275 research outputs found
Resonators coupled to voltage-biased Josephson junctions: From linear response to strongly driven nonlinear oscillations
Motivated by recent experiments, where a voltage biased Josephson junction is
placed in series with a resonator, the classical dynamics of the circuit is
studied in various domains of parameter space. This problem can be mapped onto
the dissipative motion of a single degree of freedom in a nonlinear
time-dependent potential, where in contrast to conventional settings the
nonlinearity appears in the driving while the static potential is purely
harmonic. For long times the system approaches steady states which are analyzed
in the underdamped regime over the full range of driving parameters including
the fundamental resonance as well as higher and sub-harmonics. Observables such
as the dc-Josephson current and the radiated microwave power give direct
information about the underlying dynamics covering phenomena as bifurcations,
irregular motion, up- and down conversion. Due to their tunability, present and
future set-ups provide versatile platforms to explore the changeover from
linear response to strongly nonlinear behavior in driven dissipative systems
under well defined conditions.Comment: 12 pages, 11 figure
Collective dynamics in optomechanical arrays
The emerging field of optomechanics seeks to explore the interaction between
nanomechanics and light. Recently, the exciting concept of optomechanical
crystals has been introduced, where defects in photonic crystal structures are
used to generate both localized optical and mechanical modes that interact with
each other. Here we start exploring the collective dynamics of arrays
consisting of many coupled optomechanical cells. We show that such
"optomechanical arrays" can display synchronization and that they can be
described by a modified Kuramoto model that allows to explain and predict most
of the features that will be observable in future experiments.Comment: 6 pages, 5 figure
Antibunched photons emitted by a dc-biased Josephson junction
We show experimentally that a dc biased Josephson junction in series with a high-enough-impedance microwave resonator emits antibunched photons. Our resonator is made of a simple microfabricated spiral coil that resonates at 4.4 GHz and reaches a 1.97kΩ characteristic impedance. The second order correlation function of the power leaking out of the resonator drops down to 0.3 at zero delay, which demonstrates the antibunching of the photons emitted by the circuit at a rate of 6×10^7 photons per second. Results are found in quantitative agreement with our theoretical predictions. This simple scheme could offer an efficient and bright single-photon source in the microwave domain
Interference through quantum dots
We discuss the effect of quantum interference on transport through a quantum
dot system. We introduce an indirect coherent coupling parameter alpha, which
provides constructive/destructive interference in the transport current
depending on its phase and the magnetic flux. We estimate the current through
the quantum dot system using the non-equilibrium Green's function method as
well as the master equation method in the sequential tunneling regime. The
visibility of the Aharonov-Bohm oscillation is evaluated. For a large inter-dot
Coulomb interaction, the current is strongly suppressed by the quantum
interference effect, while the current is restored by applying an oscillating
resonance field with the frequency of twice the inter-dot tunneling energy.Comment: 10 pages, 3 figure
Prevention and extinguishment of fires involving hypergolic propellants Final report
Halon 1301 system effectiveness in prevention and extinguishment of hypergolic propellant fire
Seed Priming: New Comprehensive Approaches for an Old Empirical Technique
Seed priming is a pre-sowing treatment which leads to a physiological state that enables seed to germinate more efficiently. The majority of seed treatments are based on seed imbibition allowing the seeds to go through the first reversible stage of germination but do not allow radical protrusion through the seed coat. Seeds keeping their desiccation tolerance are then dehydrated and can be stored until final sowing. During subsequent germination, primed seeds exhibit a faster and more synchronized germination and young seedlings are often more vigorous and resistant to abiotic stresses than seedlings obtained from unprimed seeds. Priming often involves soaking seed in predetermined amounts of water or limitation of the imbibition time. The imbibition rate could be somehow controlled by osmotic agents such as PEG and referred as osmopriming. Halopriming implies the use of specific salts while "hormopriming" relies on the use of plant growth regulators. Some physical treatments (UV, cold or heat,..) also provide germination improvement thus suggesting that priming effects are not necessarily related to seed imbibition. A better understanding of the metabolic events taking place during the priming treatment and the subsequent germination should help to use this simple and cheap technology in a more efficient way
Transport in metallic multi-island Coulomb blockade systems: A systematic perturbative expansion in the junction transparency
We study electronic transport through metallic multi-island Coulomb-blockade
systems. Based on a diagrammatic real-time approach, we develop a computer
algorithm that generates and calculates all transport contributions up to
second order in the tunnel-coupling strengths for arbitrary multi-island
systems. This comprises sequential and cotunneling, as well as terms
corresponding to a renormalization of charging energies and tunneling
conductances. Multi-island cotunneling processes with energy transfer between
different island are taken into account. To illustrate our approach we analyze
the current through an island in Coulomb blockade, that is electrostatically
coupled to a second island through which a large current is flowing. In this
regime both cotunneling processes involving one island only as well as
multi-island processes are important. The latter can be understood as
photon-assisted sequential tunneling in the blockaded island, where the photons
are provided by potential fluctuations due to sequential tunneling in the
second island. We compare results of our approach to a P(E)-theory for
photon-assisted tunneling in the weak coupling limit.Comment: 14 pages, 7 figures, published version; minor changes in Sec. IV
The Use of Neutrophil-to-Lymphocyte Ratio, Monocyte-to-Lymphocyte Ratio and Platelets-to-Lymphocyte Ratio in the Assessment of the Risk of Conversion and Complications After Cholecystectomy Performed Due to Symptomatic Cholelithiasis
Bartosz Molasy,1,2 Mateusz Frydrych,2 Aldona Kubala-Kukuś,3 Stanisław Głuszek1 1Collegium Medicum, The Jan Kochanowski University, Kielce, Poland; 2Department of General Surgery, St Alexander Hospital, Kielce, Poland; 3Institute of Physics, Jan Kochanowski University, Kielce, PolandCorrespondence: Bartosz Molasy, Department of General Surgery, St Alexander Hospital, Kościuszki 25, Kielce, 25-313, Poland, Tel +48 41 341 78 20, Email [email protected]: Laparoscopic cholecystectomy is quite a safe procedure, as only about 2% of cases result in clinically significant postoperative complications. The occurrence of conversion and postoperative complications is associated with prolonged hospitalization and higher perioperative mortality. Some parameters assessed in preoperative laboratory tests are used to predict the risk of conversion and clinically significant postoperative complications. The aim of this study was to evaluate the usefulness of preoperative neutrophil-to-lymphocyte ratio (NLR), monocyte-to-lymphocyte ratio (MLR) and platelets-to-lymphocyte ratio (PLR) values in predicting the risk of conversion and complications in laparoscopic cholecystectomy performed due to symptomatic cholelithiasis.Patients and Methods: A retrospective analysis of patients operated on for symptomatic cholelithiasis was performed. The Results of preoperative laboratory tests were assessed – NLR, MLR and PLR. Their impact on early outcomes of surgical treatment was analyzed in the study population.Results: The analysis concerned 227 patients operated on for symptomatic cholelithiasis. The study group included 61 (26.9%) men and 166 (73.1%) women. As the NLR, MLR and PLR values increase, the length of hospitalization increases (rS 0.226, 0.247 and 0.181, respectively), as well as the risk of converting the procedure to an open method (p< 0.05). Moreover, with increasing NLR and MLR values, the grade of postoperative complications according to the Clavien-Dindo scale increases (p 0.0001 and 0.008, respectively). The grade of postoperative complications does not depend on the PLR value.Conclusion: The risk of conversion can be assessed based on preoperative NLR, MLR and PLR values in patients undergoing surgery for symptomatic cholelithiasis. Elevated preoperative NLR and MLR values are associated with a higher grade of postoperative complications in the Clavien-Dindo scale.Keywords: laparoscopic cholecystectomy, conversion, complications, neutrophil-to-lymphocyte ratio, monocyte-to-lymphocyte ratio, platelets-to-lymphocyte rati
Josephson photonics with a two-mode superconducting circuit
We analyze the quantum dynamics of two electromagnetic oscillators coupled in series to a voltage-biased Josephson junction. When the applied voltage leads to a Josephson frequency across the junction which matches the sum of the two mode frequencies, tunneling Cooper pairs excite photons in both modes simultaneously leading to far-from-equilibrium states. These states display highly nonclassical features including strong antibunching, violation of Cauchy-Schwartz inequalities, and number squeezing. We obtain approximate analytic results for both the regimes of low and high photon occupancies which are supported by a full numerical treatment. The impact of asymmetries between the two modes is explored, revealing a pronounced enhancement of number squeezing when the modes are damped at different rates
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