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## Estudo do comportamento hemodinâmico, da troca gasosa, da mecânica respiratória e da análise do muco brônquico na aplicação de técnicas de remoção de secreção brônquica em pacientes sob ventilação mecânica; Airway clearance techniques in patients submitted to mechanical ventilation: A hemodynamic, gas exchange, respiratory mechanics and bronquial sputum study

Rodrigues, Marcus Vinicius Herbst
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
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INTRODUÇÃO: A aspiração traqueal (ASP) é um procedimento de rotina em pacientes sob ventilação mecânica, porém em algumas situações pode não ser eficiente. Como adjuvante usa-se a técnica "Bag-Squeezing" (BS) que consiste na hiperinflação manual associada à compressão torácica manual expiratória seguida ASP. Embora efetiva esta técnica pode apresentar algumas limitações como a desconexão do ventilador mecânico, além do controle precário do pico de pressão inspiratória (PPI) e pico de fluxo inspiratório (PFI). Como opção, podemos substituir o ressuscitador manual pelo próprio ventilador mecânico, alterando seus parâmetros e evitando assim a desconexão. Propusemos padronizar esta técnica e denominá-la PEEP-ZEEP (PZ); realizando-se a inflação dos pulmões aumentando a PEEP em 10 cmH2O, por 5 ciclos respiratórios, seguido de rápida descompressão pulmonar pela redução abrupta da PEEP até 0 cmH20, simultâneo à compressão torácica manual. OBJETIVOS: Avaliar o comportamento hemodinâmico, da troca gasosa e da mecânica respiratória, na aplicação das técnicas ASP, BS e PZ e seus efeitos na remoção de secreções brônquicas em pacientes ventilados mecanicamente. MÉTODO: 1ª etapa - "Pacientes sem secreção brônquica" estudamos prospectivamente 45 pacientes...

## Análise da estrutura molecular de compostos orgânicos por difração de raios-x e mecânica molecular.; Molecular structure analysis of organic compounds by X-ray diffraction and molecular mechanics.

Costa, Maria Cristina Nonato
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
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Este trabalho visou a análise estrutural de três compostos orgânicos: [A] : (2SR, 8SR)-2-(8-O-borinil-8-fenil)etil piperidina (C17H28NOB), [B] : (1SR, 2SR)-1-p-Bromoanilina-1-fenil-2-metil-3-pentanona -(C18H20NOBr) e [C] : um triterpeno-(C30O3H46) por difração de raio-X e por mecânica molecular. As estruturas no estado sólido foram primeiramente obtidas por difração de raios-x por monocristais, e posteriormente analisadas por mecânica molecular. [A]: monoclínico, grupo espacial C2/c, a=15.259(3)Å, b=12.574(2)Å, c=17.413(5)Å, β=94.44°, Z=8, Dx=1.089 g/cm3, V=3331.45޵ as estruturas cristalográficas e por mecânica molecular não apresentam grandes desvios. [B]: triclínico, grupo espacial P1¯, a=8.467(7)Å, b=8.7361(3)Å, c=12.468(9)Å, α=82.401(5)°, β=83.096(6)°, ϒ=69.026(5)°, Z=2, Dx=1.430 g/cm3, V=850.95޵ a principal diferença entre as duas estruturas cristalográfica e por mecânica molecular está no ângulo de torsão C(2)-C(1)-N-C(8) de 59.8°. Entre as moléculas relacionadas pelo centro de inversão existe duas pontes de hidrogênio entre os átomos O-N. [C]: ortorrômbico, grupo espacial P212121, a=7.314(7)Å, b=12.807(3)Å, c=26.812(5)Å...

## Contribuições à mecânica dos sistemas de massa variável.; Contributions to the mechanics of variable mass systems.

Casetta, Leonardo
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Relevância na Pesquisa
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Desde 1814, quando então se deram seus primeiros estudos, a mecânica de sistemas de massa variável tem se constituído como um ramo particular dentro da mecânica clássica. Suas aplicações encontram-se espalhadas por diversas áreas do conhecimento e vão desde a engenharia até a medicina, por exemplo. No entanto, apesar dessas aplicações de sucesso, ainda hoje são encontradas na literatura discussões acerca dos fundamentos da mecânica de sistemas de massa variável. Nesse cenário, figuram os chamados aparentes paradoxos que envolvem diferentes equações de movimento para um mesmo sistema de massa variável. É o que pode ser encontrado, por exemplo, com relação ao problema de Wagner, no âmbito do estudo do impacto de corpos sólidos contra superfícies de líquidos, e ao problema da corrente em queda. Nessa tese, questões como essas serão abordadas. Mas o cerne do escopo do presente trabalho é a apresentação de uma discussão de caráter mais geral e interpretativa sobre a teoria e aplicação da mecânica de sistemas de massa variável, mantendo-se como foco principal a contribuição para um melhor entendimento desse importante ramo da mecânica. Para tal, resultados teóricos originais serão apresentados...

## Qualificando solos para revestimentos primários de rodovias : uma abordagem baseada nas mecânicas dos solos e dos pavimentos; Qualifying soils for road wearing courses : an approach based on mechanics of pavements and soil mechanics

Peraça, Vinícius
Tipo: Dissertação Formato: application/pdf
POR
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## Statistical mechanics for biological applications: Focusing on the immune system

ASTI, LORENZO
EN
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The emergence in the last decades of a huge amount of data in many fields of biology triggered also an increase of the interest by quantitative disciplines for life sciences. Mathematics, physics and informatics have been providing quantitative models and advanced statistical tools in order to help the understanding of many biological problems. Statistical mechanics is a field that particularly contributed to quantitative biology because of its intrinsic predisposition in dealing with systems of many strongly interacting agents, noise, information processing and statistical inference. In this Thesis a collection of works at the interphase between statistical mechanics and biology is presented. In particular they are related to biological problems that can be mainly reconducted to the biology of the immune system. Beyond the unification key given by statistical mechanics of discrete systems and quantitative modeling and analysis of the immune system, the works presented here are quite diversified. The origin of this heterogeneity resides in the intent of using and learning many different techniques during the lapse of time needed for the preparation of the work reviewed in this Thesis. In fact the work presented in Chapter 3 mainly deals with statistical mechanics...

## A generic mechanics approach for predicting shear strength of reinforced concrete beams.

Zhang, Tao
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This thesis includes a series of journal articles in which a mechanics based segmental approach is developed for simulating shear behaviour of reinforced concrete (RC) beams. Using the well-established theories of partial interaction and shear friction, the generic mechanics approach simulates the formation and widening of diagonal cracks and shear sliding failure for RC beams. Being mechanics based, the proposed approach can be generally applied to various kinds of structures, that is any cross section, with any type of concrete and reinforcement and with any bond properties. Moreover, no component of the proposed approach relies on empiricism to account for the mechanics of shear failure, and the approach can accommodate any material characteristics which with time can be refined and revisited to improve the accuracy of shear strength simulation. In developing the mechanics of the segmental approach for prestressed RC beams, it is shown how the approach is applied to analyse shear behaviour and simulate shear failure of prestressed beams. Parametric studies are conducted to explain the effect of prestress on shear behaviour. For verification, the proposed approach is applied to 102 specimens and the analytical and experimental results are in good agreement. The generic nature of the mechanics approach is shown by its application to steel and fibre-reinforced polymer (FRP) reinforced beams and one-way slabs without stirrups. From the mechanics of the segmental approach...

## Henri Poincaré: The Status of Mechanical Explanations and the Foundations of Statistical Mechanics

Príncipe, João
Tipo: Parte de Livro
ENG
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The first goal of this paper is to show the evolution of Poincaré’s opinion on the mechanistic reduction of the principles of thermodynamics, placing it in the context of the science of his time. The second is to present some of his work in 1890 on the foundations of statistical mechanics. He became interested first in thermodynamics and its relation with mechanics, drawing on the work of Helm-holtz on monocyclic systems. After a period of skepticism concerning the kinetic theory, he read some of Maxwell’s memories and contributed to the foundations of statistical mechanics. I also show that Poincaré's contributions to the founda-tions of statistical mechanics are closely linked to his work in celestial mechanics and its interest in probability theory and its role in physics.

## 8.333 Statistical Mechanics, Fall 2002; Statistical Mechanics

Fonte: MIT - Massachusetts Institute of Technology Publicador: MIT - Massachusetts Institute of Technology
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EN-US
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8.333 is the first course in a two-semester sequence on statistical mechanics. Basic principles are examined in 8.333: the laws of thermodynamics and the concepts of temperature, work, heat, and entropy. Postulates of classical statistical mechanics, micro canonical, canonical, and grand canonical distributions; applications to lattice vibrations, ideal gas, photon gas. Quantum statistical mechanics; Fermi and Bose systems. Interacting systems: cluster expansions, van der Waal's gas, and mean-field theory.

## 8.334 Statistical Mechanics II, Spring 2003; Statistical Mechanics II

Levitov, Leonid
Fonte: MIT - Massachusetts Institute of Technology Publicador: MIT - Massachusetts Institute of Technology
EN-US
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A two-semester course on statistical mechanics. Basic principles are examined in 8.333: the laws of thermodynamics and the concepts of temperature, work, heat, and entropy. Postulates of classical statistical mechanics, microcanonical, canonical, and grand canonical distributions; applications to lattice vibrations, ideal gas, photon gas. Quantum statistical mechanics; Fermi and Bose systems. Interacting systems: cluster expansions, van der Waal's gas, and mean-field theory. Topics from modern statistical mechanics are explored in 8.334: the hydrodynamic limit and classical field theories. Phase transitions and broken symmetries: universality, correlation functions, and scaling theory. The renormalization approach to collective phenomena. Dynamic critical behavior. Random systems.

## Ultrastructural and cellular basis for the development of abnormal myocardial mechanics during the transition from hypertension to heart failure

Shah, Sanjiv J.; Aistrup, Gary L.; Gupta, Deepak K.; O'Toole, Matthew J.; Nahhas, Amanda F.; Schuster, Daniel; Chirayil, Nimi; Bassi, Nikhil; Ramakrishna, Satvik; Beussink, Lauren; Misener, Sol; Kane, Bonnie; Wang, David; Randolph, Blake; Ito, Aiko; Wu, M
Fonte: American Physiological Society Publicador: American Physiological Society
Tipo: Artigo de Revista Científica
EN
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Although the development of abnormal myocardial mechanics represents a key step during the transition from hypertension to overt heart failure (HF), the underlying ultrastructural and cellular basis of abnormal myocardial mechanics remains unclear. We therefore investigated how changes in transverse (T)-tubule organization and the resulting altered intracellular Ca2+ cycling in large cell populations underlie the development of abnormal myocardial mechanics in a model of chronic hypertension. Hearts from spontaneously hypertensive rats (SHRs; n = 72) were studied at different ages and stages of hypertensive heart disease and early HF and were compared with age-matched control (Wistar-Kyoto) rats (n = 34). Echocardiography, including tissue Doppler and speckle-tracking analysis, was performed just before euthanization, after which T-tubule organization and Ca2+ transients were studied using confocal microscopy. In SHRs, abnormalities in myocardial mechanics occurred early in response to hypertension, before the development of overt systolic dysfunction and HF. Reduced longitudinal, circumferential, and radial strain as well as reduced tissue Doppler early diastolic tissue velocities occurred in concert with T-tubule disorganization and impaired Ca2+ cycling...

## Statistical mechanics of reparametrization invariant systems. Takes Three to Tango

Josset, Thibaut; Chirco, Goffredo; Rovelli, Carlo
Tipo: Artigo de Revista Científica
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It is notoriously difficult to apply statistical mechanics to generally covariant systems, because the notions of time, energy and equilibrium are seriously modified in this context. We discuss the conditions under which weaker versions of these notions can be defined, sufficient for statistical mechanics. We focus on reparametrization invariant systems without additional gauges. The key idea is to reconstruct statistical mechanics from the ergodic theorem. We find that a suitable split of the system into two non-interacting components is sufficient for generalizing statistical mechanics. While equilibrium acquires sense only when the system admits a suitable split into three weakly interacting components ---roughly: a clock and two systems among which a generalization of energy is equi-partitioned. The key property that allows the application of statistical mechanics and thermodynamics is an additivity condition of such generalized energy.; Comment: 9 pages, 2 figures

## The Universal Arrow of Time II: Quantum mechanics case

Kupervasser, Oleg
Tipo: Artigo de Revista Científica
RU
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This paper is a natural continuation of our previous paper arXiv:1011.4173 . We illustrated earlier that in classical Hamilton mechanics, for overwhelming majority of real chaotic macroscopic systems, alignment of their thermodynamic time arrows occurs because of their low interaction. This fact and impossibility to observe entropy decrease at introspection explain the second law of thermodynamics. The situation in quantum mechanics is even a little bit easier: all closed systems of finite volume are periodic or nearly periodic. The proof in quantum mechanics is in many respects similar to the proof in classical Hamilton mechanics - it also uses small interaction between subsystems and impossibility to observe entropy decrease at introspection. However, there are special cases which were not found in the classical mechanics. In these cases one microstate corresponds to a set of possible macrostates (more precisely, their quantum superposition). Consideration of this property with use of decoherence theory and taking into account thermodynamic time arrows will introduce new outcomes in quantum mechanics. It allows to resolve basic paradoxes of quantum mechanics: (a) to explain the paradox of wave packet reduction at measurements when an observer is included in the system (introspection) (paradox of the Schrodinger cat); (b) to explain unobservability of superposition of macroscopic states by an external observer in real experiments (paradox of Wigner's friend); (c) to prove full equivalence of multi-world and Copenhagen interpretations of quantum mechanics; (d) to explain deviations from the exponential law at decay of particles and pass from one energy level to another (paradox of a kettle which will never begin to boil).; Comment: 42 pages in Enlish and in Russian

## Nonextensive statistical mechanics: A brief introduction

Tsallis, Constantino; Brigatti, Edgardo
Tipo: Artigo de Revista Científica
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Boltzmann-Gibbs statistical mechanics is based on the entropy $S_{BG}=-k \sum_{i=1}^W p_i \ln p_i$. It enables a successful thermal approach of ubiquitous systems, such as those involving short-range interactions, markovian processes, and, generally speaking, those systems whose dynamical occupancy of phase space tends to be ergodic. For systems whose microscopic dynamics is more complex, it is natural to expect that the dynamical occupancy of phase space will have a less trivial structure, for example a (multi)fractal or hierarchical geometry. The question naturally arises whether it is possible to study such systems with concepts and methods similar to those of standard statistical mechanics. The answer appears to be {\it yes} for ubiquitous systems, but the concept of entropy needs to be adequately generalized. Some classes of such systems can be satisfactorily approached with the entropy $S_q=k\frac{1-\sum_{i=1}^W p_i^q}{q-1}$ (with $q \in \cal R$, and $S_1 =S_{BG}$). This theory is sometimes referred in the literature as {\it nonextensive statistical mechanics}. We provide here a brief introduction to the formalism, its dynamical foundations, and some illustrative applications. In addition to these, we illustrate with a few examples the concept of {\it stability} (or {\it experimental robustness}) introduced by B. Lesche in 1982 and recently revisited by S. Abe.; Comment: Invited paper to appear in "Extensive and non-extensive entropy and statistical mechanics"...

## Partition Functions for Statistical Mechanics With MicroPartitions and Phase Transitions

Patwardhan, Ajay
Tipo: Artigo de Revista Científica
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The fundamentals of Statistical Mechanics require a fresh definition in the context of the developments in Classical Mechanics of integrable and chaotic systems. This is done with the introduction of Micro Partitions ; a union of disjoint components in phase space. Partition functions including the invariants, Kolmogorov Entropy and Euler number are introduced. The ergodic hypothesis for partial ergodicity is discussed. In the context of Quantum Mechanics the presence of symmetry groups with irreducible representations gives rise to degenerate and non degenerate spectrum for the Hamiltonian. Quantum Statistical Mechanics is formulated including these two cases ; by including the multiplicity dimension of the group representation and the Casimir invariants into the Partition function. The possibility of new kinds of phase transitions is discussed. The occurence of systems with non simply connected configuration spaces and Quantum Mechanics for them, also requires a possible generalisation of Statistical Mechanics. The developments of Quantum pure, mixed, and entangled states has made it neccessary to understand the Statistical Mechanics of the multipartite N particle system. And to obtain in terms of the density matrices, written in energy basis...

## Time and probability: From classical mechanics to relativistic Bohmian mechanics

Nikolic, H.
Tipo: Artigo de Revista Científica
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Bohmian mechanics can be generalized to a relativistic theory without preferred foliation, with a price of introducing a puzzling concept of spacetime probability conserved in a scalar time. We explain how analogous concept appears naturally in classical statistical mechanics of relativistic particles, with scalar time being identified with the proper time along particle trajectories. The conceptual understanding of relativistic Bohmian mechanics is significantly enriched by this classical insight. In particular, the analogy between classical and Bohmian mechanics suggests the interpretation of Bohmian scalar time as a quantum proper time different from the classical one, the two being related by a nonlocal scale factor calculated from the wave function. In many cases of practical interest, including the macroscopic measuring apparatus, the fundamental spacetime probability explains the more familiar space probability as an emergent approximate description. Requiring that the quantum proper time in the classical limit should reduce to the classical proper time, we propose that only massive particles have Bohmian trajectories. An analysis of the macroscopic measuring apparatus made up of massive particles restores agreement with the predictions of standard quantum theory.; Comment: 53 pages...

## Principles of classical statistical mechanics: A perspective from the notion of complementarity

Velazquez, L.
Tipo: Artigo de Revista Científica
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Quantum mechanics and classical statistical mechanics are two physical theories that share several analogies in their mathematical apparatus and physical foundations. In particular, classical statistical mechanics is hallmarked by the complementarity between two descriptions that are unified in thermodynamics: (i) the parametrization of the system macrostate in terms of mechanical macroscopic observables $I=\{I^{i}\}$; and (ii) the dynamical description that explains the evolution of a system towards the thermodynamic equilibrium. As expected, such a complementarity is related to the uncertainty relations of classical statistical mechanics $\Delta I^{i}\Delta \eta_{i}\geq k$. Here, $k$ is the Boltzmann's constant, $\eta_{i}=\partial \mathcal{S}(I|\theta)/\partial I^{i}$ are the restituting generalized forces derived from the entropy $\mathcal{S}(I|\theta)$ of a closed system, which is found in an equilibrium situation driven by certain control parameters $\theta=\{\theta^{\alpha}\}$. These arguments constitute the central ingredients of a reformulation of classical statistical mechanics from the notion of complementarity. In this new framework, Einstein postulate of classical fluctuation theory $dp(I|\theta)\sim\exp[\mathcal{S}(I|\theta)/k]dI$ appears as the correspondence principle between classical statistical mechanics and thermodynamics in the limit $k\rightarrow0$...

## On the relation between the second law of thermodynamics and classical and quantum mechanics

Drossel, Barbara
Tipo: Artigo de Revista Científica
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In textbooks on statistical mechanics, one finds often arguments based on classical mechanics, phase space and ergodicity in order to justify the second law of thermodynamics. However, the basic equations of motion of classical mechanics are deterministic and reversible, while the second law of thermodynamics is irreversible and not deterministic, because it states that a system forgets its past when approaching equilibrium. I argue that all "derivations" of the second law of thermodynamics from classical mechanics include additional assumptions that are not part of classical mechanics. The same holds for Boltzmann's H-theorem. Furthermore, I argue that the coarse-graining of phase-space that is used when deriving the second law cannot be viewed as an expression of our ignorance of the details of the microscopic state of the system, but reflects the fact that the state of a system is fully specified by using only a finite number of bits, as implied by the concept of entropy, which is related to the number of different microstates that a closed system can have. While quantum mechanics, as described by the Schroedinger equation, puts this latter statement on a firm ground, it cannot explain the irreversibility and stochasticity inherent in the second law.; Comment: Invited talk given on the 2012 "March meeting" of the German Physical Society To appear in: B. Falkenburg and M. Morrison (eds.)...

## The large deviation approach to statistical mechanics

Touchette, Hugo
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
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The theory of large deviations is concerned with the exponential decay of probabilities of large fluctuations in random systems. These probabilities are important in many fields of study, including statistics, finance, and engineering, as they often yield valuable information about the large fluctuations of a random system around its most probable state or trajectory. In the context of equilibrium statistical mechanics, the theory of large deviations provides exponential-order estimates of probabilities that refine and generalize Einstein's theory of fluctuations. This review explores this and other connections between large deviation theory and statistical mechanics, in an effort to show that the mathematical language of statistical mechanics is the language of large deviation theory. The first part of the review presents the basics of large deviation theory, and works out many of its classical applications related to sums of random variables and Markov processes. The second part goes through many problems and results of statistical mechanics, and shows how these can be formulated and derived within the context of large deviation theory. The problems and results treated cover a wide range of physical systems, including equilibrium many-particle systems...

## Quantum mechanics as an approximation of statistical mechanics for classical fields

Khrennikov, Andrei
Tipo: Artigo de Revista Científica
Relevância na Pesquisa
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We show that, in spite of a rather common opinion, quantum mechanics can be represented as an approximation of classical statistical mechanics. The approximation under consideration is based on the ordinary Taylor expansion of physical variables. The quantum contribution is given by the term of the second order. To escape technical difficulties, we start with the finite dimensional quantum mechanics. In our approach quantum mechanics is an approximative theory. It predicts statistical averages only with some precision. In principle, there might be found deviations of averages calculated within the quantum formalism from experimental averages (which are supposed to be equal to classical averages given by our model).; Comment: Talks at the conferences: "Quantum Theory: Reconsideration of Foundations-3", Vaxjo, Sweden, June-2005; "Processes in Physics", Askloster, Sweden, June-2005; "The nature of light: What is photon?", San-Diego, August-2005; "Nonlinear Physics. Theory and Experiment", Lece, Italy, July-2006

## Singular Lagrangian systems and variational constrained mechanics on Lie algebroids

Iglesias, David; Marrero, Juan Carlos; Martín de Diego, David; Sosa, Diana
Fonte: Conselho Superior de Investigações Científicas Publicador: Conselho Superior de Investigações Científicas
Tipo: Pre-print
ENG
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The purpose of this paper is to describe Lagrangian Mechanics for constrained systems on Lie algebroids, a natural framework which covers a wide range of situations (systems on Lie groups, quotients by the action of a Lie group, standard tangent bundles...). In particular, we are interested in two cases: singular Lagrangian systems and vakonomic mechanics (variational constrained mechanics). Several examples illustrate the interest of these developments.; This work has been partially supported by MEC (Spain) Grants MTM 2006-03322, MTM 2004-7832, project “Ingenio Mathematica” (i-MATH) No. CSD 2006-00032 (Consolider-Ingenio 2010) and S-0505/ESP/0158 of the CAM. D. Iglesias wants to thank MEC for a Research Contract "Juan de la Cierva".; Peer reviewed