Study on tracheal collapsibility, compliance, and stress by considering nonlinear mechanical property of cartilage

Tracheal cartilage has been widely regarded as a linear elastic material either in experimental studies or in analytic and numerical models. However, it has been recently demonstrated that, like other fiber-oriented biological tissues, tracheal cartilage is a nonlinear material, which displays higher strength in compression than in extension. Considering the nonlinearity requires a more complex theoretical frame work and costs more to simulate. This study aims to quantify the deviation due to the simplified treatment of the tracheal cartilage as a linear material. It also evaluates the improved accuracy gained by considering the nonlinearity. Pig tracheal rings were used to exam the mechanical properties of cartilage and muscular membrane. By taking into account the asymmetric shape of tracheal cartilage, the collapse behavior of complete rings was simulated, and the compliance of airway and stress in the muscular membrane were discussed. The results obtained were compared with those assuming linear mechanical properties. The following results were found: (1) Models based on both types of material properties give a small difference in representing collapse behavior; (2) regarding compliance, the relative difference is big, ranging from 10 to 40% under negative pressure conditions; and (3) the difference in determining stress in the muscular membrane is small too: <5%. In conclusion, treating tracheal cartilage as a linear material will not cause big deviations in representing the collapse behavior, and mechanical stress in the muscular part, but it will induce a big deviation in predicting the compliance, particularly when the transmural pressure is lower than -0.5 kPa. The results obtained in this study may be useful in both understanding the collapse behavior of trachea and in evaluating the error induced by the simplification of treating the tracheal cartilage as a linear elastic material.

Study of tracheal collapsibility, compliance and stress by considering its asymmetric geometry

The shape of tracheal cartilage has been widely treated as symmetric in analytical and numerical models. However, according to both histological images and in vivo medical image, tracheal cartilage is of highly asymmetric shape. Taking the cartilage as symmetric structure will induce bias in calculation of the collapse behavior, as well as compliance and muscular stress. However, this has been rarely discussed. In this paper, tracheal collapse is represented by considering its asymmetric shape. For comparison, the symmetric shape, which is reconstructed by half of the cartilage, is also presented. A comparison of cross-sectional area, compliance of airway and stress in the muscular membrane, determined by asymmetric shape and symmetric shape is made. The result indicates that the symmetric assumption brings a small error, around 5% in predicting the cross-sectional area under loading conditions. The relative error of compliance is more than 10%. Particularly when the pressure is close to zero, the error could be more than 50%. The model considering the symmetric shape results in a significant difference in predicting stress in muscular membrane by either under- or over-estimating it. In conclusion, tracheal cartilage should not be treated as a symmetric structure. The results obtained in this study are helpful in evaluating the error induced by the assumption in geometry.

Nonlinear mechanical property of tracheal cartilage: A theoretical and experimental study

Background: Despite being the stiffest airway of the bronchial tree, the trachea undergoes significant deformation due to intrathoracic pressure during breathing. The mechanical properties of the trachea affect the flow in the airway and may contribute to the biological function of the lung. Method: A Fung-type strain energy density function was used to investigate the nonlinear mechanical behavior of tracheal cartilage. A bending test on pig tracheal cartilage was performed and a mathematical model for analyzing the deformation of tracheal cartilage was developed. The constants included in the strain energy density function were determined by fitting the experimental data. Result: The experimental data show that tracheal cartilage is a nonlinear material displaying higher strength in compression than in tension. When the compression forces varied from -0.02 to -0.03 N and from -0.03 to -0.04 N, the deformation ratios were 11.03±2.18% and 7.27±1.59%, respectively. Both were much smaller than the deformation ratios (20.01±4.49%) under tension forces of 0.02 to 0.01 N. The Fung-type strain energy density function can capture this nonlinear behavior very well, whilst the linear stress-strain relation cannot. It underestimates the stability of trachea by exaggerating the displacement in compression. This study may improve our understanding of the nonlinear behavior of tracheal cartilage and it may be useful for the future study on tracheal collapse behavior under physiological and pathological conditions.

Phylodynamic evidence of the migration of turnip mosaic potyvirus from Europe to Australia and New Zealand

Turnip mosaic virus (TuMV) is a potyvirus that is transmitted by aphids and infects a wide range of plant species. We investigated the evolution of this pathogen by collecting 32 isolates of TuMV, mostly from Brassicaceae plants, in Australia and New Zealand. We performed a variety of sequence-based phylogenetic and population genetic analyses of the complete genomic sequences and of three non-recombinogenic regions of those sequences. The substitution rates, divergence times and phylogeographical patterns of the virus populations were estimated. Six inter- and seven intralineage recombination-type patterns were found in the genomes of the Australian and New Zealand isolates, and all were novel. Only one recombination-type pattern has been found in both countries. The Australian and New Zealand populations were genetically different, and were different from the European and Asian populations. Our Bayesian coalescent analyses, based on a combination of novel and published sequence data from three nonrecombinogenic protein-encoding regions, showed that TuMV probably started to migrate from Europe to Australia and New Zealand more than 80 years ago, and that distinct populations arose as a result of evolutionary drivers such as recombination. The basal-B2 subpopulation in Australia and New Zealand seems to be older than those of the world-B2 and -B3 populations. To our knowledge, our study presents the first population genetic analysis of TuMV in Australia and New Zealand. We have shown that the time of migration of TuMV correlates well with the establishment of agriculture and migration of Europeans to these countries.

Conservadurismo, negación y diáspora

This contribution deals with social and political aspects affecting cultural life in Jalisco (Mexico), during the last forty years. It is, especially, a critical view on the regional deterioration of experimental music, analysing ethnic, religion, gender and other social components in one of the culturally foremost states of Mexico.

Relaxor Ferroelectric Behavior and Structural Aspects of SrNaBi2Nb3O12 Ceramics

The SrNaBi2Nb3O12 (SNBN) powder was prepared via the conventional solid-state reaction method. X-ray structural studies confirmed the phase to be a three-layered member of the Aurivillius family of oxides. The SNBN ceramics exhibited the typical characteristics of relaxor ferroelectrics, associated with broad and dispersive dielectric maxima. The variation of temperature of dielectric maxima (T-m) with frequency obeyed the Vogel-Fulcher relationship. Relaxor behavior was believed to be arising from the cationic disorder at A-site. Pinched ferroelectric hysteresis loops were observed well above T-m.

Raman scattering, microstructural and dielectric studies on Ba1-xCaxBi4Ti4O15 ceramics

Polycrystalline powders of Ba1-xCaxBi4Ti4O15 (where x = 0, 0.25, 0.50, 0.75 and 1) were prepared via the conventional solid-state reaction route. X-ray diffraction (XRD) and Raman scattering techniques have been employed to probe into the structural changes on changing x. XRD analyses confirmed the formation of monophasic bismuth layered structure of all the above compositions with an increase in orthorhombic distortion with increase in x. Raman spectra revealed a redshift in A(1g) peak and an increase in the B-2g/B-3g splitting with increasing Ca content. The average grain size was found to increase with increasing x. The temperature of the maximum dielectric constant (T-m) increased linearly with increasing Ca-content whereas the diffuseness of the phase transition was found to decrease with the end member CaBi4Ti4O15 showing a frequency independent sharp phase transition around 1048 K. Ca doping resulted in a decrease in the remnant polarization and an increase in the coercive field. Ba0.75Ca0.25Bi4Ti4O15 ceramics showed an enhanced piezoelectric coefficient d(33) of 15 pC N-1 at room temperature. Low values of dielectric losses and tunability of temperature coefficient of dielectric constant (tau(epsilon)) in the present solid-solution suggest that these compounds can be of potential use in microwave dielectrics at high temperatures. (C) 2012 Elsevier B.V. All rights reserved.

Nonlinear dielectric response of BaBi4Ti4O15 ceramics

Nonlinear dielectric response of BaBi4Ti4O15 ceramics synthesized via the conventional solid-state reaction route has been monitored over a wide range of electric field strengths (E-0 = 0.5 - 5 kV/cm). Dielectric permittivity was found to increase linearly within the range of applied field. Rayleigh relations were employed to interpret the nonlinear dielectric response and the contribution of irreversible domain wall motion to the macroscopic permittivity was separated. The values of room temperature Rayleigh dielectric coefficient (alpha) and relative initial permittivity (epsilon'(init)) were found to be 2.28 +/- 0.02 cm/kV and 146.10 +/- 0.07, respectively. A reasonable agreement between the simulated and measured polarization-electric field (P-E) hysteresis loops was observed at an applied electric field of 5 kV/cm.

Enriching the annotation of Mycobacterium tuberculosis H37Rv proteome using remote homology detection approaches: Insights into structure and function

The availability of the genome sequence of Mycobacterium tuberculosis H37Rv has encouraged determination of large numbers of protein structures and detailed definition of the biological information encoded therein; yet, the functions of many proteins in M. tuberculosis remain unknown. The emergence of multidrug resistant strains makes it a priority to exploit recent advances in homology recognition and structure prediction to re-analyse its gene products. Here we report the structural and functional characterization of gene products encoded in the M. tuberculosis genome, with the help of sensitive profile-based remote homology search and fold recognition algorithms resulting in an enhanced annotation of the proteome where 95% of the M. tuberculosis proteins were identified wholly or partly with information on structure or function. New information includes association of 244 proteins with 205 domain families and a separate set of new association of folds to 64 proteins. Extending structural information across uncharacterized protein families represented in the M. tuberculosis proteome, by determining superfamily relationships between families of known and unknown structures, has contributed to an enhancement in the knowledge of structural content. In retrospect, such superfamily relationships have facilitated recognition of probable structure and/or function for several uncharacterized protein families, eventually aiding recognition of probable functions for homologous proteins corresponding to such families. Gene products unique to mycobacteria for which no functions could be identified are 183. Of these 18 were determined to be M. tuberculosis specific. Such pathogen-specific proteins are speculated to harbour virulence factors required for pathogenesis. A re-annotated proteome of M. tuberculosis, with greater completeness of annotated proteins and domain assigned regions, provides a valuable basis for experimental endeavours designed to obtain a better understanding of pathogenesis and to accelerate the process of drug target discovery. (C) 2014 Elsevier Ltd. All rights reserved.

An estimate of the number of tropical tree species

The high species richness of tropical forests has long been recognized, yet there remains substantial uncertainty regarding the actual number of tropical tree species. Using a pantropical tree inventory database from closed canopy forests, consisting of 657,630 trees belonging to 11,371 species, we use a fitted value of Fisher's alpha and an approximate pantropical stem total to estimate the minimum number of tropical forest tree species to fall between similar to 40,000 and similar to 53,000, i.e., at the high end of previous estimates. Contrary to common assumption, the Indo-Pacific region was found to be as species-rich as the Neotropics, with both regions having a minimum of similar to 19,000-25,000 tree species. Continental Africa is relatively depauperate with a minimum of similar to 4,500-6,000 tree species. Very few species are shared among the African, American, and the Indo-Pacific regions. We provide a methodological framework for estimating species richness in trees that may help refine species richness estimates of tree-dependent taxa.

SInCRe-structural interactome computational resource for Mycobacterium tuberculosis

We have developed an integrated database for Mycobacterium tuberculosis H37Rv (Mtb) that collates information on protein sequences, domain assignments, functional annotation and 3D structural information along with protein-protein and protein-small molecule interactions. SInCRe (Structural Interactome Computational Resource) is developed out of CamBan (Cambridge and Bangalore) collaboration. The motivation for development of this database is to provide an integrated platform to allow easily access and interpretation of data and results obtained by all the groups in CamBan in the field of Mtb informatics. In-house algorithms and databases developed independently by various academic groups in CamBan are used to generate Mtb-specific datasets and are integrated in this database to provide a structural dimension to studies on tuberculosis. The SInCRe database readily provides information on identification of functional domains, genome-scale modelling of structures of Mtb proteins and characterization of the small-molecule binding sites within Mtb. The resource also provides structure-based function annotation, information on small-molecule binders including FDA (Food and Drug Administration)-approved drugs, protein-protein interactions (PPIs) and natural compounds that bind to pathogen proteins potentially and result in weakening or elimination of host-pathogen protein-protein interactions. Together they provide prerequisites for identification of off-target binding.

Caracterizacion de sistemas de produccion bovina en el municipio de San Pedro de Lovago - Chontales

El presente trabajo se llevó a cabo en 64 fincas seleccionadas al azar ubicadas en 15 comarcas con el objetivo de realizar una caracterización de los sistemas de producción bovina de doble prepósito en el municipio de San Pedro de Lóvago, Chontales. El estudio se desarrolló en cuatro fases: Realización de la encuesta a los productores, elaboración de la base de datos, el análisis estadístico y redacción de resultados utilizando los programas computarizados Excel, Access y Word. Se realizó una caracterización general de las fincas y se analizaron siete componentes obteniendo los siguientes resultados: Características generales de las fincas: El 85.93% de los productores poseen fincas con extensiones menores de 100mz, dedicadas más del 90% de su superficie a la actividad ganadera; el total de ganado perteneciente a los productores consultados es de 4775 cabezas lo que representa aproximadamente el 10% del total de cabezas de este municipio; el 81.75% poseen únicamente corrales de alambre de púas; el 62.5% de las fincas consultadas tienen principalmente ríos y quebradas como fuente de abastecimiento de agua para el ganado; sólo el 34.37% de las fincas se benefician de la asistencia técnica brindada a los productores por parte de las cooperativas; el 92% de los productores consultados obtienen el mayor ingreso de sus fincas a través de la venta de leche. Caracterización del manejo del ganado: el 58.81% de los productores consultados se dedican a la explotación de doble propósito; la producción de leche promedio por vaca/día es de 3.4l; el 65% de los productores llevan registros de su ganado aunque solo registran un tipo de evento, ya sea de nacimiento, pesaje de leche o reproductivo; el 85.94% de estos productores realizan trashumancia de todo el ganado, cuya actividad la desarrollan mayormente en el mes de enero. Caracterización del manejo de la sanidad animal: Ninguno de los productores consultados posee y cumplen con un calendario zoosanitario completo en sus fincas. Caracterización del manejo reproductivo: Se caracteriza por la poca atención reproductiva a las vacas, y en casos necesarios la realiza el mismo productor; los problemas reproductivos lo representan en su mayoría la retención de placenta con un 43.75%. Manejo genético y razas de interés para el mejoramiento: Las razas predominantes en los hatos son las de origen cebuino , las que representan el 57.81% del hato; entre los sementales utilizados el 56.26% pertenecen a las razas Pardo Suizo y Holstein; en la actualidad solamente el 4.68% de los productores están utilizan do la técnica de inseminación artificial, para llevar a cabo el mejoramiento genético del ganado. Caracterización del manejo de la alimentación del ganado: La alimentación del ganado es a base de pasturas en su mayoría naturales; el 51.56% de las fincas están divididas ente 6-10 potreros; El 75% de los productores suministran sales minerales a su ganado. Comercialización de la leche y carne: El 89.06% de los productores comercializan su leche a través de las cooperativas, la mayoría de los productores realizan sus transacciones comerciales de ganado en pie (novillos y vacas de descarte) a través de intermediarios.

Efecto de diferentes niveles y fraccionamiento de nitrógeno sobre el crecimiento y rendimiento del cultivo de ajonjolí (Sesamun indicum L.) variedad cuyumaqui

El presente trabajo se planificó con el propósito de determinar la influencia de diferentes niveles de nitrógeno (O, 29.62, 59.24 y 88.86 kg/ha) y fraccionamiento (100% 25 dds; 50%25 dds; 50%45 dds y 100 % 45 dds) del nitrógeno sobre el crecimiento y rendimiento del cultivo del ajonjolí (Sesamum indicun L), variedad Cuyumaqui y aná1isis económico de los tratamientos en estudio, bajo las condiciones ecológicas de la finca La Concepción, Nagarote, León. El ensayo se estableció en la siembra de Postrera de 1999 (13 de Septiembre al 22 de Diciembre de 1999), utilizándose un diseño de bloques completos al azar con arreglos en parcelas divididas y estableciéndose cuatro repeticiones. Los resultados estadísticos mostraron efecto real de los niveles del Factor A (dosis de nitrógeno) para las variables altura de planta, diámetro del tallo, hojas por planta cápsulas por planta y rendimiento de grano. Para el Factor B (fraccionamiento del nitrógeno) no se encontró diferencias estadísticas para el diámetro del tallo, número de hojas por planta y peso de mil semillas. El efecto de la interacción de los factores en estudio (AxB) mostró diferencias significativas en todos los caracteres evaluados, a excepción del peso de mil semilla que resultó ser no significativo. Los resultados del análisis económico indican que cuando se aplicó toda la dosis de 59.24 kg/ha de nitrógeno a los 25 días después de la siembra (dds), se obtuvo la más alta rentabilidad e económica (a3b1), con un rendimiento de 1089.30 kg de grano por hectarea y una tasa de retorno marginal de 439.29 por ciento.

Prudentia Iuris, 1993, n° 32-33 (número completo)

Contenido: Elementos para una definición del Derecho Internacional Privado / Raúl Alberto Ramayo – Elementos para determinar la jurisdicción ius privatista internacional / Raúl Alberto Ramayo – Mediación : elabore y decida su propia solución / Zulema Wilde – Contratos informáticos en la Argentina / Pablo Andrés Palazzi – El honor y la censura : ¿una contradicción? / Flavio F. Agatiello Piñero – La filosofía del derecho de Hegel y el catolicismo / Ignacio Andereggen – El arte político de los cristianos para la construcción de la ciudad del hombre / Franco Biffi – Servio Tulio, rey censor / Alfredo Grieco y Bavio – Una cuestión filosófica en el quinto centenario : ¿fue legítimo el imperio hispánico en América? / Héctor H. Hernández

Prudentia Iuris, 1983, n° 10 (número completo)

Contenido: Editorial – El Código de Derecho Canónico de 1983 / Alejandro Gagliardo – Ley, costumbre y actos administrativos en el nuevo Código de Derecho Canónico / Pedro Lombardía – Reflexión iusfilosófica sosbre la naturaleza jurídica del dictamen y la profesión de abogar / Jorge Guillermo Portela – La igualdad : consideración iusfilosófica / Siro de Martini – Juicio prudencial y razonamiento jurídico en las indemnizaciones por daños a la persona / Héctor Pedro Iribarne – La jurisdicción naval militar en el Río de la Plata (1748-1895) / Guillermo Palombo – Escolios – Documentos – Notas bibliográficas