SECTION ON MATHEMATICS (A) AND AFFILIATED SOCIETY     

Hedrick ER  Baylis CA 《Science (New York, N.Y.)》1941,93(2406):124-125

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Inbreeding and evolution     

Hedrick P 《Science (New York, N.Y.)》1994,263(5143):107-108

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Diagnosis of sturgeon iridovirus infection in farmed white sturgeon in British Columbia          下载免费PDF全文

Raverty S  Hedrick R  Henry J  Saksida S 《The Canadian veterinary journal. La revue veterinaire canadienne》2003,44(4):327-328

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Mortality and recovery of runt white sturgeon (Acipenser transmontanus) in a commercial farm in California, USA     

Georgiadis MP  Hedrick RP  Johnson WO  Gardner IA 《Preventive veterinary medicine》2000,43(4):269-281

We investigated the effect of raising runt white sturgeon (Acipenser transmontanus) separately from dominant fish during the initial stages of grow-out in a commercial farm. Runt fish are poor-growers, have underdeveloped muscle mass, swim slowly and are more-frequently found at the top of the water column. The objective of the study was to describe the mortality and recovery rates (and their determinants) of white-sturgeon runts after separating them from dominant fish. Runt white sturgeon were stocked into twelve 2 m × 2 m rectangular tanks and graded periodically during a follow-up of 46–102 days. Overall mortality rates ranged from 0.3 to 7 dead fish per 1000 sturgeon-days at risk and overall recovery rates from 3.9 to 13.5 recovered fish per 1000 sturgeon-days at risk. Period-specific mortality and recovery rates increased over time. The period-specific mortality rates for all three periods were significantly higher for tanks of runts originating from grow-out tanks with high mortality (p-values: first period = 0.06; second period = 0.09; third period = 0.03), but were similar for tanks of runts of high- and low-mean initial weight. The period-specific recovery rates were significantly higher in runts originating from high-mortality grow-out tanks only for the third period (p = 0.05) but not the first and second periods (p-values = 0.33 and 0.25, respectively). Recovery rates were significantly higher in the higher-mean-weight runts tanks for the first and third period but not for the second (p-values: first period = 0.02; second period = 0.65; third period = 0.06). We concluded that the proportion of runts that recover during a 46–89 day period is substantial (16–58%); therefore, it might be worthwhile growing such fish separately in a fish farm for about three months. Financial analysis showed that this practice was profitable, if the value of white sturgeon fish for the farm exceeded $2.05 per kg.  相似文献   

MULTIPLICITY OF CROPS AS A MEANS OF INCREASING THE FUTURE FOOD SUPPLY     

Hedrick UP 《Science (New York, N.Y.)》1914,40(1035):611-620

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CONCERNING THE ARTICLE "A NEW GRAPHIC ANALYTIC METHOD     

Roever WH  Hedrick ER 《Science (New York, N.Y.)》1922,55(1424):401-405

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Nodavirus infection of juvenile white seabass, Atractoscion nobilis, cultured in southern California: first record of viral nervous necrosis (VNN) in North America     

P A Curtis  M Drawbridge  T Iwamoto  T Nakai  R P Hedrick  & A P Gendron 《Journal of fish diseases》2001,24(5):263-271

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Measurement of conchal atrophy and pneumonic lesions and their association with growth rate in commingled feeder pigs     

R P Cowart  R J Lipsey  H B Hedrick 《Journal of the American Veterinary Medical Association》1990,196(8):1262-1264

A group of 85 commingled feeder pigs was fed on a totally confined feeding floor until slaughter. Mean daily weight gain was calculated for each pig. At slaughter, the nose of each pig was cross-sectioned and scored for conchal atrophy by use of 2 methods. One method ascribed a score based on a linear measurement of the distance between the ventral scroll of the ventral conchae and the ventral floor of the nasal cavity. The other method ascribed a score based on a subjective evaluation of the degree of conchal degeneration according to previously published guidelines. The amount of pulmonary consolidation attributable to pneumonia was also estimated for each pig. Association was not found between growth rate and conchal atrophy, as determined by linear measurement scores. A negative correlation existed between growth rate and conchal atrophy, as determined by subjective evaluation scores. Pigs with extensive pneumonic lesions (consolidation of 20 to 30% of total lung volume) grew slower than pigs with milder pneumonic lesions. Results of this study indicate that subjective evaluation scores of conchal atrophy may be more useful in predicting growth rate than are linear measurement scores.  相似文献   

A heterozygote advantage     

Hedrick PW 《Science (New York, N.Y.)》2003,302(5642):57

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"Coulomb Staircase" at Room Temperature in a Self-Assembled Molecular Nanostructure     

RP Andres  T Bein  M Dorogi  S Feng  JI Henderson  CP Kubiak  W Mahoney  RG Osifchin  R Reifenberger 《Science (New York, N.Y.)》1996,272(5266):1323-1325

Double-ended aryl dithiols [alpha,alpha'-xylyldithiol (XYL) and 4,4'-biphenyldithiol] formed self-assembled monolayers (SAMs) on gold(111) substrates and were used to tether nanometer-sized gold clusters deposited from a cluster beam. An ultrahigh-vacuum scanning tunneling microscope was used to image these nanostructures and to measure their current-voltage characteristics as a function of the separation between the probe tip and the metal cluster. At room temperature, when the tip was positioned over a cluster bonded to the XYL SAM, the current-voltage data showed "Coulomb staircase" behavior. These data are in good agreement with semiclassical predictions for correlated single-electron tunneling and permit estimation of the electrical resistance of a single XYL molecule (approximately18 ± 12 megohms).  相似文献