213 research outputs found

    What Do We Like About the IS Field?

    Get PDF
    What do we like about the IS field? This article is based on a panel discussion at the 2009 International Conference on Information Systems (ICIS) held in Phoenix, Arizona. The panel was sponsored by the Senior Scholars’ Consortium. Given the recent enrolment downturn in IS programs and concerns expressed by some about the strength of the field, this article sets out the views of some senior scholars who describe what they like about the IS field

    The activation of neuronal NO synthase is mediated by Gâ protein βγ subunit and the tyrosine phosphatase SHPâ 2

    Full text link
    In CHO cells we had found that CCK positively regulated cell proliferation via the activation of a soluble guanylate cyclase. Here we demonstrate that CCK stimulated a nitric oxide synthase (NOS) activity. The production of NO was involved in the proliferative response elicited by CCK regarding the inhibitory effect of NOS inhibitors Lâ NAME and αâ guanidinoglutaric acid. We identified the NOS activated by the peptide as the neuronal isoform: the expression of the C415A neuronal NOS mutant inhibited both CCKâ induced stimulation of NOS activity and cell proliferation. These two effects were also inhibited after expression of the C459S tyrosine phosphatase SHPâ 2 mutant and the βARKl (495â 689) sequestrant peptide, indicating the requirement of activated SHPâ 2 and Gâ βγ subunit. Kinetic analysis (Western blot after coimmunoprecipitation and specific SHPâ 2 activity) revealed that in response to CCKâ treatment, SHPâ 2 associated to Gâ β1 subunit, became activated, and then dephosphorylated the neuronal NOS through a direct association. These data demonstrate that the neuronal NOS is implicated in proliferative effect evoked by CCK. A novel growth signaling pathway is described, involving the activation of neuronal NOS by dephosphorylation of tyrosyl residues.â Cordelier, P., Estève, J.â P., Rivard, N., Marletta, M., Vaysse, N., Susini, C., Buscail, L. The activation of neuronal no synthase is mediated by Gâ protein βγ subunit and the tyrosine phosphatase SHPâ 2. FASEB J. 13, 2037â 2050 (1999)Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154447/1/fsb2fasebj13142037.pd

    A combined Fourier transform infrared and Cr K-edge X-ray absorption near-edge structure spectroscopy study of the substitution and diffusion of H in Cr-doped forsterite

    Get PDF
    International audienceSingle crystals of synthetic Cr-doped forsterite (Cr:Mg2SiO4) containing both Cr3+ and Cr4+ were partially hydroxylated in piston-cylinder apparatuses at 750-1300 degrees C and pressures from 0.5 to 2.5 GPa, with P(H2O) approximate to P-total. The oxygen fugacity (fO(2)) was buffered by graphite-water, Ni-NiO, Re-ReO2, Fe2O3-Fe3O4 or Ag-Ag2O, and the silica activity (a SiO2) was buffered by powdered forsterite plus either enstatite (Mg2Si2O6), periclase (MgO) or zircon-baddeleyite (ZrSiO4-ZrO2). Profiles of OH content versus distance from the crystal edge were determined using Fourier transform infrared (FTIR) spectroscopy, and profiles of the oxidation state and coordination geometry of Cr were obtained, at the same positions, using K-edge X-ray absorption near-edge structure (XANES) spectroscopy. The techniques are complementary - FTIR spectroscopy images the concentration and nature of O-H bonds, where Cr K-edge XANES spectroscopy shows the effect of the added H on the speciation of Cr already present in the lattice. Profiles of defect-specific absorbance derived from FTIR spectra were fitted to solutions of Fick's second law to derive diffusion coefficients, which yield the Arrhenius relationship for H diffusion in forsterite: log(10)(D) over tilde ([001]) = -2.5 +/- 0.6 + -(224 +/- 12 + 4.0 +/- 2.0 P)/2.303 RT , where (D) over tilde is the measured diffusion coefficient in m(2) s(-1), valid for diffusion parallel to [001] and calibrated between 1000 and 750 degrees C, P and T are in GPa and K, and R is 0.008314 kJK(-1) mol(-1). Diffusivity parallel to [100] is around 1 order of magnitude lower. This is consistent with previous determinations of H diffusion associated with M-site vacancies. The FTIR spectra represent a variety of Cr-bearing hydrous defects, along with defects associated with the pure Mg-Si-O-H system. It is proposed that all of the defects can form by interaction between the dry lattice, including Cr3+ and Cr4+, and fully hydroxylated M-site vacancies. The initial diffusive wave of hydroxylation is associated with neither reduction nor oxidation of Cr but with Cr4+ changing from tetrahedral to octahedral coordination. Superimposed on the H diffusion and concomitant change in Cr4+ site occupancy, but at a slower rate, producing shorter profiles, is reduction of Cr4+ to Cr3+ and potentially of Cr4+ and Cr3+ to Cr2+. In addition, by comparing FTIR data to trace element contents measured by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), constraints can be placed on absorption coefficients used for converting absorbance to H2O contents - our data support either wavenumber- or defect-dependent values of absorption coefficients. We estimate absorption coefficients of between 60 200 and 68 200 L mol(-1) cm(-1) for OH- associated with octahedral Cr3+ and an M-site vacancy and 18 700 to 24 900 L mol(-1) cm(-1) for two OH- associated with octahedrally coordinated Cr4+ and a Si vacancy (i.e. a clinohumite-type point defect)

    Definition of medical event is to be based on the total source strength for evaluation of permanent prostate brachytherapy: A report from the American Society for Radiation Oncology

    Get PDF
    AbstractPurposeThe Nuclear Regulatory Commission deems it to be a medical event (ME) if the total dose delivered differs from the prescribed dose by 20% or more. A dose-based definition of ME is not appropriate for permanent prostate brachytherapy as it generates too many spurious MEs and thereby creates unnecessary apprehension in patients, and ties up regulatory bodies and the licensees in unnecessary and burdensome investigations. A more suitable definition of ME is required for permanent prostate brachytherapy.Methods and MaterialsThe American Society for Radiation Oncology (ASTRO) formed a working group of experienced clinicians to review the literature, assess the validity of current regulations, and make specific recommendations about the definition of an ME in permanent prostate brachytherapy.ResultsThe working group found that the current definition of ME in §35.3045 as “the total dose delivered differs from the prescribed dose by 20 percent or more” was not suitable for permanent prostate brachytherapy since the prostate volume (and hence the resultant calculated prostate dose) is dependent on the timing of the imaging, the imaging modality used, the observer variability in prostate contouring, the planning margins used, inadequacies of brachytherapy treatment planning systems to calculate tissue doses, and seed migration within and outside the prostate. If a dose-based definition for permanent implants is applied strictly, many properly executed implants would be improperly classified as an ME leading to a detrimental effect on brachytherapy. The working group found that a source strength-based criterion, of >20% of source strength prescribed in the post-procedure written directive being implanted outside the planning target volume is more appropriate for defining ME in permanent prostate brachytherapy.ConclusionsASTRO recommends that the definition of ME for permanent prostate brachytherapy should not be dose based but should be based upon the source strength (air-kerma strength) administered

    Kloning Manusia

    Full text link
    In the last few years, very rapid progress in the cloning technology and its development towards human cloning has become a hotly-debated issue. Cloning, which is the process of formation of a number of individuals with the same genetic structure, can be done by means of embryo-splitting method and nuclear transfer. Human cloning through the nuclear transfer method is directed towards two purposes, i.e. reproduction and therapy. The relatively new transgenic technology can be combined with the cloning technique to produce clones with new genes. However, pros and cons arise concerning the development of research on human cloning, particularly cloning for reproductive purposes. Therefore, there is need for a moratorium period before human cloning can be performed in order that solutions for all kinds of problems related to safety and ethics can be found

    Usage Patterns of Stop Smoking Medications in Australia, Canada, the United Kingdom, and the United States: Findings from the 2006–2008 International Tobacco Control (ITC) Four Country Survey

    Get PDF
    Varenicline is a new prescription stop smoking medication (SSM) that has been available in the United States since August 1, 2006, in the United Kingdom and other European Union countries since December 5, 2006, in Canada since April 12, 2007, and in Australia since January 1, 2008. There are few population-based studies that have examined use rates of varenicline and other stop smoking medications. We report data from the ITC Four Country survey conducted with smokers in the US, UK, Canada, and Australia who reported an attempt to quit smoking in past year in the 2006 survey (n = 4,022 participants), 2007 (n = 3,790 participants), and 2008 surveys (n = 2,735 participants) Respondents reported use of various stop smoking medications to quit smoking at each survey wave, along with demographic and smoker characteristics. The self-reported use of any stop smoking medication has increased significantly over the 3 year period in all 4 countries, with the sharpest increase occurring in the United States. Varenicline has become the second most used stop smoking medication, behind NRT, in all 4 countries since being introduced. Between 2006 and 2008, varenicline use rates increased from 0.4% to 21.7% in the US, 0.0% to 14.8% in Canada, 0.0% to 14.5% in Australia, and 0.0% to 4.4% in the UK. In contrast, use of NRT and bupropion remained constant in each country. Males and non-whites were significantly less likely to report using any SSM, while more educated smokers were significantly more likely to use any SSM, including varenicline. Our findings suggest that the introduction of varenicline led to an increase in the number of smokers who used evidence-based treatment during their quit attempts, rather than simply gaining market share at the expense of other medications. From a public health perspective, messages regarding increased success rates among medication users and the relative safety of stop smoking medications should be disseminated widely so as to reach all smokers of all socioeconomic classifications equally
    corecore