Covariant actions for models with non-linear twisted self-duality

We describe a systematic way of the generalization, to models with non-linear duality, of the space-time covariant and duality-invariant formulation of duality-symmetric theories in which the covariance of the action is ensured by the presence of a single auxiliary scalar field. It is shown that the duality-symmetric action should be invariant under the two local symmetries characteristic of this approach, which impose constraints on the form of the action similar to those of Gaillard and Zumino and in the non-covariant formalism. We show that the (twisted) self-duality condition obtained from this action upon integrating its equations of motion can always be recast in a manifestly covariant form which is independent of the auxiliary scalar and thus corresponds to the conventional on-shell duality-symmetric covariant description of the same model. Supersymmetrization of this construction is briefly discussed.Comment: 1+21 pages, v2: typos corrected, references adde

Duality Symmetric Actions with Manifest Space-Time Symmetries

We consider a space-time invariant duality symmetric action for a free Maxwell field and an $SL(2,{\bf R})\times SO(6,22)$ invariant effective action describing a low-energy bosonic sector of the heterotic string compactified on a six-dimensional torus. The manifest Lorentz and general coordinate invariant formulation of the models is achieved by coupling dual gauge fields to an auxiliary vector field from an axionic sector of the theory.Comment: 9 pages, LaTeX, no figures, references added, misprints eliminate

BLG-motivated Lagrangian formulation for the chiral two-form gauge field in D=6 and M5-branes

We reveal non-manifest gauge and SO(1,5) Lorentz symmetries in the Lagrangian description of a six-dimensional free chiral field derived from the Bagger-Lambert-Gustavsson model in arXiv:0804.3629 and make this formulation covariant with the use of a triplet of auxiliary scalar fields. We consider the coupling of this self-dual construction to gravity and its supersymmetrization. In the case of the non-linear model of arXiv:0805.2898 we solve the equations of motion of the gauge field, prove that its non-linear field strength is self-dual and find a gauge-covariant form of the non-linear action. Issues of the relation of this model to the known formulations of the M5-brane worldvolume theory are discussed.Comment: 1+30 pages, v2: added subsection on comparison of different chiral-field actions, clarifications and reference

Assessment of Event-Related EEG Power After Single-Pulse TMS in Unresponsive Wakefulness Syndrome and Minimally Conscious State Patients

In patients without a behavioral response, non-invasive techniques and new methods of data analysis can complement existing diagnostic tools by providing a method for detecting covert signs of residual cognitive function and awareness. The aim of this study was to investigate the brain oscillatory activities synchronized by single-pulse transcranial magnetic stimulation (TMS) delivered over the primary motor area in the time\u2013frequency domain in patients with the unresponsive wakefulness syndrome or in a minimally conscious state as compared to healthy controls. A time\u2013frequency analysis based on the wavelet transform was used to characterize rapid modifications of oscillatory EEG rhythms induced by TMS in patients as compared to healthy controls. The pattern of EEG changes in the patients differed from that of healthy controls. In the controls there was an early synchronization of slow waves immediately followed by a desynchronization of alpha and beta frequency bands over the frontal and centro-parietal electrodes, whereas an opposite early synchronization, particularly over motor areas for alpha and beta and over the frontal and parietal electrodes for beta power, was seen in the patients. In addition, no relevant modification in slow rhythms (delta and theta) after TMS was noted in patients. The clinical impact of these findings could be relevant in neurorehabilitation settings for increasing the awareness of these patients and defining new treatment procedures

Skuteczność terapii wśrodowisku wirtualnym wpierwszych 12 miesiącach po udarze mózgu

Background and purpose Reinforced feedback in virtual environment (RFVE) therapy is emerging as an innovative method in rehabilitation, which may be advantageous in the treatment of the affected arm after stroke. The purpose of this study was to investigate the impact of assisted motor training in a virtual environment for the treatment of the upper extremity (UE) after stroke compared to traditional neuromotor rehabilitation (TNR), studying also if differences exist related to the type of stroke (haemorrhagic or ischaemic). Material and methods Eighty patients affected by a stroke (48 ischaemic and 32 haemorrhagic) that occurred at least 1 year before were enrolled. The clinical assessment comprising the Fugl-Meyer UE (F-M UE), modified Ashworth (Bohannon & Smith) and Functional Independence Measure scale (FIM) was administered before and after the treatment. Results A statistically significant difference between RFVE and TNR groups (Mann-Whitney U-test) was observed in the clinical outcomes of F-M UE and FIM (both p < 0.001), but not Ashworth (p = 0.053). The outcomes of F-M UE and FIM improved in the RFVE haemorrhagic group and in the TNR haemorrhagic group with a significant difference between groups (both p < 0.001), but not for Ashworth (p = 0.651). Comparing the RFVE ischaemic group to the TNR ischaemic group, statistically significant differences emerged in F-M UE (p < 0.001), FIM (p < 0.001), and Ashworth (p = 0.036). Conclusions The RFVE therapy in combination with TNR showed better improvements compared to the TNR treatment only. The RFVE therapy combined with the TNR treatment was more effective than the TNR double training, in both post-ischaemic and post-haemorrhagic groups. We observed improvements in both groups of patients: post-haemorrhagic and post-ischaemic stroke after RFVE training.Wstęp i cel pracy Terapia w środowisku wirtualnym (reinforced feedback in virtual environment – RFVE) staje się nowatorską metodą w rehabilitacji, której zastosowanie może mieć korzystny wpływ w leczeniu porażonej kończyny górnej u chorych po udarze mózgu. Celem pracy było zbadanie wpływu terapii RFVE w leczeniu kończyny górnej po udarze mózgu w stosunku do tradycyjnej rehabilitacji neurologicznej (TRN) oraz określenie występowania różnic zależnych od rodzaju udaru mózgu (krwotoczny, niedokrwienny). Materiał i metody Badaniom poddano 80 chorych (48 pacjentów po udarze niedokrwiennym i 32 pacjentów po krwotocznym udarze mózgu) z niedowładem połowiczym w okresie do roku po przebytym udarze mózgu. Funkcje kończyny górnej oceniano na początku i po zakończeniu badania. Ocena kliniczna obejmowała skalę Fugl-Meyer dla kończyn górnych (F-M UE), zmodyfikowaną skalę Ashworth (Bohannon & Smith) i skalę Functional Independence Measure (FIM). Wyniki Zaobserwowano istotne różnice między grupami RFVE i TNR (test U Manna-Whitneya) w ocenie w skalach F-M UE i FIM (p < 0,001 dla obu różnic), nie stwierdzono natomiast różnicy w skali Ashworth (p = 0,053). Wyniki w skali F-M UE i FIM poprawiły się w grupie chorych z udarem krwotocznym po terapii RFVE i TNR z istotną różnicą pomiędzy grupami (p < 0,001 dla obu różnic), nie stwierdzono natomiast różnicy w skali Ashworth (p = 0,651). Istotne różnice odnotowano również, porównując grupę chorych z udarem niedokrwiennym po terapii RFVE oraz po terapii TNR w skalach F-M UE (p < 0,001), FIM (p = 0,001) i Ashworth (p = 0,036). Wnioski Zastosowanie RFVE połączonej z TNR prowadzi do większej poprawy niż leczenie wyłącznie za pomocą TNR. Terapia w środowisku wirtualnym połączona z TNR była skuteczniejsza niż TNR prowadzona dwa razy intensywniej niż zwykle, zarówno u chorych po udarze niedokrwiennym, jak i krwotocznym. Poprawa po RFVE dotyczyła nie tylko chorych po udarze niedokrwiennym, lecz także krwotocznym

On the equivalence of different formulations of the M Theory five--brane

We show that the field equations for the supercoordinates and the self--dual antisymmetric tensor field derived from the recently constructed kappa-invariant action for the M theory five-brane are equivalent to the equations of motion obtained in the doubly supersymmetric geometrical approach at the worldvolume component level.Comment: TeX file, 12 page