Passively mode-locked 914-nm Nd:YVO4 laser.

We demonstrate what is to our knowledge the first mode-locked Nd:YVO4 laser operating on the 4F3/2-4I9/2 transition at 914 nm. Using a semiconductor saturable-absorber mirror for passive mode locking, we have obtained 3-ps pulses at a repetition rate of 233.8 MHz. The laser is based on a standard delta cavity and is pumped by a Ti:sapphire laser. We obtained an average output power of 42 mW through one mirror and an accumulated output power of approximately 150 mW (through all cavity mirrors) at a pump power of 1.4 W.

Compact 10-GHz Nd:GdVO4 laser with 0.5-W average output power and low timing jitter.

We demonstrate a compact, diode-pumped Nd:GdVO4 laser with a repetition rate of 9.66 GHz and 0.5-W average output power. The laser is passively mode locked with a semiconductor saturable absorber mirror (SESAM), yielding 12-ps-long sech2-shaped pulses. For synchronization of the pulse train to an external reference clock, the SESAM is mounted on a piezoelectric transducer. With an electronic feedback loop of only a few kilohertz loop bandwidth we achieved a rms timing jitter of 146 fs (integrated from 10 Hz to 10 MHz). This is an upper limit because it is mostly limited by the measurement system. The laser setup with a simple linear cavity has a footprint of only 130 mm x 30 mm.

Development of prostate cancer after pituitary dysfunction: a report of 8 patients.

OBJECTIVES: Eight patients with a history of pituitary dysfunction were seen in the Department of Radiation Oncology at the Hospital of the University of Pennsylvania for evaluation of their prostate carcinoma. Because prostate cancer is a hormonally responsive cancer, hormonal abnormalities from pituitary dysfunction may have played a role in its development. In addition, many patients with pituitary dysfunction receive exogenous hormonal replacement. The histories of these 8 patients were reviewed to look for any common underlying factor in the development of their prostate cancer. METHODS: The radiation oncology charts, hospital charts, and pathology reports were reviewed. The cause and treatment of the pituitary disorder were reviewed. Hormonal dysfunction, hormonal replacement, and treatment duration were recorded. The interval to the development of prostate cancer, stage at diagnosis, prostate-specific antigen level, Gleason score, treatment, and treatment outcome were also investigated. RESULTS: We found a variety of pituitary disorders and treatments. However, all patients received testosterone replacement therapy prior to the development of their prostate cancer (median of 30 months). The time to the development of the cancer ranged from 26 to 250 months (median 98). Patients had Stage T2 or T3 tumors at diagnosis. Patients were treated either with radical prostatectomy or radiation therapy. Six of the 8 patients were alive and doing well at their last follow-up examination. CONCLUSIONS: Prostate cancer has been shown to be androgen responsive. All the patients in this series were placed on physiologic testosterone replacement for pituitary dysfunction. The role of testosterone in the initiation of prostate cancer has been debated. However, at the present time, it seems appropriate to establish close monitoring for prostate cancer in patients receiving androgen therapy for pituitary dysfunction.

Surface analysis by scanning electrochemical microscopy: resolution studies and applications to polymer samples.

Resolution studies of scanning electrochemical microscopy (SECM) have been performed in the feedback mode and in the generator/collector mode at circular model structures. A quantitative correlation of the loss in resolution and the increase in distance between tip and sample is found. Measuring a band electrode of just 500 nm width, the high sensitivity of the SECM in identifying chemically active sites is proven. Applied to polymer samples, the chemical composition was determined in the feedback mode at high lateral resolution. The difference in electrical conductivity allows one to distinguish between doped and undoped parts of a polyaniline film. By scanning above a blend consisting of polypyrrole and polypropylene, a map of the local chemical composition was obtained. In this context, the influence of the tip overpotential on the image is discussed.