A STUDY IN BIOKINETICS     

Snyder CD 《Science (New York, N.Y.)》1931,74(1923):443-449

In the foregoing pages the writer has attempted to point out first, the importance to physiologists of the discovery and application to their problems of a unit of physiological activity to serve as a universal measure of life processes. Second, a survey of the field of excitation and response points to the probability that electron transfers are involved in every case and, therefore, that such a standard of measure, if ever determined, will probably involve terms of radiational units. Third, a brief statement of some of the laws of radiation that seem to be involved is given, together with a sketch of the radiation hypothesis of chemical thermal reaction. Fourth, an analysis of the data of a few physiological processes is then presented, the results of which strongly suggest the possibility that the influence of temperature upon living processes may be due to dark-field radiations quite as much as the photochemical effects in living processes are due to radiation of visible light.  相似文献   

Regulation of gene expression by a metabolic enzyme     

Hall DA  Zhu H  Zhu X  Royce T  Gerstein M  Snyder M 《Science (New York, N.Y.)》2004,306(5695):482-484

  相似文献   

Brain histamine: rapid apparent turnover altered by restraint and cold stress   总被引：1，自引：0，他引：1  

K M Taylor  S H Snyder 《Science (New York, N.Y.)》1971,172(987):1037-1039

Histamine content of rat brain was lowered quickly by inhibitors of histidine decarboxylase, suggesting that a portion of brain histamine turns over rapidly. Restraint and exposure to cold also reduced brain histamine levels and markedly augmented its formation in the hypothalamus.  相似文献   

Dynamic plant uptake model applied for drip irrigation of an insecticide to pepper fruit plants   总被引：1，自引：0，他引：1  

Legind CN  Kennedy CM  Rein A  Snyder N  Trapp S 《Pest management science》2011,67(5):521-527

BACKGROUND: Drip application of insecticides is an effective way to deliver the chemical to the plant that avoids off‐site movement via spray drift and minimizes applicator exposure. The aim of this paper is to present a cascade model for the uptake of pesticide into plants following drip irrigation, its application for a soil‐applied insecticide and a sensitivity analysis of the model parameters. RESULTS: The model predicted the measured increase and decline of residues following two soil applications of an insecticide to peppers, with an absolute error between model and measurement ranging from 0.002 to 0.034 mg kg fw^?1. Maximum measured concentrations in pepper fruit were approximately 0.22 mg kg fw^?1. Temperature was the most sensitive component for predicting the peak and final concentration in pepper fruit, through its influence on soil and plant degradation rates. CONCLUSION: Repeated simulations of pulse inputs with the cascade model adequately describe soil pesticide applications to an actual cropped system and reasonably mimic it. The model has the potential to be used for the optimization of practical features, such as application rates and waiting times between applications and before harvest, through the integrated accounting of soil, plant and environmental influences. Copyright © 2011 Society of Chemical Industry  相似文献   

RELATION OF SEVERAL PEDOLOGICAL CHARACTERISTICS TO ENGINEERING QUALITIES OF SOIL   总被引：2，自引：0，他引：2  

D. DE LA  ROSA 《European Journal of Soil Science》1979,30(4):793-799

An attempt to predict engineering qualities which are needed in soil evaluation and to enhance nonagricultural use of soil survey data was made. Data from a variety of soils were subjected to simple correlation and multiple regression analyses to relate three pedologic characteristics: clay content, cation-exchange capacity (CEC), and organic matter content to two engineering qualitites: plasticity index, and optimum moisture. Simple correlation coefficients showed that clay content and CEC correlated significantly with the engineering determinations. The relationship between organic matter content and these engineering determinations was weaker. Multiple regression analyses showed that the three pedologic characteristics accounted for most of the variation in each of the engineering qualities, and that prediction was feasible.  相似文献   

Role of calcium in activating soybean lipoxygenase 2   总被引：3，自引：0，他引：3  

G L Zimmerman  H E Snyder 《Journal of agricultural and food chemistry》1974,22(5):802-805

  相似文献   

Finite element modeling of ROPS in static testing and rear overturns     

Harris JR  Mucino VH  Etherton JR  Snyder KA  Means KH 《Journal of agricultural safety and health》2000,6(3):215-225

Even with the technological advances of the last several decades, agricultural production remains one of the most hazardous occupations in the United States. Death due to tractor rollover is a prime contributor to this hazard. Standards for rollover protective structures (ROPS) performance and certification have been developed by groups such as the Society of Automotive Engineers (SAE) and the American Society of Agricultural Engineers (ASAE) to combat these problems. The current ROPS certification standard, SAE J2194, requires either a dynamic or static testing sequence or both. Although some ROPS manufacturers perform both the dynamic and static phases of SAE J2194 testing, it is possible for a ROPS to be certified for field operation using static testing alone. This research compared ROPS deformation response from a simulated SAE J2194 static loading sequence to ROPS deformation response as a result of a simulated rearward tractor rollover. Finite element analysis techniques for plastic deformation were used to simulate both the static and dynamic rear rollover scenarios. Stress results from the rear rollover model were compared to results from simulated static testing per SAE J2194. Maximum stress values from simulated rear rollovers exceeded maximum stress values recorded during simulated static testing for half of the elements comprising the uprights. In the worst case, the static model underpredicts dynamic model results by approximately 7%. In the best case, the static model overpredicts dynamic model results by approximately 32%. These results suggest the need for additional experimental work to characterize ROPS stress levels during staged overturns and during testing according to the SAE standard.  相似文献   

Assessment of Water Quality in Association with Land use in the Tillamook Bay Watershed, Oregon, USA     

Timothy J. Sullivan  Kai U. Snyder  Erin Gilbert  Joseph M. Bischoff  Mark Wustenberg  James Moore  Deian Moore 《Water, air, and soil pollution》2005,161(1-4):3-23

The water quality in tributaries to Tillamook Bay, Oregon, frequently exceeds standards for fecal coliform bacteria (FCB) and temperature. FCB inputs to the bay have forced periodic closure of the oyster shellfish industry. In addition, impaired water quality may be contributing to reduced salmonid populations in the bay and its tributaries through reduction in the quality of the habitat. Because of these concerns, the Tillamook Bay National Estuary Project (TBNEP) conducted several characterization studies and a long-term water quality monitoring program for the tributary rivers. This paper summarizes data collected to date within these efforts, including storm-based data on FCB and total suspended solids (TSS), and bimonthly data on nutrient concentrations in selected rivers. Monitoring data from 1996 to 2002 are summarized. Results for FCB and TSS are reported by storm, which are classified according to season and precipitation patterns in order to minimize intra-annual variability. There are not indications of large changes in water quality throughout the period of record, but it is too early in the program for trends analysis. Storms that exhibited the highest FCB concentrations tended to be those that occurred during fall and/or those that were preceded by relatively dry conditions and included high rainfall intensity. Implementation of storm-based monitoring and classification of storms according to season effectively reduces the large variability inherent in the FCB monitoring data, thereby facilitating future trends analysis. Continued storm-based monitoring of FCB and TSS, and also continued collection of rainfall and river discharge data, will provide the database that will be needed to determine to what extent on-the-ground remediation actions and best management practices (BMPs) within the Tillamook Basin are having their desired effects.  相似文献   

Subchondral bone cysts with fractures of the extensor processes in a horse.   总被引：1，自引：0，他引：1  

E A Scott  S P Snyder  W B Schmotzer  R Pool 《Journal of the American Veterinary Medical Association》1991,199(5):595-597

Probable cause of fracture in a Paint gelding was a congenital bone defect involving the extensor process area of the right and left forelimb distal phalanges. Radiographically and histologically, subchondral bone cysts at the fracture lines were suspected. These cysts were thought to have developed in association with abnormal ossification centers at the extensor process areas of the third phalanx. Partial avulsion of weak extensor processes would then occur from natural forces exerted on these weakened bony prominences via the common digital extensor tendon. Support for osteochondrosis as a cause of this bone cyst formation was seen in histologic examination of fragments removed. Within the bony trabeculae, a dysplastic focus of cartilage with mineralized plaques and osseous tissues was observed. Findings supported a diagnosis of osteochondrosis, to the extent that the disease is presently understood in horses. Surgical correction by fragment removal was performed to circumvent progression of degenerative joint disease, which was evident as partial cartilage erosion of the distal dorsal articular surface of the second phalanx and fracture fragments. Recovery from surgery was rapid, and several months after surgery, the horse was sound for pleasure riding.  相似文献   

Tuberculosis and chronic demyelinating encephalitis in a parrot     

G M Snyder 《Modern veterinary practice》1979,60(6):466-468

  相似文献