83 research outputs found
RELACIÓN ENTRE MATERIALES GEOLÓGICOS Y LAS PROPIEDADES FÍSICAS Y QUÍMICAS DE LOS SUELOS.
El presente estudio fue realizado en la zona de influencia de la cordillera del Ybytyruzu en el Departamento de Guaira, localidad ubicada al sureste de Asunción. El objetivo principal de la presente investigación fue identificar los principales efectos que producen la roca basáltica y la roca arenisca sobre las propiedades físicas y químicas de los suelos formados a partir de ellas. La metodología aplicada en este estudio consistió en trabajos de campo y análisis laboratorial de las muestras obtenidas.Los resultados indican marcada diferencia, tanto en las propiedades físicas y químicas, entre los suelos originados de rocas sedimentarias - arenisca y suelos originados de rocas ígneas - basalto. La textura gruesa es dominante para suelos originados de arenisca, mientras que la textura fina predomina en suelos originados de basalto. Utilizando el método del tacto también se identificó importantes diferencias en la plasticidad y pegajosidad de suelos originados de rocas sedimentarias – areniscas fue muy baja en relación a suelos originados de roca basáltica. La estructuración también fue más débil en suelos de textura gruesa en comparación a suelos de textura fina. En cuanto al tamaño de poros se puede mencionar que los suelos de textura gruesa, conpredominancia de arena presentan mayor cantidad de macroporos en comparación a suelos de textura fina en donde se observó mayor cantidad de microporos.En relación a los aspectos químicos, el pH en suelos originados de rocas sedimentarias presenta menor rango en relación a los suelos originados de basalto. En cuanto a la acidez intercambiable, el nivel fue mayor en suelos originados de roca sedimentaria que los suelos de textura fina. Las sumas de bases, el contenido de materia orgánica y el nivel de fósforo sin embargo presentaron rangos menores para suelos de textura gruesa en relación a los suelos de textura fina
Prospects for the direct detection of neutralino dark matter in orbifold scenarios
We analyse the phenomenology of orbifold scenarios from the heterotic
superstring, and the resulting theoretical predictions for the direct detection
of neutralino dark matter. In particular, we study the parameter space of these
constructions, computing the low-energy spectrum and taking into account the
most recent experimental and astrophysical constraints, as well as imposing the
absence of dangerous charge and colour breaking minima. In the remaining
allowed regions the spin-independent part of the neutralino-proton cross
section is calculated and compared with the sensitivity of dark matter
detectors. In addition to the usual non universalities of the soft terms in
orbifold scenarios due to the modular weight dependence, we also consider
D-term contributions to scalar masses. These are generated by the presence of
an anomalous U(1), providing more flexibility in the resulting soft terms, and
are crucial in order to avoid charge and colour breaking minima. Thanks to the
D-term contribution, large neutralino detection cross sections can be found,
within the reach of projected dark matter detectors.Comment: 51 pages, 25 figure
PAMELA/ATIC Anomaly from Exotic Mediated Dark Matter Decay
We discuss dark matter decay mediated by exotically charged particles
("exotics") in a supersymmetric model with two dark matter (DM) components: One
is the (bino-like) lightest supersymmetric particle (LSP) \chi, and the other
is a newly introduced meta-stable neutral singlet . decays to \chi
e^+e^- via a dimension 6 operator induced by a penguin-type one loop diagram
with the life time of 10^{26} sec., explaining energetic cosmic e^\pm excess
observed recently by PAMELA and ATIC/PPB-BETS. The superheavy masses of exotics
(\sim 10^{15-16} GeV) are responsible for the longevity of . The
superpartner of develops the vacuum expectation value (VEV) of order TeV so
that the DM achieves the desired mass of 2 TeV. By the VEV, the U(1)_R
symmetry is broken to the discrete Z_2 symmetry, which is identified with the
matter parity in the minimal supersymmetric standard model (MSSM). Since we
have the two DM components, even extremely small amount of [O(10^{-10}) <
(n_N/n_\chi)] could account for the observed positron flux with relatively
light exotics' masses [10^{12} GeV < M_{exo.} < 10^{16} GeV].Comment: 1+7 pages, version to appear in JHE
Surface and porous characterisation of activated carbons made from a novelbiomass precursor, the esparto grass
In the work now reported the production of activated carbons from a novel precursor, esparto grass, by activation with carbon dioxide is presented. The results show that the materials produced have interesting properties, namely BET apparent surface area and pore volume up to 1122 m(2) g(-1) and 0.46 cm(3) g(-1), respectively. The activated carbons have basic characteristics with point of zero charge between 9.25 and 10.27 and show a very fascinating structure, as shown by the SEM images. (C) 2012 Elsevier B.V. All rights reserved.The authors are grateful to the Fundacao para a Ciencia e Tecnologia (Portugal) and the European Regional Development Fund (FEDER) through the Operational Programme for Competitiveness Factors (COMPETE) and QREN for financial support through Project PTDC/CTM/66552/2006 (FCOMP-01-0124-FEDER-007142) and under the Strategic Project PEst-OE/QUI/UI0619/2011 (CQE/UE).Valente Nabais, J.; Laginhas, C.; Ribeiro Carrott, MML.; Carrott, PJM.; Crespo Amorós, JE.; Nadal Gisbert, AV. (2013). Surface and porous characterisation of activated carbons made from a novelbiomass precursor, the esparto grass. Applied Surface Science. 265:919-924. doi:10.1016/j.apsusc.2012.11.164S91992426
PAMELA/ATIC anomaly from the meta-stable extra dark matter component and the leptophilic Yukawa interaction
We present a supersymmetric model with two dark matter (DM) components
explaining the galactic positron excess observed by PAMELA/HEAT and
ATIC/PPB-BETS: One is the conventional (bino-like) lightest supersymmetric
particle (LSP) \chi, and the other is a TeV scale meta-stable neutral singlet
N_D, which is a Dirac fermion (N,N^c). In this model, N_D decays dominantly
into \chi e^+e^- through an R parity preserving dimension 6 operator with the
life time \tau_N\sim 10^{26} sec. We introduce a pair of vector-like superheavy
SU(2) lepton doublets (L,L^c) and lepton singlets (E,E^c). The dimension 6
operator leading to the N_D decay is generated from the leptophilic Yukawa
interactions by W\supset Ne^cE+Lh_dE^c+m_{3/2}l_1L^c with the dimensionless
couplings of order unity, and the gauge interaction by {\cal L}\supset \sqrt{2}
g'\tilde{e}^{c*}e^c\chi + h.c. The superheavy masses of the vector-like leptons
(M_L, M_E\sim 10^{16} GeV) are responsible for the longevity of N_D. The low
energy field spectrum in this model is just the MSSM fields and N_D. Even for
the case that the portion of N_D is much smaller than that of \chi in the total
DM density [{\cal O}(10^{-10}) \lesssim n_{N_D}/n_\chi], the observed positron
excess can be explained by adopting relatively lighter masses of the
vector-like leptons (10^{13} GeV \lesssim M_{L,E} \lesssim 10^{16} GeV). The
smallness of the electron mass is also explained. This model is easily embedded
in the flipped SU(5) grand unification, which is a leptophilic unified theory.Comment: 12 pages, published versio
PP-239 Ancylostoma spp. in soil of public recreative areas of Culiacan and Navolato Sinaloa, Mexico
Epidemiological trends of HIV/HCV coinfection in Spain, 2015-2019
Altres ajuts: Spanish AIDS Research Network; European Funding for Regional Development (FEDER).Objectives: We assessed the prevalence of anti-hepatitis C virus (HCV) antibodies and active HCV infection (HCV-RNA-positive) in people living with HIV (PLWH) in Spain in 2019 and compared the results with those of four similar studies performed during 2015-2018. Methods: The study was performed in 41 centres. Sample size was estimated for an accuracy of 1%. Patients were selected by random sampling with proportional allocation. Results: The reference population comprised 41 973 PLWH, and the sample size was 1325. HCV serostatus was known in 1316 PLWH (99.3%), of whom 376 (28.6%) were HCV antibody (Ab)-positive (78.7% were prior injection drug users); 29 were HCV-RNA-positive (2.2%). Of the 29 HCV-RNA-positive PLWH, infection was chronic in 24, it was acute/recent in one, and it was of unknown duration in four. Cirrhosis was present in 71 (5.4%) PLWH overall, three (10.3%) HCV-RNA-positive patients and 68 (23.4%) of those who cleared HCV after anti-HCV therapy (p = 0.04). The prevalence of anti-HCV antibodies decreased steadily from 37.7% in 2015 to 28.6% in 2019 (p < 0.001); the prevalence of active HCV infection decreased from 22.1% in 2015 to 2.2% in 2019 (p < 0.001). Uptake of anti-HCV treatment increased from 53.9% in 2015 to 95.0% in 2019 (p < 0.001). Conclusions: In Spain, the prevalence of active HCV infection among PLWH at the end of 2019 was 2.2%, i.e. 90.0% lower than in 2015. Increased exposure to DAAs was probably the main reason for this sharp reduction. Despite the high coverage of treatment with direct-acting antiviral agents, HCV-related cirrhosis remains significant in this population
International Lower Limb Collaborative (INTELLECT) study : a multicentre, international retrospective audit of lower extremity open fractures
Efficacy of bacterin-, outer membrane protein- and fimbriae extract-based vaccines for the control of Salmonella Enteritidis experimental infection in chickens
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