Dielectric Properties of Polypropylene Containing Nano-Particles

Peer reviewed: NoNRC publication: Ye

FACT - Time-resolved blazar SEDs

Blazars are highly variable objects and their spectral energy distribution (SED) features two peaks. The emission at low energies is understood, however, the origin of the emission at TeV energies is strongly debated. While snapshots of SEDs usually can be explained with simple models, the evolution of SEDs challenges many models and allows for conclusions on the emission mechanisms. Leptonic models expect a correlation between the two peaks, while hadronic models can accommodate more complex correlations. To study time-resolved SEDs, we set up a target-of-opportunity program triggering high-resolution X-ray observations based on the monitoring at TeV energies by the First G-APD Cherenkov Telescope (FACT). To search for time lags and identify orphan flares, this is accompanied by X-ray monitoring with the Swift satellite. These observations provide an excellent multi-wavelength (MWL) data sample showing the temporal behaviour of the blazar emission along the electromagnetic spectrum. To constrain the origin of the TeV emission, we extract the temporal evolution of the low energy peak from Swift data and calculate the expected flux at TeV energies using a theoretical model. Comparing this to the flux measured by FACT, we want to conclude on the underlying physics. Results from more than five years of monitoring will be discussed.D. Dorner, J. Adam, M.L. Ahnen, D. Baack, M. Balbo, A. Biland, M. Blank, T. Bretz, a, K. Bruegge, M. Bulinski, J. Buss, A. Dmytriiev, S. Einecke, D. Elsaesser, C. Hempfling, T. Herbst, D. Hildebrand, L. Kortmann, L. Linhoff, M. Mahlke, a, K. Mannheim, S.A. Mueller, D. Neise, A. Neronov, M. Noethe, J. Oberkirch, A. Paravac, F. Pauss, W. Rhode, B. Schleicher, F. Schulz, A. Shukla, V. Sliusar, F. Temme, J. Thaele, R. Walter, FACT Collaboration, A. Kreikenbohm, K. Leite

FACT - Highlights from more than Five Years of Unbiased Monitoring at TeV Energies

The First G-APD Cherenkov Telescope (FACT) is monitoring blazars at TeV energies. Thanks to the observing strategy, the automatic operation and the usage of solid state photosensors (SiPM, aka G-APDs), the duty cycle of the instrument has been maximized and the observational gaps minimized. This provides a unprecedented, unbiased data sample of almost 9000~hours of data of which 2375 hours were taken in 2016. An automatic quick look analysis provides results with low latency on a public website. More than 40 alerts have been sent in the last three years based on this. To study the origin of the very high energy emission from blazars simultaneous multi-wavelength and multi-messenger observations are crucial to draw conclusions on the underlying emission mechanisms, e.g. to distinguish between leptonic and hadronic models. FACT not only participates in multi-wavelength studies, correlation studies with other instruments and multi-messenger studies, but also collects time-resolved spectral energy distributions using a target-of-opportunity program with X-ray satellites. At TeV energies, FACT provides an unprecedented, unbiased data sample. Using up to 1850 hours per source, the duty cycle of the sources and the characteristics of flares at TeV energies are studied. In the presentation, the highlights from more than five years of monitoring will be summarized including several flaring activities of Mrk 421, Mrk 501 and 1ES 1959+650.D. Dorner, J. Adam, M.L. Ahnen, D. Baack, M. Balbo, A. Biland, M. Blank, T. Bretz, a, K. Bruegge, M. Bulinski, J. Buss, A. Dmytriiev, S. Einecke, D. Elsaesser, C. Hempfling, T. Herbst, D. Hildebrand, L. Kortmann, L. Linhoff, M. Mahlke, a, K. Mannheim, S.A. Mueller, D. Neise, A. Neronov, M. Noethe, J. Oberkirch, A. Paravac, F. Pauss, W. Rhode, B. Schleicher, F. Schulz, A. Shukla, V. Sliusar, F. Temme, J. Thaele, R. Walte

Primary cilia disappear in rat podocytes during glomerular development

Most tubular epithelial cell types express primary cilia, and mutations of primary-cilium-associated proteins are well known to cause several kinds of cystic renal disease. However, until now, it has been unclear whether mammalian podocytes express primary cilia in vivo. In this study, we determined whether primary cilia are present in the podocytes of rat immature and mature glomeruli by means of transmission electron microscopy of serial ultrathin sections. In immature glomeruli of fetal rats, podocytes express the primary cilia with high percentages at the S-shaped body (88 ± 5%, n = 3), capillary loop (95 ± 4%, n =  4), and maturing glomerulus (76 ± 13%, n = 5) stages. The percentage of ciliated podocytes was significantly lower at the maturing glomerulus stage than at the former two stages. In mature glomeruli of adult rats, ciliated podocytes were not found at all (0 ± 0%, n = 11). These findings indicate that the primary cilia gradually disappear in rat podocytes during glomerular development. Since glomerular filtration rate increases during development, the primary cilia on the podocytes are subjected to a stronger bending force. Thus, the disappearance of the primary cilia presumably prevents the entry of excessive calcium-ions via the cilium-associated polycystin complexes and the disturbance of intracellular signaling cascades in mature podocytes

Single Molecule Imaging Reveals Differences in Microtubule Track Selection Between Kinesin Motors

Molecular motors differentially recognize and move cargo along discrete microtubule subpopulations in cells, resulting in preferential transport and targeting of subcellular cargoes

The extreme HBL behaviour of Markarian 501 during 2012

A multiwavelength campaign was organized to take place between March and July of 2012. Excellent temporal coverage was obtained with more than 25 instruments, including the MAGIC, FACT and VERITAS Cherenkov telescopes, the instruments on board the Swift and Fermi spacecraft, and the telescopes operated by the GASP-WEBT collaboration. Mrk 501 showed a very high energy (VHE) gamma-ray flux above 0.2 TeV of $\sim$0.5 times the Crab Nebula flux (CU) for most of the campaign. The highest activity occurred on 2012 June 9, when the VHE flux was $\sim$3 CU, and the peak of the high-energy spectral component was found to be at $\sim$2 TeV. This study reports very hard X-ray spectra, and the hardest VHE spectra measured to date for Mrk 501. The fractional variability was found to increase with energy, with the highest variability occurring at VHE, and a significant correlation between the X-ray and VHE bands. The unprecedentedly hard X-ray and VHE spectra measured imply that their low- and high-energy components peaked above 5 keV and 0.5 TeV, respectively, during a large fraction of the observing campaign, and hence that Mrk 501 behaved like an extreme high-frequency- peaked blazar (EHBL) throughout the 2012 observing season. This suggests that being an EHBL may not be a permanent characteristic of a blazar, but rather a state which may change over time. The one-zone synchrotron self-Compton (SSC) scenario can successfully describe the segments of the SED where most energy is emitted, with a significant correlation between the electron energy density and the VHE gamma-ray activity, suggesting that most of the variability may be explained by the injection of high-energy electrons. The one-zone SSC scenario used reproduces the behaviour seen between the measured X-ray and VHE gamma-ray fluxes, and predicts that the correlation becomes stronger with increasing energy of the X-rays

Cytokine preconditioning of engineered cartilage provides protection against interleukin-1 insult

Research reported in this publication was supported in part by the National Institute of Arthritis and Musculoskeletal and Skin Diseases and National Institute of Biomedical Imaging and Bioengineering of the National Institutes of Health under Award Number R01AR60361, R01AR061988, P41EB002520). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. ART was supported by a National Science Foundation Graduate Fellowship

Nerve growth factor induces neurite outgrowth of PC12 cells by promoting Gβγ-microtubule interaction

Background: Assembly and disassembly of microtubules (MTs) is critical for neurite outgrowth and differentiation. Evidence suggests that nerve growth factor (NGF) induces neurite outgrowth from PC12 cells by activating the receptor tyrosine kinase, TrkA. G protein-coupled receptors (GPCRs) as well as heterotrimeric G proteins are also involved in regulating neurite outgrowth. However, the possible connection between these pathways and how they might ultimately converge to regulate the assembly and organization of MTs during neurite outgrowth is not well understood. Results: Here, we report that Gβγ, an important component of the GPCR pathway, is critical for NGF-induced neuronal differentiation of PC12 cells. We have found that NGF promoted the interaction of Gβγ with MTs and stimulated MT assembly. While Gβγ-sequestering peptide GRK2i inhibited neurite formation, disrupted MTs, and induced neurite damage, the Gβγ activator mSIRK stimulated neurite outgrowth, which indicates the involvement of Gβγ in this process. Because we have shown earlier that prenylation and subsequent methylation/demethylation of γ subunits are required for the Gβγ-MTs interaction in vitro, small-molecule inhibitors (L-28 and L-23) targeting prenylated methylated protein methyl esterase (PMPMEase) were tested in the current study. We found that these inhibitors disrupted Gβγ and ΜΤ organization and affected cellular morphology and neurite outgrowth. In further support of a role of Gβγ-MT interaction in neuronal differentiation, it was observed that overexpression of Gβγ in PC12 cells induced neurite outgrowth in the absence of added NGF. Moreover, overexpressed Gβγ exhibited a pattern of association with MTs similar to that observed in NGF-differentiated cells. Conclusions: Altogether, our results demonstrate that βγ subunit of heterotrimeric G proteins play a critical role in neurite outgrowth and differentiation by interacting with MTs and modulating MT rearrangement. Electronic supplementary material The online version of this article (doi:10.1186/s12868-014-0132-4) contains supplementary material, which is available to authorized users