ABSTRACT
Nonequilibrium phase transitions can be typified in a similar way to equilibrium systems, for instance, by the use of the order parameter. However, this characterization hides the irreversible character of the dynamics as well as its influence on the phase transition properties. Entropy production has been revealed to be an important concept for filling this gap since it vanishes identically for equilibrium systems and is positive for the nonequilibrium case. Based on distinct and general arguments, the characterization of phase transitions in terms of the entropy production is presented. Analysis for discontinuous and continuous phase transitions has been undertaken by taking regular and complex topologies within the framework of mean-field theory (MFT) and beyond the MFT. A general description of entropy production portraits for Z_{2} ("up-down") symmetry systems under the MFT is presented. Our main result is that a given phase transition, whether continuous or discontinuous has a specific entropy production hallmark. Our predictions are exemplified by an icon system, perhaps the simplest nonequilibrium model presenting an order-disorder phase transition and spontaneous symmetry breaking: the majority vote model. Our work paves the way to a systematic description and classification of nonequilibrium phase transitions through a key indicator of system irreversibility.
ABSTRACT
A digestibility assay was conducted in order to determine the digestibility coefficients (DC) of amino acids of feed ingredients in cecectomized adult roosters. In total 48 cecectomized adult roosters were used to assess the coefficient of digestibility of 7 ingredients: corn, soybean meal, soybean concentrate, corn gluten meal, wheat bran, peanut meal, and feather meal. Each ingredient was replicated six times and a group of 6 rooster was used to measure endogenous amino acid losses. After 48 hours of fasting, the roosters were tube fed 20g of ingredients tested twice during a day. At 12 hour-intervals excreta and endogenous losses were collected and immediately freeze-dried for further chemical analysis. At the end of the assay, excreta were weighed and samples of ingredients, excreta, and endogenous losses were pooled and analysed for dry matter, nitrogen and amino acid content. The coefficients of indispensable amino acids for the most feed ingredients assessed in the current research were similar to published literature like AMINODat®5.0 and the 4th edition of the Brazilian Tables for Poultry and Swine, except feather meal, in which only digestible Trp and Thr content were similar to literature. Particularly, the coefficients for some amino acids like Arg and Gly exhibited large discrepancies from literature in almost all the feed ingredients assessed herein. In general, using cecectomized adult roosters proved to be a reliable technique to assess the digestibility of feed ingredients used in poultry diets.(AU)
Subject(s)
Animals , Chickens/metabolism , Chickens/physiology , Amino AcidsABSTRACT
A digestibility assay was conducted in order to determine the digestibility coefficients (DC) of amino acids of feed ingredients in cecectomized adult roosters. In total 48 cecectomized adult roosters were used to assess the coefficient of digestibility of 7 ingredients: corn, soybean meal, soybean concentrate, corn gluten meal, wheat bran, peanut meal, and feather meal. Each ingredient was replicated six times and a group of 6 rooster was used to measure endogenous amino acid losses. After 48 hours of fasting, the roosters were tube fed 20g of ingredients tested twice during a day. At 12 hour-intervals excreta and endogenous losses were collected and immediately freeze-dried for further chemical analysis. At the end of the assay, excreta were weighed and samples of ingredients, excreta, and endogenous losses were pooled and analysed for dry matter, nitrogen and amino acid content. The coefficients of indispensable amino acids for the most feed ingredients assessed in the current research were similar to published literature like AMINODat®5.0 and the 4th edition of the Brazilian Tables for Poultry and Swine, except feather meal, in which only digestible Trp and Thr content were similar to literature. Particularly, the coefficients for some amino acids like Arg and Gly exhibited large discrepancies from literature in almost all the feed ingredients assessed herein. In general, using cecectomized adult roosters proved to be a reliable technique to assess the digestibility of feed ingredients used in poultry diets.
Subject(s)
Animals , Amino Acids , Chickens/physiology , Chickens/metabolismABSTRACT
Para evitar maiores perdas de biodiversidade, é necessário direcionar esforços para diversas áreas da conservação, como a reprodução em cativeiro. O maior obstáculo, porém, nessa abordagem, é a condição de estresse crônico que diversos animais desenvolvem em cativeiro por deficiências relacionadas ao manejo, às condições de recinto, à nutrição e ao acompanhamento clínico. Melhores resultados na reprodução de felídeos em cativeiro certamente são derivados de baixos índices de estresse crônico no plantel. Objetivou-se com o presente texto revisar mecanismos causadores de estresse crônico e explorar suas possíveis origens bem como, sugerir alterações de manejo para controlá-lo.(AU)
Efforts in different areas of conservation, like captive breeding, are extremely important to avoid further loss of biodiversity. The biggest obstacle in this approach however, is the condition of chronic stress that several animals develop in captivity because of failures related to the management, enclosure conditions, nutrition and health. Good results in the reproduction of felids in captivity are certainly derived from low levels of chronic stress. The purpose in this paper is to review the chronic stress causing mechanisms, besides exploring its possible origins and suggest changes in management in order to control it.(AU)
Subject(s)
Animals , Pregnancy, Animal/physiology , Felidae/embryology , Biodiversity , Stress, Physiological , Physiology , Luteinizing Hormone/chemistry , Follicle Stimulating HormoneABSTRACT
Para evitar maiores perdas de biodiversidade, é necessário direcionar esforços para diversas áreas da conservação, como a reprodução em cativeiro. O maior obstáculo, porém, nessa abordagem, é a condição de estresse crônico que diversos animais desenvolvem em cativeiro por deficiências relacionadas ao manejo, às condições de recinto, à nutrição e ao acompanhamento clínico. Melhores resultados na reprodução de felídeos em cativeiro certamente são derivados de baixos índices de estresse crônico no plantel. Objetivou-se com o presente texto revisar mecanismos causadores de estresse crônico e explorar suas possíveis origens bem como, sugerir alterações de manejo para controlá-lo.
Efforts in different areas of conservation, like captive breeding, are extremely important to avoid further loss of biodiversity. The biggest obstacle in this approach however, is the condition of chronic stress that several animals develop in captivity because of failures related to the management, enclosure conditions, nutrition and health. Good results in the reproduction of felids in captivity are certainly derived from low levels of chronic stress. The purpose in this paper is to review the chronic stress causing mechanisms, besides exploring its possible origins and suggest changes in management in order to control it.
Subject(s)
Animals , Felidae/embryology , Pregnancy, Animal/physiology , Biodiversity , Stress, Physiological , Physiology , Follicle Stimulating Hormone , Luteinizing Hormone/chemistryABSTRACT
A reprodução em cativeiro é uma das ferramentas para a conservação ex situ de felídeos selvagens que, em sua maioria, estão ameaçados de extinção. Esforços em diversas frentes estão sendo feitos para evitar o desaparecimento desses carnívoros em todo o mundo. Para se obter sucesso na conservação dessas espécies, no entanto, é necessário ampliar o conhecimento sobre os aspectos da reprodução delas, assim como aprimorar as técnicas empregadas em sua reprodução assistida de modo a transpor as dificuldades e limitações de cada uma dessas técnicas. O objetivo desta revisão é compilar as informações disponíveis sobre os aspectos reprodutivos da família Felidae e as biotécnicas reprodutivas aplicáveis a essas espécies. (AU)
Reproduction in captivity has been presented as a tool to ex situ conservation of wild felids that are, mostly, threatened with extinction. Efforts in several fronts are being made to avoid disappearance of these carnivores around the world. However, to achieve success in the conservation of these species it is necessary to extend our knowledge about the aspects of felid reproduction, as well as improve the techniques employed in assisted reproduction to overcome the difficulties and limitations of these techniques. This review aimed to compile the information available on the reproductive aspects of the family Felidae and reproductive biotechnology for these species.(AU)
Subject(s)
Animals , Male , Female , Reproductive Techniques , Reproductive Techniques/veterinary , Felidae/embryology , Immunodeficiency Virus, Feline , Fertilization in Vitro/veterinary , Insemination, Artificial , Endangered Species , Ovulation , GonadotropinsABSTRACT
A reprodução em cativeiro é uma das ferramentas para a conservação ex situ de felídeos selvagens que, em sua maioria, estão ameaçados de extinção. Esforços em diversas frentes estão sendo feitos para evitar o desaparecimento desses carnívoros em todo o mundo. Para se obter sucesso na conservação dessas espécies, no entanto, é necessário ampliar o conhecimento sobre os aspectos da reprodução delas, assim como aprimorar as técnicas empregadas em sua reprodução assistida de modo a transpor as dificuldades e limitações de cada uma dessas técnicas. O objetivo desta revisão é compilar as informações disponíveis sobre os aspectos reprodutivos da família Felidae e as biotécnicas reprodutivas aplicáveis a essas espécies.
Reproduction in captivity has been presented as a tool to ex situ conservation of wild felids that are, mostly, threatened with extinction. Efforts in several fronts are being made to avoid disappearance of these carnivores around the world. However, to achieve success in the conservation of these species it is necessary to extend our knowledge about the aspects of felid reproduction, as well as improve the techniques employed in assisted reproduction to overcome the difficulties and limitations of these techniques. This review aimed to compile the information available on the reproductive aspects of the family Felidae and reproductive biotechnology for these species.
Subject(s)
Male , Female , Animals , Felidae/embryology , Reproductive Techniques , Reproductive Techniques/veterinary , Endangered Species , Fertilization in Vitro/veterinary , Gonadotropins , Insemination, Artificial , Ovulation , Immunodeficiency Virus, FelineABSTRACT
A generalized version of the nonequilibrium linear Glauber model with q states in d dimensions is introduced and analyzed. The model is fully symmetric, its dynamics being invariant under all permutations of the q states. Exact expressions for the two-time autocorrelation and response functions on a d-dimensional lattice are obtained. In the stationary regime, the fluctuation-dissipation theorem holds, while in the transient the aging is observed with the fluctuation-dissipation ratio leading to the value predicted for the linear Glauber model.
ABSTRACT
In the present work a comparative quantitative evaluation of the differential effects of neuromuscular blockers on twitches and tetani was performed, encompassing: atracurium, cisatracurium, mivacurium, pancuronium, rocuronium and vecuronium. The sciatic nerve-extensor digitorum longus muscle of the rat was used, in vitro. Twitches were evoked at 0.1 Hz and tetani at 50 Hz. The differential effects of the studied compounds on twitches and tetani were statistically compared using simultaneous confidence intervals for the ratios between mean IC(50) for the block of twitches and mean IC(50) for the block of tetani. The results of ratios of mean IC(50) together with their corresponding 95% simultaneous confidence intervals were: vecuronium: 2.5 (1.8-3.5); mivacurium: 3.8 (3.0-4.9); pancuronium: 3.9 (2.0-7.6); rocuronium: 6.1 (3.8-9.9); atracurium: 9.0 (6.4-12.6); cisatracurium: 13.1 (6.0-28.4). Using the criteria that neuromuscular blockers displaying disjunct confidence intervals for the ratios of mean IC(50) differ statistically with regard to differential effects on twitches and tetani, significant differences in ratios of IC(50) were detected in the following cases: vecuronium vs. rocuronium, vs. atracurium and vs. cisatracurium and mivacurium vs: cisatracurium and vs. atracurium. The results show that the magnitude of the differential effects of neuromuscular blockers on twitches and tetani, as evaluated in the present work in the form of ratios of mean IC(50), does not depend on the chemical structure (comparing steroidal and isoquinolinic compounds), but seems to depend on differential pre- and post-synaptic effects of the compounds. It is also suggested that the greater the ability of a compound to block twitches and tetani in a differential manner, the safer is the compound from the clinical anesthesiology viewpoint.
Subject(s)
Muscle, Skeletal/drug effects , Neuromuscular Blocking Agents/therapeutic use , Tetany/prevention & control , Animals , Confidence Intervals , Female , In Vitro Techniques , Male , Muscle Contraction/drug effects , Muscle Contraction/physiology , Muscle, Skeletal/physiology , Neuromuscular Blocking Agents/pharmacology , Neuromuscular Junction/drug effects , Neuromuscular Junction/physiology , Rats , Rats, Wistar , Spasm/physiopathology , Spasm/prevention & control , Tetany/physiopathologyABSTRACT
We study a stochastic lattice model describing the dynamics of coexistence of two interacting biological species. The model comprehends the local processes of birth, death, and diffusion of individuals of each species and is grounded on interaction of the predator-prey type. The species coexistence can be of two types: With self-sustained coupled time oscillations of population densities and without oscillations. We perform numerical simulations of the model on a square lattice and analyze the temporal behavior of each species by computing the time correlation functions as well as the spectral densities. This analysis provides an appropriate characterization of the different types of coexistence. It is also used to examine linked population cycles in nature and in experiment.
Subject(s)
Biophysics/methods , Algorithms , Animals , Computer Simulation , Diffusion , Food Chain , Models, Biological , Models, Statistical , Models, Theoretical , Oscillometry , Population Dynamics , Predatory Behavior , Probability , Stochastic Processes , Time FactorsABSTRACT
In the present work a comparative quantitative evaluation of the differential effects of neuromuscular blockers on twitches and tetani was performed, encompassing atracurium, cisatracurium, mivacurium, pancuronium, rocuronium and vecuronium. The sciatic nerve-extensor digitorum longus muscle of the rat was used, in vitro. Twitches were evoked at 0.1 Hz and tetani at 50 Hz. The differential effects of the studied compounds on twitches and tetani were statistically compared using simultaneous confidence intervals for the ratios between mean IC(50) for the block of twitches and mean IC(50) for the block of tetani. The results of ratios of mean IC(50) together with their corresponding 95% simultaneous confidence intervals were vecuronium 2.5 (1.8-3.5); mivacurium 3.8 (3.0-4.9); pancuronium 3.9 (2.0-7.6); rocuronium 6.1 (3.8-9.9); atracurium 9.0 (6.4-12.6); cisatracurium 13.1 (6.0-28.4). Using the criteria that neuromuscular blockers displaying disjunct confidence intervals for the ratios of mean IC(50) differ statistically with regard to differential effects on twitches and tetani, significant differences in ratios of IC(50) were detected in the following cases vecuronium vs. rocuronium, vs. atracurium and vs. cisatracurium and mivacurium vs cisatracurium and vs. atracurium. The results show that the magnitude of the differential effects of neuromuscular blockers on twitches and tetani, as evaluated in the present work in the form of ratios of mean IC(50), does not depend on the chemical structure (comparing steroidal and isoquinolinic compounds), but seems to depend on differential pre- and post-synaptic effects of the compounds. It is also suggested that the greater the ability of a compound to block twitches and tetani in a differential manner, the safer is the compound from the clinical anesthesiology viewpoint.
Subject(s)
Animals , Male , Female , Rats , Spasm , Tetany/prevention & control , In Vitro Techniques , Confidence Intervals , Rats, Wistar , Muscle, Skeletal , Muscle Contraction , Neuromuscular Blocking Agents , Neuromuscular JunctionABSTRACT
By using the transfer matrix approach, we investigate the asymptotic behavior of the entropy of flexible chains with M monomers each placed on strips with periodic boundary conditions (cylinders). In the limit of high density of monomers, we study the behavior of the entropy as a function of the density of monomers and the width of the strip, inspired by recent analytical studies of this problem for the particular case of dimers (M=2). We obtain the entropy in the asymptotic regime of high densities for chains with M=2,...,9 monomers, as well as for the special case of polymers, where M-->infinity, and find that the results show a regular behavior similar to the one found analytically for dimers. We also verify that in the low-density limit the mean-field expression for the entropy is followed by the results from our transfer matrix calculations.
ABSTRACT
The aim of the present study was to determine fluoride intake by children at risk of dental fluorosis according to the type of dentifrice used. Forty-two volunteers aged between 20 and 30 months, from 2 kindergartens, were supervised while brushing their teeth with regular dentifrices (nominally 1,500 ppm F) and dentifrices flavoured for children (nominally 1,100 ppm F), brushing 3 times with each type in random order to minimize bias. The amount of fluoride ingested was determined by subtracting the weight of dentifrice recovered from the weight used and calculating the mean of the 3 brushings. Fluoride was analyzed with specific electrodes. Parents were asked how often the children brushed their teeth and the daily tooth brushing frequency was used to calculate the daily fluoride intake. The average fluoride intake using regular dentifrices and those flavoured for children was 0.567 +/- 0.300 and 0.630 +/- 0.320 mg F/day, respectively, corresponding to doses of 0.046 +/- 0.023 and 0.051 +/- 0.026 mg F/kg/day (p > 0.05). Fluoride intake was slightly higher with the use of dentifrices flavoured for children. Moreover, the dose to which children were exposed with either type of dentifrice was very close to that which is considered the limit (0.05-0.07 mg F/kg/day).
Subject(s)
Cariostatic Agents/administration & dosage , Dentifrices/administration & dosage , Fluorides/administration & dosage , Fluorosis, Dental , Toothbrushing , Cariostatic Agents/adverse effects , Cariostatic Agents/analysis , Child, Preschool , Dentifrices/analysis , Dentifrices/chemistry , Epidemiologic Methods , Female , Flavoring Agents/administration & dosage , Fluorides/adverse effects , Fluorides/analysis , Humans , Infant , MaleABSTRACT
We obtain exact expressions for the two-time autocorrelation and response functions of the -dimensional linear Glauber model. Although this linear model does not obey detailed balance in dimensions d > or = 2, we show that the usual form of the fluctuation-dissipation ratio still holds in the stationary regime. In the transient regime, we show the occurrence of aging, with a special limit of the fluctuation-dissipation ratio, x(infinity) = 1/2, for a quench at the critical point.
ABSTRACT
Using the transfer matrix technique, finite-size scaling, phenomenological renormalization group, and conformal invariance ideas, the thermodynamic behavior of a polymer with interacting bonds on a square lattice has been studied. In this model, one monomer that belongs to the polymer has an activity x=e(beta(mu)), while the interactions between bonds of the polymer that are located on opposite edges of elementary squares of the lattice have a statistical weight y=e(-beta(epsilon)), where epsilon is the interaction energy. Next, the phase diagram of the model in the (x,y) plane was found, which shows three phases, two of them being polymerized. Furthermore, the densities of occupied sites and of bond interactions in each phase were calculated, in order to determine the nature of the transitions between the phases. The results obtained are consistent with a second-order transition line between the nonpolymerized and the regular polymerized phase and a first-order transition between the nonpolymerized and the dense polymerized phase. The boundary between both polymerized phases may be of first or second order, and thus evidence for a tricritical point is found.
ABSTRACT
We introduce and analyze numerically a nonequilibrium model with a conserved dynamics which is a realization of the contact process in an ensemble of constant particle number. The model possesses just one process in which particles jump around landing only on empty sites next to an existing particle. Particles are not allowed to land on a vacant site surrounded by empty sites. In contrast with the ordinary contact process, the present model does not have an absorbing state. In spite of lacking an absorbing state, the model displays properties that, in the thermodynamic limit, are identical to those of the ordinary contact process.
ABSTRACT
Pro-inflammatory cytokines are believed to play an important role in the pathogenesis of dengue infection. This study reports cytokine levels in a total of 54 patients examined in Recife, State of Pernambuco, Brazil. Five out of eight patients who had hemorrhagic manifestations presented tumor necrosis factor-alpha (TNF-alpha) levels in sera which were statistically higher than those recorded for controls. In contrast, only one out of 16 patients with mild manifestations had elevated TNF-alpha levels. The levels of interleukin-6 (IL), IL-1beta tested in 24 samples and IL-12 in 30 samples were not significantly increased. Interferon-g was present in 10 out of 30 patients with dengue. The data support the concept that the increased level of TNF-alpha is related to the severity of the disease. Soluble TNF receptor p75 was found in most patients but it is unlikely to be related to severity since it was found with an equivalent frequency and levels in 15 patients with dengue fever and another 15 with dengue hemorrhagic fever.
Subject(s)
Antigens, CD/blood , Cytokines/blood , Dengue/blood , Receptors, Tumor Necrosis Factor/blood , Adult , Antigens, CD/isolation & purification , Brazil , Child , Cytokines/isolation & purification , Dengue/immunology , Humans , Interferon-alpha/blood , Interferon-alpha/isolation & purification , Receptors, Tumor Necrosis Factor/isolation & purification , Receptors, Tumor Necrosis Factor, Type II , Severe Dengue/blood , Severe Dengue/immunology , Severity of Illness Index , Tumor Necrosis Factor-alpha/isolation & purificationABSTRACT
We study the evolution of interacting individuals located on the sites of a regular lattice. The individuals play a two action game in which the players either cooperate or defect with respect to a certain issue. The main rule of the game is that a player does not change his action when he and his opponent have held the same action in the previous round. Numerical simulations performed on a square lattice show a stationary state in which the lattice has a finite number of cooperators and defectors and two frozen states, one full of cooperators and the other full of defectors.
ABSTRACT
We calculate exactly the time dependent density profile of a one-dimensional stochastic reaction-diffusion process of hard-core particles subjected to the reactions AA <--> OO and AO <--> OA. The solution is based on the fundamental property that the evolution operator, defined over an appropriate vector space, transforms vectors with n kinks into vectors with n or n+2 kinks, only. In this space, a basis vector is represented by a string of plus and minus signs and a kink is defined as a pair of opposite signs. The exact time dependent profiles are calculated for the cases of uncorrelated initial states that are translational invariant as well as initial states that are inhomogeneous in space.
ABSTRACT
The cellular mechanisms underlying the effects of vecuronium on the tetanic contraction were studied in vitro with a combination of myographic and electrophysiologic techniques. We used the isolated sciatic nerve extensor digitorum longus muscle preparation of the rat. Indirect twitches were evoked at 0.1 Hz pulses and tetani at 50 Hz pulses. Trains of end-plate potentials were generated at 50 Hz. The electrophysiological variables used in the analysis of the end-plate potentials were: amplitude, tetanic run-down, quantal size and quantal content. The myographic study demonstrated that vecuronium at 0.4 microM caused tetanic fade, but left the twitch unaffected. Regarding electrophysiology, vecuronium (0.4 microM) decreased the amplitude of end-plate potentials and increased their tetanic run-down. These changes were due to significant reductions in both the quantal content of the end-plate potentials and the quantal size. It is concluded that vecuronium has both pre- and postsynaptic effects at the neuromuscular junction, and that it induces fade of the tetanic contraction via a summation of these effects.