Strong impact of light induced conical intersections on the spectrum of diatomic molecules

We show that dressing of diatomic molecules by running laser waves gives rise to conical intersections (CIs). Due to presence of such CIs, the rovibronic molecular motions are strongly coupled. A pronounced impact of the CI on the spectrum of $Na_2$ molecule is demonstrated via numerical calculation for weak and moderate laser intensity, and an experiment is suggested on this basis. The position of the light induced CI and the strength of its non-adiabatic couplings can be chosen by changing the frequency and intensity of the used running laser wave. This offers new possibilities to control the photo-induced rovibronic molecular dynamics.Comment: 4 pages, 7 figure

Short- and long-term joint symbolic dynamics of heart rate and blood pressure in dilated cardiomyopathy

© 2005 IEEE.Autonomic cardiovascular control involves complex interactions of heart rate and blood pressure. In patients with dilated cardiomyopathy (DCM), this control is impaired and parameters for its quantification might be of prognostic importance. In this paper, we introduce methods based on joint symbolic dynamics (JSD) for the enhanced analysis of heart rate and blood pressure interactions. To assess the coarse-grained dynamics beat-to-beat changes of heart rate and blood pressure are encoded in symbol strings. Subsequently, the distribution properties of short symbol sequences (words) as well as the scaling properties of the whole symbol string are assessed. The comparison of joint symbolic heart rate and blood pressure dynamics in DCM (n=75) with those in healthy controls (n=75) showed significant changes. Both, the distribution of words and the scaling properties indicate a loss in heart rate dynamics associated with blood pressure regulation in DCM. In conclusion, the analyses of short- and long-term JSDs provide insights into complex physiological heart rate and blood pressure interactions and furthermore reveal patho-physiological cardiovascular control in DCM.Baumert, M.; Baier, V.; Truebner, S.; Schirdewan, A.; Voss, A

Investigating the impact of feedback update interval on the efficacy of restorative brain–computer interfaces

Restorative brain-computer interfaces (BCIs) have been proposed to enhance stroke rehabilitation. Restorative BCIs are able to close the sensorimotor loop by rewarding motor imagery (MI) with sensory feedback. Despite the promising results from early studies, reaching clinically significant outcomes in a timely fashion is yet to be achieved. This lack of efficacy may be due to suboptimal feedback provision. To the best of our knowledge, the optimal feedback update interval (FUI) during MI remains unexplored. There is evidence that sensory feedback disinhibits the motor cortex. Thus, in this study, we explore how shorter than usual FUIs affect behavioural and neurophysiological measures following BCI training for stroke patients using a single-case proof-of-principle study design. The action research arm test was used as the primary behavioural measure and showed a clinically significant increase (36%) over the course of training. The neurophysiological measures including motor evoked potentials and maximum voluntary contraction showed distinctive changes in early and late phases of BCI training. Thus, this preliminary study may pave the way for running larger studies to further investigate the effect of FUI magnitude on the efficacy of restorative BCIs. It may also elucidate the role of early and late phases of motor learning along the course of BCI training

Coherent strong-field control of multiple states by a single chirped femtosecond laser pulse

We present a joint experimental and theoretical study on strong-field photo-ionization of sodium atoms using chirped femtosecond laser pulses. By tuning the chirp parameter, selectivity among the population in the highly excited states 5p, 6p, 7p and 5f, 6f is achieved. Different excitation pathways enabling control are identified by simultaneous ionization and measurement of photoelectron angular distributions employing the velocity map imaging technique. Free electron wave packets at an energy of around 1 eV are observed. These photoelectrons originate from two channels. The predominant 2+1+1 Resonance Enhanced Multi-Photon Ionization (REMPI) proceeds via the strongly driven two-photon transition $4s\leftarrow\leftarrow3s$, and subsequent ionization from the states 5p, 6p and 7p whereas the second pathway involves 3+1 REMPI via the states 5f and 6f. In addition, electron wave packets from two-photon ionization of the non-resonant transiently populated state 3p are observed close to the ionization threshold. A mainly qualitative five-state model for the predominant excitation channel is studied theoretically to provide insights into the physical mechanisms at play. Our analysis shows that by tuning the chirp parameter the dynamics is effectively controlled by dynamic Stark-shifts and level crossings. In particular, we show that under the experimental conditions the passage through an uncommon three-state "bow-tie" level crossing allows the preparation of coherent superposition states

Proprioceptive feedback facilitates motor imagery-related operant learning of sensorimotor β-band modulation

Motor imagery (MI) activates the sensorimotor system independent of actual movements and might be facilitated by neurofeedback. Knowledge on the interaction between feedback modality and the involved frequency bands during MI-related brain self-regulation is still scarce. Previous studies compared the cortical activity during the MI task with concurrent feedback (MI with feedback condition) to cortical activity during the relaxation task where no feedback was provided (relaxation without feedback condition). The observed differences might, therefore, be related to either the task or the feedback. A proper comparison would necessitate studying a relaxation condition with feedback and a MI task condition without feedback as well. Right-handed healthy subjects performed two tasks, i.e., MI and relaxation, in alternating order. Each of the tasks (MI vs. relaxation) was studied with and without feedback. The respective event-driven oscillatory activity, i.e., sensorimotor desynchronization (during MI) or synchronization (during relaxation), was rewarded with contingent feedback. Importantly, feedback onset was delayed to study the task-related cortical activity in the absence of feedback provision during the delay period. The reward modality was alternated every 15 trials between proprioceptive and visual feedback. Proprioceptive input was superior to visual input to increase the range of task-related spectral perturbations in the α- and β-band, and was necessary to consistently achieve MI-related sensorimotor desynchronization (ERD) significantly below baseline. These effects occurred in task periods without feedback as well. The increased accuracy and duration of learned brain self-regulation achieved in the proprioceptive condition was specific to the β-band. MI-related operant learning of brain self-regulation is facilitated by proprioceptive feedback and mediated in the sensorimotor β-band

Synaptobrevin cleavage by the tetanus toxin light chain is linked to the inhibition of exocytosis in chromaffin cells

Exocytosis of secretory granules by adrenal chromaffin cells is blocked by the tetanus toxin light chain in a zinc specific manner. Here we show that cellular synaptobrevin is almost completely degraded by the tetanus toxin light chain within 15 min. We used highly purified adrenal secretory granules to show that synaptobrevin, which can be cleaved by the tetanus toxin light chain, is localized in the vesicular membrane. Proteolysis of synaptobrevin in cells and in secretory granules is reversibly inhibited by the zinc chelating agent dipicolinic acid. Moreover, cleavage of synaptobrevin present in secretory granules by the tetanus toxin light chain is blocked by the zinc peptidase inhibitor captopril and by synaptobrevin derived peptides. Our data indicate that the tetanus toxin light chain acts as a zinc dependent protease that cleaves synaptobrevin of secretory granules, an essential component of the exocytosis machinery in adrenal chromaffin cells

Characterization of IgG and IgE Binding to Parvalbumin Derived from Commercially Important Fish Species

Rationale: Parvalbumin is recognized as pan-allergen in fish and frog. However, previous studies demonstrated that the IgE- and IgG-binding patterns to parvalbumins vary depending on the fish species. We aimed to use 3 anti-parvalbumin IgG and human IgE to investigate the contributing factors for the binding differences. Methods: Indirect enzyme-linked immunosorbent assay (ELISA) and IgG immunoblotting were used to determine the reactivity of the polyclonal anti-cod parvalbumin antibody and the commercially available, monoclonal anti-frog and anti-carp parvalbumin antibodies against raw muscle extracts of 25 fish species. Additionally, sera from 46 individuals with clinical history of fish allergy were analyzed for IgE reactivity to parvalbumin using indirect ELISA. Inhibition ELISAwas performed to determine the effects of heating and calcium on IgG-binding to parvalbumin. Results: The 3 IgG antibodies demonstrated varying specificity for different fish species. Polyclonal anti-cod parvalbumin antibody showed reactivity to a wider range of species, whereas the monoclonal anti-frog parvalbumin antibody showed the least cross-reactivity. The binding of the 3 IgG antibodies to parvalbumin was unaffected by heating, but the absence of calcium abolished the binding. IgE reactivity to cod parvalbumin or cod extracts were observed in \u3e 50% of individuals’ sera, whereas \u3c 0.1% of the sera showed reactivity to tuna and swordfish extracts. Both IgG and IgE antibodies showed low reactivity to tuna and swordfish that are apparently deficient in parvalbumin. Conclusions: These results suggested that the antibodies’ specificity to parvalbumins in various fish species is associated with the parvalbumin expression, its structural conformation, and the primary structure of antigenic determinations on parvalbumin

Adaptive Dispersion Compensation for Remote Fiber Delivery of NIR Femtosecond Pulses

We report on remote delivery of 25 pJ broadband near-infrared femtosecond light pulses from a Ti:sapphire laser through 150 meters of single-mode optical fiber. Pulse distortion due to dispersion is overcome with pre-compensation using adaptive pulse shaping techniques, while nonlinearities are mitigated using an SF10 rod for the final stage of pulse compression. Near transform limited pulse duration of 130 fs is measured after the final compression.Comment: 3 pages, 4 figure

Identification and Analysis of the IgE Binding by Parvalbumin and Other Potential Allergens in Different Fish and Frog Species

Rationale: Serological cross-reactivity to different fish and frog species is common among fish-allergic individuals.We examined the intra- and inter-individual diversity in IgE responses of fish-allergic subjects to various fish and frog species and identified novel allergens besides parvalbumin. Methods: Sera from 38 subjects with a clinical history of fish allergy were analyzed for IgE-binding profiles to crude extracts of 26 raw fish and frog species, and purified cod and carp parvalbumin using IgE-immunoblotting. Sera of 7 subjects showing similar IgE-binding profiles in the IgEimmmunoblotting were pooled to identify potential allergens in pilchard, herring, cod, cusk, and rainbow trout using two-dimensional electrophoresis (2D) combined with IgE-immunoblotting and liquid chromatography-tandem mass spectrometry. Results: IgE-immunoblotting demonstrated great diversity among the fish-allergic individuals with respect to the IgE-binding to the parvalbumins and non-parvalbumin proteins in fish and frog species. Of the 38 individuals, 26 (68%) and 21 (55%) reacted to cod and carp parvalbumin, respectively. However, low IgE reactivity to parvalbumin from frog, mahi-mahi, and swordfish was observed. The pooled sera showed IgE-binding to parvalbumin and its corresponding isoforms separated by 2D in all 5 species. The IgE from pooled sera also recognized several novel fish allergens, including alpha actin, enolase, creatine kinase, glyceraldehyde 3-phosphate dehydrogenase, and fast myosin light chain proteins. Conclusions: The variation in IgE-binding depended on the individuals and fish species analyzed. The results suggested parvalbumin as the major cross-reactive allergens among fish species. Further characterization of the novel fish allergens is warranted at the molecular level using sera from additional fish-allergic subjects