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The photoluminescence spectra in an external magnetic field of an ensemble of InAs quantum dots grown by molecular beam epitaxy on a (001) GaAs substrate with a disorientation in the [010] direction are studied. A redistribution of the photoexcited carriers among different groups of dots under the influence of the magnetic field is observed. The concentration of quantum dots is determined by analyzing the data.

We report a surprisingly long spin relaxation time of electrons in Mn-doped p-GaAs. The spin relaxation time scales with the optical pumping and increases from 12 ns in the dark to 160 ns upon saturation. This behavior is associated with the difference in spin relaxation rates of electrons precessing in the fluctuating fields of ionized or neutral Mn acceptors, respectively. For the latter the antiferromagnetic exchange interaction between a Mn ion and a bound hole results in a partial compensation of these fluctuating fields, leading to the enhanced spin memory., 4 pages, 4 figures

Neutral pion transverse momentum spectra were measured in $p+\mathrm{C}$ and $p+\mathrm{Pb}$ collisions at $\sqrt{{s}_{NN}}=17.4\text{ }\text{ }\mathrm{GeV}$ at midrapidity ($2.3\ensuremath{\lesssim}{\ensuremath{\eta}}_{\mathrm{lab}}\ensuremath{\lesssim}3.0$) over the range $0.7\ensuremath{\lesssim}{p}_{T}\ensuremath{\lesssim}3.5\text{ }\text{ }\mathrm{GeV}/c$. The spectra are compared to ${\ensuremath{\pi}}^{0}$ spectra measured in $\mathrm{Pb}+\mathrm{Pb}$ collisions at $\sqrt{{s}_{NN}}=17.3\text{ }\text{ }\mathrm{GeV}$ in the same experiment. For a wide range of $\mathrm{Pb}+\mathrm{Pb}$ centralities (${N}_{\mathrm{part}}\ensuremath{\lesssim}300$), the yield of ${\ensuremath{\pi}}^{0}$'s with ${p}_{T}\ensuremath{\gtrsim}2\text{ }\text{ }\mathrm{GeV}/c$ is larger than or consistent with the $p+\mathrm{C}$ or $p+\mathrm{Pb}$ yields scaled with the number of nucleon-nucleon collisions (${N}_{\mathrm{coll}}$), while for central $\mathrm{Pb}+\mathrm{Pb}$ collisions with ${N}_{\mathrm{part}}\ensuremath{\gtrsim}350$, the ${\ensuremath{\pi}}^{0}$ yield is suppressed.

We study bound magnetic polarons (BMP) in a very diluted magnetic semiconductor CdMnTe by means of site selective spectroscopy. In zero magnetic field we detect a broad and asymmetric band with a characteristic spectral width of about 5 meV. When external magnetic fields are applied a new line appears in the emission spectrum. Remarkably, the spectral width of this line is reduced greatly down to 0.24 meV. We attribute such unusual behavior to the formation of BMP, effected by sizable fluctuations of local magnetic moments. The modifications of the optical spectra have been simulated by the Monte-Carlo method and calculated within an approach considering the nearest Mn ion. A quantitative agreement with the experiment is achieved without use of fitting parameters. It is demonstrated that the low-energy part of the emission spectra originates from the energetic relaxation of a complex consisting of a hole and its nearest Mn ion. It is also shown that the contribution to the narrow line arises from the remote Mn ions., Comment: 5 pages, 5 figures

1. A sign of the physicochemical softening of coal occurring as a result of its saturation with carbon dioxide under conditions of T≤Tcr(CO2) and P≥Pc characterizes a quite substantial antibatic change in the measured electric resistance and capacitance of coal caused by condensation of carbon dioxide in coal. As a result, the ultimate strength of the specimens decreases by factors of 5–10 and more, right up to complete dispersion. 2. The value of the pressure of capillary condensaton Pc depends on the structure of coal, its moisture content, and on the number of cycles of occurrence of condensate of the sorbate. The pressure of capillary condensation decreases from cycle to cycle and accordingly the value of the maximum measured resistance changes. The quantity of the characteristic fraction increases with increase of the number of cycles; the quantity of the coarsest fraction practically decreases to zero during 3–4 cycles. 3. Irregular fluctuations of the electrophysical parameters occurring under conditions in which carbon dioxide condenses in the porous structure of coal are also a characteristic sign of destruction of the porous structure of coal by carbon dioxide condensate.

Neutral pion transverse momentum spectra were measured in p+C and p+Pb collisions at sqrt[S{NN}]=17.4 GeV at midrapidity (2.3 less than or approximately equal eta{lab} less than or approximately equal 3.0) over the range 0.7 less than or approximately equal p{T} less than or approximately equal 3.5 GeV/c. The spectra are compared to pi{0} spectra measured in Pb+Pb collisions at sqrt[S{NN}]=17.3 GeV in the same experiment. For a wide range of Pb+Pb centralities (N{part} less than or approximately equal 300), the yield of pi{0}'s with p{T} greater than or approximately equal 2 GeV/c is larger than or consistent with the p+C or p+Pb yields scaled with the number of nucleon-nucleon collisions (N{coll}), while for central Pb+Pb collisions with N{part}greater than or approximately equal 350, the pi{0} yield is suppressed.

In recent decades, knowledge of the glacial history of the Last Pleistocene Glaciation in Eurasia has changed tremendously. According to recent investigations, a first major ice advance entered the Russian mainland as early as 80–100 ka ago, blocking all drainage and damming huge lakes in West Siberia and in European Russia. Drainage was diverted southward to the Caspian Sea and Black Sea. Whilst in the east this early Weichselian glaciation was the most extensive, so far no traces of this ice sheet have been found in the western regions. About 70 ka BP, a mid-Weichselian glaciation covered large parts of northern Russia and Siberia. Only the last, late Weichselian glaciation was restricted to the shelf areas of the Barents and Kara Sea and did not extend on to the Russian mainland. In the west, this was the most extensive Weichselian glaciation. In the Alps and in Britain, so far little evidence is found about the extent of the early Weichselian ice sheets.

In the Middle Pleistocene, Eurasia was affected by three major glaciations. The extent of the oldest glaciation, the Don glaciation, is still incompletely known. Also, for the Elsterian glaciation, the eastern limits are only roughly estimated. The ice sheet may have covered the west Siberian lowlands. However, it may have been the most extensive glaciation in eastern central Siberia. In the Saalian, the Older Saalian glaciation was the largest. It may have been the most extensive ice sheet in western Siberia, but the limits are still unclear, and west of the Urals the Saalian limit is not very well-defined. Middle and Younger Saalian glaciations were much less extensive. Correlation of the Nordic glaciations with the glacial sequence of the Alps is still difficult, and it seems clear that more glaciations occurred than Penck and Bruckner had originally envisioned.

Whilst glaciation of Antarctica goes back to the Oligocene, glaciation of South America and Greenland started some 14 Mya. Massive glaciation of the Northern Hemisphere started only some 1 Mya in the late Matuyama Chron. So far, evidence of this early glaciation is largely restricted to North America. Scandinavia may have been glaciated, but most of Asia probably was still ice-free.

We report circular-to-linear and linear-to-circular conversion of optical polarization by semiconductor quantum dots. The polarization conversion occurs under continuous wave excitation in the absence of any magnetic field. The effect originates from quantum interference of linearly and circularly polarized photon states, induced by the natural anisotropic shape of the self-assembled dots. The behavior can be qualitatively explained in terms of a pseudospin formalism.

We report on a complex nontrivial behavior of the optical anisotropy of quantum dots that is induced by a magnetic field in the plane of the sample. We find that the optical axis either rotates in the opposite direction to that of the magnetic field or remains fixed to a given crystalline direction. A theoretical analysis based on the exciton pseudospin Hamiltonian unambiguously demonstrates that these effects are induced by isotropic and anisotropic contributions to the heavy-hole Zeeman term, respectively. The latter is shown to be compensated by a built-in uniaxial anisotropy in a magnetic field B_c = 0.4 T, resulting in an optical response typical for symmetric quantum dots., Comment: 5 pages, 3 figures

The effect of the final state Coulomb interaction on particles produced in Pb+Pb collisions at 158 A GeV/c has been investigated in the WA98 experiment through the study of the pi-/pi+ and K-/K+ ratios measured as a function of transverse mass. While the ratio for kaons shows no significant transverse mass dependence, the pi-/pi+ ratio is enhanced at small transverse mass values with an enhancement that increases with centrality. A silicon pad detector located near the target is used to estimate the contribution of hyperon decays to the pi-/pi+ ratio. The comparison of results with predictions of the RQMD model in which the Coulomb interaction has been incorporated allows to place constraints on the time of the pion freeze-out., Comment: 9 pages, 12 figures

The optical properties of two-dimensional electron gases in ZnSe/(Zn,Be)Se and ZnSe/(Zn,Be,Mg)Se modulation-doped quantum wells with electron densities up to 1.4x10^{12} cm^{-2} were studied by photoluminescence, photoluminescence excitation and reflectivity in a temperature range between 1.6 and 70 K and in external magnetic fields up to 48 T. In these structures, the Fermi energy of the two-dimensional electron gas falls in the range between the trion binding energy and the exciton binding energy. Optical spectra in this regime are shown to be strongly influenced by the Coulomb interaction between electrons and photoexcited holes. In high magnetic fields, when the filling factor of the two-dimensional electron gas becomes smaller than two, a change from Landau-level-like spectra to exciton-like spectra occurs. We attempt to provide a phenomenological description of the evolution of optical spectra for quantum wells with strong Coulomb interactions., 12 pages, 12 figures

The article covers results of application of biospectrometry-based endoscopy with low-intensive He-Ne laser radiation in complex therapy of torpid esophageal, gastric, and duodenal ulcers. The authors are the first to offer a method based upon individual biophotometric control (autofluorescence, oxigination), which allows verification of the ulcerous process character, individual optimization of treatment and objective control of ulcer regression.

The ground state of negatively charged excitons (trions) in high magnetic fields is shown to be a dark triplet state, confirming long-standing theoretical predictions. Photoluminescence (PL), reflection, and PL excitation spectroscopy of CdTe quantum wells reveal that the dark triplet trion has lower energy than the singlet trion above 24 Tesla. The singlet-triplet crossover is "hidden" (i.e., the spectral lines themselves do not cross due to different Zeeman energies), but is confirmed by temperature-dependent PL above and below 24 T. The data also show two bright triplet states., 4 figures

Directed and elliptic flow of inclusive photons near mid-rapidity in $158 $A GeV Pb+Pb collisions has been studied. The data have been obtained with the photon spectrometer LEDA of the WA98 experiment at the CERN SPS. The flow strength has been measured for various centralities as a function of $p_T$ and rapidity over $0.18 < p_T < 1.5 \mathrm{GeV}/c$ and $2.3 < y < 2.9$. The angular anisotropy has been studied relative to an event plane obtained in the target fragmentation region that shows the elliptic flow to be in-plane. The elliptic flow has also been studied using two-particle correlations and shown to give similar results. A small directed flow component is observed. Both the directed and elliptic flow strengths increase with $p_T$. The photon flow results are used to estimate the corresponding neutral pion flow., 28 pages, 10 figures

Giant magnetic linear dichroism (MLD) is observed in the ferromagnetic semiconductor ${\mathrm{Ga}}_{0.98}{\mathrm{Mn}}_{0.02}\mathrm{As}$. The contribution to this effect induced by the spontaneous magnetization can be clearly identified by azimuthal dependencies. The spectral dependence of the effect in the range from 1.4 to 2.4 eV shows that the MLD induced by the spontaneous magnetization is strongly enhanced for excitations from the electronic states that are responsible for the ferromagnetism in this material. This spectral sensitivity and the size of the effect makes MLD a powerful tool for the study of $(\mathrm{III},\mathrm{Mn})\mathrm{V}$ alloys and similar novel ferromagnetic semiconductors.

Two-particle correlations of direct photons were measured in central 208Pb+208Pb collisions at 158A GeV. The invariant interferometric radii were extracted for 100

Static and time-resolved magneto-optical spectra of the ferromagnetic semiconductor (Ga,Mn)As show that a pulsed photoexcitation with a fluence of 10 microJ/cm(2) is equivalent to the application of an external magnetic field of about 1 mT, which relaxes with a decay time of 30 ps. This relaxation is attributed to the spin relaxation of electrons in the conduction band and is found to be not affected by interactions with Mn ions.

Information about the /spl gamma/ depth of interaction (DOI) in the crystal can help to improve the resolution uniformity in positron emission tomography cameras by reducing the blurring due to the parallax error. The parallax error is particularly severe for tomographs with small detector-to-detector distance, which is by itself a desirable feature, since it maximizes the detection solid angle and thus sensitivity. In this study we have developed simulations to determine the effect of a particular DOI correction method on resolution for some tomograph and crystal geometries. The considered DOI correction method relies on a double layer crystal configuration where the two crystals have different scintillation decay times. Round and octagonal PET camera geometries were considered. For each geometry two different crystal configurations were simulated: LSO/LSO and LSO/GSO. Empirical data were used to include scintillation decay time into the simulation. For specific configurations examined DOI correction was found to improve the resolution uniformity up to 37%.

We present comprehensive study of negatively charged exciton in high magnetic fields for filling factors ν < 1. In magneto-optical spectra the fine structure was found to be contributed by neutral exciton and different a set of bound states of charged exciton. These states were identified due to their unique polarization properties charecteristics in emission and absorption spectra. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

Results on the study of localized fluctuations in the multiplicity of charged particles and photons produced in 158A GeV/c Pb+Pb collisions are presented for varying centralities. The charged versus neutral particle multiplicity correlations in common phase space regions of varying azimuthal sizes are analyzed by two different methods. Various types of mixed events are constructed to probe fluctuations arising from different sources. The measured results are compared to those from simulations and from mixed events. The comparison indicates the presence of nonstatistical fluctuations in both the charged particle and photon multiplicities in limited azimuthal regions. However, no correlated charged-neutral fluctuations, a possible signature of formation of disoriented chiral condensates, are observed. An upper limit on the production of disoriented chiral condensates is set.

Several hadronic observables have been studied in central 158A GeV Pb+Pb collisions using data measured by the WA98 experiment at CERN: single pi(-) and K- production, as well as two- and three-pion interferometry. The Wiedemann-Heinz hydrodynamical model has been fitted to the pion spectrum, giving an estimate of the temperature and transverse flow velocity. Bose-Einstein correlations between two identified pi(-) have been analyzed as a function of k(T), using two different parametrizations. The results indicate that the source does not have a strictly boost invariant expansion or spend time in a long-lived intermediate phase. A comparison between data and a hydrodynamical based simulation shows very good agreement for the radii parameters as a function of k(T). The pion phase-space density at freeze-out has been measured, and agrees well with the Tomasik-Heinz model. A large pion chemical potential close to the condensation limit of m(pi) seems to be excluded. The three-pion Bose-Einstein interferometry shows a substantial contribution of the genuine three-pion correlation, but not quite as large as expected for a fully chaotic and symmetric source.

Optical properties of (Zn,Mn)Se/(Zn,Be)Se quantum wells containing a two-dimensional electron gas with densities varying from 109 to 5.5 × 1011 cm-2 have been studied in magnetic fields up to 45 T. A strong s — d exchange interaction of free electrons with magnetic Mn ions results in a giant Zeeman splitting of conduction band states, that has been exploited for manipulation with a spin polarization of the electron gas. Critical behavior of the photoluminescence and reflectivity linewidths and of the energy shift of the lines in magnetic fields in vicinity of integer filling factors 2 and 1 has been found and analyzed.

Optical properties of a two-dimensional electron gas in ZnSe/(Zn,Be,Mg)Se quantum well structures have been examined by means of photoluminescence and reflectivity techniques in external magnetic fields up to 50 T. For the studied structures, the Fermi energy of the two-dimensional electron gas falls in the range between the trion binding energy and the exciton binding energy, which keeps the dominating role of Coulombic interactions between electrons and photoexcited holes. Characteristic peculiarities of the optical spectra are discussed.

Excitons and charged excitons (trions) are investigated in ZnSe-based quantum well structures with (Zn,Be,Mg)Se and (Zn,Mg)(S,Se) barriers by means of magneto-optical spectroscopy. Binding energies of negatively (X−) and positively (X+) charged excitons are measured as functions of quantum well width, free carrier density and in external magnetic fields up to 47 T. The binding energy of X− shows a strong increase from 1.4 to 8.9 meV with decreasing quantum well width from 19.0 to 2.9 nm. The binding energies of X+ are about 25% smaller than the X− binding energies in the same structures. The magnetic field behavior of X− and X+ binding energies differ qualitatively. With growing magnetic field strength, X− increases its binding energy by 35–150%, while for X+ the binding energy decreases by 25%.

Selective detoxication of the blood from the portal vein was carried out in 31 patients with peritonitis complicated by multiple organ dysfunction including toxic hepatopathy. Selective extracorporeal detoxication of the blood from the portal vein possesses notable regional hemodynamic advantages in comparison with other variants of vascular approaches and essentially improves the transhepatic bloodflow. The authors emphasize that bifiltration cascade exchange portoplasmapheresis is a method of choice in severe toxic hepatopathy in patients with peritonitis. They recommend alternating bifiltration cascade exchange portoplasmapheresis with portohemofiltration in patients with toxic hepatonephropathy.

Photoluminescence spectra of modulation-doped quantum well structures based on IT—VT semiconductors (CdTe/CdMgTe and ZnSe/ZnBeMgSe) were studied in high magnetic fields it the range of 2D electron concentrations of (1 —5) x 1011 cm2 . The following peculiarities were found at low magnetic fields: (i) linear increase of thephotoluminescence energy with increasing magnetic fields, (ii) jumps in this dependence at integer filling-factors,(iii) periodical changing of Zeeman splitting. The observed behavior are interpreted in a frame of a model whichtakes into account combined exciton electron recombination processes in the presence of magnetic fields.Keywords: quantum wells, 2D electron gas, excitons, trions INTRODUCTION Several recent publications reported about investigations of photoluminescence (PL) spectra of quantum well(QW) structures based on 111—V and TI—VT semiconductors with two-dimensional electron gas (2DEG) in con-centration range from 1010 up to 1012 cm2 (i. e. with Fermi energy from 1 to 5 meV). These studies werecarried out at high magnetic fields. A linear shift of observed PL lines to the high energies with increasingmagnetic fields [1], jumps in the PL/absorption line position at integer filling-factors [2] and jumps of the PLintensity at integer filling factors [3, 5] were found. The observed picture is typical for 2D electron gas of highdensity "metallic regime" .

Photoluminescence, photoluminescence excitation (PLE) and reflectivity spectra of CdTe-based modulation-doped quantum well (QW) structures with 2DEG have been studied in magnetic fields. Resonant lines corresponding to combined optical transitions in which the photo-generation of excitons as well as trions is accompanied by the excitation of an additional electron from states below the Fermi level to states above the Fermi level were observed and analyzed.

Event-by-event fluctuations in the multiplicities of charged particles and photons, and the total transverse energy in 158A GeV Pb+Pb collisions are studied for a wide range of centralities. For narrow centrality bins the multiplicity and transverse energy distributions are found to be near perfect Gaussians. The effect of detector acceptance on the multiplicity fluctuations has been studied and demonstrated to follow statistical considerations. The centrality dependence of the charged particle multiplicity fluctuations in the measured data has been found to agree reasonably well with those obtained from a participant model. However, for photons the multiplicity fluctuations have been found to be lower compared to those obtained from a participant model. The multiplicity and transverse energy fluctuations have also been compared to those obtained from the VENUS event generator.

An optical method is suggested to determine the concentration of two-dimensional electrons in modulation-doped quantum wells at low and moderate electron densities between ${10}^{9}$ and $2\ifmmode\times\else\texttimes\fi{}{10}^{11}{\mathrm{cm}}^{\ensuremath{-}2}.$ The method is based on an analysis of magnetoreflectivity spectra of charged excitons (trions). The circular polarization degree and the oscillator strength of the charged excitons contain information about the density and spin polarization of two-dimensional electron gas. The method is applied to CdTe/(Cd,Mg)Te and ZnSe/(Zn,Mg)(S,Se) heterostructures.

Aim. To study the pro fi le of IL-6 in the early postoperative period after kidney transplantation and the factors that affect concentration of this cytokine. Methods and results . 28 kidney recipients were included in the study. It has been found that in most patients after surgery IL-6 was released, and the absence of such a reaction was a poor prognostic sign. Rate of increasing of the concentration and form of its curve within the fi rst postoperative day depended on the length of preservation, warm ischemia time, type of donor, and differed in recipients with normal and delayed initial graft function. Conclusion . Further study of the role of circulating factors in kidney transplantation would improve patient outcomes.

First results on the measurement of localized fluctuations in the multiplicity of charged particles and photons produced in central 158 A GeV Pb+Pb collisions are presented. The charged versus neutral correlations in common phase space regions of varying azimuthal size are analyzed by two different methods. The measured results are compared to those from simulations and to those from different types of mixed events. The comparison indicates the presence of non-statistical fluctuations in both charged particle and photon multiplicities in limited azimuthal regions. However, no correlated charge-neutral fluctuations are observed., Comment: 5 pages, 3 postscript figures

Results from the multiplicity distributions of inclusive photons and charged particles, scaling of particle multiplicities, event-by-event multiplicity fluctuations, and charged-neutral fluctuations in 158$\cdot A$ GeV Pb+Pb collisions are presented and discussed. A scaling of charged particle multiplicity as $N_{part}^{1.07\pm 0.05}$ and photons as $N_{part}^{1.12\pm 0.03}$ have been observed, indicating violation of naive wounded nucleon model. The analysis of localized charged-neutral fluctuation indicates a model-independent demonstration of non-statistical fluctuations in both charged particles and photons in limited azimuthal regions. However, no correlated charged-neutral fluctuations are observed., Talk given at the International Symposium on Nuclear Physics (ISNP-2000), Mumbai, India, 18-22 Dec 2000, Proceedings to be published in Pramana, Journal of Physics

CO2 laser system generating the train of ~200 ps pulses with total energy up to 5 J was put in operation in General Physics Institute of Russian Academy of Sciences (IOFRAN) recently. Initial ~100 ps 10.6 ?m laser pulse with energy 10 ?J was regeneratively amplified in 5 x 5 x 5 cm3 discharge volume X-ray preionized TB-CO2 discharge unit developed and manufactured in D.V.Efremov Scientific Research Institute of Electrophysical Apparatus (NIJEFA) in cooperation with JOFRAN. The results on upgrade of this unit towards obtaining 10 atm volume self-sustained discharge in C02:N2:He mixtures with reasonably high percentage of molecular gases are reported. Owing to this upgrade free running mode laser radiation energy B1 (when the unit was equipped with unstable telescopic resonator) at 6 atm was increased up to 22.2 J, which corresponds to specific energy extraction 5.4 J/l/atm and efficiency 4.5%. The estimated value of B1 from such a laser at 10 atm is 15 J. It corresponds to peak power of regeneratively amplified 2 ps 10 ?m pulse formed in master oscillator of laser system N1.5 TW. Prospective of further upgrade of laser system using new 10 x 10 x 100 cm3 discharge volume 10 atm TE-C02 discharge unit which is under construction now in NIIEFA in the network of ISTC Project #1072 is discussed.

Excitons and charged excitons (trions) are investigated in ZnSe-based quantum well structures with (Zn,Be,Mg)Se and (Zn,Mg)(S,Se) barriers by means of magneto-optical spectroscopy. Binding energies of negatively ${(X}^{\ensuremath{-}})$ and positively ${(X}^{+})$ charged excitons are measured as functions of quantum well width, and free carrier density and in external magnetic fields up to 47 T. The binding energy of ${X}^{\ensuremath{-}}$ shows a strong increase from 1.4 to 8.9 meV with decreasing quantum well width from 190 to $29 \AA{}.$ The binding energies of ${X}^{+}$ are about 25% smaller than the ${X}^{\ensuremath{-}}$ binding energy in the same structures. The magnetic field behavior of ${X}^{\ensuremath{-}}$ and ${X}^{+}$ binding energies differ qualitatively. With growing magnetic field strength, ${X}^{\ensuremath{-}}$ increases its binding energy by 35\char21{}150%, while for ${X}^{+}$ it decreases by 25%. Zeeman spin splittings and oscillator strengths of excitons and trions are measured and discussed.

Hetaryl-substituted aminomethylenemalonates obtained by the condensation of aminoazoles with 2-alkoxymethylenemalonates are commonly used for the synthesis of biologically active azolopyrimidines [1, 2]. However, cyclization of hetaryl-substituted aminomethylenemalonates to give azolopyrimidines often proceeds only at high temperature or under upon microwave activation [1] or by using special reagents [2]. In the present work, we found that brief heating of diethyl aminomethylenemalonates 1a and 1b in ethanol in the presence of sodium ethylate leads to the formation of mesoionic 1,2,4-triazolo[4,3-a]pyrimidin-5-ones 2a or 2b in high yield. This reaction does not occur upon heating aminomethylenemalonates 1a or 1b with tertiary aliphatic amines in ethanol at reflux. However, heating esters 1 with primary or secondary amines in ethanol or acetonitrile at reflux leads to nucleophilic substitution of the malonate ester and formation of amidines 3a-c in high yield.

An approach is proposed to determine parameters of homogeneous and inhomogeneous broadening for reflection lines of quasi-two-dimensional excitons in semiconductor quantum well structures. A phenomenological model is developed taking into account fluctuations of the exciton energy which are expected to cause inhomogeneous broadening of exciton reflectivity lines. This concept is applied to magneto-optical studies of CdTe/(Cd,Mg)Te single quantum well heterostructures containing a two-dimensional electron gas. By the analysis of excitonic reflection spectra in magnetic fields the parameters of homogeneous and inhomogeneous broadening of the exciton as well as their temperature dependencies were obtained., 13 pages, 4 figures

Three-particle correlations have been measured for identified pi(-) from central 158A GeV Pb+Pb collisions by the WA98 experiment at CERN. A substantial contribution of the genuine three-body correlation has been found as expected for a mainly chaotic and symmetric source.

The authors have studied the production of hadrons and photons in the reaction Pb(Pb, X) at 158 A.GeV. They have applied the discrete wavelet transform to the photon and charged-particle correlations in order to obtain a set of father function coefficients. They try to explain the multiplicity fluctuations by means of localized disoriented chiral condensate domains. (7 refs). A detailed analysis of the phase space distributions of charged particles and photons have been carried out using two independent methods. The results indicate the presence of nonstatistical fluctuations in localized regions of phase space.

Combined exciton-electron processes were studied in modulation doped quantum well structures in magnetic fields. In the case of such combined processes an incident photon creates an exciton and induces a transition of an additional electron between two Landau levels. In the present work we found the combined process in which the incident photon creates a trion (negatively charged exciton-electron complex) and also promotes the inter-Landau level transition of an additional electron. Such combined processes are found and studied in CdTe/CdMgTe and ZnSe/ZnMgSSe modulation-doped quantum wells containing two dimensional electron gas of low and moderate density.

In laser isotope separation experiments a high-speed IR recording camera ITMGT has been used. With the help of this camera we were first to realize photographic recording of the spatiotemporal radiation structure in the chemical reactor located inside the resonator of a high-power CO 2 laser. The obtained photographs reveal spatial nonuniformity of the radiation structure and self-focusing of laser radiation inside the resonator. Owing to the obtained information it has become possible to study the physics of self-focusing initiation in media with nonlinear absorption of IR radiation and this information will be useful for optimization of the processes of isotope enrichment by CO 2 laser radiation.

Study of elliptic emission for identified particles has been performed in 158A GeV Pb+Pb collisions near mid-rapidity region. Our preliminary results indicate the existence of the in-plane elliptic emission for {pi}{sup +} and proton, and out-of-plane elliptic emission for K+ in semi-central collisions. In addition, two-pion interferometry is studied as a function of the pair direction relative to the reaction plane.