Electron impact fragmentation of cytosine: partial ionization cross sections for positive fragments

We have measured mass spectra for positive ions produced by low-energy electron impact on cytosine using a reflectron time-of-flight mass spectrometer. The electron impact energy has been varied from 0 to 100 eV in steps of 0.5 eV. Ion yield curves of most of the fragment ions have been determined by fitting groups of adjacent peaks in the mass spectra with sequences of normalized Gaussians. The ion yield curves have been normalized by comparing the sum of the ion yields to the average of calculated total ionization cross sections. Appearance energies of the fragment ions have been determined, showing that the fragments 68 u–84 u have appearance energies between 10 and 11 eV, whereas fragments of 55 u and lower mass all have appearance energies above 12 eV. Most of the ion yields of 55 u and smaller show multiple onsets. Several groups of fragments have ion yield curves with nearly the same shape, clearly indicating the relevance of tautomerization in the fragmentation of cytosine

Similar Sensitivity to Ladder Contours in Macular Degeneration Patients and Controls - Table 1

<p><b>AMD</b>: Age-related Macular Degeneration; <b>SG</b>: Stargardt's; <b>c&r</b>: cone and rod dystrophy; <b>NC</b>: North Carolina dystrophy. <b>PRL ecc</b> indicates estimated PRL eccentricity or, in normals, distance of the fixation target from the center of the contour display. <b>loc</b> indicates the location of the target in the visual field, relative to the fovea. <b>MAR</b>–minimum angle of resolution in arcminutes. The last four columns are d' values for performance in completed blocks of the experiment, the same data plotted in <b><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0128119#pone.0128119.g002" target="_blank">Fig 2</a></b> x’s indicate inability to complete a block of trials for a given condition.</p><p>Similar Sensitivity to Ladder Contours in Macular Degeneration Patients and Controls - Table 1 </p

Demographics of the HH patients.

<p>Demographics of the HH patients.</p

Schematic illustrations of the displays used in the study.

<p>(a) The target moves along the horizontal axis of the screen and displays a rightward error from the center of the screen, and (b) the target moves along the vertical axis of the screen and displays a downward error from the center of the screen.</p

HH patients' binocular visual fields.

<p>The binocular visual fields of the seven HH patients are indicated by the white areas. Patients reported no vision in the gray-shaded areas, as measured with a V4e target for Goldmann kinetic perimetry.</p

RMS target position error.

<p>(a) Mean RMS target position error for the horizontal target motion condition against that for the vertical condition for each participant in the two participant groups. Error bars indicate SEs across eight trials. (b) Mean RMS target position error averaged across seven participants for the patient and control groups for the horizontal and the vertical target motion conditions. Error bars are SEs across seven participants. While mean RMS target position error was lower for the horizontal than the vertical target motion condition for the control group, there was no difference in mean RMS error between the two target motion conditions for the patient group.</p

Input position perturbation signal.

<p>Amplitudes () and frequencies () of the seven harmonically independent sinusoids for the input position perturbation .</p

Frequency-response (Bode) plots of control performance.

<p>The top panels present mean gain and the bottom panels mean phase lag, averaged over seven participants, for (a) the HH patient group and (b) the normal vision control group. The rightmost points in each panel indicate mean gain (upper panels) or phase lag (lower panels), averaged across the seven frequencies. Error bars are SEs across seven participants. While mean response gain was higher for the horizontal than the vertical target motion condition for the control group, there was no difference in mean response gain between the two target motion conditions for the patient group. Mean phase lag was lower for the horizontal than the vertical target motion condition for both participant groups.</p

Multiple Modernities of Same-Sex Sexuality in Nigeria

The workshop gathered 26 scholars from 9 ESF member states, Nigeria and the U.S.A. to engage in interdisciplinary dialogue about the social crises to which sexual politics have been linked in Nigeria. While a wide range of topics were discussed in different panels that extended across the three-day duration of the event, questions about the definition, translation and circulation of same-sex vocabularies recurred with specific attention to what exists and takes place outside the purview of the state. A central concern of the participants was to find ways of recognizing and representing same-sex desire and practice in Nigeria and in other parts of the so-called developing world without, at the same time, condoning the unilateral dissemination of Western gender/sexual codes through universal human rights instruments. Some of the workshop participants prioritized the histories of “real people” for exploring the multiplicities of cultures and bodily capacities. Others preferred to make recourse to queer theoretical models as a means of undoing the mechanisms which hinder our ability to perceive human multiplicity. On the whole, it was agreed that African populations have tended to resist the idea that sexuality defines the whole person and that contemporary international LGBT discourses have not sufficiently addressed the complexities of African cultural responses to the sexual question. Other sets of relations that may elude gender/sexual categorization may need to be established in order to promote and protect sexual freedoms in globalizing contexts. A qualified emphasis was placed on “the customary” in Africa as a potential archive of “other ways of doing things”

Subject's natural PSF and Positive and Negative averaged PSFs.

<p>Subject's natural PSF (first row), averaged PSFs of the 10 best positive (middle row) and of the 10 best negative (last row) for each subject. The corresponding coefficients of correlation (r) between Subject's natural PSF and the Averaged Positive and Negative PSFs are shown in each panel.</p