Multiwavelength generation in a random distributed feedback fiber laser using an all fiber Lyot filter

Multiwavelength lasing in the random distributed feedback fiber laser is demonstrated by employing an all fiber Lyot filter. Stable multiwavelength generation is obtained, with each line exhibiting subnanometer line-widths. A flat power distribution over multiple lines is obtained, which indicates that the power between lines is redistributed in nonlinear mixing processes. The multiwavelength generation is observed both in first and second Stokes waves

Local Fields without Restrictions on the Spectrum of 4-Momentum Operator and Relativistic Lindblad Equation

Quantum theory of Lorentz invariant local scalar fields without restrictions on 4-momentum spectrum is considered. The mass spectrum may be both discrete and continues and the square of mass as well as the energy may be positive or negative. Such fields can exist as part of a hidden matter in the Universe if they interact with ordinary fields very weakly. Generalization of Kallen-Lehmann representation for propagators of these fields is found. The considered generalized fields may violate CPT- invariance. Restrictions on mass-spectrum of CPT-violating fields are found. Local fields that annihilate vacuum state and violate CPT- invariance are constructed in this scope. Correct local relativistic generalization of Lindblad equation for density matrix is written for such fields. This generalization is particulary needed to describe the evolution of quantum system and measurement process in a unique way. Difficulties arising when the field annihilating the vacuum interacts with ordinary fields are discussed.Comment: Latex 23 pages, sent to "Foundations of Physics

Waveguide-saturable absorber fabricated by femtosecond pulses in YAG:Cr4+ crystal for Q-switched operation of Yb-fiber laser

A waveguide-saturable absorber with low propagation loss is fabricated by femtosecond pulses in YAG:Cr4+ crystal. Q-switch operation of a Yb fiber laser with the new saturable absorber having absorption saturation parameters similar to the bulk YAG:Cr4+ crystal is demonstrated

Blue laser cooling transitions in Tm I

We have studied possible candidates for laser cooling transitions in $^{169}$Tm in the spectral region 410 -- 420 nm. By means of saturation absorption spectroscopy we have measured the hyperfine structure and rates of two nearly closed cycling transitions from the ground state $4\textrm{f}^{13}6\textrm{s}^2(^2\textrm{F}_0)(J_g=7/2)$ to upper states $4\textrm{f}^{12}(^3\textrm{H}_5)5\textrm{d}_{3/2}6\textrm{s}^2(J_e=9/2)$ at 410.6 nm and $4\textrm{f}^{12}(^3\textrm{F}_4)5\textrm{d}_{5/2}6\textrm{s}^2(J_e=9/2)$ at 420.4 nm and evaluated the life times of the excited levels as 15.9(8) ns and 48(6) ns respectively. Decay rates from these levels to neighboring opposite-parity levels are evaluated by means of Hartree-Fock calculations. We conclude, that the strong transition at 410.6 nm has an optical leak rate of less then $2\cdot10^{-5}$ and can be used for efficient laser cooling of $^{169}$Tm from a thermal atomic beam. The hyperfine structure of two other even-parity levels which can be excited from the ground state at 409.5 nm and 418.9 nm is also measured by the same technique. In addition we give a calculated value of $7(2)$ s$^{-1}$ for the rate of magnetic-dipole transition at 1.14 $\mu$m between the fine structure levels $(J_g=7/2)\leftrightarrow(J'_g=5/2)$ of the ground state which can be considered as a candidate for applications in atomic clocks.Comment: 8 pages, 5 figure

FEATURES OF DIAGNOSTIC AND THERAPEUTIC TACTICS FOR BLUNT ABDOMINAL TRAUMA WITH DAMAGE TO THE PANCREAS

Abstract. Injuries of pancreas in the closed abdominal trauma remain the one of most challenging issues in diagnosis and choice of optimal therapy.Objectives. To analyze clinical results of the improved diagnostic and treatment tactics in patients with blunt abdominal trauma and damage to the pancreas.Material and methods. We report the results of treatment for 141 patients with pancreatic trauma treated from 1991 to 2015 at City Hospital No. 3 and City Hospital No. 40. All patients were divided into 2 groups. These groups were formed according to the time factor. The groups were comparable in age, gender, and pancreatic trauma severity. The study group consisted of 59 patients, treated in 2004-2015, and the comparison group consisted of 82 patients (1991–2003). The advanced diagnostic and treatment algorithm for the study group included modern instrumental diagnostic methods, such as ultrasound, computed tomography, diagnostic laparoscopy and improved surgical tactics to lower indications for omental plug, omentobursostomy, suturing capsule of pancreas and cholecystostomy.Results. This algorithm reduced the duration gap between hospitalization and surgery averagely from 10.7 to 4.0 hours, and the modified treatment tactics decreased the incidence of septic complications from 15.8% to 6.8%, and the mortality from 27.6% to 16.9%.Conclusion. As a rule, methods of radiodiagnosis detect only indirect signs of pancreatic injury in blunt abdominal trauma. It is advisable to perform omental plugging only as medical tactics of «damage control»

ОСОБЕННОСТИ ЛЕЧЕБНО-ДИАГНОСТИЧЕСКОЙ ТАКТИКИ ПРИ ЗАКРЫТОЙ ТРАВМЕ ЖИВОТА С ПОВРЕЖДЕНИЕМ ПОДЖЕЛУДОЧНОЙ ЖЕЛЕЗЫ

Abstract. Injuries of pancreas in the closed abdominal trauma remain the one of most challenging issues in diagnosis and choice of optimal therapy.Objectives. To analyze clinical results of the improved diagnostic and treatment tactics in patients with blunt abdominal trauma and damage to the pancreas.Material and methods. We report the results of treatment for 141 patients with pancreatic trauma treated from 1991 to 2015 at City Hospital No. 3 and City Hospital No. 40. All patients were divided into 2 groups. These groups were formed according to the time factor. The groups were comparable in age, gender, and pancreatic trauma severity. The study group consisted of 59 patients, treated in 2004-2015, and the comparison group consisted of 82 patients (1991–2003). The advanced diagnostic and treatment algorithm for the study group included modern instrumental diagnostic methods, such as ultrasound, computed tomography, diagnostic laparoscopy and improved surgical tactics to lower indications for omental plug, omentobursostomy, suturing capsule of pancreas and cholecystostomy.Results. This algorithm reduced the duration gap between hospitalization and surgery averagely from 10.7 to 4.0 hours, and the modified treatment tactics decreased the incidence of septic complications from 15.8% to 6.8%, and the mortality from 27.6% to 16.9%.Conclusion. As a rule, methods of radiodiagnosis detect only indirect signs of pancreatic injury in blunt abdominal trauma. It is advisable to perform omental plugging only as medical tactics of «damage control».Резюме. Травматические повреждения поджелудочной железы (ПЖ) при закрытой травме живота по трудности диагностики и выбора оптимальной лечебной тактики остаются одними из самых сложных среди травм органов брюшной полости.Цель. Анализ клинических результатов усовершенствованной лечебно-диагностической тактики у пострадавших с закрытой травмой живота с повреждением ПЖ.Материал и методы. Представлены результаты лечения 141 пострадавшего с закрытой травмой ПЖ, находившихся на лечении в городских больницах № 3 и № 40 города Санкт-Петербурга с 1991 по 2015 г. Все пациенты были разделены на 2 группы. Группы сформированы по временному фактору и были сопоставимы по половому и возрастному признакам, а также по тяжести повреждений ПЖ. Группу исследования составили 59 пострадавших, пролеченных в период с 2004 по 2015 г., группу срав- нения — 82 пациента (1991–2003 гг.). В основной группе в диагностический алгоритм были включены современные инструментальные методы диагностики, такие как ультразвуковое исследование, компьютерная томография, диагностическая лапароскопия, а также усовершенствована хирургическая тактика — сокращены показания к тампонированию, оментобурсостомии, отказ от ушивания капсулы железы, холецистостомии.Результаты. Использование данного диагностического алгоритма уменьшило время, проходящее от момента госпитализации до оказания пострадавшему оперативного пособия в среднем с 10,7 до 4,0 ч, а усовершенствование лечебной тактики снизило частоту гнойно-септических осложнений с 15,8 до 6,8%, а также общую летальность с 27,6 до 16,9%.Заключение. Методы лучевой диагностики как правило позволяют выявить лишь косвенные признаки повреждения ПЖ при закрытой травме живота. С целью уменьшения риска развития гнойно-септических осложнений целесообразно ограничить использование тампонирования сальниковой сумки лишь рамками лечебной тактики «damage control»