Undoing the effect of loss on quantum entanglement

Entanglement distillation is a process via which the strength and purity of quantum entanglement can be increased probabilistically. It is a key step in many quantum communication and computation protocols. In particular, entanglement distillation is a necessary component of the quantum repeater, a device which counters the degradation of entanglement that inevitably occurs due to losses in a communication line. Here we report an experiment on distilling the Einstein-Podolsky-Rosen (EPR) state of light, the workhorse of continuous-variable entanglement, using the technique of noiseless amplification. In contrast to previous implementations, the entanglement enhancement factor achievable by our technique is not fundamentally limited and permits recovering an EPR state with a macroscopic level of entanglement no matter how low the initial entanglement or how high the loss may be. In particular, we recover the original level of entanglement after one of the EPR modes has passed through a channel with a loss factor of 20. The level of entanglement in our distilled state is higher than that achievable by direct transmission of any state through a similar loss channel. This is a key bench-marking step towards the realization of a practical continuous-variable quantum repeater and other CV quantum protocols.Comment: 8 pages, 5 figure

Detection of antibodies to erythropoietin-based drugs: is it possible to create the universal test system?

Our aim was to compare different immobilized erythropoietin (EPO) preparations for their ability to detect anti-EPO IgG antibodies in blood sera of EPO-treated patients with ELISA technique. 294 serum samples of the patients treated with erythropoietin were analyzed. 127 serum samples of patients who did not receive recombinant human EPO (rhEPO) were studied for comparative analysis. ELISA assay was performed, and different rhEPO drugs were immobilized on the anti-EPO monoclonal antibody-coated plates. Horseradish peroxidase-conjugated mouse monoclonal antibodies to human IgG, IgG1, and IgG4 was used for detection. The following drugs were studied: recombinant human erythropoietin rhEPO-beta (Shandong Kexing Bioproducts), European standard of erythropoietin BRP 3, commercial drugs Aranesp (Amgen Europe B.V.), Mircera (F. Hoffmann-La Roche Ltd.), Eprex (Johnson & Johnson LLC), Eralfon (Pharmaceutical Company Sotex). The sensitivity of the method was expressed as a positivity index (IP). IP calculated as the ratio of OD from tested sera to OD at the cut-off levels. The latter was assumed as a mean OD±SD for serum samples from EPO-naive patients. The results were evaluated as positive with IP > 1.1, and negative at IP < 0.9. Results in the range of 0.9 ≤ IP < 1.1 were considered as unidentified. Among the 294 samples, 32 specimens were evaluated as positive or unidentified for total IgG anti-EPO antibodies. The unidentified samples were detected in 1.0-1.7% of all cases. IgG1 subclass antibodies were found in 50-56.3% of patients and IgG4 subclass antibodies, in 43.850% of the patients. Mann—Whitney test showed a significant difference between the test samples compared to control group for all the ELISA modifications (p = 0.001). The Kruskal—Wallis test did not show significant differences between the IP results obtained with any of five immobilized EPO drugs (p = 0.05). The correlation quotient of IP was in the range of 0.99-0.96 for total IgG and > 0.98 for two subclasses of antibodies. Linear regression coefficients were close to one, thus indicating absence of significant differences in the sensitivity of the compared methods. This study indicate the opportunity of using the similar test systems to determine anti-EPO antibodies in the patients treated with various rhEPO drugs. Therefore, it is possible to develop a universal commercial test system to this purpose

Parametric Generation of Second Sound by First Sound in Superfluid Helium

We report the first experimental observation of parametric generation of second sound (SS) by first sound (FS) in superfluid helium in a narrow temperature range in the vicinity of $T_\lambda$. The temperature dependence of the threshold FS amplitude is found to be in a good quantitative agreement with the theory suggested long time ago and corrected for a finite geometry. Strong amplitude fluctuations and two types of the SS spectra are observed above the bifurcation. The latter effect is quantitatively explained by the discreteness of the wave vector space and the strong temperature dependence of the SS dissipation length.Comment: 4 pages, 4 postscript figures, REVTE

Features of compiling metabolic correction programs for professional athletes and the possibility of their optimization using digital technologies

To compile a personalized program for correcting the metabolism of a professional athlete, it is necessary to take into account many factors, including age, gender, sports specialization, individual characteristics, the pathologies in the anamnesis, the stage of the athlete’s training cycle, etc. When drawing up such programs for athletes of sports national teams of the Russian Federation, a scheme for assessing the characteristics of the athlete’s body is used, the basis for which is information obtained during in-depth medical examinations of athletes conducted on the basis of clinics of the FMBA Russia. To improve the quality of personalized programs of metabolic correction in the future, it is possible to use professionally oriented reference intervals of laboratory blood parameters, as well as the results of genetic screening based on the strategy of complete exomic sequencing of the athlete’s genome. One of the ways to increase the efficiency of metabolic correction of professional athletes is the introduction of modern information technologies and the development of a modern information system based on them. The introduction of such an information system will increase the speed of primary processing of initial information about the health status of the athlete and the peculiarities of his metabolic processes, as well as partially automate the formation of individualized recommendations regarding the diet and hydratation, and the choice of metabolic correction at various stages of the sports season

Development and preclinical research of a product «Fit Tonus» for correction of a psychophysiological state and neuromuscular transfer in highly skilled athletes

Objective: development and tests of a specialized food stuff for correction of a psychophysiological state and neuromuscular transfer in highly skilled athletes. Materials and methods: objects of researches were: 2 prescriptions (in two dosages of 30 mkg/g and 60 mkg/g) of the developed specialized product of sports food for correction of a psychophysiological state and neuromuscular transfer in highly skilled athletes; 200 male rats of males of the Wistar line. Researches were conducted according to the official and standard techniques. Following physiological parameters were measured used during the study: arterial blood pressure, heart rate, body temperature, respiration rate, ECG; specialized tests: «suspension for a tail», the Tredmil racetrack, assessment of working capacity and endurance on indicators of the forced (limit) swimming, registration of coordination by means of the Rota-ROD device, tests according to higher nervous activity: navigation memory, a labyrinth Barnes, testing of forming of a conditioned reflex of passive avoiding, the Open field test, measurement of an animal force by means of the Grip-strength meter device (the test for grasp force). Results: the best result was shown by group of the animals receiving the product in a prescription №2 in a dose of 60 mg/kg (containing a superoxide scavenger). In this group of animals immobilization time at suspension for a tail with increase in duration of the overcome distance on the tredmil decreased, time of the forced (limit) swimming raised and also the locomotory activity and force of a grasp increased that demonstrated increase in physical endurance, working capacity and neuromuscular transfer. Conclusions: it is revealed that «Fit Tonus» moderately reduces the level of situational uneasiness of mice and promotes increase in working capacity and speed of neuromuscular transfer

Parametric generation of second sound in superfluid helium: linear stability and nonlinear dynamics

We report the experimental studies of a parametric excitation of a second sound (SS) by a first sound (FS) in a superfluid helium in a resonance cavity. The results on several topics in this system are presented: (i) The linear properties of the instability, namely, the threshold, its temperature and geometrical dependencies, and the spectra of SS just above the onset were measured. They were found to be in a good quantitative agreement with the theory. (ii) It was shown that the mechanism of SS amplitude saturation is due to the nonlinear attenuation of SS via three wave interactions between the SS waves. Strong low frequency amplitude fluctuations of SS above the threshold were observed. The spectra of these fluctuations had a universal shape with exponentially decaying tails. Furthermore, the spectral width grew continuously with the FS amplitude. The role of three and four wave interactions are discussed with respect to the nonlinear SS behavior. The first evidence of Gaussian statistics of the wave amplitudes for the parametrically generated wave ensemble was obtained. (iii) The experiments on simultaneous pumping of the FS and independent SS waves revealed new effects. Below the instability threshold, the SS phase conjugation as a result of three-wave interactions between the FS and SS waves was observed. Above the threshold two new effects were found: a giant amplification of the SS wave intensity and strong resonance oscillations of the SS wave amplitude as a function of the FS amplitude. Qualitative explanations of these effects are suggested.Comment: 73 pages, 23 figures. to appear in Phys. Rev. B, July 1 st (2001

Особенности ион-транспортных процессов в модели артериальной гипертензии

Aim. To study the ionic mechanisms which underlie regulation contractile activity of vascular smooth muscles and the erythrocytes membrane potential from spontaneously hypertensive rats.Materials and methods. The effect of acetylcholine (ACX), 10 μM, and Ca2+ -ionophore A23187, 10 μM, on the contractile reactions of isolated smooth muscle segments of the aorta from 11-week-old spontaneously hypertensive rats (SHR) and Wistar – Kyoto rats (WKY) induced by phenylephrine (PE), 1 μM, was measured by the mechanography. 11-week-old SHR were divided into control and experimental groups depending on the drug administration (amlodipine 10 mg/kg given intragastrically). Blood pressure (BP) in SHR was measured before and after treatment. The amplitude of the hyperpolarizating response (HO) and the activity of Ca2+-dependent K+-channels of the erythrocyte membrane of SHR were performed with potentiometric method.Results. In response to the stimulating effect of the ACX or the calcium ionophore A23187, the smooth muscle segments of the aorta from the WKY and SHR precontracted with PE were relaxed. To the addition of the ACX, the vascular segments of the SHR responded with a stronger dilatation than the WKY segments, but not the action of the Ca2+-ionophore. Treatment of SHR with blocker of Ca2+-channels of L-type amlodipine caused a decrease the BP, and an increase in the relaxing effect of intact aortic segments on the ACX and Ca2+-ionophore. There was an increase the amplitude of HO and activity of Ca2+-dependent K+-channels of the erythrocyte membrane from SHR.Conclusion. Relaxation of vascular smooth muscle in SHR is caused by changes in the endothelial function and Ca2+-dependent ionic conductivity of the myocyte membrane. An increase of the hyperpolarizating response of the erythrocyte membrane from rats with spontaneous hypertension is associated with activation of potassium channels. The selective effect on these intracellular targets can serve as a basis for the development of antihypertensive drugs.Цель исследования. Изучение ионных механизмов регуляции сократительной активности сосудистых гладких мышц и мембранного потенциала эритроцитов у спонтанно-гипертензивных крыс.Материалы и методы. Механографическим методом исследовано действие ацетилхолина (АЦХ), 10 мкМ, и Са2+-ионофора A23187, 10 мкМ, на контрактильные реакции изолированных гладкомышечных сегментов аорты 11-недельных спонтанно-гипертензивных крыс (spontaneously hypertensive rats, SHR) и крыс Wistar – Kyoto (WKY), индуцированные фенилэфрином (ФЭ), 1 мкМ. Крысы SHR были разделены на контрольную и экспериментальные группы в зависимости от типа получаемого лечения (амлодипин 10 мг/кг внутрижелудочно). У крыс SHR измеряли артериальное давление (АД) до и после лечения. Потенциометрическим методом оценивали величину гиперполяризационного ответа (ГО) и активность Са2+-зависимых К+-каналов мембраны эритроцитов крыс SHR. Результаты. В ответ на стимулирующее воздействие АЦХ и кальциевого ионофора А23187 происходило расслабление гладкомышечных сегментов аорты крыс WKY и SHR, предсокращенных адреномиметиком ФЭ. На добавление АЦХ сосудистые сегменты крыс SHR отвечали большей дилатацией, чем сегменты крыс WKY, но подобной тенденции не наблюдалось при действии Ca2+-ионофора. Внутрижелудочное введение крысам SHR блокатора Са2+-каналов L-типа амлодипина вызывало как снижение АД, так и значимое усиление расслабляющего действия холиномиметика и Са2+-ионофора на интактные сегменты аорты. У крыс SHR отмечено повышение амплитуды ГО активности Са2+-зависимых К+-каналов мембраны эритроцитов.Заключение. Дилатационные реакции сосудистых гладких мышц крыс SHR обусловлены изменением эндотелиальной функции и Са2+-зависимой ионной проводимости мембраны миоцитов. Увеличение гиперполяризации мембраны эритроцитов крыс со спонтанной гипертензией связано с активацией калиевых каналов. Селективное воздействие на данные внутриклеточные мишени может служить основой для разработки антигипертензивных препаратов

Error analysis in the process of interpretation training

The article deals with error analysis, one of the most essential components in the process of training interpreters, focuses on classification of errors in interpreting processes, and offers ways of preventing them to obtain the best results in the educational process