The domain interface method in non-conforming domain decomposition multifield problems.

The Domain Interface Method (DIM) is extended in this contribution for the case of mixed fields as encountered in multiphysics problems. The essence of the non-conforming domain decomposition technique consists in a discretization of a fictitious zero-thickness interface as in the original methodology and continuity of the solution fields across the domains is satisfied by incorporating the corresponding Lagrange Multipliers. The multifield DIM inherits the advantages of its irreducible version in the sense that the connections between non-matching meshes, with possible geometrically non-conforming interfaces, is accounted by the automatic Delaunay interface discretization without considering master and slave surfaces or intermediate surface projections as done in many established techniques, e.g. mortar methods. The multifield enhancement identifies the Lagrange multiplier field and incorporates its contribution in the weak variational form accounting for the corresponding consistent stabilization term based on a Nitsche method. This type of constraint enforcement circumvents the appearance of instabilities when the Ladyzhenskaya-Babuska-Brezzi (LBB) condition is not fulfilled by the chosen discretization. The domain decomposition framework is assessed in a large deformation setting for mixed displacement/pressure formulations and coupled thermomechanical problems. The continuity of the mixed field is studied in well selected benchmark problems for both mixed formulations and the objectivity of the response is compared to reference monolithic solutions. Results suggest that the presented strategy shows sufficient potential to be a valuable tool in situations where the evolving physics at particular domains require the use of different spatial discretizations or field interpolations.

The domain interface method: a general-purpose non-intrusive technique for non-conforming domain decomposition problems.

A domain decomposition technique is proposed which is capable of properly connecting arbitrary non-conforming interfaces. The strategy essentially consists in considering a fictitious zero-width interface between the non-matching meshes which is discretized using a Delaunay triangulation. Continuity is satisfied across domains through normal and tangential stresses provided by the discretized interface and inserted in the formulation in the form of Lagrange multipliers. The final structure of the global system of equations resembles the dual assembly of substructures where the Lagrange multipliers are employed to nullify the gap between domains. A new approach to handle floating subdomains is outlined which can be implemented without significantly altering the structure of standard industrial finite element codes. The effectiveness of the developed algorithm is demonstrated through a patch test example and a number of tests that highlight the accuracy of the methodology and independence of the results with respect to the framework parameters. Considering its high degree of flexibility and non-intrusive character, the proposed domain decomposition framework is regarded as an attractive alternative to other established techniques such as the mortar approach.

Vademecum-based approach to multi-scale topological material design.

The work deals on computational design of structural materials by resorting to computational homogenization and topological optimization techniques. The goal is then to minimize the structural (macro-scale) compliance by appropriately designing the material distribution (microstructure) at a lower scale (micro-scale), which, in turn, rules the mechanical properties of the material. The specific features of the proposed approach are: (1) The cost function to be optimized (structural stiffness) is defined at the macro-scale, whereas the design variables defining the micro-structural topology lie on the low scale. Therefore a coupled, two-scale (macro/micro), optimization problem is solved unlike the classical, single-scale, topological optimization problems. (2) To overcome the exorbitant computational cost stemming from the multiplicative character of the aforementioned multiscale approach, a specific strategy, based on the consultation of a discrete material catalog of micro-scale optimized topologies (Computational Vademecum) is used. The Computational Vademecum is computed in an offline process, which is performed only once for every constitutive-material, and it can be subsequently consulted as many times as desired in the online design process. This results into a large diminution of the resulting computational costs, which make affordable the proposed methodology for multiscale computational material design. Some representative examples assess the performance of the considered approach.

Validation of a device for transcorneal drug permeation measure.

A model of a corneal apparatus for the study of drug permeation across the corneal tissues is evaluated. The instrument was designed to measure drug transport in living rabbit corneas, which are placed hermetically into a chamber, separating it into two compartments (epithelial and endothelial). The device also allows the measurement and recording of the corneal potential, providing information on the vitality of the cornea. The validation of the instrument was carried out by introducing variable amounts of fluorescein into the epithelial compartment of the chamber, and measuring the concentration of the dye by the fluorescence obtained in the endothelial compartment. The fluorescein concentration in the endothelial compartment increased exponentially over time, with a good correlation between the epithelial and endothelial concentrations. The repeatability of the measurements is strongly influenced by the maintenance and regularity of the initial concentration, the time that has passed from the beginning of the experiment, and the corneal potential (vitality of the cornea). Less important are slight modifications to temperature, the agitation system and hydrostatic pressure (robustness). The proposed experimental system shows good precision when measuring the permeation through rabbit cornea at different drug concentrations, and good repeatability and intermediate precision with non-significant differences among operators in repeated experiments. It is a good approach for comparing corneal transport of different formulations of the same drug. To test the method with real samples, different formulations of the NSAID sodium diclofenac where assayed. Corneal permeation was remarkably enhanced when diclofenac was formulated as a beta-cyclodextrin complex. Other additives, such as the surfactants used in commercial eye drops, also enhanced corneal drug transport.

Flurbiprofen loaded biodegradable nanoparticles for ophtalmic administration.

Poly(lactic/glycolic) acid nanoparticles incorporating flurbiprofen (FB) were prepared by the solvent displacement technique using poloxamer 188 as a stabilizer to improve the availability of the drug for the prevention of the inflammation caused by ocular surgery. A 2(3) + star design was applied to investigate the influence of several factors such as the pH of the aqueous phase, the initial concentration of the stabilizer, and the drug used to prepare the nanoparticles (NPs) on the physicochemical properties (particle size analysis, zeta potential, and drug loading efficiency) of the colloidal system. The best formulations were those prepared at pH 3.5 with a concentration of 1.5 mg/mL of FB and 10 or 20 mg/mL of poloxamer 188. These formulations showed an appropriate average size for ophthalmic administration (232.8 and 277.6 nm, respectively) and a good yield of entrapment efficiency (94.60% and 93.55%, respectively). The release behavior of FB from the developed NPs was complete and exhibited a biphasic pattern. Formulations did not show toxicity on ocular tissues. In vivo anti-inflammatory efficacy was assessed in the rabbit eye after topical instillation of sodium arachidonate (SA). A higher decrease of the SA-induced inflammation was obtained for the NP formulations.

Stability and ocular tolerance of cyclophosphamide-loaded nanospheres.

The physical and chemical stabilities of several formulations of cyclophosphamide-loaded polybutylcyanoacrylate (PBCA) nanospheres developed for an ophthalmic application as an immunosuppressive agent were studied over 6 months of storage at 4, 25 and 40 degrees C in different experimental conditions. The physical stability of nanospheres was followed by the study of morphological (visual appearance) and morphometrical properties (mean particle size and polydispersity). The pH and tonicity of the suspensions and the association efficiency of the drug to polymeric system were also analysed to evaluate their chemical stability. The behaviour of colloidal suspensions with storage conditions was also followed by differential scanning calorimetry. The degradation of PBCA was affected by temperature and pH. The average particle size of all nanospheres remained practically unchanged throughout the study, with the polydispersity index being less than 0.1, corresponding to a monodisperse system. At 40 degrees C, a loss of 25.9% of the initial association efficiency, especially in non-buffered pH 7.2 medium, was observed. The type of polymer degradation (surface erosion) was also determined by photon correlation spectroscopy. The results obtained from in vivo study of ocular tolerance indicate a good ocular tolerance for drug loaded to nanospheres.

Determinación de ibupofreno asociadoa nanoesferas de poli-E-caprolactona / Determination of Ibuprofen loaded poly-E-caprolactone nanoespheres

Se ha puesto a punto y validado un nuevo método para la determinación de un antiinflamatorio no esteroideo, ibuprofeno, asociado a nanoesferas de poli-E-caprolactona, por espectroscopia de fluorescencia. Los valores de exactitud, precisión y linealidad demostraron la validez del mismo, siendo la sensibilidad, 7,89 10-6 mg/ml, idónea para este tipo de análisis. Los resultados obtenidos pusieron de relieve que el método analítico desarrollado es adecuado para la determinación de ibuprofeno asociado a sistema matriciales de poli-E-caprolactona (AU)

Vortex lattice melting in layered superconductors with periodic columnar pins.

The melting of the vortex lattice in highly anisotropic, layered superconductors with commensurate, periodic columnar pins is studied in a geometry where magnetic field and columnar pins are normal to the layers. Thermodynamic properties and equilibrium density distributions are obtained from numerical minimization of an appropriate free-energy functional. We find a line of first-order transitions that ends at a critical point as the pin concentration is increased. We quantitatively determine the location of this critical point and show that it is experimentally accessible.

Aceclofenac-loaded poly-epsilon-caprolactone nanocapsules. Effect of coadjuvants on morphometrical properties and drug entrapment.

The physicochemical properties of aceclofenac nanocapsules, prepared by interfacial precipitation of poly-e-caprolactone at the oil/water interface, have been studied. A Central Composite Design was used to investigate the influence of polymerization adjuvants on these properties on the elaboration of aceclofenac-loaded poly-e-caprolactone nanocapsules. In this way, the effect of polymer, oil and drug concentrations in organic phase on the size and encapsulation efficiency has been analyzed. The optimized nanocapsule formulation leads to use an initial concentration of drug (aceclofenac) of 0.8 mg/ml and 0.6% of oil (Miglyol 812), being the polymer and surfactant concentrations previously fixed.

Estabilidad del aceclofenaco asociado a sistemas poliméricos / Aceclofenac stability associated to polymeric systems

Teniendo en cuenta las aplicaciones oculares del aceclofenaco, se prepararon nanocápsulas de este fármaco, utilizando dos polímeros distintos, poli-isobutilcianoacrilato y poli-s-caprolactona. Dependiendo del tipo de polímero utilizado, de las concentraciones iniciales de fármaco y de aceite (Miglyol°) y del pH; las eficiencias de asociación obtenidas se encuentran en un intervalo comprendido entre 63 y 95 por ciento, con un tamaño promedio entre 211 y 077 nm. Este parámetro fue, en todos los casos, lo suficientemente pequeño para no producir molestias después de su instilación ocular. Los valores de polidispersión (0) son mayores cuando las partículas se obtienen con isobutilcianoacrilato. La temperatura (>25°C) y el tiempo de almacenamiento conducen a la agregación y la degradación de las nanocápsulas de aceclofenaco a partir de los 60 o 90 días, según el polímero utilizado. La agregación se detectó primero con la poli-epsilon-caprolactona. No se observaron diferencias significativas en la degradación y en la polidispersión al utilizar uno ú otro polímero. El contenido de fármaco ( por ciento) disminuye regularmente al aumentar la temperatura y el tiempo, para ambos polímeros (AU)

Asociación de ciclofosfamida a nanoesferas de polibutil-cianoacrilato / Association of cycle phosphamide to nanospheres of alkylcyanoacrilate

En este trabajo se ha llevado a cabo un estudio de la asociación de un agente citostático, cíclofosfamida, a sistemas biodegradables de alquilcianoacrilatos, poli-butil-2-cianoacrilato, en forma de nanoesferas, analizando el efecto de diversas variables de la formulación -concentración de principio activo, monómero, tensioactivo y agente suspensór-, en las características morfométricas de las partículas por espectroscopia de correlación fotóníca y en la eficiencia de asociación de fármaco al polímero por espectroscopia de plasma de acoplamiento inductivo (AU)

[Pharmacokinetics of vancomycin in neonates of postconceptional age less than or equal to 32 weeks]. / Comportamiento farmacocinético de la vancomicina en neonatos de edad postconcepcional < or = 32 semanas. Propuesta de una pauta de dosificación.

The objective of the present study was to analyze the pharmacokinetic behavior of vancomycin in neonates of postconceptional age < or = 32 weeks (n = 44). The elimination of the antibiotic was influenced by the concomitant treatment with indomethacin and mechanical ventilation. Close monitoring of renal function of the neonate and vancomycin dosage individualization are mandatory when the above factors are present. Vancomycin dosage guidelines have been determined according to serum creatinine of these premature patients.

[Sepsis caused by coagulase-negative Staphylococcus in the newborn infant. Clinical and therapeutic aspects]. / Sepsis por estafilococo coagulasa negativo en el recién nacido. Aspectos clínicos y terapéuticos.

This study deals with sepsis caused by coagulase-negative stapylococci in a neonatal intensive care unit over a period of four years and eleven months. The global incidence was 20.7/1000 (50 cases out of a total of 2,416 admissions) and was higher in newborns with lower weight and with a shorter gestational age. The most significant clinical manifestations were fever, paleness, and apnea/bradycardia. In all cases the germ was sensitive to vancomycin. Evolution was favourable in all patients, in spite of the initial gravity of some cases. Sepsis due to coagulase-negative staphylococci is the most frequent cause of nosocomial infection in our environment.

[Leiomyosarcoma of the vena cava inferior. The correlation: ultrasound and fine-needle puncture biopsy]. / Leiomiosarcoma de vena cava inferior. Correlación: ultrasonido y punción biopsia con aguja fina.

The leiomyosarcoma of the inferior vena cava is a non-frequent tumor, mesenchymal, that has its origin in the smooth muscular tissue of the vascular wall. Its growth is slow and expansive, more frequently found on females. The symptomatology is related to the cava segment where it is located. The diagnosis is performed by ultrasonics, computed tomography and cavography, actually magnetic resonance acquires more and more importance. The treatment is specifically surgery along with radiotherapy and chemotherapy. A case of leiomyosarcoma of the inferior vena cava is presented in which diagnosis was performed using ultrasonics, tomography and cavography confirmed before surgery by biopsy punction with thin needle. In the diagnosis of this pathology it is described the use of intro-surgery ultrasonics.

[Marginality, ethnic groups and health]. / Marginalidad, grupos étnicos y salud.

Main marginated ethnic groups in Span are to be found among gypsies and 3rd world immigrants. The first group include about 250,000 persons and the second group more tan half a million people. Their origins and their being past of the less fortunate social layers made them a group of health risk. Pediatric pathologies are those favored by socio-economic shortcomings as well as hygienic-sanitary deficiencies. Imported pediatric pathologies have a small incident.

PIP: Marginalized ethnic groups in Spain consist primarily of some 250,000 gypsies and over half million immigrants from Third World countries who began to seek work in newly industrialized Spain beginning around 1970. The numbers of immigrants doubled between 1970-85 and immigration continues from Latin America, Africa south of the Sahara, North America, and the Philippines. Over 300,000 are believed to be undocumented, and around 23% are under 16 years old. This large scale immigration in a traditional country of emigration has created previously unknown problems for the health services. Health personnel still lack adequate knowledge of the cultural patterns, illnesses and needs of these groups, and frequent difficulties of communication complicate problems. Immigrants frequently initiate contact with the health services in search of treatment for their children, who are considered a population at risk. Imported diseases from the region of origin progressively lose importance as the immigrants are assimilated, typically into the least prosperous classes. Their illnesses lose specificity, and perinatal and early childhood problems emerge as the predominant concerns. Imported problems may include genetically determined illnesses such as sickle cell anemia, infectious and parasitic diseases prevalent in the region of origin, or pathologies contracted directly from indigenous medical treatments. Ailments of children acquired in Spain include the normal childhood diseases, with respiratory and gastrointestinal infections most common, dehydration caused by dietary errors, rickets, chronic lead poisoning caused by old paint in the dwelling, and accidents. Pathologies of adaptation may include other diseases but are typically psychic disorders resulting from the 2 greatest disadvantages facing immigrants: poverty and racism. Greater perinatal morbidity and mortality and more frequent and longer hospitalizations of infants and children are 2 consequences. The degree of marginalization experienced by gypsies in Spain depends somewhat on their region of residence. In recent years they have tended to cluster in periurban zones outside the large cities, where their neighbors live in similar poverty and share the same diseases of deprivation. Pediatric health problems are similar to those acquired in Spain by immigrant children. Gypsies have higher rates of fertility and infant mortality. Gypsy children are at higher risk of tuberculosis, malnutrition, accidents, dental caries, sand drug consumption, and they are less likely to be immunized. They are a recognized risk group for iron deficiency anemia and lead poisoning, and their rates of hospitalization and consultations in emergency rooms are elevated.

[Duodenal duplication cyst]. / Duplicación quística duodenal.

The duodenal duplication cyst is an uncommon inherited anomaly. Its etiology is related to malformations of the canal in the gastrointestinal duct during the formation of the embryo. It develops in the infancy period or during childhood, it is uncommon in adults. The most frequent finding, is abdominal mass, although it might appear along with obstructive symptoms, recidivante pancreatitis and digestive bleeding. The diagnosis is based on image methods (ultrasonics, radiology, computed tomography, CPRE), nevertheless its identification through ultrasonics is of great value. Therefore we consider important the introduction of a 72-year-old woman case, whose pre-surgery diagnosis was performed with ultrasonics and reaffirmed by all other image methods. We also mention the usefulness of inner-surgery ultrasonics, in the surgery case of this pathology.

Tear pH, air pollution, and contact lenses.

We analyzed the tear pH of a random sample of 100 subjects, divided into 3 groups according to the stability of their precorneal tear film (normal eyes, borderline; and dry eyes). The average pH value obtained was 7.52. The pH for borderline and dry eyes was higher than for normal eyes. The purpose of this study was to determine the influence of air pollution, specifically sulfur dioxide (SO2), on the tear pH. We found that air pollution affected the lacrimal pH, which decreased when the atmospheric SO2 increased. Finally, we studied the effect of soft contact lens wear on tear pH after 7 days of contact lens adaptation by assessing the tear pH decrease. We took into account the influence of the sex and age of subjects on the results obtained.

[Leukemoid reactions in premature neonates with a very low birth weight]. / Reacciones leucemoides en recién nacidos prematuros con muy bajo peso al nacer.

Authors present three cases of leukemoid reaction in very low birth weight preterm infants. Hematologic evolution is detailed and was characterized by the presence of intense leukocytosis with marked shift to the left abundant immature forms. Leukocyte counts reached values of 70,000 and 106,000/mm3 between the second and third day of life, becoming normal around the eight day. No pathology known to cause such intense leukocytosis was observed in any case. Bibliography is reviewed and possible etiology is discussed, as until now this entity has been attributed to prenatal administration of glucocorticoids.