[Complications of percutaneous nephrolithotomy and their management]

To date, percutaneous nephrolithotomy (PNL) is the standard treatment modality for large-volume renal stones and staghorn stones in patients with urolithiasis. Despite low invasiveness, this method is not without complications. This review discusses the most common complications and suggests methods for their prevention and appropriate management. To unify the study of complications they were categorized based on the modified Clavien classification. According to the available data, about 80% of the PNL complications belong to grade I-II complications and does not require any additional treatment. The most serious complications include sepsis, bleeding, and injury to nearby organs.

Study of crystal-field excitations and infrared active phonons in TbMnO3

The Tb³⁺ (4f ⁸) crystal-field (CF) excitations and the infrared phonons in TbMnO₃ are studied as a function of temperature and under an applied magnetic field. The phonon energy shifts reflect local displacement of the oxygen ions that contribute to the CF energy level shifts below 120 K and under magnetic field. The CF polarized transmission spectra provide interesting information about the debated nature of the excitations at 41, 65, 130 cm^-1. We also evaluate the contribution of the charge transfer mechanism to the magnetoelectric process in TbMnO₃ under magnetic field.

Switching of Magnons by Electric and Magnetic Fields in Multiferroic Borates

Electric manipulation of magnetic properties is a key problem of materials research. To fulfill the requirements of modern electronics, these processes must be shifted to high frequencies. In multiferroic materials, this may be achieved by electric and magnetic control of their fundamental excitations. Here we identify magnetic vibrations in multiferroic iron borates that are simultaneously sensitive to external electric and magnetic fields. Nearly 100% modulation of the terahertz radiation in an external field is demonstrated for SmFe_{3}(BO_{3})_{4}. High sensitivity can be explained by a modification of the spin orientation that controls the excitation conditions in multiferroic borates. These experiments demonstrate the possibility to alter terahertz magnetic properties of materials independently by external electric and magnetic fields.

[Experience in ureteroscopy for managing urolithiasis in one clinic. when does quantity transform into quality?]

INTRODUCTION

In recent years, there has been an increasing role of ureteroscopy in managing urinary tract calculi of various locations. Several studies have reported the relationship between the efficacy and safety of ureteroscopic interventions and surgeons skills and hospital caseload volume. The aim of our study was to assess the effectiveness of urethroscopic stone removal, the changes in treatment effectiveness, frequency and types of complications along with gaining experience in these interventions.

MATERIALS AND METHODS

We analyzed 4031 urolithiasis patients who were admitted to our urological department and underwent ureteroscopy from 2001 to 2013. To determine the effectiveness and safety of the method, as the experience gained, the time of observation was divided into three periods: from 2000 to 2004, from 2004 to 2009, from 2009 to 2013. The parameters were evaluated for the entire observation time and for each period.

RESULTS

Complete fragmentation of the stones was observed in 3628 (90%) patients, partial - in 219 (5.4%). No treatment effect was observed in 138 (3.4%) patients. The greatest effectiveness (96.94%) was seen in stones in the lower third of the ureter. The proportion of unsuccessful ureteroscopies was 5.7%, 4.5% and 3.5% for the periods 2000 -2004, 2005-2009 and 2009-2013, respectively (p=0.027). The incidence of acute postoperative pyelonephritis in the corresponding periods was 15.4%, 3.3% and 2.9% (p<0.001).

CONCLUSION

Ureteroscopy is an effective and safe treatment modality for managing upper urinary tract calculi. It is most effective in treating distal ureteral stones. The increase in the treatment effectiveness and the reduction in the incidence of complications along with gaining experience, suggests that these interventions should be practiced mainly in urology centers specializing in the care of patients with urolithiasis.

Revealing the nature of excitons in liquid exfoliated monolayer tungsten disulphide

Transition metal dichalcogenides (TMD) hold promise for applications in novel optoelectronic devices. There is therefore a need for materials that can be obtained in large quantities and with well understood optical properties. In this report, we present thorough photoluminescence (PL) investigations of monolayer tungsten disulphide obtained via liquid phase exfoliation. As shown by microscopy studies, the exfoliated nanosheets have dimensions of tens of nanometers and thickness of 2.5 monolayers on average. The monolayer content is about 20%. Our studies show that at low temperature the PL is dominated by excitons localized on nanosheet edges. As a consequence, the PL is strongly sensitive to the environment and exhibits an enhanced splitting in magnetic field. As the temperature is increased, the excitons are thermally excited out of the defect states and the dominant transition is that of the negatively charged exciton. Furthermore, upon excitation with a circularly polarized light, the PL retains a degree of polarization reaching 50% and inherited from the valley polarized photoexcited excitons. The studies of PL dynamics reveal that the PL lifetime is on the order of 10 ps, which is probably limited by non-radiative processes. Our results underline the potential of liquid exfoliated TMD monolayers in large scale optoelectronic devices.

[The work and health of adolescents: the gender aspects]

The purpose of the research is to study the gender aspects of the employment of adolescents, working in the time free from their study, and its impact on the livestyle and health, to assess the risks to health of students. There was studied the employment of senior pupils and students of vocational schools (1.2 thousand persons at the age from 14 till 18 years) in 5 regions of the Russian Federation. The results indicate to a prevalence of illegal employment of the minors. Among young men 62% work part time, among young women - 37%. Violations of hygienic requirements for working conditions and labor law violations are more common in young men employment. The first experience of work can render negative impact on the lifestyle and the state of health. In the working adolescents there is observed the higher prevalence of the behavioral risk factors (smoking, alcohol, drugs, sleep deprivation and others). Adolescents with work experience have lower health status. The analysis of odds ratio (OR), relative risk (RR), etiological fraction (EF) showed that to the higher health risk there are exposed teenagers working constantly throughout the year. In this group among girls there is a high prevalence of chronic diseases (RR = 2; OR = 3.9), of complaints of indigestion (RR = 2; OR = 2.5). In the group of young men, working continuously, the percentage of frequently ill with acute respiratory infections is higher (RR = 3.3; OR = 3.7), there is a higher number of complaints of heartburn (RR = 2.1; OR = 2.6), back pain (RR = 1.8; OR = 2.2). Working young men have higher health risk by comparison with working young women.

Scrutinizing Hall Effect in Mn_{1-x}Fe_{x}Si: Fermi Surface Evolution and Hidden Quantum Criticality

Separating between the ordinary Hall effect and anomalous Hall effect in the paramagnetic phase of Mn_{1-x}Fe_{x}Si reveals an ordinary Hall effect sign inversion associated with the hidden quantum critical (QC) point x^{*}∼0.11. The effective hole doping at intermediate Fe content leads to verifiable predictions in the field of fermiology, magnetic interactions, and QC phenomena in Mn_{1-x}Fe_{x}Si. The change of electron and hole concentrations is considered as a "driving force" for tuning the QC regime in Mn_{1-x}Fe_{x}Si via modifying the Ruderman-Kittel-Kasuya-Yosida exchange interaction within the Heisenberg model of magnetism.

Magnetoresistance of the high-pressure ferromagnetic phases (GaSb)2M (M=Cr,Mn)

For the first time magnetoresistance of the ferromagnetic high-pressure phases (GaSb)2M (M=Cr,Mn) has been measured in a wide range of temperature and magnetic field. It was found that the magnetic field dependencies of resistivity of both systems contain several contributions, including relatively smaller s-d exchange (Yosida-type) components in low fields and a quadratic positive term (PMR) in the low temperature region. The magnitude of the predominated negative term (NMR), which can be attributed to the quantum corrections effects, demonstrates a peak in the vicinity of Curie temperature.

Study of crystal-field excitations and infrared active phonons in the multiferroic hexagonal DyMnO3

In hexagonal DyMnO3, Dy(3+) crystal-field excitations are studied as a function of temperature and applied magnetic field. They are complemented with the measurements of infrared active phonon frequency shifts under applied magnetic field at T = 4.2 K. Between TN = 68 K and T = 10 K, the absence of Dy(3+) Kramers doublet splittings at either the C3 or the C3v site symmetries indicates that the Mn(3+) magnetic order effective exchange field has no component parallel to the c-axis at either site. Below T = 10 K, the ground state Kramers doublet splits under the Dy(3+) internal effective field as well as the applied magnetic field. Also, relatively strong infrared active phonon energy shifts are observed in magneto-infrared reflectance measurements at T = 4.2 K, allowing the calculation of the induced electric polarization changes as a function of the applied magnetic field. Such changes are associated with a large magnetoelectric effect in DyMnO3, arising from a charge transfer between Dy(3+) and apical oxygen ions.

Magnetic and micro-Raman studies of hexagonal-DyMnO3

Dc-susceptibility measurements and Raman active phonon frequencies of hexagonal DyMnO(3) retrace the Mn(3+) ions antiferromagnetic transition at T(N) ~ 70 K and their spin reorientation at T(SR) ~ 48 K. The temperature evolution of Raman active mode frequencies and their over-hardening are associated with Dy(3+) and Mn(3+) ion displacements below T(N) and with a spin-phonon coupling that involves apical oxygen.

Electrotransport and magnetic properties of Cr-GaSb phases synthesized under high pressure

The electrotransport and magnetic properties of new phases in the Cr-GaSb system were studied. The samples were prepared by high-pressure (P=6-8 GPa), high-temperature treatment and identified by x-ray diffraction and scanning electron microscopy. One of the CrGa(2)Sb(2) phases with an orthorhombic structure Iba2 has a combination of ferromagnetic and semiconductor properties and is potentially promising for spintronic applications. Another high-temperature phase is paramagnetic and identified as tetragonal I4/mcm.

Raman study of the antiferromagnetic phase transitions in hexagonal YMnO3 and LuMnO3

The A(1), E(1) and E(2) Raman active modes in hexagonal YMnO(3) and LuMnO(3) single crystals are studied as a function of temperature and compared with previous measurements. In addition to anharmonicity, some phonon frequencies show below T(N) anomalous temperature dependences that reflect the atomic displacements while some other phonon frequencies are more sensitive to the spin-phonon coupling.

Optical spectroscopy of bismuth-doped pure silica fiber preform

We report on the optical spectroscopy of monolithic fiber preform prepared from nanoporous bismuth-doped silica glass. The experiments reveal the existence of at least two different types of active centers and clearly demonstrate that the presence in the glass matrix of other dopant is not necessary to obtain the near-IR photoluminescence connected to Bismuth.

Evidence for electroactive excitation of the spin cycloid in TbMnO3

Terahertz electromagnetic excitations in the multiferroic TbMnO3 single crystals are investigated across the magnetic field induced rotation of the magnetic spin cycloid. In addition to the electromagnon along the a axis, the detailed polarization analysis of the experimental spectra suggests the existence of an electroactive excitation for ac electric fields of the electromagnetic wave along the crystallographic c axis. This excitation is possibly the electroactive eigenmode of the spin-cycloid in TbMnO3, which has been predicted within the inverse Dzyaloshinskii-Moriya mechanism of magnetoelectric coupling.

A micro-Raman study of a Pr(0.5)Ca(0.5)MnO(3) single crystal and thin films

We present a micro-Raman study of a high quality Pr(0.5)Ca(0.5)MnO(3) single crystal and thin films on SrTiO(3) and LaAlO(3) substrates. Ten A(g) and seven B(2g) Raman-active modes (simplified symmetry: Pmma space group) have been observed and correlated to charge ordering around T(co) = 240 K and antiferromagnetic spin-orbital ordering at T(N)∼ 170 K. Our data reveal that coherent Jahn-Teller MnO(6) distortions prevail at T<T(N). Moreover, the temperature dependence of the frequency and linewidth of the A(g) mode corresponding to in-plane oxygen atom rotation (∼268 cm(-1)) is analyzed within a polaron-like scheme that reflects a strong charge ordering to lattice coupling. The close similarities between the single crystal and the thin films' phonon evolution confirm that the thin films growth conditions have been optimized.

Optically detected magnetic resonance in bismuth-doped silica glass

We report on the observation of optically detected magnetic resonance (ODMR) in bismuth-doped silica glass. To explain the results of the experiment we adopted the intramolecular charge transfer model for Bi(5+)O(n)(2-) molecules in the frame of a semiempirical molecular orbitals approach. The results of our calculations are in good agreement with observed features of luminescence and ODMR experiments.

Relaxations as key to the magnetocapacitive effects in the perovskite manganites

We present a detailed dielectric study of the relaxation effects that occur in several perovskite rare-earth manganites, including the multiferroics TbMnO(3) and DyMnO(3). We demonstrate that the strong magnetocapacitive effects, observed for electrical fields E parallel c, are nearly completely governed by magnetic-state induced changes of the relaxation parameters. The multiferroic materials, which undergo a transition into a spiral magnetic state, show qualitatively different relaxation behavior than those compounds transferring into an A-type antiferromagnetic state. We ascribe the relaxations in both cases to the off-center motion of the manganese ions, which in the multiferroic systems also leads to the ferroelectric ordering.

Magnetic and magnetoelectric excitations in TbMnO3

Magnetic and magnetoelectric excitations in the multiferroic TbMnO3 have been investigated at terahertz frequencies. Using different experimental geometries we can clearly separate the electroactive excitations (electromagnons) from the magnetoactive modes, i.e., antiferromagnetic resonances. Two antiferromagnetic resonances were found to coincide with electromagnons. This indicates that both excitations belong to the same mode and the electromagnons can be excited by a magnetic ac field as well. In spite of the 90 degrees rotation of the magnetic cycloid in external magnetic fields, the electromagnons are observable for electric ac fields parallel to the a axis only.