9,420 research outputs found
Preconditioning of low-frequency repetitive transcranial magnetic stimulation with transcranial direct current stimulation: evidence for homeostatic plasticity in the human motor cortex
Recent experimental work in animals has emphasized the importance of homeostatic plasticity as a means of stabilizing the properties of neuronal circuits. Here, we report a phenomenon that indicates a homeostatic pattern of cortical plasticity in healthy human subjects. The experiments combined two techniques that can produce long-term effects on the excitability of corticospinal output neurons: transcranial direct current stimulation (TDCS) and repetitive transcranial magnetic stimulation (rTMS) of the left primary motor cortex. "Facilitatory preconditioning" with anodal TDCS caused a subsequent period of 1 Hz rTMS to reduce corticospinal excitability to below baseline levels for >20 min. Conversely, "inhibitory preconditioning" with cathodal TDCS resulted in 1 Hz rTMS increasing corticospinal excitability for at least 20 min. No changes in excitability occurred when 1 Hz rTMS was preceded by sham TDCS. Thus, changing the initial state of the motor cortex by a period of DC polarization reversed the conditioning effects of 1 Hz rTMS. These preconditioning effects of TDCS suggest the existence of a homeostatic mechanism in the human motor cortex that stabilizes corticospinal excitability within a physiologically useful range
Experimental study of the eta-meson interaction with two-nucleons
By means of the COSY-11 detection system, using a stochastically cooled
proton beam of the cooler synchrotron COSY and a hydrogen cluster target, we
have performed a high statistics measurement of the pp --> pp eta reaction at
an excess energy of Q = 15.5 MeV.
The experiment was based on the four-momentum determination of both outgoing
protons. This permits to identify pp --> pp eta events and to derive the
complete kinematical information of the eta-p-p-system allowing for subsequent
investigations of the eta-p interaction.
The observed spectrum of the invariant mass of the proton-proton system
deviates strongly from the phase-space distribution revealing the influence of
the final-state-interaction among the outgoing particles or nontrivial features
of the primary production mechanism.Comment: 6 pages, 4 figures, Talk presented at Meson 2002, 7th International
Workshop on Meson Production, Properties and Interaction, Cracow, Poland,
24-28 May 200
Analysing power A(y) in the reaction p(pol.)p --> pp eta near threshold
A first measurement of the analysing power in the reaction p(pol)p --> pp eta
near the production threshold has been performed at the internal facility
COSY-11 at the COoler SYnchrotron COSY.Comment: 4 pages, 2 figures, Presented at Meson 2002: 7th International
Workshop on Production, Properties and Interaction of Mesons, Cracow, Poland,
24-28 May 200
Embolization in an adrenocortical carcinoma as palliative therapy
Background: With an annual incidence of 0.2% of new cases per 100,000 inhabitants, adrenocortical carcinoma is rare. In advanced tumor only palliative treatment modalities are practicable. Because of scarcity of the tumor, standard treatment has not been defined. The decision on therapy frequently depends on the individual situation. Tumor embolization and chemotherapy are amongst the possible options. Patient and Methods: We report on a case of a 32-year-old female patient with a large-volume hormonally active adrenocortical carcinoma and hematogenous liver metastases. This carcinoma was confirmed histologically by means of liver biopsy. Owing to the large tumor extent and metastatic spreading and also in view of the poor general condition of the patient, curative surgical therapy was not possible. For this reason, a local approach was chosen primarily with transarterial tumor embolization at the capillary level. Systemic chemotherapy was given afterwards. Results: Improvement of the patient's general condition, especially the pronounced pain symptoms, could be achieved for a short time by the embolization: both, the patient's clinical condition and the laboratory test parameters improved. However, a rapid tumor progression occured under chemotherapy, which was started after embolization. Conclusion: In advanced adrenocortical carcinoma, tumor embolization can lead to a stabilization of the disease and improvement of the symptoms as appraised by palliative criteria in some patients
Total and Differential Cross Sections for the pp-->pp eta-prime Reaction Near Threshold
The eta-prime meson production in the reaction pp-->pp eta-prime has been
studied at excess energies of Q = 26.5, 32.5 and 46.6 MeV using the internal
beam facility COSY-11 at the cooler synchrotron COSY. The total cross sections
as well as one angular distribution for the highest Q-value are presented. The
excitation function of the near threshold data can be described by a pure
s-wave phase space distribution with the inclusion of the proton-proton final
state interaction and Coulomb effects. The obtained angular distribution of the
eta-prime mesons is also consistent with pure s-wave production.Comment: 6 pages, 5 figures, submitted to Eur. Phys. J.
Forward K+ production in subthreshold pA collisions at 1.0 GeV
K+ meson production in pA (A = C, Cu, Au) collisions has been studied using
the ANKE spectrometer at an internal target position of the COSY-Juelich
accelerator. The complete momentum spectrum of kaons emitted at forward angles,
theta < 12 degrees, has been measured for a beam energy of T(p)=1.0 GeV, far
below the free NN threshold of 1.58 GeV. The spectrum does not follow a thermal
distribution at low kaon momenta and the larger momenta reflect a high degree
of collectivity in the target nucleus.Comment: 4 pages, 3 figure
A Declarative Validator for GSOS Languages
Rule formats can quickly establish meta-theoretic properties of process
algebras. It is then desirable to identify domain-specific languages (DSLs)
that can easily express rule formats. In prior work, we have developed
Lang-n-Change, a DSL that includes convenient features for browsing language
definitions and retrieving information from them. In this paper, we use
Lang-n-Change to write a validator for the GSOS rule format, and we augment
Lang-n-Change with suitable macros on our way to do so. Our GSOS validator is
concise, and amounts to a few lines of code. We have used it to validate
several concurrency operators as adhering to the GSOS format. Moreover, our
code expresses the restrictions of the format declaratively.Comment: In Proceedings PLACES 2023, arXiv:2304.0543
Creation of ventricular septal defects on the beating heart in a new pig model
Background/ Aims: So far, surgical and interventional therapies for muscular ventricular septal defects ( mVSDs) beyond the moderator band have had their limitations. Thus, alternative therapeutic strategies should be developed. We present a new animal model for the evaluation of such strategies. Methods: In a pig model ( n = 9), anterolateral thoracotomy was performed for exposure of the left ventricle. mVSDs were created under two- and three- dimensional echocardiography with a 7.5- mm sharp punch instrument, which was forwarded via a left ventricular puncture without extracorporeal circulation. Results: Creation of mVSDs was successful in all animals ( n = 9) confirmed by echocardiography, hemodynamic measurements and autopsy. The defects were located in the midmuscular ( n = 4), apical ( n = 1), inlet ( n = 2) and anterior part ( n = 2) of the muscular septum. All animals were hemodynamically stable for further procedures. The diameter and shunt volume of the mVSDs were 4.8 - 7.3 mm ( mean: 5.9 mm) and 12.9 - 41.3% ( mean: 22.1%), respectively. Autopsy confirmed in all animals the creation of a substantial defect. Conclusion: The described new technique for creation of an mVSD on the beating heart in a pig model is suitable for the evaluation of new therapeutic strategies for mVSD closure. Copyright (C) 2008 S. Karger AG, Basel
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