1,721,010 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
On effect of primed cellular microcapsules and pH neutralizing biomaterials to augment regeneration of the intervertebral disc
No full textOne of the most common topics of research worldwide for medical health care is low back pain (LBP). It is widely accepted that LBP is associated with degeneration of the intervertebral disc (IVD), the shock absorbent soft tissue between the vertebral bodies. Degenerative discs disease (DDD) is characterised by increased cell death and loss in structural extracellular matrix (ECM) molecules within the nucleus pulposus (NP) tissue, the highly hydrated gelatinous tissue in the centre of the IVD. Being an avascular structure, the nutrient supply within the IVD is limited, resulting in a compromised microenvironment with limited oxygen and glucose, and a low pH. These can drop even lower during the progression of disc degeneration resulting in further cell death and loss of structural integrity. Cell-based therapy has been proposed to re-establish the natural cell population within the disc and subsequentially re-produce matrix molecules for a healthy IVD. Some success has been made using NP cells, yet shortcomings for a long-term solution remain such as poor cell yield post-isolation, limited matrix forming capacities, and cell death and leakage during re-injections. The overall objective of this thesis was to develop an injectable biomaterial that successfully delivers cells into the disc while preserving their capability to sustain the harsh microenvironment characteristic of degenerative disc. Specifically, this thesis investigates i) technical challenges associated with intradiscal injections of cells (i.e. cell damage due to shear forces) by establishing a material for consistent delivery into the disc and ii) a strategy to overcome the microenvironmental limitations found in degenerated disc, with specific focus on the acidic pH. The thesis began by characterizing the electrohydrodynamic spraying (EHDS) technology for microencapsulation of cells into ionically crosslinked alginate hydrogels. Adjusting the operation settings, injectable microcapsules (μCaps) were successfully fabricated with entrapped cells in an optimised seeding density for matrix accumulation. These were further capable to sustain shear stress during injection through a needle. Thereafter, a viscous bulking agent was developed using a fibrin-hydrogel base to enhance μCap delivery into the highly pressurized IVD. A fibrin-hyaluronic acid (HA) blend was found to induce increased proliferation and matrix deposition of cells, making the advantages of the bulking agent two-fold: i) enhanced μCap delivery into the disc and ii) promoted disc-like tissue formation for better regeneration potential. The thesis continued by exploring a way to improve cellular response to the acidic environment of the IVD. Three different pH conditions (pH 7.1, 6.8 and 6.5), representative for different stages of disc degeneration, were investigated using articular chondrocytes (AC) and bone marrow-derived stem cells (BMSC) with and without priming using TGF-β3. By priming the cells, the detrimental pH effect observed on cells without priming was overcome with significantly improved viability and ECM levels for both cell types in all pH levels investigated. Finally, the challenging acidic microenvironment was altered using pH neutralizing antacids. After applying EHDS to fabricate antacid microcapsules, efficient pH increase was found using CaCO3 nanoparticles inside alginate μCaps with a slow release kinetics for long lasting neutralization effects. Exploring the established hybrid-hydrogel containing EHDS fabricated cellular μCaps (AC or BMSC) and CaCO3 μCaps within the fibrin-HA bulking gel, within a disc explant model, elevation of core pH was successfully established. Moreover, improved matrix retention within the disc tissue was accomplished with both cell types, AC and BMSC. To conclude, this thesis describes a novel approach to develop an injectable material for minimally invasive treatment of the degenerated IVD. A hybrid hydrogel was established containing i) μCaps with primed cells to deposit de novo matrix into the acidic microenvironment of the disc and aid resident cells to re-establish their potential by paracrine signalling, ii) μCaps containing CaCO3 nanoparticles to elevate local pH and subsequentially enhance cell viability and matrix accumulation of resident cells and iii) a fibrin-HA bulking agent to facilitate μCap deposition into the IVD while promoting cell proliferation and disc-like matrix accumulation
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Response of bovine 3D seeded nucleus pulposus cells on expansion conditions
No full textAutologous disc chondrocyte transplantation (ADCT) is the only currently available medical treatment which aims to regenerate diseased intervertebral discs. Reaching appropriate number of cells fast enough as well as retention of right phenotype are main limitations of ADCT. Objective of this study was to investigate effect of FGF-2 and TGF-?3 growth factors on nucleus pulposus (NP) cells in ADCT. We investigated the effect of expansion condition on bovine NP cells cultured in alginate beads. Expansion included four different conditions varying presence of oxygen and FGF-2. After NP cells were encapsulated in 1.5% alginate hydrogel beads, they were cultured in hypoxic conditions for 21 days with and without presence of TGF-?3, while portion of cells were initially encapsulated without expansion to act as control group. Additionally, expanded cells of the four groups were used to measure proliferation kinetics over a period of 7 days. Presence of FGF-2 increased the ability of cells to proliferate in 2D culture, showing significant difference between groups expanded in the presence or absence of FGF-2. Presence of TGF-?3 during cultivation in alginate beads induced significantly bigger proliferation in respect to the groups cultivated without TGF-?3. Fresh NP cells showed greater ability to produce sulphated glycosaminoglycans (sGAG) without TGF in respect to the other groups (23.47?1.29 vs 7.82?2.09 ?g/?g of DNA, against best group of expanded cells). Groups cultivated in presence of TGF-?3 showed significant increase in sGAG production in all cases. Results imply that FGF-2 can be beneficial in order to accelerate the expansion rate for ADCT treatments. Proliferation in 3D appears to be promoted by TGF-?3 in all conditions, as well as in the case of fresh cell group. Accumulation of sGAG in alginate beads is improved with addition of TGF-?3 which demonstrates importance of this growth factor on restoration of phenotype of cells in 3D condition.Autologous disc chondrocyte transplantation (ADCT) is the only currently available medical treatment which aims to regenerate diseased intervertebral discs. Reaching appropriate number of cells fast enough as well as retention of right phenotype are main limitations of ADCT. Objective of this study was to investigate effect of FGF-2 and TGF-?3 growth factors on nucleus pulposus (NP) cells in ADCT. We investigated the effect of expansion condition on bovine NP cells cultured in alginate beads. Expansion included four different conditions varying presence of oxygen and FGF-2. After NP cells were encapsulated in 1.5% alginate hydrogel beads, they were cultured in hypoxic conditions for 21 days with and without presence of TGF-?3, while portion of cells were initially encapsulated without expansion to act as control group. Additionally, expanded cells of the four groups were used to measure proliferation kinetics over a period of 7 days. Presence of FGF-2 increased the ability of cells to proliferate in 2D culture, showing significant difference between groups expanded in the presence or absence of FGF-2. Presence of TGF-?3 during cultivation in alginate beads induced significantly bigger proliferation in respect to the groups cultivated without TGF-?3. Fresh NP cells showed greater ability to produce sulphated glycosaminoglycans (sGAG) without TGF in respect to the other groups (23.47?1.29 vs 7.82?2.09 ?g/?g of DNA, against best group of expanded cells). Groups cultivated in presence of TGF-?3 showed significant increase in sGAG production in all cases. Results imply that FGF-2 can be beneficial in order to accelerate the expansion rate for ADCT treatments. Proliferation in 3D appears to be promoted by TGF-?3 in all conditions, as well as in the case of fresh cell group. Accumulation of sGAG in alginate beads is improved with addition of TGF-?3 which demonstrates importance of this growth factor on restoration of phenotype of cells in 3D condition
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
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