930 resultados para blue jets


Relevância:

20.00% 20.00%

Publicador:

Resumo:

Portunid crabs are an important resource in estuaries, and require appropriate management to guarantee their long-term availability. We investigated the population dynamics and reproduction of Callinectes danae in the Estuarine-Bay Complex of Sao Vicente, Sao Paulo, Brazil, to provide basic biological information for public policies for the management of this fishery. Monthly samples were obtained from March 2007 to February 2008 on eight transects, four in the estuary and four in the bay. A total of 2261 specimens (403 males, 1288 females, of which 570 were ovigerous) were collected. Males were significantly larger than females, and the size-frequency distribution was unimodal for males, females and ovigerous females. The sex ratio was nearly always skewed toward females (M:F - 1:4.6). C. danae showed seasonal-continuous reproduction, with high reproductive activity in the warmer season. C. danae breeds in the estuarine-bay complex, with males and juvenile females concentrated in the estuary. After copulation, fertilized females migrate to the estuary entrance and the bay, where ovigerous females are commonly found spawning in high-salinity areas. Therefore, to manage this important economic resource, both the estuary and the bay should be considered for protection, but special attention should be given to the estuary entrance during the summer months, when ovigerous females concentrate.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

This paper describes the preparation, characterization, and use of poly (methylene blue) (PMB)-modified glassy carbon electrodes (GCE) (GCE-PMB) in the detection of the thiols L-cysteine (L-CySH) and N-acetyl cysteine (Acy), and the herbicide glyphosate (GLYP) in pH 5.3 aqueous solution. The polymer film prepared by electropolymerization showed different characteristics such as robustness, stability, and redox properties satisfactorily. The surface coverage concentration (Gamma) of PMB was found to be 7.90 x 10(-9) - mol cm(-2). Moreover, we observed strong adhesion of the polymer film to the electrode surface. The results using GCE-PMB as a sensor indicated that this modified electrode exhibited electrocatalytic activity toward the detection of thiols and glyphosate in 0.1 mol L-1 KO (pH 5.3). Meanwhile, strong adsorption of the analytes on the GCE-PMB electrodes was also observed. Otherwise, using a low concentration (1 x 10(-4) mol L-1) of L-cysteine and N-acetyl cysteine and 8.9 x 10(-6) mol L-1 of glyphosate, separately, it was possible to observe a well-defined electrochemical response, thus providing an opportunity to further understand the applicability of PMB as a sensor for amino acid-based molecules. (C) 2012 Elsevier B.V. All rights reserved.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Today it is known that severe burns can be accompanied by the phenomenon of vasoplegic syndrome (VS), which is manifested by persistent and diffuse vasodilation, hypotension and low vascular resistance, resulting in circulatory and respiratory failure. The decrease in systemic vascular resistance observed in VS is associated with excessive production of nitric oxide (NO). In the last 2 decades, studies have reported promising results from the administration of an NO competitor, methylene blue (MB), which is an inhibitor of the soluble guanylate cyclase (sGC), in the treatment of refractory cases of vasoplegia. This medical hypothesis rationale is focused on the tripod of burns/vasoplegia catecholamine resistant/methylene blue. This article has 3 main objectives: 1) to study the guanylate cyclase inhibition by MB in burns; 2) to suggest MB as a viable, safe and useful co-adjuvant therapeutic tool of fluid resuscitation, and; 3) to suggest MB as burns hypotensive vasoplegia amine-resistant treatment.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

In a previous work, succinylated sugarcane bagasse (SCB 2) was prepared from sugarcane bagasse (B) using succinic anhydride as modifying agent. In this work the adsorption of cationic dyes onto SCB 2 from aqueous solutions was investigated. Methylene blue, MB, and gentian violet, GV, were selected as adsorbates. The capacity of SCB 2 to adsorb MB and GV from aqueous single dye solutions was evaluated at different contact times, pH, and initial adsorbent concentration. According to the obtained results, the adsorption processes could be described by the pseudo-second-order kinetic model. Adsorption isotherms were well fitted by Langmuir model. Maximum adsorption capacities for MB and GV onto SCB 2 were found to be 478.5 and 1273.2 mg/g, respectively. (C) 2011 Elsevier Ltd. All rights reserved.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Background: Brilliant blue G (BBG) is frequently used in chromovitrectomy to facilitate internal limiting membrane (ILM) peeling. A study was initiated to evaluate if heavy BBG is safe and effective in staining the ILM. Methods: We studied 30 eyes, 23 with idiopathic macular holes and 7 of patients with diabetic macular edema. Removal of the ILMs was assisted by heavy BBG staining. In cases with histopathological correlation the ILMs were evaluated with hematoxylin and eosin, Masson's trichrome, periodic acid-Schiff and glial fibrillary acidic protein staining. In addition, immunohistochemistry was also performed using specific antibodies for vimentin, neuron-specific enolase, factor VIII and CD68. Using the Image-Pro Plus software of Media Cybernetics Co. we found an average thickness in ILMs. Results: Of the ILM specimens sent, 19/30(63.33%) could not be processed properly because of the limited sample material, recognizing only fragments of dispersed fibrillar material. In macular hole ILMs we found an average thickness of 1.3 +/- 0.65 mu m, and in diabetic macular edema ILMs an average thickness of 6.2 +/- 1.4 mu m. Conclusions: In heavy BBG-assisted ILM peeling we observed no intraoperative or postoperative complications after a mean follow-up of 12 months. Heavy BBG could be an effective and safe vehicle for staining the ILM. Copyright (C) 2012 S. Karger AG, Basel

Relevância:

20.00% 20.00%

Publicador:

Resumo:

MgTiO3 (MTO) thin films were prepared by the polymeric precursor method with posterior spin-coating deposition. The films were deposited on Pt(111)/Ti/SiO2/Si(100) substrates and heat treated at 350 degrees C for 2 h and then heat treated at 400, 450, 500, 550, 600, 650 and 700 C for 2 h. The degree of structural order disorder, optical properties, and morphology of the MTO thin films were investigated by X-ray diffraction (XRD), micro-Raman spectroscopy (MR), ultraviolet-visible (UV-vis) absorption spectroscopy, photoluminescence (PL) measurements, and field-emission gun scanning electron microscopy (FEG-SEM) to investigate the morphology. XRD revealed that an increase in the annealing temperature resulted in a structural organization of MTO thin films. First-principles quantum mechanical calculations based on density functional theory (B3LYP level) were employed to study the electronic structure of ordered and disordered asymmetric models. The electronic properties were analyzed, and the relevance of the present theoretical and experimental results was discussed in the light of PL behavior. The presence of localized electronic levels and a charge gradient in the band gap due to a break in the symmetry are responsible for the PL in disordered MTO lattice.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

PURPOSE: To investigate the possible effect of aspherical or yellow tinted intraocular lens (IOL) on contrast sensitivity and blue-on-yellow perimetry. METHODS: This prospective randomized bilateral double-masked clinical study included 52 patients with visually significant bilateral cataracts divided in two groups; 25 patients (50 eyes) received aspherical intraocular lens in one eye and spherical intraocular lens in the fellow eye; and 27 patients (54 eyes) received ultraviolet and blue light filter (yellow tinted) IOL implantation in one eye and acrylic ultraviolet filter IOL in the fellow eye. The primary outcome measures were contrast sensitivity and blue-on-yellow perimetry values (mean deviation [MD] and pattern standard deviation [PSD]) investigated two years after surgery. The results were compared intra-individually. RESULTS: There was a statistically significant between-group (aspherical and spherical intraocular lens) difference in contrast sensitivity under photopic conditions at 12 cycles per degree and under mesopic conditions at all spatial frequencies. There were no between-group significant differences (yellow tinted and clear intraocular lens) under photopic or mesopic conditions. There was no statistically significant difference between all intraocular lens in MD or PSD. CONCLUSION: Contrast sensitivity was better under mesopic conditions with aspherical intraocular lens. Blue-on-yellow perimetry did not appear to be affected by aspherical or yellow tinted intraocular lens. Further studies with a larger sample should be carried out to confirm or not that hypotheses.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The aim of this study was to compare the disinfection of dentine using photodynamic therapy with methylene blue in different formulations. Thirty bovine teeth roots were autoclaved and incubated with a suspension of Enterococcus faecalis. The specimen were randomly divided into three groups: G1, the roots were filled with 10 mM methylene blue dissolved in water; G2, the roots were filled with 10 mM methylene blue dissolved in a mixture of glycerol: ethanol: water; G3, roots filled with 100 mM methylene blue dissolved in water. The groups were irradiated with a 660 nm diode laser with an output power of 100 mW for 4 min, energy density of 850 J/cm2 and after this procedure, the sensitizer was removed and microbial samples were collected from within the root canals. The samples were plated on mEnterococcus to count the colony-forming units (CFU/mL). The means were: Group 1=513×103, Group 2=1431×103 and Group 3=2.96×103. The statistical analysis detected higher disinfection achieved by G3 when compared with groups G1 and G2, and no significant difference between the groups G1 and G2 (P>0.05). The increase of the concentration of methylene blue dye achieved higher disinfection in photodynamic therapy.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Two types of mesoscale wind-speed jet and their effects on boundary-layer structure were studied. The first is a coastal jet off the northern California coast, and the second is a katabatic jet over Vatnajökull, Iceland. Coastal regions are highly populated, and studies of coastal meteorology are of general interest for environmental protection, fishing industry, and for air and sea transportation. Not so many people live in direct contact with glaciers but properties of katabatic flows are important for understanding glacier response to climatic changes. Hence, the two jets can potentially influence a vast number of people. Flow response to terrain forcing, transient behavior in time and space, and adherence to simplified theoretical models were examined. The turbulence structure in these stably stratified boundary layers was also investigated. Numerical modeling is the main tool in this thesis; observations are used primarily to ensure a realistic model behavior. Simple shallow-water theory provides a useful framework for analyzing high-velocity flows along mountainous coastlines, but for an unexpected reason. Waves are trapped in the inversion by the curvature of the wind-speed profile, rather than by an infinite stability in the inversion separating two neutral layers, as assumed in the theory. In the absence of blocking terrain, observations of steady-state supercritical flows are not likely, due to the diurnal variation of flow criticality. In many simplified models, non-local processes are neglected. In the flows studied here, we showed that this is not always a valid approximation. Discrepancies between simulated katabatic flow and that predicted by an analytical model are hypothesized to be due to non-local effects, such as surface inhomogeneity and slope geometry, neglected in the theory. On a different scale, a reason for variations in the shape of local similarity scaling functions between studies is suggested to be differences in non-local contributions to the velocity variance budgets.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The overall aim of the present thesis was to develop and characterise an age assessment method based on incremental lines in dental cementum using contemporary bovine teeth and teeth from archaeological faunal assemblages. The investigations also included two other age assessment methods: tooth wear pattern and macroscopic dental measurements. The first permanent mandibular molar and lower jaws from 70 contemporary cattle of known age and 170 archaeological molar sets from ten different Swedish archaeological sites were used. The following conclusions were drawn: • The number of incremental lines in the dental cementum varied between different parts of the tooth root as well as within one and the same individual. The results from contemporary cattle of known age showed a strong relationship between age and incremental lines in the cementum of the distal part of the mesial root (R2=65.5%) and the known ages of the animals. • With the “best” model variation in age could be explained to 65.5% (R2) by the number of incremental lines. Thus, the remaining age variation (approximately 35%) could not be explained by these lines. Other factors than must thus be responsible. However, with the exception of calves born the present material did not reveal any such significant relationship. • The results from cattle of known age indicate that the method of assessing age on the basis of cemental incremental lines is more reliable than other methods such as tooth wear or tooth measurements. However, by combining counting incremental lines and one variable assessing tooth dimension (tooth height) a slightly stronger relationship could be obtained (R2=74.5%). The results from age assessment of the medieval and post-Reformation cattle emphasize the importance of supplementing any age estimation of archaeological assemblages based on dental indicators with characteristics for the particular assessment model. Furthermore, conclusions based on age assessment with such models can not be drawn with any more detailed time scale than about 2 years leaving at best only 25% (R2) of factors influencing the dental indicator(s) utilized in the model unexplained. The accuracy of the age assessment required by the particular historical context in which the archaeological remains are found should thus decide what level of accuracy should be chosen.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Miquel Becerro es científico del Instituto de Productos Naturales y Agrobiología -IPNA- (CSIC)

Relevância:

20.00% 20.00%

Publicador:

Resumo:

The velocity and mixing field of two turbulent jets configurations have been experimentally characterized by means of cold- and hot-wire anemometry in order to investigate the effects of the initial conditions on the flow development. In particular, experiments have been focused on the effect of the separation wall between the two streams on the flow field. The results of the experiments have pointed out that the wake behind a thick wall separating wall has a strong influence on the flow field evolution. For instance, for nearly unitary velocity ratios, a clear vortex shedding from the wall is observable. This phenomenon enhances the mixing between the inner and outer shear layer. This enhancement in the fluctuating activity is a consequence of a local absolute instability of the flow which, for a small range of velocity ratios, behaves as an hydrodynamic oscillator with no sensibility to external perturbations. It has been suggested indeed that this absolute instability can be used as a passive method to control the flow evolution. Finally, acoustic excitation has been applied to the near field in order to verify whether or not the observed vortex shedding behind the separating wall is due to a global oscillating mode as predicted by the theory. A new scaling relationship has been also proposed to determine the preferred frequency for nearly unitary velocity ratios. The proposed law takes into account both the Reynolds number and the velocity ratio dependence of this frequency and, therefore, improves all the previously proposed relationships.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

Blue straggler stars (BSSs) are brighter and bluer (hotter) than the main-sequence (MS) turnoff and they are known to be more massive than MS stars.Two main scenarios for their formation have been proposed:collision-induced stellar mergers (COL-BSSs),or mass-transfer in binary systems (MT-BSSs).Depleted surface abundances of C and O are expected for MT-BSSs,whereas no chemical anomalies are predicted for COL-BSSs.Both MT- and COL-BSSs should rotate fast, but braking mechanisms may intervene with efficiencies and time-scales not well known yet,thus preventing a clear prediction of the expected rotational velocities.Within this context,an extensive survey is ongoing by using the multi-object spectrograph FLAMES@VLT,with the aim to obtain abundance patterns and rotational velocities for representative samples of BSSs in several Galactic GCs.A sub-population of CO-depleted BSSs has been identified in 47 Tuc,with only one fast rotating star detected.For this PhD Thesis work I analyzed FLAMES spectra of more than 130 BSSs in four GCs:M4,NGC 6397,M30 and ω Centauri.This is the largest sample of BSSs spectroscopically investigated so far.Hints of CO depletion have been observed in only 4-5 cases (in M30 and ω Centauri),suggesting either that the majority of BSSs have a collisional origin,or that the CO-depletion is a transient phenomenon.Unfortunately,no conclusions in terms of formation mechanism could be drawn in a large number of cases,because of the effects of radiative levitation. Remarkably,however,this is the first time that evidence of radiative levitation is found in BSSs hotter than 8200 K.Finally, we also discovered the largest fractions of fast rotating BSSs ever observed in any GCs:40% in M4 and 30% in ω Centauri.While not solving the problem of BSS formation,these results provide invaluable information about the BSS physical properties,which is crucial to build realistic models of their evolution.

Relevância:

20.00% 20.00%

Publicador:

Resumo:

In hadronischen Kollisionen entstehen bei einem Großteil der Ereignisse mit einem hohen Impulsübertrag Paare aus hochenergetischen Jets. Deren Produktion und Eigenschaften können mit hoher Genauigkeit durch die Störungstheorie in der Quantenchromodynamik (QCD) vorhergesagt werden. Die Produktion von \textit{bottom}-Quarks in solchen Kollisionen kann als Maßstab genutzt werden, um die Vorhersagen der QCD zu testen, da diese Quarks die Dynamik des Produktionsprozesses bei Skalen wieder spiegelt, in der eine Störungsrechnung ohne Einschränkungen möglich ist. Auf Grund der hohen Masse von Teilchen, die ein \textit{bottom}-Quark enthalten, erhält der gemessene, hadronische Zustand den größten Teil der Information von dem Produktionsprozess der Quarks. Weil sie eine große Produktionsrate besitzen, spielen sie und ihre Zerfallsprodukte eine wichtige Rolle als Untergrund in vielen Analysen, insbesondere in Suchen nach neuer Physik. In ihrer herausragenden Stellung in der dritten Quark-Generation könnten sich vermehrt Zeichen im Vergleich zu den leichteren Quarks für neue Phänomene zeigen. Daher ist die Untersuchung des Verhältnisses zwischen der Produktion von Jets, die solche \textit{bottom}-Quarks enthalten, auch bekannt als $b$-Jets, und aller nachgewiesener Jets ein wichtiger Indikator für neue massive Objekte. In dieser Arbeit werden die Produktionsrate und die Korrelationen von Paaren aus $b$-Jets bestimmt und nach ersten Hinweisen eines neuen massiven Teilchens, das bisher nicht im Standard-Modell enthalten ist, in dem invarianten Massenspektrum der $b$-Jets gesucht. Am Large Hadron Collider (LHC) kollidieren zwei Protonenstrahlen bei einer Schwerpunktsenergie von $\sqrt s = 7$ TeV, und es werden viele solcher Paare aus $b$-Jets produziert. Diese Analyse benutzt die aufgezeichneten Kollisionen des ATLAS-Detektors. Die integrierte Luminosität der verwendbaren Daten beläuft sich auf 34~pb$^{-1}$. $b$-Jets werden mit Hilfe ihrer langen Lebensdauer und den rekonstruierten, geladenen Zerfallsprodukten identifiziert. Für diese Analyse müssen insbesondere die Unterschiede im Verhalten von Jets, die aus leichten Objekten wie Gluonen und leichten Quarks hervorgehen, zu diesen $b$-Jets beachtet werden. Die Energieskala dieser $b$-Jets wird untersucht und die zusätzlichen Unsicherheit in der Energiemessung der Jets bestimmt. Effekte bei der Jet-Rekonstruktion im Detektor, die einzigartig für $b$-Jets sind, werden studiert, um letztlich diese Messung unabhängig vom Detektor und auf Niveau der Hadronen auswerten zu können. Hiernach wird die Messung zu Vorhersagen auf nächst-zu-führender Ordnung verglichen. Dabei stellt sich heraus, dass die Vorhersagen in Übereinstimmung zu den aufgenommenen Daten sind. Daraus lässt sich schließen, dass der zugrunde liegende Produktionsmechanismus auch in diesem neu erschlossenen Energiebereich am LHC gültig ist. Jedoch werden auch erste Hinweise auf Mängel in der Beschreibung der Eigenschaften dieser Ereignisse gefunden. Weiterhin können keine Anhaltspunkte für eine neue Resonanz, die in Paare aus $b$-Jets zerfällt, in dem invarianten Massenspektrum bis etwa 1.7~TeV gefunden werden. Für das Auftreten einer solchen Resonanz mit einer Gauß-förmigen Massenverteilung werden modell-unabhängige Grenzen berechnet.