Generalized instantons in N = 4 super Yang-Mills theory and spinorial geometry

Using spinorial geometry techniques, we classify the supersymmetric solutions of euclidean ${\cal N}=4$ super Yang-Mills theory. These backgrounds represent generalizations of instantons with nontrivial scalar fields turned on, and satisfy some constraints that bear a similarity with the Hitchin equations, and contain the Donaldson equations as a special subcase. It turns out that these constraints can be obtained by dimensional reduction of the octonionic instanton equations, and may be rephrased in terms of a selfduality-like condition for a complex connection. We also show that the supersymmetry conditions imply the equations of motion only partially.Comment: 29 pages, 3 tables. v2: references added. v3: conclusion extended, version published in JHE

First Ex-Vivo Validation of a Radioguided Surgery Technique with beta- Radiation

Purpose: A radio-guided surgery technique with beta- -emitting radio-tracers was suggested to overcome the effect of the large penetration of gamma radiation. The feasibility studies in the case of brain tumors and abdominal neuro-endocrine tumors were based on simulations starting from PET images with several underlying assumptions. This paper reports, as proof-of-principle of this technique, an ex-vivo test on a meningioma patient. This test allowed to validate the whole chain, from the evaluation of the SUV of the tumor, to the assumptions on the bio-distribution and the signal detection. Methods: A patient affected by meningioma was administered 300 MBq of 90Y-DOTATOC. Several samples extracted from the meningioma and the nearby Dura Mater were analyzed with a beta- probe designed specifically for this radio-guided surgery technique. The observed signals were compared both with the evaluation from the histology and with the Monte Carlo simulation. Results: we obtained a large signal on the bulk tumor (105 cps) and a significant signal on residuals of $\sim$0.2 ml (28 cps). We also show that simulations predict correctly the observed yields and this allows us to estimate that the healthy tissues would return negligible signals (~1 cps). This test also demonstrated that the exposure of the medical staff is negligible and that among the biological wastes only urine has a significant activity. Conclusions: This proof-of-principle test on a patient assessed that the technique is feasible with negligible background to medical personnel and confirmed that the expectations obtained with Monte Carlo simulations starting from diagnostic PET images are correct.Comment: 17 pages, 4 Figs, Accepted by Physica Medic

Gezocht: andere methoden en nieuwe partners: landschapsecologie en WLO

De landschapsecologie is inmiddels een gevestigde wetenschap. Toch gaan de biodiversiteit en de kwaliteit van het landschap in Nederland en Vlaanderen nog steeds achteruit. Kunnen we rnet ons vakgebied dan niet meer positieve invloed hebben op landschapsveranderingen? En als we menen van wel hoe dan? Op die vragen gaat dit artikel i

ANTaging: a Research Protocol for Active Navigation Training with Virtual Reality in Mild Cognitive Impairment

Navigation is a multimodal process that requires the active computation of cognitive and bodily cues along with external environmental information. Indeed, according to the embodied cognition framework, the body and the environment build our cognitive representation of the space. This view is supported by findings in the aging population where the decline of bodily information accounts for the deficits in spatial navigation. Consequently, it is crucial to develop innovative rehabilitation solutions in aging that require the active use of bodily and cognitive processing of the space and its elements. Mild cognitive impairment is a geriatric syndrome considered to be a transitional stage between normal aging and dementia. Consequently, it is a preferred time window to administer cognitive rehabilitation programs that could slow down cognitive deterioration. In the current paper, the ANTaging protocol will be presented in its three-step studies: pilot testing, usability study, and proof-of-concept trial

Herstellung einer kieferorthopädischen Apparatur : die Aktivator-Headgear-Kombination

Zahnfehlstellungen können kieferorthopädisch korrigiert werden. Dazu werden festsitzende und herausnehmbare Apparaturen benötigt. Die Aufgabe des Zahntechnikers ist oft die Herstellung der herausnehmbaren Apparatur. Diese Falldokumentation stellt, neben der ausführlichen Befunddokumentation, step by step die Herstellungsschritte einer Aktivator-Headgear-Kombination dar. Zusätzlich gehen die Autoren auf die werkstoffkundlichen Aspekte der verwendeten Materialien ein