Strong resonant tunneling, level repulsion and spectral type for one-dimensional adiabatic quasi-periodic Schr\"{o}dinger operators

In this paper, we consider one dimensional adiabatic quasi-periodic Schr\"{o}dinger operators in the regime of strong resonant tunneling. We show the emergence of a level repulsion phenomenon which is seen to be very naturally related to the local spectral type of the operator: the more singular the spectrum, the weaker the repulsion

IAA Technology Development Center Report 2012

No abstract availabl

rac-12,14-Dicyclo­propyl-5,8,13,18,21-penta­oxapenta­cyclo­[13.8.0.02,11.04,9.017,22]tricosa-1(15),2(11),3,9(10),16,22(23)-hexa­ene

The mol­ecule of the title compound, C24H24O5, has crystallographic twofold symmetry, with the central O atom lying on the rotation axis. The dihedral angle between the best planes of the benzene rings fused to the oxepine fragment is 38.5 (1)°. The dioxine ring adopts a twist form with the ethyl­ene group C atoms deviating by 0.472 (5) and −0.248 (6) Å from the plane defined by the remaining ring atoms

Билобарное стентирование при опухолевом поражении печеночных протоков

The article presents the experience of treating severe group of patients with proximal tumors of the biliary tract with lesions of the hepatic ducts. Of 1170 patients who underwent minimally invasive surgery for neoplastic lesions of the bile ducts, in 212 cases, stenting is performed when the tumor Klatskin, metastatic liver lesions and lymph nodes of the hepatoduodenal ligament. Used two-stage method of restoring patency of the bile ducts, in which the endoprosthesis was performed in most cases after a preliminary external decompression of biliary hypertension. In 207 cases was installed 2 stent in hepatic duct, in 5 cases – 3 stent. The authors have developed an algorithm for the management of patients in the postoperative period to prepare the patient for a possible radical surgical intervention, resulting in 6 cases it was possible to perform liver resection. In the postoperative period after radical surgery 1 patient died, after stenting operations in proximal tumor of the bile ducts mortality was 11.8%. The authors showed the effectiveness of minimally invasive technologies for restoring the patency of the tumor affected the hepatic ducts, which increases the median survival of patients with proximal tumors of the bile ducts, and also prepare a small group of patients for radical surgery.В статье представлен опыт лечения тяжелой группы пациентов с проксимальными опухолями желчевыводящих путей с поражением печеночных протоков. Из 1170 больных, которым выполнены стентирующие малоинвазивные операции при опухолевом поражении желчных протоков, в 212 случаях эндопротезирование выполнено при опухоли Клатскина, метастатическом поражении печени и лимфатических узлов гепатодуоденальной связки. Применялась двухэтапная методика восстановления проходимости желчных протоков, при которой эндопротезирование выполнялось в большинстве случаев после предварительной наружной декомпрессии билиарной гипертензии. У 207 больных установлены 2 стента с целью реканализации протоков, пораженных опухолью, у 5 пациентов – 3 стента. Авторами разработан алгоритм ведения больных в послеоперационном периоде с целью подготовки больного к возможному радикальному оперативному вмешательству, благодаря чему в 6 случаях удалось выполнить резекцию печени. В послеоперационном периоде после радикальных операций умер 1 пациент, после стентирующих операций при проксимальном поражении желчных протоков летальность составила 11,8%. Авторы показали эффективность малоинвазивных технологий при восстановлении проходимости опухолью пораженных печеночных протоков, что позволяет увеличить медиану выживаемости больных с проксимальными опухолями желчных протоков, а также подготовить небольшую группу больных к радикальному оперативному вмешательству

All-fiber polarization-maintaining mode-locked laser operated at 980 nm

For the first time, to the best of our knowledge, we present an all-fiber polarization-maintaining passively mode-locked picosecond laser operated at 980 nm. The laser cavity had a ring configuration with a semiconductor saturable absorber mirror as a mode-locking element. As an active medium, we used a specially designed cladding-pumped . Yb-doped fiber with reduced cladding-to-core diameter ratio. The laser was self-starting and operated in the net cavity normal dispersion regime, where a spectral profile of the gain medium acted as a filter element. By intracavity spectral filtering, we achieved about 40 dB dominance of the signal wavelength at 980 nm over 1 mu m emission in a highly stable picosecond pulsed regime. The corresponding simulation was performed to extend the knowledge about laser operation. (C) 2020 Optical Society of America12 month embargo; published online: 9 April 2020This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

Enhanced (3) interactions of unamplified femtosecond Cr:forsterite laser pulses in photonic-crystal fibers

Enhancement of nonlinear optical interactions in the core of a photonic-crystal fiber allows severa

All-fiber mode-locked laser at 0.98 µm

We developed a highly efficient double-clad Yb-doped polarization-maintaining fiber to be implemented for small-signal amplification near 0.976 mu m. The fiber was designed to have a relatively small mode field diameter compatible with standard step-index single-mode optical fibers. Another feature of the fiber was a small threshold for 0.976 mu m signal amplification, which was achieved by a creation of a thin inner cladding (80 mu m diameter). The unique design of the fiber allowed us to construct successfully an all-fiber picoseconds mode-locked laser at 0.98 mu m for the first time to the best of our knowledge.This item from the UA Faculty Publications collection is made available by the University of Arizona with support from the University of Arizona Libraries. If you have questions, please contact us at [email protected]

All-fiber mode-locked laser at 977 nm

In this paper, we have developed Yb-doped fiber suitable for creation of all-fiber seed laser schemes operating near 977 nm. The fiber was based on a ring-doping design (cladding was partially doped with Yb-ions), which allowed us to fabricate a relatively small core and provide mode field diameter (MFD) of the active fiber comparable with standard fibers (to achieve small splicing losses with commercially available optical fibers) and, simultaneously, increase absorption from the cladding to keep a reasonably high lasing efficiency. So MFDx of the fiber was 12 μm, MFDy was 14 μm. Outer silica cladding of the active fiber was decreased to diameter of 80 μm and a special pump and signal combiner was used to inject pump and signal into the active fiber. Based on the developed Yb-doped fiber an all-fiber polarization maintaining mode-locked laser with central wavelength around 977 nm was demonstrated for the first time. SESAM was used as a saturable absorber. The laser was self-starting for pump powers above 4.6 W, with the output power of 3 mW. The autocorrelation was the best fitted with sech2 profile and pulse duration was estimated to be as long as 9.5 ps. The fundamental cavity frequency corresponded to the pulse repetition rate of 33.532 MHz. Signal-to-noise ratio measured in the radio frequency range was more than 50 dB, the line width was below 1 kHz, which indicate ultimate stability of the fabricated mode-lock laser.acceptedVersionPeer reviewe