Expressiveness and definability in circumscription

We investigate expressiveness and definability issues with respect to minimal models, particularly in the scope of Circumscription. First, we give a proof of the failure of the Löwenheim-Skolem Theorem for Circumscription. Then we show that, if the class of P; Z-minimal models of a first-order sentence is 16;-elementary, then it is elementary. That is, whenever the circumscription of a first-order sentence is equivalent to a first-order theory, then it is equivalent to a finitely axiomatizable one. This means that classes of models of circumscribed theories are either elementary or not 16;-elementary. Finally, using the previous result, we prove that, whenever a relation Pi is defined in the class of P; Z-minimal models of a first-order sentence Φ and whenever such class of P; Z-minimal models is 16;-elementary, then there is an explicit definition ψ for Pi such that the class of P; Z-minimal models of Φ is the class of models of Φ ∧ ψ. In order words, the circumscription of P in Φ with Z varied can be replaced by Φ plus this explicit definition ψ for Pi.

DYNAMICS OF LEAF FALL FROM RIPARIAN VEGETATION AND THE ACCUMULATION IN BENTHIC STOCK IN NEOTROPICAL STREAMS1

ABSTRACT Considering the importance of the riparian vegetation leaves as an energetic source to first order streams, the aim of the present study was to evaluate the leaf biomass contribution to the system and its temporal dynamics. With this purpose, monthly samples from July 2008 to June 2009 were collected using four sampling devices installed in three streams, in order to collect the vertical, lateral and terrestrial loads, and the benthic stock. We tested the following hypothesis: (1) leaf biomass input is higher after hydric stress periods; and (2) benthic stock biomass increase with higher loads from vertical and lateral entrances. Leaves represented 71.9% (on average) of all sampled allochthonous matter, with seasonal significant variation along the studied year. Peaks of leaf input were registered in September-October, after an increase in rainfall, and also in January, after a decrease in rainfall. Leaf input was higher in the lateral load.

Development of capacitive sensor for measuring soil water content

The irrigation management based on the monitoring of the soil water content allows for the minimization of the amount of water applied, making its use more efficient. Taking into account these aspects, in this work, a sensor for measuring the soil water content was developed to allow real time automation of irrigation systems. This way, problems affecting crop yielding such as irregularities in the time to turn on or turn off the pump, and excess or deficit of water can be solved. To develop the sensors were used stainless steel rods, resin, and insulating varnish. The sensors measuring circuit was based on a microcontroller, which gives its output signal in the digital format. The sensors were calibrated using soil of the type “Quartzarenic Neosoil”. A third order polynomial model was fitted to the experimental data between the values of water content corresponding to the field capacity and the wilting point to correlate the soil water content obtained by the oven standard method with those measured by the electronic circuit, with a coefficient of determination of 93.17%, and an accuracy in the measures of ±0.010 kg kg-1. Based on the results, it was concluded that the sensor and its implemented measuring circuit can be used in the automation process of irrigation systems.

Measurement of antioxidant activity with trifluoperazine dihydrochloride radical cation

A novel, rapid and cost-effective trifluoperazine dihydrochloride (TFPH) decolorization assay is described for the screening of antioxidant activity. A chromogenic reaction between TFPH and potassium persulfate at low pH produces an orange-red radical cation with maximum absorption at 502 nm in its first-order derivative spectrum. TFPH was dissolved in distilled water to give a 100 mM solution. The TFPH radical cation solution was made by reacting 0.5 mL of the solution with K2S2O8 (final concentration: 0.1 mM) and diluting to 100 mL with 4 M H2SO4 solution. A linear inhibition of color production was observed with linearly increasing amounts of antioxidants, with correlation coefficients (R²) ranging from 0.999 to 0.983. The antioxidant capacity of standard solutions of an antioxidant was evaluated by comparing with the inhibition curve using Trolox as the standard. Comparison of antioxidant capacity determined with this newly developed TFPH assay and with the well-known 2,2'-azinobis-[3-ethylbenzthiazoline-6-sulfonic acid] (ABTS)-persulfate decolorization assay indicated the efficacy and sensitivity of the procedure. The proposed assay is less expensive (costs about US$4 per 100 assays) and requires only 20 min for preparation of radical cation solution in comparison with ABTS assay, in which almost 12-16 h are required for preparation of a stable ABTS radical cation solution. The present assay has the advantage over ABTS assay that it can be used to measure the antioxidant activity of the samples, which are naturally found at a pH as low as 1, because the radical cation itself has been stabilized at low pH.

A key role for Na+/K+-ATPase in the endothelium-dependent oscillatory activity of mouse small mesenteric arteries

Oscillatory contractile activity is an inherent property of blood vessels. Various cellular mechanisms have been proposed to contribute to oscillatory activity. Mouse small mesenteric arteries display a unique low frequency contractile oscillatory activity (1 cycle every 10-12 min) upon phenylephrine stimulation. Our objective was to identify mechanisms involved in this peculiar oscillatory activity. First-order mesenteric arteries were mounted in tissue baths for isometric force measurement. The oscillatory activity was observed only in vessels with endothelium, but it was not blocked by L-NAME (100 µM) or indomethacin (10 µM), ruling out the participation of nitric oxide and prostacyclin, respectively, in this phenomenon. Oscillatory activity was not observed in vessels contracted with K+ (90 mM) or after stimulation with phenylephrine plus 10 mM K+. Ouabain (1 to 10 µM, an Na+/K+-ATPase inhibitor), but not K+ channel antagonists [tetraethylammonium (100 µM, a nonselective K+ channel blocker), Tram-34 (10 µM, blocker of intermediate conductance K+ channels) or UCL-1684 (0.1 µM, a small conductance K+ channel blocker)], inhibited the oscillatory activity. The contractile activity was also abolished when experiments were performed at 20°C or in K+-free medium. Taken together, these results demonstrate that Na+/K+-ATPase is a potential source of these oscillations. The presence of α-1 and α-2 Na+/K+-ATPase isoforms was confirmed in murine mesenteric arteries by Western blot. Chronic infusion of mice with ouabain did not abolish oscillatory contraction, but up-regulated vascular Na+/K+-ATPase expression and increased blood pressure. Together, these observations suggest that the Na+/K+ pump plays a major role in the oscillatory activity of murine small mesenteric arteries.

Percutaneous sciatic nerve block with tramadol induces analgesia and motor blockade in two animal pain models

Local anesthetic efficacy of tramadol has been reported following intradermal application. Our aim was to investigate the effect of perineural tramadol as the sole analgesic in two pain models. Male Wistar rats (280-380 g; N = 5/group) were used in these experiments. A neurostimulation-guided sciatic nerve block was performed and 2% lidocaine or tramadol (1.25 and 5 mg) was perineurally injected in two different animal pain models. In the flinching behavior test, the number of flinches was evaluated and in the plantar incision model, mechanical and heat thresholds were measured. Motor effects of lidocaine and tramadol were quantified and a motor block score elaborated. Tramadol, 1.25 mg, completely blocked the first and reduced the second phase of the flinching behavior test. In the plantar incision model, tramadol (1.25 mg) increased both paw withdrawal latency in response to radiant heat (8.3 ± 1.1, 12.7 ± 1.8, 8.4 ± 0.8, and 11.1 ± 3.3 s) and mechanical threshold in response to von Frey filaments (459 ± 82.8, 447.5 ± 91.7, 320.1 ± 120, 126.43 ± 92.8 mN) at 5, 15, 30, and 60 min, respectively. Sham block or contralateral sciatic nerve block did not differ from perineural saline injection throughout the study in either model. The effect of tramadol was not antagonized by intraperitoneal naloxone. High dose tramadol (5 mg) blocked motor function as well as 2% lidocaine. In conclusion, tramadol blocks nociception and motor function in vivo similar to local anesthetics.

Association of rs12255372 in theTCF7L2 gene with type 2 diabetes mellitus: a meta-analysis

Our objective was to evaluate the association of rs12255372 in theTCF7L2 gene with type 2 diabetes mellitus (T2DM) in the world population. We carried out a survey of the literature about the effect of rs12255372 on genetic susceptibility to T2DM by consulting PubMed, the Cochrane Library, and Embase from 2006 to 2012, and then performed a meta-analysis of all the studies in order to evaluate the association between rs12255372 and T2DM. A total of 33 articles including 42 studies (with 34,076 cases and 36,192 controls) were confirmed to be eligible and were included in the final meta-analysis: 6 studies conducted on Europeans, 14 on Caucasians, 17 on Asians, 2 on Africans, and 3 on Americans. Overall, the effect size was as follows: for the variant allele T (OR = 1.387, 95%CI = 1.351-1.424), for the TT genotype (OR = 1.933, 95%CI = 1.815-2.057), for the GT genotype (OR = 1.363, 95%CI = 1.315-1.413), for the dominant model (OR = 1.425, 95%CI = 1.344-1.510), and for the recessive model (OR = 1.659, 95%CI = 1.563-1.761). In summary, by pooling all available qualified data from genetic studies on rs12255372 and T2DM, we have confirmed that rs12255372 is significantly associated with susceptibility to T2DM in the global population.

Determination of pectin methylesterase activity in commercial pectinases and study of the inactivation kinetics through two potentiometric procedures

Pectinases are enzymes that degrade pectic substances and are widely used in juice and fruit beverages to improve the quality of the process. The objective of this study was to determine the optimum pH and temperature of two samples of commercial pectinases and propose an alternative procedure to determine the residual activity comparing the data with those of the traditional procedure. The pectin methylesterase (PME) activity in Pectinex 100 L Plus and Panzyn Clears was determined by potentiometry. The reaction consisted of 5.00 mg.mL-1 apple pectin, 0.100 mol.L-1 NaCl, and 50 µL enzyme to a total volume of 30 mL. The pectin reaction in the presence of PME in all experiments revealed a first order kinetics. The PME in the two enzyme preparations showed higher activity at pH 4.0 to 4.5 and temperature of 45 ºC. From the results of both procedures 16;V NaOH/ 16;t and 16;pH/ 16;t, it was concluded that the inactivation of PME occurred at 75 ºC. The results obtained from the ratio 16;pH/ 16;t showed good correlation with those obtained from the ratio 16;V NaOH/ 16;t. In the reaction accompanied by the ratio 16;pH/ 16;t, the release of H3O+ occurred in the real time reaction.

Mathematical modeling of microbial growth in milk

A mathematical model to predict microbial growth in milk was developed and analyzed. The model consists of a system of two differential equations of first order. The equations are based on physical hypotheses of population growth. The model was applied to five different sets of data of microbial growth in dairy products selected from Combase, which is the most important database in the area with thousands of datasets from around the world, and the results showed a good fit. In addition, the model provides equations for the evaluation of the maximum specific growth rate and the duration of the lag phase which may provide useful information about microbial growth.

Effects of heat treatment and storage temperature on the use of açaí drink by nutraceutical and beverage industries

This study assesses the storage temperature effect on the anthocyanins of pasteurized and unpasteurized açaí pulp. The data was obtained using a pasteurized and lyophilized pulp (PLP) to evaluate the temperature effect (0, 25, and 40 °C). Part of non-pasteurized frozen pulp (NPP) was pasteurized (NPP-P) at 90 °C for 30 seconds; both pulps were stored at 40 °C. The anthocyanin content reduction in the drink was evaluated from the half-life time (t1/2), activation energy (Ea), temperature quotient (Q10), and the reaction rate constant (k). The t1/2 of the PLP anthocyanins stored at 40 °C was 1.8 times less than that stored at 25 °C and 15 times less than that stored at 0 °C; therefore, the higher temperatures decreased the stability of anthocyanins. The pasteurization increased the t1/2 by 6.6 times (10.14 hours for NPP and 67.28 hours for NPP-P). The anthocyanin degradation on NPP-P followed a first order kinetic, while NPP followed a second order kinetic; thus it can be said that the pasteurization process can improve the preservation of anthocyanins in the pulp.