507 research outputs found

    High Resolution Attenuation Images From Active Seismic Data: The Case Study of Solfatara Volcano (Southern Italy)

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    <p>The anelastic attenuation of rocks strongly depends on the contained fluid physical state and saturation. Furthermore, it is more sensitive than elastic parameters to changes in the physical state of materials. In a geologically complex  volcanic context, where fluids play a very important role, anelastic imaging of the subsoil is therefore a very powerful tool for a better understanding of its dynamics.</p><p>In this study we present a robust workflow aimed at retrieve accurate 1-D and 3-D anelastic models from the processing of active seismic data, in terms of lateral and depth variations of P-wave quality factors Q<sub>P</sub>. This methodology has been applied to data collected during a high resolution active seismic experiment in a very small-scale volcanic volume, the Solfatara crater, within Campi Flegri caldera, Southern Italy. The presented methodology is developed in three distinct steps: 1) the active seismic data have been properly processed and analyzed for measuring the t* attenuation parameter for all possible source-receivers couples. First, the source contribution has been removed by cross-correlating the recorded signal with the sweep function of the Vibroseis, which was the adopted active seismic source. Then, the spectral decay method has been applied in order to compute the t* values. 2) A reference 1-D attenuation model has been retrieved by means of a grid search procedure aiming at finding the 1-D Qp structure that minimizes the residual between the average observed t* and the theoretical t* distributions. The obtained starting reference model allowed to build a preliminary map of t* residuals through which the retrieved t* dataset has been validated. 3) The 15,296 t* measurements have been inverted by means of a linearized, perturbative approach, in a 160 x 160 x 45 m<sup>3 </sup>tomographic grid.</p><p>The retrieved 3-D attenuation model describes the first 30 m depths of Solfatara volcano as composed of very high attenuating materials, with Qp values ranging between 5 and 40. The very low Qp values, correlated with low Vp values retrieved by a previous tomographic work carried out in the area, indicate the low consolidation degree of very superficial volcanic materials of Solfatara volcano. Finally, in the NE part of the crater, lower attenuating bodies have been imaged: it is a further hint for characterizing this area of the volcano as the shallow release of the CO<sub>2 </sub>plume through the main fumaroles of the crater.</p&gt

    Inorganic polyphosphate regulates AMPA and NMDA receptors and protects against glutamate excitotoxicity via activation of P2Y receptors

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    Glutamate is one of the most important neurotransmitters in the process of signal transduction in the central nervous system. Excessive amounts of this neurotransmitter lead to glutamate excitotoxicity which is accountable for neuronal death in acute neurological disorders including stroke, trauma, and in neurodegenerative diseases. Inorganic polyphosphate (PolyP) plays multiple roles in the mammalian brain, including function as a calcium-dependent gliotransmitter mediating communication between astrocytes, while its role in the regulation of neuronal activity is unknown. Here we studied the effect of polyP on glutamate-induced calcium signal in primary rat neurons in both physiological and pathological conditions. We found that pre-incubation of primary neurons with polyP reduced glutamate- and AMPA- but not the NMDA-induced calcium signal. However, in rat hippocampal acute slices polyP reduced ion flux through NMDA and AMPA receptors in native neurons. The effect of polyP on glutamate and specifically on the AMPA receptors was dependent on the presence of P2Y1 but not of P2X receptor inhibitors and also could be mimicked by P2Y1 agonist 2MeSADP. Pre-incubation of cortical neurons with polyP significantly reduced the initial calcium peak as well as the number of neurons with delayed calcium deregulation in response to high concentrations of glutamate and resulted in protection of neurons against glutamate-induced cell death. As a result, activation of P2Y1 receptors by polyP reduced calcium signal acting through AMPA receptors, thus protecting neurons against glutamate excitotoxicity by reduction of the calcium overload and restoration of mitochondrial function.Significance StatementOne of the oldest polymers in the evolution of living matter is the inorganic polyphosphate. It is shown to play a role of gliotransmitter in the brain; however, the role of polyphosphate in neuronal signalling is not clear. Here we demonstrate that inorganic polyphosphate is able to reduce calcium signal, induced by physiological or high concentrations of glutamate. The effect of polyphosphate on glutamate-induced calcium signal in neurons is due to the effect of this polymer on the AMPA receptors.The effect of polyP on glutamate- and AMPA-induced calcium signal is dependent on P2Y receptor antagonist. The ability of polyphosphate to restrict glutamate-induced calcium signal lies in the basis of its protection of neurons against glutamate excitotoxicity

    Clinical pharmacogenetics of methotrexate

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    It is well known that interindividual variability can affect the response to many drugs in relation to age, gender, diet, and organ function. Pharmacogenomic studies have also documented that genetic polymorphisms can exert clinically significant effects in terms of drug resistance, efficacy and toxicity by modifying the expression of critical gene products (drug-metabolizing enzymes, transporters, and target molecules) as well as pharmacokinetic and pharmacodynamic parameters. A growing body of in vitro and clinical evidence suggests that common polymorphisms in the folate gene pathway are associated with an altered response to methotrexate (MTX) in patients with malignancy and autoimmune disease. Such polymorphisms may also induce significant MTX toxicity requiring expensive monitoring and treatment. Although the available data are not conclusive, they suggest that in the future MTX pharmacogenetics could play a key role in clinical practice by improving and tailoring treatment. This review describes the genetic polymorphisms that significantly influence MTX resistance, efficacy, and toxicity

    LICIACube Mission: The Fastest Fly-By Ever Done by a CubeSat

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    As SmallSats are gathering an ever-increasing importance for all types of space missions, they are asked more often to operate in harshest environments and to complete the most complex tasks. One of these demanding technical challenges arises in the frame of the planetary defense. Space missions towards asteroids have garnered the due attention in recent years and, in this regard, NASA has developed the Double Asteroid Redirection Test (DART) mission, in which the Italy will lend its contribution. While DART acts as a kinetic impactor deflecting the orbit of the asteroid Dimorphos, the moon of the targeted binary system Didymos, the Light Italian CubeSat for Imaging of Asteroid (LICIACube) collects and gathers valuable images of the effect of the DART impact on the rocky body. LICIACube will allow to study the structure and evolution of the ejecta plume resulting from the impact, and to model both impacted and non-impacted sides of Dimorphos. LICIACube is an Italian Space Agency (ASI) project, whose design, integration and testing have been assigned to the aerospace company Argotec. The scientific team is enriched by University of Bologna team, supporting the orbit determination and the satellite navigation, Polytechnic of Milan, for mission analysis support and optimization and INAF (National Institute of Astrophysics), which provides support in the scientific operations of the satellite, instrument calibrations and data exploitation. This work focuses on the fly-by of LICIACube which will be accomplished using the imaging capabilities provided by theArgotecHAWK-6 platform and by the autonomous navigation system. In order to acquire high-resolution images, LICIACube approaches Dimorphos at a relative distance of 55km. The very close fly-by, the high relative velocity of ∼7 km/s with respect to the asteroid and the need to keep LICIACube camera pointed at Dimorphos make the mission very challenging. In addition, since the binary asteroid system is ∼10 million kilometers away from Earth, the fly-by has to be performed with no real time commanding. As a result, LICIACube shall be able to autonomously analyze all information from its sensors to track the asteroid. The evaluation and subsequent solutions to this problem are presented in this paper, as well as a unit-level description of the parts included in the autonomous navigation system. Finally, an overview of the verification of both unit-level and system-level strategies is outlined

    Loss of nuclear p27kip1 and α-dystroglycan is a frequent event and is a strong predictor of poor outcome in renal cell carcinoma

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    Expression levels of p27kip1, a negative regulator of the G1 phase of the cell cycle, and 8-hydroxydeoxyguanosine (8-OHdG), a marker of oxidative DNA damage, were assessed by immunostaining in a series of renal cell carcinomas (RCCs) and their prognostic significance was evaluated. Expression of p27kip1 as well as of the α-subunit of the dystroglycan (DG) complex, previously reported to be altered in RCC, was also evaluated by western blot analysis. Nuclear expression of p27kip1 was reduced in a significant fraction of tumors and low p27kip1 staining correlated with higher tumor grade (P < 0.01). Recurrence and death from clear cell RCCs were significantly more frequent in p27kip1-low expressing tumors and Kaplan–Meier curves showed a significant separation between high vs low expressor groups for both disease-free (P = 0.011) and overall (P = 0.002) survival. Low nuclear expression of p27kip1 as well as loss of α-DG were confirmed to be independent prognostic parameters at a multivariate analysis and the simultaneous loss of both molecules defined a "high-risk" group of patients with increased risk of recurrence (RR = 28.7; P = 0.01) and death (RR = 12.9; P = 0.03). No significant correlation with clinical or pathological parameters was found for 8-OHdG staining. Western blot analyses suggested a post-translational mechanism for the loss of α-DG expression and demonstrated that cytoplasmic dislocation of the protein contributes to the loss of active nuclear p27kip1. Loss of nuclear p27kip1 is a frequent event in human RCCs and is a powerful predictor of poor outcome which, in combination with low DG expression, could help to identify high-risk patients with clear cell RCC. (Cancer Sci 2010; 00: 000–000

    Geometry and evolution of a fault-controlled Quaternary basin by means of TDEM and single-station ambient vibration surveys: The example of the 2009 L'Aquila earthquake area, central Italy

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    We applied a joint survey approach integrating time domain electromagnetic soundings and single-station ambient vibration surveys in the Middle Aterno Valley (MAV), an intermontane basin in central Italy and the locus of the 2009 L’Aquila earthquake. By imaging the buried interface between the infilling deposits and the top of the pre-Quaternary bedrock, we reveal the 3-D basin geometry and gain insights into the long-term basin evolution. We reconstruct a complex subsurface architecture, characterized by three main depocenters separated by thresholds. Basin infill thickness varies from ~200–300m in the north to more than 450m to the southeast. Our subsurface model indicates a strong structural control on the architecture of the basin and highlights that the MAV experienced considerable modifications in its configuration over time. The buried shape of the MAV suggests a recent and still ongoing predominant tectonic control by the NW-SE trending Paganica-San Demetrio Fault System (PSDFS), which crosscuts older ~ENE and NNE trending extensional faults. Furthermore, we postulate that the present-day arrangement of the PSDFS is the result of the linkage of two previously isolated fault segments. We provide constraints on the location of the southeastern boundary of the PSDFS, defining an overall ~19 km long fault system characterized by a considerable seismogenetic potential and a maximum expected magnitude larger than M6.5. This study emphasizes the benefit of combining two easily deployable geophysical methods for reconstructing the 3-D geometry of a tectonically controlled basin. Our joint approach provided us with a consistent match between these two independent estimations of the basin substratum depth within 15%.Published2236–22597T. Struttura della Terra e geodinamica2TR. Ricostruzione e modellazione della struttura crostaleJCR Journa
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