828 research outputs found
Factorization of isometries of hyperbolic 4-space and a discreteness condition:
No full textGilman's NSDC condition is a sufficient condition for the discreteness of a two generator subgroup of PSL(2,C). We address the question of the extension of this condition to subgroups of isometries of hyperbolic 4-space. While making this new construction, namely the NSDS condition, we are led to ask whether every orientation preserving isometry of hyperbolic 4-space can be factored into the product of two half-turns. We use some techniques developed by Wilker to first, define a half-turn suitably in dimension 4 and then answer the former question. It turns out that defining a half-turn in this way in any dimension n enables us to generalize some of Gilman's theorems to dimension greater than or equal to 4. We also give an exposition on part of Wilker's work and give new proofs for some of his results.Ph.D.Includes bibliographical references (p. 52-53)by Karan Mohan Pur
Polyvinyl alcohol-poly(caprolactone) semi IPN scaffold with implication for cartilage tissue engineering
No full textPolycaprolactone is an FDA approved aliphatic polyester that is widely used as a scaffold for tissue engineering. It is hydrophobic and doesn't have any reactive functional groups on the polymer for further modification. Blending with other hydrophilic polymers like polyvinyl alcohol helps to generate a hybrid polymer with better properties. In this study we have been able to fabricate a novel porous 3D scaffold of Semi-IPN Poly (caprolactone)-Poly (vinyl alcohol). The Semi IPN is phase mixed and has synergistic properties of its constituent polymers. The hybrid scaffold is nontoxic and highly hydrophilic with greater percentage of swelling and is also amenable for further modification with bioactive peptides. Although porous with an open interconnected porous structure, the scaffold has adequate mechanical strength to withstand the load imparted by the cells during in vitro culture. Porcine chondrocytes seeded within the unmodified scaffolds secrete extra cellular matrix components revealing that the hybrid scaffold has immense potential for tissue engineering applications. (C) 2007 Wiley Periodicals, Inc
Bibliographics for the 983 eprints in the live archives of E-LIS : trends and status report up to 7th July 2004, based on author-self-archiving metadata
No full textThe priority for ideas and philosophy related to "Network Theory" have been traced back and documented by Braun(2004),and credit goes to Karinthy(1929).The IT has empowered to realise it, as the most practical phenomena and it is no more a humour. The OAI (Open Archives Initiatives)and ACIS (Academic Contributor Information System)are progressive in the direction ,which may lead to realise the "Collective Genius" at global level. Focus of present study is on Author-Self-Archiving (A-S-A)Metadata of the 983 Eprints in the Live Archives of the E-LIS (EPrints of Library and Information Science),which were approved till 7th July 2004.The A-S-A Metadata was used for librametric analysis. Self-explanatory bibliographics are illustrated.The highlights include: Conference papers (34%); highest approval, June 2004 (28%); published archives (76%);not refereed (52%); not in public domain (60%); highest self-archiving-author (De Robbio, Antonella).The Nos. of EPrints having single JITA domain specifications were: Theoretical and general aspects of libraries and information(27); Information use and sociology of information(80);Users,literacy and reading(13);Libraries as physical collections(30);Publishing and legal issues(57);Management(13);Industry, profession and education(36);Information sources, supports, channels(113) ; Information treatment for information services, Information functions and techniques (101); Technical services libraries, archives and museums(25); Housing technologies(1); Information technology and library technology(92); and Inter-domainery (395) i.e. having specifications of two or more than two JITA classes
A Synthetic Scaffold Favoring Chondrogenic Phenotype over a Natural Scaffold
No full textThe three-dimensional scaffolds play a very important role in regulating cell adhesion and the production of extracellular matrix molecules in in vitro regeneration of cartilage. This study evaluates how the three-dimensional structure and physicochemical properties of the polymeric scaffolds influence in vitro regeneration of cartilage tissue. A synthetic poly(vinyl alcohol)-poly(caprolactone) semi-interpenetrating polymer network (IPN) scaffold and gelatin-albumin, made of natural polymers, are used for the study. The polymers in the semi-IPN synthetic scaffold mimic the properties of collagen and glycosaminoglycans present in native cartilage. Its appropriate swelling and pore structure enabled cell-cell and cell-matrix interactions. This helped the chondrocytes to retain its spherical morphology and resulted in enhanced secretion of extracellular matrix components. In contrast, the biomimetic structure in gelatin-albumin scaffold induced chondrocytes to loose its phenotype by spreading and becoming fibroblastic in morphology. Its high swelling and the large pore size failed to recreate an appropriate microenvironment for chondrogenesis that resulted in less secretion of cartilage-specific molecules. Mesenchymal stem cell differentiation to chondrocytes in the presence of growth factors is also enhanced in the synthetic semi-IPN scaffold. The study thus indicates that the chemical composition and the physicochemical properties of the scaffolds play a very important role in providing appropriate niche in in vitro tissue regeneration
Designing a successful library school field experience
No full textTo share the library school field experience paradigm that the authors developed after their successful participation as a supervisor and student.
Design/methodology/approach – A review of field experience literature is provided. The field experience paradigms and perspectives pertaining to the supervisor and the student are explained. The paradigm is suggested as a model for field experience participants and their supervisors.
Findings – The field experience paradigm for the supervisors elucidates the stages – planning, training, mentoring and evaluation. The paradigm for students explains the phases – awareness, interests, planning and participation.
Research limitations/implications – The focus of the field experience, from which the paradigm emanated, was to train and prepare the student for agricultural librarianship in an academic library. The application of the paradigm may vary for different situations.
Practical implications – The paradigm is expected to be useful for supervisors and students of field experience programs.
Originality/value – This paradigm stems from the participation of the authors as a field experience supervisor and student. The steps and methods the authors followed will help advance future field experience programs
A 3D biodegradable protein based matrix for cartilage tissue engineering and stem cell differentiation to cartilage.
No full textA protein based 3D porous scaffold is fabricated by blending gelatin and albumin. The biomimetic biodegradable gelatin, promoted good cell adhesion and its hydrophilic nature enabled absorption of culture media. Albumin is proposed to serve as a nontoxic foaming agent and also helped to attain a hydrophobic-hydrophilic balance. The hydrophobic-hydrophilic balance and appropriate crosslinking of the scaffold avoided extensive swelling, as well as retained the stability of scaffold in culture medium for long period. The scaffold is found to be highly porous with open interconnected pores. The adequate swelling and mechanical property of the scaffold helped to withstand the loads imparted by the cells during in vitro culture. The scaffold served as a nontoxic material to monolayer of fibroblast cells and is found to be cell compatible. The suitability of scaffold for chondrocyte culture and stem cell differentiation to chondrocytes is further explored in this work. The scaffold provided appropriate environment for chondrocyte culture, resulting in deposition of cartilage specific matrix molecules that completely masked the pores of the porous scaffold. The scaffold promoted the proliferation and differentiation of mesenchymal stem cells to chondrocytes in presence of growth factors. The transforming growth factor, TGFbeta3 promoted better chondrogenic differentiation than its isoform TGFbeta1 in this scaffold
Growth factor-mediated effects on chondrogenic differentiation of mesenchymal stem cells in 3D semi-IPN poly(vinyl alcohol)-poly(caprolactone) scaffolds
No full textCells, signaling molecules and three-dimensional (3D) scaffolds are the major contributors to the in vitro regeneration of cartilage. This study evaluates the differentiation of mesenchymal stem cells to chondrocytes, in a 3D semi-interpenetrating polymer network (semi-IPN) scaffold that gives an appropriate niche for chondrogenic differentiation. The 3D semi-IPN scaffold poly(vinyl alcohol) and poly(caprolactone) mimics the properties of extracellular matrix of native cartilage. The chondrogenic differentiation of mesenchymal stem cells on the 3D scaffolds is carried out by supplementing signaling molecules like TGF beta 1, TGF beta 3, and BMP2 individually and in two different combinations. The results indicate that each growth factor supplement or combinations showed a different influence on cell morphology, overall distribution of cells, and secretion of cartilage specific molecules. We conclude from our results, that a combination of TGF beta 3 and BMP2 promotes better differentiation of mesenchymal stem cells to chondrocytes in our scaffold. This study hence points out that an appropriate combination of 3D scaffolds and signaling molecules are required in the differentiation and maintenance of the chondrogenic phenotype during in vitro regeneration of cartilage tissue. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res 94A: 146-159, 201
Rethinking web platform extensibility
No full textThe modern Web platform provides an extensible architecture that lets third party extensions, often untrusted, enhance and customize the Web browser and the Web applications. While the prevalence of extensions for both browsers and applications has been instrumental in making the Web browser hugely successful, there are two critical issues that the designers of the modern Web platform have not yet tackled in a principled manner. First, both the third party extensions and the extensible components of the Web platform include numerous vulnerabilities, which can compromise the security and privacy of end users. Second, the black-box and opaque nature of the Web platform limits the extent of extensibility achievable for Web developers, thereby hampering the development of novel browser-based user applications. This dissertation develops new tools and techniques to address the problem of insecure extensibility in the Web platform, proposes novel language and system level solutions to make extensibility a first class primitive for developing Web software, and demonstrates that these methods are applicable to real-world Web applications and Web browser extensions. Specifically, this dissertation makes the following three contributions. First, it studies and characterizes the problem of insecure JavaScript-based Web browser extensions using a specialized program analysis system, Sabre, which leverages JavaScript-level information flow mechanism to detect violations in client’s confidentiality and integrity arising from execution of untrusted extensions. Second, it formalizes the concept of transactions for JavaScript and implements Transcript, a language runtime system that allows hosting principals, i.e., Web browser and Web applications, to isolate untrusted JavaScript-based extensions using speculative execution. Lastly, this dissertation presents the design and implementation of Atlantis, a novel, extensible browser architecture that allows Web applications to define their own runtime environment and become more secure and robust. Atlantis enables developers with primitives to manage the Web application’s security and privacy, and removes their dependence on opaque, legacy Web interfaces.Ph. D.Includes bibliographical referencesby Mohan Dhawa
INSPEC database analysis for Knowledge Management records
No full textThe study deals with the Knowledge Management papers covered in the INSPEC, an international database on Information Science, Physical Sciences, Engineering and Computer Sciences. The papers have been analysed in terms of their content and other scientometric parameters
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