The objective of this study was to determine the effect of temperature on whole milk density measured at four different temperatures: 5, 10, 15, and 20 °C. A total of ninety-three individual milk samples were collected from morning milking of thirty-two Holstein Friesian dairy cows, of national average genetic merit, once every two weeks over a period of 4 weeks and were assessed by Fourier transform infrared spectroscopy for milk composition analysis. Density of the milk was evaluated using two different analytical methods: a portable density meter DMA35 and a standard desktop model DMA4500M (Anton Paar GmbH, UK). Milk density was analysed with a linear mixed model with the fixed effects of sampling period, temperature and analysis method; triple interaction of sampling period x analysis method x temperature; and the random effect of cow to account for repeated measures. The effect of temperature on milk density (ρ) was also evaluated including temperature (t) as covariate with linear and quadratic effects within each analytic method. The regression equation describing the curvature and density–temperature relationship for the DMA35 instrument was ρ = 1.0338−0.00017T−0.0000122T2 (R2 = 0.64), while it was ρ = 1.0334 + 0.000057T−0.00001T2 (R2 = 0.61) for DMA4500 instrument. The mean density determined with DMA4500 at 5 °C was 1.0334 g cm−3, with corresponding figures of 1.0330, 1.0320 and 1.0305 g cm−3 at 10, 15 and 20 °C, respectively. The milk density values obtained in this study at specific temperatures will help to address any bias in weight–volume calculations and thus may also improve the financial and operational control for the dairy processors in Ireland and internationally. 相似文献
Contends, on the basis of posited social-role theory of gender and helping, that the male gender role fosters helping that is heroic and chivalrous, whereas the female gender role fosters helping that is nurturant and caring. In social psychological studies, helping behavior has mainly been examined in the context of short-term encounters with strangers. This focus has tended to exclude from the research literature those helping behaviors prescribed by the female gender role, because they are displayed primarily in long-term, close relationships. In contrast, the helping behaviors prescribed by the male gender role have been generously represented in research findings because they are displayed in relationships with strangers as well as in close relationships. Results from a meta-analytic review of sex differences in 172 studies (appended) in helping behavior indicate that in general men helped more than women and women received more help than men. Nevertheless, sex differences in helping were inconsistent across studies and were successfully predicted by various attributes of the studies and the helping behaviors. (96 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
The experiments reported are part of our effort to dissociate the tumor-enhancing effects of dietary fat and high caloric
intake. Rats either were fed ad libitum diets containing 4% corn oil or their calories were restricted by 40% and their diets
contained 13.1% corn oil. Incidence of 7,12-dimethylbenz(a)anthracene (DMBA)-induced mammary tumors was 80% in rats fed ad
libitum and 20% in those fed the calorie-restricted diets. Incidence of 1,2-dimethylhydrazine (DMH)-induced colon tumors was
100% in rats fed ad libitum and 53% in those whose caloric intake was restricted by 40%. The tumor yield (tumors per tumor-bearing
rat) was significantly lower in rats on caloric restriction. In another series, rats were fed diets containing 5, 15 or 20%
corn oil ad libitum or were fed calorie-restricted (by 25%) diets which provided 20 or 26.6% corn oil (therefore, the same
absolute amount of fat was consumed in each of the pair-fed groups). Tumor incidence and tumor yield in the two calorie-restricted
groups were similar to those seen in the rats fed 5% fat ad lititum; tumor burden (total g of tumor) was 45–65% lower in the
calorie-restricted rats. The data suggest that caloric intake is a more stringent determinant of tumor growth than fat intake. 相似文献
This paper addresses the problem of learning situation models for providing context-aware services. Context for modeling human behavior in a smart environment is represented by a situation model describing environment, users, and their activities. A framework for acquiring and evolving different layers of a situation model in a smart environment is proposed. Different learning methods are presented as part of this framework: role detection per entity, unsupervised extraction of situations from multimodal data, supervised learning of situation representations, and evolution of a predefined situation model with feedback. The situation model serves as frame and support for the different methods, permitting to stay in an intuitive declarative framework. The proposed methods have been integrated into a whole system for smart home environment. The implementation is detailed, and two evaluations are conducted in the smart home environment. The obtained results validate the proposed approach. 相似文献
Enantioselective catalytic epoxidation of olefins is an important problem from both practical and mechanistic points of view. The origins of chiral induction by asymmetric porphyrin and salen complexes were investigated by FT-NMR T1 relaxation techniques. A new chiral vaulted porphyrin (1) that carries (S)-binaphthyl-L-alanine straps across both faces of the porphyrin macrocycle was synthesized and characterized. (R)-styrene oxide was obtained in > 90% ee in the initial stages of styrene epoxidation with F5PhIO catalyzed by 1-Fe(III)Cl. The transition state for olefin epoxidation with high-valent metal-oxo species was modeled by coordinating epoxides to paramagnetic copper complexes of the corresponding ligands. The epoxide enantiomer that better fit the chiral cavity of the catalyst, as revealed by T1 relaxation measurements, was also the major product of catalytic olefin epoxidation. These results are consistent with the "lock-and-key" mechanism of asymmetric catalysis by metalloporphyrins. The copper complex of a chiral salen ligand showed no differentiation in terms of T1 relaxation rates between the enantiomers of cis-beta-methylstyrene oxide in contrast to the high enantioselectivity observed for catalytic epoxidation. 相似文献
OBJECTIVE: The study was done to determine whether thermal comfort (TC), thermal sensation (TS), and subjective factors gauging environmental stress were negatively affected with different cooling methods in men exercising in chemical protective clothing. BACKGROUND: Previous studies have reported that intermittent regional cooling improved the efficacy of cooling as compared with constant cooling (CC), but no studies have addressed whether there is any improvement in thermal comfort. METHODS: Eight male volunteers exercised at moderate work intensity (425 W) in three microclimate cooling tests. The circulating fluid in the cooling garment was provided during exercise to the head (6% body surface area [BSA]), torso (22% BSA), and thighs (44% BSA) and manipulated under three methods: (a) CC, (b) pulsed cooling (PC), and (c) PC activated by mean skin temperature (T(sk)) control (PC(skin)). TC and TS ratings were recorded every 20 min during the 80-min test. RESULTS: TC and TS ratings were not different for PC(skin) and CC; thus the participants perceived PC(skin) as being similar to CC. TS was significantly warmer with PC than with PC(skin) and CC (p < .001). In PC(skin), T(sk) was significantly higher than in PC and CC (p < .001), and PC(skin) was rated as being not as warm as PC according to TS. CONCLUSION: This indicates that the PC(skin) method was perceived as being as cool as CC and cooler than PC. APPLICATION: These findings indicate that the PC(skin) cooling method is an acceptable alternative to CC and PC based on human perceptions. 相似文献
This paper defines the difference of low-pass (DOLP) transform and describes a fast algorithm for its computation. The DOLP is a reversible transform which converts an image into a set of bandpass images. A DOLP transform is shown to require O(N2) multiplies and produce O(N log(N)) samples from an N sample image. When Gaussian low-pass filters are used, the result is a set of images which have been convolved with difference of Gaussian (DOG) filters from an exponential set of sizes. A fast computation technique based on ``resampling' is described and shown to reduce the DOLP transform complexity to O(N log(N)) multiplies and O(N) storage locations. A second technique, ``cascaded convolution with expansion,' is then defined and also shown to reduce the computational cost to O(N log(N)) multiplies. Combining these two techniques yields an algorithm for a DOLP transform that requires O(N) storage cells and requires O(N) multiplies. 相似文献
Short-term selective breeding created mouse lines divergent for ethanol drinking (high drinking short-term selected line [STDRHI], low drinking [STDRLO]) or ethanol-induced conditioned taste aversion (CTA; high [HTA], low [LTA]). Compared with STDRLO, STDRHI mice consumed more saccharin and less quinine, exhibited greater ethanol-induced conditioned place preference (CPP), and showed reduced ethanol stimulation and sensitization under some conditions; a line difference in ethanol-induced CTA was not consistently found. Compared with LTA, HTA mice consumed less ethanol but were similar in saccharin consumption, sensitivity to ethanol-induced CPP, and ethanol-induced locomotor stimulation and sensitization. These data suggest that ethanol drinking is genetically associated with several reward-and aversion-related traits. The interpretation of ethanol-induced CTA as more genetically distinct must be tempered by the inability to test the CTA lines beyond Selection Generation 2. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
This paper describes a new approach to mobile robot position estimation, based on principal component analysis of laser range data. An eigenspace is constructed from the principal components of a large number of range data sets. The structure of an environment, as seen by a range sensor, is represented as a family of surfaces in this space. Subsequent range data sets from the environment project as a point in this space. Associating this point to the family of surfaces gives a set of candidate positions and orientations (poses) for the sensor. These candidate poses correspond to positions and orientations in the environment which have similar range profiles. A Kalman filter can be used to select the most likely candidate pose based on coherence with small movements.
The first part of this paper describes how a relatively small number of depth profiles of an environment can be used to generate a complete eigenspace. This space is used to build a representation of the range scan profiles obtained from a regular grid of positions and orientations (poses). This representation has the form of a family of surface (a manifold). This representation converts the problem of associating a range profile to possible positions and orientations into a table lookup. As a side benefit, the method provides a simple means to detect obstacles in a range profile. The final section of the paper reviews the use of estimation theory to determine the correct pose hypothesis by tracking. 相似文献
This article reports on efforts to create an administrative structure for learning and teaching multimodal composing that depends not on the leadership of a new media writing expert but on the collaboration of relative novices organized according to principles of emergent learning. Based on four years’ experience in a grant-funded program that supports new media composing in multiple disciplines, I report on the benefits of a bottom-up, emergent approach while raising questions about the long-term sustainability of such an approach. I conclude by describing efforts to create more top-down support for new media composing, while remaining committed to serving the teachers and students who are the real agents of change. 相似文献