1,868 research outputs found
Effect of Mixotrophy on Lipid Content and Fatty Acids Methyl Esters Profile by Chromochloris zofingiensis Grown in Media Containing Sugarcane Molasses
No full textThe effect of sugarcane molasses on lipid content and fatty acids methyl ester (FAME) profile by Chromochloris zofingiensis is investigated in this work. For this purpose, the strain has been cultivated under mixotrophic conditions in a medium amended with specific concentrations of molasses (0.5 g/L, 1 g/L, and 2 g/L) able to sustain microalgae growth. Better biomass concentration, lipid content, and lipid productivity (1.6 g/L, 38% wt, and 286 mg/L/day) than the control (1.32 g/L, 16% wt, and 139 mg/L/day) were obtained with 2 g/L of molasses. The highest value of the total lipid content (42% wt) was reached with 1 g/L of molasses. FAME profile revealed a 97% composition in C16-C18 with no statistically meaningful differences among the three concentrations of molasses tested. The most represented fatty acids were C18:1 oleic (> 38% wt), C18:2 linoleic (> 21% wt), and C16:0 palmitic (> 14% wt). When using 2 g/L of molasses unsaturated fatty acids reached the highest portion (77%) than the control (61%). Specifically, all FAMEs have been quantitatively and qualitatively analyzed in order to improve biodiesel properties. The main characteristics of biodiesel obtainable from the algal lipids appeared in compliance with ASTM standards for unblended biodiesel and fulfilled European regulations (EN 14,214 and EN 590) for the quality of biodiesel. Owing the compliance of the corresponding biodiesel characteristics with international standards, a profitable biodiesel can be obtained under mixotrophic conditions triggered by the use of a food industry waste
Experimental Results on Multi-modal Deepfake Detection
No full textBook cover
International Conference on Image Analysis and Processing
ICIAP 2022: Image Analysis and Processing – ICIAP 2022 pp 164–175Cite as
Experimental Results on Multi-modal Deepfake Detection
Sara Concas, Jie Gao, Carlo Cuccu, Giulia Orrù, Xiaoyi Feng, Gian Luca Marcialis, Giovanni Puglisi & Fabio Roli
Conference paper
First Online: 17 May 2022
1051 Accesses
Part of the Lecture Notes in Computer Science book series (LNCS,volume 13232)
Abstract
The advantages of deepfakes in many applications are counterbalanced by their malicious use, for example, in reply-attacks against a biometric system, identification evasion, and people harassment, when they are widespread in social networks and chatting platforms (cyberbullying) as recently documented in newspapers. Due to its “arms-race” nature, deepfake detection systems are often trained on a certain class of deepfakes and showed their limits on never-seen-before classes. In order to shed some light on this problem, we explore the benefits of a multi-modal deepfake detection system. We adopted simple fusion rules, which showed their effectiveness in many applications, for example, biometric recognition, to exploit the complementary of different individual classifiers, and derive some possible guidelines for the designer
A spectral method for bipartizing a network and detecting a large anti-community
No full textRelations between discrete quantities such as people, genes, or streets can be described by networks, which consist of nodes that are connected by edges. Network analysis aims to identify important nodes in a network and to uncover structural properties of a network. A network is said to be bipartite if its nodes can be subdivided into two nonempty sets such that there are no edges between nodes in the same set. It is a difficult task to determine the closest bipartite network to a given network. This paper describes how a given network can be approximated by a bipartite one by solving a sequence of fairly simple optimization problems. The algorithm also produces a node permutation which makes the possible bipartite nature of the initial adjacency matrix evident, and identifies the two sets of nodes. We finally show how the same procedure can be used to detect the presence of a large anti-community in a network and to identify it
Lipid content and fatty acid methyl ester profile by Chromochloris zofingiensis under chemical and metabolic stress
No full textThis work encompasses the effect of chemical and metabolic stress on lipid content and fatty acid methyl ester (FAME) profile by Chromochloris zofingiensis. To this aim, a control medium amended with specific concentrations of sodium chloride (15 g L-1, 30 g L-1, and 60 g L-1) and of ethanolamine (ETA) and triethylamine (TEA) (0.050 g L-1, 0.100 g L-1, and 0.150 g L-1) has been used for the cultivation of this strain. A better lipid content than the control was obtained under salt stress compared to chemical stress induced by ETA and TEA, while the effect on lipid productivity was negligible. Thirty grams per liter of NaCl allowed to obtain the highest value of the total lipid content (30.33% DW) compared to the control (20% DW). FAME profile revealed a 97.50-98.99% composition in C16-C18 with no statistically meaningful differences among the three concentrations of salt and chemicals tested. The most represented fatty acids were C18:1 oleic (> 45%wt), C16:0 palmitic (> 34%wt), and C18:2 linoleic (> 21%wt) obtained under 60 and 30 mg L-1 of NaCl and 0.150 g L-1 of ETA, respectively. When using 0.150 g L-1 of ETA, unsaturated fatty acids reached the highest portion (67.53%wt) than the control (62.26%wt). A quantitative and qualitative analysis of all FAMEs has been carried out to improve biodiesel properties. Chemical and physical properties of algal lipid-derived biodiesel showed a compliance with ASTM standards for unmixed biodiesel and the main European regulations (EN 14214 and EN 590) for the quality of biodiesel resulted fulfilled. Therefore, a profitable biodiesel can be obtained when cultivating C. zofingiensis under osmotic stress
Lipid content and fatty acid methyl ester profile by Chromochloris zofingiensis under chemical and metabolic stress
No full textThis work encompasses the effect of chemical and metabolic stress on lipid content and fatty acid methyl ester (FAME) profile by Chromochloris zofingiensis. To this aim, a control medium amended with specific concentrations of sodium chloride (15 g L-1, 30 g L-1, and 60 g L-1) and of ethanolamine (ETA) and triethylamine (TEA) (0.050 g L-1, 0.100 g L-1, and 0.150 g L-1) has been used for the cultivation of this strain. A better lipid content than the control was obtained under salt stress compared to chemical stress induced by ETA and TEA, while the effect on lipid productivity was negligible. Thirty grams per liter of NaCl allowed to obtain the highest value of the total lipid content (30.33% DW) compared to the control (20% DW). FAME profile revealed a 97.50-98.99% composition in C16-C18 with no statistically meaningful differences among the three concentrations of salt and chemicals tested. The most represented fatty acids were C18:1 oleic (> 45%wt), C16:0 palmitic (> 34%wt), and C18:2 linoleic (> 21%wt) obtained under 60 and 30 mg L-1 of NaCl and 0.150 g L-1 of ETA, respectively. When using 0.150 g L-1 of ETA, unsaturated fatty acids reached the highest portion (67.53%wt) than the control (62.26%wt). A quantitative and qualitative analysis of all FAMEs has been carried out to improve biodiesel properties. Chemical and physical properties of algal lipid-derived biodiesel showed a compliance with ASTM standards for unmixed biodiesel and the main European regulations (EN 14214 and EN 590) for the quality of biodiesel resulted fulfilled. Therefore, a profitable biodiesel can be obtained when cultivating C. zofingiensis under osmotic stress
Lipid content and fatty acid methyl ester profile by Chromochloris zofingiensis under chemical and metabolic stress
No full textThis work encompasses the effect of chemical and metabolic stress on lipid content and fatty acid methyl ester (FAME) profile by Chromochloris zofingiensis. To this aim, a control medium amended with specific concentrations of sodium chloride (15 g L-1, 30 g L-1, and 60 g L-1) and of ethanolamine (ETA) and triethylamine (TEA) (0.050 g L-1, 0.100 g L-1, and 0.150 g L-1) has been used for the cultivation of this strain. A better lipid content than the control was obtained under salt stress compared to chemical stress induced by ETA and TEA, while the effect on lipid productivity was negligible. Thirty grams per liter of NaCl allowed to obtain the highest value of the total lipid content (30.33% DW) compared to the control (20% DW). FAME profile revealed a 97.50-98.99% composition in C16-C18 with no statistically meaningful differences among the three concentrations of salt and chemicals tested. The most represented fatty acids were C18:1 oleic (> 45%wt), C16:0 palmitic (> 34%wt), and C18:2 linoleic (> 21%wt) obtained under 60 and 30 mg L-1 of NaCl and 0.150 g L-1 of ETA, respectively. When using 0.150 g L-1 of ETA, unsaturated fatty acids reached the highest portion (67.53%wt) than the control (62.26%wt). A quantitative and qualitative analysis of all FAMEs has been carried out to improve biodiesel properties. Chemical and physical properties of algal lipid-derived biodiesel showed a compliance with ASTM standards for unmixed biodiesel and the main European regulations (EN 14214 and EN 590) for the quality of biodiesel resulted fulfilled. Therefore, a profitable biodiesel can be obtained when cultivating C. zofingiensis under osmotic stress
Effect of Mixotrophy on Lipid Content and Fatty Acids Methyl Esters Profile by Chromochloris zofingiensis Grown in Media Containing Sugarcane Molasses
No full textThe effect of sugarcane molasses on lipid content and fatty acids methyl ester (FAME) profile by Chromochloris zofingiensis is investigated in this work. For this purpose, the strain has been cultivated under mixotrophic conditions in a medium amended with specific concentrations of molasses (0.5 g/L, 1 g/L, and 2 g/L) able to sustain microalgae growth. Better biomass concentration, lipid content, and lipid productivity (1.6 g/L, 38% wt, and 286 mg/L/day) than the control (1.32 g/L, 16% wt, and 139 mg/L/day) were obtained with 2 g/L of molasses. The highest value of the total lipid content (42% wt) was reached with 1 g/L of molasses. FAME profile revealed a 97% composition in C16-C18 with no statistically meaningful differences among the three concentrations of molasses tested. The most represented fatty acids were C18:1 oleic (> 38% wt), C18:2 linoleic (> 21% wt), and C16:0 palmitic (> 14% wt). When using 2 g/L of molasses unsaturated fatty acids reached the highest portion (77%) than the control (61%). Specifically, all FAMEs have been quantitatively and qualitatively analyzed in order to improve biodiesel properties. The main characteristics of biodiesel obtainable from the algal lipids appeared in compliance with ASTM standards for unblended biodiesel and fulfilled European regulations (EN 14,214 and EN 590) for the quality of biodiesel. Owing the compliance of the corresponding biodiesel characteristics with international standards, a profitable biodiesel can be obtained under mixotrophic conditions triggered by the use of a food industry waste. Graphical abstract: [Figure not available: see fulltext.
Iterative Methods for the Computation of the Perron Vector of Adjacency Matrices
No full textThe power method is commonly applied to compute the Perron vector of large adjacency matrices. Blondel et al. [SIAM Rev. 46, 2004] investigated its performance when the adjacency matrix has multiple eigenvalues of the same magnitude. It is well known that the Lanczos method typically requires fewer iterations than the power method to determine eigenvectors with the desired accuracy. However, the Lanczos method demands more computer storage, which may make it impractical to apply to very large problems. The present paper adapts the analysis by Blondel et al. to the Lanczos and restarted Lanczos methods. The restarted methods are found to yield fast convergence and to require less computer storage than the Lanczos method. Computed examples illustrate the theory presented. Applications of the Arnoldi method are also discussed
On the robustness of the Hβ Lick index as a cosmic clock in passive early-type galaxies
No full textWe examine the H Lick index in a sample of massive () and passive early-type galaxies extracted from SDSS at
z<0.3, in order to assess the reliability of this index to constrain the epoch
of formation and age evolution of these systems. We further investigate the
possibility of exploiting this index as "cosmic chronometer", i.e. to derive
the Hubble parameter from its differential evolution with redshift, hence
constraining cosmological models independently of other probes. We find that
the H strength increases with redshift as expected in passive evolution
models, and shows at each redshift weaker values in more massive galaxies.
However, a detailed comparison of the observed index with the predictions of
stellar population synthesis models highlights a significant tension, with the
observed index being systematically lower than expected. By analyzing the
stacked spectra, we find a weak [NII] emission line (not
detectable in the single spectra) which anti-correlates with the mass, that can
be interpreted as a hint of the presence of ionized gas. We estimated the
correction of the H index by the residual emission component exploiting
different approaches, but find it very uncertain and model-dependent. We
conclude that, while the qualitative trends of the observed H-z
relations are consistent with the expected passive and downsizing scenario, the
possible presence of ionized gas even in the most massive and passive galaxies
prevents to use this index for a quantitative estimate of the age evolution and
for cosmological applications
On the Use of Agro-industrial Wastewaters to Promote Mixotrophic Metabolism in Chlorella Vulgaris: Effect on Fame Profile and Biodiesel Properties
No full textThe increase of greenhouse gases into the atmosphere, mainly due to industrialization, has affected all the ecosystems. Current worldwide living standards are still heavily dependent on non-renewable fuels. The
inevitable depletion of fossil fuels and the adverse climate changes push the scientific community to seek renewable and sustainable sources of fuel. In this scenario microalgae can be potentially exploited as renewable and environmentally friendly fuel resources. Wastewaters (WW) can be used as culture media minimizing the costs associated to their cultivation. Hence, the goal of this study was to examine the effect of agro-industrial WWs rich in organic nutrients on algal lipid content and fatty acid methyl esters (FAME) profile. For this purpose, the fresh water green algae Chlorella vulgaris was selected. This strain is able to thrive in a wide range of WWs with high biomass productivity and to shift its metabolism from autotrophic to hetero/mixotrophic one. C. vulgaris was cultivated in brewery (BWW), dairy (DWW), oil mill WWs and media supplemented with sugarcane molasses. High biomass yields were obtained when C. vulgaris was cultivated in BWW and DWW (1.76 g L-1 and 1.56 g L-1, respectively) compared to the control and the other WWs. The assessment of FAMEs composition (i.e. level of unsaturation) of algae cultivated under all the investigated conditions demonstrated that the former ones can be viably used as sources for producing biofuels
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