10,550 research outputs found
The Chemical Composition of Cernis 52 (BD+31 640)
We present an abundance analysis of the star Cernis 52 in whose spectrum we
recently reported the napthalene cation in absorption at 6707.4 {\AA}. This
star is on a line of sight to the Perseus molecular complex. The analysis of
high-resolution spectra using a chi^2-minimization procedure and a grid of
synthetic spectra provides the stellar parameters and the abundances of O, Mg,
Si, S, Ca, and Fe. The stellar parameters of this star are found to be T_{eff}
= 8350 +- 200 K, logg= 4.2 +- 0.4 dex. We derived a metallicity of [Fe/H] =
-0.01 +- 0.15. These stellar parameters are consistent with a star of
\Msun in a pre-main-sequence evolutionary stage. The stellar spectrum is
significantly veiled in the spectral range 5150-6730 {\AA} up to almost 55 per
cent of the total flux at 5150 {\AA} and decreasing towards longer wavelengths.
Using Johnson-Cousins and 2MASS photometric data, we determine a distance to
Cernis 52 of 231 pc considering the error bars of the stellar
parameters. This determination places the star at a similar distance to the
young cluster IC 348. This together with its radial velocity, v_r=13.7+-1 km/s,
its proper motion and probable young age support Cernis 52 as a likely member
of IC 348. We determine a rotational velocity of v\sin i=65 +- 5 km/s for this
star. We confirm that the stellar resonance line of \ion{Li}{1} at 6707.8 {\AA}
is unable to fit the broad feature at 6707.4 {\AA}. This feature should have a
interstellar origin and could possibly form in the dark cloud L1470 surrounding
all the cluster IC 348 at about the same distance.Comment: Accepted for publication in The Astrophysical Journa
Performance analysis of Ti-Nb-Zr-Ta to development medium entropy alloys by powder metallurgy
The field of biomedical high entropy alloys has become a vital area because they can make human life easier. The most alloys used in biomedical application are Ti6Al4V due to the titanium element. Pure titanium (CP-Ti) has excellent corrosion resistance but the titanium and its alloys have high price [1, 2]. High Entropy Alloys (HEAs) are defined as alloys that consist of five main elements or more mixed in an equiatomic, near-equiatomic and equimasic fraction [3]. The behavior is being investigated for high entropy alloying elements and the design methods. Powder metallurgical techniques can be used to obtain HEA based on compatible alloy for biomedical applications with uncomplicated and inexpensive way to process. The demanded alloys for biomedical applications are excellent in plasticity, low in Young modulus, and high in strength; the alloy components are low-toxicity and are completely free from them. Many HEAs have superior mechanical properties, microstructure and good biocompatibility [4-7], in contrast to Ti6Al4V when used for bone implants; it has been shown that there is significant bone wear. Besides, aluminum and vanadium can have adverse effects on the human body [8]. In this work, a medium entropy alloys (MEA) base on Ti-Nb-Zr-Ta system (Ti25Nb25Zr25Ta25) has been studied using conventional powder metallurgy techniques. Their microstructure, mechanical properties and chemical properties have also been studied. The results obtained demonstrate the influence and performance of equiatomic and equimasic of these alloys and their ability to work successfully for possible use as biomedical implants
Non-equilibrium electronic transport in a one-dimensional Mott insulator
We calculate the non-equilibrium electronic transport properties of a
one-dimensional interacting chain at half filling, coupled to non-interacting
leads. The interacting chain is initially in a Mott insulator state that is
driven out of equilibrium by applying a strong bias voltage between the leads.
For bias voltages above a certain threshold we observe the breakdown of the
Mott insulator state and the establishment of a steady-state electronic current
through the system. Based on extensive time-dependent density matrix
renormalization group simulations, we show that this steady-state current
always has the same functional dependence on voltage, independent of the
microscopic details of the model and relate the value of the threshold to the
Lieb-Wu gap. We frame our results in terms of the Landau-Zener dielectric
breakdown picture. Finally, we also discuss the real-time evolution of the
current, and characterize the current-carrying state resulting from the
breakdown of the Mott insulator by computing the double occupancy, the spin
structure factor, and the entanglement entropy.Comment: 12 pages RevTex4, 12 eps figures, as published, minor revision
Importance Sampling for Objetive Funtion Estimations in Neural Detector Traing Driven by Genetic Algorithms
To train Neural Networks (NNs) in a supervised way, estimations of an objective function must be carried out. The value of this function decreases as the training progresses and so, the number of test observations necessary for an accurate estimation has to be increased. Consequently, the training computational cost is unaffordable for very low objective function value estimations, and the use of Importance Sampling (IS) techniques becomes convenient. The study of three different objective functions is considered, which implies the proposal of estimators of the objective function using IS techniques: the Mean-Square error, the Cross Entropy error and the Misclassification error criteria. The values of these functions are estimated by IS techniques, and the results are used to train NNs by the application of Genetic Algorithms. Results for a binary detection in Gaussian noise are provided. These results show the evolution of the parameters during the training and the performances of the proposed detectors in terms of error probability and Receiver Operating Characteristics curves. At the end of the study, the obtained results justify the convenience of using IS in the training
Equilibrium Behaviour of Creative Accounting Practices for Financing Externally Evidence from Turkey
This paper examines the impact of using creative accounting practices on external
financing processes and the priorities available to Turkish manufacturing firms in
achieving equilibrium reporting strategies for external financing at the lowest possible
cost. Following a literature review, creative accounting practices are measured to
demonstrate steady earnings streams as an income smoothing strategy in Big Bath theory's scope using unexpected accruals to justify external financing. Since the management can maintain its presence at the lowest costs resulting from economic fluctuations in the Turkish market, the firm priorities for external financing are determined rationally to fund capital expenditures or finance operations sustainably without depleting financial resources by adopting equilibrium reporting strategies represented by the creative accounting practices. The paper data are collected from 143 Turkish manufacturing firms listed in the Istanbul Stock Exchange using the Orbis database in 2015-2019. Multiple regression is used to test hypotheses. The study concluded that unexpected accruals are significantly related to external financing to achieve sustainable growth, but it is not strong enough. Some determinants have a positive moderating effect on the negative relationship between earnings management and external financing needs. This paper provides new insights into the Turkish market regarding managers priorities for creative accounting practices. It gives broader horizons to research some of the determinants that may affect the relationship between creative accounting practices and external financin
Wavelet entropy of stochastic processes
We compare two different definitions for the wavelet entropy associated to
stochastic processes. The first one, the Normalized Total Wavelet Entropy
(NTWS) family [Phys. Rev. E 57 (1998) 932; J. Neuroscience Method 105 (2001)
65; Physica A (2005) in press] and a second introduced by Tavares and Lucena
[Physica A 357 (2005)~71]. In order to understand their advantages and
disadvantages, exact results obtained for fractional Gaussian noise (-1<alpha<
1) and the fractional Brownian motion (1 < alpha < 3) are assessed. We find out
that NTWS family performs better as a characterization method for these
stochastic processes.Comment: 12 pages, 4 figures, submitted to Physica
The effect of seasoning with herbs on the nutritional, safety and sensory properties of reduced-sodium fermented Cobrançosa cv. table olives
This study aimed at evaluating the effectiveness of seasoning Cobrancosa table olives in a brine with aromatic ingredients, in order to mask the bitter taste given by KCl when added to reduced-sodium fermentation brines. Olives were fermented in two different salt combinations: Brine A, containing 8% NaCl and, Brine B, a reduced-sodium brine, containing 4% NaCl + 4% KCl. After the fermentation the olives were immersed in seasoning brines with NaCl (2%) and the aromatic herbs (thyme, oregano and calamintha), garlic and lemon. At the end of the fermentation and two weeks after seasoning, the physicochemical, nutritional, organoleptic, and microbiological parameters, were determined. The olives fermented in the reduced-sodium brines had half the sodium concentration, higher potassium and calcium content, a lower caloric level, but were considered, by a sensorial panel, more bitter than olives fermented in NaCl brine. Seasoned table olives, previously fermented in Brine A and Brine B, had no significant differences in the amounts of protein (1.23% or 1.11%), carbohydrates (1.0% or 0.66%), fat (20.0% or 20.5%) and dietary fiber (3.4% or 3.6%). Regarding mineral contents, the sodium-reduced fermented olives, presented one third of sodium, seven times more potassium and three times more calcium than the traditional olives fermented in 8% NaCl. Additionally, according to the panelists' evaluation, seasoning the olives fermented in 4% NaCl + 4% KCl, resulted in a decrease in bitterness and an improvement in the overall evaluation and flavor. Escherichia coli and Salmonella were not found in the olives produced.info:eu-repo/semantics/publishedVersio
Ingeniería de proteínas fluorescentes y aplicaciones de localización celular en microorganismos termófilos
Tesis doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Biología Molecular. Fecha de lectura: 05-07-201
Identificación de CHIP y Ataxina-2 como modificadores de la toxicidad inducida por la Ataxina-1 utilizando un modelo de ataxia espinocerebelosa tipo 1 en "Drosophila melanogaster"
Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Biología. Fecha de lectura: 22-11-200
Detecting emerging products in TOR network based on K-Shell graph decomposition
En este documento, presentamos un marco semiautomático que permite identificar los más populares y también, algunos de los productos ilegales emergentes que se venden en los mercados que se encuentran en la red oscura (Darknet). Utilizando información textual extraída de los dominios de Darknet, construimos un gráfico de correlaciones de productos (PCG), donde los nodos son productos Darknet y los bordes reflejan una oferta simultánea de dos productos. Aplicando el algoritmo k-Shell para descomponer el gráfico PCG, identificamos los productos contenidos en el núcleo e identificamos los más populares y emergentes. Aplicamos nuestro algoritmo de detección de emergencia al conjunto de datos denominado direcciones de texto de uso de Darknet (DUTA), detectando MDMA y éxtasis como las drogas más relevantes y emergentes, respectivamente, validando estos resultados con el Informe de prestigiosas organizaciones internacionales de drogas. Estos resultados hacen de nuestro marco una herramienta complementaria para extraer información en los mercados ilegales donde no se muestran los registros de transacciones
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