A 10-hour period revealed in optical spectra of the highly variable WN8 Wolf-Rayet star WR 123

Aims. What is the origin of the large-amplitude variability in Wolf-Rayet WN8 stars in general and WR123 in particular? A dedicated spectroscopic campaign targets the ten-hour period previously found in the high-precision photometric data obtained by the MOST satellite. Methods. In June-August 2003 we obtained a series of high signal-to-noise, mid-resolution spectra from several sites in the {\lambda}{\lambda} 4000 - 6940 A^{\circ} domain. We also followed the star with occasional broadband (Johnson V) photometry. The acquired spectroscopy allowed a detailed study of spectral variability on timescales from \sim 5 minutes to months. Results. We find that all observed spectral lines of a given chemical element tend to show similar variations and that there is a good correlation between the lines of different elements, without any significant time delays, save the strong absorption components of the Hei lines, which tend to vary differently from the emission parts. We find a single sustained periodicity, P \sim 9.8 h, which is likely related to the relatively stable pulsations found in MOST photometry obtained one year later. In addition, seemingly stochastic, large-amplitude variations are also seen in all spectral lines on timescales of several hours to several days.Comment: 6 pages, 4 figures, 2 tables, data available on-line, accepted in A&A Research Note

On a systematic approach to defects in classical integrable field theories

We present an inverse scattering approach to defects in classical integrable field theories. Integrability is proved systematically by constructing the generating function of the infinite set of modified integrals of motion. The contribution of the defect to all orders is explicitely identified in terms of a defect matrix. The underlying geometric picture is that those defects correspond to Backlund transformations localized at a given point. A classification of defect matrices as well as the corresponding defect conditions is performed. The method is applied to a collection of well-known integrable models and previous results are recovered (and extended) directly as special cases. Finally, a brief discussion of the classical $r$-matrix approach in this context shows the relation to inhomogeneous lattice models and the need to resort to lattice regularizations of integrable field theories with defects.Comment: 27 pages, no figures. Final version accepted for publication. References added and section 5 amende

Inverse Spectral-Scattering Problem with Two Sets of Discrete Spectra for the Radial Schroedinger Equation

The Schroedinger equation on the half line is considered with a real-valued, integrable potential having a finite first moment. It is shown that the potential and the boundary conditions are uniquely determined by the data containing the discrete eigenvalues for a boundary condition at the origin, the continuous part of the spectral measure for that boundary condition, and a subset of the discrete eigenvalues for a different boundary condition. This result extends the celebrated two-spectrum uniqueness theorem of Borg and Marchenko to the case where there is also a continuous spectru

Bunching Transitions on Vicinal Surfaces and Quantum N-mers

We study vicinal crystal surfaces with the terrace-step-kink model on a discrete lattice. Including both a short-ranged attractive interaction and a long-ranged repulsive interaction arising from elastic forces, we discover a series of phases in which steps coalesce into bunches of n steps each. The value of n varies with temperature and the ratio of short to long range interaction strengths. We propose that the bunch phases have been observed in very recent experiments on Si surfaces. Within the context of a mapping of the model to a system of bosons on a 1D lattice, the bunch phases appear as quantum n-mers.Comment: 5 pages, RevTex; to appear in Phys. Rev. Let

Explicit solutions to the Korteweg-de Vries equation on the half line

Certain explicit solutions to the Korteweg-de Vries equation in the first quadrant of the $xt$-plane are presented. Such solutions involve algebraic combinations of truly elementary functions, and their initial values correspond to rational reflection coefficients in the associated Schr\"odinger equation. In the reflectionless case such solutions reduce to pure $N$-soliton solutions. An illustrative example is provided.Comment: 17 pages, no figure

Detailed analysis of shake structures in the KLL Auger spectrum of H2S

Shake processes of different origin are identified in the KLL Auger spectrum of H2S with unprecedented detail. The KLL Auger spectrum is presented together with the S 1s−1 photoelectron spectrum including the S 1s−1V−1nλ and S 1s−12p−1nλ shake-up satellites with V−1 and nλ indicating a hole in the valence shell and an unoccupied molecular orbital, respectively. By using different photon energies between 2476 and 4150 eV to record the KLL Auger spectra two different shake-up processes responsible for the satellite lines are identified. The first process is a shake-up during the Auger decay of the S 1s−1 core hole and can be described by S 1s−1→2p−2V−1nλ. The second process is the Auger decay of the shake-up satellite in the ionization process leading to S 1s−1V−1nλ→2p−2V−1nλ transitions. By combining the results of photoelectron and Auger spectra the involved V−1nλ levels are assigned

Комбинированная двухуровневая спинально-эпидуральная анестезия с фиксацией эпидурального катетера в подкожном канале с использованием модифицированной спинномозговой иглы

Aim of study To develop a new safe and reliable method of fixing an epidural catheter (EC), to study and compare the results of this method of fixing EC in the subcutaneous canal using a modified spinal needle (MSN) and an adhesive tape with a standard method of fixing an EC using only an adhesive tape when performing the combined double-segment spinal-epidural anesthesia (CDSEA) in the surgical treatment of fractures of the bones of the lower limb.Material and methods A comparative study of two methods of EC fixation was carried out in patients undergoing CDSEA during the surgical treatment of fractures of the bones of the lower limb. The patients were divided into two groups. The Group 1 (comparison, n=65), where EC was fixed at the site of epidural access with adhesive tape and the Group 2 (study, n=65), where EC was fixed in the subcutaneous canal using MSN and adhesive tape at the site of EC exit on the skin.Results In the study group, where EC was fixed in the subcutaneous canal using MSN and adhesive tape at the site of EC exit to the skin, there were 32.3% fewer cases with clinically significant dislocation (more than 15 to 30 mm) than in the comparison group, where EC was fixed at the site of epidural access only with adhesive tape.Conclusions A used spinal needle in a modified version can be used to perform EC in the subcutaneous canal. The dimensions of the MSN allow tunneling of the EC less traumatic and at a great distance from the site of the epidural access, which provides more reliable fixation of the EC, the number of cases with clinically significant + dislocation decreases, this allows for a longer and better postoperative epidural analgesia. This method does not solve all the problems of EC fixation; it is required to develop new methods of EC fixation, including fixation in the subcutaneous canal.ЦЕЛЬ Разработать новый безопасный и надежный способ фиксации эпидурального катетера (ЭК), изучить и сравнить результаты данного способа фиксации ЭК в подкожном канале с использованием модифицированной спинномозговой иглы (МСИ) и лейкопластырной наклейки со стандартным способом фиксации ЭК с использованием только лейкопластырной наклейки при проведении комбинированной двухуровневой спинально-эпидуральной анестезии (КДСЭА) при оперативном лечении переломов костей нижней конечности.МАТЕРИАЛ И МЕТОДЫ Было проведено сравнительное исследование двух способов фиксации ЭК у пациентов при проведении КДСЭА при оперативном лечении переломов костей нижней конечности. Пациенты были разделены на две группы: 1-я группа — сравнения, n=65, где ЭК фиксировали в месте эпидурального доступа лейкопластырной наклейкой; 2-я группа — исследования, n=65, где ЭК фиксировали в подкожном канале с использованием МСИ и лейкопластырной наклейки в месте выхода ЭК на кожу.РЕЗУЛЬТАТ В группе исследования, где ЭК фиксировали в подкожном канале с использованием МСИ и лейкопластырной наклейки в месте выхода ЭК на кожу, случаев с клинически значимой дислокации (от 15 до 30 мм) было на 32,3% меньше, чем в группе сравнения, где ЭК фиксировали в месте эпидурального доступа только лейкопластырной наклейкой.ВЫВОДЫ Использованную спинномозговую иглу в модифицированном варианте можно применить для проведения эпидурального катетера в подкожном канале. Размеры модифицированной спинномозговая иглы позволяют провести туннелирование эпидурального катетера менее травматично и на большое расстояние от места эпидурального доступа, что обеспечивает более надежную фиксацию эпидурального катетера, уменьшается количество случаев с клинически значимой наружной дислокацией, а это позволяет проводить более длительную и качественную послеоперационную эпидуральную анастезию. Данный способ не решает всех проблем фиксации эпидурального катетера, поэтому требуется разрабатывать новые способы его фиксации, в том числе и в подкожном канале

Inverse spectral problems for Dirac operators with summable matrix-valued potentials

We consider the direct and inverse spectral problems for Dirac operators on $(0,1)$ with matrix-valued potentials whose entries belong to $L_p(0,1)$, $p\in[1,\infty)$. We give a complete description of the spectral data (eigenvalues and suitably introduced norming matrices) for the operators under consideration and suggest a method for reconstructing the potential from the corresponding spectral data.Comment: 32 page

Simulation of Auger decay dynamics in the hard X-ray regime: HCl as a showcase

Auger decay after photoexcitation or photoemission of an electron from a deep inner shell in the hard X-ray regime can be rather complex, implying a multitude of phenomena such as multiple-step cascades, post-collision interaction (PCI), and electronic state-lifetime interference. Furthermore, in a molecule nuclear motion can also be triggered. Here we discuss a comprehensive theoretical method which allows us to analyze in great detail Auger spectra measured around an inner-shell ionization threshold. HCl photoexcited or photoionized around the deep Cl 1s threshold is chosen as a showcase. Our method allows calculating Auger cross sections considering the nature of the ground, intermediate and final states (bound or dissociative), and the evolution of the relaxation process, including both electron and nuclear dynamics. In particular, we show that we can understand and reproduce a so-called experimental 2D-map, consisting of a series of resonant Auger spectra measured at different photon energies, therefore obtaining a detailed picture of all above-mentioned dynamical phenomena at once