Niveles de interacción en la comunicación en Internet

Este trabajo presenta una categorización de los niveles de interacción que los usuarios de Internet establecen entre ellos mismos y con la tecnología que los convoca. Se plantea queaquellos flujos informativos y comunicacionales que circulan en Internet son variados y diversos y que están determinados no sólo por las características técnicas del equipamiento y los soportes materiales, sino, fundamentalmente, por las competencias de los usuarios, a través de las cuales se realiza más de un proceso de comunicación.This paper presents a chart of interaction levels on Internet users. These levels are established among themselves and the technology that summons the users. The investigation states that the communicational flows that circulate in Internet are varied, diverse and are determined by technologic characteristics of the equipment and material support but, fundamentally by the competition of the users. During these process, the users materialize more than one act of communication

Learning curve in circular multipolar phased radiofrequency ablation of atrial fibrillation

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Learning curve in circular multipolar phased radiofrequency ablation of atrial fibrillation

Background: Although atrial fibrillation (AF) ablation is considered a technically challenging procedure, studies on the learning curve of different pulmonary vein isolation (PVI) techniques are limited. We investigated the time-dependent changes in procedural parameters, complication rates, and in the 1-year clinical outcome during our initial experience with circular multipolar phased radiofrequency (RF) ablation. Methods and results: The first 132 consecutive patients (40 female; age: 56.6 ± 10.4 years) who underwent PVI with phased RF ablation for paroxysmal or persistent AF at our center were included in the study. Procedural parameters and atrial arrhythmia-free survival were compared in the first, second and third group of 44 successive patients. All pulmonary veins were successfully isolated in 44 (100%), 41 (93.8%) and 42 (95.5%) patients in Tierce 1, 2 and 3, respectively (p = 0.233). The number of RF applications (per vein) required for isolation and fluoroscopy times demonstrated a significant decrease with experience, and a trend towards lower procedure times in Tierces 2 and 3 was also observed. Atrial arrhythmia-free survival rates at 12 months postablation were 68.18%, 75%, and 70.75% in Tierce 1, Tierce 2 and Tierce 3, respectively (p = 0.772). Pericardial tamponade requiring percutaneous subxi­phoid drainage occurred in 1 patient (Tierce 3) as the only significant procedural complication. Conclusions: A learning curve effect was demonstrated in fluoroscopy times and in the number of RF applications but not in the acute success and in the long-term arrhythmia-free survival with circular multipolar RF ablations.

Poli(etilén-tereftalát) bontása visszaforgatható organokatalizátorok segítségével: Depolymerization of poly(ethylene terephthalate) in the presence of recyclable organocatalysts

Recycling of plastic materials has an important role in the twenty-first century in reducing environmental pollution and saving petroleum resources. Poly(ethylene terephthalate) (PET) provides one of the best examples for this as it is a non-biodegradable polymer that is mainly used as raw material for a wide range of packaging applications, making degradation of PET a subject of great interest for researchers. In our work, post-consumer PET bottles were degraded with glycolysis into bis(2-hydroxyethyl) terephthalate (BHET) monomer using commercially available functionalized silica gels or 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) immobilized on silica gel. After the most stable and active catalyst was found to be triethyl amine functionalized silica gel, the optimization of reaction parameters was carried out. The silica gel as solid support helps in recycling the applied organic base making this process sustainable. Kivonat A műanyagok újrahasznosítása rendkívüli fontosságú a huszonegyedik században, mind a környezetszennyezés csökkentése, mind pedig a meg nem újuló energiaforrások megtakarítása miatt. A poli(etilén-tereftalát) (PET) az egyik legjobb példa erre, mivel ez egy biológiailag nem lebomló polimer, melyet főleg csomagoláshoz használnak fel széles körben, ezért ennek a műanyagnak a lebontása nagy érdeklődést váltott ki a kutatókból. Munkánk során használt PET-palackokat bontottunk le glikolízissel bisz(2-hidroxietil)-tereftalát (BHET) monomerré kereskedelmi forgalomban kapható funkcionalizált szilikagél, vagy szilikagélhez rögzített 1,5,7-triazabiciklo[4.4.0]dec-5-ént (TBD) katalizátorokat alkalmazva. Miután azt találtuk, hogy a legstabilabb és legaktívabb katalizátor a trietil-amin funkcionalizált szilikagél, optimalizáltuk a reakcióparamétereket. A szilikagél szilárd hordozóként lehetővé teszi az alkalmazott szerves bázis visszaforgatását, így fenntarthatóvá téve a folyamatot

Ecto-nucleoside triphosphate diphosphohydrolase 3 in the ventral and lateral hypothalamic area of female rats: morphological characterization and functional implications

<p>Abstract</p> <p>Background</p> <p>Based on its distribution in the brain, ecto-nucleoside triphosphate diphosphohydrolase 3 (NTPDase3) may play a role in the hypothalamic regulation of homeostatic systems, including feeding, sleep-wake behavior and reproduction. To further characterize the morphological attributes of NTPDase3-immunoreactive (IR) hypothalamic structures in the rat brain, here we investigated: 1.) The cellular and subcellular localization of NTPDase3; 2.) The effects of 17β-estradiol on the expression level of hypothalamic NTPDase3; and 3.) The effects of NTPDase inhibition in hypothalamic synaptosomal preparations.</p> <p>Methods</p> <p>Combined light- and electron microscopic analyses were carried out to characterize the cellular and subcellular localization of NTPDase3-immunoreactivity. The effects of estrogen on hypothalamic NTPDase3 expression was studied by western blot technique. Finally, the effects of NTPDase inhibition on mitochondrial respiration were investigated using a Clark-type oxygen electrode.</p> <p>Results</p> <p>Combined light- and electron microscopic analysis of immunostained hypothalamic slices revealed that NTPDase3-IR is linked to ribosomes and mitochondria, is predominantly present in excitatory axon terminals and in distinct segments of the perikaryal plasma membrane. Immunohistochemical labeling of NTPDase3 and glutamic acid decarboxylase (GAD) indicated that γ-amino-butyric-acid- (GABA) ergic hypothalamic neurons do not express NTPDase3, further suggesting that in the hypothalamus, NTPDase3 is predominantly present in excitatory neurons. We also investigated whether estrogen influences the expression level of NTPDase3 in the ventrobasal and lateral hypothalamus. A single subcutaneous injection of estrogen differentially increased NTPDase3 expression in the medial and lateral parts of the hypothalamus, indicating that this enzyme likely plays region-specific roles in estrogen-dependent hypothalamic regulatory mechanisms. Determination of mitochondrial respiration rates with and without the inhibition of NTPDases confirmed the presence of NTPDases, including NTPDase3 in neuronal mitochondria and showed that blockade of mitochondrial NTPDase functions decreases state 3 mitochondrial respiration rate and total mitochondrial respiratory capacity.</p> <p>Conclusion</p> <p>Altogether, these results suggest the possibility that NTPDases, among them NTPDase3, may play an estrogen-dependent modulatory role in the regulation of intracellular availability of ATP needed for excitatory neuronal functions including neurotransmission.</p