119,073 research outputs found
Droplet-induced optical effects in an opto-microfluidic cross-configuration system
No full textA comprehensive description of all the optical phenomena occurring when light interacts with a moving dispersed phase in a constrained environment such as a real microfluidic channel is needed to perform a quantitative analysis as well as predictive one. This requires identifying fingerprints in the detected optical signal that are doubtlessly correlated with the shape and content type of the dispersed phase from those connected to uncertainties of the optical detection systems and/or instabilities in the microfluidics apparatus leading to dispersed phase size distribution. This article aims to model all the droplet-induced optical effects in an opto-microfluidic cross-configuration system and quantify how diffraction, transmission, absorbance, and reflection contribute to the overall response in the detected intensity after light-matter interaction. The model has been tested in the case of water droplets dispersed in hexadecane continuous phase as generated in an opto-microfluidic platform where optical waveguides are fully integrated with the microfluidic channels, so that light illuminates the flowing droplets from the channel wall and collected on the opposite side. A critical discussion of the impact of geometry and constrains is proposed as well as the impact of each contribute in terms of fingerprints in the detected signal. The good agreement obtained demonstrates the potentialities of both the derived model and the cross-configuration, getting information on droplet characteristics from the intensity arising from its light interaction
Ramgen: a dual port static RAM generator
No full textAn automatic dual port static RAM (DPSRAM) generator based on a process-independent design methodology for double metal CMOS technology is described. An innovative architecture, using modular structures and cutoff transistors, has been designed to maintain the same performance independent of the array size, and to minimize the basic cell area. The use of the process-independent approach allows for an automatic mapping into different target CMOS technologies including submicron processes. Two DPSRAM blocks of 512 words by 8 b, included in a 100K-transistor cell-based design have been diffused and tested successfull
The Direct Renin Inhibitor Aliskiren Improves Vascular Remodeling in Transgenic Rats Harboring Human Renin and Angiotensinogen Genes
No full textObjective: The selective human renin inhibitor aliskiren (ALK) reduces blood pressure and ameliorates cardio-renal organ damage in hypertensive double transgenic rats (dTGRs) which express both human renin and angiotensinogen. Little is known about the effect of ALK on hypertension-related functional and structural alterations of resistance arteries. We tested the hypothesis that chronic treatment with ALK in dTGRs improves resistance arteries’ vascular remodeling which represents the earliest manifestation of target organ damage in hypertensive subjects and has prognostic significance.
Design and method: dTGRs (5 weeks old) were treated with ALK (3 mg/kg/day, n=5) or ramipril (RAM, 1 mg/kg/day, n=5) for 14 days and compared with age-matched untreated dTGRs. Blood pressure (BP) was measured by tail-cuff method. Resistance arteries media-to-lumen ratio (M/L) was evaluated on mesenteric arteries as pressurized preparations. Endothelium-dependent and -independent relaxations were assessed by dose-responses curves to acetylcholine (Ach, 10-9 to 10-4 mol/L) and sodium nitroprusside (SNP, 10-8 to 10-4 mol/L), respectively, in vessels precontracted with norepinephrine (10-6 mol/L). The expression of AT1 receptor, AT2 receptor, eNOS and the NADPH subunit gp91phox in aorta was evaluated by immunoblotting. The reactive oxygen species (ROS) production was evaluated in aorta by Dihydroethidium (DHE) staining.
Results and conclusions: BP was similarly reduced in both ALK-treated and RAM-treated rats compared to untreated dTGRs (167±1.18 mmHg and 169.4±1.5 mmHg vs 196.8 ±3.9 mmHg, respectively P<0.05; reduction of -15% and -14%; P<0.05). M/L was equally reduced in ALK-treated and RAM-treated rats compared to untreated rats (6.3±0.5 % and 6.4±0.2 % vs 9.8±.04%, respectively; P<0.05). Endothelium-dependent and –independent relaxations were not different between ALK-treated and RAM-treated dTGRs. AT1 and AT2 receptor expression was similar in all the groups. eNOS expression was increased only in ALK-treated rats (+41.3±6.3 % vs untreated dTGRs, p<0.05). gp91phox was slightly reduced in both ALK-and RAM-treated dTGRs. Both ALK and RAM similarly reduced ROS production in dTGRs compared to untreated rats (14.7±0.2 AU and 13.9±0.3 AU vs 18.1±0.9 AU, respectively; p<0.05).
In conclusion equieffective antihypertensive dose of ALK or RAM improved oxidative stress and reduced M/L of mesenteric arteries. Only ALK increased the eNOS bioavailability. Hence, in dTGRs renin inhibition compares favorably to ACE inhibition in improving vascular remodeling
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Uncovering a Role for the Tail of the Dictyostelium discoideum SadA Protein in Cell-Substrate Adhesion
No full textABSTRACTPrevious work from our laboratory showed that theDictyostelium discoideumSadA protein plays a central role in cell-substrate adhesion. SadA null cells exhibit a loss of adhesion, a disrupted actin cytoskeleton, and a cytokinesis defect. How SadA mediates these phenotypes is unknown. This work addresses the mechanism of SadA function, demonstrating an important role for the C-terminal cytoplasmic tail in SadA function. We found that a SadA tailless mutant was unable to rescue thesadAadhesion deficiency, and overexpression of the SadA tail domain reduced adhesion in wild-type cells. We also show that SadA is closely associated with the actin cytoskeleton. Mutagenesis studies suggested that four serine residues in the tail, S924/S925 and S940/S941, may regulate association of SadA with the actin cytoskeleton. GlutathioneS-transferase pull-down assays identified at least one likely interaction partner of the SadA tail, cortexillin I, a known actin bundling protein. Thus, our data demonstrate an important role for the carboxy-terminal cytoplasmic tail in SadA function and strongly suggest that a phosphorylation event in this tail regulates an interaction with cortexillin I. Based on our data, we propose a model for the function of SadA.</jats:p
The epithalamus of the developing and adult frogs: calretinin expression and habenular asymmetry in Rana esculenta
No full textOpto-Microfluidic Integration of the Bradford Protein Assay in Lithium Niobate Lab-On-A-Chip
No full textThis paper deals with the quantification of proteins by implementing the Bradford protein assay method in a portable opto-microfluidic platform for protein concentrations lower than 1.4 mg/mL. Absorbance is measured by way of optical waveguides integrated to a cross-junction microfluidic circuit on a single lithium niobate substrate. A new protocol is proposed to perform the protein quantification based on the high correlation of the light absorbance at 595 nm, as commonly used in the Bradford method, with the one achieved at 633 nm with a cheap commercially available diode laser. This protocol demonstrates the possibility to quantify proteins by using nL volumes, 1000 times less than the standard technique such as paper-analytical devices. Moreover, it shows a limit of quantification of at least 0.12 mg/mL, which is four times lower than the last literature, as well as a better accuracy (98%). The protein quantification is obtained either by using one single microfluidic droplet as well by performing statistical analysis over ensembles of several thousands of droplets in less than 1 min. The proposed methodology presents the further advantage that the protein solutions can be reused for other investigations and the same pertains to the opto-microfluidic platform
Square Dancing with the Stars to Enhance Dynamic Hirschman Linkages?
No full textIn this Presidential Address, the author takes the reader on a reconnaissance of his life and time as a regional scientist. He points out scenery he found scintillating along the way, hoping that some may pick up the banner and chew on a few of the ideas for a while. He suggests a revisit to Albert O. Hirschman’s notion of key sectors and more empirical analysis related to Marcus Berliant’s and Masahisa Fujita’s notion of knowledge creation and transfer.Presidential Address, San Antonio, Texas, March 29, 2014 (53rd Meetings of the Southern Regional Science Association
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe 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
Sol-gel deposition of silica films on silicate glasses: Influence of the presence of lead in the glass or in precursor solutions
No full textMany lead silicate historical glasses suffer degradation phenomena often observed as color changes and iridescence caused by lead ions leaching from the outer layers of the glass. In order to repair and to prevent these phenomena, glasses with large amounts of lead (6.7 and 14.3 at.% of lead) have been coated with silica films at neutral pH by dipping them in a precursor solution of TEOS (tetraethyl orthosilicate), ethyl alcohol and deionized water without any other acid or basic catalyst. Experiments with long dipping times (24 h) and temperatures around 20 °C have been performed to evaluate the role of lead ions of the glass as a catalyst. Silica films of very good quality and optical transparency have been also obtained on lead-free, soda-lime glasses by adding catalytic amounts of Pb(NO3)2 instead of HCl to the precursor solution. The films have been characterized by optical microscopy, AFM (Atomic Force Microscopy), XPS (X-ray Photoelectron Spectroscopy) and SIMS (Secondary Ion Mass Spectrometry)
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