Maximum likelihood inference for a class of discrete-time Markov-switching time series models with multiple delays

Autoregressive Markov switching (ARMS) time series models are used to represent real-world signals whose dynamics may change over time. They have found application in many areas of the natural and social sciences, as well as in engineering. In general, inference in this kind of systems involves two problems: (a) detecting the number of distinct dynamical models that the signal may adopt and (b) estimating any unknown parameters in these models. In this paper, we introduce a class of ARMS time series models that includes many systems resulting from the discretisation of stochastic delay differential equations (DDEs). Remarkably, this class includes cases in which the discretisation time grid is not necessarily aligned with the delays of the DDE, resulting in discrete-time ARMS models with real (non-integer) delays. We describe methods for the maximum likelihood detection of the number of dynamical modes and the estimation of unknown parameters (including the possibly non-integer delays) and illustrate their application with an ARMS model of El Ni\~no--southern oscillation (ENSO) phenomenon

Biglycan Modulation of Bone Morphogenetic Protein-2 Functions

Biglycan (BGN) is a proteoglycan found in high abundance in mineralized tissues. Study of its functions has unveiled roles in collagen organization (i.e. type VI), osteoblast differentiation, matrix mineralization, inflammatory processes, etc. Recently, we have reported that BGN promotion of osteoblast differentiation is due in part to its ability to positively modulate bone morphogenetic protein (BMP) functions. In the studies that follow, we (1) investigated the role of glycosaminoglycans (GAGs) of BGN on BGN-assisted BMP-2 function in vitro by utilizing a C2C12 cell system and in vivo by using a critical-sized mandible defect model in the Sprague-Dawley rat; (2) characterized by microcomputed tomography and histology the newly formed bone (NFB) in BGN-assisted BMP-2-induced osteogenesis; and (3) investigated which domain of the core protein of BGN is most effective in promoting BMP-2 function in vitro and applied it in vivo. We found that BGN devoid of GAGs is most effective in assisting BMP function in vitro and in vivo and that this positive modulation in vitro occurs through increased phosphorylation of Smad 1/5/8. In the animal model, rats treated with a low dose of BMP-2 in conjunction with appropriate dose of BGN formed a less porous and more mature type of bone than a high dose of BMP-2 alone. High dose BMP-2 formed an ectopic type of NFB and presented characteristics of a high turnover bone as per presence of osteoclast-like cells and yellow/orange picrosirius red staining. The BMP-2 and BMP-2 + BGN rats showed strong [beta]-catenin immunoreactivity at 2 weeks post-surgery. The rats that did not form significant amounts of bone did not show this pattern of staining. Finally, the effector domain of the core protein appears to reside between the N terminus and leucine rich repeat (LRR) 6, possibly in the LRR1~3. LRR1~3 was as effective as BGN full core protein in assisting BMP-2-induced osteogenesis in vivo. We conclude that the use of BGN or its effective domain combined with low concentrations of BMP-2 may be a more predictable, controllable and cost-effective approach than the use of high dose BMP-2

A likely magnetic activity cycle for the exoplanet host M dwarf GJ 3512

Current radial velocity data from specialized instruments contain a large amount of information that may pass unnoticed if their analysis is not accurate. The joint use of Bayesian inference tools and frequency analysis has been shown effective to reveal exoplanets but they have been used less frequently to investigate stellar activity. We intend to use radial velocity data of the exoplanet host star GJ 3512 to investigate its magnetic activity. Our study includes the analysis of the photometric data available. The main objectives of our work are to constrain the orbital parameters of the exoplanets in the system, to determine the current level of activity of the star and to derive an activity cycle length for it. An adaptive importance sampling method was used to determine the parameters of the exoplanets orbit. Generalized Lomb-Scargle periodograms were constructed with both radial velocity curve and photometric data. A careful analysis of the harmonic frequencies was conducted in each periodogram. Our fit to multiple Keplerian orbits constrained the orbital parameters of two giant gas planets orbiting the star GJ 3512. The host star showed an increase of its magnetic activity during the last observing campaign. The accurate fit of the radial velocity curve data to the multi-Keplerian orbit permitted to reveal the star rotation in the residuals of the best fit and estimate an activity cycle length of ~ 14 years.Comment: Accepted for publication in the Astronomical Journal. 15 pages, 11 figure

Do cover crops increase or decrease nitrous oxide emissions? A meta-analysis.

There are many environmental benefits to incorporating cover crops into crop rotations, such as their potential to decrease soil erosion, reduce nitrate (NO3) leaching, and increase soil organic matter. Some of these benefits impact other agroecosystem processes, such as greenhouse gas emissions. In particular, there is not a consensus in the literature regarding the effect of cover crops on nitrous oxide (N2O) emissions. Compared to site-specific studies, meta-analysis can provide a more general investigation into these effects. Twenty-six peer-reviewed articles including 106 observations of cover crop effects on N2O emissions from the soil surface were analyzed according to their response ratio, the natural log of the N2O flux with a cover crop divided by the N2O flux without a cover crop (LRR). Forty percent of the observations had negative LRRs, indicating a cover crop treatment which decreased N2O, while 60% had positive LRRs indicating a cover crop treatment which increased N2O. There was a significant interaction between N rate and the type of cover crop where legumes had higher LRRs at lower N rates than nonlegume species. When cover crop residues were incorporated into the soil, LRRs were significantly higher than those where residue was not incorporated. Geographies with higher total precipitation and variability in precipitation tended to produce higher LRRs. Finally, data points measured during cover crop decomposition had large positive LRRs and were larger than those measured when the cover crop was alive. In contrast, those data points measuring for a full year had LRRs close to zero, indicating that there was a balance between periods when cover crops increased N2O and periods when cover crops decreased emissions. Therefore, N2O measurements over the entire year may be needed to determine the net effect of cover crops on N2O. The data included in this meta-analysis indicate some overarching crop management practices that reduce direct N2O emissions from the soil surface, such as no soil incorporation of residues and use of non-legume cover crop species. However, our results demonstrate that cover crops do not always reduce direct N2O emissions from the soil surface in the short term and that more work is needed to understand the full global warming potential of cover crop management

Diversity and density relationships between lebensspuren and tracemaking organisms: a study case from abyssal northwest Pacific

In the deep sea, interactions between benthic fauna and seafloor sediment primarily occur through bioturbation that can be preserved as traces (i.e. lebensspuren). Lebensspuren are common features of deep-sea landscapes and are more abundant than the organisms that produce them (i.e. tracemakers), rendering lebensspuren promising proxies for inferring biodiversity. The density and diversity relationships between lebensspuren and benthic fauna remain unclear, and contradicting correlations have been proposed (i.e. negative, positive, or even null correlations). To approach these variable correlations, lebensspuren and benthic fauna were characterized taxonomically at eight deep-sea stations in the Kuril-Kamchatka Trench area, together with two novel categories: tracemakers (specific epibenthic fauna that produce these traces) and degrading fauna (benthic fauna that can erase lebensspuren). No general correlation (overall study area) was observed between diversities of lebensspuren, tracemakers, degrading fauna, and fauna. However, a diversity correlation was observed at specific stations, showing both negative and positive correlations depending on: (1) the number of unknown tracemakers (especially significant for dwelling lebensspuren); (2) the lebensspuren with multiple origins; and (3) tracemakers that can produce different lebensspuren. Lebensspuren and faunal density were not correlated. However, lebensspuren density was either positively or negatively correlated with tracemaker densities, depending on the lebensspuren morphotypes. A positive correlation was observed for resting lebensspuren (e.g. ophiuroid impressions, Actiniaria circular impressions), while negative correlations were observed for locomotion-feeding lebensspuren (e.g. echinoid trails). In conclusion, lebensspuren diversity may be a good proxy for tracemaker biodiversity when the lebensspuren–tracemaker relationship can be reliable characterized. Lebensspuren–density correlations vary depending on the specific lebensspuren residence time, tracemaker density, and associated behaviour (rate of movement). Overall, we suggest that lebensspuren density and diversity correlations should be studied with tracemakers rather than with general benthic fauna. On a global scale, abiotic (e.g. hydrodynamics, substrate consistency) and other biotic factors (e.g. microbial degradation) may also play an important role.</p

Desarrollo e implementación de un hormigón reforzado con fibras sintéticas para la repavimentación de la Ruta 24 de Uruguay

Los pavimentos de hormigón son estructuras propensas a la fisuración. El uso de fibras aparece como una de las mejores alternativas técnico-económicas para mejorar el comportamiento del hormigón. Una de las aplicaciones del Hormigón Reforzado con Fibras (HRF) es la reparación o refuerzo (“overlays”) de antiguos pavimentos. En la actualidad se dispone de macrofi bras sintéticas que pueden utilizarse en este tipo de aplicaciones en lugar de las tradicionales fi bras de acero. Este trabajo transmite la experiencia adquirida durante la ejecución de la rehabilitación de la Ruta 24 en Uruguay empleando un “whitetopping” delgado (adherido) de HRF. Se describen los resultados obtenidos durante el control de calidad en obra y se discuten los principales desafíos durante la ejecución como el uso de un aditivo reductor de agua de alto rango, el empleo de tecnología de alto rendimiento y el logro de una adecuada adherencia HRF – sustrato asfáltico.Fil: Miguez Pessada, D.. Hormigones Artigas S.A.; UruguayFil: Gonzalez, A. C. Hormigones Artigas S.A.; UruguayFil: Violini, D.. Cementos Avellaneda S.A; ArgentinaFil: Pappalardi, M.. Cementos Avellaneda S.A.; ArgentinaFil: Zerbino, Raul Luis. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ingeniería. Departamento de Construcciones; Argentin

Ancient DNA from Early Human Burials in the Argentine Puna: Insights into Burial Practices and South American Population History

Although the earliest archaeological sites in South America date to the late Pleistocene, little is known about the genetic makeup or mortuary behavior of early hunter-gatherer populations in South America. To help shed light on the burial practices of these hunter-gatherers, as well as the early population history of this region, we extracted ancient DNA from the remains of 13 individuals excavated from early and mid-Holocene archaeological sites in the southern Argentine Puna. These remains are from four locations in the Antofagasta de la Sierra region of northwestern Argentina, and date between 9200 and 3200 YBP. We sequenced 372 base pairs of the first hypervariable region of the mitochondrial DNA to define maternally-inherited genetic lineages, and analyzed a length dimorphism in the amelogenin gene to investigate the sex of each individual. We found that maternally related individuals were sometimes buried together, and several individuals exhibited a mtDNA lineage that is rare in indigenous American populations today. Our results shed light on the early population history of this region and help elucidate the genetic affinities between the prehistoric inhabitants of the Puna and other regions in South America.Fil: Bolnick, Deborah A.. Austin Community College; Estados UnidosFil: Pintar, Elizabeth. Austin Community College; Estados UnidosFil: Martinez, Jorge Gabriel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto Superior de Estudios Sociales. Universidad Nacional de Tucumán. Instituto Superior de Estudios Sociales; ArgentinaFil: Díaz Matallana, Marcela. Pontificia Universidad Javeriana; ColombiaFil: Mata Miguez, Jaime. University of Texas at Austin; Estados Unidos79th Meeting for the Society for American ArchaeologyAustinEstados UnidosSociety for American Archaeolog

Impresión y difusión de trabajos científicos, históricos y literarios raros e inéditos

EI Honorable Consejo Superior de la Universidad Nacional de La Plata, que tengo el honor de presidir, ha resuelto en su sesión de fecha 12 del corriente mes, acogerse a la disposición del articulo 9 de la ley 6286, en cuanto dice que «el Poder Ejecutivo ayudará con los recursos. necesarios a las Universidades Nacionales» ... «para la impresión y difusion de obras y trabajos cientificos, historicos y literarios, con que se resuelva contribuir a la conmemoracion de la independencia y para la adjudicación de premios con tal objeto».Facultad de Ciencias Jurídicas y Sociale