The energetic requirements for electron transfer to the conduction band of silver bromide from a series of cyanine dyes have been studied using both picosecond time-resolved and steady state ...fluorescence techniques. The selected dyes exhibit monomeric absorption spectra in the adsorbed state and have excited state donor energies that are calculated to span a range about the conduction band edge of AgBr. Rate constants and yields for these electron transfers were extracted from the picosecond fluorescence lifetime measurements. Yields were also obtained through independent measurements of the steady state fluorescence of these dyes and were correlated with estimates of the free energy of the reaction to depict a threshold for electron transfer with respect to the conduction band of AgBr. The threshold compares well with model curves from electron transfer theory and with literature reports of photographic relative quantum yield measurements on similar monomeric systems at silver halide surfaces. This correlation supports the electron transfer model for spectral sensitization of the silver halides. Contrasts are drawn with the sharp energetic thresholds expected for aggregated dyes.
Picosecond time resolved luminescence was employed for monitoring the decay of electronic excited reactants on the surface of oxide semiconductors. Decay of cresyl violet monomers was determined on ...TiO
2
and on α-Al
2
O
3
by measuring decay curves over a wide range of very low coverages. The decay curves showed a characteristic opposite dependence on coverage on the oxide semiconductor with a low conduction band edge, i.e. TiO
2
, compared to the oxide semiconductor with a high conduction band edge, i.e. α-Al
2
O
3
. The dominating time constant for cresyl violet monomer decay was in the range of 280 ps on TiO
2
and 560 ps on α-Al
2
O
3
. In both cases quenching was attributed to electron transfer.
At room temperature the decay of excited Cd
3
P
2
quantum dot luminescence was faster than 1 ps when the dots were attached to TiO
2
colloidal particles in solution. The ultrafast decay was ascribed to electron injection.
Deep neural networks (DNNs) trained on object recognition provide the best current models of high-level visual cortex. What remains unclear is how strongly experimental choices, such as network ...architecture, training, and fitting to brain data, contribute to the observed similarities. Here, we compare a diverse set of nine DNN architectures on their ability to explain the representational geometry of 62 object images in human inferior temporal cortex (hIT), as measured with fMRI. We compare untrained networks to their task-trained counterparts and assess the effect of cross-validated fitting to hIT, by taking a weighted combination of the principal components of features within each layer and, subsequently, a weighted combination of layers. For each combination of training and fitting, we test all models for their correlation with the hIT representational dissimilarity matrix, using independent images and subjects. Trained models outperform untrained models (accounting for 57% more of the explainable variance), suggesting that structured visual features are important for explaining hIT. Model fitting further improves the alignment of DNN and hIT representations (by 124%), suggesting that the relative prevalence of different features in hIT does not readily emerge from the Imagenet object-recognition task used to train the networks. The same models can also explain the disparate representations in primary visual cortex (V1), where stronger weights are given to earlier layers. In each region, all architectures achieved equivalently high performance once trained and fitted. The models' shared properties—deep feedforward hierarchies of spatially restricted nonlinear filters—seem more important than their differences, when modeling human visual representations.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Psoriasis is a chronic inflammatory skin disorder characterized by hyperproliferative keratinocytes and immune cell infiltration into the skin, often accompanied by itch. Histamine, acting via ...histamine 1–4 receptors, is known to modulate immune responses in the skin and to induce itch. The aim of this study was to test the role of histamine 2 receptors and histamine 4 receptors in the imiquimod-induced psoriasis-like skin inflammation model. BALB/c mice were treated intraperitoneally with amthamine (histamine 2 receptor agonist), JNJ-39758979 (histamine 4 receptor antagonist), a combination of both, or vehicle twice daily in a preventive manner. Imiquimod was applied once daily onto the back skin for 10 consecutive days. Stimulation of histamine 2 receptors and blockade of histamine 4 receptors ameliorated imiquimod-induced skin inflammation. The combination of amthamine and JNJ-39758979 reduced skin inflammation even more, diminished epidermal hyperproliferation, and inhibited spontaneous scratching behaviour. A combination of histamine 2 receptor agonist and histamine 4 receptor antagonists could represent a new strategy for the treatment of psoriasis.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Background
The histamine H4 receptor (H4R) was brought into focus as a new therapeutic target for the treatment of allergic disorders such as atopic dermatitis (AD). H4R antagonists have already been ...tested in several animal models of AD, but these studies have yielded conflicting results.
Material and methods
The development of ovalbumin‐induced AD‐like skin lesions was analysed in H4R−/− mice and in H4R antagonist (JNJ28307474)‐treated mice.
Results
H4R−/− mice showed a clear amelioration of the skin lesions, with a diminished influx of inflammatory cells and a reduced epidermal hyperproliferation at lesional skin sites. H4R−/− mice had a reduced amount of ovalbumin‐specific IgE, a reduced number of splenocytes and lymph node cells with a decreased number of CD4+ T cells. The H4R modulated the cytokine secretion of CD4+ T cells and splenocytes and altered the cellular profile in the lymph nodes. The anti‐inflammatory effect could only partially be mimicked by JNJ28307474 and only when the H4R antagonist was given during sensitization and challenge and not when JNJ28307474 was only given during the provocation phase of the allergic reaction.
Conclusion
The H4R modulates inflammation in a chronic allergic dermatitis setting. However, results of this study indicate that it is necessary to block the H4R during ontogeny and development of the allergic inflammation.
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