On the use of scaling relations for the Tolman test

The use of relations between structural parameters of early type galaxies to perform the Tolman test is reconsidered. Scaling relations such as the FP or the Kormendy relation, require the transformation from angular to metric sizes, to compare the relation at different z values. This transformation depends on the assumed world model: galaxies of a given angular size, at a given z, are larger (in kpc) in a non-expanding universe than in an expanding one. Furthermore, the luminosities of galaxies are expected to evolve with z in an expanding model. These effects are shown to conspire to reduce the difference between the predicted SB change with redshift in the expanding and non expanding cases. We find that the predictions for the visible photometric bands of the expanding models with passive luminosity evolution are very similar to those of the static model till z about 1, and therefore, the test cannot distinguish between the two world models. Recent good quality data are consistent with the predictions from both models. In the K-band, where the expected (model) luminosity evolutionary corrections are smaller, the differences between the xpanding and static models amount to about 0.4 (0.8) magnitudes at z = 0.4 (1). It is shown that, due to that small difference between the predictions in the covered z-range, and to the paucity and uncertainties of the relevant SB photometry, the existing K-band data is not adequate to distinguish between the different world metrics, and cannot be yet used to discard the static case. It is pointed out that the scaling relations could still be used to rule out the non-evolving case if it could be shown that the coefficients change with the redshift.Comment: Latex, 15 pages with 2 figures. To be published in ApJ Letter

Evaluation of the growth-inhibitory effect of trifluralin analogues on in vitro cultured Babesia bovis parasites

Bovine babesiosis, caused by Babesia bovis, is a global tick borne hemoprotozoan parasite disease characterized by fever, anemia, weight losses and ultimately death. Several babesicidal drugs that have been in use in cattle for years have proven to be only partially effective and the development of alternative chemotherapeutics that are highly specific and have low toxicity against babesiosis is needed. Trifluralin derivatives specifically bind alpha-tubulin in plants and protozoa parasites causing growth inhibition. A set of 12 trifluralin analogues (TFLA) has previously been shown to be inhibitory for the growth of Leishmania species. The conservation of several key amino acids involved in the trifluralin binding site of alpha-tubulin among Leishmania sp. and B. bovis provides rationale for testing these compounds also as babesiacides. The previously tested Leishmania inhibitory, TFLA 1-12 minus TFLA 5, in addition to three novel TFLA (termed TFLA 13-15), were tested against in vitro cultured B. bovis parasites. While all of the TFLA tested in the study showed inhibition of B. bovis growth in vitro TFLA 7, TFLA 10 and TFLA 13, were the most effective inhibitors with estimated IC50 (μM) at 72h of 8.5±0.3; 9.2±0.2; 8.9±0.7, respectively for the biologically attenuated cloned B. bovis Mo7 strain, and 13.6±1.5; 18.7±1.6; 10.6±1.9, respectively for the virulent B. bovis T3Bo strain. The differences found between the two strains were not statistically significant. Importantly, these drugs displayed low levels of toxicity for the host erythrocytes and bovine renal arterial endothelial cells at the doses tested. The demonstrated ability of trifluralin analogues to inhibit in vitro growth of B. bovis parasites combined with their low toxicity for host cells suggests that these compounds may be further developed as novel alternatives for the treatment of bovine babesiosis.publishersversionpublishe

Connected Classroom Climate and Communication in the Basic Course: Associations with Learning

Most research on the association between classroom climate and student learning has emphasized the instructor’s role in creating a positive learning environment. However, the role students play in fostering a classroom climate that promotes learning has received less attention, particularly in the basic course. This study examined the relationship between perceptions of a connected classroom climate and students’ cognitive and affective learning involving 437 freshman and sophomore university students enrolled in the basic public speaking course. Students completed the Connected Classroom Climate Inventory (CCCI) and scales measuring affective and cognitive learning. Results showed significant relationships between student perceptions of connected classroom climate and cognitive learning, affective learning, and affective behavioral intent

Modeling the functional network of primary intercellular Ca2+^{2+} wave propagation in astrocytes and its application to study drug effects

We introduce a simple procedure of multivariate signal analysis to uncover the functional connectivity among cells composing a living tissue and describe how to apply it for extracting insight on the effect of drugs in the tissue. The procedure is based on the covariance matrix of time resolved activity signals. By determining the time-lag that maximizes covariance, one derives the weight of the corresponding connection between cells. Introducing simple constraints, it is possible to conclude whether pairs of cells are functionally connected and in which direction. After testing the method against synthetic data we apply it to study intercellular propagation of Ca$^{2+}$ waves in astrocytes following an external stimulus, with the aim of uncovering the functional cellular connectivity network. Our method proves to be particularly suited for this type of networking signal propagation where signals are pulse-like and have short time-delays, and is shown to be superior to standard methods, namely a multivariate Granger algorithm. Finally, based the statistical analysis of the connection weight distribution, we propose simple measures for assessing the impact of drugs on the functional connectivity between cells.Comment: 14 pages, 12 figure

Industrial symbiosis between the winery and environmental industry through the Utilization of grape marc for water desalination containing copper(II)

A bioadsorbent formulated with a secondary raw material, consisting of grape marc, subjected to a bioxidize process and entrapped in calcium alginate beads, was used for the desalination of water containing copper(II) sulfate. Experiments were established under different experimental conditions varying the concentration of contaminant, the amount of bioadsorbent, and the extraction time through response surface methodology. The most significant variable in the removal of copper(II) sulfate was the amount of bioadsorbent employed, followed by the extraction time; whereas, the adsorbent capacity was more influenced by the amount of contaminant and the amount of bioadsorbent used. At the highest concentration of copper(II) sulfate (0.15 mol/L), the equations obtained predict that the bioadsorbent has a capacity of 2785 mg/g and produces a copper(II) removal about 43% using low adsorbent/water ratios, 1:10 (v/v), and maximum extraction times; whereas, it would remove 97.2% of copper(II) sulfate in 5 min, using adsorbent/water ratios close to 1:2 (v/v), with capacity values, in this case, around 1800 mg/g. The encapsulation of the bioxidize adsorbent increased its capacity to 30% and allowed the precipitation of sulfate ions as calcium sulfate. The results obtained in this work could presume advances for promoting the industrial symbiosis between winery and environmental industries.Peer ReviewedPostprint (author's final draft

Multiscale understanding of tricalcium silicate hydration reactions

Tricalcium silicate, the main constituent of Portland cement, hydrates to produce crystalline calcium hydroxide and calcium-silicate-hydrates (C-S-H) nanocrystalline gel. This hydration reaction is poorly understood at the nanoscale. The understanding of atomic arrangement in nanocrystalline phases is intrinsically complicated and this challenge is exacerbated by the presence of additional crystalline phase(s). Here, we use calorimetry and synchrotron X-ray powder diffraction to quantitatively follow tricalcium silicate hydration process: i) its dissolution, ii) portlandite crystallization and iii) C-S-H gel precipitation. Chiefly, synchrotron pair distribution function (PDF) allows to identify a defective clinotobermorite, Ca11Si9O28(OH)2.8.5H2O, as the nanocrystalline component of C-S-H. Furthermore, PDF analysis also indicates that C-S-H gel contains monolayer calcium hydroxide which is stretched as recently predicted by first principles calculations. These outcomes, plus additional laboratory characterization, yielded a multiscale picture for C-S-H nanocomposite gel which explains the observed densities and Ca/Si atomic ratios at the nano- and meso- scales.This work has been supported by Spanish MINECO through BIA2014-57658-C2-2-R, which is co-funded by FEDER, BIA2014-57658-C2-1-R and I3 (IEDI-2016-0079) grants. We also thank CELLS-ALBA (Barcelona, Spain) for providing synchrotron beam time at BL04-MSPD beamline

X-ray near-field ptychographic nanoimaging of cement pastes

The hydration processes of Portland cements (PC) and blends are complicated as there are many components with great heterogeneity at different length scales. Thus, 3D nanoimaging techniques with high spatial resolution and scanning large fields of view are needed. Here, synchrotron X-ray near-field ptychographic tomography is used to investigate four pastes within 0.2 mm thick capillaries: PC with CaCl2, PC hydration enhanced by C-S-H nucleation seeding, PC partly substituted with metakaolin, and PC partly substituted with metakaolin and limestone. Data analysis emphasis has been placed on the characterization of amorphous components: (i) C-S-H and C-A-S-H gels; (ii) iron aluminium siliceous hydrogarnets; (iii) metakaolin; and (iv) aluminium carboaluminate, AFm-like. Synchrotron ptychotomography yields electron density and absorption coefficient tomograms and the resulting bivariate plots are instrumental for characterising these amorphous components. The attained spatial resolution, ∼220 nm, with very good contrast allowed us to determine nanofeatures including mass densities and spatial distributions of amorphous components. For instance, the C-S-H gel mass density differences between the two type of accelerated pastes are detailed.Funding for open access charge: Universidad de Málaga / CBUA. This research has been partly supported by the research grant PID2019-104378RJ-I00 which is co-funded by ERDF. We acknowledge the Paul Scherrer Institut, Villigen, Switzerland for provision of synchrotron radiation beamtime at cSAXS beamline of the SLS, proposal number 20210147

Caracterización de empresas acogidas a la ley 550 en Cartagena : caso Mideplast Ltda. y Suárez Betancourt Ltda

Según los análisis efectuados por Alberto Echavarría Saldarriaga1 , vicepresidente de asuntos jurídicos de la ANDI, desde comienzos del año 1999, el gobierno y particularmente la Superintendencia de Sociedades, inició un proceso de evaluación de la pertinencia de los procesos concursales existentes frente a las dificultades económicas de ese momento. Se observaba que las entidades financieras estaban seriamente afectadas por los créditos efectuados a las empresas en Concordato, lo que las obligaba a realizar elevadas provisiones. Además, el proceso concordatario planteaba muchas limitantes referidas al poder del veto2 , como la demora en los procesos concursales debido a las normas de procedimiento que los regulaba y las dificultades para llegar a un acuerdo por la prelación de créditos, entre otras. Tomando en consideración todo esto y las dificultades económicas de muchos empresarios del sector productivo, el gobierno decidió regular esta crisis mediante acuerdos preconcursales, que en principio se pensó, podrían hacer parte de un acápite especial y detallado en el Plan Nacional de Desarrollo de ese año, pero que por recomendaciones de la ANDI, no se hizo así, aunque el gobierno en el artículo 60 de este, se abrogó la facultad de reglamentar dichos acuerdos, para lo cual habría de determinar requisitos de validez, anexos, publicidad, efectos, garantías de cumplimiento y prelación de créditos. La gran preocupación inicial del gobierno fue sobre la efectividad de los acuerdos pre concursales, dado que habría que dotarlos de unas previsiones que iban en contra de varias leyes, lo que podría implicar excesos de la potestad reglamentaria, y en consecuencia, graves riesgos para los nuevos acuerdos.Incluye bibliografía, anexo

Connected Classroom Climate and Communication Apprehension: Correlations and Implications of the Basic Course

Although scholars have recommended increasing relational variables in the classroom such as familiarity, acquaintance level, and collaboration to help students moderate communication apprehension (CA), few, if any, academic studies have investigated the relationship between CA and a supportive climate among students in the college classroom. Self-report data were collected from 523 undergraduate students from a Midwestern university who participated in a large curriculum assessment program using the Connected Classroom Climate Inventory (CCCI) and the PRCA-24. Results showed significant relationships between student perceptions of connected-classroom climate and CA levels throughout the course