An electro-optical simulation methodology for the analysis of single-event radiation effects in photonic devices

Photonic integrated circuits (PICs) are devices that transmit and perform operations on optical signals. PICs offer significant benefits compared to conventional electronics, including increased data transmission rates. Despite the desire to leverage these benefits for space systems increasing in recent years, the study of radiation effects in PICs is still limited, especially the transient radiation effects known as single-event effects (SEEs). A roadblock in advancing the understanding of SEEs in PICs is the inability to co-simulate radiation effects in both the optical and electrical domains. Establishing a means of simulating SEEs in PICs would aide in: (1) modeling SEEs in various devices, (2) determining specific mechanisms by which SEEs upset devices, and (3) discovering methods for improving the radiation hardness of PICs. This work introduces a methodology for the simulation of SEEs in PICs that couples optical and electrical domain simulations that are required to fully characterize SEEs in PICs

The Piano Style of Claude Debussy

This thesis begins by describing the piano's history and development and then goes into how Claude Debussy used the piano in his music and the style in which he composed for the piano

Telehealth and Physical Therapy Clinical Decision Making in a Patient with a Falcine Meningioma

Telehealth utilizes information technologies and communication networks to deliver healthcare and education with lower costs and improved access, quality, and efficiency of healthcare services.  This report describes the application of telehealth for medical screening, clinical decision making, and medical referral in a physical therapy practice. The patient described was a 50-year old man who contacted his physical therapist via telephone for a chief complaint of worsening left sided numbness and tingling that began insidiously 2 days prior.  Further questioning revealed that the patient also complained of left ankle weakness, and slight unsteadiness with walking. He had not been feeling well and had been experiencing increasing bouts of unexplained fatigue over the previous two months that were now interfering with his work and recreational activities. The patient was evaluated by his physician the next day.  Magnetic resonance imaging of the brain revealed a large (4 cm) falcine meningioma in the right parietal region.  The patient was immediately referred to a neurosurgeon and underwent a craniotomy and tumor resection ten days later and subsequent gamma knife radiosurgery of the residual tumor bed two months after craniotomy and tumor resection.  Follow-up imaging one year later revealed no evidence of recurrence or residual tumor.  This patient case underscores the importance of recognizing signs and symptoms of serious disease, and how referral following telehealth via telephone can inform diagnosis

Diagnosis of Internal Carotid Artery Stenosis in a Patient Referred to a Physiotherapist for Dizziness

PURPOSE: The purpose of this report is to describe the diagnostic focus of the clinical decision-making process for a patient referred to a physiotherapist for treatment of persistent dizziness, who was subsequently diagnosed with severe stenosis of the internal carotid arteries. CASE DESCRIPTION: The patient was a 79-year-old man who was referred to a physiotherapist by his primary care physician for the treatment of persistent intermittent dizziness. The patient’s dizziness began 6 months prior insidiously; it was worsening over time and now interfered with activities of daily living. The patient denied cervical pain or headaches, numbness or tingling in his extremities, difficulty maintaining balance with walking, unsteadiness, muscle weakness, dysphagia, drop attacks, diplopia or dysarthria. At the physiotherapist’s initial evaluation, cervical range of motion was moderately restricted in all motions and his dizziness was elicited with changes in head position. The patient’s neurological examination was unremarkable. Due to positional complaints of dizziness, a Dix–Hallpike test was used to screen for benign paroxysmal positional vertigo, which was positive for symptoms reproduction; however, no nystagmus was noted. The patient also became diaphoretic and exhibited significant discoloration of his face during the test. OUTCOMES: Due to concern over vascular compromise, carotid duplex ultrasonography and magnetic resonance angiography were completed and revealed near complete occlusion of the left internal carotid artery at its origin. The patient subsequently underwent a left internal carotid endarterectomy with resolution of symptoms and a return to all activities of daily living. DISCUSSION: Carotid artery stenosis, although frequently asymptomatic until severe, may manifest as complaints of dizziness that mimic peripheral vestibular dysfunction. Appropriate and prudent screening and referral is necessary if clinical symptoms suggestive of vascular compromise are present

The Advanced Compton Telescope

The Advanced Compton Telescope (ACT), the next major step in gamma-ray astronomy, will probe the fires where chemical elements are formed by enabling high-resolution spectroscopy of nuclear emission from supernova explosions. During the past two years, our collaboration has been undertaking a NASA mission concept study for ACT. This study was designed to (1) transform the key scientific objectives into specific instrument requirements, (2) to identify the most promising technologies to meet those requirements, and (3) to design a viable mission concept for this instrument. We present the results of this study, including scientific goals and expected performance, mission design, and technology recommendations

NuSTAR Spectroscopy of Multi-Component X-ray Reflection from NGC 1068

We report on observations of NGC1068 with NuSTAR, which provide the best constraints to date on its $>10$~keV spectral shape. We find no strong variability over the past two decades, consistent with its Compton-thick AGN classification. The combined NuSTAR, Chandra, XMM-Newton, and Swift-BAT spectral dataset offers new insights into the complex reflected emission. The critical combination of the high signal-to-noise NuSTAR data and a spatial decomposition with Chandra allow us to break several model degeneracies and greatly aid physical interpretation. When modeled as a monolithic (i.e., a single N_H) reflector, none of the common Compton-reflection models are able to match the neutral fluorescence lines and broad spectral shape of the Compton reflection. A multi-component reflector with three distinct column densities (e.g., N_H~1.5e23, 5e24, and 1e25 cm^{-2}) provides a more reasonable fit to the spectral lines and Compton hump, with near-solar Fe abundances. In this model, the higher N_H components provide the bulk of the Compton hump flux while the lower N_H component produces much of the line emission, effectively decoupling two key features of Compton reflection. We note that ~30% of the neutral Fe Kalpha line flux arises from >2" (~140 pc), implying that a significant fraction of the <10 keV reflected component arises from regions well outside of a parsec-scale torus. These results likely have ramifications for the interpretation of poorer signal-to-noise observations and/or more distant objects [Abridged].Comment: Submitted to ApJ; 23 pages (ApJ format); 11 figures and 3 tables; Comments welcomed

Charge Isomers of Myelin Basic Protein: Structure and Interactions with Membranes, Nucleotide Analogues, and Calmodulin

As an essential structural protein required for tight compaction of the central nervous system myelin sheath, myelin basic protein (MBP) is one of the candidate autoantigens of the human inflammatory demyelinating disease multiple sclerosis, which is characterized by the active degradation of the myelin sheath. In this work, recombinant murine analogues of the natural C1 and C8 charge components (rmC1 and rmC8), two isoforms of the classic 18.5-kDa MBP, were used as model proteins to get insights into the structure and function of the charge isomers. Various biochemical and biophysical methods such as size exclusion chromatography, calorimetry, surface plasmon resonance, small angle X-ray and neutron scattering, Raman and fluorescence spectroscopy, and conventional as well as synchrotron radiation circular dichroism were used to investigate differences between these two isoforms, both from the structural point of view, and regarding interactions with ligands, including calmodulin (CaM), various detergents, nucleotide analogues, and lipids. Overall, our results provide further proof that rmC8 is deficient both in structure and especially in function, when compared to rmC1. While the CaM binding properties of the two forms are very similar, their interactions with membrane mimics are different. CaM can be used to remove MBP from immobilized lipid monolayers made of synthetic lipids - a phenomenon, which may be of relevance for MBP function and its regulation. Furthermore, using fluorescently labelled nucleotides, we observed binding of ATP and GTP, but not AMP, by MBP; the binding of nucleoside triphosphates was inhibited by the presence of CaM. Together, our results provide important further data on the interactions between MBP and its ligands, and on the differences in the structure and function between MBP charge isomers