Search results for "Brown"
showing 10 items of 478 documents
Effect of a novel physical pretreatment process on the drying kinetics of seedless grapes
2000
In this paper an alternative physical method for enhancing the drying rate of seedless grapes is proposed. It consists of the superficial abrasion of the grape peel using an inert abrasive material. The effectiveness of this novel process was compared to that of the traditional ethyl oleate dipping process by analysing not only their respective drying times, but also the peel surfaces by scanning electron microscopy. Moreover, the drying kinetics of the above two treatments was reconstructed by using a mathematical model in which the grape pretreatment used was assumed to affect the water diffusivity in the grape peel, but not in the grape pulp. Even though the abrasion method was found to …
The brown dwarf population in the Chamaeleon I cloud
2003
We present the results of a multiband survey for brown dwarfs in the Chamaeleon I dark cloud with the Wide Field Imager (WFI) camera at the ESO/MPG 2.2-m telescope on La Silla (Chile). The survey has revealed a substantial population of brown dwarfs in this southern star forming region. Candidates were selected from R, I and H-alpha imaging observations. We also observed in two medium-band filters, M855 and M915, for the purpose of spectral type determination. The former filter covers a wavelength range containing spectral features characteristic of M-dwarfs, while the latter lies in a relatively featureless wavelength region for these late-type objects. A correlation was found between spec…
Hemocyte types and some plasmatic properties of two edible crabs Cancer borealis and Cancer pagurus
2015
Cancer pagurus and Cancer borealis and are edible crabs produced by economically relevant aquaculture. In this study the hemocytes and some plasmatic parameters of Cancer borealis and Cancer pagurus were examined. The cell features of the hemocytes were observed using light and scanning electron microscopy (SEM). Granulocytes, semigranulocytes and hyalinocytes were mainly identified on the basis of size, presence/absence and quantity of the cytoplasmic granules and the nucleus-to-citoplasma (N/C) ratio. SEM observations were useful for disclosing the surface features of these cells, and the same characteristics were found in both crab species. A smooth surface distinguishes elongated hyalin…
THE ROLE OF NON-GAUSSIAN SOURCES IN THE TRANSIENT DYNAMICS OF LONG JOSEPHSON JUNCTIONS
2013
We analyze the effects of different non-Gaussian noise sources on the transient dynamics of an overdamped long Josephson junction. We find nonmonotonic behavior of the mean escape time as a function of the noise intensity and frequency of the external driving signal for all the noise sources investigated.
Phase dynamics in graphene-based Josephson junctions in the presence of thermal and correlated fluctuations
2014
In this work we study by numerical methods the phase dynamics in ballistic graphene-based short Josephson junctions. The supercurrent through a graphene junction shows a non-sinusoidal phase-dependence, unlike a conventional junction ruled by the well-known d.c. Josephson relation. A superconductor-graphene-superconductor system exhibits superconductive quantum metastable states similar to those present in normal current-biased JJs. We explore the effects of thermal and correlated fluctuations on the escape time from these metastable states, when the system is stimulated by an oscillating bias current. As a first step, the analysis is carried out in the presence of an external Gaussian whit…
RELAXATION PHENOMENA IN CLASSICAL AND QUANTUM SYSTEMS
2012
Relaxation phenomena in three different classical and quantum systems are investigated. First, the role of multiplicative and additive noise in a classical metastable system is analyzed. The mean lifetime of the metastable state shows a nonmonotonicbehavior with a maximum as a function of both the additive and multiplicative noise intensities. In the second system, the simultaneous action of thermal and non-Gaussian noise on the dynamics of an overdamped point Josephson junction is studied. The effect of a Lévy noise generated by a Cauchy–Lorentz distribution on the mean lifetime of the superconductive metastable state, in the presence of a periodic driving, is investigated. We find resonan…
Co-occurrence of resonant activation and noise-enhanced stability in a model of cancer growth in the presence of immune response.
2006
We investigate a stochastic version of a simple enzymatic reaction which follows the generic Michaelis-Menten kinetics. At sufficiently high concentrations of reacting species, the molecular fluctuations can be approximated as a realization of a Brownian dynamics for which the model reaction kinetics takes on the form of a stochastic differential equation. After eliminating a fast kinetics, the model can be rephrased into a form of a one-dimensional overdamped Langevin equation. We discuss physical aspects of environmental noises acting in such a reduced system, pointing out the possibility of coexistence of dynamical regimes where noise-enhanced stability and resonant activation phenomena …
Allochthony, fatty acid and mercury trends in muscle of Eurasian perch (Perca fluviatilis) along boreal environmental gradients
2022
Environmental change, including joint effects of increasing dissolved organic carbon (DOC) and total phosphorus (TP) in boreal northern lakes could potentially affects food web energy sources and the biochemical composition of organisms. These environmental stressors are enhanced by anthropogenic land-use and can decrease the quality of polyunsaturated fatty acids (PUFAs) in seston and zooplankton, and therefore, possibly cascading up to fish. In contrast, the content of mercury in fish increases with lake browning potentially amplified by intensive forestry practises. However, there is little evidence on how these environmental stressors simultaneously impact beneficial omega-3 fatty acid …
Gaussian models for the distribution of Brownian particles in tilted periodic potentials
2011
We present two Gaussian approximations for the time-dependent probability density function (PDF) of an overdamped Brownian particle moving in a tilted periodic potential. We assume high potential barriers in comparison with the noise intensity. The accuracy of the proposed approximated expressions for the time-dependent PDF is checked with numerical simulations of the Langevin dynamics. We found a quite good agreement between theoretical and numerical results at all times.
Removal of Cypermethrin from Water by Using Fucus Spiralis Marine Alga
2019
Alpha-cypermethrin is a synthetic pyrethroid that was extensively used for insect control, since the early 1980s. However, it is known that its presence in the environment has toxic effects on humans and aquatic life forms. For this reason, it is commendable for it to be removed completely from the contaminated environment. In this study, we evaluated the adsorption capacity of a marine alga for the removal of cypermethrin from water. The adsorption experiments were performed based on the batch equilibrium technique. The samples containing the pesticide were analyzed using gas chromatography with an electron capture detector, after liquid-liquid extraction in hexane. The results obtained fr…