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Cyclotron radiation emission spectroscopy (CRES) is a modern approach for determining charged particle energies via high-precision frequency measurements of the emitted cyclotron radiation. For CRES experiments with gas within the fiducial volume, signal and noise dynamics can be modelled by a hidden Markov model. We introduce a novel application of the Viterbi algorithm in order to derive informational limits on the optimal detection of cyclotron radiation signals in this class of gas-filled CRES experiments, thereby providing concrete limits from which future reconstruction algorithms, as well as detector designs, can be constrained. The validity of the resultant decision rules is confirmed using both Monte Carlo and Project 8 data. [ABSTRACT FROM AUTHOR]

The cyclotron radiation emission spectroscopy (CRES) technique pioneered by Project 8 measures electromagnetic radiation from individual electrons gyrating in a background magnetic field to construct a highly precise energy spectrum for beta decay studies and other applications. The detector, magnetic trap geometry and electron dynamics give rise to a multitude of complex electron signal structures which carry information about distinguishing physical traits. With machine learning models, we develop a scheme based on these traits to analyze and classify CRES signals. Proper understanding and use of these traits will be instrumental to improve cyclotron frequency reconstruction and boost the potential of Project 8 to achieve world-leading sensitivity on the tritium endpoint measurement in the future. [ABSTRACT FROM AUTHOR]

The Locust simulation package is a new C++ software tool developed to simulate the measurement of time-varying electromagnetic fields using RF detection techniques. Modularity and flexibility allow for arbitrary input signals, while concurrently supporting tight integration with physics-based simulations as input. External signals driven by the Kassiopeia particle tracking package are discussed, demonstrating conditional feedback between Locust and Kassiopeia during software execution. An application of the simulation to the Project 8 experiment is described. Locust is publicly available at https://github.com/project8/locust_mc. [ABSTRACT FROM AUTHOR]

A comparative study of the relative stability of subphthalocyanine metallosupramolecular capsules bearing different metals and ligands has been carried out by electrospray ionization quadrupole time-of-flight tandem mass spectrometry experiments. The results highlight the trends in the strength of metal-nitrogen bonds as well as the ' trans effect' of certain ligands. Copyright © 2013 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

A theoretical investigation on the redox processes in the subphthalocyanines (SubPcs) was performed. Singly and doubly oxidative and reductive transformations were considered. The full geometry optimization of the participating molecules showed that the cone shape arrangement of the SubPc is preserved in their ionic derivatives even when two electrons are either donated or subtracted from the molecule. The biggest geometric changes under electron exchange processes were calculated for the B—Cl bond distance. The electronic density distribution over all the products remains almost invariable with respect to the neutral molecule. Our calculations on the neutral and charged SubPcs demonstrated that they behave as conjugated systems, their electronic parameters being correlatively altered by the redox electron exchange. Further, the electronic state of the macrocycle atoms also depends on an intense electronic flow among the macrocyclic skeleton and the surrounding (axial chlorine and peripheral hydrogen) atoms that is associated with the redox process. © 2002 Wiley Periodicals, Inc. Int J Quantum Chem, 2003 [ABSTRACT FROM AUTHOR]

We aim to estimate HIV prevalence and associated risk factors among street youth in Montreal, Canada. We conducted a one-year cross-sectional anonymous study in 1995. We recruited youth aged 13-25 years meeting specific criteria for itinerancy through the 20 major Montreal street youth agencies. Participation included a structured interview and provision of an oral specimen for HIV testing. Among the 909 subjects studied, 99.3% had been sexually active, 25.9% had exchanged sex for money, gifts, drugs, a place to sleep, or other things; 31.8% reported anal sex; and 36.4% reported having ever injected drugs. Overall, HIV prevalence was 1.9% (1.1% in girls and 2.2% in boys). Multivariate logistic regression showed that being over 20 years of age (adjusted odds ratio (AOR) 7.09), having injected drugs (AOR 4.48), having engaged in prostitution (AOR 3.32), and being born outside Canada (AOR 4.41) were all independently associated with HIV infection. [ABSTRACT FROM AUTHOR]

Background: To increase the performance capacity of a triathlete (Tri), a variety of adaptations are necessary. The heart is the central and the most important limiting factor. The structural heart adaptations in Tri have important repercussion on cardiac function. The left ventricular diastole shows specific characteristics that determine performance capacity. Methods: 40 male Tri were compared with 31 active male controls and with 112 patients with ischemic heart disease. All subjects underwent tissue Doppler and strain imaging. Results: The late diastolic filling period in Tri has specific characteristics. Tissue imaging demonstrated in Tri specific characteristics of both the late passive diastolic filling period and the early active diastolic relaxation period. The significant differences between the three groups concerning the strain values at the basal and the mid septum in the longitudinal axis by aortic valve closure and by mitral valve opening were extremely striking. The values of the end-diastolic strain by the end of the a-wave: negative in Tri, near-zero in normal controls, and marked positive in coronary patients were fascinating ( ). Conclusions: The marked negative end-diastolic strain in Tri can be explained by an increased muscular tone after a rapid and almost complete early diastolic filling of the left ventricle. This increased muscular tone is caused by an increase in the sarcomere length and by an increase in the number of actin-myosin cross-bridge interactions. These specific systolic and especially supernormal diastolic properties of the left ventricle with an increased diastolic reserve, enhance the aerobic capacities, resulting in an increased performance capacity. [ABSTRACT FROM AUTHOR]

The beta decay of tritium in the form of molecular T2 is the basis of sensitive experiments to measure neutrino mass. The final-state electronic, vibrational, and rotational excitations modify the beta spectrum significantly and are obtained from theory. We report measurements of the branching ratios to specific ionization states for the isotopolog HT. Two earlier, concordant measurements gave branching ratios of HT to the bound HHe+ ion of 89.5% and 93.2%, in sharp disagreement with the theoretical prediction of 55%-57%, raising concerns about the theory's reliability in neutrino mass experiments. Our result, 56.5(6)%, is compatible with the theoretical expectation and disagrees strongly with the previous measurements. [ABSTRACT FROM AUTHOR]