134 research outputs found

    Waveguide for vortex mode generation in HVAC cloud management communication

    Get PDF
    Optical modes allow for the transmission of data by propagating light in a singular coherent form along the channel. By constructing a special waveguide structure, a unique mode may be formed in a plane perpendicular to the transmission axis. This paper elucidates on the design of a waveguide to generate unique vortex modes and analyses the properties of the generated modes

    Effect of Low versus High Frequency Subthalamic Deep Brain Stimulation on Speech Intelligibility and Verbal Fluency in Parkinson’s Disease: A Double-Blind Study

    Get PDF
    BACKGROUND: Subthalamic deep brain stimulation (STN-DBS) is an established treatment for late stage Parkinson's disease (PD). Speech intelligibility (SI) and verbal fluency (VF) have been shown to deteriorate following chronic STN-DBS. It has been suggested that speech might respond favourably to low frequency stimulation (LFS). OBJECTIVE: We examined how speech intelligibility, perceptual speech characteristics, phonemic and semantic VF and processes underlying it (clustering and switching) respond to LFS of 60 and 80 Hz in comparison to high frequency stimulation (HFS) (110, 130 and 200 Hz). METHODS: In this double-blind study, 15 STN-DBS PD patients (mean age 65, SD = 5.8, 14 right handed, three females), were assessed at five stimulation frequencies: 60 Hz, 80 Hz, 110 Hz, 130 Hz and 200 Hz. In addition to the clinical neurological assessment of speech, VF and SI were assessed. RESULTS: Speech intelligibility and in particular articulation, respiration, phonation and prosody improved with LFS (all p <  0.05). Phonemic VF switching improved with LFS (p = 0.005) but this did not translate to an improved phonemic VF score. A trend for improved semantic VF was found. A negative correlation was found between perceptual characteristics of speech and duration of chronic stimulation (all p <  0.05). CONCLUSIONS: These findings highlight the need for meticulous programming of frequency to maximise speech intelligibility in chronic STN-DBS. The findings further implicate stimulation frequency in changes to specific processes underlying VF, namely phonemic switching and demonstrate the potential to address such deficits through advanced adjustment of stimulation parameters

    Національно-демократичні об'єднання та політичні партії в Україні кінця XIX - початку XX століття

    Get PDF
    Deep brain stimulation (DBS) has become increasingly important for the treatment and relief of neurological disorders such as Parkinson's disease, tremor, dystonia and psychiatric illness. As DBS implantations and any other stereotactic and functional surgical procedure require accurate, precise and safe targeting of the brain structure, the technical aids for preoperative planning, intervention and postoperative follow-up have become increasingly important. The aim of this paper was to give and overview, from a biomedical engineering perspective, of a typical implantation procedure and current supporting techniques. Furthermore, emerging technical aids not yet clinically established are presented. This includes the state-of-the-art of neuroimaging and navigation, patient-specific simulation of DBS electric field, optical methods for intracerebral guidance, movement pattern analysis, intraoperative data visualisation and trends related to new stimulation devices. As DBS surgery already today is an important technology intensive domain, an "intuitive visualisation" interface for improving management of these data in relation to surgery is suggested

    Deep brain stimulation for refractory obsessive-compulsive disorder (OCD): emerging or established therapy?

    Get PDF
    A consensus has yet to emerge whether deep brain stimulation (DBS) for treatment-refractory obsessive-compulsive disorder (OCD) can be considered an established therapy. In 2014, the World Society for Stereotactic and Functional Neurosurgery (WSSFN) published consensus guidelines stating that a therapy becomes established when “at least two blinded randomized controlled clinical trials from two different groups of researchers are published, both reporting an acceptable risk-benefit ratio, at least comparable with other existing therapies. The clinical trials should be on the same brain area for the same psychiatric indication.” The authors have now compiled the available evidence to make a clear statement on whether DBS for OCD is established therapy. Two blinded randomized controlled trials have been published, one with level I evidence (Yale-Brown Obsessive Compulsive Scale (Y-BOCS) score improved 37% during stimulation on), the other with level II evidence (25% improvement). A clinical cohort study (N = 70) showed 40% Y-BOCS score improvement during DBS, and a prospective international multi-center study 42% improvement (N = 30). The WSSFN states that electrical stimulation for otherwise treatment refractory OCD using a multipolar electrode implanted in the ventral anterior capsule region (including bed nucleus of stria terminalis and nucleus accumbens) remains investigational. It represents an emerging, but not yet established therapy. A multidisciplinary team involving psychiatrists and neurosurgeons is a prerequisite for such therapy, and the future of surgical treatment of psychiatric patients remains in the realm of the psychiatrist
    corecore