10 research outputs found

    Quasi-elastic polarization-transfer measurements on the deuteron in anti-parallel kinematics

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    We present measurements of the polarization-transfer components in the 2^2H(e,ep)(\vec e,e'\vec p) reaction, covering a previously unexplored kinematic region with large positive (anti-parallel) missing momentum, pmissp_{\rm miss}, up to 220 MeV/c/c, and Q2=0.65Q^2=0.65 (GeV/c)2({\rm GeV}/c)^2. These measurements, performed at the Mainz Microtron (MAMI), were motivated by theoretical calculations which predict small final-state interaction (FSI) effects in these kinematics, making them favorable for searching for medium modifications of bound nucleons in nuclei. We find in this kinematic region that the measured polarization-transfer components PxP_x and PzP_z and their ratio agree with the theoretical calculations, which use free-proton form factors. Using this, we establish upper limits on possible medium effects that modify the bound proton's form factor ratio GE/GMG_E/G_M at the level of a few percent. We also compare the measured polarization-transfer components and their ratio for 2^2H to those of a free (moving) proton. We find that the universal behavior of 2^2H, 4^4He and 12^{12}C in the double ratio (Px/Pz)A(Px/Pz)1H\frac{(P_x/P_z)^A}{(P_x/P_z)^{^1\rm H}} is maintained in the positive missing-momentum region

    Radiation collimation in a thick crystalline undulator

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    With the recent experimental confirmation of the existence of energetic radiation from a Small Amplitude, Small Period (SASP) crystalline undulator [T.N. Wistisen, K.K. Andersen, S. Yilmaz, R. Mikkelsen, J. Lundsgaard Hansen, U.I. Uggerhøj, W. Lauth, H. Backe, Phys. Rev. Lett. 112, 254801 (2014)], the field of specially manufactured crystals, from which specific radiation characteristics can be obtained, has evolved substantially. In this paper we confirm the existence of the crystalline undulator radiation, using electrons of energies of 855 GeV from the MAinzer MIcrotron (MAMI) in a crystal that is approximately 10 times thicker than the previous one. Furthermore, we have measured a significant increase in enhancement, in good agreement with calculations, of the undulator peak by collimation to angles smaller than the natural opening angle of the radiation emission process, 1 /γ

    GLP-2 analog teduglutide significantly reduces need for parenteral nutrition and stool frequency in a real-life setting

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    Background: To evaluate the benefits of teduglutide in a real-life setting, we analyzed the data of 14 patients with short bowel syndrome treated with teduglutide. Additionally, we studied glucagon-like peptide 2 (GLP-2) receptor expression in samples of small intestinal and colonic tissue to provide explanations for clinical observations. Methods: Stool frequency and consistency, sensation of thirst, parental calorie or fluid uptake and the number of days on parenteral support per week were collected for up to 2 years. Quantitative real-time polymerase chain reaction of the GLP-2 receptor in healthy controls was performed to better understand clinical response in different patient subgroups. Results: There was a significant reduction in parenteral support after 24 and 48 weeks (by 11.0 and 36.6%, respectively; p < 0.05). Further major improvements were made in several patients after over 1 year (reduction by 79.3%, p < 0.05). The proportion of patients who reduced parenteral support by at least 20% was 33.3%, 54.5% and 71.3% after 24 weeks, 48 weeks and beyond 1 year, respectively. Patients on daily parenteral support showed late but strong amelioration. The reduction of thirst was the earliest marker for response. While stool consistency increased ( p < 0.01), stool frequency decreased ( p < 0.05) significantly after 12 weeks. This reduction was even more pronounced in patients with colon in continuity. Supporting these clinical observations, we found a stronger physiological expression of the GLP-2 receptor in the colon than in the small intestine. Conclusions: Patients benefit from teduglutide in a real-life setting, but in contrast to randomized, controlled studies reduction of parenteral support took longer. We identified early clinical markers of response, such as stool consistency and frequency as well as sensation of thirst. Clinical and molecular observations support the role of the colon as an important target organ of teduglutide

    Enhanced electromagnetic radiation in oriented scintillating crystals at the 100-MeV and sub-GeV scales

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    Nowadays, it is well known that the electromagnetic interaction between high-energy particles and matter experiences substantial modifications when the latter consists of a crystalline medium and its lattice axes are almost parallel to the input beam direction. In particular, a strong boost to the cross section of bremsstrahlung by electrons and positrons in high-density oriented crystals has been observed in the 1010-to-100 mathrmGeV100~mathrm{GeV} regime. This effect proves particularly appealing when it comes to inorganic scintillators, given the possibility to exploit it for the development of high-performance, ultra-compact electromagnetic calorimeters. This work provides a detailed discussion of the results obtained by probing a PWO (lead tungstate) oriented sample with 120 mathrmGeV/c120~mathrm{GeV}/c electrons and positrons at the CERN North Area: in particular, a comparison between the outcomes obtained with electrons and positrons is made. Moreover, output radiation measurements on a thinner oriented PWO sample have been recently performed in the sub-GeV regime at the MAMI-B facility: an overview on the resulting characterisation is given

    CYP3A5 and ABCB1 genes and hypertension.

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    Hypertension is the first single modifiable cause of disease burden worldwide. Genes encoding proteins that are involved in the metabolism (CYP3A5) and transport (ABCB1) of drugs and hormones might contribute to blood pressure control in humans. Indeed, recent data have suggested that CYP3A5 and ABCB1 gene polymorphisms are associated with blood pressure in the rat as well as in humans. Interestingly, the effects of these genes on blood pressure appear to be modified by dietary salt intake. This review summarizes what is known regarding the relationships of the ABCB1 and CYP3A5 genes with blood pressure, and discusses the potential underlying mechanisms of the association. If the role of these genes in blood pressure control is confirmed in other populations and other ethnic groups, these findings would point toward a new pathway for blood pressure control in humans

    Commissioning of the hypertriton binding energy measurement at MAMI

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    A high-precision hypernuclear experiment has been commissioned at the Mainz Microtron (MAMI) to determine the hypertriton Λ binding energy via decay-pion spectroscopy. The method has been successfully pioneered with 4ΛH studies in the last decade. The experiment makes use of a novel high luminosity lithium target with a length of 45mm while being only 0.75mm thick to keep momentum smearing of the decay pions low. The target-to-beam alignment as well as the observation of the deposited heat is achieved with a newly developed thermal imaging system. Together with a precise beam energy determination via the undulator light interference method a recalibration of the magnetic spectrometers will be done to obtain a statistical and systematic error of about 20 keV. The experiment started in the summer of 2022 and initial optimization studies for luminosity and data quality are presented

    L’habitat et l’occupation des sols à l’âge du Bronze et au début du premier âge du Fer

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    National audienceThe Bronze Age cultures have long been arduous for archaeologists to determine because of their diverse manifestations and tenuous remnants. It took more than 25 years of rescue archaeological research to understand that the Bronze Age is very likely a key period in the emergence of pre-state hierarchical societies and in the construction of our environment. This publication is a first national synthesis, region by region, of a research program still in progress, the “Bronze” national survey. This work of processing and interpreting archaeological and palaeoenvironmental data made it possible to assess the status of rural installations, to measure the ties that unite these spaces to form a network of settlements and to systematize the symbolic appropriation of places by these communities. This work also highlights the place in which natural environments are often considered, wrongfully, as marginal, in the early days of the diversification of socio-economic systems.Les cultures de l’âge du Bronze ont longtemps été ardues à déterminer pour les archéologues tant leurs manifestations sont diverses et leurs vestiges ténus. Il aura fallu plus de 25 ans de recherche archéologique préventive pour comprendre que l’âge du Bronze constitue très probablement une période clé dans l’émergence des sociétés hiérarchisées pré-étatiques et dans la construction de notre environnement.Cet ouvrage est une première synthèse à l’échelle nationale, région par région, d’un programme de recherche toujours en cours, l’enquête nationale Bronze. Ce travail d’exploitation et d’interprétation des données archéologiques et paléoenvironnementales a permis d’apprécier le statut des installations rurales, de mesurer les liens qui unissent ces espaces pour former des réseaux de peuplement et de systématiser l’appropriation symbolique des lieux par ces populations. Il révèle également la place de milieux naturels souvent considérés, à tort, comme marginaux, dans les débuts de la diversification des systèmes socio-économiques
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