S wave velocity structure below central Mexico using high-resolution surface wave tomography

Shear wave velocity of the crust below central Mexico is estimated using surface wave dispersion measurements from regional earthquakes recorded on a dense, 500 km long linear seismic network. Vertical components of regional records from 90 well-located earthquakes were used to compute Rayleigh-wave group-velocity dispersion curves. A tomographic inversion, with high resolution in a zone close to the array, obtained for periods between 5 and 50 s reveals significant differences relative to a reference model, especially at larger periods (>30 s). A 2-D S wave velocity model is obtained from the inversion of local dispersion curves that were reconstructed from the tomographic solutions. The results show large differences, especially in the lower crust, among back-arc, volcanic arc, and fore-arc regions; they also show a well-resolved low-velocity zone just below the active part of the Trans Mexican Volcanic Belt (TMVB) suggesting the presence of a mantle wedge. Low densities in the back arc, inferred from the low shear wave velocities, can provide isostatic support for the TMVB

A comparative analysis of the observed white dwarf cooling sequence from globular clusters

We report our study of features at the observed red end of the white dwarf cooling sequences for three Galactic globular clusters: NGC\,6397, 47\,Tucanae and M\,4. We use deep colour-magnitude diagrams constructed from archival Hubble Space Telescope (ACS) to systematically investigate the blue turn at faint magnitudes and the age determinations for each cluster. We find that the age difference between NGC\,6397 and 47\,Tuc is 1.98$^{+0.44}_{-0.26}$\,Gyr, consistent with the picture that metal-rich halo clusters were formed later than metal-poor halo clusters. We self-consistently include the effect of metallicity on the progenitor age and the initial-to-final mass relation. In contrast with previous investigations that invoked a single white dwarf mass for each cluster, the data shows a spread of white dwarf masses that better reproduce the shape and location of the blue turn. This effect alone, however, does not completely reproduce the observational data - the blue turn retains some mystery. In this context, we discuss several other potential problems in the models. These include possible partial mixing of H and He in the atmosphere of white dwarf stars, the lack of a good physical description of the collision-induced absorption process and uncertainties in the opacities at low temperatures. The latter are already known to be significant in the description of the cool main sequence. Additionally, we find that the present day local mass function of NGC\,6397 is consistent with a top-heavy type, while 47\,Tuc presents a bottom-heavy profile.Comment: Accepted for publication in MNRAS (16 pages, 19 figures

Stability of biofortified cassava fried chips.

The purpose of this study was to survey information on the effect of the type of package and packaging system of the product to preserve the nutritional and sensorial quality of biofortified fried cassava chips

Efeito de sistemas de embalagens na estabilidade da farinha de raspa de mandioca biofortificada.

Produtos de mandioca biofortificados com alto teor de carotenóides são fontes de vitamina A, mas devem ser acondicionado em sistemas de embalagem que retardem a degradação dos carotenóides para prolongar a vida de prateleira

Estudo da taxa de degradação de vitamina C em alguns sucos de frutas.

A vitamina C é uma vitamina de extrema importância para o ser humano não somente por sua atividade antiescorbútica, mas também pelas inúmeras atividades fisiológicas e antioxidantes que exerce. Este trabalho visa desmistificar o senso comum estabelecido de que a vitamina C é destruída pouco depois que um suco de frutas é preparado. Para isto, um breve estudo utilizando alguns sucos de frutas foi realizado. Tal estudo consistiu de extrações da vitamina C dos sucos preparados inicialmente e também após 2, 4 e 6 horas de exposição destes à temperatura ambiente. Os resultados obtidos mostraram que após seis horas o suco que obteve a maior perda de vitamina C foi o suco de laranja, mas tratou-se de perda inferior a 22% do teor inicial

A Source Study of the Bhuj, India, Earthquake of 26 January 2001 (M_w 7.6)

We study the source time function (STF) and radiated seismic energy (E_R) of the M_w 7.6 Bhuj earthquake using the empirical Green's function (EGF) technique. Our estimations of the STF and E_R are based on teleseismic P waves and regional seismograms, respectively. We find that the STFs as a function of azimuth have a similar shape and nearly constant duration of 18 sec. This suggests that the rupture propagation was essentially radial. The STFs show a sharp rise in the first 6 sec. The E_R estimated from the EGF technique is 2.1 × 10^(23) erg. We find that E_R's computed from integration of corrected velocity-squared spectra of teleseismic P waves and regional seismograms are in excellent agreement with the ER obtained from the EGF technique. Since the seismic moment, M_0, is 3.4 × 10^(27) dyne cm, we obtain E_R/M_0 = 6.2 × 10^(-5). The radiation efficiency, η_R, during the Bhuj earthquake was low, about 0.23. The sharp rise of the STFs and η_R = 0.23 can be explained by Sato and Hirasawa's (1973) quasi-dynamic, circular source model with an effective stress of ∼ 300 bar and the ratio of rupture to shear-wave velocity, V_R/β, of ∼ 0.5. The corresponding estimate of slip velocity at the center of the fault is 156 cm/sec. V_R/β ∼ 0.5 is in reasonable agreement with the duration of the STF and the reported dimension of the aftershocks, as well as with the results of inversion of teleseismic body waves. The observations may also be explained by a frictional sliding model, with gradual frictional stress drop and significant dissipation of energy on the fault plane. This model requires an average dynamic stress drop of about 120 bar and V_R/β ∼ 0.7 to explain both the rapid rise in the first 6 sec of the STFs and, along with a static stress drop of 200 bar, the observed E_R/M_0. High static stress drop is a common feature of most crustal earthquakes in stable continental regions. An examination of the available data, however, does not suggest that most of them also have relatively low radiation efficiency

Subproductos del cacao (Theobroma cacao) como alternativa para la mejora de la dieta balanceada en rumiantes

Cocoa production is estimated at 4.7 million tons per year, of which 90% are waste residues, such as cocoa husks (CC). These agricultural by-products are a source of nutritional compounds of interest to the ruminant sector. Studies carried out on this matter have shown that it has a high percentage of proteins, fiber, phenols, among others, which give it nutraceutical properties. The fiber present in CC has the potential to absorb oils and cholesterol, thus reducing its bioavailability during digestion. Therefore, the objective of this research was to describe and analyze the nutritional properties of cocoa by-products in the induction of a balanced diet for ruminant animals. The analysis was performed by searching the literature review (Scopus, Scielo) during the months of April and May 2022, the guidelines of the PRISMA statement were followed and to establish the search string, the Boléan operators were used. Current evidence suggests the use of cocoa by-products as an alternative for the improvement of the balanced diet in ruminants (under relevant parameters), as a non-conventional alternative raw material in diets for the ruminant sector for its contribution in protein and fiber that helps fattening without detrimental effects on milk production performanceSe estima que la producción de cacao es de 4.7 millones de toneladas por año, de los cuales el 90% son residuos de desecho, tal como la cascara o cascarilla del cacao (CC). Estos subproductos agrícolas son fuente de compuestos nutritivos de interés para el sector de rumiantes. Los estudios realizados en esta materia han demostrado que tiene un alto porcentaje de proteínas, fibra, fenoles entre otros, que le otorgan propiedades nutraceúticas. La fibra presente en la CC tiene el potencial de absorción de aceites y colesterol, reduciendo de esta forma su biodisponibilidad durante la digestión. Por tanto, el objetivo de esta investigación fue describir y analizar las propiedades nutritivas de los subproductos del cacao en la inducción de una dieta balanceada para animales rumiantes. El análisis se realizó mediante la búsqueda de la revisión bibliográfica (Scopus, Scielo) durante los meses de abril y mayo del 2022, se siguió las directrices de la declaración PRISMA y para establecer la cadena de búsqueda se utilizó los operadores boléanos. La evidencia actual sugiere la utilización de los subproductos del cacao como alternativa para la mejora de la dieta balanceada en rumiantes (bajo parámetros pertinentes), como materia prima alternativa no convencional en dietas destinados al sector de rumiantes por su aporte en proteínas y fibra que ayuda al engorde sin efectos perjudícales al rendimiento de producción de leche

Asperities and barriers on the seismogenic zone in North Chile: state-of-the-art after the 2007 Mw 7.7 Tocopilla earthquake inferred by GPS and InSAR data

The Mw 7.7 2007 November 14 earthquake had an epicentre located close to the city of Tocopilla, at the southern end of a known seismic gap in North Chile. Through modelling of Global Positioning System (GPS) and radar interferometry (InSAR) data, we show that this event ruptured the deeper part of the seismogenic interface (30–50 km) and did not reach the surface. The earthquake initiated at the hypocentre and was arrested ~150 km south, beneath the Mejillones Peninsula, an area already identified as an important structural barrier between two segments of the Peru–Chile subduction zone. Our preferred models for the Tocopilla main shock show slip concentrated in two main asperities, consistent with previous inversions of seismological data. Slip appears to have propagated towards relatively shallow depths at its southern extremity, under the Mejillones Peninsula. Our analysis of post-seismic deformation suggests that small but still significant post-seismic slip occurred within the first 10 d after the main shock, and that it was mostly concentrated at the southern end of the rupture. The post-seismic deformation occurring in this period represents ~12–19 per cent of the coseismic deformation, of which ~30–55 per cent has been released aseismically. Post-seismic slip appears to concentrate within regions that exhibit low coseismic slip, suggesting that the afterslip distribution during the first month of the post-seismic interval complements the coseismic slip. The 2007 Tocopilla earthquake released only ~2.5 per cent of the moment deficit accumulated on the interface during the past 130 yr and may be regarded as a possible precursor of a larger subduction earthquake rupturing partially or completely the 500-km-long North Chile seismic gap