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| 2. |
- Eversmann, D., et al.
(författare)
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New Method for a Continuous Determination of the Spin Tune in Storage Rings and Implications for Precision Experiments
- 2015
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Ingår i: Physical Review Letters. - 0031-9007 .- 1079-7114. ; 115:9
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Tidskriftsartikel (refereegranskat)abstract
- A new method to determine the spin tune is described and tested. In an ideal planar magnetic ring, the spin tune-defined as the number of spin precessions per turn-is given by nu(s) = gamma G (gamma is the Lorentz factor, G the gyromagnetic anomaly). At 970 MeV/c, the deuteron spins coherently process at a frequency of approximate to 120 kHz in the Cooler Synchrotron COSY. The spin tune is deduced from the up-down asymmetry of deuteron-carbon scattering. In a time interval of 2.6 s, the spin tune was determined with a precision of the order 10(-8), and to 1 x 10(-10) for a continuous 100 s accelerator cycle. This renders the presented method a new precision tool for accelerator physics; controlling the spin motion of particles to high precision is mandatory, in particular, for the measurement of electric dipole moments of charged particles in a storage ring.
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| 3. |
- Hempelmann, N., et al.
(författare)
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Phase measurement for driven spin oscillations in a storage ring
- 2018
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Ingår i: Physical Review Accelerators and Beams. - : American Physical Society. - 2469-9888. ; 21:4
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Tidskriftsartikel (refereegranskat)abstract
- This paper reports the first simultaneous measurement of the horizontal and vertical components of the polarization vector in a storage ring under the influence of a radio frequency (rf) solenoid. The experiments were performed at the Cooler Synchrotron COSY in Julich using a vector polarized, bunched 0.97 GeV/c deuteron beam. Using the new spin feedback system, we set the initial phase difference between the solenoid field and the precession of the polarization vector to a predefined value. The feedback system was then switched off, allowing the phase difference to change over time, and the solenoid was switched on to rotate the polarization vector. We observed an oscillation of the vertical polarization component and the phase difference. The oscillations can be described using an analytical model. The results of this experiment also apply to other rf devices with horizontal magnetic fields, such as Wien filters. The precise manipulation of particle spins in storage rings is a prerequisite for measuring the electric dipole moment (EDM) of charged particles.
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| 4. |
- Hempelmann, N., et al.
(författare)
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Locking the Spin Precession in a Storage Ring
- 2017
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Ingår i: Physical Review Letters. - : American Physical Society. - 0031-9007 .- 1079-7114. ; 119:1
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Tidskriftsartikel (refereegranskat)abstract
- This Letter reports the successful use of feedback from a spin polarization measurement to the revolution frequency of a 0.97 GeV= c bunched and polarized deuteron beam in the Cooler Synchrotron (COSY) storage ring in order to control both the precession rate (approximate to 121 kHz) and the phase of the horizontal polarization component. Real time synchronization with a radio frequency (rf) solenoid made possible the rotation of the polarization out of the horizontal plane, yielding a demonstration of the feedback method to manipulate the polarization. In particular, the rotation rate shows a sinusoidal function of the horizontal polarization phase (relative to the rf solenoid), which was controlled to within a 1 standard deviation range of sigma= 0.21 rad. The minimum possible adjustment was 3.7 mHz out of a revolution frequency of 753 kHz, which changes the precession rate by 26 mrad/s. Such a capability meets a requirement for the use of storage rings to look for an intrinsic electric dipole moment of charged particles.
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| 5. |
- Saleev, A., et al.
(författare)
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Spin tune mapping as a novel tool to probe the spin dynamics in storage rings
- 2017
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Ingår i: Physical Review Accelerators and Beams. - : American Physical Society. - 2469-9888. ; 20:7
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Tidskriftsartikel (refereegranskat)abstract
- Precision experiments, such as the search for electric dipole moments of charged particles using storage rings, demand for an understanding of the spin dynamics with unprecedented accuracy. The ultimate aim is to measure the electric dipole moments with a sensitivity up to 15 orders in magnitude better than the magnetic dipole moment of the stored particles. This formidable task requires an understanding of the background to the signal of the electric dipole from rotations of the spins in the spurious magnetic fields of a storage ring. One of the observables, especially sensitive to the imperfection magnetic fields in the ring is the angular orientation of stable spin axis. Up to now, the stable spin axis has never been determined experimentally, and in addition, the JEDI collaboration for the first time succeeded to quantify the background signals that stem from false rotations of the magnetic dipole moments in the horizontal and longitudinal imperfection magnetic fields of the storage ring. To this end, we developed a new method based on the spin tune response of a machine to artificially applied longitudinal magnetic fields. This novel technique, called spin tune mapping, emerges as a very powerful tool to probe the spin dynamics in storage rings. The technique was experimentally tested in 2014 using polarized deuterons stored in the cooler synchrotron COSY, and for the first time, the angular orientation of the stable spin axis at two different locations in the ring has been determined to an unprecedented accuracy of better than 2.8 mu rad.
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| 7. |
- Al-Saffar, Anas, 1969-, et al.
(författare)
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Gastrointestinal motility examined by wireless motility capsule (SmartPill®) and gut hormone profiles in inflammatory bowel diseases : Motility and hormones inIBD
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Background: Inflammatory bowel disease (IBD) is associated with vague gastrointestinal (GI) discomfort even when inflammation is in clinical remission. In Crohn’s disease (CD) and ulcerative colitis (UC) motility disorders have been described throughout the GI tract. In clinics, considerable patient discomfort relates to symtoms of dysmotility (e.g., intestinal cramping, distension or diarrhea), which present in active and inactive disease. Treatment requires diagnostic methods to identify pathologies throughout the gut during meals while also evaluating gut peptide hormone changes.Methods: SmartPill® wireless motility capsule (WMC) technique to identify pH and motility derangements along the GI tract. pH, luminal pressure, transit time and prandial peptide hormone changes were compared between either 10 CD patients or 10 UC patients relative 20 age- and sex-matched healthy controls.Results: Motility index was significantly reduced in the stomach and contraction frequency and peak pressures were reduced in CD. Small bowel motility index was reduced in UC. In CD, meal responses of ghrelin, GIP, PYY and leptin, and to a lesser extent GLP-1, showed elevated plasma levels. In UC, ghrelin, GIP and GLP-1, but not PYY and leptin were elevated. Neither had a clear relationship to the motility discrepancies.Conclusion: Enhanced endocrine meal responses may be a cause or result of motility disturbances in IBD, but cannot be broken down by individual peptides. These observations potentially give pathophysiological explanations for GI disturbances in IBD, opening the possibility for pharmacological treatment.
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| 8. |
- Al-Saffar, Anas, 1969-, et al.
(författare)
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Parallel Changes in Harvey-Bradshaw Index, TNFα, and Intestinal Fatty Acid Binding Protein in Response to Infliximab in Crohn’s Disease
- 2017
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Ingår i: Gastroenterology Research and Practice. - Egypt : Hindawi Publishing Corporation. - 1687-6121 .- 1687-630X. ; , s. 1-8
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Tidskriftsartikel (refereegranskat)abstract
- Intestinal fatty acid binding protein (I-FABP) indicates barrier integrity. Aims: determine if I-FABP is elevated in active Crohn's disease (CD) and if I-FABP parallels anti-TNF alpha antibody (infliximab) induced lowering of TNF alpha and Harvey-Bradshaw Index (HBI) as potential indicator of mucosal healing. I-FABP distribution along human gut was determined. Serum from 10 CD patients collected during first three consecutive infliximab treatments with matched pretreatment and follow-up samples one week after each treatment and corresponding HBI data were analyzed. I-FABP reference interval was established from 31 healthy subjects with normal gut permeability. I-FABP and TNF alpha were measured by ELISA; CRP was measured by nephelometry. Healthy tissue was used for I-FABP immunohistochemistry. Pretreatment CD patient TNF alpha was 1.6-fold higher than in-house reference interval, while I-FABP was 2.5-fold higher, which lowered at follow-ups. Combining all 30 infusion/follow-up pairs also revealed changes in I-FABP. HBI followed this pattern; CRP declined gradually. I-FABP was expressed in epithelium of stomach, jejunum, ileum, and colon, with the highest expression in jejunum and ileum. I-FABP is elevated in active CD with a magnitude comparable to TNF alpha. Parallel infliximab effects on TNF alpha, HBI, and I-FABP were found. I-FABP may be useful as an intestine selective prognostic marker in CD.
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| 9. |
- Coletti, C., et al.
(författare)
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Surface studies of hydrogen etched 3C-SiC(001) on Si(001)
- 2007
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Ingår i: Applied Physics Letters. - : American Institute of Physics (AIP). - 0003-6951 .- 1077-3118. ; 91:6, s. 061914-
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Tidskriftsartikel (refereegranskat)abstract
- Themorphology and structure of 3C-SiC(001) surfaces, grown on Si(001) andprepared via hydrogen etching, are studied using atomic force microscopy(AFM), low-energy electron diffraction (LEED), and Auger electron spectroscopy (AES).On the etched samples, flat surfaces with large terraces andatomic steps are revealed by AFM. In ultrahigh vacuum asharp LEED pattern with an approximate (5×1) periodicity is observed. AES studies reveal a “bulklike” composition up to the nearsurface region and indicate that an overlayer consisting of aweakly bound silicon oxide monolayer is present.
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| 10. |
- Diaz Tartera, Hetzel O., et al.
(författare)
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[Not Available].
- 2016
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Ingår i: Läkartidningen. - 0023-7205 .- 1652-7518. ; 113
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Tidskriftsartikel (refereegranskat)abstract
- The wireless motility-recording capsule, "SmartPill", is an ingested one-time use electronic capsule that measures gastrointestinal luminal pressure, pH and temperature along the whole gastrointestinal tract. The pH profile and the pressure patterns define the time at which the capsule moves from the stomach to the duodenum and from the ileum to the caecum, whereas changes in temperature define the times of ingestion and expulsion. The recordings from the wireless motility capsule are sent from a radio transmitter in the capsule to a receiver carried around the waist. Wireless motility recordings have several advantages over imaging and manometry that have been used previously. Primarily the simplicity by which motility recordings are done, as well as the tolerability for the patient and limited need of assistance are valuable aspects. The wireless motility capsule provides standardized measures of transit with relevant normal values for the clinical work-up of patients with motility disturbances.
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