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In their renowned paper (2011, Inventiones Mathematicae 184, 591–627), I. Vollaard and T. Wedhorn defined a stratification on the special fiber of the unitary unramified PEL Rapoport–Zink space with signature $(1,n-1)$. They constructed an isomorphism between the closure of a stratum, called a closed Bruhat–Tits stratum, and a Deligne–Lusztig variety which is not of classical type. In this paper, we describe the $\ell $-adic cohomology groups over $\overline {{\mathbb Q}_{\ell }}$ of these Deligne–Lusztig varieties, where $\ell \not = p$. The computations involve the spectral sequence associated with the Ekedahl–Oort stratification of a closed Bruhat–Tits stratum, which translates into a stratification by Coxeter varieties whose cohomology is known. Eventually, we find out that the irreducible representations of the finite unitary group which appear inside the cohomology contribute to only two different unipotent Harish-Chandra series, one of them belonging to the principal series.
Gray matter (GM) ‘pseudoatrophy’ is well-documented in patients with anorexia nervosa (AN), but changes in white matter (WM) are less well understood. Here we investigated the dynamics of microstructural WM brain changes in AN patients during short-term weight restoration in a combined longitudinal and cross-sectional study design.
Methods
Diffusion-weighted images were acquired in young AN patients before (acAN-Tp1, n = 56) and after (acAN-Tp2, n = 44) short-term weight restoration as well as in age-matched healthy controls (HC, n = 60). Images were processed using Tract-Based-Spatial-Statistics to compare fractional anisotropy (FA) across groups and timepoints.
Results
In the cross-sectional comparison, FA was significantly reduced in the callosal body in acAN-Tp1 compared with HC, while no differences were found between acAN-Tp2 and HC. In the longitudinal arm, FA increased with weight gain in acAN-Tp2 relative to acAN-Tp1 in large parts of the callosal body and the fornix, while it decreased in the right corticospinal tract.
Conclusions
Our findings reveal that dynamic, bidirectional changes in WM microstructure in young underweight patients with AN can be reversed with brief weight restoration therapy. These results parallel those previously observed in GM and suggest that alterations in WM in non-chronic AN are also state-dependent and rapidly reversible with successful intervention.
Closed-loop medical devices such as brain-computer interfaces are an emerging and rapidly advancing neurotechnology. The target patients for brain-computer interfaces (BCIs) are often severely paralyzed, and thus particularly vulnerable in terms of personal autonomy, decisionmaking capacity, and agency. Here we analyze the effects of closed-loop medical devices on the autonomy and accountability of both persons (as patients or research participants) and neurotechnological closed-loop medical systems. We show that although BCIs can strengthen patient autonomy by preserving or restoring communicative abilities and/or motor control, closed-loop devices may also create challenges for moral and legal accountability. We advocate the development of a comprehensive ethical and legal framework to address the challenges of emerging closed-loop neurotechnologies like BCIs and stress the centrality of informed consent and refusal as a means to foster accountability. We propose the creation of an international neuroethics task force with members from medical neuroscience, neuroengineering, computer science, medical law, and medical ethics, as well as representatives of patient advocacy groups and the public.
In this paper we present a microfabricated SiC based alternative to glass-fiber optogenetic stimulation. The glass fiber system currently used for stimulation has numerous drawbacks. First, the very presence of glass can evoke an immune response in cortical tissue that can impede the light-to-neuron optical interface. This glial scarring of brain tissue effectively lowers the spatial resolution and power output of the system. Second, the fragility of an implanted glass fiber is a problem that has yet to be fully addressed. Using SiC the proposed optical structure will address these problems by significantly lowering the amount glial scarring and astrocytic activity expressed as a result of the implant. In addition, single crystal SiC allows for a flexible device that can move with the surrounding tissue without fracturing. Finally, the current glass fibers tend be single channel devices with a single ended emitter. The proposed microfabricated device will allow for multiple channels, multiple wavelengths of stimulation, and electrical feedback on each channel improving upon the current standard.
Snow accumulation and its variability on the East Antarctic plateau are poorly understood due to sparse and regionally confined measurements. We present a 5.3 GHz (C-band) ground-penetrating radar (GPR) profile with a total length of 860 km recovered during the joint Norwegian–US International Polar Year traverse 2007/08. Mean surface mass balance (SMB) over the last 200 years was derived from the GPR data by identifying the volcanic deposition of the Tambora eruption in 1815. It varies between 9.1 and 37.7 kg m−2 a−1 over the profile, with a mean of 23.7 kg m−2 a−1 and a standard deviation of 4.7 kg m−2 a−1. The 200 year SMB estimated is significantly lower than most of the SMB estimates over shorter time periods in this region. This can be partly explained by a SMB minimum in the vicinity of the ice divide. However, it is more likely that a recent increase in SMB observed by several studies is largely responsible for the observed discrepancy.
Based on a ‘Theory of Visual Attention’ (TVA), whole and
partial report of brief letter arrays is presented as a diagnostic tool to
estimate four clinically significant attentional components: perceptual
processing speed, visual working memory storage capacity, efficiency of
top-down control, and spatial distribution of attention. The procedure
used was short enough to be applicable within a standard clinical setting.
Two brain-damaged patients, selected based on lesion location and
neuropsychological test profile, were compared to a control group of 22
healthy subjects. One patient with a right inferior parietal lesion showed
a pattern of non-spatially and spatially lateralized attention deficits
that is typically found in neglect patients. Results from the second
patient supported the decisive role of superior frontal brain structures
for top-down control of visual attention. This double dissociation
supports the hypothesis that, even with a short version of whole and
partial report, valid and meaningful results can be obtained in the
neuropsychological assessment of attention deficits. The potential and
constraints of TVA-based parameter estimation for the clinical application
are discussed. (JINS, 2005, 11, 843–854.)
The present study investigated the usability of whole and partial
report of briefly displayed letter arrays as a diagnostic tool for the
assessment of attentional functions. The tool is based on Bundesen's
(1990, 1998, 2002; Bundesen et al., 2005)
theory of visual attention (TVA), which assumes four separable attentional
components: processing speed, working memory storage capacity, spatial
distribution of attention, and top-down control. A number of studies
(Duncan et al., 1999; Habekost & Bundesen, 2003; Peers et al., 2005) have already demonstrated the
clinical relevance of these parameters. The present study was designed to
examine whether (a) a shortened procedure bears sufficient accuracy and
reliability, (b) whether the procedures reveal attentional constructs with
clinical relevance, and (c) whether the mathematically independent
parameters are also empirically independent. In a sample of 35 young
healthy subjects, we found high intraparameter correlations between full-
and short-length tests and sufficient internal consistencies as measured
via a bootstrapping method. The clinical relevance of the TVA parameters
was demonstrated by significant correlations with established clinical
tests measuring similar constructs. The empirical independence of the four
TVA parameters is suggested by nonsignificant or, in the case of
processing speed and working memory storage capacity, only modest
correlations between the parameter values. (JINS, 2005,
11, 832–842.)
The UK Food Standards Agency convened a group of expert scientists to review current research investigating the effect of dietary lipids on vascular function. The workshop highlighted the need for intervention studies to be sufficiently powered for these measures and that they should be corroborated with other, more validated, risk factors for CVD. Work presented at the workshop suggested a beneficial effect of long-chain n-3 PUFA and a detrimental effect of trans fatty acids. The workshop also considered the importance of the choice of study population in dietary intervention studies and that ‘at risk’ subgroups within the general population may be more appropriate than subjects that are unrepresentatively healthy.
Disaster preparedness as developed by civil authorities and hospitals has not adequately addressed the special characteristics of mass casualties from nuclear accidents, as demonstrated during the accident at the Three Mile Island (TMI) Nuclear Power Generating Plant. Experiences gained by the Radiation Emergency Task Force of the Milton S. Hershey Medical Center, established during the TMI incident, have resulted in reexamination of emregency medical services (EMS) systems response, population and hospital evacuation, decontamination procedures, communications, triage and psychologic impact during such an event. From these investigations, it is now possible to restructure disaster protocols to accommodate accidents involving toxic contamination. Although this report primarily deals with nuclear accidents, it is also useful in planning for large-scale biologic or chemical accidents.
This six-volume work, published between 1860 and 1890, contains a selection of documents in Greek which throw light on the history and politics of the Byzantine Empire in the Middle Ages. The editors, Franz Miklosich (1813–91), philosopher, linguist and Slovenian nationalist, and Josef (or Giuseppe) Müller (1823–95), a Greek scholar who also translated many important works by German classical historians into Italian, used as one of their sources the volumes of Greek manuscripts brought back to Vienna by Ogier Ghiselin de Busbecq (1522–92), the Flemish diplomat, herbalist, and travel writer who had acted as Imperial Ambassador to the Sublime Porte. Volume 4 (published in 1871) focuses on texts relating to (and in many cases originally owned by) Orthodox churches and monasteries in Asia Minor and the eastern Mediterranean, including details of the land and possessions with which they were endowed, and of subsequent donations by the Pious.