A combined first and second order variational approach for image reconstruction

In this paper we study a variational problem in the space of functions of bounded Hessian. Our model constitutes a straightforward higher-order extension of the well known ROF functional (total variation minimisation) to which we add a non-smooth second order regulariser. It combines convex functions of the total variation and the total variation of the first derivatives. In what follows, we prove existence and uniqueness of minimisers of the combined model and present the numerical solution of the corresponding discretised problem by employing the split Bregman method. The paper is furnished with applications of our model to image denoising, deblurring as well as image inpainting. The obtained numerical results are compared with results obtained from total generalised variation (TGV), infimal convolution and Euler's elastica, three other state of the art higher-order models. The numerical discussion confirms that the proposed higher-order model competes with models of its kind in avoiding the creation of undesirable artifacts and blocky-like structures in the reconstructed images -- a known disadvantage of the ROF model -- while being simple and efficiently numerically solvable.Comment: 34 pages, 89 figure

Evidence for phase formation in potassium intercalated 1,2;8,9-dibenzopentacene

We have prepared potassium intercalated 1,2;8,9-dibenzopentacene films under vacuum conditions. The evolution of the electronic excitation spectra upon potassium addition as measured using electron energy-loss spectroscopy clearly indicate the formation of particular doped phases with compositions K$_x$dibenzopentacene ($x$ = 1,2,3). Moreover, the stability of these phases as a function of temperature has been explored. Finally, the electronic excitation spectra also give insight into the electronic ground state of the potassium doped 1,2;8,9-dibenzopentacene films.Comment: 6 pages, 5 figures. arXiv admin note: text overlap with arXiv:1201.200

Sensitivity of the Mott Transition to Non-cubic Splitting of the Orbital Degeneracy: Application to NH3 K3C60

Within dynamical mean-field theory, we study the metal-insulator transition of a twofold orbitally degenerate Hubbard model as a function of a splitting \Delta of the degeneracy. The phase diagram in the U-\Delta plane exhibits two-band and one-band metals, as well as the Mott insulator. The correlated two-band metal is easily driven to the insulator state by a strikingly weak splitting \Delta << W of the order of the Kondo-peak width zW, where z << 1 is the metal quasiparticle weight. The possible relevance of this result to the insulator-metal transition in the orthorhombic expanded fulleride NH3 K3C60 is discussed.Comment: revtex, 15 pages including 6 ps figures. Submitted to Phys. Rev.

Neuronal Number, Volume, and Apoptosis of the Left Dentate Gyrus of Chronically Stressed Pigs Correlate Negatively With Basal Saliva Cortisol Levels

Although the consequences of stress and hypercortisolemia for the rodent hippocampal dentate gyrus (DG) are well known, little is known about other species. For pigs, tethered housing represents a well-established chronic stressor that shares many similarities with restraint paradigms, as evidenced by profound changes in behavior and autonomic and endocrine dysfunction, including flattened cortisol rhythms and hypercortisolemia all conditions that may threaten hippocampal viability in rat. Here, we studied structural parameters of the porcine DG after 5 months of tethered housing in relation to basal saliva cortisol measured antemortem. We further investigated whether any neuropathology or alterations in apoptosis had occurred in the left hippocampal hemisphere. Stereological analysis revealed high correlations between DG volume and neuron number in individual animals in both hemispheres. Within individual animals, neuron numbers of the left and right lobes were not correlated. Notably, basal cortisol was negatively correlated with volume and neuron number of the left, but not the right DG. Although obvious neuropathology was absent, apoptosis was present in DG and alveus and less so in CA areas. Despite the short window of time during which apoptosis is detectable, their stereologically estimated numbers in the DG, but not in other regions, were negatively correlated with cortisol. In conclusion, our data indicate for the first time a profound lateralization in the relationship between DG structure, apoptosis, and basal cortisol after stress in pigs. Five months of chronic stress failed to induce lasting neuropathology. Although accumulating changes in apoptosis could have contributed to the structural DG alterations, further studies should reveal whether stress has been instrumental, or whether the differences between animals were present from birth onward. The present lateralization after stress is, however, consistent with lateralized hippocampal volume changes in stress-related human disorders and suggests that these effects are not limited to this species alone

Neuronal Number, Volume, and Apoptosis of the Left Dentate Gyrus of Chronically Stressed Pigs Correlate Negatively With Basal Saliva Cortisol Levels

Although the consequences of stress and hypercortisolemia for the rodent hippocampal dentate gyrus (DG) are well known, little is known about other species. For pigs, tethered housing represents a well-established chronic stressor that shares many similarities with restraint paradigms, as evidenced by profound changes in behavior and autonomic and endocrine dysfunction, including flattened cortisol rhythms and hypercortisolemia all conditions that may threaten hippocampal viability in rat. Here, we studied structural parameters of the porcine DG after 5 months of tethered housing in relation to basal saliva cortisol measured antemortem. We further investigated whether any neuropathology or alterations in apoptosis had occurred in the left hippocampal hemisphere. Stereological analysis revealed high correlations between DG volume and neuron number in individual animals in both hemispheres. Within individual animals, neuron numbers of the left and right lobes were not correlated. Notably, basal cortisol was negatively correlated with volume and neuron number of the left, but not the right DG. Although obvious neuropathology was absent, apoptosis was present in DG and alveus and less so in CA areas. Despite the short window of time during which apoptosis is detectable, their stereologically estimated numbers in the DG, but not in other regions, were negatively correlated with cortisol. In conclusion, our data indicate for the first time a profound lateralization in the relationship between DG structure, apoptosis, and basal cortisol after stress in pigs. Five months of chronic stress failed to induce lasting neuropathology. Although accumulating changes in apoptosis could have contributed to the structural DG alterations, further studies should reveal whether stress has been instrumental, or whether the differences between animals were present from birth onward. The present lateralization after stress is, however, consistent with lateralized hippocampal volume changes in stress-related human disorders and suggests that these effects are not limited to this species alone

Prediction of sweet pepper (Capsicum annuum) flavour over different harvests

To better understand and predict the complex multifactorial trait flavor, volatile and non-volatile components were measured in fresh sweet pepper (Capsicum annuum) fruits throughout the growing season in a diverse panel of 24 breeding lines, hybrids, several cultivated genotypes and one gene bank accession. Biochemical profiles were linked to individual flavor attributes, that were objectively quantified by a trained descriptive expert panel. We used a Random Forest regression approach for prediction of the flavor attributes within and between harvests. Predictions of texture related attributes (juiciness, toughness, crunchiness and stickiness of the skin) and sweetness were good (around 60–65 %in the analyses with the three harvests combined). The predictions of the attributes aroma intensity, sourness and fruity/apple were somewhat lower and more variable between harvests. (E)-2-hexen-1-ol, neopentane, p-menth-1-en-9-al, 3-hepten-2-one, (Z)-b-ocimene, (Z)-2-penten-1-ol, 1-methyl-1,4-cyclohexadiene, glucose, fructose and three unknown volatile compounds were identified as key-metabolites involved in the flavor differences between both genotypes and harvests. The complex nature of flavor is exemplified by the observed masking effect of fructose and other sugars on sourness and sourness related metabolites, like citrate. The knowledge obtained from the overall biochemical, sensory and prediction analyses forms a basis for targeted flavor improvement by breeding

Prediction of sweet pepper (Capsicum annuum) flavour over different harvests

To better understand and predict the complex multifactorial trait flavor, volatile and non-volatile components were measured in fresh sweet pepper (Capsicum annuum) fruits throughout the growing season in a diverse panel of 24 breeding lines, hybrids, several cultivated genotypes and one gene bank accession. Biochemical profiles were linked to individual flavor attributes, that were objectively quantified by a trained descriptive expert panel. We used a Random Forest regression approach for prediction of the flavor attributes within and between harvests. Predictions of texture related attributes (juiciness, toughness, crunchiness and stickiness of the skin) and sweetness were good (around 60–65 %in the analyses with the three harvests combined). The predictions of the attributes aroma intensity, sourness and fruity/apple were somewhat lower and more variable between harvests. (E)-2-hexen-1-ol, neopentane, p-menth-1-en-9-al, 3-hepten-2-one, (Z)-b-ocimene, (Z)-2-penten-1-ol, 1-methyl-1,4-cyclohexadiene, glucose, fructose and three unknown volatile compounds were identified as key-metabolites involved in the flavor differences between both genotypes and harvests. The complex nature of flavor is exemplified by the observed masking effect of fructose and other sugars on sourness and sourness related metabolites, like citrate. The knowledge obtained from the overall biochemical, sensory and prediction analyses forms a basis for targeted flavor improvement by breeding