6,500 research outputs found
Prehension and perception of size in left visual neglect
Right hemisphere damaged patients with and without left visual neglect, and age-matched controls had objects of various sizes presented within left or right body hemispace. Subjects were asked to estimate the objectsâ sizes or to reach out and grasp them, in order to assess visual size processing in perceptual-experiential and action-based contexts respectively. No impairments of size processing were detected in the prehension performance of the neglect patients but a generalised slowing of movement was observed, associated with an extended deceleration phase. Additionally both patient groups reached maximum grip aperture relatively later in the movement than did controls. For the estimation task it was predicted that the left visual neglect group would systematically underestimate the sizes of objects presented within left hemispace but no such abnormalities were observed. Possible reasons for this unexpected null finding are discussed
Testing the Modern Merger Hypothesis via the Assembly of Massive Blue Elliptical Galaxies in the Local Universe
The modern merger hypothesis offers a method of forming a new elliptical
galaxy through merging two equal-mass, gas-rich disk galaxies fuelling a
nuclear starburst followed by efficient quenching and dynamical stabilization.
A key prediction of this scenario is a central concentration of young stars
during the brief phase of morphological transformation from highly-disturbed
remnant to new elliptical galaxy. To test this aspect of the merger hypothesis,
we use integral field spectroscopy to track the stellar Balmer absorption and
4000\AA\ break strength indices as a function of galactic radius for 12 massive
(), nearby (),
visually-selected plausible new ellipticals with blue-cloud optical colours and
varying degrees of morphological peculiarities. We find that these index values
and their radial dependence correlate with specific morphological features such
that the most disturbed galaxies have the smallest 4000\AA\ break strengths and
the largest Balmer absorption values. Overall, two-thirds of our sample are
inconsistent with the predictions of the modern merger hypothesis. Of these
eight, half exhibit signatures consistent with recent minor merger
interactions. The other half have star formation histories similar to local,
quiescent early-type galaxies. Of the remaining four galaxies, three have the
strong morphological disturbances and star-forming optical colours consistent
with being remnants of recent, gas-rich major mergers, but exhibit a weak,
central burst consistent with forming of their stars. The final
galaxy possesses spectroscopic signatures of a strong, centrally-concentrated
starburst and quiescent core optical colours indicative of recent quenching
(i.e., a post-starburst signature) as prescribed by the modern merger
hypothesis.Comment: 25 pages, 37 figures, accepted to MNRA
âI wish Iâd told themâ: a qualitative study examining the unmet psychosexual needs of prostate cancer patients during follow-up after treatment
<b>Objective</b> To gain insight into patients' experiences of follow-up care after treatment for prostate cancer and identify unmet psychosexual needs.<p></p>
<b>Methods</b> Semi-structured interviews were conducted with a purposive sample of 35 patients aged 59-82 from three UK regions. Partners were included in 18 interviews. Data were analyzed using constant comparison. <p></p>
<b>Results</b> (1) Psychosexual problems gained importance over time, (2) men felt they were rarely invited to discuss psychosexual side effects within follow-up appointments and lack of rapport with health care professionals made it difficult to raise problems themselves, (3) problems were sometimes concealed or accepted and professionals' attempts to explore potential difficulties were resisted by some, and (4) older patients were too embarrassed to raise psychosexual concerns as they felt they would be considered 'too old' to be worried about the loss of sexual function.<p></p>
<b>Conclusion</b> Men with prostate cancer, even the very elderly, have psychosexual issues for variable times after diagnosis. These are not currently always addressed at the appropriate time for the patient.Practice implications Assessments of psychosexual problems should take place throughout the follow-up period, and not only at the time of initial treatment. Further research examining greater willingness or reluctance to engage with psychosexual interventions may be particularly helpful in designing future intervention
The Galaxy Angular Correlation Functions and Power Spectrum from the Two Micron All Sky Survey
We calculate the angular correlation function of galaxies in the Two Micron
All Sky Survey. We minimize the possible contamination by stars, dust, seeing
and sky brightness by studying their cross correlation with galaxy density, and
limiting the galaxy sample accordingly. We measure the correlation function at
scales between 1-18 arcdegs using a half million galaxies. We find a best fit
power law to the correlation function has a slope of 0.76 and an amplitude of
0.11. However, there are statistically significant oscillations around this
power law. The largest oscillation occurs at about 0.8 degrees, corresponding
to 2.8 h^{-1} Mpc at the median redshift of our survey, as expected in halo
occupation distribution descriptions of galaxy clustering.
We invert the angular correlation function using Singular Value Decomposition
to measure the three-dimensional power spectrum and find that it too is in good
agreement with previous measurements. A dip seen in the power spectrum at small
wavenumber k is statistically consistent with CDM-type power spectra. A fit of
CDM-type power spectra to k < 0.2 h Mpc^{-1} give constraints of
\Gamma_{eff}=0.116 and \sigma_8=0.96. This suggest a K_s-band linear bias of
1.1+/-0.2. This \Gamma_{eff} is different from the WMAP CMB derived value. On
small scales the power-law shape of our power spectrum is shallower than that
derived for the SDSS. These facts together imply a biasing of these different
galaxies that might be nonlinear, that might be either waveband or luminosity
dependent, and that might have a nonlocal origin.Comment: 14 pages, 20 figures, to be published in ApJ January 20th, revision
included two new figures, version with high resolution figures can be found
here http::ww
Quasars as Absorption Probes of the J0053+1234 Region
We present UBRI photometry and spectra for 60 quasars found within one square
degree centered on the J0053+1234 region, which has been the subject of the
Caltech Faint Galaxy Redshift Survey. Candidate quasars were selected by their
ultraviolet excess with respect to the stellar locus, and confirmed
spectroscopically. The quasars span a wide range in brightness (17.5<B<21.6)
and redshift (0.43<z<2.38). These new quasars comprise a grid of absorption
probes that can be used to study large-scale structure as well as the
correlation between luminous galaxies, non-luminous halos, and Lyman-alpha
absorbers in the direction of the deep pencil-beam galaxy survey. Spectra of 14
emission line galaxies found using the same technique are also presented.Comment: Accepted for publication in the Astronomical Journal; 29 pages,
including 6 tables and 7 figure
An Iterative Approach to Twisting and Diverging, Type N, Vacuum Einstein Equations: A (Third-Order) Resolution of Stephani's `Paradox'
In 1993, a proof was published, within ``Classical and Quantum Gravity,''
that there are no regular solutions to the {\it linearized} version of the
twisting, type-N, vacuum solutions of the Einstein field equations. While this
proof is certainly correct, we show that the conclusions drawn from that fact
were unwarranted, namely that this irregularity caused such solutions not to be
able to truly describe pure gravitational waves. In this article, we resolve
the paradox---since such first-order solutions must always have singular lines
in space for all sufficiently large values of ---by showing that if we
perturbatively iterate the solution up to the third order in small quantities,
there are acceptable regular solutions. That these solutions become flat before
they become non-twisting tells us something interesting concerning the general
behavior of solutions describing gravitational radiation from a bounded source.Comment: 11 pages, a plain TeX file, submitted to ``Classical and Quantum
Gravity'
Expanding P450 catalytic reaction space through evolution and engineering
Advances in protein and metabolic engineering have led to wider use of enzymes to synthesize important molecules. However, many desirable transformations are not catalyzed by any known enzyme, driving interest in understanding how new enzymes can be created. The cytochrome P450 enzyme family, whose members participate in xenobiotic metabolism and natural products biosynthesis, catalyzes an impressive range of difficult chemical reactions that continues to grow as new enzymes are characterized. Recent work has revealed that P450-derived enzymes can also catalyze useful reactions previously accessible only to synthetic chemistry. The evolution and engineering of these enzymes provides an excellent case study for how to genetically encode new chemistry and expand biology's reaction space
Vacuum type I spacetimes and aligned Papapetrou fields: symmetries
We analyze type I vacuum solutions admitting an isometry whose Killing
2--form is aligned with a principal bivector of the Weyl tensor, and we show
that these solutions belong to a family of type I metrics which admit a group
of isometries. We give a classification of this family and we study the
Bianchi type for each class. The classes compatible with an aligned Killing
2--form are also determined. The Szekeres-Brans theorem is extended to non
vacuum spacetimes with vanishing Cotton tensor.Comment: 19 pages; a reference adde
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