1,720,974 research outputs found
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Variations on the Author
Get PDF“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
Get PDFWe 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
The role of AQP9 in mannitol-resistant oedema
No full textThe aquaglyceroporin, AQP9, facilitates the transport of water and other small neutral solutes through the cell membrane. It is expressed widely in the liver, while mRNA and/or protein expression has also been reported in lung, testis and brain tissue. The extent to which AQP9 is expressed in the human brain remains unclear. In rodents, it was shown that the expression of AQP9 is upregulated under hypoxia and/or hyperosmolality induced by mannitol. Mannitol is a sugar alcohol that is used medically as a hyperosmotic medication in the treatment of patients with cerebral oedema post-stroke or traumatic-brain injury (TBI). Mannitol exerts its effect by increasing blood osmolarity, causing accumulated fluid in swollen brain tissue to move into the blood stream for excretion by the kidneys. However, resistance to mannitol therapy has been documented after multiple doses of mannitol. The hypothesis tested in this thesis is that hypoxia and/or hyperosmolarity induced by mannitol increase AQP9 mRNA and protein expression. This enables mannitol to enter swollen astrocyte brain cells through the AQP9 channel, thereby ablating the osmotic gradient. AQP9 mRNA and protein expression were investigated in human astrocytes through qPCR and western blot, respectively. The mannitol permeability of these cells was probed using a calcein quenching permeability assay following hypoxia and/or mannitol treatment with/without known AQP9 inhibitors. AQP9 mRNA and protein expression were both upregulated in a time dependent manner following 1% hypoxic incubation for 24-72 h, although the magnitude of the response was subject to inter-donor variation between the astrocytes being assayed. Astrocytes incubated under hypoxia for 24-72 h with/without 5% mannitol showed a time-dependent elevation in their mannitol permeability which was reversed by two established AQP9 inhibitors, phloretin and RG100204. A novel AQP9 inhibitor, EATA-2A, produced by Dr Zaid Alobaidi at Aston University was also characterised. Protein kinase A and/or calmodulin may play a role in AQP9 expression and/or surface localisation. Overall, the work in this thesis shows that AQP9 is expressed in the human brain following hypoxia and/or mannitol treatment and that AQP9 is a mannitol channel. These findings would explain the resistance to mannitol therapy observed in patients suffering cerebral oedema; in vivo experiments are now required to validate this hypothesis
The progression of epileptogenesis in cultured juvenile rodent slices
Get PDFThe investigation of the brain’s physiological activity is subject to a range of compromises; the fidelity and spatial resolution of data from cells and networks must be balanced with maintaining as natural an environment and as much connectivity as possible. This is further complicated when measuring aberrant cellular and network activity in models of neurological conditions such as epilepsy or performing longitudinal studies looking at drug treatment or the development of recurrent seizure- like events. This thesis will present the deployment and optimisation of an organotypic slice culture preparation, using both rodent tissue and slices created from tissue blocks taken from human paediatric epilepsy patients experiencing refractory seizures. The naïve rodent tissue can be maintained relatively easily in a physiological state or provoked into exhibiting spontaneous recurrent seizure-like events which are responsive to a variety of pharmacological treatments both acutely and over days/weeks of treatment. This approach in rodent slice cultures allows for experimental manipulation of brain tissue rapidly, repeatably and over a longer time-period than an acute slice preparation would allow as slices were viable for testing for up to 2 weeks post extraction. However, human tissue slices were more difficult to obtain and to maintain in culture, making them significantly more difficult to obtain results of pharmacological activity from. The process of optimisation, including the assessment of various culture mediums, different ages of animal, antibiotic testing, and experimenting with new materials for culture substrates, is discussed and the preparation tested with a range of common anti-epileptic drugs, as well as the development of epileptiform activity being followed via cellular and network-level in vitro electrophysiology. The novel antiepileptic drugs that will be tested the tricyclic antidepressant tianeptine and the anorectic dexfenfluramine, as they have both shown potential to be. These drugs were tested both acutely and at a low concentration applied chronically to the organotypic cultures. The results obtained from these studies illustrate the advantage of the culture approach with longitudinal dosing showing promising results in our hands. The finding in this thesis suggest that dexfenfluramine shows promise as a therapeutic treatment for epilepsy, results obtained when testing tianeptine were much more variable, but they do indicate that at administered chronically at low doses tianeptine suppresses seizure activity
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
Dynamical Changes in Neuronal Network Function Underlying Epileptogenesis in the Temporal Lobe
Get PDFEpilepsy is a common neurological disorder characterized by recurrent seizures. Even before the presentation of the first seizure, it is believed there is a chronic pathogenic process underlying the network, cellular and synaptic changes which result in the development of symptomatic epilepsy – termed epileptogenesis. Epileptogenesis involves several crucial, progressive steps which develop over a period of weeks, months or sometimes years: the initial precipitating assault/injury, the latent period, and spontaneous recurrent seizures (SRS). Understanding the development and progression of epileptogenesis within the temporal lobe offers a new avenue for controlling or even preventing the development of symptomatic epilepsy. Animal models of epilepsy allow researchers to investigate the pathogenic process’ of epilepsy and explore possible therapeutics, including anti-epileptic drugs. A low mortality, high morbidity model for epilepsy termed the reduced intensity status epilepticus (RISE) model was developed to study temporal lobe epilepsy. Investigation of the early stages of epileptogenesis involved ex vivo local field potential (LFP) and whole-cell patch clamp recordings of extracted brain slices from RISE animals during the latent period (weeks 2, 3, 4, 5, and 6 post-induction) and during the SRS stage of epileptogenesis (>3 months post-induction). Using several measures of brain excitability, it was found there is a marked reduction in brain excitability for RISE animals during the later stages of epileptogenesis (weeks 4 – 6 post-induction) compared to aged-matched control (AMC) in hippocampal subregions CA1 and CA3. However, there appears to be recovery to AMC or even above as animals enter SRS despite now displaying electrographic and behavioural seizures. Previous work studying the RISE model of epilepsy has uncovered a dramatic loss of the glutamatergic ionotropic AMPA receptors (AMPARs) and their associated accessory proteins in the hippocampus during the latent period which continues into SRS. Tianeptine is an atypical anti-depressant which is already known to modulate AMPAR function by increasing channel conductance and by increasing AMPAR trafficking and anchoring into the postsynaptic membrane. Control experiments confirmed this by revealing a marked increase in hippocampal gamma oscillatory power when conducting LFP experiments across all ages studied. Given the proposed mechanism of action of tianeptine, tianeptine (10µM) was then studied as a potential anti-epileptogenic drug to modify the progression of epileptogenesis within the RISE model. Ex vivo LFP and patch clamp recordings were taken and found tianeptine was able to recover the hippocampal oscillation during the early stages of epileptogenesis but had subregional differences as the epileptogenesis progressed. Under both spontaneous and kainic acid (KA) conditions, tianeptine had minimal effects on the gamma oscillations in both hippocampal subregions CA1 and CA3 during the latent period (6 weeks post-induction) compared to AMC. However, once RISE animals enter SRS, tianeptine was only capable of modulating gamma oscillations in CA1 (and not CA3) in KA conditions. Therefore, showing subregional differences in the progression of epileptogenesis. Finally, to explore seizure susceptibility, the 0 Mg2+ in vitro model of epilepsy was employed in the hippocampus. Using several measures, it was found RISE animals were more susceptible to generate seizures and seizure-like activity. Seizure susceptibility decreased as RISE animals entered later into the latent period (weeks 5 – 6 post-induction) and again increased as they entered SRS. This combines with the above findings of reduced brain excitability during the latent period which likely drives the progression of epileptogenesis into SRS. Overall, this thesis shows there are dynamical changes in neuronal network function which underlie epileptogenesis in the temporal lobe
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
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