Award Winner in the Young Investigator Category, 2014 Society for Biomaterials Annual Meeting and Exposition, Denver, Colorado, April 16-19, 2014: Periodically perforated core-shell collagen biomaterials balance cell infiltration, bioactivity, and mechanical properties.

Orthopedic tissue engineering requires biomaterials with robust mechanics as well as adequate porosity and permeability to support cell motility, proliferation, and new extracellular matrix (ECM) synthesis. While collagen-glycosaminoglycan (CG) scaffolds have been developed for a range of tissue engineering applications, they exhibit poor mechanical properties. Building on previous work in our lab that described composite CG biomaterials containing a porous scaffold core and nonporous CG membrane shell inspired by mechanically efficient core-shell composites in nature, this study explores an approach to improve cellular infiltration and metabolic health within these core-shell composites. We use indentation analyses to demonstrate that CG membranes, while less permeable than porous CG scaffolds, show similar permeability to dense materials such as small intestine submucosa (SIS). We also describe a simple method to fabricate CG membranes with organized arrays of microscale perforations. We demonstrate that perforated membranes support improved tenocyte migration into CG scaffolds, and that migration is enhanced by platelet-derived growth factor BB-mediated chemotaxis. CG core-shell composites fabricated with perforated membranes display scaffold-membrane integration with significantly improved tensile properties compared to scaffolds without membrane shells. Finally, we show that perforated membrane-scaffold composites support sustained tenocyte metabolic activity as well as improved cell infiltration and reduced expression of hypoxia-inducible factor 1α compared to composites with nonperforated membranes. These results will guide the design of improved biomaterials for tendon repair that are mechanically competent while also supporting infiltration of exogenous cells and other extrinsic mediators of wound healing.

从1995年国际景观生态学大会看当前国内外景观生态学发展的现状

对１９９５年世界景观生态学大会和景观生态学发展的国内外现状进行了思考。当今景观生态学与国际生态学的研究热点（全球变化、生物多样性和持续发展）基本一致，但又有自己的特色，其重点领域包括：①生态空间理论与景观异质性研究；②景观变化模型与未来景观规划；③景观系统分析与ＧＩＳ应用等。由于经济发展和社会生态意识的不同，使得该学科在各地区间的发展很不平衡。着重就我国的本领域研究状况与国际水平作了比较

我国主要类型生态系统结构功能与提高生产力途径研究──KJ85－06项目1991～1995研究进展简介

ＫＪ８５－０６项目是“八五”期间由中国科学院资助的最大的生态学研究计划．１９个研究所、２０个试验站、５３０余名科技人员参加了该项计划，５年总经费１０００万元．研究工作取得了重大进展，迄今已发表论文４５０余篇、专著３部，尚有大量论文与多部专著将陆续出版．本文简要介绍了有关主要研究进展，并就生态系统优化管理研究和生态过程、人类活动影响联网研究提出了两点主张．

Uncertainties in estimates of cropland area in China: a comparison between an AVHRR-derived dataset and a Landsat TM-derived dataset

The large uncertainties in estimates of cropland area in China may have significant implications for major cross-cutting themes of global environmental change-food production and trade, water resources, and the carbon and nitrogen cycles. Many earlier studies have indicated significant under-reporting of cropland area in China from official agricultural census statistics datasets. Space-borne remote sensing analyses provide an alternative and independent approach for estimating cropland area in China. In this study, we report estimates of cropland area from the National Land Cover Dataset (NLCD-96) at the 1:100,000 scale, which was generated by a multi-year National Land Cover Project in China through visual interpretation and digitization of Landsat TM images acquired mostly in 1995 and 1996. We compared the NLCD-96 dataset to another land cover dataset at I-km spatial resolution (the IGBP DIScover dataset version 2.0), which was generated from monthly Advanced Very High Resolution Radiometer (AVHRR)-derived Normalized Difference Vegetation Index (NDVI) from April, 1992 to March, 1993. The data comparison highlighted the limitation and uncertainty of cropland area estimates from the DIScover dataset. (C) 2003 Elsevier Science B.V. All rights reserved.

Study on spatial pattern of land-use change in China during 1995-2000

It is more and more acknowledged that land-use/cover dynamic change has become a key subject urgently to be dealt with in the study of global environmental change. Supported by the Landsat TM digital images, spatial patterns and temporal variation of land-use change during 1995 -2000 are studied in the paper. According to the land-use dynamic degree model, supported by the 1km GRID data of land-use change and the comprehensive characters of physical, economic and social features, a dynamic regionalization of land-use change is designed to disclose the spatial pattern of land-use change processes. Generally speaking, in the traditional agricultural zones, e.g., Huang-Huai-Hai Plains, Yangtze River Delta and Sichuan Basin, the built-up and residential areas occupy a great proportion of arable land, and in the interlock area of farming and pasturing of northern China and the oases agricultural zones, the reclamation I of arable land is conspicuously driven by changes of production conditions, economic benefits and climatic conditions. The implementation of "returning arable land into woodland or grassland" policies has won initial success in some areas, but it is too early to say that the trend of deforestation has been effectively reversed across China. In this paper, the division of dynamic regionalization of land-use change is designed, for the sake of revealing the temporal and spatial features of land-use change and laying the foundation for the study of regional scale land-use changes. Moreover, an integrated study, including studies of spatial pattern and temporal process of land-use change, is carried out in this paper, which is an interesting try on the comparative studies of spatial pattern on change process and the change process of spatial pattern of land-use change.

20 anos de experimentação em Integração Lavoura-Pecuária na Embrapa Agropecuária Oeste: relatório 1995-2015.

2015

Efectos de cambios impositivos en un modelo de equilibrio general aplicado: un análisis de la reforma de 1995

En este trabajo se analizan los efectos de una disminución de los tipos de las cotizaciones sociales, compensada con un incremento en los tipos del impuesto sobre el valor añadido, como la que tuvo lugar en España en 1995. Para ello se utiliza un modelo de equilibrio general aplicado a la economía española, que se presenta en dos versiones: una donde los sectores productivos se modelizan en competencia perfecta, y otra donde los mismos sectores se modelizan como oligopolistas a la Cournot, lo cual nos permite analizar la influencia del supuesto de competencia imperfecta sobre los resultados. Se ha realizado asimismo una simulación adicional aplicando un supuesto de equal yield por el que el déficit público y el nivel de bienestar del sector público se mantienen constantes tras la aplicación de la nueva política, con objeto de aislar los efectos secundarios que se podrían derivar de un cambio en el comportamiento del sector público.

Cestería en esparto Cerinza - Boyacá 1989-1995.

76 hojas : ilustraciones.

Canada's missionary congress; addresses delivered at the Canadian National Missionary Congress, held in Toronto, March 31 to April 4, 1909, with reports of committees.

http://www.archive.org/details/canadasmission00unknuoft/

Letter to D. A. Whedon. Pittsfield, April 30, 1845.

1845 handwritten letter from Daniel Denison Whedon to Daniel A. Whedon.

Letter to Daniel A. Whedon. New York. April 13, 1867

Handwritten 1867 letter from Daniel D. Whedon to his nephew, Daniel A. Whedon, requesting books.

Characteristics of WWW Client-based Traces

The explosion of WWW traffic necessitates an accurate picture of WWW use, and in particular requires a good understanding of client requests for WWW documents. To address this need, we have collected traces of actual executions of NCSA Mosaic, reflecting over half a million user requests for WWW documents. In this paper we describe the methods we used to collect our traces, and the formats of the collected data. Next, we present a descriptive statistical summary of the traces we collected, which identifies a number of trends and reference patterns in WWW use. In particular, we show that many characteristics of WWW use can be modelled using power-law distributions, including the distribution of document sizes, the popularity of documents as a function of size, the distribution of user requests for documents, and the number of references to documents as a function of their overall rank in popularity (Zipf's law). Finally, we show how the power-law distributions derived from our traces can be used to guide system designers interested in caching WWW documents.