318 research outputs found
Highly efficient broadband polarization retarders and tunable polarization filters made of composite stacks of ordinary wave plates
By using the formal analogy between the evolution of the state vector in
quantum mechanics and the Jones vector in polarization optics, we construct and
demonstrate experimentally efficient broadband half-wave polarization retarders
and tunable narrowband polarization filters. Both the broadband retarders and
the filters are constructed by the same set of stacked standard multi-order
optical wave plates rotated at different angles with respect to their fast
polarization axes: for a certain set of angles this device behaves as a
broadband polarization retarder while for another set of angles it turns into a
narrowband polarization filter. We demonstrate that the transmission profile of
our filter can be centered around any desired wavelength in a certain vicinity
of the design wavelength of the wave plates solely by selecting appropriate
rotation angles
Scared or scarred: could ‘dissociogenic’ lesions predispose to nonepileptic seizures after head trauma?
Proposal for best practice in the use of video-EEG when psychogenic non-epileptic seizures are a possible diagnosis
The gold-standard for the diagnosis of psychogenic non-epileptic seizures (PNES) is capturing an attack with typical semiology and lack of epileptic ictal discharges on video-EEG. Despite the importance of this diagnostic test, lack of standardisation has resulted in a wide variety of protocols and reporting practices. The goal of this review is to provide an overview of research findings on the diagnostic video-EEG procedure, in both the adult and paediatric literature. We discuss how uncertainties about the ethical use of suggestion can be resolved, and consider what constitutes best clinical practice. We stress the importance of ictal observation and assessment and consider how diagnostically useful information is best obtained. We also discuss the optimal format of video-EEG reports; and of highlighting features with high sensitivity and specificity to reduce the risk of miscommunication. We suggest that over-interpretation of the interictal EEG, and the failure to recognise differences between typical epileptic and nonepileptic seizure manifestations are the greatest pitfalls in neurophysiological assessment of patients with PNES. Meanwhile, under-recognition of semiological pointers towards frontal lobe seizures and of the absence of epileptiform ictal EEG patterns during some epileptic seizure types (especially some seizures not associated with loss of awareness), may lead to erroneous PNES diagnoses. We propose that a standardised approach to the video-EEG examination and the subsequent written report will facilitate a clear communication of its import, improving diagnostic certainty and thereby promoting appropriate patient management
Cardiac Imaging Within Emergency CT Angiography for Acute Stroke Can Detect Atrial Clots
Cardiac embolism is presumed to cause a significant portion of cryptogenic strokes. Transesophageal echocardiography may detect intracardiac thrombi, but this remains a rare finding, possibly because remnant clots dissolve spontaneously or following thrombolysis. Cardiac imaging within cerebral CT angiography might offer an alternative method for thrombus detection within hyperacute stroke assessment. In a proof-of-concept study we analyzed records of patients aged ≥ 60 years that presented with suspected stroke and underwent extended cerebral CT angiography as part of their emergency assessment. CT imaging of patients with ischemic stroke or transient ischemic attack (TIA) and atrial fibrillation and of those with embolic strokes of undetermined source (ESUS) was reviewed for intracardiac clots and other cardiac or aortic pathology. Over a period of 3 months 59 patients underwent extended CT angiography for suspected stroke, 44 of whom received a final diagnosis of ischemic stroke or TIA. Of those, 17 had atrial fibrillation, and four fulfilled ESUS criteria. Thrombi were detected within atrial structures on CT angiography in three cases. In two ESUS patients complex atheromatosis of the proximal ascending aorta with irregular and ulcerating plaques was detected. Cardiac imaging within emergency cerebral CT angiography is feasible and can provide valuable diagnostic information in a patient group that might not routinely undergo transesophageal echocardiography. A small change to emergency assessment could potentially uncover cardioembolic pathology in cases that would have remained cryptogenic otherwise
A Review and Expert Opinion on the Neuropsychiatric Assessment of Motor Functional Neurological Disorders
Functional neurological (conversion) disorder (FND) is a prevalent and disabling condition at the intersection of neurology and psychiatry. Advances have been made in elucidating an emerging pathophysiology for motor FND, as well as in identifying evidenced-based physiotherapy and psychotherapy treatments. Despite these gains, important elements of the initial neuropsychiatric assessment of functional movement disorders (FND-movt) and functional limb weakness/paresis (FND-par) have yet to be established. This is an important gap from both diagnostic and treatment planning perspectives. In this article, the authors performed a narrative review to characterize clinically relevant variables across FND-movt and FND-par cohorts, including time course and symptom evolution, precipitating factors, medical and family histories, psychiatric comorbidities, psychosocial factors, physical examination signs, and adjunctive diagnostic tests. Thereafter, the authors propose a preliminary set of clinical content that should be assessed during early-phase patient encounters, in addition to identifying physical signs informing diagnosis and potential use of adjunctive tests for challenging cases. Although clinical history should not be used to make a FND diagnosis, characteristics such as acute onset, precipitating events (e.g., injury and surgery), and a waxing and waning course (including spontaneous remissions) are commonly reported. Active psychiatric symptoms (e.g., depression and anxiety) and ongoing psychosocial stressors also warrant evaluation. Positive physical examination signs (e.g., Hoover's sign and tremor entrainment) are key findings, as one of the DSM-5 diagnostic criteria. The neuropsychiatric assessment proposed emphasizes diagnosing FND by using "rule-in" physical signs while also considering psychiatric and psychosocial factors to aid in the development of a patient-centered treatment plan
Large area etching for porous semiconductors
Access full text - https://doi.org/10.1002/pssc.2004611595While electrochemical etching of small samples in the 1 cm region is relatively easy, this is not true for large areas, i.e. standard wafer sizes up to 300 mm. The paper outlines the specific demands and difficulties in some detail, discusses large area etching strategies and systems, in particular for very deep macropores, and presents and discusses various results from the large area etching system of the authors
Assessment of Potential Risk Factors for the Development of Persistent Postural-Perceptual Dizziness: A Case-Control Pilot Study
Objectives: (1) To assess whether neuroticism, state anxiety, and body vigilance are higher in patients with persistent postural-perceptual dizziness (PPPD) compared to a recovered vestibular patient group and a non-dizzy patient group; (2) To gather pilot data on illness perceptions of patients with PPPD.Materials and Methods: 15 cases with PPPD and two control groups: (1) recovered vestibular patients (n = 12) and (2) non-dizzy patients (no previous vestibular insult, n = 12). Main outcome measures: Scores from the Big Five Inventory (BFI) of personality traits, Generalized Anxiety Disorder - 7 (GAD-7) scale, Body Vigilance Scale (BVS), Dizziness Handicap Inventory (DHI), modified Vertigo Symptom Scale (VSS) and Brief Illness Perception Questionnaire (BIPQ).Results: Compared to non-dizzy patients, PPPD cases had higher neuroticism (p = 0.02), higher introversion (p = 0.008), lower conscientiousness (p = 0.03) and higher anxiety (p = 0.02). There were no differences between PPPD cases and recovered vestibular patients in BFI and GAD-7. PPPD cases had higher body vigilance to dizziness than both control groups and their illness perceptions indicated higher levels of threat than recovered vestibular patients.Conclusion: PPPD patients showed statistically significant differences to non-dizzy patients, but not recovered vestibular controls in areas such as neuroticism and anxiety. Body vigilance was increased in PPPD patients when compared with both recovered vestibular and non-dizzy patient groups. PPPD patients also exhibited elements of negative illness perception suggesting that this may be the key element driving the development of PPPD. Large scale studies focusing on this area in the early stages following vestibular insult are needed
Functional/dissociative seizures: Proposal for a new diagnostic label and definition by the ILAE task force
The acceptability and validity of the term "psychogenic nonepileptic seizures" (PNES) have been questioned. Currently, numerous alternative terms, such as “conversion,” “dissociative,” “functional,” “attacks,” and “events,” are used in both medical literature and clinical practice, leading to confusion among professionals and patients. The lack of a uniform diagnostic label is likely to impede research funding and service development. The International League Against Epilepsy (ILAE) Psychiatry Commission charged its task force focusing on these seizures to propose a more uniform and integrative terminology. Members of the previous ILAE PNES Task Force (2017–2021) helped to organize two workshops to try to build a consensus for a new terminology. These meetings involved experts by experience, clinicians, and researchers, including representatives of the Functional Neurological Disorders Society (an international professional organization), FND Hope (an international patient advocacy organization), and the American Epilepsy Society. The current task force (2021–2025) continued this work by reviewing the existing literature and debating the nomenclature and classification of seizures commonly labeled as PNES. The present proposal paper synthesizes the findings of this process. Based on our critical consideration of the literature, academic insights, and clinical experience, and noting the current international medical and psychiatric classification systems, the ILAE task force proposes the new term “functional/dissociative seizures” (FDS). This proposal paper explores the pros and cons of each component of the label “functional,” “dissociative,” and “seizure” from different perspectives, taking account of patient and health care professional acceptability, diagnostic and semiological considerations, underlying illness mechanisms, treatment provision, and health–economic, sociocultural, and linguistic factors. The dual characterization and use of a slash offer clinicians flexibility to adopt either “functional” or “dissociative,” or both, in their practice depending on the patient's profile, their own preferences, and the cultural/linguistic context. The abbreviation “FDS” is recommend for use in scientific writings
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