Models of cuspy triaxial stellar systems. II. Regular orbits

In the first paper of this series we used the N--body method to build a dozen cuspy (gamma ~ 1) triaxial models of stellar systems, and we showed that they were highly stable over time intervals of the order of a Hubble time, even though they had very large fractions of chaotic orbits (more than 85 per cent in some cases). The models were grouped in four sets, each one comprising models morphologically resembling E2, E3, E4 and E5 galaxies, respectively. The three models within each set, although different, had the same global properties and were statistically equivalent. In the present paper we use frequency analysis to classify the regular orbits of those models. The bulk of those orbits are short axis tubes (SATs), with a significant fraction of long axis tubes (LATs) in the E2 models that decreases in the E3 and E4 models to become negligibly small in the E5 models. Most of the LATs in the E2 and E3 models are outer LATs, but the situation reverses in the E4 and E5 models where the few LATs are mainly inner LATs. As could be expected for cuspy models, most of the boxes are resonant orbits, i.e., boxlets. Nevertheless, only the (x, y) fishes of models E3 and E4 amount to about 10 per cent of the regular orbits, with most of the fractions of the other boxlets being of the order of 1 per cent or less.Comment: Accepted for publication in the Monthly Notices of the Royal Astronomical Societ

Models of cuspy triaxial stellar systems. III: The effect of velocity anisotropy on chaoticity

In several previous investigations we presented models of triaxial stellar systems, both cuspy and non cuspy, that were highly stable and harboured large fractions of chaotic orbits. All our models had been obtained through cold collapses of initially spherical $N$--body systems, a method that necessarily results in models with strongly radial velocity distributions. Here we investigate a different method that was reported to yield cuspy triaxial models with virtually no chaos. We show that such result was probably due to the use of an inadequate chaos detection technique and that, in fact, models with significant fractions of chaotic orbits result also from that method. Besides, starting with one of the models from the first paper in this series, we obtained three different models by rendering its velocity distribution much less radially biased (i.e., more isotropic) and by modifying its axial ratios through adiabatic compression. All three models yielded much higher fractions of regular orbits than most of those from our previous work. We conclude that it is possible to obtain stable cuspy triaxial models of stellar systems whose velocity distribution is more isotropic than that of the models obtained from cold collapses. Those models still harbour large fractions of chaotic orbits and, although it is difficult to compare the results from different models, we can tentatively conclude that chaoticity is reduced by velocity isotropy.Comment: 11 pages, 14 figures. Accepted for publication in MNRA

The Grace and Call of the Hospitable God

John Navone explains how human hospitality “images the tri-personal God of Christians who is love.” He also discusses how Jesus’s parables invite us to participate in God’s hospitality and call us to be hospitable to others. Beauty is an important part of God’s hospitality because it is the aspect of the good that attracts us. Three moments of divine and human hospitality in salvation history are identified; in each, the human hosts meet God in the form of a stranger or strangers. Since the hospitality is freely given, it is reflective of grace and of our creation. We are given life out of “God sharing his bounty,” and therefore we must be generous. As Navone describes it, hospitality in the City of God “demand[s] a profound conversion of the heart and a conscious commitment to the quest for the common good.” Scriptural passages on hospitality are included

Cloning and expression of a human kinesin heavy chain gene: interaction of the COOH-terminal domain with cytoplasmic microtubules in transfected CV-1 cells.

To understand the interactions between the microtubule-based motor protein kinesin and intracellular components, we have expressed the kinesin heavy chain and its different domains in CV-1 monkey kidney epithelial cells and examined their distributions by immunofluorescence microscopy. For this study, we cloned and sequenced cDNAs encoding a kinesin heavy chain from a human placental library. The human kinesin heavy chain exhibits a high level of sequence identity to the previously cloned invertebrate kinesin heavy chains; homologies between the COOH-terminal domain of human and invertebrate kinesins and the nonmotor domain of the Aspergillus kinesin-like protein bimC were also found. The gene encoding the human kinesin heavy chain also contains a small upstream open reading frame in a G-C rich 5' untranslated region, features that are associated with translational regulation in certain mRNAs. After transient expression in CV-1 cells, the kinesin heavy chain showed both a diffuse distribution and a filamentous staining pattern that coaligned with microtubules but not vimentin intermediate filaments. Altering the number and distribution of microtubules with taxol or nocodazole produced corresponding changes in the localization of the expressed kinesin heavy chain. The expressed NH2-terminal motor and the COOH-terminal tail domains, but not the alpha-helical coiled coil rod domain, also colocalized with microtubules. The finding that both the kinesin motor and tail domains can interact with cytoplasmic microtubules raises the possibility that kinesin could crossbridge and induce sliding between microtubules under certain circumstances

Dirofilariosis canina: microfilaremia en perros de la ribera del Río de la Plata, Argentina

La dirofilariosis es una enfermedad zoonótica causada por Dirofilaria immitis y transmitida por mosquitos. Este trabajo presenta un relevamiento de la microfilaremia en perros en la ribera del Río de la Plata utilizando la técnica de Knott modificada y estudia posibles especies de mosquitos como vectores. A través de consultorios veterinarios y centros de zoonosis de Villa Domínico, Quilmes Este, La Plata y Berisso (Buenos Aires) se obtuvieron 265 muestras de sangre de perros y se completó una encuesta (sexo, edad, pedigree, talla, largo del pelo, manejo de las mascotas y tratamiento con ivermectina). Se capturaron y disecaron 412 mosquitos con aspirador manual sobre cebo humano en la ribera del Río de la Plata para observar formas filariformes. El 78,8% de las muestras de sangre correspondieron a hembras, el 76,2% de los perros fueron mestizos, las tallas chicas a medianas (30,1% y 41,1% respectivamente) y el 38,2% de las mascotas permanecía las 24 horas fuera de la vivienda. El 73% de las muestras correspondieron a perros menores de 6 años. Se detectaron 6 casos Knott positivos (prevalencia 2,26%). El 50% de los casos positivos eran asintomáticos. Si bien los machos estuvieron más parasitados que las hembras (diferencias significativas), se estima que ello está asociado a un manejo especial de las mascotas hembras por parte de los dueños. Éstas suelen permanecer mayor tiempo en el interior de la vivienda y así tendrían menor probabilidad de contacto con mosquitos. Se observaron diferencias significativas entre edades. Los adultos estuvieron más parasitados que los jóvenes. No se hallaron formas filariformes en los mosquitos disecados. Se recomienda el test de Knott modificado como técnica rápida, económica y efectiva para el diagnóstico de dirofilariosis, siempre que el canino no haya sido tratado con ivermectin

Evolución del grado de desertificación y su relación con los aspectos socioeconómicos en la cuenca del río Santa María, Catamarca, Argentina

298-308Este trabajo revisa las características del proceso de desertificación en los Valles Áridos con especial énfasis en la cuenca del río Santa María. Hace referencia al avance de la desertificación ocurrida entre 1997 y 2012 a través de un índice que fue construido a partir de la combinación de indicadores biofísicos. Habida cuenta de que es necesario relacionar la desertificación con indicadores socioeconómicos, se realizaron encuestas en el área bajo estudio para indagar sobre aspectos socioeconómicos, lo que permitió construir indicadores. Los resultados obtenidos indican que la desertificación ha aumentado en todos los casos, excepto en el sitio donde se aplican prácticas sustentables. Al mismo tiempo los indicadores socioeconómicos indican que un mayor grado de desertificación se presenta asociado a las explotaciones menores a la unidad económica, formas de tenencia más precarias, mayor inequidad en la distribución del ingreso y mayor pobreza e indigencia, superando ampliamente los valores nacionales y provinciales. Es por ello que la evaluación del grado de desertificación y su relación con indicadores socioeconómicos resulta imprescindible a fin de monitorear y revertir este proceso

Evolución del grado de desertificación y su relación con los aspectos socioeconómicos en la cuenca del río Santa María, Catamarca, Argentina

298-308Este trabajo revisa las características del proceso de desertificación en los Valles Áridos con especial énfasis en la cuenca del río Santa María. Hace referencia al avance de la desertificación ocurrida entre 1997 y 2012 a través de un índice que fue construido a partir de la combinación de indicadores biofísicos. Habida cuenta de que es necesario relacionar la desertificación con indicadores socioeconómicos, se realizaron encuestas en el área bajo estudio para indagar sobre aspectos socioeconómicos, lo que permitió construir indicadores. Los resultados obtenidos indican que la desertificación ha aumentado en todos los casos, excepto en el sitio donde se aplican prácticas sustentables. Al mismo tiempo los indicadores socioeconómicos indican que un mayor grado de desertificación se presenta asociado a las explotaciones menores a la unidad económica, formas de tenencia más precarias, mayor inequidad en la distribución del ingreso y mayor pobreza e indigencia, superando ampliamente los valores nacionales y provinciales. Es por ello que la evaluación del grado de desertificación y su relación con indicadores socioeconómicos resulta imprescindible a fin de monitorear y revertir este proceso

Biomolecular, histological, clinical, and radiological analyses of dental implant bone sites prepared using magnetic mallet technology: A pilot study in animals

Background. A new instrumentation exploiting magneto-dynamic technology (mallet) proposed for implant site preparation was investigated. Methods. In the tibias of three minipigs, two sites were prepared by mallet and two by drill technique. Primary stability (ISQ) was detected after implant positioning (T0) and at 14 days (T14). X-rays and computed tomography were performed. At T14, bone samples were utilized for histological and biomolecular analyses. Results. In mallet sites, histological evaluations evidenced a significant increase in the newly formed bone, osteoblast number, and a smaller quantity of fibrous tissue. These results agree with the significant BMP-4 augmentation and the positive trend in other osteogenic factors (biological and radiological investigations). Major, albeit IL-10-controlled, inflammation was present. For both techniques, at T14 a significant ISQ increase was evidenced, but no significant difference was observed at T0 and T14 between the mallet and drill techniques. In mallet sites, lateral bone condensation was observed on computed tomography. Conclusions. Using biological, histological, clinical, and radiological analyses, this study first shows that the mallet technique is effective for implant site preparation. Based on its ability to cause osseocondensation and improve newly formed bone, mallet technology should be chosen in all clinical cases of poor bone quality

Mechanistic studies on δ-aminolevulinic acid uptake and efflux in a mammary adenocarcinoma cell line

δ-aminolevulinic acid (ALA) is the precursor in the biosynthesis of porphyrins. The knowledge of both the regulation of ALA entrance and efflux from the cells and the control of porphyrin biosynthesis is essential to improve ALA-mediated photodynamic therapy. In this work, we studied the regulation of ALA uptake and efflux by endogenously accumulated ALA and/or porphyrins in murine mammary adenocarcinoma cells. Under our set of conditions, the haem synthesis inhibitor succinyl acetone completely prevented porphobilinogen and porphyrin synthesis from ALA, and led to an increase in the intracellular ALA pool. However, neither intracellular ALA nor porphyrin pools regulate ALA uptake or efflux during the first 15 min of the process. Based on temperature dependence data, ALA but not γ-aminobutyric acid (GABA) efflux is mediated by a diffusion mechanism. Moreover, the addition of extracellular GABA not only did not influence the rate of ALA efflux but on the contrary it affected ALA uptake, showing the contribution of a saturable mechanism for the uptake, but not for the efflux of ALA from the cells. © 2003 Cancer Research UK.Fil:Correa García, S. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Casas, A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Perotti, C. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Batlle, A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina.Fil:Bermúdez Moretti, M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

δ-Aminolevulinic acid transport in murine mammary adenocarcinoma cells is mediated by beta transporters

δ-aminolevulinic acid, the precursor of porphyrin biosynthesis has been used to induce the endogenous synthesis of the photosensitiser protoporphyrin IX for photodynamic therapy in the treatment of various tumours. The aim of this work was to characterise the δ-aminolevulinic acid transport system in the murine mammary adenocarcinoma cell line LM3 using 14C-δ-aminolevulinic acid, to finally improve δ-aminolevulinic acid incorporation in mammalian cells. Our results showed that δ-aminolevulinic acid is incorporated into these cells by two different mechanisms, passive diffusion which is important at the beginning of the incubation, and active transport. Specificity assays suggested that the transporter involved in δ-aminolevulinic acid incorporation is a BETA transporter, probably GAT-2