Features of Seasonal Sea Level Oscillations in the Russian Arctic Seas

Based on the analysis of long series of monthly mean sea level values from the database of the PSMSL and ESIMO portals, we obtained estimates of the mean and extreme amplitudes of seasonal oscillations. The mean amplitude of annual sea level oscillations in the White Sea is 7 cm, in the Barents Sea is 9–10 cm, in the Kara Sea, is 8–9 cm, in the Laptev Sea, is 10–11 cm, in the East Siberian and Chukchi seas is 13–14 cm. In the estuarine areas of seas, the amplitude of annual oscillations increases, and the semiannual, third-annual, and quarter-annual components appear in the sea level spectra. They are formed due to the asymmetry of the seasonal sea level variation with a sharp maximum during the flood period in June. Interannual changes in the amplitude of seasonal oscillations were identified and estimates of their extreme values were obtained. In some years, the amplitude of seasonal oscillations reaches 50 cm in the Yenisei Gulf and Gulf of Ob, 60 cm near the mouth of the Lena River, and 75 cm at the mouth of the Olenek River.

Method of the equivalent photons for modulated electron beam

It is shown in this work that electromagnetic self-field of the periodically density modulated electron bunch can be considered as the beam of the equivalent photons (pseudo-photons), collimated along the electron velocity. Pseudo-photon spectrum includes both the incoherent contribution being proportional to number of electrons in the bunch and the coherent part with the sharp maximum corresponding the modulation frequency. Method of the equivalent photons can be applied for description of the interaction between the electron bunch and a crystal that leads to generation of the coherent parametric X-ray radiation by the modulated bunches exited from the undulator of the X-ray free electron laser. It provides the possibility to obtain the X-ray pulses directed at the large angle to the electron velocity where intensity of the background radiation essentially decreased. It is defined the conditions when the spectral and angular distributions of the coherent pseudo-photons can be compared with the analogous values for the pulses of the X-ray laser.

Dome C coherence time statistics from DIMM data

ABSTRACT We present a reanalysis of several years of DIMM data at the site of Dome C, Antarctica, to provide measurements of the coherence time τ0. Statistics and seasonal behaviour of τ0 are given at two heights above the ground, 3 and 8 m, for the wavelength λ = 500 nm. We found an annual median value of 2.9 ms at the height of 8 m. A few measurements could also be obtained at the height of 20 m and give a median value of 6 ms during the period June–September. For the first time, we provide measurements of τ0 in daytime during the summer, which appears to show the same time dependence as the seeing with a sharp maximum at 5 pm local time. Exceptional values of τ0 above 10 ms are met at this particular moment. The continuous slow variations of turbulence conditions during the day offers a natural test bed for a solar adaptive optics system.

Variational procedure leading from Davidson potentials to the E(5)and X(5) critical point symmetries

Davidson potentials of the form β^2 + β0^4/β^2, when used in the original Bohr Hamiltonian for γ-independent potentials bridge the U(5) and 0(6) symmetries. Using a variational procedure, we determine for each value of angular momentum L the value of β0 at which the derivative of the energy ratio RL = E(L)/E(2) with respect to β0 has a sharp maximum, the collection of RL values at these points forming a band which practically coincides with the ground state band of the E(5) model, corresponding to the critical point in the shape phase transition from U(5) to Ο(6). The same potentials, when used in the Bohr Hamiltonian after separating variables as in the X(5) model, bridge the U(5) and SU(3) symmetries, the same variational procedure leading to a band which practically coincides with the ground state band of the X(5) model, corresponding to the critical point of the U(5) to SU(3) shape phase transition. A new derivation of the Holmberg-Lipas formula for nuclear energy spectra is obtained as a by-product.

Distinguishing Features and Identification Criteria for K-Dioctahedral 1M Micas (Illite-Aluminoceladonite and Illite-Glauconite-Celadonite Series) from Middle-Infrared Spectroscopy Data

A representative collection of K-dioctahedral 1M micas ranging in composition from (Mg, Fe)-poor illites to aluminoceladonites through Mg-rich illites (Fe-poor varieties) and from Fe-bearing, Mg-rich illites to celadonites through Fe-illites, Al-glauconites and glauconites (Fe-bearing varieties) was studied by Fourier-transform infrared (FTIR) spectroscopy in the middle-infrared region. Analysis and comparison of the relationships between the band positions and cation compositions of Fe-poor and Fe-bearing K-dioctahedral micas provided a generalized set of FTIR identification criteria that include the band positions and profiles in the regions of Si–O bending, Si–O stretching, and OH-stretching vibrations. FTIR data allow unambiguous identification of illites, aluminoceladonites, and celadonites, as well as distinction between Fe-illites and illites proper, as well as between Al-glauconites and glauconites. Specifically, a sharp maximum from the AlOHMg stretching vibration at ~3600 cm−1, the presence of a MgOHMg stretching vibration at 3583–3585 cm−1, as well as characteristic band positions in the Si–O bending (435–439, 468–472 and 509–520 cm−1) and stretching regions (985–1012 and 1090–1112 cm−1) are clearly indicative of aluminoceladonite. The distinction between Fe-illites and Al-glauconites, which have similar FTIR features, requires data on cation composition and unit-cell parameters.

Сегнетоэлектрические фазовые переходы в Sr-=SUB=-9-=/SUB=-Tm(VO_4)-=SUB=-7-=/SUB=- при замещении стронция на кальций и свинец

By solid-phase synthesis at 1373 K in Sr9-xMexTm (VO4)7 systems the solid solutions with Me = Ca (0≤ x≤2) and Me = Pb (0≤ x≤1) were obtained. Single-phase samples at room temperature are isostructural to the Ca3(VO4)2 ferroelectric (space group (sp.gr.) R3c, Z = 6). Substances are characterized by X-ray phase analysis (XRD), second optical harmonic generation (SHG), and dielectric spectroscopy. The intensity of the SHG signal change depending on the substitution cation and its concentration varies in the range of 30-50 units relative to the quartz standard. A reversible ferroelectric phase transition was found in the temperature range 850–960 K. The transition is accompanied by a sharp maximum in the temperature dependence of the dielectric constant. The absence of a SHG signal above the transition temperature indicates the centrosymmetry of the paraelectric phase.

Characterising tropospheric O₃ and CO around Frankfurt over the period 1994–2012 based on MOZAIC–IAGOS aircraft measurements

In the framework of the MOZAIC–IAGOS programme, vertical profiles of ozone (O3) and carbon monoxide (CO) have been available since 1994 and 2002, respectively. This study investigates the variability and trend of both species in three tropospheric layers above the German airports Frankfurt and Munich. About 21 300 flights have taken place over the period 1994–2012, which represents the worldwide densest vertical in situ data set of O3 and CO (with ∼ 96 flights per month on average). The mean vertical profile of ozone shows a strong gradient in the first kilometre during the whole year and in the tropopause region in spring and summer. The mean vertical profile of CO is characterised by high mixing ratios at the ground, a strong decrease in the first kilometre, in particular in winter and autumn, and a moderate one in the free troposphere. O3 minimises in November–December and shows a broad spring/summer maximum in the lower and mid-troposphere and a sharp maximum in summer in the upper troposphere. The seasonal variation of CO shows a broad minimum in July–October close to the surface and in September–October it occurs higher in the troposphere, while the maximum occurs in February–April in the whole troposphere. Over the period 1994–2012, O3 has changed insignificantly (at a 95 % confidence level), except in winter where a slightly significant increase (from +0.83 [+0.13;+1.67] % yr−1 in the LT to +0.62 [+0.02;+1.22] % yr−1 in the UT, relative to the reference year 2000) is found. The O3 5th percentile shows similar upward trends at the annual scale in all three tropospheric layers. All trends remain insignificant for the O3 95th percentile. In contrast, for CO the mean as well as its 5th and 95th percentiles decrease both at the annual scale and at the seasonal scale in winter, spring and summer (although not always in all three tropospheric layers) with trends ranging between −1.22 [−2.27;−0.47] and −2.63 [−4.54;−1.42] % yr−1, relative to the reference year 2004. However, all CO trends remain insignificant in autumn. The phase of the seasonal variation of O3 was found to change in the troposphere. The O3 maxima moves forward in time at a rate of −17.8 ± 11.5 days decade−1 in the lower troposphere, in general agreement with previous studies. Interestingly, this seasonal shift is shown to persist in the mid-troposphere (−7.8 ± 4.2 days decade−1) but turns insignificant in the upper troposphere.

Magnetoresistance and Magnetic Properties CexMn1-xS

The transport and magnetic properties of cation-substituted manganese sulphides CexMn1-ХS in the 4K - 450K temperature range in magnetic fields up to 90 kOe are studied. The hysteresis of curve magnetization for X=0.01 and nonlinear field behavior of the magnetization at X = 0.05, the sharp Curie temperature drop were found. The sharp maximum in the temperature dependence of resistivity was observed. The shift of the maximum temperature to low temperatures at cerium ion concentration increasing and in magnetic field was established. Model of orbital polaron for explanation of experimental datа was used.