991 resultados para THERMONUCLEAR REACTION-RATES
Resumo:
The effect of the heat flux on the rate of chemical reaction in dilute gases is shown to be important for reactions characterized by high activation energies and in the presence of very large temperature gradients. This effect, obtained from the second-order terms in the distribution function (similar to those obtained in the Burnett approximation to the solution of the Boltzmann equation), is derived on the basis of information theory. It is shown that the analytical results describing the effect are simpler if the kinetic definition for the nonequilibrium temperature is introduced than if the thermodynamic definition is introduced. The numerical results are nearly the same for both definitions
Resumo:
After incidentally learning about a hidden regularity, participants can either continue to solve the task as instructed or, alternatively, apply a shortcut. Past research suggests that the amount of conflict implied by adopting a shortcut seems to bias the decision for vs. against continuing instruction-coherent task processing. We explored whether this decision might transfer from one incidental learning task to the next. Theories that conceptualize strategy change in incidental learning as a learning-plus-decision phenomenon suggest that high demands to adhere to instruction-coherent task processing in Task 1 will impede shortcut usage in Task 2, whereas low control demands will foster it. We sequentially applied two established incidental learning tasks differing in stimuli, responses and hidden regularity (the alphabet verification task followed by the serial reaction task, SRT). While some participants experienced a complete redundancy in the task material of the alphabet verification task (low demands to adhere to instructions), for others the redundancy was only partial. Thus, shortcut application would have led to errors (high demands to follow instructions). The low control demand condition showed the strongest usage of the fixed and repeating sequence of responses in the SRT. The transfer results are in line with the learning-plus-decision view of strategy change in incidental learning, rather than with resource theories of self-control.
Resumo:
It was evaluated the genetic divergence in peach genotypes for brown rot reaction. It was evaluated 26 and 29 peach genotypes in the 2009/2010 and 2010/2011 production cycle, respectively. The experiment was carried out at the Laboratório de Fitossanidade, da UTFPR - Campus Dois Vizinhos. The experimental design was entirely randomized, considering each peach genotype a treatment, and it was use three replication of nine fruits. The treatment control use three replication of three peach. The fruit epidermis were inoculated individually with 0.15 mL of M. fructicola conidial suspension (1.0 x 10(5) spores mL-1). In the control treatment was sprayed with 0.15 mL of distilled water. The fruits were examined 72 and 120 hours after inoculation, and the incidence and severity disease were evaluated. These results allowed realized study for genetic divergence, used as dissimilarity measure the Generalized Mahalanobis distance. Cluster analysis using Tocher´s optimization method and distances in the plan were applied. There was smallest genetic divergence among peach trees evaluated for brown rot, what can difficult to obtain resistance in the genotypes.
Resumo:
Main concepts : The Grades of Recommendation, Assessment, Development, and Evaluation (GRADE) approach defines quality of evidence as confidence in effect estimates; this conceptualization can readily be applied to bodies of evidence estimating the risk of future of events (that is, prognosis) in broadly defined populations In the field of prognosis, a body of observational evidence (including single arms of randomized controlled trials) begins as high quality evidence. The five domains GRADE considers in rating down confidence in estimates of treatment effect-that is, risk of bias, imprecision, inconsistency, indirectness, and publication bias-as well as the GRADE criteria for rating up quality, also apply to estimates of the risk of future of events from a body of prognostic studies Applying these concepts to systematic reviews of prognostic studies provides a ful approach to determine confidence in estimates of overall prognosis in broad populations.
Resumo:
[cat] El propòsit d'aquest article és introduir una mercat de treball no competitiu i atur en el model de creixement amb taxes d'estalvi exògenes que es pot trobar en els llibres de text de creixement (Sala‐i‐Martín, 2000; Barro and Sala‐i‐Martín, 2003; Romer, 2006). Primer, derivem un marc general amb una funció de producció neoclàssica per analitzar la relació entre creixement i ocupació. Utilitzem aquest marc per estudiar les dinàmiques conjuntes del creixement i l'ocupació sota diferents regles de fixació salarial.
Resumo:
[cat] El propòsit d'aquest article és introduir una mercat de treball no competitiu i atur en el model de creixement amb taxes d'estalvi exògenes que es pot trobar en els llibres de text de creixement (Sala‐i‐Martín, 2000; Barro and Sala‐i‐Martín, 2003; Romer, 2006). Primer, derivem un marc general amb una funció de producció neoclàssica per analitzar la relació entre creixement i ocupació. Utilitzem aquest marc per estudiar les dinàmiques conjuntes del creixement i l'ocupació sota diferents regles de fixació salarial.
Resumo:
Työn tavoitteena oli kehittää mallit jäännöshiilen ja kalkkikiven reaktiokinetiikan sekä jäännöshiilen jauhautumisen ennustamiseksi kiertoleijukattilan tulipesässä. Kehitetyt mallit toimivat tulipesämallin osamalleina. Perustuen mallinnettuihin reaktionopeuksiin ja jauhautumiskäyttäytymiseen tulipesämalli ennustaa kalkkikivihiukkasten rikinsidonnan ja jäännöshiilen jakautumisen erikokoisiksi hiukkasiksi tulipesässä ja tuhkissa. Työssä kehitetyt mallit perustuvat olemassa oleviin kalkkikiven ja polttoaineen reaktiivisuustesteihin laboratorio-kokoluokan leijukerrosreaktorissa. Mallit huomioivat myös tulipesän olosuhteet. Menetelmät kelpoistettiin onnistuneesti kaupallisen kokoluokan kiertoleijukattiloista mitattujen ja tulipesämallilla laskettujen taseiden avulla. Mallien kehittämistä tullaan jatkamaan.
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The avidity of the T-cell receptor (TCR) for antigenic peptides presented by the peptide-MHC (pMHC) on cells is a key parameter for cell-mediated immunity. Yet a fundamental feature of most tumor antigen-specific CD8(+) T cells is that this avidity is low. In this study, we addressed the need to identify and select tumor-specific CD8(+) T cells of highest avidity, which are of the greatest interest for adoptive cell therapy in patients with cancer. To identify these rare cells, we developed a peptide-MHC multimer technology, which uses reversible Ni(2+)-nitrilotriacetic acid histidine tags (NTAmers). NTAmers are highly stable but upon imidazole addition, they decay rapidly to pMHC monomers, allowing flow-cytometric-based measurements of monomeric TCR-pMHC dissociation rates of living CD8(+) T cells on a wide avidity spectrum. We documented strong correlations between NTAmer kinetic results and those obtained by surface plasmon resonance. Using NTAmers that were deficient for CD8 binding to pMHC, we found that CD8 itself stabilized the TCR-pMHC complex, prolonging the dissociation half-life several fold. Notably, our NTAmer technology accurately predicted the function of large panels of tumor-specific T cells that were isolated prospectively from patients with cancer. Overall, our results demonstrated that NTAmers are effective tools to isolate rare high-avidity cytotoxic T cells from patients for use in adoptive therapies for cancer treatment.
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A method for the measurement of carbamoyl-phosphate synthetase I activity in animal tissues has been developed using the livers of rats under normal and hyperproteic diets. The method is based on the incorporation of 14C-ammonium bicarbonate to carbamoyl-phosphate in the presence of ATP-Mg and N-acetyl-glutamate. The reaction is stopped by chilling, lowering the pH and adding ethanol. Excess bicarbonate is flushed out under a gentle stream of cold CO2. The only label remaining in the medium was that incorporated into carbamoyl-phosphate, since all 14C-CO2 from bicarbonate was eliminated. The method is rapid and requires only a low pressure supply of CO2 to remove the excess substrate. The reaction is linear up to 10 min using homogenate dilutions of 1:20 to 1:200 (w/v). Rat liver activity was in the range of 89±8 nkat/g. Hyperproteic diet resulted in a significant 1.4-fold increase. The design of the method allows for the processing of multiple samples at the same time, and incubation medium manipulation is unnecessary, since the plastic incubation vial and its contents are finally counted together.
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Työn tarkoituksena oli tutkia lämpötilan, paineen, pH:n ja katalyytin vaikutusta paperitehtaan TMP-konsentroidun prosessiveden märkähapetuksessa. Teoriaosio sisältää katsauksen sellu- ja paperiteollisuuteen, jätevesien käsittelyyn, nanosuodatuksen ja märkähapetusprosessin toimintaperiaatteet ja sovellukset hybriditeknologialle nanosuodatus-märkähapetuksessa. Empiirinen osa koostuu märkähapetuskokeista eri lämpötiloissa, paineissa, pH:ssa ja eri katalyyseillä. Työssä tutkittiin näiden vaikutusta kemialliseen hapenkulutukseen (COD), Biologiseen hapenkulutukseen (BOD), Välittömästi saatavana olevan biologisen hapenkulutukseen (IABOD), ligniiniin, täysin orgaanisen hiileen (TOC) ja rasvaliukoisten uuteaineiden (LWEs) pitoisuuteen. Tuloksina kokeellisesta työstä saatiin korkeimmat COD:n alenemat ja BOD/COD (biohajoavuus) suurimmilla lämpötilaolosuhteilla (COD:n alenema 70 % ja BOD/COD 97 % 200 °C:ssa ja hapen 10 bar osapaineella). Tutkimuksessa, jossa selvitettiin hapen osapaineen vaikutusta saatiin tuloksena, että hapen osapaineen kasvu parantaa orgaanisen kuormituksen poistoa: COD poisto oli olosuhteilla130°C, 5bar 5 %, olosuhteilla 130 °C, 15bar 15 %, olosuhteilla 170 °C, 5bar 20 % ja olosuhteilla 170 °C, 15bar 50 %. Lähes täydellinen LWEs –poisto saavutettiin 150 °C ja 10bar olosuhteilla, vaikka tässä lämpötilassa ei saavutettu korkeata orgaanisen kuormituksen poistoa. Emäksinen pH vaikutti suosivan hapettavia reaktioita, koska korkein COD:n poisto saavutettiin näissä olosuhteilla; kuitenkin alkalisen väliaineen tehokkuudelle löydettiin tärkeä lämpötilariippuvuus.
Resumo:
The computer simulation of reaction dynamics has nowadays reached a remarkable degree of accuracy. Triatomic elementary reactions are rigorously studied with great detail on a straightforward basis using a considerable variety of Quantum Dynamics computational tools available to the scientific community. In our contribution we compare the performance of two quantum scattering codes in the computation of reaction cross sections of a triatomic benchmark reaction such as the gas phase reaction Ne + H2+ %12. NeH++ H. The computational codes are selected as representative of time-dependent (Real Wave Packet [ ]) and time-independent (ABC [ ]) methodologies. The main conclusion to be drawn from our study is that both strategies are, to a great extent, not competing but rather complementary. While time-dependent calculations advantages with respect to the energy range that can be covered in a single simulation, time-independent approaches offer much more detailed information from each single energy calculation. Further details such as the calculation of reactivity at very low collision energies or the computational effort related to account for the Coriolis couplings are analyzed in this paper.
Resumo:
The Annonaceae includes cultivated species of economic interest and represents an important source of information for better understanding the evolution of tropical rainforests. In phylogenetic analyses of DNA sequence data that are used to address evolutionary questions, it is imperative to use appropriate statistical models. Annonaceae are cases in point: Two sister clades, the subfamilies Annonoideae and Malmeoideae, contain the majority of Annonaceae species diversity. The Annonoideae generally show a greater degree of sequence divergence compared to the Malmeoideae, resulting in stark differences in branch lengths in phylogenetic trees. Uncertainty in how to interpret and analyse these differences has led to inconsistent results when estimating the ages of clades in Annonaceae using molecular dating techniques. We ask whether these differences may be attributed to inappropriate modelling assumptions in the phylogenetic analyses. Specifically, we test for (clade-specific) differences in rates of non-synonymous and synonymous substitutions. A high ratio of nonsynonymous to synonymous substitutions may lead to similarity of DNA sequences due to convergence instead of common ancestry, and as a result confound phylogenetic analyses. We use a dataset of three chloroplast genes (rbcL, matK, ndhF) for 129 species representative of the family. We find that differences in branch lengths between major clades are not attributable to different rates of non-synonymous and synonymous substitutions. The differences in evolutionary rate between the major clades of Annonaceae pose a challenge for current molecular dating techniques that should be seen as a warning for the interpretation of such results in other organisms.