And yet another method for the identification of modal constants in experimental modal analysis

Modal Identification from Frequency Response Functions (FRFs) is a chapter of Experimental Modal Analysis (EMA) that many would consider being closed in a book and covered in dust. Yet, in a previous paper from the same authors, a new approach to determine the modal damping factors from FRFs was proposed. Contrary to other modal identification methods which are based on the dynamic motion governing equations, the method used as a starting point the dissipated energy per cycle of vibration. For lightly damped systems with conveniently spaced modes, it produced quite accurate results, especially when compared to the method of the inverse. The method used a plot of the sine of the phase of the receptance against its amplitude, whereby damping was determined from the slope. In this paper, it will be shown that this plot has other special properties, whereby the real and imaginary parts of the modal constants can be determined from the plot through numerical extrapolation

Improvement of three nucleic acid isolation protocols for an overall diagnosis of viruses on six vegetative propagated plants

Biological Resources Center (BRCs) must be able to guarantee the sanitary status of the resources they distribute, in order to prevent the spread or emergence of diseases. However, BRCs' vegetatively propagated crops do not benefit from the partial sanitation occurring through a seed cycle. This is particularly a problem for viral diseases, which have an overall high prevalence in vegetatively propagated crops. Variously effective sanitation methods exist for recovering virus-free plants but their successful implementation depends on on the availability of sensitive, polyvalent and reliable diagnosis tests for all relevant virus species. The main objective of the SafePGR project is to improve the knowledge of the diversity of viruses infecting the vegetatively propagated crops addressed by the partners' BRCs (Universidad do Açores, Universidad da Madeira, INRA-CIRAD Guadeloupe and CIRAD La Réunion). Among the various issues addressed in achieving the goals of the SafePGR project, we need to develop new tools for an overall diagnosis of viruses. Thus, recent metagenomics methods associated with high-throughput sequencing will be tested. For this purpose, we started to develop and adapt three different nucleic acids extractions on six plants species: banana, garlic, sugarcane, sweet potato, vanilla and yam. First, we succeeded to extract small RNAs using Trizol or phenol:chloroform methods on these six species. Then, we have developed a protocol to semi-purify viral particles. The third protocol consisted in an enrichment of double-stranded RNAs. The quality and quantity of extracted nucleic acid varied among plant species. Overall, the extracted RNAs from garlic, sugarcane, sweet potato and vanilla were fulfilling criteria of quality and quantity for being used for metagenomic approaches whereas the ones from banana and yam were not adequate. These preliminary results tend to indicate that it would be probably difficult to develop a universal nucleic acid isolation method that could be routinely used by our partners' BRCs. (Texte intégral

Population expansion in the North African Late Pleistocene signalled by mitochondrial DNA haplogroup U6

Background <br/> The archaeology of North Africa remains enigmatic, with questions of population continuity versus discontinuity taking centre-stage. Debates have focused on population transitions between the bearers of the Middle Palaeolithic Aterian industry and the later Upper Palaeolithic populations of the Maghreb, as well as between the late Pleistocene and Holocene. <br/> Results Improved resolution of the mitochondrial DNA (mtDNA) haplogroup U6 phylogeny, by the screening of 39 new complete sequences, has enabled us to infer a signal of moderate population expansion using Bayesian coalescent methods. To ascertain the time for this expansion, we applied both a mutation rate accounting for purifying selection and one with an internal calibration based on four approximate archaeological dates: the settlement of the Canary Islands, the settlement of Sardinia and its internal population re-expansion, and the split between haplogroups U5 and U6 around the time of the first modern human settlement of the Near East. <br/> Conclusions <br/> A Bayesian skyline plot placed the main expansion in the time frame of the Late Pleistocene, around 20 ka, and spatial smoothing techniques suggested that the most probable geographic region for this demographic event was to the west of North Africa. A comparison with U6's European sister clade, U5, revealed a stronger population expansion at around this time in Europe. Also in contrast with U5, a weak signal of a recent population expansion in the last 5,000 years was observed in North Africa, pointing to a moderate impact of the late Neolithic on the local population size of the southern Mediterranean coast

On the use of controlled radiation pressure to send a satellite to a graveyard orbit

A very important topic in modern astrodynamics is the removal of satellites from their orbits, after the end of their missions. In this work, we propose the use of the solar radiation pressure to change the orbital energy of a satellite, to remove it from the operational region to a graveyard orbit. A mechanism for changing the area-to-mass ratio of the satellite and/or its reflectivity coefficient is used to accomplish this task. We derive an analytical model to find the maximum eccen- tricity achieved during the removal trajectory, for different initial conditions for the argument of perigee and the longitude of the ascending node. After that, the best trajectories, i.e., trajectories with low eccentricity, are integrated using a numerical model. These low eccentricity trajectories are important because satellites with disposal orbits with low eccentricity pose a lower risk of crossing the operational region during the de-orbiting.Un tema importante en la astrodinámica moderna es la remoción de satélites de sus órbitas al finalizar sus misiones. En este trabajo proponemos utilizar la presión de la radiación solar para modificar la energía orbital del satélite, y así alejarlo de la región operacional y enviarlo a una órbita “en el cementerio”. Para este propósito, se propone un mecanismo para cambiar la razón área-masa y/o la reflectividad del satélite. Obtenemos un modelo analítico para encontrar la máxima excentricidad alcanzada durante la trayectoria de remoción, para diferentes valores iniciales del argumento del perigeo y de la longitud del nodo ascendente. A continuación, las mejores trayectorias, esto es, las de menor excenticidad, se integran numéricamente. Estas trayectorias de baja excentricidad son importantes pues los satélites con ´orbitas de desecho de baja excentricidad tienen un menor riesgo de cruzar las regiones operacionales durante su eliminación.The author is thankful for the grants # 406841/2016-0 and 301338/2016-7 from the National Council for Scientific and Technological Development (CNPq); and grants # 2014/22295-5, 2011/08171-3, 2016/14665-2 and 2016/07248-6 from São Paulo Research Foundation (FAPESP).info:eu-repo/semantics/publishedVersio

Hydrogen-Helium Mixtures at High Pressure

The properties of hydrogen-helium mixtures at high pressure are crucial to address important questions about the interior of Giant planets e.g. whether Jupiter has a rocky core and did it emerge via core accretion? Using path integral Monte Carlo simulations, we study the properties of these mixtures as a function of temperature, density and composition. The equation of state is calculated and compared to chemical models. We probe the accuracy of the ideal mixing approximation commonly used in such models. Finally, we discuss the structure of the liquid in terms of pair correlation functions.Comment: Proceedings article of the 5th Conference on Cryocrystals and Quantum Crystals in Wroclaw, Poland, submitted to J. Low. Temp. Phys. (2004

A Monte-Carlo study of the AdS/CFT correspondence: an exploration of quantum gravity effects

In this paper we study the AdS/CFT correspondence for N=4 SYM with gauge group U(N), compactified on S^3 in four dimensions using Monte-Carlo techniques. The simulation is based on a particular reduction of degrees of freedom to commuting matrices of constant fields, and in particular, we can write the wave functions of these degrees of freedom exactly. The square of the wave function is equivalent to a probability density for a Boltzman gas of interacting particles in six dimensions. From the simulation we can extract the density particle distribution for each wave function, and this distribution can be interpreted as a special geometric locus in the gravitational dual. Studying the wave functions associated to half-BPS giant gravitons, we are able to show that the matrix model can measure the Planck scale directly. We also show that the output of our simulation seems to match various theoretical expectations in the large N limit and that it captures 1/N effects as statistical fluctuations of the Boltzman gas with the expected scaling. Our results suggest that this is a very promising approach to explore quantum corrections and effects in gravitational physics on AdS spaces.Comment: 40 pages, 7 figures, uses JHEP. v2: references adde

Regional differences of testicular artery blood flow in post pubertal and pre-pubertal dogs

Background Measurement of testicular artery blood flow is used in several species to evaluate reproductive function and testicular and scrotal pathology. In dogs there are inconsistent reports about normal flow in post-pubertal dogs and no information concerning pre-pubertal dogs. The aim of this study was to describe regional differences in testicular artery blood flow in clinically normal post-pubertal and pre-pubertal dogs with no history of reproductive tract disease. Results The post-pubertal dogs produced normal ejaculates throughout the study. In all dogs the three different regions of the artery were imaged and monophasic flow with an obvious systolic peak and flow throughout diastole was observed on every occasion. The highest peak systolic velocity (PSV) and end diastolic velocity (EDV) were measured within the distal supra-testicular artery and marginal artery whilst the lowest PSV and EDV were measured within the intra-testicular arteries. Flow measurements were not different between left and right testes and were consistent between dogs on different examination days. Calculated resistance index (RI) and pulsatility index (PI) were lowest in the intra-testicular arteries. The pre-pubertal dogs had significantly smaller testes than the post-pubertal dogs (p < 0.05) and were unable to ejaculate during the study. The three different artery regions were imaged at every examination time point, and flow profiles had a similar appearance to those of the post-pubertal dogs. PSV, EDV, RI and PI showed a similar trend to the post-pubertal dogs in that values were lowest in the intra-testicular arteries. Notably, values of PSV, EDV, RI and PI were significantly lower (p < 0.05) in pre-pubertal dogs compared with post-pubertal dogs. Conclusions This study demonstrated important regional and pubertal differences in testicular artery blood flow of dogs, and form the basis for establishing baseline reference values that may be employed for the purposes of clinical diagnosis

Observational constraint on generalized Chaplygin gas model

We investigate observational constraints on the generalized Chaplygin gas (GCG) model as the unification of dark matter and dark energy from the latest observational data: the Union SNe Ia data, the observational Hubble data, the SDSS baryon acoustic peak and the five-year WMAP shift parameter. It is obtained that the best fit values of the GCG model parameters with their confidence level are $A_{s}=0.73^{+0.06}_{-0.06}$ ($1\sigma$) $^{+0.09}_{-0.09}$ $(2\sigma)$, $\alpha=-0.09^{+0.15}_{-0.12}$ ($1\sigma$) $^{+0.26}_{-0.19}$ $(2\sigma)$. Furthermore in this model, we can see that the evolution of equation of state (EOS) for dark energy is similar to quiessence, and its current best-fit value is $w_{0de}=-0.96$ with the $1\sigma$ confidence level $-0.91\geq w_{0de}\geq-1.00$.Comment: 9 pages, 5 figure

New molecular approaches in adipogenesis regulation: The connexin 43 role

Indexación: Scopus; Redalyc.La prevalencia de la obesidad a nivel mundial se ha incrementado rápidamente durante los últimos años debido principalmente a los cambios en el estilo de vida de la población con un aumento significativo en el consumo de energía y disminución de los niveles de actividad física. Es por esto que la comunidad científica está interesada en comprender de forma más profunda los mecanismos que regulan la fisiopatología de la obesidad. Dentro de los diferentes blancos de estudio se encuentra la adipogénesis, cuyo entendimiento es fundamental para comprender el desarrollo de la obesidad y las patologías asociadas a esta. Recientemente ha surgido importantes evidencias que involucran a la proteína de canales de “Gap Junction” conexina 43 (Cx43) en la regulación de los procesos relacionados con adipogénesis, cuyo papel es básicamente anti-adipogénico, sin embargo, nuevas funciones de Cx43 en la regulación de la formación del tejido adiposo siguen descubriéndose.The global prevalence of obesity has been increased rapidly over the past few years mainly due to changes in the lifestyle of the population with a significant increase in energy consumption and decreased levels of physical activity. As a result, the scientific community is interested in a deeper understanding of the mechanisms that regulate the pathophysiology of obesity. In this context, adipogenesis process is an important target of study to understand the obesity and associated pathologies. Recently has been emerged important evidence that involve gap junction channel protein connexin 43 (Cx43) in the regulation of processes related to adipogenesis, whose role is fundamentally anti-adipogenic. However, new functions of Cx43 in the regulation of adipose tissue function also continued to emerge.http://www.redalyc.org/articulo.oa?id=5594990800