctness. Due to the exponential hardness of
classically simulating quantum computation, straight-forward verification
through classical simulation fails. However, we can classically simulate small
scale quantum computations and hence we are able to test that devices behave as
expected in this domain. This constitutes the first step towards obtaining
confidence in the anticipated quantum-advantage when we extend to scales which
can no longer be simulated.
Realistic devices have restrictions due to their architecture and limitations
due to physical imperfections and noise. Here we extend the usual ideal
simulations by considering those effects. We provide a general methodology for
constructing realistic simulations emulating the physical system which will
both provide a benchmark for realistic devices, and guide experimental research
in the quest for quantum-advantage.
We exemplify our methodology by simulating a networked architecture and
corresponding noise-model; in particular that of the device developed in the
Networked Quantum Information Technologies Hub (NQIT). For our simulations we
use, with suitable modification, the classical simulator of of Bravyi and
Gosset. The specific problems considered belong to the class of Instantaneous
Quantum Polynomial-time (IQP) problems, a class believed to be hard for
classical computing devices, and to be a promising candidate for the first
demonstration of quantum-advantage. We first consider a subclass of IQP,
defined by Bermejo-Vega et al, involving two-dimensional dynamical quantum
simulators, before moving to more general instances of IQP, but which are still
restricted to the architecture of NQIT.Comment: 55 pages, 16 figure
Prevalence, Resistance Mechanisms, and Susceptibility of Multidrug-Resistant Bloodstream Isolates of Pseudomonas aeruginosaâż
Pseudomonas aeruginosa is an important pathogen commonly implicated in nosocomial infections. The occurrence of multidrug-resistant (MDR) P. aeruginosa strains is increasing worldwide and limiting our therapeutic options. The MDR phenotype can be mediated by a variety of resistance mechanisms, and the corresponding relative biofitness is not well established. We examined the prevalence, resistance mechanisms, and susceptibility of MDR P. aeruginosa isolates (resistant to â„3 classes of antipseudomonal agents [penicillins/cephalosporins, carbapenems, quinolones, and aminoglycosides]) obtained from a large, university-affiliated hospital. Among 235 nonrepeat bloodstream isolates screened between 2005 and 2007, 33 isolates (from 20 unique patients) were found to be MDR (crude prevalence rate, 14%). All isolates were resistant to carbapenems and quinolones, 91% were resistant to penicillins/cephalosporins, and 21% were resistant to the aminoglycosides. By using the first available isolate for each bacteremia episode (n = 18), 13 distinct clones were revealed by repetitive-element-based PCR. Western blotting revealed eight isolates (44%) to have MexB overexpression. Production of a carbapenemase (VIM-2) was found in one isolate, and mutations in gyrA (T83I) and parC (S87L) were commonly found. Growth rates of most MDR isolates were similar to that of the wild type, and two isolates (11%) were found to be hypermutable. All available isolates were susceptible to polymyxin B, and only one isolate was nonsusceptible to colistin (MIC, 3 mg/liter), but all isolates were nonsusceptible to doripenem (MIC, >2 mg/liter). Understanding and continuous monitoring of the prevalence and resistance mechanisms of MDR P. aeruginosa would enable us to formulate rational treatment strategies to combat nosocomial infections