Cosmic Ray Telescope Experiment (CRT), Pioneer 10/11 Program

In May 1996 the electrical power on Pioneer 10 was no longer adequate to support the Cosmic Ray Telescope Experiment (CRT). In March 1997 ground based operations for the mission were terminated. The 25 years of Pioneer 10 were a remarkable voyage of discovery as it ventured into a vast new unexplored region of space. These observations by the Pioneer experiments led in the development of a new discipline of space science - heliospheric physics. For cosmic ray studies it was an incredible era, leading to the identification of new energetic particle populations and processes and initiating the study of the dynamics and large-scale structure and began the study of the dynamics and large-scale structure of the outer heliosphere. A summary of some of the principal scientific findings of the CRT experiment over this period is given in the next section. Even with the cessation of data from the Pioneer 10/11 mission there remained a great deal of scientific analysis and data archiving that required on the order of an additional three years of effort on the part of the CRT team. We have tried to select those tasks where the P10/11 CRT data have an important role to play. Special emphasis is placed on long-term synoptic studies that make use of the extended temporal and spatial coverage of the missions and the full capabilities of the CRT experiment. The major scientific objectives of this study are: (1) A phenomenological study of the modulation process in the heliosphere, thereby laying the foundation for developing a unified model of cosmic ray modulation over a complete 22 year heliomagnetic cycle; (2) These modulation studies and the temporal changes in the cosmic ray intensities also provide information on the large-scale structure and dynamics of the outer heliosphere; (3) use the galactic and anomalous cosmic ray data from Pioneer 10 to obtain a more accurate estimate of the distance to the modulation boundary and to the termination shock; (4) Use the results from (2) and from temporal variations to determine whether significant modulation occurs in the region of the heliosphere; (5)study the acceleration and transport of low energy solar interplanetary energetic particles and their relation to solar activity and interplanetary phenomena

Search for the Heliospheric Termination Shock (TS) and Heliosheath (HS)

Voyager 1 continues to measure the very distant Heliospheric Magnetic Field (HMF) beyond 95 AU at ~35 North latitude. The MAG instrument data covers more than a full 22 years solar magnetic cycle. The magnitude of the observed HMF is well described, on average, by Parker's Archimedean spiral structure if due account is made for time variations of the source field strength and solar wind velocity. The V1 magnetic field observations do not provide any evidence for a field increase associated with entry into a subsonic solar wind region, such as the heliosheath is expected to be, nor an exit from this regime. We see no evidence for crossing of the Termination Shock (TS) as has been reported at ~85 AU by the LECP instrument. Merged Interaction Regions are identified by an increased HMF and associated decreases in the flux of >70 MeV/nuc cosmic rays which are then followed by a flux recovery. This CR-B relationship has been identified in V1 data and studied since 1982 when V1 was at 11 AU. The variance of HMF, a direct measure of the energy**1/2 in the HMF fluctuations, shows no significant changes associated with the alleged TS crossings in 2002–2003. Thus, the absence of any HMF increase at the entry into the heliosheath appears not to be due to the onset of mesoscale turbulence as proposed by Fisk. The TS has yet to be directly observed in-situ by the V1 MAG experiment in data through 2003

Role of interferon‐γ and inflammatory monocytes in driving colonic inflammation during acute Clostridium difficile infection in mice

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/136491/1/imm12700.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/136491/2/imm12700_am.pd

A high-throughput de novo sequencing approach for shotgun proteomics using high-resolution tandem mass spectrometry

<p>Abstract</p> <p>Background</p> <p>High-resolution tandem mass spectra can now be readily acquired with hybrid instruments, such as LTQ-Orbitrap and LTQ-FT, in high-throughput shotgun proteomics workflows. The improved spectral quality enables more accurate <it>de novo </it>sequencing for identification of post-translational modifications and amino acid polymorphisms.</p> <p>Results</p> <p>In this study, a new <it>de novo </it>sequencing algorithm, called Vonode, has been developed specifically for analysis of such high-resolution tandem mass spectra. To fully exploit the high mass accuracy of these spectra, a unique scoring system is proposed to evaluate sequence tags based primarily on mass accuracy information of fragment ions. Consensus sequence tags were inferred for 11,422 spectra with an average peptide length of 5.5 residues from a total of 40,297 input spectra acquired in a 24-hour proteomics measurement of <it>Rhodopseudomonas palustris</it>. The accuracy of inferred consensus sequence tags was 84%. According to our comparison, the performance of Vonode was shown to be superior to the PepNovo v2.0 algorithm, in terms of the number of <it>de novo </it>sequenced spectra and the sequencing accuracy.</p> <p>Conclusions</p> <p>Here, we improved <it>de novo </it>sequencing performance by developing a new algorithm specifically for high-resolution tandem mass spectral data. The Vonode algorithm is freely available for download at <url>http://compbio.ornl.gov/Vonode</url>.</p

129-derived Strains of Mice Are Deficient in DNA Polymerase ι and Have Normal Immunoglobulin Hypermutation

Recent studies suggest that DNA polymerase η (polη) and DNA polymerase ι (polι) are involved in somatic hypermutation of immunoglobulin variable genes. To test the role of polι in generating mutations in an animal model, we first characterized the biochemical properties of murine polι. Like its human counterpart, murine polι is extremely error-prone when catalyzing synthesis on a variety of DNA templates in vitro. Interestingly, when filling in a 1 base-pair gap, DNA synthesis and subsequent strand displacement was greatest in the presence of both pols ι and η. Genomic sequence analysis of Poli led to the serendipitous discovery that 129-derived strains of mice have a nonsense codon mutation in exon 2 that abrogates production of polι. Analysis of hypermutation in variable genes from 129/SvJ (Poli−/−) and C57BL/6J (Poli+/+) mice revealed that the overall frequency and spectrum of mutation were normal in polι-deficient mice. Thus, either polι does not participate in hypermutation, or its role is nonessential and can be readily assumed by another low-fidelity polymerase

Interleukin‐22 and CD160 play additive roles in the host mucosal response to Clostridium difficile infection in mice

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/110834/1/imm12414.pd

A Powerful AGN Outburst in RBS 797

Utilizing $\sim 50$ ks of Chandra X-ray Observatory imaging, we present an analysis of the intracluster medium (ICM) and cavity system in the galaxy cluster RBS 797. In addition to the two previously known cavities in the cluster core, the new and deeper X-ray image has revealed additional structure associated with the active galactic nucleus (AGN). The surface brightness decrements of the two cavities are unusually large, and are consistent with elongated cavities lying close to our line-of-sight. We estimate a total AGN outburst energy and mean jet power of $\approx 3 - 6 \times 10^{60}$ erg and $\approx 3 - 6 \times 10^{45}$ erg s$^{-1}$, respectively, depending on the assumed geometrical configuration of the cavities. Thus, RBS 797 is apparently among the the most powerful AGN outbursts known in a cluster. The average mass accretion rate needed to power the AGN by accretion alone is $\sim 1 M_{\odot}$ yr$^{-1}$. We show that accretion of cold gas onto the AGN at this level is plausible, but that Bondi accretion of the hot atmosphere is probably not. The BCG harbors an unresolved, non-thermal nuclear X-ray source with a bolometric luminosity of $\approx 2 \times 10^{44}$ erg s$^{-1}$. The nuclear emission is probably associated with a rapidly-accreting, radiatively inefficient accretion flow. We present tentative evidence that star formation in the BCG is being triggered by the radio jets and suggest that the cavities may be driving weak shocks ($M \sim 1.5$) into the ICM, similar to the process in the galaxy cluster MS 0735.6+7421.Comment: Accepted to ApJ; 20 pages, 11 low-resolution figure

Galactic cosmic rays in the distant heliosphere

The small flotilla of spacecraft: Pioneers 10 and 11 and Voyagers 1 and 2 (V1 and V2) that have traveled from 1 AU to the distant heliosphere continue the quest of Victor Hess to understand the nature of this radiation that comes to us from beyond the confines of our solar system. At this time V1 and V2 are traveling deeper into the heliosheath and approaching its outer boundary - the heliopause. In the heliosheath the intensity of 2.5 - 60 MeV GCR electrons has risen significantly above detector background levels and provides an important new diagnostic tool for exploring cosmic ray transport in this previously unexplored region of space. Over the past seven months the intensity of GCR ions and electrons at V1 have remained constant after a steady, 5.5 year exponential increase whose rate varied with particle species. Is this an indication that V1 is approaching the heliopause

Aspiration Before Tissue Filler—An Exercise in Futility and Unsafe Practice

Background: Aesthetic physicians rely on certain anecdotal beliefs regarding the safe practice of filler injections. These include a presumed safety advantage of bolus injection after a negative aspiration. Objectives: The authors sought to review and summarize the published literature on inadvertent intravascular injection of hyaluronic acid and to investigate whether the technique of aspiration confers any safety to the practitioner and the patient. Methods: Pertinent literature was analyzed and the current understanding of the safety of negative and positive aspiration outlined. Results: The available studies demonstrate that aspiration cannot be relied on and should not be employed as a safety measure. It is safer to adopt injection techniques that avoid injecting an intravascular volume with embolic potential than utilize an unreliable test to permit a risky injection. Conclusions: To prevent intravascular injection, understanding "injection anatomy"and injection plane and techniques such as slow, low-pressure injection are important safety measures. Assurance of safety when delivering a bolus after negative aspiration does not appear to be borne out by the available literature. If there is any doubt about the sensitivity or reliability of a negative aspiration, there is no role for its utilization. Achieving a positive aspiration would just defer the risk to the next injection location where a negative aspiration would then be relied on