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排序方式: 共有259条查询结果,搜索用时 15 毫秒
41.
Infrared (IR) clear sky temperatures (Tsky), screen level temperature (T) and Precipitable Water Vapour (PWV) were collected for a period of 2 years from a coastal region of southern Australia. IR sky temperatures were derived from simple infrared detectors, which have been developed by the authors for inexpensive monitoring of cloud cover, while data for PWV were obtained from Global Positioning Satellite (GPS) transmissions. Meteorological data were obtained from the Australian Bureau of Meteorology. Based on these data, statistical regression analyses between nocturnal Tsky and the T and PWV (one variable fit) were conducted. Direct proportional relationships between Tsky and T and between Tsky and PWV were found. The one variable fit was further optimized by applying the multiple regression fit between Tsky and both T and PWV. The resulting multilinear model was essentially unbiased, with a correlation coefficient (R2) of 0.97, mean bias error (MBE) of ?2.7 × 10?5 °C, and root mean square error (RMSE) of about 1.6 °C. The performance of the multilinear model was tested against a 1-year independent data set. In this case, the predictability of the model was superior, with MBE and RMSE being 0.13 °C and 2.23 °C respectively. After correcting the daytime observations for the biases caused by solar heating of the detection system, the performance of this model in calculating the daytime measurements was tested and showed MBE and RMSE values of 1.3 °C and 2.5 °C, respectively. Additionally, twenty schemes from the literature were tested and assessed for predicting the measured sky temperature. The performances of these models were all different. Whereas most of them underestimated the measured sky temperatures, three of these models showed a reasonable prediction ability. Finally, the multilinear model was compared with the simulated sky temperatures obtained using MODTRAN software. Perfect agreements were found between the two temperatures. 相似文献
42.
A.N. Hristov M. Harper J. Oh F. Giallongo J.C. Lopes G. Cudoc J. Clay R. Ward L.E. Chase 《Journal of dairy science》2018,101(2):1579-1584
The main objective of this survey was to examine variability in milk urea nitrogen (MUN) for Dairy Herd Improvement Association (DHIA) herds in the northeastern United States (the Northeast), examine trends in dairy cow diet composition, and determine potential relationships for MUN and diet composition. Trends in milk fat and protein concentrations, milk yield, days in milk on test day, and lactation number of the cows were also evaluated. The data set for the survey included 10,839,461 DHIA dairy cow records from 2004 to 2015 for 13 states (CT, DE, MA, MD, ME, NH, NJ, NY, PA, RI, VA, VT, and WV) and was retrieved from Dairy Records Management Systems (Raleigh, NC). Average (across states and years) milk yield, milk fat, and milk protein were 31.6 ± 0.24 kg/d, 3.85 ± 0.021%, and 3.13 ± 0.013%, respectively. No obvious trends were observed for milk fat or protein content, but milk yield steadily increased during the survey period. Milk urea N concentration averaged 13.3 ± 0.13 mg/dL, with no obvious or consistent trends. Examination of variability in dairy feed cost and all milk price for the Northeast indicated that high MUN generally coincided with high feed cost and high milk price. For the diet composition survey, 9,707 records of total mixed ration (TMR) analyses, unrelated to the milk composition data set, from the Cumberland Valley Analytical Service (Maugansville, MD) database were examined. Concentration of TMR crude protein (CP) decreased from 17.1% in 2007 to 16.4% in 2015, but there was not an obvious trend in soluble protein concentration. Concentration of TMR neutral detergent fiber (NDF) and 24-h in vitro NDF degradability declined steadily during the survey period and was accompanied by a steady increase in TMR starch concentration. Examination of these unrelated data sets revealed lack of correlation between MUN and diet chemical composition. Thus, we conclude that individual cow MUN in Northeast dairy herds fluctuated between 2004 and 2015. It appeared that MUN followed variability in feed cost; however, ration feed ingredient data were not available to better define the reasons for the variations in MUN. 相似文献
43.
Kurt B. Waldman David L. Ortega Robert B. Richardson Daniel C. Clay Sieglinde Snapp 《Food Security》2016,8(6):1087-1099
Adoption rates of leguminous crops remain low in sub-Saharan Africa despite their potential role in improving nutrition, soil health, and food security. In this study we explored Malawian farmers’ perceptions of various legume attributes and assessed how these perceptions affected allocation of land to legume crops using a logit link model. We found high regional variation in both consumption- and production-related preferences, but relatively consistent preferences across samples. While scientific understanding and farmer perceptions were aligned on some topics and for some legumes, there were discrepancies elsewhere, particularly in terms of soil fertility and nutrition. Understanding why these discrepancies exist and where there were potential biases are critical in explaining the extent of adoption. In many cases perceptions of legume attributes may be influenced by the cultural role of the crop in the household, particularly in terms of food security or market-orientation. The findings also suggest that researchers need to look beyond both the agronomic properties and farmers’ preferences to fully understand the extent of adoption. Socioeconomic factors, biases, and marketing concerns may also influence integration of legumes into maize-based cropping systems. 相似文献
44.
Piva TJ Davern CM Hall PM Winterford CM Ellem KA 《International journal of molecular sciences》2012,13(3):2650-2675
We have previously shown that in HeLa cells treated with a variety of agents there is an increase in cell surface peptidase (CSP) activity in those cells undergoing apoptosis. The increase in CSP activity observed in UVB-irradiated cells undergoing apoptosis was unaffected when the cultures were treated with the aminopeptidase inhibitor bestatin, and matrix metalloprotease inhibitor BB3103, but greatly enhanced when treated with the caspase 3 inhibitor-DEVD, and reduced in the presence of the poly(ADP-ribose) polymerase (PARP) inhibitor-3-aminobenzamide (3AB). Neither 3AB nor DEVD had an effect on the gross morphology of the apoptotic cells observed under electron microscopy, nor did they have an effect on phosphatidylserine eversion on the cell membrane, or that of PARP cleavage. All the agents except for DEVD had no effect on the level of caspase 3 activity in the cells. The results suggest that other caspases may cleave PARP in these cells. Both 3AB and DEVD treatment reduced the level of actin cleavage seen in the apoptotic cells. The increase in CSP activity observed in cells undergoing UVB-induced apoptosis appears to involve PARP but not caspase 3. 相似文献
45.
Jaume S Knobe K Newton RR Schlimbach F Blower M Reid RC 《IEEE transactions on bio-medical engineering》2012,59(1):35-38
Several groups in neurobiology have embarked into deciphering the brain circuitry using large-scale imaging of a mouse brain and manual tracing of the connections between neurons. Creating a graph of the brain circuitry, also called a connectome, could have a huge impact on the understanding of neurodegenerative diseases such as Alzheimer's disease. Although considerably smaller than a human brain, a mouse brain already exhibits one billion connections and manually tracing the connectome of a mouse brain can only be achieved partially. This paper proposes to scale up the tracing by using automated image segmentation and a parallel computing approach designed for domain experts. We explain the design decisions behind our parallel approach and we present our results for the segmentation of the vasculature and the cell nuclei, which have been obtained without any manual intervention. 相似文献
46.
The objectives of this study were to estimate the heritability of body condition score loss (BCSL) in early lactation and estimate genetic and phenotypic correlations among BCSL, body condition score (BCS), production, and reproductive performance. Body condition scores at calving and postpartum, mature equivalents for milk, fat and protein yield, days to first service, and services per conception were obtained from Dairy Records Management Systems in Raleigh, NC. Body condition score loss was defined as BCS at calving minus postpartum BCS. Heritabilities and correlations were estimated with a series of bivariate animal models with average-information REML. Herd-year-season effects and age at calving were included in all models. The length of the prior calving interval was included for all second lactation traits, and all nonproduction traits were analyzed with and without mature equivalent milk as a covariable. Initial correlations between BCS and BCSL were obtained using BCSL and BCS observations from the same cows. Additional genetic correlation estimates were generated through relationships between a group of cows with BCSL observations and a separate group of cows with BCS observations. Heritability estimates for BCSL ranged from 0.01 to 0.07. Genetic correlation estimates between BCSL and BCS at calving ranged from -0.15 to -0.26 in first lactation and from -0.11 to -0.48 in second lactation. Genetic correlation estimates between BCSL and postpartum BCS ranged from -0.70 to -0.99 in first lactation and from -0.56 to -0.91 in second lactation. Phenotypic correlation estimates between BCSL and BCS at calving were near 0.54, whereas phenotypic correlation estimates between BCSL and postpartum BCS were near -0.65. Genetic correlations between BCSL and yield traits ranged from 0.17 to 0.50. Genetic correlations between BCSL and days to first service ranged from 0.29 to 0.68. Selection for yield appears to increase BCSL by lowering postpartum BCS. More loss in BCS was associated with an increase in days to first service. 相似文献
47.
Dechow CD Rogers GW Sander-Nielsen U Klei L Lawlor TJ Clay JS Freeman AE Abdel-Azim G Kuck A Schnell S 《Journal of dairy science》2004,87(10):3526-3533
The objectives of this study were to estimate genetic correlations among body condition scores (BCS) from various sources, dairy form, and measures of cow health. Body condition score and dairy form evaluated during routine type appraisal was obtained from the Holstein Association USA, Inc. A second set of BCS was obtained from Dairy Records Managements Systems (DRMS) and was recorded by producers that use PCDART dairy management software. Disease observations were obtained from recorded veterinarian treatments in several dairy herds in the United States. Estimated breeding values for diseases in Denmark were also obtained. Genetic correlations among BCS, dairy form, and cow health traits in the United States were generated with sire models. Models included fixed effects for age, DIM, and contemporary group. Random effects included sire, permanent environment, herd-year season for health traits, and error. Predicted transmitting abilities (PTA) for BCS and dairy form were correlated with estimated breeding values for disease in Denmark. The genetic correlation estimate between BCS from DRMS and BCS from the Holstein Association USA, Inc., was 0.85. The genetic correlation estimate between BCS and a composite of all diseases in the United States was -0.79, and PTA for BCS was favorably correlated with an index of resistance to disease other than mastitis in Denmark (0.27). Dairy form was positively correlated with a composite of all diseases in the United States (0.85) and was unfavorably correlated with an index for resistance to disease other than mastitis in Denmark (-0.29). Adjustment for protein yield PTA had a minimal affect on correlations between PTA for BCS or dairy form and disease in Denmark. Selection for higher body condition or lower dairy form with continued selection for yield may slow deterioration in cow health as a correlated response to selection for increased yield. 相似文献
48.
Clay WA Liu Z Yang W Fabbri JD Dahl JE Carlson RM Sun Y Schreiner PR Fokin AA Tkachenko BA Fokina NA Pianetta PA Melosh N Shen ZX 《Nano letters》2009,9(1):57-61
Recent photoemission experiments have discovered a highly monochromatized secondary electron peak emitted from diamondoid self-assembled monolayers on metal substrates. New experimental data and simulation results are presented to show that a combination of negative electron affinity and strong electron-phonon scattering is responsible for this behavior. The simulation results are generated using a simple Monte Carlo transport algorithm. The simulated spectra recreate the main spectral features of the measured ones. 相似文献
49.
50.
Thomas Parkinson Hui Zhang Ed Arens Yingdong He Richard de Dear John Elson Alex Parkinson Clay Maranville Andrew Wang 《Indoor air》2021,31(6):2266-2280
Research into human thermal perception indoors has focused on “neutrality” under steady-state conditions. Recent interest in thermal alliesthesia has highlighted the hedonic dimension of our thermal world that has been largely overlooked by science. Here, we show the activity of sensory neurons can predict thermal pleasure under dynamic exposures. A numerical model of cutaneous thermoreceptors was applied to skin temperature measurements from 12 human subjects. A random forest model trained on simulated thermoreceptor impulses could classify pleasure responses (F1 score of 67%) with low false positives/negatives (4%). Accuracy increased (83%) when excluding the few extreme (dis)pleasure responses. Validation on an independent dataset confirmed model reliability. This is the first empirical demonstration of the relationship between thermoreceptors and pleasure arising from thermal stimuli. Insights into the neurophysiology of thermal perception can enhance the experience of built environments through designs that promote sensory excitation instead of neutrality. 相似文献