Treatment of anorexia nervosa

Although the histogenesis of meningeal hemangiopericytomas (HMP) remains controversial, both biological and clinical evidence seems to identify these neoplasms as a separate entity with respect to meningiomas. In order to assess the current prognosis of HMP we reviewed our personal experience limited to the last decade (1986-1995): during this period 7 patients (4M, 3F) were treated by surgery alone or surgery combined with postoperative radiotherapy. In spite of meticulous attempts at radical resection, the tumors recurred in all but two cases with a mean interval of 85 months, and a total of 18 operations were performed (2.57/patient; range 1-4). Massive intratumoral hemorrhage determined acute deterioration and required emergency surgery in two cases while in one patient diffuse visceral metastases were discovered at autopsy. Five patients are still alive at follow-up but only 2 of them are in good neurological conditions and without evidence of disease. These results are similar to those reported in other series. In view of our results we conclude that intracranial hemangiopericytomas still have a dismal prognosis. Advances in neuroimaging, neuroanesthesia, microneurosurgery and adjuvant therapy do not seem to have significantly affected the recurrence rate, quality of life and mortality.     

Chirping compensation using a two-section semiconductor laseramplifier

Compensation of light source chirping and optical fiber dispersion using semiconductor laser amplifiers (SLAs) is investigated using a modeling equation that describes the opposite phase characteristics of light sources to SLAs with self phase modulation. A two-section SLA was fabricated in order to achieve an amplifier with both high gain and phase compensation properties. Preliminary experimental results are presented, confirming the theoretically derived phase compensation effect     

Observation of field-induced refractive index variation in quantum box structure

An electric-field-induced refractive index variation in a GaInAs/InP five-layered quantum box structure was observed for the first time. The wavelength dependence of the refractive index variation was measured to confirm the quantum box effect. The size of the GaInAs/InP quantum box was estimated to be (22-30 nm)/sup 2/ with the thickness of 7.5 nm. from the spectral property of the field-induced refractive index variation. The maximum value of the refractive index variation in the quantum box was evaluated to be 7% around 1.52 mu m wavelength at an applied electric field of 8*10/sup 4/ V/Cm.<>     

Analysis of dynamic spectral width of dynamic-single-mode (DSM) lasers and related transmission bandwidth of single-mode fibers

A simple formula of the dynamic spectral width of a directly modulated dynamic-single-mode (DSM) laser, and the related maximum transmission bandwidth of a single-mode fiber limited by chromatic dispersion are theoretically given. The dynamic spectral width of a DSM laser is determined by the modulated optical shape and the linewidth enhancement factor α. The spectral width caused by the dynamic wavelength shift is shown to be larger by (1 + alpha^{2})^1/2than that caused by the sideband of the signal of the intensity modulation. Furthermore, the maximum transmission bandwidth of a conventional single-mode fiber with a DSM laser is expressed by using the parameter α and the chromatic dispersion of the fiber. The product of the maximum bit rate and the square root of the fiber length at the wavelength of 1.55 μm is estimated to be about 25 Gbit/s . km^1/2.     

Plausible guard effect on the active sites of heterogeneous Ziegler–Natta catalyst by coordinating monomers and growing polymer chains in the initial stage of propene polymerization

Investigation of propene polymerization by a modified stopped‐flow technique using TiCl₄/ethylbenzoate(EB)/MgCl₂ Ziegler–Natta catalyst with or without pretreating the catalyst with triethylaluminium (TEA) within an ultra‐short period (ca 1 s) was conducted to gain new understanding of the nature of active sites related to TEA in the early stage of polymerization. When the catalyst was pretreated by a cocatalyst, deactivation behaviour was clearly observed, even within an extremely short pretreatment period. In contrast, without pretreatment, the deactivation of active sites can be neglected within the polymerization period indicating that the activated Ti species might be protected from deactivation by TEA when monomer is present in the system. A plausible guard effect on the active sites by coordinating monomer and growing polymer chains in the initial stage of polymerization is proposed to account for this phenomenon. Copyright © 2004 Society of Chemical Industry     

A GaInAsP/InP tapered-waveguide semiconductor laser amplifierintegrated with a 1.5 μm distributed feedback laser

A GaInAsP/InP index-guided type tapered-waveguide traveling-wave semiconductor laser amplifier (TTW-SLA) with exponential taper structure was realized for the first time and its integration with a 1.5 μm wavelength phase adjusted DFB laser was demonstrated. A reasonable amount of the single-pass gain, which was limited by the residual reflectivity at the output end of the amplifier region, was obtained with no serious problem with the lasing spectrum. A narrow beam divergence of FWHM=5.5° and stable longitudinal mode operation were obtained with the output waveguide width of 20 μm by adopting both a window structure and 7° angled facets. This value agrees well with the theoretically calculated one and proves that single transverse-mode propagation can be attained by an exponentially tapered TTW-SLA with a very wide output end     

GaInAsP/InP integrated laser with butt-jointed built-in distributed-Bragg-reflection waveguide

A novel GaInAsP/InP integrated laser with butt-jointed built-in distributed-Bragg-reflection waveguide (BJB-DBR integrated laser for short) is proposed and demonstrated. In this structure, it is found theoretically that an efficient coupling of 98% between the active and butt-jointed external waveguides is available by matching the propagation constants and the field profiles of both waveguides, which gives relatively larger fabrication tolerance. Prototype BJB-DBR integrated lasers with emitting wavelength of 1.55 ?m were fabricated, and single-longitudinal-mode operation was obtained at room temperature.     

Single-wavelength operation of 1.53 ?m GaInAsP/InP buried-heterostructure integrated twin-guide laser with distributed Bragg reflector under direct modulation up to 1 GHz

1.53 ?m GaInAsP/InP buried-heterostructure integrated twin-guide laser with distributed Bragg reflector (BH-DBR-ITG laser) was directly modulated with microwave modulation current superimposed on a DC bias which was fixed at 1.1 times the threshold current, and single-wavelength operation was experimentally confirmed with a modulation frequency up to 1 GHz and a modulation depth of 100%.     

Polarization control on output of single-mode optical fibers

Polarization control of the light output from single-mode fiber systems is very important in order to connect it to polarization-dependent integrated optical circuits and applications using a heretodyne detection system. In this paper, automatic control of the polarization of light transmitted through the fiber was demonstrated by an electrooptical and electrical feedback system. In this system, we used a 1.6 μm long wavelength semiconductor CW BH laser, low-loss single-mode optical fiber with a loss of 0.2 dB/km, and two thinz-cut LiNbO3modulators tilted 45° relative to each other. The output light from this polarization controller was maintained to be linear while that from the single-mode fiber was unstable and elliptically polarized.     

岩石中主成分和微量成分X射线荧光分析的低稀释比玻璃融珠方法

采用ｍ样品：ｍ熔剂为１：２的低稀释比玻璃熔融技术，Ｘ射线荧光法测定岩石中的主成分和微量成分，既提高了灵敏度又不均质效应。与粉末压片方法相比，对硫的分析得到了更好的结果。同时，使用基本参数程序建立了一种新的校正方法来校正由于烧失量、烧增量、释释比或熔剂挥发而导致的分析误差。