Efectos de los factores dietéticos sobre la conducta agresiva y otras patologías del comportamiento del perro

Studies show that feeding patterns, environmental conditions, and pet management mainly affect animal health, behavior and welfare. However, little epidemiologic data exist about pet dog feeding habits and management and canine behavior, especially aggression. Moreover, it is well known that serotonin is involved in aggression: a diet low in tryptophan (serotonin precursor) with high levels of neutral amino-acids could decrease the central levels of serotonin and increase the expression of aggression and impulsiveness in several domestic animals. oreover, brain levels of serotonin in humans and other species can be increased by physical activity. In this study we alysed the effects of diet management, supplementation and regular physical activity on oncentration of serotonin in a population of non aggressive dogs. The general aim of the study is to determine the effect of environmental factors on the dogs’ feeding habits as well as the relationship between the type of food provided and management and behavioral problems in dogs. The specific objectives were: characterization and comparison of different physiological and blood parameters between dogs with and without behavior pathologies. Observation of the impact of the diet and managment factors (exercise, education) on those parameters and on dog’s behavior, with particular attention to aggression. This study is divided into three phases, according with the objectives. Firstly, characterization of the dogs’ characteristics and serics profiles on the basis of the blood tests. Comparison between the values noticed on animals without any behavior pathology and animals with behavior disorder to point out the difference between the biochemical parameters of the two groups. Secondly, the purpose of the second phase is to verify whether a type of food is able to affect the biochemical paramenters of a population of non-aggressive dogs. Thirdly, the goal is to evaluate the effects of different diet factors, management and physical exercise on the canine aggression.

Spectrum of gluten sensitive enteropathy in first degree relatives of patients with coeliac disease: clinical relevance of lymphocytic enteritis.

Background: Limited data on a short series of patients suggest that lymphocytic enteritis (classically considered as latent coeliac disease) may produce symptoms of malabsorption, although the true prevalence of this situation is unknown. Serological markers of coeliac disease are of little diagnostic value in identifying these patients. Aims: To evaluate the usefulness of human leucocyte antigen-DQ2 genotyping followed by duodenal biopsy for the detection of gluten-sensitive enteropathy in first-degree relatives of patients with coeliac disease and to assess the clinical relevance of lymphocytic enteritis diagnosed with this screening strategy. Patients and methods: 221 first-degree relatives of 82 DQ2+ patients with coeliac disease were consecutively included. Duodenal biopsy (for histological examination and tissue transglutaminase antibody assay in culture supernatant) was carried out on all DQ2+ relatives. Clinical features, biochemical parameters and bone mineral density were recorded. Results: 130 relatives (58.8%) were DQ2+, showing the following histological stages: 64 (49.2%) Marsh 0; 32 (24.6%) Marsh I; 1 (0.8%) Marsh II; 13 (10.0%) Marsh III; 15.4% refused the biopsy. 49 relatives showed gluten sensitive enteropathy, 46 with histological abnormalities and 3 with Marsh 0 but positive tissue transglutaminase antibody in culture supernatant. Only 17 of 221 relatives had positive serological markers. Differences in the diagnostic yield between the proposed strategy and serology were significant (22.2% v 7.2%, p<0.001). Relatives with Marsh I and Marsh II¿III were more often symptomatic (56.3% and 53.8%, respectively) than relatives with normal mucosa (21.1%; p=0.002). Marsh I relatives had more severe abdominal pain (p=0.006), severe distension (p=0.047) and anaemia (p=0.038) than those with Marsh 0. The prevalence of abnormal bone mineral density was similar in relatives with Marsh I (37%) and Marsh III (44.4%). Conclusions: The high number of symptomatic patients with lymphocytic enteritis (Marsh I) supports the need for a strategy based on human leucocyte antigen-DQ2 genotyping followed by duodenal biopsy in relatives of patients with coeliac disease and modifies the current concept that villous atrophy is required to prescribe a gluten-free diet.

Artificial diets for the production of natural enemies (predators and parasitoids) of greenhouse pest insects

The aim of this contract was to finalise in vitro rearing on artificial diets of entomophagous insects useful to control insect pests mainly in greenhouses through an analytical and rational approach. The work focuses on the development and optimisation of artificial diets for one coccinellid (Harmonia axyridis), two heteropteran predators (Orius laevigatus, Dicyphus tamaninii), and a braconid parasitoid of aphids (Aphidius ervi). The definition of the artificial diets was based on biochemical analyses of their natural food (aphids) or substitution food for the predators (Ephestia kuehniella eggs). Reliable quality control parameters of the entomophages produced were used in order to adjust dietary composition and formulation of the different diets tested.

Estudi de l'organogènesi del sistema reproductor de la cabra de mar (Maja brachydactyla) i efecte dels factors ambientals sobre la reproducció en captivitat

Diferents aspectes de la reproducció de la cabra de mar Maja brachydactyla s’han estudiat amb l’objectiu d’obtenir coneixements bàsics i aplicats al cultiu en captivitat d’aquesta espècie de gran interès comercial i aqüícola. L’anatomia interna de l’aparell reproductor masculí, el procés d’espermatogènesi, amb especial èmfasi amb la formació de l’acrosoma, i l’estructura i organització l’espermatozoide s’han descrit amb tècniques microscòpiques avançades. El desenvolupament de les gònades durant els primeres fases del desenvolupament post- embrionari (fases larvàries i primer cranc juvenil) han estat descrites mitjançant la quantificació de l’expressió del gen vasa, el qual és expressat específicament per les cèl•lules de la línia germinal. Aquests coneixements són bàsics per a la comprensió del paper dels mascles en la la reproducció i la seva aplicació posterior en condicions de captivitat. La reproducció en captivitat s’ha estudiat amb una sèrie d’experiments amb l’objectiu de determinar la quantitat, pes sec i composició bioquímica proximal de les larves acabades d’eclosionar en condicions de captivitat i l’efecte de les condicions ambientals, com ara el fotoperíode i la salinitat, sobre aquests paràmetres. Aquests experiments demostren què es poden obtenir larves de la cabra de mar en condicions de captivitat què podrien ser utilitzades per a la producció i l’efecte sobre la reproducció del fotoperíode i salinitat.

Annual variation in the biochemical composition of newly hatched larvae of Maja brachydactyla in captivity

Quality of newly hatched larvae (NHL) of Maja brachydactyla in captivity has been characterized throughout the year to evaluate their availability for mass production. Spawning took place every month and NHL were collected and analyzed to estimate individual dry weight (DW) and proximate biochemical composition (protein, carbohydrate and lipids). Lipid class, fatty acid composition, amino acid profile, mineral and vitamins A, E and C contents were analyzed seasonally. NHL obtained throughout the year are a potential source for aquaculture purposes, since the increment in the relative protein and lipid (especially phospholipids and n-3 PUFA) content might compensate the decrease in DW of larvae hatched from broodstock kept during one year in captivity. However, the decrease in vitamins A and E as well as in certain essential amino acids (Lys, Val, and His) and trace elements (Cu and Fe) of NHL at the end of the year might be indicative of a nutritional deficiency in broodstock diets.

Inference of distributional parameters from compositional samples containing nondetects

Low concentrations of elements in geochemical analyses have the peculiarity of beingcompositional data and, for a given level of significance, are likely to be beyond thecapabilities of laboratories to distinguish between minute concentrations and completeabsence, thus preventing laboratories from reporting extremely low concentrations of theanalyte. Instead, what is reported is the detection limit, which is the minimumconcentration that conclusively differentiates between presence and absence of theelement. A spatially distributed exhaustive sample is employed in this study to generateunbiased sub-samples, which are further censored to observe the effect that differentdetection limits and sample sizes have on the inference of population distributionsstarting from geochemical analyses having specimens below detection limit (nondetects).The isometric logratio transformation is used to convert the compositional data in thesimplex to samples in real space, thus allowing the practitioner to properly borrow fromthe large source of statistical techniques valid only in real space. The bootstrap method isused to numerically investigate the reliability of inferring several distributionalparameters employing different forms of imputation for the censored data. The casestudy illustrates that, in general, best results are obtained when imputations are madeusing the distribution best fitting the readings above detection limit and exposes theproblems of other more widely used practices. When the sample is spatially correlated, itis necessary to combine the bootstrap with stochastic simulation

Identificació i caracterització funcional dels complexes proteics dels receptors BRL1 i BRL3 en el teixit vascular d’Arabidopsis Thaliana

Els esteroids juguen papers clau en el creixement I el desenvolupament d’eucariotes multicel•lulars. En plantes, aquestes hormones, anomenades Brassinosteroides (BRs), estan involucrades en una gran varietat de processos biològics essencials per a les plantes. S’han descrit anteriorment dos receptors de BRs del tipus Leucine Rich Repeat Receptor Like Kinase LRR-RLK, BRASSINOSTEROID RECEPTOR LIKE 1 i 3 (BRL1 i BRL3 respectivalemt) que són homòlegs al receptor principal BRI1 i són necessaris pel desenvolupament vascular. Tot i que els principals components de la senyal ja han estat identificats pel seu homòleg més pròxim, el receptor BRI1, els complexes de BRL1 i BRL3 juntament amb els candidats co-receptors així com els components de la ruta de senyalització encara no han sigut identificats. Per tal d’entendre millor la funció molecular d’aquests receptors de BRs en la planta aquesta tesis doctoral planteja dues aproximacions: com a primera aproximació, vaig realitzar un estudi fenotípic del desenvolupament del teixit vascular a la planta model Arabidopsis thaliana (Arabidopsis). Disposant d'una amplia bateria de mutants de síntesis de la hormona i senyalització del receptor BRI1, vam analitzar quantitativament el seu patró vascular a la tija d'Arabidopsis. Vam establir els paràmetres en les plantes silvestres [Col-0 wild type, (WT)] i els vam analitzar a tots i cadascun dels mutants. Això conjuntament amb una col•laboració amb la Dr. Marta Ibañes, física de la Universitat de Barcelona que va construir un model matemàtic per simular la formació del patró vascular ens va permetre el•laborar una hipòtesis que vam demostrar experimentalment i va ser publicada a la revista PNAS. Posteriorment vam observar que les plantes knock-out d'aquests dos receptors BRL1 y BRL3 a diferència de BRI1, no tenien cap fenotip obvi en el teixit vascular de la planta adulta. Així, a continuació, per entendre quina necessitat té la planta de disposar de tres receptors tant altament homòlegs que poden percebre la mateixa hormona, vam utilitzar una aproximació bioquímica en col•laboració amb el Prof. de Vries de la Universitat de Wageningen (Holanda) per tal de purificar els complexes dels receptors in vivo i els seus interactors. Això ens ha permès entendre millor el paper funcional d'aquests receptors en la planta. Els resultats d’aquests experiments estan resumits en un article en preparació que aviat estarà en revisió.

Simulation methods with extended stability for stiff biochemical kinetics

Background: With increasing computer power, simulating the dynamics of complex systems in chemistry and biology is becoming increasingly routine. The modelling of individual reactions in (bio)chemical systems involves a large number of random events that can be simulated by the stochastic simulation algorithm (SSA). The key quantity is the step size, or waiting time, τ, whose value inversely depends on the size of the propensities of the different channel reactions and which needs to be re-evaluated after every firing event. Such a discrete event simulation may be extremely expensive, in particular for stiff systems where τ can be very short due to the fast kinetics of some of the channel reactions. Several alternative methods have been put forward to increase the integration step size. The so-called τ-leap approach takes a larger step size by allowing all the reactions to fire, from a Poisson or Binomial distribution, within that step. Although the expected value for the different species in the reactive system is maintained with respect to more precise methods, the variance at steady state can suffer from large errors as τ grows. Results: In this paper we extend Poisson τ-leap methods to a general class of Runge-Kutta (RK) τ-leap methods. We show that with the proper selection of the coefficients, the variance of the extended τ-leap can be well-behaved, leading to significantly larger step sizes.Conclusions: The benefit of adapting the extended method to the use of RK frameworks is clear in terms of speed of calculation, as the number of evaluations of the Poisson distribution is still one set per time step, as in the original τ-leap method. The approach paves the way to explore new multiscale methods to simulate (bio)chemical systems.

Stable complexes involving acetylcholinesterase and amyloid-ß-peptide change the biochemical properties of the enzyme and increase the neurotoxicity of Alzheimer's fibrils

Brain acetylcholinesterase (AChE) forms stable complexes with amyloid-beta peptide (Abeta) during its assembly into filaments, in agreement with its colocalization with the Abeta deposits of Alzheimer's brain. The association of the enzyme with nascent Abeta aggregates occurs as early as after 30 min of incubation. Analysis of the catalytic activity of the AChE incorporated into these complexes shows an anomalous behavior reminiscent of the AChE associated with senile plaques, which includes a resistance to low pH, high substrate concentrations, and lower sensitivity to AChE inhibitors. Furthermore, the toxicity of the AChE-amyloid complexes is higher than that of the Abeta aggregates alone. Thus, in addition to its possible role as a heterogeneous nucleator during amyloid formation, AChE, by forming such stable complexes, may increase the neurotoxicity of Abeta fibrils and thus may determine the selective neuronal loss observed in Alzheimer's brain.

Variable Kernel estimates: On the impossibility of tuning the parameters

For the standard kernel density estimate, it is known that one can tune the bandwidth such that the expected L1 error is within a constant factor of the optimal L1 error (obtained when one is allowed to choose the bandwidth with knowledge of the density). In this paper, we pose the same problem for variable bandwidth kernel estimates where the bandwidths are allowed to depend upon the location. We show in particular that for positive kernels on the real line, for any data-based bandwidth, there exists a densityfor which the ratio of expected L1 error over optimal L1 error tends to infinity. Thus, the problem of tuning the variable bandwidth in an optimal manner is ``too hard''. Moreover, from the class of counterexamples exhibited in the paper, it appears thatplacing conditions on the densities (monotonicity, convexity, smoothness) does not help.

On the performance of small-area estimators: Fixed vs. random area parameters

Most methods for small-area estimation are based on composite estimators derived from design- or model-based methods. A composite estimator is a linear combination of a direct and an indirect estimator with weights that usually depend on unknown parameters which need to be estimated. Although model-based small-area estimators are usually based on random-effects models, the assumption of fixed effects is at face value more appropriate.Model-based estimators are justified by the assumption of random (interchangeable) area effects; in practice, however, areas are not interchangeable. In the present paper we empirically assess the quality of several small-area estimators in the setting in which the area effects are treated as fixed. We consider two settings: one that draws samples from a theoretical population, and another that draws samples from an empirical population of a labor force register maintained by the National Institute of Social Security (NISS) of Catalonia. We distinguish two types of composite estimators: a) those that use weights that involve area specific estimates of bias and variance; and, b) those that use weights that involve a common variance and a common squared bias estimate for all the areas. We assess their precision and discuss alternatives to optimizing composite estimation in applications.

A finite-population revenue management model and a risk-ratio procedure for the joint estimation of population size and parameters

Many dynamic revenue management models divide the sale period into a finite number of periods T and assume, invoking a fine-enough grid of time, that each period sees at most one booking request. These Poisson-type assumptions restrict the variability of the demand in the model, but researchers and practitioners were willing to overlook this for the benefit of tractability of the models. In this paper, we criticize this model from another angle. Estimating the discrete finite-period model poses problems of indeterminacy and non-robustness: Arbitrarily fixing T leads to arbitrary control values and on the other hand estimating T from data adds an additional layer of indeterminacy. To counter this, we first propose an alternate finite-population model that avoids this problem of fixing T and allows a wider range of demand distributions, while retaining the useful marginal-value properties of the finite-period model. The finite-population model still requires jointly estimating market size and the parameters of the customer purchase model without observing no-purchases. Estimation of market-size when no-purchases are unobservable has rarely been attempted in the marketing or revenue management literature. Indeed, we point out that it is akin to the classical statistical problem of estimating the parameters of a binomial distribution with unknown population size and success probability, and hence likely to be challenging. However, when the purchase probabilities are given by a functional form such as a multinomial-logit model, we propose an estimation heuristic that exploits the specification of the functional form, the variety of the offer sets in a typical RM setting, and qualitative knowledge of arrival rates. Finally we perform simulations to show that the estimator is very promising in obtaining unbiased estimates of population size and the model parameters.

A type stars - physical parameters from UVBY and H-beta photometry

uvby H-beta photometry has been obtained for a sample of 93 selected main sequence A stars. The purpose was to determine accurate effective temperatures, surface gravities, and absolute magnitudes for an individual determination of ages and parallaxes, which have to be included in a more extensive work analyzing the kinematic properties of A V stars. Several calibrations and methods to determine the above mentioned parameters have been reviewed, allowing the design of a new algorithm for their determination. The results obtained using this procedure were tested in a previous paper using uvby H-beta data from the Hauck and Mermilliod catalogue, and comparing the rusulting temperatures, surface gravities and absolute magnitudes with empirical determinations of these parameters.

Measuring conduct and cost parameters in the Spanish air transport market

This paper estimates a model of airline competition for the Spanish air transport market. I test the explanatory power of alternative oligopoly models with capacity constraints. In addition, I analyse the degree of density economies. Results show that Spanish airlines conduct follows a price-leadership scheme so that it is less competitive than the Cournot solution. I also find evidence that thin routes can be considered as natural monopolies

Classical parameters of Shadowlands by Richard Attenborough (On C. S. Lewis's Life and Work)

The aim of this article is to show the classical parameters of Shadowlands by R. Attenborough, with a screenplay by W. Nicholson, on C. S. Lewis's life and work. Based upon an accurate reading of Lewis's works, the author of this article proposes to interpret the opposition Lewis / Gresham as the translation into the real life of the opposition between the Platonic or idealistic and the Aristotelian or materialistic temperaments which was already maintained by Coleridge. In any case, there are many classical references which must be taken into account in order to understand to what extent C. S. Lewis's Christianity is also a classic Christianity, that is, a Greek and Latin one.