Arguments against a dominantly hadronic origin of the VHE radiation from the supernova remnant RX J1713-3946

The flux of photons with energies above 1 TeV from the direction of the centre and a cloud in the western part of the nearby southern supernova remnant (SNR) RX J1713.7-3946 is calculated in the ``hadronic scenario'' that aims to explain the intense VHE radiation from this remnant with the decay of \pi_0 pions produced in nuclear collisions. The expected flux from its centre is found to fall short by about factor 40 from the one observed by the HESS collaboration. This discrepancy presents a serious obstacle to the ``hadronic scenario''. The theoretically expected flux from the molecular cloud exceeds the one observed by HESS by at least a factor 3. While the size of this discrepancy might still seem acceptable in the face of various theoretical uncertainties, the result strongly suggests a strict spatial correlation of the cloud with an excess of TeV \gamma radiation. The observational lack of such correlations in the remnant reported by HESS is another counter argument against the hadronic scenario. In combination these arguments cannot be refuted by choosing certain parameters for the total energy or acceleration efficiency of the SNR.Comment: 8 pages, small clarification and one footnote added to the published versio

Structure-Guided Recombination Creates an Artificial Family of Cytochromes P450

Creating artificial protein families affords new opportunities to explore the determinants of structure and biological function free from many of the constraints of natural selection. We have created an artificial family comprising ~3,000 P450 heme proteins that correctly fold and incorporate a heme cofactor by recombining three cytochromes P450 at seven crossover locations chosen to minimize structural disruption. Members of this protein family differ from any known sequence at an average of 72 and by as many as 109 amino acids. Most (>73%) of the properly folded chimeric P450 heme proteins are catalytically active peroxygenases; some are more thermostable than the parent proteins. A multiple sequence alignment of 955 chimeras, including both folded and not, is a valuable resource for sequence-structure-function studies. Logistic regression analysis of the multiple sequence alignment identifies key structural contributions to cytochrome P450 heme incorporation and peroxygenase activity and suggests possible structural differences between parents CYP102A1 and CYP102A2

Chandra Observations of A Galactic Supernova Remnant Vela Jr.: A New Sample of Thin Filaments Emitting Synchrotron X-Rays

A galactic supernova remnant (SNR) Vela Jr. (RX J0852.0$-$4622, G266.6$-$1.2) shows sharp filamentary structure on the north-western edge of the remnant in the hard X-ray band. The filaments are so smooth and located on the most outer side of the remnant. We measured the averaged scale width of the filaments ($w_u$ and $w_d$) with excellent spatial resolution of {\it Chandra}, which are in the order of the size of the point spread function of {\it Chandra} on the upstream side and 49.5 (36.0--88.8) arcsec on the downstream side, respectively. The spectra of the filaments are very hard and have no line-like structure, and were well reproduced with an absorbed power-law model with $\Gamma =$2.67 (2.55--2.77), or a {\tt SRCUT} model with $\nu_{rolloff}$ = 4.3 (3.4--5.3)$\times 10^{16}$ Hz under the assumption of $p=0.3$. These results imply that the hard X-rays are synchrotron radiation emitted by accelerated electrons, as mentioned previously. Using a correlation between a function ${\cal B} \equiv \nu_{rolloff}/w_d^2$ and the SNR age, we estimated the distance and the age of Vela Jr.: the estimated distance and age are 0.33 (0.26--0.50) kpc and 660 (420--1400) years, respectively. These results are consistent with previous reports, implying that ${\cal B}$--age relation may be a useful tool to estimate the distance and the age of synchrotron X-ray emitting SNRs.Comment: 19 pages, 8 figures, ApJ, in pres

Budding yeast Rif1 binds to replication origins and protects DNA at blocked replication forks

We thank Javier Garzon and Vamsi Krishna Gali for discussion and advice on methods, and Takashi Kubota for helpful comments on the manuscript. This work was supported by Cancer Research UK Programme Award A19059 to ADD and SH. KS was supported by Grant‐in‐Aid for Scientific Research on Priority Areas (15H05970 and 15K21761) from Ministry of Education, Culture, Sports, Science and Technology, Japan. Funding Cancer Research UK (CRUK) A19059 Ministry of Education, Culture, Sports, Science and Technology (MEXT) 15H0597015K21761 Data availability ChIP‐Seq data and corresponding input data were submitted to ArrayExpress under accession number E‐MTAB‐6736.Peer reviewedPublisher PD

High-Energy Neutrino Astronomy

Kilometer-scale neutrino detectors such as IceCube are discovery instruments covering nuclear and particle physics, cosmology and astronomy. Examples of their multidisciplinary missions include the search for the particle nature of dark matter and for additional small dimensions of space. In the end, their conceptual design is very much anchored to the observational fact that Nature accelerates protons and photons to energies in excess of $10^{20}$ and $10^{13}$ eV, respectively. The cosmic ray connection sets the scale of cosmic neutrino fluxes. In this context, we discuss the first results of the completed AMANDA detector and the reach of its extension, IceCube. Similar experiments are under construction in the Mediterranean. Neutrino astronomy is also expanding in new directions with efforts to detect air showers, acoustic and radio signals initiated by super-EeV neutrinos.Comment: 9 pages, Latex2e, uses ws-procs975x65standard.sty (included), 4 postscript figures. To appear in Proceedings of Thinking, Observing, and Mining the Universe, Sorrento, Italy, September 200

Search for Sc-K line emission from RX J0852.0--4622 Supernova remnant with Suzaku

We searched for evidence of line emission around 4keV from the northwestern rim of the supernova remnant RX J0852.0-4622 using Suzaku XIS data. Several papers have reported the detection of an emission line around 4.1keV from this region of the sky. This line would arise from K-band fluorescence by Sc, the immediate decay product of 44Ti. We performed spectral analysis for the entire portion of the NW rim of the remnant within the XIS field of view, as well as various regions corresponding to regions of published claims of line emission. We found no line emission around 4.1keV anywhere, and are able to set a restrictive upper limit to the X-ray flux: 1.1x10^-6 s^-1 cm^-2 for the entire field. For every region, our flux upper limit falls below that of the previously claimed detection. Therefore, we conclude that, to date, no definite X-ray line feature from Sc-K emission has been detected in the NW rim of RX J0852.0-4622. Our negative-detection supports the recent claim that RX J0852-4622 is neither young (1700--4000 yr) nor nearby(~750 pc).Comment: Published in PAS

Suzaku X-Ray Imaging and Spectroscopy of Cassiopeia A

Suzaku X-ray observations of a young supernova remnant, Cassiopeia A, were carried out. K-shell transition lines from highly ionized ions of various elements were detected, including Chromium (Cr-Kalpha at 5.61 keV). The X-ray continuum spectra were modeled in the 3.4--40 keV band, summed over the entire remnant, and were fitted with a simplest combination of the thermal bremsstrahlung and the non-thermal cut-off power-law models. The spectral fits with this assumption indicate that the continuum emission is likely to be dominated by the non-thermal emission with a cut-off energy at > 1 keV. The thermal-to-nonthermal fraction of the continuum flux in the 4-10 keV band is best estimated as ~0.1. Non-thermal-dominated continuum images in the 4--14 keV band were made. The peak of the non-thermal X-rays appears at the western part. The peak position of the TeV gamma-rays measured with HEGRA and MAGIC is also shifted at the western part with the 1-sigma confidence. Since the location of the X-ray continuum emission was known to be presumably identified with the reverse shock region, the possible keV-TeV correlations give a hint that the accelerated multi-TeV hadrons in Cassiopeia A are dominated by heavy elements in the reverse shock region.Comment: Publ. Astron. Soc. Japan 61, pp.1217-1228 (2009

Asymptotics and local constancy of characters of p-adic groups

In this paper we study quantitative aspects of trace characters $\Theta_\pi$ of reductive $p$-adic groups when the representation $\pi$ varies. Our approach is based on the local constancy of characters and we survey some other related results. We formulate a conjecture on the behavior of $\Theta_\pi$ relative to the formal degree of $\pi$, which we are able to prove in the case where $\pi$ is a tame supercuspidal. The proof builds on J.-K.~Yu's construction and the structure of Moy-Prasad subgroups.Comment: Proceedings of Simons symposium on the trace formul