Negative conductivity and anomalous screening in two-dimensional electron systems subjected to microwave radiation

A 2D electron system in a quantized magnetic field can be driven by microwave radiation into a non-equilibrium state with strong magnetooscillations of the dissipative conductivity. We demonstrate that in such system a negative conductivity can coexist with a positive diffusion coefficient. In a finite system, solution of coupled electrostatic and linear transport problems shows that the diffusion can stabilize a state with negative conductivity. Specifically, this happens when the system size is smaller than the absolute value of the non-equilibrium screening length that diverges at the point where the conductivity changes sign. We predict that a negative resistance can be measured in such a state. Further, for a non-zero difference between the work functions of two contacts, we explore the distribution of the electrostatic potential and of the electron density in the sample. We show that in the diffusion-stabilized regime of negative conductivity the system splits into two regions with opposite directions of electric field. This effect is a precursor of the domain structure that has been predicted to emerge spontaneously in the microwave-induced zero-resistance states.Comment: 8 pages, 4 figure

Minimally Invasive Urological Interventions in Outpatient Clinic on the Example of Prostate Biopsy

One of the main directions of improving medical care was the introduction of inpatient forms of medical care for patients who do not require round-the-clock supervision.Aim of the research: to prove the effectiveness and economic feasibility of minimally invasive procedures in outpatient conditions.Materials and methods. The study included 3524 patients in the period from 2010 to 2017, who underwent transrectal prostate biopsy on the basis of the Department of urology of polyclinic No. 195 of the Western district of Moscow. For comparison, the patients were taken, who underwent a biopsy of the prostate gland at the base hospital No. 31, No. 51, No. 17.Results. The average number of biopsies performed in hospital No. 31, No. 51 and No. 17 for the year amounted to 344 biopsies, and the average detectability of prostate cancer was 142 (41.3 %). The average number of biopsies per year in the urology department of the branch number 2 GP No. 195 amounted to 440.5, and the average detectability of prostate cancer – 152.8 (34.7 %). Thus, with comparable inpatient detection of prostate cancer in one large outpatient urology center, an average of 28 % more biopsies are performed (440.5 versus 344) than in 3 hospitals over a comparable period of time.Conclusions. Inpatient technologies can reduce the burden on hospitals. The development of hospital-replacing forms is determined by the need of the population and for efficient use of financial and technical resources of health care

An experimental test of the Jarzynski equality in a mechanical experiment

We have experimentally checked the Jarzynski equality and the Crooks relation on the thermal fluctuations of a macroscopic mechanical oscillator in contact with a heat reservoir. We found that, independently of the time scale and amplitude of the driving force, both relations are satisfied. These results give credit, at least in the case of Gaussian fluctuations, to the use of these relations in biological and chemical systems to estimate the free energy difference between two equilibrium states. An alternative method to estimate of the free nergy difference in isothermal process is proposed too.Comment: submitted to Europhysics Letter

Tunable photonic band gaps with coherently driven atoms in optical lattices

Optical lattice loaded with cold atoms can exhibit a tunable photonic band gap for a weak probe field under the conditions of electromagnetically induced transparency. This system possesses a number of advantageous properties, including reduced relaxation of Raman coherence and the associated probe absorption, and simultaneous enhancement of the index modulation and the resulting reflectivity of the medium. This flexible system has a potential to serve as a testbed of various designs for the linear and nonlinear photonic band gap materials at a very low light level and can be employed for realizing deterministic entanglement between weak quantum fields

Symmetric photon-photon coupling by atoms with Zeeman-split sublevels

We propose a simple scheme for highly efficient nonlinear interaction between two weak optical fields. The scheme is based on the attainment of electromagnetically induced transparency simultaneously for both fields via transitions between magnetically split F=1 atomic sublevels, in the presence of two driving fields. Thereby, equal slow group velocities and symmetric cross-coupling of the weak fields over long distances are achieved. By simply tuning the fields, this scheme can either yield giant cross-phase modulation or ultrasensitive two-photon switching.Comment: Modified scheme, 4 pages, 1 figur

Giant nonlinearity and entanglement of single photons in photonic bandgap structures

Giantly enhanced cross-phase modulation with suppressed spectral broadening is predicted between optically-induced dark-state polaritons whose propagation is strongly affected by photonic bandgaps of spatially periodic media with multilevel dopants. This mechanism is shown to be capable of fully entangling two single-photon pulses with high fidelity.Comment: 7 pages, 1 figur

Towards deterministic optical quantum computation with coherently driven atomic ensembles

Scalable and efficient quantum computation with photonic qubits requires (i) deterministic sources of single-photons, (ii) giant nonlinearities capable of entangling pairs of photons, and (iii) reliable single-photon detectors. In addition, an optical quantum computer would need a robust reversible photon storage devise. Here we discuss several related techniques, based on the coherent manipulation of atomic ensembles in the regime of electromagnetically induced transparency, that are capable of implementing all of the above prerequisites for deterministic optical quantum computation with single photons.Comment: 11 pages, 7 figure

Ovarian hyperstemulation syndrome as a private case of iatrogenic capillary leak syndrome

Idiopathic capillary leak syndrome was first described in 1960 and later received its name in honor of the discoverer - Clarkson's Disease. However, in the past two decades, more cases have been reported than in the previous 35 years, most likely due to improved recognition, the widespread use of assisted reproductive technologies in the treatment of infertility and the emergence of targer therapy - monoclonal antibodies for the treatment of cancer and autoimmune diseases. Except for Clarkson's disease, capillary leak syndrome can occur in engraftment syndrome, differentiation syndrome after bone marrow transplantation, ovarian hyperstimulation syndrome, hemophagocytic lymphohistiocytosis, viral infections, mostly hemorrhagic fevers, some autoimmune diseases, administration of recombinant interleukins, cytostatics, some monoclonal antibodies including treatment with the latest anticancer drugs - immune checkpoint inhibitors, snakebite envenomation, and ricin poisoning. This syndrome is characterized by a sharp increase in vascular permeability for fluid and protein molecules that leads to the loss of fluid into the interstitium, and presents with acute onset of severe edema, often asymmetric, hypotension, polyserositis, hemoconcentration and low blood protein level. In assisted reproductive technology programs, the introduction of gonadotropins results in an increase in estradiol levels, which leads to the development of immunopathological process, accompanied by leukocyte infiltration of blood vessels and secondary hypercytokinemia. Subsequently, the secondary «wave» of cytokines and vasoactive substances secreted in response to the introduction of human chorionic gonadotropin as an ovulation trigger, leads to disruption of interendothelial contacts and the development of ovarian hyperstimulation syndrome. It is necessary to conduct a further study of the pathogenesis of capillary leak syndrome, in order to develop promising methods for the prevention and correction of ovarian hyperstimulation syndrome in assisted reproductive technology programs

Dynamical Casimir Effect in a one-dimensional uniformly contracting cavity

We consider particle creation (the Dynamical Casimir effect) in a uniformly contracting ideal one-dimensional cavity non-perturbatively. The exact expression for the energy spectrum of created particles is obtained and its dependence on parameters of the problem is discussed. Unexpectedly, the number of created particles depends on the duration of the cavity contracting non-monotonously. This is explained by quantum interference of the events of particle creation which are taking place only at the moments of acceleration and deceleration of a boundary, while stable particle states exist (and thus no particles are created) at the time of contracting.Comment: 13 pages, 4 figure

3D Oscillator and Coulomb Systems reduced from Kahler spaces

We define the oscillator and Coulomb systems on four-dimensional spaces with U(2)-invariant Kahler metric and perform their Hamiltonian reduction to the three-dimensional oscillator and Coulomb systems specified by the presence of Dirac monopoles. We find the Kahler spaces with conic singularity, where the oscillator and Coulomb systems on three-dimensional sphere and two-sheet hyperboloid are originated. Then we construct the superintegrable oscillator system on three-dimensional sphere and hyperboloid, coupled to monopole, and find their four-dimensional origins. In the latter case the metric of configuration space is non-Kahler one. Finally, we extend these results to the family of Kahler spaces with conic singularities.Comment: To the memory of Professor Valery Ter-Antonyan, 11 page