An overview of some mathematical models of blood rheology

Experimental investigations over many years reveal that blood flow exhibits non-Newtonian characteristics such as shear-thinning, viscoelasticity and thixotropic behaviour. The complex rheology of blood is influenced by numerous factors including plasma viscosity, rate of shear, hematocrit, level of erythrocytes aggregation and deformability. Hemodynamic analysis of blood flow in vascular beds and prosthetic devices requires the rheological behaviour of blood to be characterized through appropriate constitutive equations relating the stress to deformation and rate of deformation. The objective of this paper is to present a short overview of some macroscopic constitutive models that can mathematically characterize the rheology of blood and describe its known phenomenological properties. Some numerical simulations obtained in geometrically reconstructed real vessels will be also presented to illustrate the hemodynamic behaviour using Newtonian and non-Newtonian inelastic models under a given set of physiological flow conditions.info:eu-repo/semantics/publishedVersio

Arc routing with trip-balancing and attractiveness measures : A waste collection case study

This work focuses on a household (or door to door) waste collection problem in the Portuguese municipality of Seixal, which is modelled as a generalisation of a mixed capacitated arc routing problem (MCARP). The MCARP is known to be NP-hard. The proposed methodology uses: i) a GIS (geographic information system), for input/output and to reduce problem dimensions; ii) a matheuristic that iteratively solves a new hybrid model; and iii) two versions of a two-phase matheuristic. The latter pursues the generation of connected and compacted trips. During the first phase, called initial assignment, some links requiring service are assigned to vehicle services. In the second phase, the hybrid model finishes the assignment and generates a feasible set of trips. The quality of the generated solutions is assessed through the total time, as well as by some attractiveness measures. These measures evaluate the adequacy of the solutions for the real case-study, a crucial aspect for trips that need to be accepted by practitioners. With this purpose, a new attractiveness measure that introduces space dependent penalisation of overlaps, named weighted hull overlap, is also proposed. Computational results with 18 Seixal instances, with 265–1223 nodes and 492–2254 links, point to the good performance of the proposed.info:eu-repo/semantics/publishedVersio

An optimization based on simulation approach to the patient admission scheduling problem: Diagnostic imaging department case study

The growing influx of patients in healthcare providers is the result of an aging population and emerging self-consciousness about health. In order to guarantee the welfare of all the healthcare stakeholders, it is mandatory to implement methodologies that optimize the healthcare providers' efficiency while increasing patient throughput and reducing patient's total waiting time. This paper presents a case study of a conventional radiology workflow analysis in a Portuguese healthcare provider. Modeling tools were applied to define the existing workflow. Re-engineered workflows were analyzed using the developed simulation tool. The integration of modeling and simulation tools allowed the identification of system bottlenecks. The new workflow of an imaging department entails a reduction of 41 % of the total completion time. © 2013 Society for Imaging Informatics in Medicine

Intervenção da fisioterapia em doentes agudos com Covid-19 num hospital de referência: a experiência de um ano

Introdução e Objetivos: A pandemia Covid-19 lançou um desafio à intervenção do Fisioterapeuta. A evidência científica indica que a Fisioterapia tem um papel preponderante na recuperação destes doentes. Este trabalho tem como objectivo caracterizar os doentes com Covid-19 referenciados para a fisioterapia e descrever as estratégias de intervenção. Material e Métodos: Estudo descritivo de amostra consecutiva de doentes adultos com Covid-19 referenciados para fisioterapia num hospital de abril de 2020 a abril de 2021. Os doentes foram caracterizados por dados demográficos e clínicos. A funcionalidade foi classificada pela Escala de Mobilidade da UCI (EMUCI) e pela Medida de Independência Funcional (motora) (MIFm). Os dados foram analisados através de estatística descritiva. Resultados: 833 doentes foram referenciados para a fisioterapia, com idades compreendidas entre os 18 e os 100 anos (mediana de 74) e 54,7% eram homens. 88,6% internados por infeção a SARS-CoV2 e 11,4% por outros motivos, mas testaram positivo. Na UCI foram tratados 200 doentes, 36 faleceram, os restantes tiveram em média 13,6 dias de internamento e 6,7 sessões de fisioterapia. Os doentes melhoraram em média 1,3 pontos na EMUCI. Os problemas apresentados eram a dependência ventilatória e a imobilidade e a intervenção baseou-se no desmame ventilatório, controlo respiratório e estímulo da mobilidade ativa. Nas enfermarias 724 doentes beneficiaram do apoio da fisioterapia, 51 faleceram, os restantes tiveram em média 18,5 dias de internamento e 7,9 sessões de fisioterapia. Os doentes melhoraram em média 14,4 pontos na MIFm. As complicações cardiorrespiratórias e imobilidade eram os principais problemas e a intervenção da fisioterapia baseou-se em fisioterapia respiratória, incentivo e melhoria da mobilidade ativa, reeducação ao esforço e treino funcional com estratégias de conservação da energia. 347 doentes tiveram alta para a residência habitual, 204 transferidos para outra unidade hospitalar, 46 para a RNCCI, 34 para lar e 6 para outros destinos. Conclusões: O apoio da fisioterapia foi valorizado pela equipa multidisciplinar e pelos doentes contribuindo para a melhoria funcional dos doentes com Covid-19.info:eu-repo/semantics/publishedVersio

A one-dimensional model for unsteady axisymmetric swirling motion of a viscous fluid in a variable radius straight circular tube

A one-dimensional model for the flow of a viscous fluid with axisymmetric swirling motion is derived in the particular case of a straight tube of variable circular cross-section. The model is obtained by integrating the Navier-Stokes equations over cross section the tube, taking a velocity field approximation provided by the Cosserat theory. This procedure yields a one-dimensional system, depending only on time and a single spatial variable. The velocity field approximation satisfies exactly both the incompressibility condition and the kinematic boundary condition. From this reduced system, we derive unsteady equations for the wall shear stress and mean pressure gradient depending on the volume flow rate, the Womersley number, the Rossby number and the swirling scalar function over a finite section of the tube geometry. Moreover, we obtain the corresponding partial differential equation for the scalar swirling functio

Cinnamic acid derivatives: a contribution for the study of cyclooxygenase inhibition

Relatório de Estágio do Mestrado Integrado em Ciências Farmacêuticas apresentado à Faculdade de FarmáciaThe role of cyclooxygenase (COX) in inflammation, pain and fever has long been established: this enzyme catalyzes the conversion of arachidonic acid into prostaglandins G2 and then H2, with the latter being the substrate for the formation of other prostaglandins, as well as prostacyclin (PGI2) and thromboxane A2 (TxA2, stimulator of platelet activation and aggregation). COX inhibitors known as nonsteroidal anti-inflammatory drugs (NSAIDs) have long been used to treat the previously mentioned symptoms. Knowledge on this field was significantly upgraded when a second isoform of COX was discovered (COX-2). It is now accepted that COX-1 is mostly constitutively-expressed, assuring homeostasis and normal physiological function of the cells and tissues where it is found, while COX-2 is for the most part inducible-expressed, with a decisive role in inflammatory responses. Such findings led to the development of new drugs which specifically inhibit COX-2 – the coxibs. Following a number of studies with cinnamic acid derivatives, which revealed antioxidant and antitumoral activities, hexylamides of different cinnamic acids were synthesized and their inhibitory activity on COX-1 and COX-2 was assessed. The current monograph aims to present the synthesis methodologies for three of those hexylamides (as well as for more complex hexylamides which could be assessed for their COX-inhibiting activity in the future), along with the results of their COX-inhibiting activity studies. In addition to the monograph, this document contains two reports describing curricular internships in the fields of community pharmacy and pharmaceutical industry.O papel da ciclo-oxigenase (COX) em eventos como inflamação, dor e febre já é conhecido há muito tempo: esta enzima catalisa a conversão de ácido araquidónico em prostaglandina G2 seguida da H2, sendo que esta última serve como substrato para a formação de outras prostaglandinas, e ainda de prostaciclina (PGI2) e tromboxano A2 (TxA2, estimulador da ativação e agregação plaquetar). Os fármacos inibidores da COX, designados anti-inflamatórios não esteroides (AINEs), têm uma longa tradição de utilização no tratamento dos sintomas inicialmente referidos. O conhecimento a este nível sofreu uma atualização muito significativa quando foi descoberta uma segunda isoforma da COX (COX-2). Atualmente, considera-se que a COX-1 é expressa de modo constitutivo, sendo importante para a homeostase e para o funcionamento fisiológico normal das células e tecidos onde se encontra, enquanto a COX-2 é maioritariamente expressa de modo induzido, tendo um papel decisivo em episódios inflamatórios. Estas descobertas levaram ao desenvolvimento de novos fármacos que inibem especificamente a COX-2 – os coxibs. Na sequência de vários estudos que revelaram propriedades antioxidantes e antitumorais de derivados de ácidos cinâmicos, foram sintetizadas hexilamidas de diferentes ácidos cinâmicos e as suas atividades inibitórias sobre a COX-1 e a COX-2 foram avaliadas. A presente monografia pretende apresentar as metodologias de síntese de três destas hexilamidas (e ainda de outras hexilamidas, mais complexas, cuja atividade inibitória das COX poderá ser avaliada futuramente), bem como os resultados dos respetivos estudos da atividade inibitória das COX. Para além da monografia, este documento inclui dois relatórios que descrevem estágios curriculares realizados nas áreas de farmácia comunitária e indústria farmacêutica

Numerical simulation of generalized second-grade fluids using a 1D hierarchical model

We consider the flow of a non-Newtonian incompressible second-grade fluid in an uniform rec- tilinear pipe and generalize it by introducing a shear-dependent viscosity function of power law type. The full 3D set of equations is reduced to a one-dimensional problem involving only time and one spatial variable. This is done using a director theory for fluid dynamics, also called Cosserat theory. An axisym- metric unsteady relationship between mean pressure gradient and volume flow rate over a finite section of the pipe and the corresponding equation to the wall shear stress are derived from this theory

Mathematical Fluid Mechanics, a Tribute to Giovanni Paolo Galdi

This International Conference is warmly dedicated to Professor Giovanni Paolo Galdi on the occasion of his 60th birthday. The conference will honor his many outstanding contributions to the broad field of Mathematical Fluid Mechanics, and the inspiration, generosity and dedication he has provided to his friends, colleagues ans students during his creative scientific career. The conference is an excellent opportunity to bring together world leaders in theoretical, numerical and experimental Fluid Mechanics, Professor Galdi´s friends and collaborators, to celebrate this research field, highlighting its achievements and giving new insights to open problems. Our aim is also to promove the interaction and the exchange of ideas with younger researchers, and to stimulate international collaboration. This volumw contains a collection of abstracts corresponding to the invited and contributed lectures that will be delived during the conference. We would like to welcome all the participants and, in particular the invited speakers, who have enthusiastically accepted our invitation to this special occasion, since the start of the project. The financial and organization support of the following institutions, which made this conference possible, are gratefully acknowledged: Fundação para a Ciência e a Tecnologia (FACC Program); Fundação Calouste Gulbenkian; Fundação Luso-Americana para o Desenvolvimento; CEMAT-Center for Mathematics and its Applications, Instituto Superior Técnico. Lisbon, May 21, 2007 Adélia Sequeira, Fernando Carapau, João Janel