Ocean bottom seismometer: design and test of a measurement system for marine seismology.

The Ocean Bottom Seismometer (OBS) is a key instrument for the geophysical study of sea sub-bottom layers. At present, more reliable autonomous instruments capable of recording underwater for long periods of time and therefore handling large data storage are needed. This paper presents a new Ocean Bottom Seismometer designed to be used in long duration seismic surveys. Power consumption and noise level of the acquisition system are the key points to optimize the autonomy and the data quality. To achieve our goals, a new low power data logger with high resolution and Signal-to-Noise Ratio (SNR) based on Compact Flash memory card is designed to enable continuous data acquisition. The equipment represents the achievement of joint work from different scientific and technological disciplines as electronics, mechanics, acoustics, communications, information technology, marine geophysics, etc. This easy to handle and sophisticated equipment allows the recording of useful controlled source and passive seismic data, as well as other time varying data, with multiple applications in marine environment research. We have been working on a series of prototypes for ten years to improve many of the aspects that make the equipment easy to handle and useful to work in deep-water areas. Ocean Bottom Seismometers (OBS) have received growing attention from the geoscience community during the last forty years. OBS sensors recording motion of the ocean floor hold key information in order to study offshore seismicity and to explore the Earth's crust. In a seismic survey, a series of OBSs are placed on the seabed of the area under study, where they record either natural seismic activity or acoustic signals generated by compressed air-guns on the ocean surface. The resulting data sets are subsequently used to model both the earthquake locations and the crustal structure.

Appropriateness of testicular cancer management: a population-based cohort study.

OBJECTIVE: Testicular cancer is a highly curable malignancy of young men. Appropriate and timely management is critical to ensure optimal clinical outcomes. A 3-year population-based review of testicular cancer patients in Manitoba, Canada was undertaken to evaluate our management patterns. METHODS: Men diagnosed with testicular cancer from 1998 to 2000 were identified from the Provincial Cancer Registry. Chart review was utilized to collect information on demographic characteristics, timelines of diagnostic and staging investigations, completeness of pathology reports, management, and outcomes. RESULTS: Seventy-eight men were identified with 80 testicular cancers: 46 (59%) patients had 48 seminomas and 32 (41%) had non-seminomatous germ cell tumors (NSGCT). One or more pre-operative tumor markers were missing or unavailable in 41 (52%) cases. Median time from scrotal ultrasound to orchiectomy was 7 days, but was greater than 2 weeks in 13 (16%) patients. Pathology reports provided acceptable detail in only 21 (27%) cases. Eighteen subjects (23%) did not complete necessary staging investigations (chest and abdominal imaging, and post-orchiectomy markers) until at least 3 weeks after surgery. Post-orchiectomy management of both seminoma and NSGCT patients was largely within acceptable limits apart from some non-standard chemotherapy choices in advanced stage disease, and significant departures from standard recommendations regarding surveillance. The Kaplan-Meier estimate of overall survival at 5 years is 97% in seminoma and 84% in NSGCT. CONCLUSIONS: Although clinical outcomes do not appear to have been compromised, deficiencies are evident in testicular cancer management in Manitoba from 1998 to 2000, indicating the need for well-defined management guidelines and improved education of caregivers.

Illicit drug-related harm during the Sydney 2000 Olympic Games: implications for public health surveillance and action.

AIMS: To describe presentations to emergency departments during the Sydney 2000 Olympic Games for conditions related to the use of illicit drugs; to discuss the implications of such presentations for surveillance and public health action at similar events in the future. DESIGN: Identification of target presentations in sentinel emergency departments; entry of data into a purpose-built database; and daily electronic transfer of data for central collation and analysis. SETTING: Fifteen sentinel emergency departments in the greater Sydney metropolitan area for a 38-day period spanning the Sydney 2000 Olympic Games. PARTICIPANTS: Four hundred and twenty-four presentations to sentinel emergency departments with conditions related to illicit drug use. MEASUREMENTS: Patient's age, sex, country and region of residence, location of emergency department, types of illicit drugs involved and departure status. FINDINGS: The mean daily number of presentations for adverse events due to illicit drug use was significantly higher (13.3 versus 8.8 presentations, t = 2.2, P = 0.04) in the 2-week Olympic Games period than in the lead-up to the Games, culminating in a large peak following the closing ceremony. There was also a significant increase (5.1 versus 1.7 presentations, t = 2.8, P = 0.007) in the mean daily number of presentations related to use of ecstasy or amphetamines, whereas no change was noted in presentations related to heroin use. Over half (52%) of presentations occurred at two emergency departments in areas known as being 'hot-spots' for illicit drug use. CONCLUSIONS: Enhanced surveillance of adverse events following illicit drug use, possibly targeting known 'hot-spots', should be considered for future mass events. Advance preparation of preventive strategies, such as 'party-safe' messages, will enable rapid response to unusual patterns of illicit drug-related harm during future mass events.