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Thom Proven
No abstract text is available yet for this article.
January 2017: British Journal of Psychiatry: the Journal of Mental Science
Miquel Montero, Javier Villarroel
In this paper we consider a particular version of the random walk with restarts: random reset events which suddenly bring the system to the starting value. We analyze its relevant statistical properties, like the transition probability, and show how an equilibrium state appears. Formulas for the first-passage time, high-water marks, and other extreme statistics are also derived; we consider counting problems naturally associated with the system. Finally we indicate feasible generalizations useful for interpreting different physical effects...
September 2016: Physical Review. E
N J Fitch, M R Tarbutt
We explore a technique for decelerating molecules using a static magnetic field and optical pumping. Molecules travel through a spatially varying magnetic field and are repeatedly pumped into a weak-field seeking state as they move towards each strong field region, and into a strong-field seeking state as they move towards weak field. The method is time-independent and so is suitable for decelerating both pulsed and continuous molecular beams. By using guiding magnets at each weak field region, the beam can be simultaneously guided and decelerated...
November 18, 2016: Chemphyschem: a European Journal of Chemical Physics and Physical Chemistry
Andreas Dechant, Shalom Tzvi Shafier, David A Kessler, Eli Barkai
The Boltzmann-Gibbs density, a central result of equilibrium statistical mechanics, relates the energy of a system in contact with a thermal bath to its equilibrium statistics. This relation is lost for nonthermal systems such as cold atoms in optical lattices, where the heat bath is replaced with the laser beams of the lattice. We investigate in detail the stationary phase-space probability for Sisyphus cooling under harmonic confinement. In particular, we elucidate whether the total energy of the system still describes its stationary state statistics...
August 2016: Physical Review. E
M J Gullans, J Stehlik, Y-Y Liu, C Eichler, J R Petta, J M Taylor
We investigate the nonclassical states of light that emerge in a microwave resonator coupled to a periodically driven electron in a nanowire double quantum dot (DQD). Under certain drive configurations, we find that the resonator approaches a thermal state at the temperature of the surrounding substrate with a chemical potential given by a harmonic of the drive frequency. Away from these thermal regions we find regions of gain and loss, where the system can lase, or regions where the DQD acts as a single-photon source...
July 29, 2016: Physical Review Letters
Gimo M Daniel, Adrian Lv Davis, Clarke H Scholtz
Descriptions are provided for three new shade-associated species in the dung beetle genus, Sisyphus Latreille, 1807: Sisyphus umbraphilus sp. nov., Sisyphus oralensis sp. nov., and Sisyphus neobornemisszanus sp. nov. All three species are illustrated by photographs of habitus, diagnostic features, and male aedeagi. A map is provided showing their geographical distributions.
August 2, 2016: Zootaxa
Yuriy V Pershin, Sergey N Shevchenko, Franco Nori
Frequency generators are widely used in electronics. Here, we report the design and experimental realization of a memristive frequency generator employing a unique combination of only digital logic gates, a single-supply voltage and a realistic thresholdtype memristive device. In our circuit, the oscillator frequency and duty cycle are defined by the switching characteristics of the memristive device and external resistors. We demonstrate the circuit operation both experimentally, using a memristor emulator, and theoretically, using a model memristive device with threshold...
2016: Scientific Reports
Alexander Prehn, Martin Ibrügger, Rosa Glöckner, Gerhard Rempe, Martin Zeppenfeld
We demonstrate direct cooling of gaseous formaldehyde (H2CO) to the microkelvin regime. Our approach, optoelectrical Sisyphus cooling, provides a simple dissipative cooling method applicable to electrically trapped dipolar molecules. By reducing the temperature by 3 orders of magnitude and increasing the phase-space density by a factor of ∼10(4), we generate an ensemble of 3×10(5) molecules with a temperature of about 420  μK, populating a single rotational state with more than 80% purity.
February 12, 2016: Physical Review Letters
Sunil Vyas, Yuichi Kozawa, Yoko Miyamoto
We present a detailed theoretical analysis of the formation of standing waves using cylindrically polarized vector Laguerre-Gaussian (LG) beams. It is shown that complex interplay between the radial and azimuthal polarization state can be used to realize different kinds of polarization gradients with cylindrically symmetric polarization distribution. Expressions for four different cases are presented and local dynamics of spatial polarization distribution is studied. We show cylindrically symmetric Sisyphus and corkscrew type polarization gradients can be obtained from vector LG beams...
December 28, 2015: Optics Express
Marvin A Konstam, Jenica Upshaw
No abstract text is available yet for this article.
January 2016: JACC. Heart Failure
Andreas Dechant, David A Kessler, Eli Barkai
We investigate the semiclassical phase-space probability distribution P(x,p) of cold atoms in a Sisyphus cooling lattice with an additional harmonic confinement. We pose the question of whether this nonequilibrium steady state satisfies the equivalence of energy and probability. This equivalence is the foundation of Boltzmann-Gibbs and generalized thermostatic statistics, and a prerequisite for the description in terms of a temperature. At large energies, P(x,p) depends only on the Hamiltonian H(x,p) and the answer to the question is yes...
October 23, 2015: Physical Review Letters
Pauline Yzombard, Mehdi Hamamda, Sebastian Gerber, Michael Doser, Daniel Comparat
We propose a scheme for laser cooling of negatively charged molecules. We briefly summarize the requirements for such laser cooling and we identify a number of potential candidates. A detailed computation study with C_{2}^{-}, the most studied molecular anion, is carried out. Simulations of 3D laser cooling in a gas phase show that this molecule could be cooled down to below 1 mK in only a few tens of milliseconds, using standard lasers. Sisyphus cooling, where no photodetachment process is present, as well as Doppler laser cooling of trapped C_{2}^{-}, are also simulated...
May 29, 2015: Physical Review Letters
Netanel Hazut, Shlomi Medalion, David A Kessler, Eli Barkai
In this article we generalize the classical Edgeworth expansion for the probability density function (PDF) of sums of a finite number of symmetric independent identically distributed random variables with a finite variance to PDFs with a diverging variance, which converge to a Lévy α-stable density function. Our correction may be written by means of a series of fractional derivatives of the Lévy and the conjugate Lévy PDFs. This series expansion is general and applies also to the Gaussian regime. To describe the terms in the series expansion, we introduce a new family of special functions and briefly discuss their properties...
May 2015: Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
Shamez N Ladhani, Mary E Ramsay
No abstract text is available yet for this article.
September 1, 2015: Clinical Infectious Diseases: An Official Publication of the Infectious Diseases Society of America
Leonid Frantsevich, Stanislav Gorb, Vladimir Radchenko, Dmytro Gladun
Some flying beetles have peculiar functional properties of their elytra, if compared with the vast majority of beetles. A "typical" beetle covers its pterothorax and the abdomen from above with closed elytra and links closed elytra together along the sutural edges. In the open state during flight, the sutural edges diverge much more than by 90°. Several beetles of unrelated taxa spread wings through lateral incisions on the elytra and turn the elytron during opening about 10-12° (Cetoniini, Scarabaeus, Gymnopleurus) or elevate their elytra without partition (Sisyphus, Tragocerus)...
March 2015: Arthropod Structure & Development
Mauricio Baum, Edilene Alcântara de Castro
No abstract text is available yet for this article.
July 2014: Revista da Sociedade Brasileira de Medicina Tropical
Kaare Mikkelsen, Alberto Imparato, Alessandro Torcini
The collective dynamics of excitatory pulse coupled neurons with spike-timing dependent plasticity is studied. The introduction of spike-timing dependent plasticity induces persistent irregular oscillations between strongly and weakly synchronized states, reminiscent of brain activity during slow-wave sleep. We explain the oscillations by a mechanism, the Sisyphus Effect, caused by a continuous feedback between the synaptic adjustments and the coherence in the neural firing. Due to this effect, the synaptic weights have oscillating equilibrium values, and this prevents the system from relaxing into a stationary macroscopic state...
May 17, 2013: Physical Review Letters
Kaare Mikkelsen, Alberto Imparato, Alessandro Torcini
The collective dynamics of excitatory pulse-coupled neural networks with spike-timing-dependent plasticity (STDP) is studied. Depending on the model parameters stationary states characterized by high or low synchronization can be observed. In particular, at the transition between these two regimes, persistent irregular low frequency oscillations between strongly and weakly synchronized states are observable, which can be identified as infraslow oscillations with frequencies ≃0.02-0.03 Hz. Their emergence can be explained in terms of the Sisyphus effect, a mechanism caused by a continuous feedback between the evolution of the coherent population activity and of the average synaptic weight...
June 2014: Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
M Roberts, E Lamont
The phenomenon of suicide is one of the primary concerns for mental health professions. The health-care literature is dominated by discussions that focus variously on local and national suicide prevention policies, on the assessment of those individuals judged to be at risk of committing suicide as well as the appropriateness and efficacy of interventions for those who express suicidal ideation and display suicidal behaviours. What appear less frequently in the literature, however, are critical analyses of the concept of suicide and, in particular, critical reflections on the manner in which the concept of suicide has been, and continues to be, understood or 'framed'...
December 2014: Journal of Psychiatric and Mental Health Nursing
Sang-Jin Sung
No abstract text is available yet for this article.
March 2014: Korean Journal of Orthodontics
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