328 research outputs found
On the use of diatomite as antishrinkage additive in the preparation of monolithic carbon aerogels
We have synthesized flexible monolithic carbon aerogels by incorporating diatomite as antishrinkage agent during the sol-gel polycondensation of the precursors. The materials displayed elastic properties and preserved their pristine dimensions upon densification by carbonization even after etching of the diatomite, due to the open pore structure of the siliceous additive in the material’s matrix. The aerogels displayed a well-developed porous structure, confirming that the polymerization of the precursors is not impeded; the effect of the additive was independent of the formulation of the aerogels, as evidenced by the behavior of aerogels with varied composition (molar ratio, pH, N-doping).This work was partially funded by MINECO (grant CTM2014/56770-R, IPT-2011-1450-310000 ADECAR and Feder cofunding). The help of Mr. D.L. García in the preparation of the specimens is greatly appreciated.Peer reviewe
MEXICAN WILD LUPINES AS A SOURCE OF QUINOLIZIDINE ALKALOIDS OF ECONOMIC POTENTIAL
Quinolizidine alkaloids such as lupanine,13-hydroxylupanine, multiflorine, angustifoline and sparteine, which are present inthe species of the genus Lupinus, have beenreported to have biopesticide and pharmacological activities. The aim of this studywas to quantify the content and variationof the individual alkaloids in seeds of L.mexicanus, L. exaltatus, L. montanus andL. stipulatus collected in different states ofMexico. Lupanine was the major (5.05 ±0.37 mg/g) alkaloid found in L. mexicanus,whereas sparteine was the main alkaloidpresent in L. montanus (3.97 ± 0.49 mg/g).Conversely, L. stipulatus contained onlysmall quantities of lupanine and sparteine(0.1 ± 0.002 and 0.04 ± 0.01 mg/g, respectively). Angustifoline was detected only in L.montanus, but in a very low amount (0.048± 0.03). The results of this study indicatethat L. mexicanus and L. montanus can beconsidered as important sources of lupanine and sparteine for their use as natural pesticide or pharmacological agents.Los alcaloides quinolizidinicos lupanina,13-hidroxilupanina, multiflorina, angustifolina y esparteina, presentes en el géneroLupinus poseen actividades bioplagiciday farmacológica. El objetivo del presenteestudio fue cuantificar el contenido y variación de los alcaloides mencionados ensemillas de L. mexicanus, L. exaltatus, L.montanus y L. stipulatus, colectados endiferentes estados de México. La lupaninafue el principal (5.05 ± 0.37mg /g) alcaloideencontrado en L. mexicanus, mientras que laesparteína fue el mayor alcaloide presente en L. montanus (3.97 ± 0.49 mg/g). Sinembargo, en L. stipulatus se encontraron pequeñas cantidades de lupanina y esparteína(0.1 ± 0.002 y 0.04 ± 0.01 mg/g, respectivamente). La angustifolina sólo se detectóen bajos niveles en L. montanus (0.048 ±0.03). Los resultados de este estudio indicanque L. mexicanus y L. montanus pueden serconsiderados como una fuente importantede lupanina y esparteína, los cuales puedenser utilizados como pesticidas o hipoglucé-micos naturales
The Cotton tensor in Riemannian spacetimes
Recently, the study of three-dimensional spaces is becoming of great
interest. In these dimensions the Cotton tensor is prominent as the substitute
for the Weyl tensor. It is conformally invariant and its vanishing is
equivalent to conformal flatness. However, the Cotton tensor arises in the
context of the Bianchi identities and is present in any dimension. We present a
systematic derivation of the Cotton tensor. We perform its irreducible
decomposition and determine its number of independent components for the first
time. Subsequently, we exhibit its characteristic properties and perform a
classification of the Cotton tensor in three dimensions. We investigate some
solutions of Einstein's field equations in three dimensions and of the
topologically massive gravity model of Deser, Jackiw, and Templeton. For each
class examples are given. Finally we investigate the relation between the
Cotton tensor and the energy-momentum in Einstein's theory and derive a
conformally flat perfect fluid solution of Einstein's field equations in three
dimensions.Comment: 27 pages, revtex
EFFECTS OF ICCAT Rec [2016-05] SIZE REGULATION ON THE DISCARDS OF THE SPANISH LONGLINE FISHERY TARGETING SWORDFISH (Xiphias gladius Linnaeus, 1758) IN THE WESTERN MEDITERRANEA
The ICCAT Commission, at its meeting on November 2016, approved a multi-annual recovery
plan for the Mediterranean swordfish starting in 2017 and continuing through 2031 (ICCAT Rec
[2016-05]). Among other provisions, the recovery plan proscribed a minimum landing size (MLS)
of 100 cm (lower-jaw fork length- LJFL), which is 10 cm higher than the previously implemented
(ICCAT Rec [2013-04]). The aim of this study is to assess the effect of the recently implemented
MLS on the swordfish discarding activities by the Spanish surface longline fishery operating in
the western Mediterranean for the period 2015-2017. Our results show that: i) as compared to
the former MLS (ICCAT Rec [2013-04]), a higher percentage of undersized dead fish is now
discarded at sea, with the additional risk that does not be reported and taken into consideration
during the assessment of the stock; ii) the amount of fishing effort (number of hooks) for fulfilling
the allocated quota has increased; iii) the fishing season must be longer to achieve the allocated
quota. Both the increase in fishing effort and the lengthening of the fishing season have an
adverse effect on the economic profitability of the surface longline fleet without achieving the
intended reduction in the fishing mortality exerted on the juvenile fraction of the Mediterranean
swordfish stock
STANDARDIZED CATCH RATES OF ALBACORE (THUNNUS ALALUNGA BONNATERRE, 1788) IN THE SPANISH SURFACE LONGLINE FISHERY IN THE WESTERN MEDITERRANEAN IN THE PERIOD 2009-2019
Standardized relative abundance indices of albacore (Thunnus alalunga Bonnaterre, 1788)
caught by the Spanish surface longline (LLALB) in the western Mediterranean Sea were
estimated for the period 2009-2019. Yearly standardized CPUE were estimated through
Generalized Linear Mixed Effects Models (GLMM) under a negative binomial error
distribution assumption. The main factors in the standardization analysis were year and season
(quarter). The index shows an increasing trend from the beginning of the series (2009) to a
maximum in 2011; following a decrease up to 2013, and a relatively stable trend fluctuating
around a level three and a half times lower compared to the maximum abundance for the period
2013-2019.En prens
Standardized catch rates for Mediterranean swordfish (Xiphias gladius Linnaeus, 1758) from the Spanish longline fishery. 1988-2017.
Standardized relative abundance indices for swordfish (Xiphias gladius Linnaeus, 1758) caught
by the Spanish surface longline in the western Mediterranean Sea were estimated for the period
1988-2017. Standardized CPUEs were estimated through a General Linear Mixed Modeling
(GLMM) approach under a negative binomial (NB) error distribution assumption. The main
factors in the standardization analysis were fishing area and time of the year (quarter). The
standardized index showed notable annual fluctuations without any definite trend for the period
under study
Noncommutative Quantum Cosmology
We propose a model for noncommutative quantum cosmology by means of a
deformation of minisuperspace. For the Kantowski-Sachs metric we are able to
find the exact wave function. We construct wave packets and show that new
quantum states that ``compete'' to be the most probable state appear, in clear
contrast with the commutative case. A tunneling process could be possible among
these states.Comment: 5 pages, 5 figures, revtex4 file, major style changes, to be
published in PR
Geology of La Reforma caldera complex, Baja California, Mexico
A new geological map at 1:50,000 scale of La Reforma Caldera Complex has been produced applying modern survey methodologies to volcanic areas. This map aims to represent a reliable and objective tool to understand the geological evolution of the region. La Reforma Caldera Complex is a Pleistocene nested caldera located in the central part of the Baja California peninsula, Mexico. The twelve formations defined within the Quaternary volcanic record were grouped into three phases (pre-caldera, caldera, and post-caldera). The pre-caldera phase (>1.35 Ma) is characterized by scattered eruptions, mostly occurred in submarine environment. The caldera phase (1.35–0.96 Ma) groups several distinct explosive and effusive eruptions that formed the present-day caldera depression. The post caldera phase includes scattered effusive eruptions (ended at 0.28 Ma) and resurgence, characterized by several hundred meters of uplift of the central block within the caldera depression
The dynamic use of EGFR mutation analysis in cell-free DNA as a follow-up biomarker during different treatment lines in non-small-cell lung cancer patients
Epidermal growth factor receptor (EGFR) mutational testing in advanced non-small-cell lung cancer (NSCLC) is usually performed
in tumor tissue, although cfDNA (cell-free DNA) could be an alternative. We evaluated EGFR mutations in cfDNA as a
complementary tool in patients, who had already known EGFR mutations in tumor tissue and were treated with either
EGFR-tyrosine kinase inhibitors (TKIs) or chemotherapy. We obtained plasma samples from 21 advanced NSCLC patients with
known EGFR tumor mutations, before and during therapy with EGFR-TKIs and/or chemotherapy. cfDNA was isolated and
EGFR mutations were analyzed with the multiple targeted cobas EGFR Mutation Test v2. EGFR mutations were detected at
baseline in cfDNA from 57% of patients. The semiquantitative index (SQI) significantly decreased from the baseline
(median = 11, IQR = 9 5-13) to the best response (median = 0, IQR = 0-0, p < 0 01), followed by a significant increase at
progression (median = 11, IQR = 11-15, p < 0 01) in patients treated with either EGFR-TKIs or chemotherapy. The SQI obtained
with the cobas EGFR Mutation Test v2 did not correlate with the concentration in copies/mL determined by droplet digital
PCR. Resistance mutation p.T790M was observed at progression in patients with either type of treatment. In conclusion, cfDNA
multiple targeted EGFR mutation analysis is useful for treatment monitoring in tissue of EGFR-positive NSCLC patients
independently of the drug received
Cryo-EM and single-particle analysis with Scipion
Cryo-electron microscopy has become one of the most important tools in biological research to reveal the structural information of macromolecules at near-atomic resolution. In single-particle analysis, the vitrified sample is imaged by an electron beam and the detectors at the end of the microscope column produce movies of that sample. These movies contain thousands of images of identical particles in random orientations. The data need to go through an image processing workflow with multiple steps to obtain the final 3D reconstructed volume. The goal of the image processing workflow is to identify the acquisition parameters to be able to reconstruct the specimen under study. Scipion provides all the tools to create this workflow using several image processing packages in an integrative framework, also allowing the traceability of the results. In this article the whole image processing workflow in Scipion is presented and discussed with data coming from a real test case, giving all the details necessary to go from the movies obtained by the microscope to a high resolution final 3D reconstruction. Also, the power of using consensus tools that allow combining methods, and confirming results along every step of the workflow, improving the accuracy of the obtained results, is discussed
- …