2,444 research outputs found
Comparison between an integral and algebraic formulation for the eddy diffusivity using the Copenhagen experimental dataset
In this work an algebraic formulation to evaluate the eddy diffusivities in the Convective Boundary Layer (CBL) is derived. The expression depends on the turbulence properties (z height dependence) and the distance from the source. It is based on the turbulent kinetic energy spectra and Taylor’s statistical diffusion theory. It has been tested and compared through an experimental dataset, with
another complex integral formulation taken from the literature. The Agreement between the complex integral formulation and simple algebraic expression points out that this new parameterization is valid and can be used as a surrogate for eddy diffusivities in the inhomogeneous convective turbulence present in the CBL. The validation shows that the proposed algebraic vertical eddy diffusivity is suitable for application in advanced air quality regulatory models
The behavior of kinetic parameters in production of pectinase and xylanase by solid-state fermentation
AbstractSolid-state fermentation (SSF) is defined as the growth of microbes without a free-flowing aqueous phase. The feasibility of using a citrus peel for producing pectinase and xylanase via the SSF process by Aspergillus niger F3 was evaluated in a 2kg bioreactor. Different aeration conditions were tested to optimize the pectinase and xylanase production. The best air flow intensity was 1VkgM (volumetric air flow per kilogram of medium), which allowed a sufficient amount of O2 for the microorganism growth producing 265U/g and 65U/g pectinases and xylanases, respectively. A mathematical model was applied to determine the different kinetic parameters related to SSF. The specific growth rate and biomass oxygen yield decreased during fermentation, whereas an increase in the maintenance coefficient for the different employed carbon sources was concurrently observed
Euclid: Superluminous supernovae in the Deep Survey
Context. In the last decade, astronomers have found a new type of supernova called superluminous supernovae (SLSNe) due to their high peak luminosity and long light-curves. These hydrogen-free explosions (SLSNe-I) can be seen to z ~ 4 and therefore, offer the possibility of probing the distant Universe.
Aims. We aim to investigate the possibility of detecting SLSNe-I using ESA’s Euclid satellite, scheduled for launch in 2020. In particular, we study the Euclid Deep Survey (EDS) which will provide a unique combination of area, depth and cadence over the mission.
Methods. We estimated the redshift distribution of Euclid SLSNe-I using the latest information on their rates and spectral energy distribution, as well as known Euclid instrument and survey parameters, including the cadence and depth of the EDS. To estimate the uncertainties, we calculated their distribution with two different set-ups, namely optimistic and pessimistic, adopting different star formation densities and rates. We also applied a standardization method to the peak magnitudes to create a simulated Hubble diagram to explore possible cosmological constraints.
Results. We show that Euclid should detect approximately 140 high-quality SLSNe-I to z ~ 3.5 over the first five years of the mission (with an additional 70 if we lower our photometric classification criteria). This sample could revolutionize the study of SLSNe-I at z > 1 and open up their use as probes of star-formation rates, galaxy populations, the interstellar and intergalactic medium. In addition, a sample of such SLSNe-I could improve constraints on a time-dependent dark energy equation-of-state, namely w(a), when combined with local SLSNe-I and the expected SN Ia sample from the Dark Energy Survey.
Conclusions. We show that Euclid will observe hundreds of SLSNe-I for free. These luminous transients will be in the Euclid data-stream and we should prepare now to identify them as they offer a new probe of the high-redshift Universe for both astrophysics and cosmology.Acknowledgements. We thank the internal EC referees (P. Nugent and J.
Brichmann) as well as the many comments from our EC colleagues and friends.
C.I. thanks Chris Frohmaier and Szymon Prajs for useful discussions about
supernova rates. C.I. and R.C.N. thank Mark Cropper for helpful information
about the V IS instrument. C.I. thanks the organisers and participants of the
Munich Institute for Astro- and Particle Physics (MIAPP) workshop “Superluminous supernovae in the next decade” for stimulating discussions and the
provided online material. The Euclid Consortium acknowledges the European
Space Agency and the support of a number of agencies and institutes that
have supported the development of Euclid. A detailed complete list is available on the Euclid web site (http://www.euclid-ec.org). In particular the
Agenzia Spaziale Italiana, the Centre National dEtudes Spatiales, the Deutsches
Zentrum für Luft- and Raumfahrt, the Danish Space Research Institute, the Fundação para a Ciênca e a Tecnologia, the Ministerio de Economia y Competitividad, the National Aeronautics and Space Administration, The Netherlandse
Onderzoekschool Voor Astronomie, the Norvegian Space Center, the Romanian
Space Agency, the State Secretariat for Education, Research and Innovation
(SERI) at the Swiss Space Office (SSO), the United Kingdom Space Agency,
and the University of Helsinki. R.C.N. acknowledges partial support from the
UK Space Agency. D.S. acknowledges the Faculty of Technology of the University of Portsmouth for support during his PhD studies. C.I. and S.J.S. acknowledge funding from the European Research Council under the European
Union’s Seventh Framework Programme (FP7/2007-2013)/ERC Grant agreement No. [291222]. C.I. and M.S. acknowledge support from EU/FP7-ERC
grant No. [615929]. E.C. acknowledge financial contribution from the agreement ASI/INAF/I/023/12/0. The work by KJ and others at MPIA on NISP was
supported by the Deutsches Zentrum für Luft- und Raumfahrt e.V. (DLR) under
grant 50QE1202. M.B. and S.C. acknowledge financial contribution from the
agreement ASI/INAF I/023/12/1. R.T. acknowledges funding from the Spanish
Ministerio de Economía y Competitividad under the grant ESP2015-69020-C2-
2-R. I.T. acknowledges support from Fundação para a Ciência e a Tecnologia
(FCT) through the research grant UID/FIS/04434/2013 and IF/01518/2014. J.R.
was supported by JPL, which is run under a contract for NASA by Caltech and
by NASA ROSES grant 12-EUCLID12-0004
Hydrothermal synthesis to water-stable luminescent carbon dots from acerola fruit for photoluminescent composites preparation and its application as sensors
Carbon dots (C-dots) possess the attractive properties of high stability, low toxicity, good water solubility, simple synthetic routes as well as size and excitation-dependent photoluminescence (PL).The aim of this work was to synthesize photoluminescent C-dots by hydrothermal method using acerola fruit (Malpighiaemarginata) as a row material, since this fruit contains large number of organic molecules. Studies about the optimal synthesis conditions were performed, where these organic molecules were converted into C-dots by hydrothermal carbonization at 180 ºC for 18 h. The C-dots exhibited a green emission light at 459 nm when excited under UV-light (λ ex= 370 nm). These nanomaterials were also successfully used to prepare C-dots/poly (vinyl alcohol) luminescent composites (C-dots/PVA). Both C-dots and C-dots/PVA composite films were investigated by using colorimetric visual sensor for Fe3+ metal ions detection. The results show that the prepared C-dots and C-dots/poly presented strong green emission light. The emission spectra of above materials were quenched in the presence of Fe3+ ions. Thus, highly specific “turn off” fluorescence sensing of Fe3+ was achieved using fluorescent C-dots. Regarding, this work describe that the polymeric films as sensors of metallic ions in aqueous solution appears as a new perspectives to design new composite materials22
Geochemistry of groundwater from Graciosa Island (Azores): A contribution to the hydrothermal system conceptual model
Graciosa island is located in the Azores Archipelago,
along the so-called Terceira Rift, a major tectonic structure
that makes the NE boundary of the Azores Plateau. In general
terms, it includes a basaltic plataform on the NW and a silicic
poligenetic volcano with caldera on the SE, the Graciosa
Caldera Volcano. This volcano has produced significant
tephra falls, pyroclastic flows, lahars, and lava flows, both of
basaltic s.l. and trachitic s.l. composition.
The hydrothermal system shows fumarolic emissions
inside the volcano caldera and thermal springs located along
the shoreline. This system is exploitated in a thermal building
through shallow and deep (110 m) boreholes, near the coast.
In Graciosa two types of Na-Cl groundwater systems can
be identified: 1) a cold one emerging at springs and exploited
by wells for public water supply, and 2) a hydrothermal
system with temperatures around 40-44 °C. The cold
groundwaters have pH higher than 7 and different degree of
mineralization, according to the proximity to the sea. The
thermal waters show mixing with seawater, pH varying
between 6.20 and 6.94, 166 mg/L of SiO2, and significant
concentration of metals, such as Mn, Fe, Co, Ni, Cu and Zn.
The thermal water mineralization varies strongly, showing EC
from 8.87 mS/cm (shallow water) to 47.4 mS/cm (deeper
water). The higher mineralized water is rich in CO2(g), with
2130 mg/L of total dissolved CO2. Geothermometers
application reveals aquifer temperature around 167 °C and
immature/mixed waters, not reaching complete equilibrium
with reservoir rock.
The geochemistry of the thermal waters indicates the
occurrence of seawater/host rock interaction processes at high
temperature and slightly acid conditions, favored by CO2(g)
input, and a different degrees of mixing with cold and shallow
groundwaters
Tau Flavour Violation in Sparticle Decays at the LHC
We consider sparticle decays that violate tau lepton number, motivated by
neutrino oscillation data. We work in the context of the constrained minimal
supersymmetric extension of the Standard Model (CMSSM), in which the different
sleptons have identical masses at the GUT scale, and neutrino Dirac Yukawa
couplings mix them. We find that the branching ratio for decay of the heavier
neutralino chi_2 to chi + tau mu is enhanced when the LSP mass m_chi =
m_stau_1, including the region of CMSSM parameter space where coannihilation
keeps the relic chi density within the range preferred by cosmology. Thus chi_2
to chi + tau mu decay may provide a physics opportunity for observing the
violation of tau lepton number at the LHC that is complementary to tau to mu +
gamma decay. Likewise, chi_2 to chi + e mu decay is also enhanced in the
coannihilation region, providing a complement to mu to e + gamma decay.Comment: 11 pages, 3 figure
Experimental and numerical simulations of oblique extreme wave conditions in front of a breakwater's trunk and round head
ABSTARCT: Climate change studies already reported sea level rise as an accepted scenario, which induces changes in nearshore wave conditions. A large range of new experiences including water level, run-up, overtopping, hydrodynamic data for different wave steepnesses and directions was performed in the Leibniz Universität Hannover (LUH) wave basin for a rubble mound breakwater with a slope of 1(V):2(H). This work presents, focusing on oblique extreme wave conditions, numerical simulations of the hydrodynamics in that experiment using OpenFOAM®. Results of the wave generation boundary conditions and their propagation, namely elevation of the water level free-surface and velocity data at specific locations are compared and discussed with data from experimental measurements acquired by acoustic wave gauges and acoustic doppler velocimeter (ADV) / Vectrino equipment. Although an exact match between numerical and laboratory values was not reached, an appropriate incident wave angle and a reasonable amplitude of velocities and water depths was achieved and the same happened to the statistics of those values
On Weierstra{\ss} semigroups at one and two points and their corresponding Poincar\'e series
The aim of this paper is to introduce and investigate the Poincar\'e series
associated with the Weierstra{\ss} semigroup of one and two rational points at
a (not necessarily irreducible) non-singular projective algebraic curve defined
over a finite field, as well as to describe their functional equations in the
case of an affine complete intersection.Comment: Beginning of Section 3 and Subsection 3.1 were modifie
Positive mental health in university students and its relations with psychological vulnerability, mental health literacy, and sociodemographic characteristics: a descriptive correlational study
This study aimed to evaluate positive mental health (PMH) and its relation with sociodemographic characteristics, mental health literacy, and the psychological vulnerability scale (PVS) in Portuguese university students aged 17 to 62. A descriptive correlational study was carried out. An online survey was conducted to evaluate demographic variables, and several questionnaires were applied to evaluate positive mental health, psychological vulnerability, and mental health literacy. The data was collected from 1 November 2019 to 1 September 2020. Overall, 3405 students participated in the study. The results show that 67.8% of students revealed a high level of PMH, 31.6% presented a medium level of PMH, and 0.6% had a low level of PMH. Male students reported higher personal satisfaction (t (3170) = −2.39, p = 0.017) and autonomy (t (3170) = −3.33, p = 0.001) in PMH compared to female students. Students without a scholarship scored higher (t (3127) = −2.04, p = 0.42) in PMH than students who held a scholarship. Students who were not displaced from their home reported higher (t (3170) = −1.99, p = 0.047) self-control in PMH than those displaced from their home. University students with higher PMH results had lower PVS results and higher literacy results. The findings of this study will contribute to identifying students’ PMH intervention needs.info:eu-repo/semantics/publishedVersio
Wolbachia pipientis: first detection in populations of Glycaspis brimblecombei (Hemiptera: Aphalaridae) and Psyllaephagus bliteus (Hymenoptera: Encyrtidae) in Brazil
The sucking insect, Glycaspis brimblecombei Moore (Hemiptera: Aphalaridae), is originally from Australia and reduces the productivity of Eucalyptus crops. The parasitoid Psyllaephagus bliteus Riek (Hymenoptera: Encyrtidae) is the main agent used in the integrated management of G. brimblecombei. Endosymbionts, in insects, are important in the adaptation and protection of their hosts to the environment. The intracellular symbionts Wolbachia, induces reproductive changes such as cytoplasmic incompatibility, feminization, male death and parthenogenesis. The objective of this study was to report the first record of Wolbachia pipientis in populations of G. brimblecombei and of its parasitoid P. bliteus in the field in Brazil. Branches with adults of G. brimblecombei and P. bliteus were collected from eucalyptus trees in commercial farms in six Brazilian states and, after emergence, the insects obtained were frozen at -20 °C. Polymerase chain reaction (PCR) was performed to detect the Wolbachia endosymbiont.
Wolbachia pipientis was identified in individuals of G. brimblecombei and its parasitoid P. bliteus from populations of the counties of Agudos and Mogi-Guaçu (São Paulo State), Itamarandiba (Minas Gerais State) and São Jerônimo da Serra (Paraná State) in Brazi
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