Data Fusion for Cross-Domain Real-Time Object Detection on the Edge

We investigate an edge-computing scenario for robot control, where two similar neural networks are running on one computational node. We test the feasibility of using a single object-detection model (YOLOv5) with the benefit of reduced computational resources against the potentially more accurate independent and specialized models. Our results show that using one single convolutional neural network (for object detection and hand-gesture classification) instead of two separate ones can reduce resource usage by almost 50%. For many classes, we observed an increase in accuracy when using the model trained with more labels. For small datasets (a few hundred instances per label), we found that it is advisable to add labels with many instances from another dataset to increase detection accuracy.

On the photovoltaic effect asymmetry in ferroelectrics

Despite symmetrical polarization, the magnitude of a light-induced voltage is known to be asymmetric with respect to poling sign in many photovoltaic (PV) ferroelectrics (FEs). This asymmetry remains unclear and is often attributed to extrinsic effects. We show here for the first time that such an asymmetry can be intrinsic, steaming from the superposition of asymmetries of internal FE bias and electro-piezo-strictive deformation. This hypothesis is confirmed by the observed decrease of PV asymmetry for smaller FE bias. Moreover, the both PV effect and remanent polarization are found to increase under vacuum-induced expansion and to decrease for gas-induced compression, with tens percents tunability. The change in cations positions under pressure is analysed through the first-principle density functional theory calculations. The reported properties provide key insight for FE-based solar elements optimization.

Beneficial traits of grain-residing endophytic communities in wheat with different sensitivity to Pseudomonas syringae

Deep insight into compositional and functional features of endophytic bacterial communities residing in wheat grains opens the way to the use of their plant growth promoting and biocontrol abilities in agricultural biotechnology. The aim of this work was to compare grain-residing endophytes from winter wheat varieties with different sensitivity to Pseudomonas syringae pv. atrofaciens (McCulloch) and to examine their plant-beneficial traits and antagonistic effects. Grain-residing bacteria were isolated from surface-sterilized grains of three wheat varieties sown in Ukraine following a culture-dependent protocol, and were screened for their plant growth promotion (PGP) and antagonistic properties. Bacterial morphotypes were represented by gram-negative rods, endospore-forming bacilli and gram-positive cocci. Different resistance to phytopathogenic pseudomonads was associated with distinctive quantitative and functional features of grain-residing endophytic communities. High resistance to P. syringae was coupled with the prevalence of gram-negative rods in the endophytic community, the highest proportion of endophytic bacteria possessing three PGP activities (phosphate solubilization, nitrogen fixation and production of indolic compounds) simultaneously, and with the most potent antagonistic activity of grain-residing endospore-forming bacilli. In total, five grain-residing isolates, which were obtained from three wheat varieties (two isolates from varieties with medium and high resistance and one – from a low-resistant variety), demonstrated ability to restrain P. syringae pv. atrofaciens (McCulloch) growth. Two isolates (P6 and P10) which were obtained from the high-resistant wheat variety Podolyanka and were assigned to Paenibacillus and Brevibacillus genera according to their biochemical profiling and MS-DS identification, showed the most potent antagonistic effects as indicated by maximum inhibition zone in agar well diffusion assay. These results shed light on the association of the features of grain-residing endophytic bacteria with wheat resistance to phytopathogenic pseudomonads. Isolates from the high-resistant wheat variety can be recommended for grain dressing as plant growth promoting and biocontrol agents for P. syringae pv. atrofaciens (McCulloch).

NMDA receptor antagonists attenuate noxious and nonnoxious colorectal distention-induced Fos expression in the spinal cord and the visceromotor reflex

In the present three-part study, the effects of intrathecally administered N-methyl-D-aspartate (NMDA) receptor antagonists on responses to noxious and innocuous colorectal distention (CRD) were examined. In the first part, a passive-avoidance paradigm was used to confirm that 80 mm Hg CRD is a noxious stimulus since it produced avoidance behavior. Acquisition of this behavior was blocked by the NMDA receptor antagonist D(-)-2-amino-5-phosphonopetanoic acid (APV, 60 nmol, intrathecal). In contrast, 20 mm Hg CRD is an innocuous stimulus since there was no difference in the behavior of these animals compared to nondistended controls. In the second part, the effects of the NMDA receptor antagonist dizocilpine maleate (MK-801, 0-100 nmol, intrathecal) on CRD-induced Fos expression in the lumbosacral spinal cord were examined. Noxious and innocuous CRD induced 98+/-4 and 50+/-2 Fos labeled cells per section per side of the spinal cord, respectively. MK-801 dose-dependently attenuated noxious CRD-induced Fos. Compared to saline, the peak attenuation was 55%. Innocuous CRD-induced Fos was attenuated by 36% following 100 nmol MK-801. In the third part, the effects of APV (0-240 nmol, intrathecal) on the visceromotor reflex were examined. APV dose-dependently attenuated the visceromotor reflex to graded intensities of CRD that went from the innocuous into the noxious range. In separate animals that only received innocuous stimulation, APV dose-dependently attenuated the visceromotor reflex. The magnitude of attenuation was similar for both stimulus paradigms. These data expand upon our previous dorsal horn neuronal recordings which showed that spinal NMDA receptors partially mediate the processing of both noxious and innocuous colorectal stimuli. They further underscore a difference from somatic tissue in the role of NMDA receptors in processing acute or transient visceral stimuli in the absence of tissue injury.

Site-selective dephosphorylation of the platelet-derived growth factor beta-receptor by the receptor-like protein-tyrosine phosphatase DEP-1

Ligand stimulation of PDGF beta-receptors leads to autophosphorylation of the regulatory tyrosine 857 and of tyrosine residues that in their phosphorylated form serve as docking sites for Src homology 2 domain-containing proteins. Regulation of the PDGF beta-receptor by protein-tyrosine phosphatases is poorly understood. We have investigated PDGF beta-receptor dephosphorylation by receptor-like protein-tyrosine phosphatase DEP-1 using a cell line with inducible DEP-1 expression and by characterizing in vitro dephosphorylation of the PDGF beta-receptor and of receptor-derived phosphopeptides by DEP-1. After DEP-1 induction PDGF beta-receptor.DEP-1 complexes and reduced receptor tyrosine phosphorylation were observed. Phosphopeptide analysis of the PDGF beta-receptors from DEP-1-expressing cells and of the receptors dephosphorylated in vitro by DEP-1 demonstrated that dephosphorylation of autophosphorylation sites of the receptor differed and revealed that the regulatory Tyr(P)(857) was not a preferred site for DEP-1 dephosphorylation. When dephosphorylation of synthetic receptor-derived peptides was analyzed, the selectivity was reproduced, indicating that amino acid sequence surrounding the phosphorylation sites is the major determinant of selectivity. This notion is supported by the observation that the poorly dephosphorylated Tyr(P)(562) and Tyr(P)(857), in contrast to other analyzed phosphorylation sites, are surrounded by basic amino acid residues at positions -4 and +3 relative to the tyrosine residue. Our study demonstrates that DEP-1 dephosphorylation of the PDGF beta-receptor is site-selective and may lead to modulation, rather than general attenuation, of signaling.

Phosphorylation site-specific inhibition of platelet-derived growth factor beta-receptor autophosphorylation by the receptor blocking tyrphostin AG1296

The mechanism of action of AG1296, a potent and specific inhibitor of the platelet-derived growth factor (PDGF) receptor tyrosine kinase [Kovalenko, M., Gazit, A., Böhmer, A., Rorsman, Ch., Rönnstrand, L., Heldin, C.-H., Waltenberger, J., Böhmer, F. D., & Levitzki, A. (1994) Cancer Res. 54, 6106-6114] was investigated. This quinoxalin-type tyrphostin neither interferes with PDGF-BB binding to the PDGF beta-receptor nor has any effect on receptor dimerization. Kinetic analysis of the inhibition was carried out using a synthetic peptide substrate (KY751) corresponding to the sequence around tyrosine 751 autophosphorylation site of the PDGF receptor. It revealed purely competitive inhibition vis-à-vis ATP, mixed competitive inhibition vis-a-vis the peptide substrate for the non-activated receptor, and mixed competitive inhibition vis-à-vis both substrates for the activated receptor. Thus, the type of inhibition apparently changes upon receptor activation, indicating conformational changes at the ATP-binding site. The high degree of selectivity for the tyrphostin AG1296 might result from the complex type of interaction with the active center of the receptor as revealed by the kinetic analysis. Dose-response curves for inhibition of the phosphorylation of individual autophosphorylation sites of the PDGF beta-receptor by AG1296 were different, phosphorylation of tyrosine 857 being the most susceptible to inhibition. Thus, phosphorylation of tyrosine 857 in the PDGF receptor kinase domain seems dispensable for partial kinase activation. The findings are discussed in relation to current models of receptor tyrosine kinase activation.

Tyrosine phosphorylation of GSalpha and inhibition of bradykinin-induced activation of the cyclic AMP pathway in A431 cells by epidermal growth factor receptor

An increasing amount of experimental data suggest that cross-talk exists between pathways involving tyrosine kinases and heterotrimeric G proteins. In a previous study, we demonstrated that bradykinin (BK) increases the intracellular accumulation of cAMP in the human epidermoid carcinoma cell line A431 by stimulating adenylate cyclase activity via a stimulatory G protein (Gsalpha) (Liebmann, C., Graness, A., Ludwig, B., Adomeit, A., Boehmer, A., Boehmer, F.-D., Nürnberg, B., and Wetzker, R. (1996) Biochem. J. 313, 109-118). Here, we present several lines of evidence indicating the ability of epidermal growth factor (EGF) to suppress BK-induced activation of the cAMP pathway in A431 cells via tyrosine phosphorylation of Gsalpha. Gsalpha was specifically immunoprecipitated from A431 cells using the anti-alphas antiserum AS 348. Tyrosine phosphorylation of Gsalpha was detectable in EGF-pretreated cells with monoclonal anti-phosphotyrosine antibodies. Additionally, A431 cells were labeled with [32P]orthophosphate in vivo and treated with EGF, and the resolved immunoprecipitates were subjected to amino acid analysis. The results clearly indicate that EGF induces tyrosine phosphorylation of Gsalpha in A431 cells. Treatment of A431 cells with EGF decreased BK-induced cAMP accumulation in intact cells as well as the stimulation of adenylate cyclase by BK, NaF, and guanyl nucleotides, but not by forskolin. Also, EGF treatment abolished both the BK- and isoprenaline-induced stimulation of guanosine 5'-O-(3-[35S]thiotriphosphate) binding to Gsalpha. In contrast, the BK-evoked, Gq-mediated stimulation of inositol phosphate formation in A431 cells was not affected by EGF pretreatment. Thus, EGF-induced tyrosine phosphorylation of Gsalpha is accompanied by a loss of its susceptibility to G protein-coupled receptors and its ability to stimulate adenylate cyclase via guanyl nucleotide exchange. We propose that Gsalpha may represent a key regulatory protein in the cross-talk between the signal transduction pathways of BK and EGF in A431 cells.

Selective platelet-derived growth factor receptor kinase blockers reverse sis-transformation

A novel class of tyrosine kinase blockers represented by the tyrphostins AG1295 and AG1296 is described. These compounds inhibit selectively the platelet-derived growth factor (PDGF) receptor kinase and the PDGF-dependent DNA synthesis in Swiss 3T3 cells and in porcine aorta endothelial cells with 50% inhibitory concentrations below 5 and 1 microM, respectively. The PDGF receptor blockers have not effect on epidermal growth factor receptor autophosphorylation; weak effects on DNA synthesis stimulated by insulin, by epidermal growth factor, or by a combination of both; and over an order of magnitude weaker blocking effect on fibroblast growth factor-dependent DNA synthesis. AG1296 potently inhibits signaling of human PDGF alpha- and beta-receptors as well as of the related stem cell factor receptor (c-Kit) but has no effect on autophosphorylation of the vascular endothelial growth factor receptor KDR or on DNA synthesis induced by vascular endothelial growth factor in porcine aortic endothelial cells. Treatment by AG1296 reverses the transformed phenotype of sis-transfected NIH 3T3 cells but has no effect on src-transformed NIH 3T3 cells or on the activity of the kinase p60c-src(F527) immunoprecipitated from these cells. These potent and selective compounds represent leads for the development of novel agents to combat tumors driven by PDGF or to inhibit PDGF action in other diseases in which PDGF plays a key role, such as restenosis.