1,720,972 research outputs found
Visualization of amplified ribosomal gene activity in oogenesis of Reticulitermes lucifugus (Isoptera: Rhinotermitidae) revealed by silver staining.
No full textThe Ag-pattern of amplified nucleolar material in various stages of R. lucifugus oogenesis has been followe
Patterns of activity of nucleolar organizer regions during spermatogenesis and oogenesis in Kalotermes flavicollis Fabr. (Insecta: Isoptera) analyzed by silver staining
No full textThe distribution and the behaviour of the nucleolus organizer regions (NORs) were analysed during the spermatogenesis and oogenesis of K. flavicollis with the silver staining method. The Ag-stainability of the NORs increases in growing spermatocytes up to pachytene and is absent during the remainder of the meiotic prophase. During female meiosis the nucleolar material undergoes a more complex transformation. It is active until pachytene; in early diplotene the mass of silver stainable material progressively increases as an effect of rDNA amplification. By the end of meiotic prophase the nucleolar strands disappear and a large nucleolus is rebuilt in the mature oocyte
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
Silver staining of synaptonemal complexes in surface-spreading spermatocytes of fallow deer (Dama dama L.).
No full textSurface-spread spermatocytes of the fallow deer were examined by light microscopy after silver staining. The development and behaviour of synaptonemal complexes and the partial synapsis of the X and Y chromosomes were investigated during leptotene to diplotene chromosome pairing
Cytogenetic studies on Cervus elaphus - II. Synaptonemal complexes and NOR activity during spermatogenesis
No full textThe activity of the nucleolus organizer regions (NORs) in various stages of spermatogenesis of the red deer was studied with the silver staining technique. The Ag-stainability of the NORs, an indicator of the transcriptional activity of the r-RNA genes, is present during the meiotic prophase until pachytene and is absent during the remainder of the meiotic prophase, to reappear during the first stages of spermiogenesis and then disappear again during the elongation phase of the spermatids.
The development and behaviour of synaptonemal complexes (SCs) of primary spermatocytes were also studied with the silver staining technique under the light microscope. The organization of SC is similar to that of other mammalian species. The pairing behaviour of the axes of the sex chromosomes is described
Towards a Temperature Compensated Model for a Blood-pH Sensor in Extracorporeal Circulation
No full textUnder physiological conditions, the body maintains blood pH within the very narrow range [7.36, 7.44] pH. Small deviations from this range can reveal the onset of pathological states. In this work the performances of a real-time, non-invasive pH measuring sysem for extracorporeal circulation (ECC) are analyzed. In particular, this study focuses on the analysis of the effects that temperature of the measurand may have on the error in estimating blood pH. Indeed, the sensor is based on the analysis of the fluorescence produced by HPTS, which is known to vary with temperature. The extent of such a variation, however, depends on various factors, including the chemical environment. Blood temperature in ECC is often thermostated at 37 °C. Nevertheless, there are treatments in which the blood temperature is varied by a few Celsius degrees, generally reduced, from the physiological temperature of 37 °C. Therefore, the first objective of this study was to evaluate whether a modest reduction in temperature, that is a few Celsius degrees, introduce an error such as the measuring system no longer conforms to the maximum permissible measurement error of ±0.04 pH. Once verified that the temperature-induced error could exceed the limit of ±0.04 pH, a correction factor for temperature compensation was investigated and its robustness to unevenness in the sensor production was explored. The results obtained from this preliminary study performed using Phosphate Buffer Saline (PBS) showed how the addition to the measuring system of a temperature sensor can effectively allow to maintain the measurement error within the ±0.04 pH range, even when the temperature of the measurand decreases by a few degrees from the physiological temperature of 37 °C
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
Towards Continuous Nano-Plastic Monitoring in Water by High Frequency Impedance Measurement with Nano-Electrode Arrays
Full text linkWe explore the potentiality of high frequency impedance measurements with CMOS nano-electrode arrays for nano-plastic pollutant particles monitoring in water. This technology offers benefits as nano-scale resolution, high parallelization, scalability, label-free single particle detection, and automatic measurements without operator intervention. Simple models are proposed for size and concentration estimation. The former integrates measurements of adjacent electrodes and shows uncertainty comparable to the nominal one with mean prediction error lower than 45 % down to 50 nm radius. The latter accounts for noise in the definition of the sensing volume. We report a worst-case concentration error lower than a factor 1.7 under stationary and continuous flow, which demonstrates the potential of this technology for automated measurements
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