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61.
In this first investigation of genetic and environmental influences on children's values, 271 German twin pairs (50.2% boys) reported their values at ages 7–11 years using the Portrait Values Questionnaire (Schwartz & Rubel, 2005). We distinguished between gender-neutral (conservation vs. openness to change) and gender-typed (self-transcendence vs. self-enhancement) values. Boys differed from girls in the importance given to gender-typed benevolence, achievement, and power values. Gender-neutral values showed moderate (.34) and gender-typed values showed higher (.49) heritability, with nonshared environment and error accounting for the remaining variance. For both sexes, substantial genetic effects accounted for the importance children gave to their respective gender-stereotypical end of the self-transcendence versus self-enhancement dimension. However, dramatic sex differences emerged in the gender-atypical end of the distribution. For girls, low self-transcendence (high gender-atypical values) showed a large (.76) group heritability. For boys, gender-atypical values (high self-transcendence) showed no heritability and a modest (.10) shared environment effect. (PsycINFO Database Record (c) 2011 APA, all rights reserved) 相似文献
62.
63.
Tomasz Goofit Pawe Maksimowski Ariel Biernacki 《Propellants, Explosives, Pyrotechnics》2013,38(2):261-265
The synthesis of potassium dinitramide (KDN), an intermediate in the ammonium dinitramide (ADN) synthesis, was optimized to reduce the costs of the ADN synthesis in order to facilitate competitiveness of this oxidizer with ammonium perchlorate (AP). The optimal conditions for the synthesis of KDN like feedstock molar ratio, nitration time, and temperature were determined. KDN was obtained in ca. 48 % yield. The modifications introduced allowed to reduce feedstock consumption and energy intensity of the process. 相似文献
64.
In modern communication networks which offer multiple classes of services, an appropriate assignment of service classes to
users (or applications) will have a key influence on the performance profile. Differentiated pricing is an important tool
for guiding the user's choice. We consider a basic model for a multiclass system that offers multiclass services to multiple
types of traffic, and propose a pricing framework which is based on the concept of nominal traffic assignment. Users (or their
associated traffic) are categorized into a finite number of traffic types, which are distinct in their performance utilities
at the different service classes. The system administrator specifies a required traffic assignment, which associates with
each traffic type a nominal service class. Users, on the other hand, choose service classes so as to optimize their own performance.
Optimal prices should provide incentives for the users to assign each traffic type to its nominal service class. Our goal
is to implement a simple pricing scheme that provides such incentives. We establish necessary and sufficient conditions for
the existence of optimal prices and provide an algorithm for their computation. We indicate that optimal prices can tolerate
fluctuations in the various parameters. Next, we propose a distributed algorithm, which can be used by the system to compute
optimal prices even when it does not have sufficient knowledge of traffic characteristics. We then generalize our analysis
to an extended model, which explicitly includes congestion effects.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
65.
Maria Fernanda Garcs Julieth Daniela Buell-Acosta Edith ngel-Müller Arturo Jos Parada-Baos Jaidy Acosta-Alvarez Harold Felipe Saavedra-Lpez Roberto Franco-Vega Luis Miguel Maldonado-Acosta Franklin Escobar-Cordoba Keydy Vsquez-Romero Ezequiel Lacunza Sofía Alexandra Caminos-Cepeda Rubn Nogueiras Carlos Diguez Ariel Ivn Ruiz-Parra Jorge Eduardo Caminos 《International journal of molecular sciences》2022,23(17)
The Liver-Expressed Antimicrobial Peptide 2 (LEAP-2) has emerged as an endogenous GHS-R antagonist and blunts the orexigenic action of ghrelin. This study aimed to determine the Ghrelin/LEAP-2 ratio in humans and rats during pregnancy. In humans, we conducted a nested case-control study within an observational prospective cohort. Healthy and mild preeclamptic pregnant women were studied at each trimester of gestation and three months postpartum. In addition, a group of non-pregnant women was studied into the follicular and luteal phases of the menstrual cycle. Furthermore, Ghrelin/LEAP-2 ratio was investigated in non-pregnant rats and at different periods of rat pregnancy. Human and rat serum ghrelin and LEAP-2 levels were determined using the commercially available ELISA kits. The Ghrelin/LEAP-2 ratio peak around the second trimester of gestation in healthy pregnant women (p < 0.05). Additionally, there were no statistically significant differences in Ghrelin/LEAP-2 ratio between healthy and preeclamptic pregnant women at each trimester of gestation (p > 0.05). The Ghrelin/LEAP-2 ratio in pregnant rat reached the peak around mid-gestation with a similar pattern to the human pregnancy. LEAP-2 was visualized by immunohistochemistry in human term placenta and rat placentas on days 12, 16 and 21 of pregnancy. In conclusion, this study provides the first evidence of a Ghrelin/LEAP-2 ratio peak around the half-way point of pregnancy onwards during human and rat pregnancy, and it might be associated with increased rates of weight gain during pregnancy. Thus, this study suggests that LEAP-2 and Ghrelin/LEAP-2 ratio might play an important role in maternal physiology adaptation of weight gain during pregnancy. 相似文献
66.
Dr. Betul Kacar Dr. Amanda K. Garcia Dr. Ariel D. Anbar 《Chembiochem : a European journal of chemical biology》2021,22(1):114-119
Our understanding of life in the universe comes from one sample, life on Earth. Current and next-generation space missions will target exoplanets as well as planets and moons in our own solar system with the primary goal of detecting, interpreting and characterizing indications of possible biological activity. Thus, understanding life's fundamental characteristics is increasingly critical for detecting and interpreting potential biological signatures elsewhere in the universe. Astrobiologists have outlined the essential roles of carbon and water for life, but we have yet to decipher the rules governing the evolution of how living organisms use bioessential elements. Does the suite of life's essential chemical elements on Earth constitute only one possible evolutionary outcome? Are some elements so essential for biological functions that evolution will select for them despite low availability? How would this play out on other worlds that have different relative element abundances? When we look for life in the universe, or the conditions that could give rise to life, we must learn how to recognize it in extremely different chemical and environmental conditions from those on Earth. We argue that by exposing self-organizing biotic chemistries to different combinations of abiotic materials, and by mapping the evolutionary history of metalloenzyme biochemistry onto geological availabilities of metals, alternative element choices that are very different from life's present-day molecular structure might result. A greater understanding of the paleomolecular evolutionary history of life on Earth will create a predictive capacity for detecting and assessing life's existence on worlds where alternate evolutionary paths might have been taken. 相似文献
67.
Kleinerman Akiva Rosenfeld Ariel Ricci Francesco Kraus Sarit 《User Modeling and User-Adapted Interaction》2021,31(3):541-589
User Modeling and User-Adapted Interaction - Online platforms which assist users in finding a suitable match, such as online-dating and job recruiting environments, have become increasingly popular... 相似文献
68.
Catalyst design is key to the improvement of chemical process efficiency. The required work for the development of new catalysts can be supported through the proper application of artificial intelligence to identify optimal compositions. A generic methodology for the application of machine learning to catalysis research is therefore outlined in this work. The catalytic oxidation of SO2 was used to exemplify the first iteration of this methodology. 1784 data points from 31 published papers were compiled into a databank. The inlet SO2 concentration ranged from 0 to 66 mol%. An artificial neural network (ANN) was trained on the databank in order to predict SO2 conversion based on the catalyst composition and the reactor operating conditions (temperature, pressure, catalyst mass: volumetric flowrate ratio (w/v), and feed composition). The model achieved a root-mean-square error of 6.6%. A preliminary screening step identified 3:1 V-Mg/SiO2 catalysts as exhibiting high conversion at 648 K. A multi-objective optimization was then performed on a single catalyst to identify solutions exhibiting high conversion and high productivity at 648 K while minimizing the catalyst cost. The optimal solution was predicted to be a 2.9 wt% V/0.2 wt% Mg/SiO2 catalyst operating at a w/v of 7.49 kg-cat · s/m3 STP, achieving 100% SO2 conversion with a material cost among the bottom third of cost values. Artificial intelligence can then be employed to extract useful knowledge from published catalytic data and orient future search for novel catalyst development. 相似文献
69.
Incompatibility of the physical properties of concrete constituents — the aggregate and the cement paste — gives rise to microcracking when the material is cooled to very low temperatures. The phenomenon is complex and affected by a large number of factors. An analytical model of the cracking process could be instrumental in identifying parameters for experimental investigation. A preliminary study is presented, which models concrete as a two-phase medium consisting of the coarse aggregate as inclusions in the mortar matrix. A simplified finite element procedure is employed to evaluate the effects of four parameters on crack initiating temperature and on crack volume. The parameters include two physical properties — thermal expansion coefficient and elastic modulus — and two mix factors — inclusion/matrix volume fraction and inclusion particle size. Thermal coefficient and inclusion volume fraction emerge as the major parameters affecting the fracture process, but the relationship of the two mix factors is complex. 相似文献
70.
Many professionals play a role in evaluating and defining health service coverage in the current marketplace. It is useful to professional psychologists to understand how their perceptions of the current coverage of mental health services are similar to or different from those of other professionals. The authors examined the views of health insurance agents. Both psychologists and insurance agents agreed that, mental health benefits were adequate to effectively treat mild mental health problems, coverage was inadequate to treat major mental illness. Psychologists and insurance agents differed in their perceptions of whether patients and therapists used benefits unnecessarily. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献