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This work describes an experiment to demonstrate, for the first time, laser wakefield acceleration (LWFA), driven by 10.6-μm light from a CO2 laser. This experiment is also noteworthy because it will operate in a pseudoresonant LWFA regime, in which the laser-pulse-length is too long for resonant LWFA, but too short for self-modulated LWFA. Nonetheless, high acceleration gradients are still possible. This experiment builds upon an earlier experiment called staged electron laser acceleration (STELLA), where efficient trapping and monoenergetic laser acceleration of electrons were demonstrated using inverse free electron lasers. The aim is to apply the STELLA approach of laser-driven microbunch formation followed by laser-driven trapping and acceleration to LWFA. These capabilities are important for a practical electron linear accelerator based upon LWFA. [ABSTRACT FROM PUBLISHER]

Loss of heterozygosity (LOH) on chromosome 18q21 is frequently found in various human cancers, suggesting the presence of tumour suppressor gene(s) in this chromosomal region. DCC is the most likely target of LOH because loss or reduction of DCC expression has been found in many types of cancers. However, few reports have focused on sequence mutations of this gene. We investigated sequence mutations and expression of DCC in primary gastric cancers. We studied mutations in 25 of the 29DCC exons by PCR-SSCP in 17 primary gastric cancers exhibiting LOH on 18q21. No mutations of DCC were found in any of the tumours, although 78% (47/60) of the primary tumours showed apparent loss or reduction of DCC expression by immunohistochemistry. Analysis of methylation status of DCC revealed that methylation frequently occurred in both primary tumours (75%; 45/60) and corresponding non-cancerous gastric mucosae (72%; 43/60). Methylated status of DCC was significantly correlated with the loss of DCC expression in primary tumours (P < 0.01). These results indicate that DCC is frequently silenced, probably by epigenetic mechanisms instead of sequence mutations in gastric cancer. [ABSTRACT FROM AUTHOR]

A system for measuring the absorptance of mirrors at angles of incidence from 0° to >89° for both s- and p-polarized light is described. Photoacoustic calorimetry is used in which the piezoelectric transducer is directly attached to the back of the mirror substrate. Determination of absolute absorptance is performed using a laser energy ratiometer at near normal incidence. The procedure for accurately aligning the laser beam to the mirror surface is described, as well as a method to compensate for the transducer dependence on the laser beam footprint shape. This system has been used successfully to measure the absorptance characteristics of metal mirrors and dielectric overcoated metal mirrors at several laser wavelengths. Sample results are given. Other applications of this technique are discussed. [ABSTRACT FROM AUTHOR]

We present the autopsy case of an 82-year-old Japanese woman with a mucin-producing adenoma accompanied by pancreas divisum and a hepatic hilar carcinoma. She had suffered from a cholangiocellular carcinoma at the hepatic hilus for 2 months, which was treated with radiation and chemotherapy. She did not complain of any abdominal pain. Obstructive jaundice deteriorated despite percutaneous transhepatic bile duct drainage, and she died of hepatic insufficiency. At autopsy, a hepatic tumor was confirmed to have caused severe obstructive jaundice. Histological examinations showed moderately to poorly differentiated cholangiocellular adenocarcinoma with squamous metaplasia, probably due to radiation. A yellowish mucinous tumor was found in the head of the pancreas near the minor papilla. It consisted of multiple rice-sized cystic lesions with thin septa. Although it had no capsule, its margin was clear. Neither a wide opening of the major or minor papilla nor mucous drainage was observed. Gross examinations revealed unfused pancreatic ducts. The slightly dilatated dorsal duct and a branch of the mildly dilatated ventral duct showed tumor involvement. Histological examinations showed mild atypia of the epithelia, and this pancreatic tumor was diagnosed as branch duct-type mucin-producing adenoma with postradiation dysplasia. The combination of a mucin-producing tumor and pancreas divisum is rare, and this is only the third reported case. [ABSTRACT FROM AUTHOR]

Two cases of pancreatic cancer accompanied by pseudocyst are reported. Case 1 was a 60-year-old man who was admitted to our hospital complaining of left lower abdominal discomfort. A cystic lesion, about 3 cm in diameter, was found in the pancreatic tail by ultrasonography (US) and computed tomography (CT). No signs of chronic pancreatitis were found. At operation, an elastic, hard, white tumor, about 1 cm in diameter, was felt adjacent to the cystic lesion on the duodenal side. Histologically, this tumor was a duct cell carcinoma with an adjacent pseudocyst upstream of the pancreas. Case 2 was a 57-year-old man who complained of back pain and loss of body weight. US and CT examination revealed a cystic lesion, 11 x 7 cm in size, in the tail of the pancreas. Histological examination of the resected specimen revealed both a duct cell carcinoma, 3 cm in size, in the body of the pancreas and a pseudocyst, 9 cm in size. Pseudocysts accompanying carcinoma are thought to develop from obstruction of the pancreatic duct by the carcinoma, followed by intraductal high pressure and disruption of ductules upstream of the pancreas. Thus, we should pay careful attention to pseudocyst of the pancreas, especially when signs of diffuse chronic inflammation cannot be found, to help identify duct cell carcinoma in the early stage. Further detailed examinations of the cyst fluid or pancreatic juice, such as cytology, tumor marker determinations, or establishment of K-ras codon 12 mutation, are needed. [ABSTRACT FROM AUTHOR]

A CO2 quadrature interferometer is used to measure the temporal evolution of the electron density in XeF and KrF electron-beam-pumped laser mixtures (nonlasing). Measurements are obtained using a 300-kV electron beam which delivers >=10 A/cm2 at the foil for pulse durations ≤650 ns (FWHM). For typical XeF mixtures (99.35% Ne/0.5% Xe/0.15% F2 at 2888 Torr) the electron density varies between 3 and 4.5×1014 cm-3 during the pulse. The electron density is found to increase as the initial F2 concentration is decreased. Both 10% Kr in argon diluent and argon-free KrF mixtures are tested. The electron density for these mixtures has the same magnitude and behavior as the typical XeF mixture. [ABSTRACT FROM AUTHOR]

Time-dependent electron density measurements of electron beam pumped XeCl laser mixtures (nonlasing) are performed using a CO2 (10.6 μm) quadrature interferometer. The electron beam pulse length is ≊500 ns (full width at half-maximum) and delivers >=10 A/cm2 at the foil. Electron densities are measured as a function of the halogen (HCl) and xenon concentration. For a 99.3% Ne/1.5% Xe/0.16% HCl mixture at 3000 Torr, the electron density peaks near the beginning of the pulse at ≊7×1014 cm-3, decreases to 3×1014 cm-3, then gradually increases to ≊6×1014 cm-3 at the end of the pulse. As the initial halogen concentration is reduced, the electron density increases, rising dramatically near the end of the pulse. This increase in the electron density later in the pulse is accompanied by a decrease of the XeCl* sidelight fluorescence. [ABSTRACT FROM AUTHOR]