Enforced limb disuse strongly disrupts the cortical networks that are involved in sensorimotor activities. This disruption causes a cortical reorganization that may be functionally maladaptive. In this study, we used functional magnetic resonance imaging (fMRI) to investigate whether it is possible to prevent this reorganization by compensating for the lack of actual kinesthetic perception with illusory movements induced by "neuromimetic" proprio-tactile feedback that is artificially delivered during immobilization. Sixteen healthy volunteers were equipped for five days with full-hand ortheses that prevented them from performing finger and hand movements but allowed for kinesthetic and tactile sensations. Eight participants received a twice-daily proprio-tactile treatment consisting of the perception of kinesthetic sensations resembling those felt during actual movements generated by miniature vibrators set in the ortheses at the finger and wrist levels. Eight untreated participants received no stimulation. The effects of hand immobilization and treatment were assessed by fMRI during a calibrated voluntary hand movement task and hand tactile stimulation before cast placement and immediately after cast removal. We found that the sensorimotor network was preserved in subjects who underwent this treatment during hand immobilization, while the sensorimotor network of untreated subjects was significantly altered. These findings suggest that sensory feedback and associated movement perception may counteract disuse-induced cortical plastic changes through recruitment of a large part of the cortical network used for actual performed movement. The possibility of guiding cortical plasticity with proprioceptive augmented feedback is potentially relevant for rehabilitation efforts.

During self-paced walking, people with Parkinson's disease maintain anticipatory control during object grasping. However, common functional tasks often include carrying an object while changing step patterns mid-path and maneuvering over obstacles, increasing task complexity and attentional demands. Thus, the present study investigated the effect of Parkinson's disease on the modulation of grasping force changes as a function of gait-related inertial forces. Subjects with Parkinson's disease maintained the ability to scale and to couple over time their grip and inertial forces while walking at irregular step lengths, but were unable to maintain the temporal coupling of grasping forces compared to controls during obstacle crossing. We suggest that this deterioration in anticipatory control is associated with the increased demands of task complexity and attention during obstacle crossing.

Stroke lesions induce not only loss of local neural function, but disruptions in spatially distributed areas. However, it is unknown whether they affect the synchrony of electrical oscillations in neural networks and if changes in network coherence are associated with neurological deficits. This study assessed these questions in a population of patients with subacute, unilateral, ischemic stroke. Spontaneous cortical oscillations were reconstructed from high-resolution electroencephalograms (EEG) with adaptive spatial filters. Maps of functional connectivity (FC) between brain areas were created and correlated with patient performance in motor and cognitive scores. In comparison to age matched healthy controls, stroke patients showed a selective disruption of FC in the alpha frequency range. The spatial distribution of alpha band FC reflected the pattern of motor and cognitive deficits of the individual patient: network nodes that participate normally in the affected functions showed local decreases in FC with the rest of the brain. Interregional FC in the alpha band, but not in delta, theta, or beta frequencies, was highly correlated with motor and cognitive performance. In contrast, FC between contralesional areas and the rest of the brain was negatively associated with patient performance. Alpha oscillation synchrony at rest is a unique and specific marker of network function and linearly associated with behavioral performance. Maps of alpha synchrony computed from a single resting-state EEG recording provide a robust and convenient window into the functionality and organization of cortical networks with numerous potential applications.

Since the invention of the laser more than 50 years ago, scientists have striven to achieve amplification on atomic transitions of increasingly shorter wavelength. The introduction of X-ray free-electron lasers makes it possible to pump new atomic X-ray lasers with ultrashort pulse duration, extreme spectral brightness and full temporal coherence. Here we describe the implementation of an X-ray laser in the kiloelectronvolt energy regime, based on atomic population inversion and driven by rapid K-shell photo-ionization using pulses from an X-ray free-electron laser. We established a population inversion of the Kα transition in singly ionized neon at 1.46 nanometres (corresponding to a photon energy of 849 electronvolts) in an elongated plasma column created by irradiation of a gas medium. We observed strong amplified spontaneous emission from the end of the excited plasma. This resulted in femtosecond-duration, high-intensity X-ray pulses of much shorter wavelength and greater brilliance than achieved with previous atomic X-ray lasers. Moreover, this scheme provides greatly increased wavelength stability, monochromaticity and improved temporal coherence by comparison with present-day X-ray free-electron lasers. The atomic X-ray lasers realized here may be useful for high-resolution spectroscopy and nonlinear X-ray studies.

BACKGROUND: The clinical impact of routine neuropathologic examination of samples from patients with intracerebral hemorrhage (ICH) is unclear. METHODS: Therefore, we evaluated a consecutive series of 378 surgical specimens from patients with ICH concerning demographic data, localization of hemorrhage, preoperative clinical diagnosis and neuropathological diagnosis. RESULTS: Histological examination revealed the putative origin of ICH in 143 cases (37.8%). Vascular pathologies were detected in 127 patients (33.6%), while tumors were identified in 9 patients (2.4%), infarction in 6 patients (1.6%) and abscess in 1 patient (0.3%). Preoperatively, tumor was considered in 65 patients (17.2%), while vascular malformations were supposed in 94 patients (24.9%), infarction in 18 cases (4.8%) and abscess in 3 cases (0.8%). In 198 patients (52.4%) no specific assumption was made. CONCLUSIONS: Comparing preoperative assumptions and histological diagnoses, tumor, vascular malformations and infarctions were clinically overestimated, while arteriolosclerosis and amyloid angiopathy were underestimated. In conclusion, we found that histological findings potentially affecting clinical management and prognosis were obtained in 37.8% of cases. Our data suggest that histopathological examination of intracerebral hemorrhage provides important information for patient management and should be routinely performed.

Alopecia areata (AA) is a common hair loss disorder, which is thought to be a tissue-specific autoimmune disease. Previous research has identified a few AA susceptibility genes, most of which are implicated in autoimmunity. To identify new genetic variants and further elucidate the genetic basis of AA, we performed a genome-wide association study using the strategy of pooled DNA genotyping (729 cases, 656 controls). The strongest association was for variants in the HLA region, which confirms the validity of the pooling strategy. The selected top 61 single-nucleotide polymorphisms (SNPs) were analyzed in an independent replication sample (454 cases, 1364 controls). Only one SNP outside of the HLA region (rs304650) showed significant association. This SNP was then analyzed in a second independent replication sample (537 cases, 657 controls). The finding was not replicated on a significant level, but showed the same tendency. A combined analysis of the two replication samples was then performed, and the SNP rs304650 showed significant association with P=3.43 × 10(-4)(OR=1.24 (1.10-1.39)). This SNP maps to an intronic region of the SPATA5 (spermatogenesis-associated protein 5) gene on chromosome 4. The results therefore suggest the SPATA5 locus is a new susceptibility locus for AA.

Laser wakefield acceleration of electrons holds great promise for producing ultracompact stages of GeV scale, high-quality electron beams for applications such as x-ray free electron lasers and high-energy colliders. Ultrahigh intensity laser pulses can be self-guided by relativistic plasma waves (the wake) over tens of vacuum diffraction lengths, to give >1  GeV energy in centimeter-scale low density plasmas using ionization-induced injection to inject charge into the wake even at low densities. By restricting electron injection to a distinct short region, the injector stage, energetic electron beams (of the order of 100 MeV) with a relatively large energy spread are generated. Some of these electrons are then further accelerated by a second, longer accelerator stage, which increases their energy to ∼0.5  GeV while reducing the relative energy spread to <5% FWHM.

Aim: Duplication of 7q34 resulting in generation of BRAF-KIAA1549 fusion transcripts is a characteristic event in pilocytic astrocytoma that may also aid distinction from diffuse astrocytic tumours. Since data on BRAF- KIAA1549 fusion transcript status remain mainly limited to children, we aimed to examine the diagnostic value of BRAF-KIAA1549 fusion transcripts across all age groups. Methods: BRAF-KIAA1549 fusion transcript status was examined using reverse transcription polymerase chain reaction (RT-PCR) on formalin fixed paraffin embedded samples of 105 primary pilocytic astrocytomas [median patient age: 17 years (1-74 years)]. Results: Informative results (distinct wildtype BRAF bands detectable) were obtained in 105/124 cases (85%). Fusion transcripts were detected in 53 of cases (51%). They were more often encountered in tumours of infratentorial location [42/67 (63%) vs. 11/38 (29%)] and comprised KIAA1549-Ex16_BRAF-Ex9 (32 cases), KIAA1549-Ex15_BRAF-Ex9 (14 cases) and KIAA1549-Ex16_BRAF-Ex11 (7 cases). Fusion transcripts were present in 79% of tumours diagnosed in the first decade of life, but only in 51% of patients aged 11-20 years, 42% of patients aged 21-30 years, 30% of patients aged 31-40 years and 7% of patients older than 40 years. On multivariate logistic regression analysis the association of fusion transcript status and age was confirmed adjusting for tumour location (P = 0.006). Conclusions: The frequency of BRAF-KIAA1549 fusion transcripts is significantly lower in adult patients with pilocytic astrocytoma, weakening the sensitivity of this specific diagnostic marker in that age group.

Chaos presents a striking and fascinating phenomenon of nonlinear systems. A common aspect of such systems is the presence of feedback that couples the output signal partially back to the input. Feedback coupling can be well controlled in optoelectronic devices such as conventional semiconductor lasers that provide bench-top platforms for the study of chaotic behaviour and high bit rate random number generation. Here we experimentally demonstrate that chaos can be observed for quantum-dot microlasers operating close to the quantum limit at nW output powers. Applying self-feedback to a quantum-dot microlaser results in a dramatic change in the photon statistics wherein strong, super-thermal photon bunching is indicative of random-intensity fluctuations associated with the spiked emission of light. Our experiments reveal that gain competition of few quantum dots in the active layer enhances the influence of self-feedback and will open up new avenues for the study of chaos in quantum systems.

We demonstrate a compact hyperdispersion stretcher and compressor pair that permit chirped-pulse amplification in Nd:YAG. We generate 750 mJ, 0.2 nm FWHM, 10 Hz pulses recompressed to an 8 ps near-transform-limited duration. The dispersion-matched pulse compressor and stretcher impart a chirp of 7300 ps/nm, in a 3 m x 1 m footprint.