Structure–Function Mapping: Variability and Conviction in Tracing Retinal Nerve Fiber Bundles and Comparison to a Computational Model

yesPurpose: We evaluated variability and conviction in tracing paths of retinal nerve fiber bundles (RNFBs) in retinal images, and compared traced paths to a computational model that produces anatomically-customized structure–function maps. Methods: Ten retinal images were overlaid with 24-2 visual field locations. Eight clinicians and 6 naïve observers traced RNFBs from each location to the optic nerve head (ONH), recording their best estimate and certain range of insertion. Three clinicians and 2 naïve observers traced RNFBs in 3 images, 3 times, 7 to 19 days apart. The model predicted 10° ONH sectors relating to each location. Variability and repeatability in best estimates, certain range width, and differences between best estimates and model-predictions were evaluated. Results: Median between-observer variability in best estimates was 27° (interquartile range [IQR] 20°–38°) for clinicians and 33° (IQR 22°–50°) for naïve observers. Median certain range width was 30° (IQR 14°–45°) for clinicians and 75° (IQR 45°–180°) for naïve observers. Median repeatability was 10° (IQR 5°–20°) for clinicians and 15° (IQR 10°–29°) for naïve observers. All measures were worse further from the ONH. Systematic differences between model predictions and best estimates were negligible; median absolute differences were 17° (IQR 9°–30°) for clinicians and 20° (IQR 10°–36°) for naïve observers. Larger departures from the model coincided with greater variability in tracing. Conclusions: Concordance between the model and RNFB tracing was good, and greatest where tracing variability was lowest. When RNFB tracing is used for structure–function mapping, variability should be considered

NuTeV Structure Function Measurement

The NuTeV experiment obtained high statistics samples of neutrino and anti-neutrino charged current events during the 1996-1997 Fermilab fixed target run. The experiment combines sign-selected neutrino and anti-neutrino beams and the upgraded CCFR iron-scintillator neutrino detector. A precision continuous calibration beam was used to determine the muon and hadron energy scales to a precision of 0.7% and 0.43% respectively. The structure functions F_2(x,Q^2) and xF_3(x,Q^2) obtained by fitting the y-dependence of the sum and the difference of the neutrino and anti-neutrino differential cross sections are presented.Comment: Proceedings of the XIII international workshop on Deep Inelastic Scattering DIS 2005, 4 pages, 4 figure

Collagens - structure, function and biosynthesis.

The extracellular matrix represents a complex alloy of variable members of diverse protein families defining structural integrity and various physiological functions. The most abundant family is the collagens with more than 20 different collagen types identified so far. Collagens are centrally involved in the formation of fibrillar and microfibrillar networks of the extracellular matrix, basement membranes as well as other structures of the extracellular matrix. This review focuses on the distribution and function of various collagen types in different tissues. It introduces their basic structural subunits and points out major steps in the biosynthesis and supramolecular processing of fibrillar collagens as prototypical members of this protein family. A final outlook indicates the importance of different collagen types not only for the understanding of collagen-related diseases, but also as a basis for the therapeutical use of members of this protein family discussed in other chapters of this issue

Structure Function Measurement at HERA

Preliminary results on a measurement of the proton structure function F_2 are reported for momentum transfers squared Q^2 between 1.5~GeV^2 and 5000 GeV^2 and for Bjorken x between 5.10^{-5} and 0.32 using data collected by the HERA experiments H1 and ZEUS in 1994. F_2 increases significantly with decreasing x, even in the lowest reachable Q^2 region. The data are well described by a Next to Leading Order QCD fit, and support within the present precision that the rise at low x within this Q^2 range is generated "radiatively" via the DGLAP evolution equations. Prospects for future structure function measurements at HERA are briefly mentioned.Comment: 16 pages, with 7 encapsulated figures sent separatel

Structure function results from H1

New structure function results from H1 are presented. The measurements cover a huge kinematical range for Q^2, the four momentum transfer squared, from 0.35, GeV^2 to 30,000, GeV^2, and for Bjorken x between \sim 5\cdot 10^{-6} and 0.65. At Q^2>100, GeV^2, full HERA, I data have been analyzed. The data are compared with a new QCD analysis. The impact of the HERA, I data on the parton density functions is discussed.Comment: 8 page

Structure Function Measurements at the LHC

Since the current uncertainty on the structure of the proton affects the new physics discovery potential of LHC, the ATLAS collaboration is investigating methods to constrain this uncertainty over the whole LHC kinematic regime. The Standard Model processes such as direct photon, Z, W and inclusive jet productions are optimal candidates for this purpose.Comment: 4 pages, 4 figures, to appear in the proceedings of the PHOTON2005 Conferenc