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At least 901 records · Page 50Linked to original sources
PubMed2003

Abundance estimation from multiple photo surveys: confidence distributions and reduced likelihoods for bowhead whales off Alaska.

Maximum likelihood estimates of abundance are obtained from repeated photographic surveys of a closed stratified population with naturally marked and unmarked individuals. Capture intensities are assumed log-linear in stratum, year, and season. In the chosen model, an approximate confidence distribution for total abundance of bowhead whales, with an accompanying likelihood reduced of nuisance parameters, is found from a parametric bootstrap experiment. The confidence distribution depends on the assumed study protocol. A confidence distribution that is exact (except for the effect of discreteness) is found by conditioning in the unstratified case without unmarked individuals.

Aging↗
PubMed1998

Alaska nurse practitioners' and physician assistants' perceptions of the collaboration process.

In summary, the findings suggest that NPs and PAs have a common perception of the collaboration process, and most participants engaged in more collaborative behaviors rather than less. The results can serve as an introduction to studying collaborative interactions between NPs and PAs. Such collaborative efforts have the potential to optimize patient care and increase respect, trust, and communication between the two professions.

Adult↗
PubMed2000

Periodontal disease in American Indians and Alaska Natives.

OBJECTIVE: The primary purpose of this paper is to provide information on the periodontal disease status of Native Americans using a variety of data sources. The impact of periodontal disease on the provision of dental care within the Indian Health Service (IHS) is also discussed. METHODS: Four data sources were used to evaluate the periodontal disease status of Native Americans: IHS periodontal disease monitoring system (1962-78), 1984 IHS Patient Oral Health Survey, 1990 WHO community-based survey (ICS-II), and the 1991 IHS Patient Oral Health Survey. RESULTS: There appears to be a trend toward a higher prevalence of incipient and overt periodontal disease among Native Americans over time. The prevalence of overt periodontal disease (periodontal pockets > 5.5 mm) is higher among Native American diabetic patients than nondiabetic patients (34% vs 19%). CONCLUSIONS: Due to the variety of indices used by the IHS during the last 20 years, it is difficult to make direct comparisons of the available periodontal disease data. However, it appears that the prevalence of periodontal disease among Native Americans is increasing. Type II diabetes accounts for significant increases in periodontal disease and tooth loss in Native American populations. Certain forms of early onset periodontal disease also may pose significant threats to the oral health of Native Americans.

Adult↗
PubMed1985

Passive acoustic location of bowhead whales in a population census off Point Barrow, Alaska.

A sonobuoy array placed in the nearshore lead was used for locating bowhead whale sounds to determine if whales migrated past census stations beyond visual range and were uncounted. Based on a sample of 182 whale sounds (over 48 h) from closest point of approach (CPA) distances out to more than 10 km, 68% originated beyond 2 km (CPA), where only 1% of the 242 whales were sighted. No whales were sighted beyond 3 km during this time, but 53% of the located sounds originated that far and beyond. Thirty-seven other bowhead sounds over 15 h were distributed out to 6 km. Two tracked whales moved at average speeds of 1.5 and 1.8 kn. Maximum location error was 1%-25% in a sector of 120 degrees X 5-10 km, depending upon bearing and range. Most whale sounds were low-frequency moans, trumpeting roars, and repetitive sequences (songs) with peak spectrum source level up to 189 dB re: 1 microPa, 1 m. Lack of correlations between numbers of sounds and sighted whales precluded using bowhead sounds to count individuals or even to extrapolate ratios of unseen to observed whales.

Alaska↗
PubMed1987

Sounds and source levels from bowhead whales off Pt. Barrow, Alaska.

Sounds were recorded from bowhead whales migrating past Pt. Barrow, AK, to the Canadian Beaufort Sea. They mainly consisted of various low-frequency (25- to 900-Hz) moans and well-defined sound sequences organized into "song" (20-5000 Hz) recorded with our 2.46-km hydrophone array suspended from the ice. Songs were composed of up to 20 repeated phrases (mean, 10) which lasted up to 146 s (mean, 66.3). Several bowhead whales often were within acoustic range of the array at once, but usually only one sang at a time. Vocalizations exhibited diurnal peaks of occurrence (0600-0800, 1600-1800 h). Sounds which were located in the horizontal plane had peak source spectrum levels as follows--44 moans: 129-178 dB re: 1 microPa, 1 m (median, 159); 3 garglelike utterances: 152, 155, and 169 dB; 33 songs: 158-189 dB (median, 177), all presumably from different whales. Based on ambient noise levels, measured total propagation loss, and whale sound source levels, our detection of whale sounds was theoretically noise-limited beyond 2.5 km (moans) and beyond 10.7 km (songs), a model supported by actual localizations. This study showed that over much of the shallow Arctic and sub-Arctic waters, underwater communications of the bowhead whale would be limited to much shorter ranges than for other large whales in lower latitude, deep-water regions.

Alaska↗
PubMed2000

Calibration and comparison of the acoustic location methods used during the spring migration of the bowhead whale, Balaena mysticetus, off Pt. Barrow, Alaska, 1984-1993.

Between 1984 and 1993, visual and acoustic methods were combined to census the Bering-Chukchi-Beaufort bowhead whale, Balaena mysticetus, population. Passive acoustic location was based on arrival-time differences of transient bowhead sounds detected on sparse arrays of three to five hydrophones distributed over distances of 1.5-4.5 km along the ice edge. Arrival-time differences were calculated from either digital cross correlation of spectrograms (old method), or digital cross correlation of time waveforms (new method). Acoustic calibration was conducted in situ in 1985 at five sites with visual site position determined by triangulation using two theodolites. The discrepancy between visual and acoustic locations was <1%-5% of visual range and less than 0.7 degrees of visual bearing for either method. Comparison of calibration results indicates that the new method yielded slightly more precise and accurate positions than the old method. Comparison of 217 bowhead whale call locations from both acoustic methods showed that the new method was more precise, with location errors 3-4 times smaller than the old method. Overall, low-frequency bowhead transients were reliably located out to ranges of 3-4 times array size. At these ranges in shallow water, signal propagation appears to be dominated by the fundamental mode and is not corrupted by multipath.

Acoustics↗
PubMed1962

Strontium-90 in Alaska.

Strontium-90 concentrations have been determined in a variety of foods used by the native population. Caribou from the tundra carry 10 to 20 times the level of domestic cattle. Eskimos for whom caribou is a staple in the diet are found to have four times the strontium-90 content of the average for the world population of the North Temperate Zone.

Alaska↗