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Compression of 250-fs, 1-µJ pulses from a KLM Yb:YAG thin-disk oscillator down to 9.1 fs is demonstrated. A kagomé-PCF with a 36-µm core-diameter is used with a pressure gradient from 0 to 40 bar of krypton. Compression to 22 fs is achieved by 1200 fs2 group-delay-dispersion provided by chirped mirrors. By coupling the output into a second kagomé-PCF with a pressure gradient from 0 to 25 bar of argon, octave spanning spectral broadening via the soliton-effect is observed at 18-W average output power. Self-compression to 9.1 fs is measured, with compressibility to 5 fs predicted. Also observed is strong emission in the visible via dispersive wave generation, amounting to 4% of the total output power.
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We demonstrate a simple scheme for dual frequency comb spectroscopy in which the second frequency comb is generated by propagating the primary pulse train through a dazzler. The two frequency combs are combined behind a Mach-Zehnder interferometer, and the optical spectrum is read out by an rf-spectrum analyzer. The method is applied to record the overtone absorption spectrum of C2H2 (acetylene) in the wavelength region around 1.03 µm. A spectrum with a resolution of 4 cm(-1) is obtained, which compares well with that from the HITRAN database. A simple method for improving the spectral resolution is demonstrated.
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We report on the development and manufacturing of two different types of high-dispersive mirrors (HDM). One of them provides a record value for the group delay dispersion (GDD) of -4000 fs2 and covers the wavelength range of 1027-1033 nm, whereas the other one provides -3000 fs2 over the wavelength range of 1020-1040 nm. Both of the fabricated mirrors exhibit a reflectance of >99.9% and are well suited for intracavity applications. Mirrors of the second type have been successfully employed in a Kerr-lens mode-locked Yb:YAG thin-disk oscillator for the generation of 200-fs pulses with multi-10-W average power.
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We demonstrate a self-starting Kerr-lens mode-locked (KLM) Yb:YAG thin-disk oscillator operating in the regime of positive intracavity group-delay dispersion (GDD). It delivers 1.7 ps pulses at an average power of 17 W and a repetition rate of 40 MHz. Dispersive mirrors compress the pulses to a duration of 190 fs (assuming sech2 shape; Fourier limit: 150 fs) at an average power level of 11 W. To our knowledge, this is the first KLM thin-disk oscillator with positive GDD. Output powers of up to 30 W were achieved with an increased output coupler transmission and intracavity GDD. We demonstrate increase of the pulse energy with increasing positive intracavity GDD, limited by difficulties in initiating mode-locking.
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We demonstrate a power-scalable Kerr-lens mode-locked Yb:YAG thin-disk oscillator. It delivers 200 fs pulses at an average power of 17 W and a repetition rate of 40 MHz. At an increased (180 W) pump power level, the laser produces 270 fs 1.1 µJ pulses at an average power of 45 W (optical-to-optical efficiency of 25%). Semiconductor-saturable-absorber-mirror-assisted Kerr-lens mode locking (KLM) and pure KLM with a hard aperture show similar performance. To our knowledge, these are the shortest pulses achieved from a mode-locked Yb:YAG disk oscillator and this is the first demonstration of a Kerr-lens mode-locked thin-disk laser.
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The objective of this paper is to analyze the data from scientific literature and available recommendations for health professionals on healthcare providing to pediatric population in the events associated with risk of radiation exposure. Over the past sixty years there were several large scale radiological events with a large number of chil dren affected, namely the atomic bombing of Hiroshima and Nagasaki, accident at the Chornobyl nuclear power plant, contact to 137Cs radiation source unutilized at the hospital shutdown in Brazil etc. Further research has crys tallized injuries and health disorders in the survived children in all cases being much more significant vs. other pop ulations. Analysis of circumstances and features of a number of emergency situations or incidents in the nuclear industry for several decades has shown a high probability of radioactive materials release into the environment. The danger of terrorism with the use of ionizing radiation sources resulting in a considered inevitable hazard to the chil dren is estimated as serious in recent years and deserves an especial mention here.
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Atenção à Saúde , Brasil , Radioisótopos de Césio , Criança , Humanos , Liberação Nociva de Radioativos , TerrorismoRESUMO
STUDY OBJECTIVE: To summarize the verified clinical and epidemiological data on the natural history of non cancer endocrine disease in remote period after the ChNPP accident in survivors of adult and children age. MATERIALS AND METHODS: Retrospective estimation was carried out of data on 24,588 adult persons and 20,087 chil dren survived after the ChNNP accident and being healthy or having any diseases. Data were retrieved from database of the Clinical Epidemiological Registry (CER), NRCRM for the 23 years (1992-2014) of survey. Average total external radiation dose in adults was 0.187 Gy, range of thyroid dose in children was 0.1-1.55 Gy. These data were verifies in a separate clinical study. Anthropometric, laboratory biochemical and hormonal assay values, thyroid ultrasound imaging patterns and radiation dose values were retrieved for the study. RESULTS: Retrospective data review for the 1992-2014 period indicated that incidence of thyroid disease in all per sons survived after the ChNPP accident run at 40.29% with 35.37% among the clean up workers, 27.24% among evac uees, and 28.6% among population of contaminated territories that all is significantly (p < 0.0001) higher vs. the entire population of Ukraine (3.9%). Following non cancer endocrine diseases were most prevalent in the ChNPP acci dent survivors: nodular goiter (14.35%), chronic autoimmune thyroiditis (~8%), pre obesity and obesity (41.9% and 36.8% respectively), prediabetes and diabetes mellitus (15.5% and 21.4% respectively). Nodular goiter (21.8%), chronic autoimmune thyroiditis (12.95%), pre obesity and obesity (41.71% and 33.61% respectively), and predia betes and diabetes mellitus (8.6% and 12.15% respectively) were most often diagnosed in the ChNPP accident clean up workers. Children evacuated from the 30 kilometer exclusion zone were a critical population group. They were diagnosed diffuse non toxic goiter in 43.68%, chronic autoimmune thyroiditis in 1.74%, primary hypothyroidism in 0.96%, and nodular goiter in 2.57%. Peak prevalence of chronic autoimmune thyroiditis occurred in 2001-2003 i.e. in a period of their intensive pubertal maturation. In children (first generation) of exposed parents the thyroid dis ease was revealed in 42.64%, that exceeded the incidence in control group, chronic autoimmune thyroiditis was found rarer i.e. in 0.45%, diffuse non toxic goiter in 9.5-13.8%, nodular goiter in 1.7%. CONCLUSIONS: Non cancer endocrine disease in children and adults exposed to ionizing radiation is frequent and reg istered in 3 53% of persons. It occurs in most of survivors 10-15 years upon the impact of radiation factor as a result of man made accident and continues to grow slowly in 30 years.
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Waveform-stabilized laser pulses have revolutionized the exploration of the electronic structure and dynamics of matter by serving as the technological basis for frequency-comb and attosecond spectroscopy. Their primary sources, mode-locked titanium-doped sapphire lasers and erbium/ytterbium-doped fibre lasers, deliver pulses with several nanojoules energy, which is insufficient for many important applications. Here we present the waveform-stabilized light source that is scalable to microjoule energy levels at the full (megahertz) repetition rate of the laser oscillator. A diode-pumped Kerr-lens-mode-locked Yb:YAG thin-disk laser combined with extracavity pulse compression yields waveform-stabilized few-cycle pulses (7.7 fs, 2.2 cycles) with a pulse energy of 0.15 µJ and an average power of 6 W. The demonstrated concept is scalable to pulse energies of several microjoules and near-gigawatt peak powers. The generation of attosecond pulses at the full repetition rate of the oscillator comes into reach. The presented system could serve as a primary source for frequency combs in the mid infrared and vacuum UV with unprecedented high power levels.
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The results of clinical (200 patients) and experimental (30 dogs) studies reported by the authors show that lipid peroxidation in obstructive jaundice plays an essential role in hepatic functional and morphological abnormalities. Current examination methods were used which confirmed the well-known pathophysiological abnormalities in the body of patients with obstructive jaundice leading to marked hypoxia of hepatocytes and proved that lipid peroxidation is significantly intensified in a liver affected by subhepatic cholestasis. The authors suggest their own conception of the pathophysiological and biochemical shifts in the organism of a patient with obstructive jaundice which are capable of causing stimulation of lipid peroxidation and accumulation of highly toxic products of this process in the body. A scheme of prevention and treatment of hepatic insufficiency is suggested for practical surgery by antioxidants of direct and mediated action which were selected from a series of drugs currently in use.
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Antioxidantes/uso terapêutico , Colestase/tratamento farmacológico , Idoso , Animais , Colestase/metabolismo , Colestase/cirurgia , Cães , Feminino , Humanos , Peroxidação de Lipídeos , Masculino , Pessoa de Meia-IdadeRESUMO
The grounds for expediency of pancreatic resection in various periods of the necrotic pancreatitis clinical course are presented together with the description of a simplier technique of a left-side resection of the gland combined with spleenectomy. The left-side resection of the pancreas was carried out in 74 cases, pancreatoduodenal resection--in 1 patient. 4 patients died.
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Pancreatectomia/métodos , Pancreatite/cirurgia , Doença Aguda , Drenagem , Vesícula Biliar/cirurgia , Humanos , Necrose , Esplenectomia/métodosRESUMO
Histological and histochemical investigations of muscles in 18 patients have shown that when performing primary amputations of lower extremities according to the type of surgical treatment in the wound stump there necessarily remains muscular tissue of lower viability with necrotic areas.
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Cotos de Amputação , Glicogênio/metabolismo , Traumatismos da Perna/cirurgia , Músculos/metabolismo , Cicatrização , Humanos , Traumatismos da Perna/metabolismo , Retalhos CirúrgicosRESUMO
Objective. The study examined the morbidity pattern of non-cancer endocrine disease in ChNPP accident emergency workers (AEW) versus the entire population of Ukraine. Materials and methods. The study included a retrospective estimation of the examination data from 10,771 ChNPP AEW of the so-called iodine and non-iodine periods (main study group). Data were received from the RCRM Clinical/Epidemiological Registry for the survey period of 22 years (1992-2013) on persons been either healthy or having a range of endocrine disease. Anthropometric measures both with biochemical and hormonal assay data and external radiation dose values were taken into account. Diagnostic thyroid ultrasound was applied. Results. There is a significant (2-10-fold) and reliable (p < 0.01) increase of the incidence of non-cancer endocrine disease in the ChNPP AEW, namely by 23.20 % of nodular goiter (0.53 % in control, χ2 = 9602, Ñ < 0.0001), by 13.37 % of autoimmune thyroiditis (0.35 % in control; χ2 = 5381, Ñ < 0.0001), by 11.89 % in average and by 16.29 % in last years of type 2 diabetes mellitus (χ2 = 2527, Ñ < 0.0001), by 41.67 % of pre-obesity (χ2 = 10.92, Ñ < 0.01), and by 38.12 % of obesity (χ2 = 41.50, Ñ < 0.01) compared to the entire population. Conclusions. Effects of ionizing radiation and other hazardous factors on endocrine system in the ChNPP AEW appeared upon 15-25 years. There was a significant (2-10-fold) and reliable (p < 0.01) increase of the incidence of the nodular goiter, autoimmune thyroiditis, obesity, type 2 diabetes mellitus. And there is a trend to further increase.