Subthreshold and near-threshold kaon and antikaon production in proton-nucleus reactions

The differential production cross sections of K^+ and K^- mesons have been measured at the ITEP proton synchrotron in p+Be, p+Cu collisions under lab angle of 10.5^0, respectively, at 1.7 and 2.25, 2.4 GeV beam energies. A detailed comparison of these data with the results of calculations within an appropriate folding model for incoherent primary proton-nucleon, secondary pion-nucleon kaon and antikaon production processes and processes associated with the creation of antikaons via the decay of intermediate phi mesons is given. We show that the strangeness exchange process YN->NNK^- gives a small contribution to the antikaon yield in the kinematics of the performed experiment. We argue that in the case when antikaon production processes are dominated by the channels with KK^- in the final state, the cross sections of the corresponding reactions are weakly influenced by the in-medium kaon and antikaon mean fields.Comment: 24 pages. accepted for publication at J.Phys.

Study of in-medium ω\omega meson properties in Ap, pA and AA collisions

We propose to investigate the in-medium properties of vector $\omega$ mesons at the normal nuclear density in Ap(pA) collisions and at higher density in AA collisions at the ITEP accelerator facility TWAC. Using of the inverse Ap kinematics will permit us to study the $\omega$ meson production in a wide momentum interval included the not yet explored range of small meson momenta relative to the projectile nuclei where the mass modification effect in nuclear matter is expected to be the strongest. Momentum dependence of the in-medium $\omega$ meson width will be studied in the traditional pA kinematics. We intend to use the electromagnetic calorimeter for reconstruction of the $\omega$ meson invariant mass by detecting photons from the $\omega \to \pi^{0}\gamma \to 3\gamma$ decay. The model calculations and simulations with RQMD generator show feasibility of the proposed experiment. Available now intensity of the ion beams provides a possibility to collect large statistics and make decisive conclusion about the $\omega$ meson properties at density of normal nuclei. At the second stage of the investigation the $\omega$ meson properties will be studied in AA collisions at higher density. Interpretation of these measurements will be based on the results obtained in Ap(pA) interactions. Further investigation of the in-medium properties of light unflavored and charmed mesons can be performed at ITEP and at GSI(FAIR) where higher ion energies will be accessible in near future.Comment: 26 pages, 10 figures, 2 table

An algebraic approach to the Tavis-Cummings problem

An algebraic method is introduced for an analytical solution of the eigenvalue problem of the Tavis-Cummings (TC) Hamiltonian, based on polynomially deformed su(2), i.e. su_n(2), algebras. In this method the eigenvalue problem is solved in terms of a specific perturbation theory, developed here up to third order. Generalization to the N-atom case of the Rabi frequency and dressed states is also provided. A remarkable enhancement of spontaneous emission of N atoms in a resonator is found to result from collective effects.Comment: 13 pages, 7 figure

ИНФЕКЦИЯ, ВЫЗВАННАЯ ACINETOBACTER BAUMANNII, В ОТДЕЛЕНИЯХ РЕАНИМАЦИИ И ИНТЕНСИВНОЙ ТЕРАПИИ МНОГОПРОФИЛЬНОГО ГОСПИТАЛЯ

The objective of the study: to investigate the course of infection, caused by A. baumannii, in the patients in the intensive care units of a general hospital. Methods. The retrospective cohort study was conducted, which included 830 patients of the intensive care wards suffering from nosocomial infections caused by Acinetobacter baumanii. The bacterial diagnostics and drug susceptibility testing were performed using the analyzer of ADAGIO (Bio Rad, USA), Vitex 2 Compact 60 (bio Mariex, France) and the bacteriological analyzer for testing of sterile blood cultures of Bact Alar 3D60 (bio Mariex, France). As a result, certain specific features of this infection were identified: higher frequency of this disease in the patients with unfavorable co-morbid background (p = 0.042), prevailing lesions of abdomen (p = 0.04), skin and soft tissues (p = 0.02), frequent manifestations of septic shock (14%; p = 0.025) with a high mortality rate (16%; p = 0.025). Conclusions. 1. In 28% of cases, Acinetobacter baumannii accounts for the development of nosocomial infection in the patients staying in the intensive care ward. 2. Abdomen (18%), skin and soft tissues (8%) are most frequent sites where lesions caused by this infection are diagnosed. 3. The co-infection caused by A. baumannii most often develops in the patients with compromised co-morbid background (Charlson score makes 4.6 ± 0.3), which explains the severity of their state (APACHE II score makes 18.0 ± 1.6), development of organ failures (SOFA scores make 6.00 ± 0.05) and high frequency of septic shock (14%; p = 0.025). 4. The high mortality is typical of the course of the infection caused by A. baumannii, (16% versus 5.6%) in the patients with nosocomial infections caused by the other gram-negative bacteria. Цель исследования: изучить особенности течения инфекции, вызванной A. baumannii, у пациентов отделений реанимации и интенсивной терапии (ОРИТ) многопрофильного госпиталя. Методика. Проведено ретроспективное, когортное исследование, в которое включено 830 пациентов ОРИТ с нозокомиальными инфекциями, вызванными Acinetobacter baumanii. Бактериологическую диагностику и тестирование на чувствительность к антибиотикам проводили с помощью анализатора ADAGIO (Bio Rad, USA), Vitex 2 Compact 60 (bio Mariex, France) и бактериологического анализатора для определения стерильных культур крови Bact Alar 3D60 (bio Mariex, France). В результате выделены особенности течения этой инфекции: увеличение частоты заболевания пациентов с неблагоприятным коморбидным фоном (p = 0,042), преимущественное поражение брюшной полости (p = 0,04), кожи и мягких тканей (p = 0,02), частые случаи развития клиники септического шока (14%; p = 0,025) с высоким показателем летальности (16%; p = 0,025). Выводы. 1. Acinetobacter baumannii в 28% случаев является причиной развития нозокомиальной инфекции у пациентов ОРИТ. 2. Наиболее часто диагностируемые локусы этой инфекции − это брюшная полость (18%), кожа и мягкие ткани (8%). 3. Присоединение инфекции, вызванной A. baumannii, чаще происходит у больных со скомпрометированным коморбидным фоном (оценка по шкале Charlson 4,6 ± 0,3), что обусловливает тяжесть их состояния (оценка по шкале APACHE II 18,0 ± 1,6 балла), развитие органных нарушений (по шкале SOFA 6,00 ± 0,05 балла), а также большую частоту развития септического шока (14%; p = 0,025). 4.Течение инфекции, вызванной A. baumannii, характеризуется высоким показателем госпитальной летальности (16% против 5,6%) у пациентов с нозокомиальными инфекциями, вызванными другими грамотрицательными микроорганизмами.

Transverse-momentum-dependent Multiplicities of Charged Hadrons in Muon-Deuteron Deep Inelastic Scattering

A semi-inclusive measurement of charged hadron multiplicities in deep inelastic muon scattering off an isoscalar target was performed using data collected by the COMPASS Collaboration at CERN. The following kinematic domain is covered by the data: photon virtuality $Q^{2}>1$ (GeV/$c$)$^2$, invariant mass of the hadronic system $W > 5$ GeV/$c^2$, Bjorken scaling variable in the range $0.003 < x < 0.4$, fraction of the virtual photon energy carried by the hadron in the range $0.2 < z < 0.8$, square of the hadron transverse momentum with respect to the virtual photon direction in the range 0.02 (GeV/$c)^2 < P_{\rm{hT}}^{2} < 3$ (GeV/$c$)$^2$. The multiplicities are presented as a function of $P_{\rm{hT}}^{2}$ in three-dimensional bins of $x$, $Q^2$, $z$ and compared to previous semi-inclusive measurements. We explore the small-$P_{\rm{hT}}^{2}$ region, i.e. $P_{\rm{hT}}^{2} < 1$ (GeV/$c$)$^2$, where hadron transverse momenta are expected to arise from non-perturbative effects, and also the domain of larger $P_{\rm{hT}}^{2}$, where contributions from higher-order perturbative QCD are expected to dominate. The multiplicities are fitted using a single-exponential function at small $P_{\rm{hT}}^{2}$ to study the dependence of the average transverse momentum $\langle P_{\rm{hT}}^{2}\rangle$ on $x$, $Q^2$ and $z$. The power-law behaviour of the multiplicities at large $P_{\rm{hT}}^{2}$ is investigated using various functional forms. The fits describe the data reasonably well over the full measured range.Comment: 28 pages, 20 figure

Resonant amplification of vortex-core oscillations by coherent magnetic-field pulses

Vortex structures in soft magnetic nanodisks are highly attractive due to their scientific beauty and potential technological applications. Here, we experimentally demonstrated the resonant amplification of vortex oscillations by application of simple coherent field pulses tuned to optimal width and time intervals. In order to investigate vortex excitations on the sub-ns time scale, we employed state-of-the-art time-resolved full-field soft X-ray microscopy of 70 ps temporal and 25 nm lateral resolution. We found that, due to the resonant enhancement of the vortex gyration motion, the signal input power can be significantly reduced to similar to 1 Oe in field strength, while increasing signal gains, by increasing the number of the optimal field pulses. We identified the origin of this behavior as the forced resonant amplification of vortex gyration. This work represents an important milestone towards the potential implementation of vortex oscillations in future magnetic vortex devices.open4

X-ray photoelectron spectroscopy of hybrid 3T3 NIH cell structures with internalized porous silicon nanoparticles on substrates of various materials

The work is related to the study of a biohybrid material based on mammalian 3T3 NIH mouse fibroblast cells with immobilized porous silicon particles including nanocrystals about 10 nm in size by photoelectron spectroscopy. The influence of the surface material of the substrate on which the biohybrid material is grown on the possibility of conducting studies of the physico-chemical state of the developed surface is studied. Nickel as well as gold and titanium, known for their biocompatibility, were used as surface materials for cell growth and subsequent internalization of silicon particles. The method of optical microscopy in the reflected light mode was used to assess the distribution of cells on surfaces. It is shown that the nickel surface is not suitable for the synthesis and subsequent studies of biohybrid structures. At the same time, on the surface of gold and titanium, cellular material and structures based on it are available for measurements, including by photoelectron spectroscopy, a high-precision method for studying the atoms charge state and the physico-chemical state of the surface as a whole. The X-ray photoelectronic spectra show all the main components expected to be detected after drying and subsequent vacuuming of the studied objects: the surface material of the substrates and arrays of cell cultures grown on the substrates. No signal from silicon atoms was detected on the nickel surface. In the case of a gold surface, the proximity of the binding energies of the gold core levels (substrate) and silicon (internalized particles) leads to the fact that the signal of gold atoms, which is significant in its intensity, does not allow detecting a signal from silicon atoms, which is weaker in intensity. The signal of silicon atoms in biohybrid structures is reliably detected only when using titanium substrates, including for a control sample containing porous silicon nanoparticles without incubation in cells. Thus, it is shown that the surface of the titanium foil can be used for studies by photoelectron spectroscopy of a biohybrid material based on mammalian 3T3 NIH mouse fibroblast cells with immobilized porous silicon particles.The obtained result is important for high-precision diagnostics of the physico-chemical state of biohybrid materials and structures based on them with a low content of silicon atoms when solving problems of studying the compatibility and possibilities of using silicon nanomaterials for medical, including therapeutic and other applications

Localization of the E. coli Dps protein molecules in a silicon wires under removal of residual salt

The work is related to the removal of residual salts in hybrid structures formed as a result of silicon wires arrays combining with a nanomaterial of natural origin – bacterial ferritin-like protein Dps. The study of the morphology and composition of the surface and the bulk part of the hybrid structure as a result of combination and subsequent washing in water was carried out. The method of metal-assisted wet chemical etching was used to obtain silicon wires arrays. To obtain recombinant protein, Escherichia coli BL21*(DE3) cells with chromatographic purification were used as producers. The combination of silicon wires with protein molecules was carried out by layering them in laboratory conditions, followed by drying. The residual salt found earlier in the hybrid material was removed by washing in water. The resulting hybrid material was studied by scanning electron microscopy and X-ray photoelectron spectroscopy. A well-proven complementary combination of scanning electron microscopy and X-ray photoelectron spectroscopy together with ion etching was used to study the morphology of the hybrid material “silicon wires – bacterial protein Dps” and the composition with physico-chemical state respectively. In arrays of silicon wires with a wire diameter of about 100 nm and a distance between them from submicron to nanometer sizes, protein was found as a result of layering and after treatment in water. At the same time, the amount of residual NaCl salt is minimized on the surface of the hybrid structure and in its volume. The obtained data can be used in the development of coating technology for the silicon wires developed surface available for functionalization with controlled delivery of biohybrid materia