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B. This (b + this)
Selected AbstractsSmall bowel hydro-MR imaging for optimized ileocecal distension in Crohn's disease: Should an additional rectal enema filling be performed?JOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 1 2005Waleed Ajaj MD Abstract Purpose To assess the impact of an additional rectal enema filling in small bowel hydro-MRI in patients with Crohn's disease. Materials and Methods A total of 40 patients with known Crohn's disease were analyzed retrospectively: 20 patients only ingested an oral contrast agent (group A), the other 20 subjects obtained an additional rectal water enema (group B). For small bowel distension, a solution containing 0.2% locust bean gum (LBG) and 2.5% mannitol was used. In all patients, a breathhold contrast-enhanced T1w three-dimensional volumetric interpolated breathhold examination (VIBE) sequence was acquired. Comparative analysis was based on image quality and bowel distension as well as signal-to-noise ratio (SNR) measurements. MR findings were compared with those of conventional colonoscopy, as available (N = 25). Results The terminal ileum and rectum showed a significantly higher distension following the rectal administration of water. Furthermore, fewer artifacts were seen within group B. This resulted in a higher reader confidence for the diagnosis of bowel disease, not only in the colon, but also in the ileocecal region. Diagnostic accuracy in diagnosing inflammation of the terminal ileum was 100% in group B; in the nonenema group there were three false-negative diagnoses of terminal ileitis. Conclusion Our data show that the additional administration of a rectal enema is useful in small bowel MRI for the visualization of the terminal ileum. The additional time needed for the enema administration was minimal, and small and large bowel pathologies could be diagnosed with high accuracy. Thus, we suggest that a rectal enema in small bowel MR imaging be considered. J. Magn. Reson. Imaging 2005;22:92,100. © 2005 Wiley-Liss, Inc. [source] Influence of substituent groups at the 3-position on the mass spectral fragmentation pathways of cephalosporinsRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 14 2010Jin Li The structural fragment ions of nine cephalosporins were studied by electrospray ionization quadrapole trap mass spectrometry (Q-Trap MSn) in positive mode. The influence of substituent groups in the 3-position on fragmentation pathway B, an ,-cleavage between the C7C8 single bond, coupled with a [2,4]-trans-Diels-Alder cleavage simultaneously within the six-membered heterocyclic ring, was also investigated. It was found that when the substituent groups were methyl, chloride, vinyl, or propenyl, fragmentations belonging to pathway B were detected; however, when the substituents were heteroatoms such as O, N, or S, pathway B fragmentation was not detected. This suggested that the [M,R3]+ ion, which was produced by the bond cleavage within the substituent group at the 3-position, had a key influence on fragmentation pathway B. This could be attributed to the strong electronegativity of the heteroatoms (O, N, S) that favors the production of the [M,R3]+ ion. Moreover, having the positive charge of the [M,R3]+ ion localized on the nitrogen atom in the 1-position changed the electron density distribution of the heterocyclic structure, which prohibits a [2,4]-reverse-Diels-Alder fragmentation and as a result fragmentation pathway B could not occur. The influence of the substituent group in the 3-position was determined by the intensity ratio (e/d) of ions produced by fragmentation pathway A, a [2,2]-trans-Diels-Alder cleavage within the quaternary lactam ring, including the breaking of the amide bond and the C6C7 single bond (ion d), and fragmentation pathway B (ion e). The results indicate that the electronegativity of the substituent group was a key influencing factor of pathway B fragmentation intensity, because the intensity ratio (e/d) is higher for a chlorine atom, a vinyl, or a propenyl group than that of a methyl group. This study provided some theoretical basis for the identification of cephalosporin antibiotics and structural analysis of related substances in drugs. Copyright © 2010 John Wiley & Sons, Ltd. [source] A review of forecast error covariance statistics in atmospheric variational data assimilation.THE QUARTERLY JOURNAL OF THE ROYAL METEOROLOGICAL SOCIETY, Issue 637 2008I: Characteristics, measurements of forecast error covariances Abstract This article reviews the characteristics of forecast error statistics in meteorological data assimilation from the substantial literature on this subject. It is shown how forecast error statistics appear in the data assimilation problem through the background error covariance matrix, B. The mathematical and physical properties of the covariances are surveyed in relation to a number of leading systems that are in use for operational weather forecasting. Different studies emphasize different aspects of B, and the known ways that B can impact the assimilation are brought together. Treating B practically in data assimilation is problematic. One such problem is in the numerical measurement of B, and five calibration methods are reviewed, including analysis of innovations, analysis of forecast differences and ensemble methods. Another problem is the prohibitive size of B. This needs special treatment in data assimilation, and is covered in a companion article (Part II). Examples are drawn from the literature that show the univariate and multivariate structure of the B -matrix, in terms of variances and correlations, which are interpreted in terms of the properties of the atmosphere. The need for an accurate quantification of forecast error statistics is emphasized. Copyright © 2008 Royal Meteorological Society [source] Serum inhibin B and follicle-stimulating hormone levels as markers in the evaluation of azoospermic men: a comparisonANDROLOGIA, Issue 5 2005A. Halder Summary Inhibin B is a glycoprotein hormone produced mainly by Sertoli cells of the testes in the adult male. It selectively suppresses the secretion of pituitary follicle-stimulating hormone (FSH) and has local paracrine actions in the testes. Its measurement is useful for investigating the role of inhibin B in male gonadal dysfunction. The objective of this study was to investigate the efficacy of serum inhibin B in men with nonobstructive azoospermia in comparison with FSH. Serum concentration of FSH was measured using microparticle enzyme immunoassay, inhibin B by specific solid phase sandwich enzyme-linked immunosorbent assay in men with nonobstructive azoospermia (n = 46) and control fertile men (n = 5). Mean inhibin B and FSH level was 104.6 pg ml,1 and 4.0 mIU ml,1 in control men whereas the value for nonobstructive azoospermic men was 17.06 pg ml,1 and 31.1 mIU ml,1 respectively. Inhibin B and FSH levels were significantly different in azoospermia than controls (P < 0.0001). There were six cases of nonobstructive azoospermia with normal inhibin B. Testicular histology did not find any evidence of spermatogenesis in three cases with normal inhibin B. This demonstrated that inhibin B was not a superior predictor for testicular function in our study. [source] Non-linear redshift distortions: the two-point correlation functionMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 2 2001Somnath Bharadwaj We consider a situation where the density and peculiar velocities in real space are linear, and we calculate ,s, the two-point correlation function in redshift space, incorporating all non-linear effects which arise as a consequence of the map from real to redshift space. Our result is non-perturbative and it includes the effects of possible multi-streaming in redshift space. We find that the deviations from the predictions of the linear redshift distortion analysis increase for the higher spherical harmonics of ,s. While the deviations are insignificant for the monopole ,0, the hexadecapole ,4 exhibits large deviations from the linear predictions. For a COBE normalized , cold dark matter (CDM) power spectrum, our results for ,4 deviate from the linear predictions by a factor of two on the scale of ,10 h,1 Mpc. The deviations from the linear predictions depend separately on f(,) and b. This holds the possibility of removing the degeneracy that exists between these two parameters in the linear analysis of redshift surveys which yields only . We also show that the commonly used phenomenological model, where the non-linear redshift two-point correlation function is calculated by convolving the linear redshift correlation function with an isotropic pair velocity distribution function, is a limiting case of our result. [source] | ||||||||||