超高含水原油混合流动及初始沉积特性     

邢晓凯  吕朝旭  刘珈铨 《中国科学院大学学报》2020,37(2):228-233

使用自行设计的实验装置,对超高含水原油的流动特性和初始沉积过程进行探究。系统研究实验温度、混合流速和体积含水率对超高含水原油初始沉积过程的影响,分析不同温度下原油的运动形态和初始沉积方式。初始沉积过程可分为蔓延沉积过程和粘连沉积过程,根据沉积特点和压降曲线的变化趋势将初始沉积过程分为3个阶段：沉积诱导期、快速沉积期和沉积动态平衡期。通过对沉积物碳数分布的分析,得知超高含水原油初始沉积过程中,同时存在剪切剥离作用、胶凝作用和分子扩散作用。实验温度和体积含水率主要通过改变胶凝作用和分子扩散来影响初始沉积过程,混合流速通过改变剪切剥离强度来影响初始沉积过程。  相似文献   

Impact of age on host responses to diet-induced obesity:Development of joint damage and metabolic set points     

Kelsey H.Collins  Graham Z.MacDonald  David A.Hart  Ruth A.Seerattan  Jaqueline L.Rios  Raylene A.Reimer  Walter Herzog 《运动与健康科学(英文)》2020,9(2):132-139,197

Background:Osteoarthritis is one of the leading causes of pain and disability worldwide,and a large percentage of patients with osteoarthritis are individuals who are also obese.In recent years,a series of animal models have demonstrated that obesity-inducing diets can result in synovial joint damage(both with and without the superimposition of trauma),which may be related to changes in percentage of body fat and a series of low-level systemic inflammatory mediators.Of note,there is a disparity between whether the dietary challenges commence at weaning,representing a weanling onset,or at skeletal maturity,representing an adult onset of obesity.We wished to evaluate the effect ofthe dietary exposure time and the age at which animals are exposed to a high-fat and high-sucrose(HFS) diet to determine whether these factors may result in disparate outcomes,as there is evidence suggesting that these factors result in differential metabolic disturbances.Based on dietary exposure time,we hypothesized that rats fed an HFS diet for 14 weeks from weaning(HFS Weanling) would demonstrate an increase in knee joint damage scores,whereas rats exposed to the HFS diet for 4 weeks,starting at 12 weeks of age(HFS Adult) and rats exposed to a standard chow diet(Chow)would not display an increase in knee joint damage scores.Methods:Male Sprague-Dawley rats were fed either an HFS diet for 14 weeks from weaning(HFS Weanling) or an HFS diet for 4 weeks,starting at 12 weeks of age(HFS Adult).At sacrifice,joints were scored using the modified Mankin Criteria,and serum was analyzed for a defined subset of inflammatory markers(Interleukin-6,leptin,monocyte chemoattractant protein-1,and tumor necrosis factorα).Results:When the HFS Weanling and HFS Adult groups were compared,both groups had a similar percent of body fat,although the HFS Weanling group had a significantly greater body mass than the HFS Adult group.The HFS Weanling and HFS Adult animals had a significant increase in body mass and percentage of body fat when compared to the Chow group.Although knee joint damage scores were low in all 3 groups,we found,contrary to our hypothesis,that the HFS Adult group had statistically significant greater knee joint damage scores than the Chow and HFS Weanling groups.Furthermore,we observed that the HFS Weanling group did not have significant differences in knee joint damage scores relative to the Chow group.Conclusion:These findings indicate that the HFS Weanling animals were better able to cope with the dietary challenge of an HFS diet than the HFS Adult group.Interestingly,when assessing various serum proinflammatory markers,no significant differences were detected between the HTS Adult and HFS Weanling groups.Although details regarding the mechanisms underlying an increase in knee joint damage scores in the HFS Adult group remain to be elucidated,these findings indicate that dietary exposure time maybe less important than the age at which an HFS diet is introduced.Moreover,increases in serum proinflammatory mediators do not appear to be directly linked to knee joint damage scores in the HFS Weanling group animals but may be partially responsible for the observed knee joint damage in the adults over the very short time of exposure to the HFS diet.  相似文献   

改进β约束的组合投资决策优化模型     

龙朝阳  王键  祝建军 《预测》2001,20(1):68-70

本文在研究了组合证券的系统风险与投资收益的内在联系的基础上，针对马柯维茨模型，使模型更具实用性。  相似文献   

紫苏子提取物的生理功能及其在水产养殖中的应用研究进展   总被引：4，自引：0，他引：4  

吕耀平 《丽水学院学报》2006,28(5):48-53

通过对紫苏子提取物的主要成分及生理功能描述,结合国内外该物质在生物中的应用现状,提出其在水产养殖中应注意的一些问题及重要的现实意义。  相似文献   

DNA microarray wet lab simulation brings genomics into the high school curriculum     

Campbell AM  Zanta CA  Heyer LJ  Kittinger B  Gabric KM  Adler L  Schulz B 《CBE life sciences education》2006,5(4):332-339

We have developed a wet lab DNA microarray simulation as part of a complete DNA microarray module for high school students. The wet lab simulation has been field tested with high school students in Illinois and Maryland as well as in workshops with high school teachers from across the nation. Instead of using DNA, our simulation is based on pH indicators, which offer many ideal teaching characteristics. The simulation requires no specialized equipment, is very inexpensive, is very reliable, and takes very little preparation time. Student and teacher assessment data indicate the simulation is popular with both groups, and students show significant learning gains. We include many resources with this publication, including all prelab introductory materials (e.g., a paper microarray activity), the student handouts, teachers notes, and pre- and postassessment tools. We did not test the simulation on other student populations, but based on teacher feedback, the simulation also may fit well in community college and in introductory and nonmajors' college biology curricula.  相似文献   

Simplified method of designing FIR filter with controllable center frequency     

黄翔东  褚晶辉  吕卫  崔海涛  王兆华 《天津大学学报(英文版)》2010,16(4):262-266

A novel simplified method is presented to design FIR filter with controllable center frequency. The properties of transfer curves for all-phase filters are illustrated under 3 windowing conditions. By combining single-window all-phase filter design steps and double phase-shift combination, a series of design formulas for point-pass filter, notch filter, band-pass filter and band-stop filter are derived, thus the design computation complexity is greatly reduced. Experiments prove that the center frequency of all the filters can be accurately specified at arbitrary position by adjusting frequency parameters m and λ.  相似文献   

Youth on the street: Abuse and neglect in the eighties   总被引：2，自引：0，他引：2  

Kathleen Kufeldt M.S.W.  PH.D.  Margaret Nimmo B.A.  B.P.E. 《Child abuse & neglect》1987,11(4):531-543

This paper discusses the findings of a study of runaways and homeless youth who were interviewed on the street the last week of every month on five week nights from late afternoon until 2 a.m. over a period of one year. The data derived from 489 interviews provided some interesting insights. Two distinct groups emerged from the analysis, generating a tentative hypothesis that the true "runners" tend to leave their homes with the intention of not returning and thus their runs are extended; the second group, designated "in and outers," use the run as a temporary coping mechanism. Their runs tend to be impulsive and of short duration. The study found that runaways (in particular the runners) are at great risk of being drawn into illegal activities. Major factors affecting this risk are distance from home and length of time on the run. A significant proportion of the youth interviewed had run from substitute care arrangements, and a disturbing implication emerging from the research is that adolescents in our society suffer from systemic abuse and neglect. One outcome of this piece of research was the opening of a safe house for early runners in January 1987. The operation of the house includes careful compilation of data to further advance understanding of the runaway population and its needs.  相似文献   

Educational program on evaluation of alleged sexual abuse victims     

Roberta A. Hibbard M.D.  Janet Serwint M.D.  Monica Connolly M.S.W. 《Child abuse & neglect》1987,11(4):513-519

Increased awareness of the problem of child sexual abuse has resulted in increasing numbers of children presenting to professionals for the evaluation of possible sexual victimization. A multidisciplinary project to develop professionals' knowledge and skills in the identification and evaluation of possible victims is described. The program focused on the child as a victim and emphasized developmental perspectives with regard to identification, interviewing children, the medical examination, and children in the legal system. Fifty-one medical and social work professionals from ten Indiana counties attended the program and responded to questionnaires about their experience and knowledge. Of 40 (78%) respondents, 63% had had no previous training in the medical evaluation for child sexual abuse. Child protective workers referred alleged victims primarily to the child's regular physician (37%) or emergency room (31%) for medical examination. Knowledge about child sexual abuse improved significantly at two weeks postsymposium (p = .001) and remained improved at six months postsymposium (p less than .02). These original participants have subsequently organized similar multidisciplinary programs in their local communities for medical, social, law enforcement, and legal professionals; thus, they have been "seeds" for further educational and cooperative efforts throughout the state.  相似文献   

Eardrum perforation as evidence of child abuse   总被引：2，自引：0，他引：2  

M N Obiako 《Child abuse & neglect》1987,11(1):149-151

  相似文献   

Mental health care for foster children in California   总被引：3，自引：0，他引：3  

L Klee  N Halfon 《Child abuse & neglect》1987,11(1):63-74

This paper reports on a study conducted to assess the health care needs of foster children in California. To evaluate foster children's mental health problems and the services provided to meet them, 154 program administrators, social workers, foster parents, and health care providers were interviewed in 14 counties. Foster parents and social workers were interviewed in groups, and foster parents and administrators also completed questionnaires. We found that although all counties care immediately for children who are injured, abused, or ill, only one county performs routine mental health evaluations of all children, and in most counties less than a third of children ever receive such evaluations. Informants identified mental health problems as more severe than medical problems in this population, and they identified four major barriers to access to appropriate therapy. Recommendations are that all children should receive comprehensive mental health evaluations, and procedures for immediate and ongoing care with consistent providers who are sensitive to foster children's needs should be included in case management plans, and covered by improved payment mechanisms. Additionally, communication, coordination and joint planning should be instituted among relevant agencies to address foster children's needs, and increased resources and training should be directed towards social service agencies and foster parents.  相似文献