Wavelength-independent operation of EA-modulator integratedwavelengthselectable microarray light sources

In this letter, we have simultaneously fabricated five wavelength-selectable microarray light sources (WSLs), each having a different wavelength range integrated with an electroabsorption (EA) modulator on a single wafer. We also introduced a novel device configuration scheme for wavelength-independent modulation. The five EA-WSLs fully covered the entire C-band and had a low uniform threshold current of 6 ± 1 mA at 25°C. Wavelength-independent extinction characteristics were obtained over a tuning wavelength range of 8 nm, and 2.5-Gb/s transmission over 600 km was successfully achieved     

Retroviral transfer of CPP32beta gene into malignant gliomas in vitro and in vivo

Malignant gliomas are highly aggressive neoplasms that are very resistant to current therapeutic approaches, including irradiation, chemotherapy, and immunotherapy. To improve the prognosis, it is absolutely essential to explore novel modalities of treatment. Recently, we have demonstrated that interleukin 1beta-converting enzyme (ICE), a mammalian homologue of the Caenorhabditis elegans cell death gene ced-3, induces apoptotic cell death in malignant glioma cells. To date, ICE and ICE-like proteases (the ICE family), such as Ich-1L, CPP32beta, Mch2alpha, and Mch3alpha, have been shown to mediate apoptosis in some cells. The purpose of this study is to determine whether the ICE gene family functions as a useful tool for the treatment of malignant glioma cells through induction of apoptosis. The transient transfection assays showed that CPP32beta and Mch2alpha genes induced apoptotic cell death in malignant glioma cells more effectively than did the ICE, Ich-1L, and Mch3alpha genes. To improve the efficiency of gene transfer into malignant glioma cells, we constructed the retroviral vectors containing the ICE gene family. The retroviral transfer of CPP32beta or Mch2alpha gene effectively induced apoptosis in malignant glioma cells in vitro. Furthermore, treatment of tumors grown in mice with retrovirus containing CPP32beta significantly inhibited growth of the tumors through induction of apoptosis. The retroviral transfer of CPP32beta or Mch2alpha, therefore, may be a novel and promising approach for the treatment of malignant glioma, an invariably fatal tumor.     

Partial renal embolization for pediatric renovascular hypertension secondary to fibromuscular dysplasia

We report a 7-year-old boy with renovascular hypertension showing multiple stenoses and microaneurysms of the dorsal branch of the left renal artery caused by fibromuscular dysplasia. Hypertension was successfully treated with transcatheter alcohol and gelatin sponge embolization of the dorsal branch and its distribution. The vertebral branch remained intact. No severe complication was encountered. Loss of renal function by renal scintigraphy was minimal. The patient remains asymptomatic at 1 year.     

Modulator integrated DFB lasers with more than 600-km transmission capability at 2.5 Gb/s

The modulator integrated DFB laser diodes with more than 600-km transmission capability over normal fiber at 2.5 Gb/s, have been reproducibly achieved. The longest transmission length obtained in the experiment is as long as 800 km.     

Effect of a catalyst on heterogeneous nucleation in pure and Fe-Ni alloys

In order to elucidate the nature of the heterogeneous nucleation, a differential scanning calorimetry (DSC) thermal analysis of pure Fe and Fe-Ni alloys (Ni content: 1.0 to 29.3 mass pct) containing TiN, Al₂O₃, and Ti₂O₃ was conducted. Then, special attention was paid to the difference in the phase of the primary crystal nucleated by the triggering effect of a catalyst (nucleating agent). The solidification and transformation mode appearing during cooling in these alloys is classified into three cases: F mode, FA mode, and A mode. The change of modes and the critical undercooling (ΔT) depend on the kind of catalyst used as well as the chemical composition (Ni content). In addition, in spite of the kind of primary crystal, the value of ΔT is always small in the order of TiN, Al₂O₃, and Ti₂O₃. As a matter of fact, only TiN has a practical effect as a catalyst on the triggered nucleation of the primary crystal of the δ phase. None of them has a practical effect on the nucleation of the primary crystal of the γ phase. This article is based on a presentation given in the Mills Symposium entitled “Metals, Slags, Glasses: High Temperature Properties & Phenomena,” which took place at The Institute of Materials in London, England, on August 22–23, 2002.     

An in situ field-ion microscope research of radiation damage in tungsten

Results of experiments in which tungsten was irradiated in situ in the field-ion microscope with inert gas ions are described. Tungsten field-ion specimens were irradiated at 78 K with ions in the 0.5–9 keV energy range. Sputtering and displacement of surface atoms which had occurred during irradiation were observed directly in field-ion images. Large scale damage such as vacancy clusters were rarely found. From the ion acceleration voltage and the accommodation coefficient, the displacement energy of tungsten surface atoms in the electric field of about 44 MV/mm is estimated as nearly 22 eV. Damage was observed on the shielded side of the tip apex as well as on the ion incident side, and this fact is discussed in comparison with the channelling of ions in tungsten.     

Real-time monitoring system of tool breakage using Kalman filtering

In this paper, a real-time monitoring system of tool breakage, which measures the cutting torque from the spindle motor current, is described. The system uses an auto-regressive (AR)-model which is adapted for the measured signal using the Kalman filtering technique. The tool breakage is detected by monitoring the residual, that is, the deviation of the observed signal from the estimated value obtained by the AR-model. Additional processing of the residual is introduced to discriminate the signature of tool breakage from the effect caused by the marked change in the cutting condition. To reduce the computation time, the fast calculation algorithm is adopted for estimating the coefficient vector of the AR-model. The monitoring experiment has proven the effectiveness of the system in a milling operation.     

Regulation and mechanisms of gene amplification

Amplification in rodent cells usually involves bridge-breakage-fusion (BBF) cycles initiated either by end-to-end fusion of sister chromatids, or by chromosome breakage. In contrast, in human cells, resistance to the antimetabolite N-(phosphonacetyl)-L-aspartate (PALA) can be mediated by several different mechanisms that lead to overexpression of the target enzyme carbamyl-P synthetase, aspartate transcarbamylase, dihydro-orotase (CAD). Mechanisms involving BBF cycles account for only a minority of CAD amplification events in the human fibrosarcoma cell line HT 1080. Here, formation of a 2p isochromosome and overexpression of CAD by other types of amplification events (and even without amplification) are much more prevalent. Broken DNA is recognized by mammalian cells with intact damage-recognition pathways, as a signal to arrest or to die. Loss of these pathways by, for example, loss of p53 or pRb tumour suppressor function, or by increased expression of ras and myc oncogenes, causes non-permissive rat and human cells to become permissive both for amplification and for other manifestations of DNA damage. In cells that are already permissive, amplification can be stimulated by overexpressing oncogenes such as c-myc or ras, or by damaging DNA in a variety of ways. To supplement genetic analysis of amplification in mammalian cells, an amplification selection has been established in Schizosaccharomyces pombe. Selection with LiCl yields cells with amplified sod2 genes in structures related to those observed in mammalian cells. The effect on amplification in S. pombe can now be tested for any mutation in a gene involved in repair of damaged DNA or in normal cellular responses to DNA damage.     

Gas and vapor permeability of perfluoroalkylated polymers

Summary Three polymers bearing benzene rings: polystyrene, poly(2,6-dimethyl-p-phenylene oxide) and poly(diphenylacetylene), were chemically modified with bis(heptafluorobutyryl) peroxide. The heptafluoropropylated products have higher gas permeabilities than the parent polymers. In the pervaporation of aqueous ethanol, modified poly(diphenylacetylene) showed ethanol permselectivity.