Eigenvalue localization for the tikhonova model of crystal growth     

Charlie H. Cooke  Philip W. Smith 《Journal of The Franklin Institute》1983,316(2):127-133

Matrix A with characteristic polynomial Q(z) is defined positive or negative Hurwitz according to whether Q(z) or Q(-z) is a Hurwitz polynomial. Leading principle sections of the Tikhonova growth matrix have associated characteristic polynomials P_n(-z) which satisfy the recursionThat the Tikhonova growth matrix is negative Hurwitz is established through applying the Wall-Stieltjes theory of continued fraction expansions to show the P_n(-z) are Hurwitz polynomials. The Kayeya-Enestrom theorem and a procedure for refinement of the Gerschgorin estimate are used to obtain analytical bounds on spectral radii for the Tikhonova model, which provides estimates of maximal growth rates. The theory allows generalization to more complicated growth models.  相似文献   

Mapping undergraduate chemistry students' epistemic ideas about models and modeling     

Katherine Lazenby  Avery Stricker  Alexandra Brandriet  Charlie A. Rupp  Kathryn Mauger-Sonnek  Nicole M. Becker 《科学教学研究杂志》2020,57(5):794-824

Developing and using scientific models is an important scientific practice for science students. Undergraduate chemistry curricula are often centered on established disciplinary models, and assessments typically provide students with opportunities to use these models to predict and explain chemical phenomena. However, traditional curricula generally provide few opportunities for students to consider the epistemic nature of models and the process of modeling. To gain a sense of how introductory chemistry students understand model changeability, model multiplicity, the evaluation of models, and the process of modeling, we use a construct-mapping approach to characterize the sophistication of students' epistemic knowledge of models and modeling. We present a set of four related construct maps that we developed based on the work of other scholars and empirically validated in an undergraduate introductory chemistry setting. We use the construct maps to identify themes in students' responses to an open-ended survey instrument, the models in chemistry survey, and discuss the implications for teaching.  相似文献   

The impact of gastrostomy feeding tubes on the early childhood education and care of young children     

Charlie Swan 《Support for Learning》2021,36(4):555-571

This article explores how gastrostomy feeding tubes can impact the early childhood education and care (ECEC) experiences of children. It presents findings from a small-scale study, which utilised the perspectives of early years educators and parents. The findings indicate that feeding tubes have both an opportunistic and restrictive impact within ECEC. Opportunity was evident through improved nutrition and health, which allowed familial respite and an increased attendance of ECEC. This enabled opportunities for social and explorative interactions. However, the complexities of having and supporting a feeding tube made accessing types of play and exploration challenging. Collaboration between the educators and parents was a crucial tool for success. Educators felt with experience and teamwork they could ensure the needs of children were met innovatively and safely. However, it was concluded clearer advice for attending ECEC settings with a feeding tube would benefit all involved and instil a sense of readiness.  相似文献   

Human adult stem cells from menstrual blood and endometrial tissue     

Julie Allickson  Charlie Xiang 《Journal of Zhejiang University. Science. B》2012,13(5):419-420

  相似文献   

Preserving the Past: An Early Interview Improves Delayed Event Memory in Children With Intellectual Disabilities          下载免费PDF全文

Deirdre A. Brown  Charlie N. Lewis  Michael E. Lamb 《Child development》2015,86(4):1031-1047

The influence of an early interview on children's (N = 194) later recall of an experienced event was examined in children with mild and moderate intellectual disabilities (CWID; 7–12 years) and typically developing (TD) children matched for chronological (7–12 years) or mental (4–9 years) age. Children previously interviewed were more informative, more accurate, and less suggestible. CWID (mild) recalled as much information as TD mental age matches, and were as accurate as TD chronological age matches. CWID (moderate) recalled less than TD mental age matches but were as accurate. Interviewers should elicit CWID's recall as early as possible and consider developmental level and severity of impairments when evaluating eyewitness testimony.  相似文献   

Competence is in the Eye of the Beholder: Perceptions of intellectually disabled child witnesses     

Deirdre A. Brown  Charlie N. Lewis 《International Journal of Disability, Development & Education》2013,60(1):3-17

This study examines mock jurors’ perceptions of a young witness according to whether or not he was described as having an intellectual disability. Our study examined perceptions of a child witness younger (five or seven years) than previously studied. Mock jurors (n = 71) viewed a short video excerpt of a boy recalling a personally experienced event, and then rated him across nine domains of eyewitness ability. The boy was described as either having an intellectual disability or typically developing. Participants rated the child more negatively on dimensions relating to cognitive competence, but not trustworthiness, when he was presented as having an intellectual disability. Participants also watched the child answer a series of suggestive questions; when described as having an intellectual disability he was rated as less accurate in responding to these. The findings have implications for the involvement of children with intellectual disabilities within the legal system.  相似文献   

Menstrual blood-derived mesenchymal stem cells differentiate into functional hepatocyte-like cells     

Xiao-zhou Mou  Jian Lin  Jin-yang Chen  Yi-fei Li  Xiao-xing Wu  Bing-yu Xiang  Cai-yun Li  Ju-ming Ma  Charlie Xiang 《Journal of Zhejiang University. Science. B》2013,14(11):961-972

Orthotopic liver transplantation (OLT) is the only proven effective treatment for both end-stage and metabolic liver diseases. Hepatocyte transplantation is a promising alternative for OLT, but the lack of available donor livers has hampered its clinical application. Hepatocyte-like cells (HLCs) differentiated from many multi-potential stem cells can help repair damaged liver tissue. Yet almost suitable cells currently identified for human use are difficult to harvest and involve invasive procedures. Recently, a novel mesenchymal stem cell derived from human menstrual blood (MenSC) has been discovered and obtained easily and repeatedly. In this study, we examined whether the MenSCs are able to differentiate into functional HLCs in vitro. After three weeks of incubation in hepatogenic differentiation medium containing hepatocyte growth factor (HGF), fibroblast growth factor-4 (FGF-4), and oncostain M (OSM), cuboidal HLCs were observed, and cells also expressed hepatocyte-specific marker genes including albumin (ALB), α-fetoprotein (AFP), cytokeratin 18/19 (CK18/19), and cytochrome P450 1A1/3A4 (CYP1A1/3A4). Differentiated cells further demonstrated in vitro mature hepatocyte functions such as urea synthesis, glycogen storage, and indocyanine green (ICG) uptake. After intrasplenic transplantation into mice with 2/3 partial hepatectomy, the MenSC-derived HLCs were detected in recipient livers and expressed human ALB protein. We also showed that MenSC-derived HLC transplantation could restore the serum ALB level and significantly suppressed transaminase activity of liver injury animals. In conclusion, MenSCs may serve as an ideal, easily accessible source of material for tissue engineering and cell therapy of liver tissues.  相似文献   

CHILDREN'S PLAYGROUND BEHAVIOUR ACROSS FIVE YEARS OF BROADCAST TELEVISION: A NATURALISTIC STUDY IN A REMOTE COMMUNITY     

Tony Charlton  Charlie Panting  Ronald Davie  David Coles  Lorraine Whitmarsh 《Emotional and Behavioural Difficulties》2013,18(4):4-12

3‐ to 8‐year‐olds’ free‐play behaviour was video‐recorded in two playgrounds before broadcast TV's availability in the South Atlantic island of St. Helena. Similar aged children's behaviour in the same playgrounds was recorded five years after television's arrival. Recorded behaviours were then coded for pro‐social and anti‐social acts. Out of sixty‐four pre‐lpost‐TV comparisons only nine significant shifts were found. Five revealed decreases in pro‐social behaviour (boys and girls), two showed increases in pro‐social behaviour (boys only), and the remaining two showed decreases in anti‐social behaviour (for boys only). In the discussion, particular environmental factors are highlighted which may help determine whether learned aggression (from TV and elsewhere) is enacted.  相似文献   

Academic Engagement in the Library Commons     

Charlie Bennett  Jon Bodnar 《Public Services Quarterly》2013,9(1):43-47

Abstract

Beginning in July 2002, the Health Sciences Library at the University of North Carolina at Chapel Hill underwent an 11 million dollar renovation. During three phases of the renovation, parts of the collection were inaccessible to patrons. In order to continue to make the library's collection available, library staff created a paging system. Patrons submitted requests for needed library materials using paper and electronic forms and library staff retrieved the requested items. The paging service was modified three times based on prior experience. Patrons were generally satisfied with the service. The renovation ended in December 2004.  相似文献   

“21世纪杯”全国中学生口语竞赛作品选     

Charlie 《英语辅导》2004,(9):45-47

“21世纪杯”第二届全国中学生英语口语竞赛于2003年12月在苏州成功举办。来自全国各地的各路英语高手参加了本次比赛。他们用流利的英语现场演讲和敏捷的答辩尽显了风采，也让在场的中外评委对  相似文献