773 research outputs found

    Tracking the mind's image in the brain II: Differential effects of repetitive transcranial magnetic stimulation of the right and left parietal lobe.

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    The functional relevance of brain activity during visuospatial tasks was investigated by combining functional magnetic resonance imaging with unilateral repetitive transcranial magnetic stimulation (rTMS). The cognitive tasks involved visuospatial operations on visually presented and mentally imagined material (“mental clock task”). While visuospatial operations were associated with activation of the intraparietal sulcus region bilaterally, only the group which received rTMS to the right parietal lobe showed an impairment of performance during and immediately after rTMS. This functional parietal asymmetry might indicate a capacity of the right parietal lobe to compensate for a temporary suppression of the left. This is compatible with current theories of spatial hemineglect and constitutes a constraint for models of distributed information processing in the parietal lobes

    Methods for removal of unwanted signals from gravity time-series : comparison using linear techniques complemented with analysis of system dynamics

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    We thanks the participants of the 35th General Assembly of the European Seismological Commission for comments on preliminary results. The authors are grateful to all IGETS contributors, particularly to the station operators and to ISDC/GFZ-Potsdam for providing the original gravity data used in this study. We also thank the developers of ATLANTIDA3.1 and UTide. Part of this work was performed using the ICSMB High Performance Computing Cluster, University of Aberdeen. We also thanks M. Thiel and A. Moura for reviewing a preliminary version and making comments on the methods section and M.A. Ara´ujo for comments on Lyapunov exponents. Funding: A. Valencio is supported by CNPq, Brazil [206246/2014-5]; and received a travel grant from the School of Natural and Computing Sciences, University of Aberdeen [PO2073498], for a presentation including preliminary results.Peer reviewedPostprintPublisher PD

    Choreographies with Secure Boxes and Compromised Principals

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    We equip choreography-level session descriptions with a simple abstraction of a security infrastructure. Message components may be enclosed within (possibly nested) "boxes" annotated with the intended source and destination of those components. The boxes are to be implemented with cryptography. Strand spaces provide a semantics for these choreographies, in which some roles may be played by compromised principals. A skeleton is a partially ordered structure containing local behaviors (strands) executed by regular (non-compromised) principals. A skeleton is realized if it contains enough regular strands so that it could actually occur, in combination with any possible activity of compromised principals. It is delivery guaranteed (DG) realized if, in addition, every message transmitted to a regular participant is also delivered. We define a novel transition system on skeletons, in which the steps add regular strands. These steps solve tests, i.e. parts of the skeleton that could not occur without additional regular behavior. We prove three main results about the transition system. First, each minimal DG realized skeleton is reachable, using the transition system, from any skeleton it embeds. Second, if no step is possible from a skeleton A, then A is DG realized. Finally, if a DG realized B is accessible from A, then B is minimal. Thus, the transition system provides a systematic way to construct the possible behaviors of the choreography, in the presence of compromised principals

    Tight-Binding model for semiconductor nanostructures

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    An empirical scpa3s_cp^3_a tight-binding (TB) model is applied to the investigation of electronic states in semiconductor quantum dots. A basis set of three pp-orbitals at the anions and one ss-orbital at the cations is chosen. Matrix elements up to the second nearest neighbors and the spin-orbit coupling are included in our TB-model. The parametrization is chosen so that the effective masses, the spin-orbit-splitting and the gap energy of the bulk CdSe and ZnSe are reproduced. Within this reduced scpa3s_cp_a^3 TB-basis the valence (p-) bands are excellently reproduced and the conduction (s-) band is well reproduced close to the Γ\Gamma-point, i.e. near to the band gap. In terms of this model much larger systems can be described than within a (more realistic) sp3ssp^3s^*-basis. The quantum dot is modelled by using the (bulk) TB-parameters for the particular material at those sites occupied by atoms of this material. Within this TB-model we study pyramidal-shaped CdSe quantum dots embedded in a ZnSe matrix and free spherical CdSe quantum dots (nanocrystals). Strain-effects are included by using an appropriate model strain field. Within the TB-model, the strain-effects can be artifically switched off to investigate the infuence of strain on the bound electronic states and, in particular, their spatial orientation. The theoretical results for spherical nanocrystals are compared with data from tunneling spectroscopy and optical experiments. Furthermore the influence of the spin-orbit coupling is investigated

    Yours ever (well, maybe): Studies and signposts in letter writing

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    Electronic mail and other digital communications technologies seemingly threaten to end the era of handwritten and typed letters, now affectionately seen as part of snail mail. In this essay, I analyze a group of popular and scholarly studies about letter writing-including examples of pundits critiquing the use of e-mail, etiquette manuals advising why the handwritten letter still possesses value, historians and literary scholars studying the role of letters in the past and what it tells us about our present attitudes about digital communications technologies, and futurists predicting how we will function as personal archivists maintaining every document including e-mail. These are useful guideposts for archivists, providing both a sense of the present and the past in the role, value and nature of letters and their successors. They also provide insights into how such documents should be studied, expanding our gaze beyond the particular letters, to the tools used to create them and the traditions dictating their form and function. We also can discern a role for archivists, both for contributing to the literature about documents and in using these studies and commentaries, suggesting not a new disciplinary realm but opportunities for new interdisciplinary work. Examining a documentary form makes us more sensitive to both the innovations and traditions as it shifts from the analog to the digital; we can learn not to be caught up in hysteria or nostalgia about one form over another and archivists can learn about what they might expect in their labors to document society and its institutions. At one time, paper was part of an innovative technology, with roles very similar to the Internet and e-mail today. It may be that the shifts are far less revolutionary than is often assumed. Reading such works also suggests, finally, that archivists ought to rethink how they view their own knowledge and how it is constructed and used. © 2010 Springer Science+Business Media B.V

    Scanning Transmission X-ray Microscopy with X-ray Fluorescence Detection at the XUV Beamline P04, PETRA III, DESY

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    The presented scanning transmission x-ray microscope (STXM), build on top of our existing modular platform (FlexIX) for high resolution imaging experiments, allows versatile investigations of different samples. The FlexIX endstation allows to switch between a Full Field and a STXM mode. For the STXM mode we use a spatialy resolved detector together with an energy dispersive detector, this allows to investigate the morphology and the chemical or elemental distribution of the sample simultaneous. The combination of the nanoscopy endstation and the XUV beamline P04 results in a powerful tool for investigations of life science samples.BMBF, 05K13UL1, Verbundprojekt 05K2013 - Hochauflösende Bildgebung: Hochauflösende Bildgebung im EUV- und weichen Röntgenbereich bei PETRA III und FLASH. Teilprojekt 1

    Informed decision-making based on a leaflet in the context of prostate cancer screening

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    Objective: We aimed to assess to what extent men make informed choices in the context of prostate cancer screening and how written material contributes to that process. Methods: We developed a leaflet describing prostate cancer screening, and a questionnaire consisting of knowledge, attitude, and intended screening uptake components to assess informed decision-making. The leaflet and questionnaire were pilot-tested among men of the target population, adapted accordingly, and sent to 761 members of an online research panel. We operationalized whether the leaflet was read as spending one minute on the leaflet page and by a self-reported answer of respondents. Results: The response rate was 66% (501/761). The group who read the leaflet (n = 342) correctly answered a knowledge item significantly more often (10.9 versus 8.8; p < 0.001) than those who did not read the leaflet (n = 159), and made more informed choices (73% versus 56%; p = 0.001). There were no significant differences in attitude and intended screening uptake between both groups. Conclusion: Having read the leaflet could be one of the factors associated with increased levels of knowledge and informed decision-making. Practical implications: The results of this study showed that increasing knowledge and supporting informed decision-making with written material are feasible in prostate cancer screenin

    In-vivo somatostatin-receptor expression in small cell lung cancer as a prognostic image biomarker and therapeutic target

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    Background: Given the dismal prognosis of small cell lung cancer (SCLC), novel therapeutic targets are urgently needed. We aimed to evaluate whether SSTR expression, as assessed by positron emission tomography (PET), can be applied as a prognostic image biomarker and determined subjects eligible for peptide receptor radionuclide therapy (PRRT). Methods: A total of 67 patients (26 females; age, 41–80 years) with advanced SCLC underwent SSTR-directed PET/computed tomography (somatostatin receptor imaging, SRI). SRI-avid tumor burden was quantified by maximum standardized uptake values (SUVmax) and tumor-to-liver ratios (T/L) of the most intense SCLC lesion. Scan findings were correlated with progression-free (PFS) and overall survival (OS). In addition, subjects eligible for SSTR-directed radioligand therapy were identified, and treatment outcome and toxicity profile were recorded. Results: On a patient basis, 36/67 (53.7%) subjects presented with mainly SSTR-positive SCLC lesions (>50% lesions positive); in 10/67 patients (14.9%), all lesions were positive. The median SUVmax was found to be 8.5, while the median T/L was 1.12. SRI-uptake was not associated with PFS or OS, respectively (SUVmax vs. PFS, ρ = 0.13 with p = 0.30 and vs. OS, ρ = 0.00 with p = 0.97; T/L vs. PFS, ρ = 0.07 with p = 0.58 and vs. OS, ρ = −0.05 with p = 0.70). PRRT was performed in 14 patients. One patient succumbed to treatment-independent infectious complications immediately after PRRT. In the remaining 13 subjects, disease control was achieved in 5/13 (38.5%) with a single patient achieving a partial response (stable disease in the remainder). In the sub-group of responding patients, PFS and OS were 357 days and 480 days, respectively. Conclusions: SSTR expression as detected by SRI is not predictive of outcome in patients with advanced SCLC. However, it might serve as a therapeutic target in selected patient
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