Modulator for tone and binary signals

Tones and binary information are transmitted as phase variations on a carrier wave of constant amplitude and frequency. The carrier and tones are applied to a balanced modulator for deriving an output signal including a pair of sidebands relative to the carrier. The carrier is phase modulated by a digital signal so that it is + or - 90 deg out of phase with the predetermined phase of the carrier. The carrier is combined in an algebraic summing device with the phase modulated signal and the balanced modulator output signal. The output of the algebraic summing device is hard limited to derive a constant amplitude and frequency signal having very narrow bandwidth requirements. At a receiver, the tones and binary data are detected with a phase locked loop having a voltage controlled oscillator driving a pair of orthogonal detection channels

The Interstate Ozone Pollution Negotiations: OTAG, EPA, and a Novel Approach to Negotiated Rulemaking

Published in cooperation with the American Bar Association Section of Dispute Resolutio

U.S. Radio in the 21st Century: Staying the Course in Unknown Territory

This essay examines the development of the radio industry in the United States as it makes its way into the 21st century. Issues of regulation, technology, commerce, and culture are addressed

Pituitary Adenoma Hidden by Comorbid Cataract

Background: A pituitary adenoma is an abnormal growth in the pituitary gland. Pituitary adenomas are the most common cause of sellar masses accounting for approximately 10% of all intracranial neoplasms. Early visual symptom of pituitary adenoma can be hidden by comorbid cataract in elderly patients. Case Report: A 74 y.o. male presented to the eye clinic with blurry vision at all distances and has trouble with glare from lights. His best corrected visual acuity (BCVA) was 20/20-1 OD, 20/25-2 OS, but subjectively of poor quality. Slit lamp exam confirmed mild nuclear sclerotic cataract OU and normal fundus exam. Patient underwent uncomplicated cataract extraction with intraocular implant, OS first then OD. Post-op course was unremarkable until one month later when patient stated that his vision OS was blurry to the left. BCVA was 20/25 OD, 20/25-2 OS. Post-op exam was still normal including FCF. Humphrey visual field (HVF) however showed a bitemporal hemianopia. Patient was referred for a brain imaging. Brain MRI confirmed a 24 x 22 x 28 mm T2 isointense enhancing mass of the sella with suprasellar extension consistent with a pituitary macroadenoma. Patient underwent endonasal transphenoidal craniectomy for debulking of the tumor subsequently by an ENT specialist. Conclusion: Clinicians need to be sure the cataract matches the visual complaint. When in doubt further ancillary testing such as comprehensive HVF is crucial to detect visual pathway disorder and brain tumors. Co-management with corresponding specialist is essential to preserve vision and save life

Strictly One-Dimensional Electron System in Au Chains on Ge(001) Revealed By Photoelectron K-Space Mapping

Atomic nanowires formed by Au on Ge(001) are scrutinized for the band topology of the conduction electron system by k-resolved photoemission. Two metallic electron pockets are observed. Their Fermi surface sheets form straight lines without undulations perpendicular to the chains within experimental uncertainty. The electrons hence emerge as strictly confined to one dimension. Moreover, the system is stable against a Peierls distortion down to 10 K, lending itself for studies of the spectral function. Indications for unusually low spectral weight at the chemical potential are discussed.Comment: 4 pages, 4 figures - revised version with added Fig. 2e) and additional reference

Anderson Transition in Disordered Graphene

We use the regularized kernel polynomial method (RKPM) to numerically study the effect disorder on a single layer of graphene. This accurate numerical method enables us to study very large lattices with millions of sites, and hence is almost free of finite size errors. Within this approach, both weak and strong disorder regimes are handled on the same footing. We study the tight-binding model with on-site disorder, on the honeycomb lattice. We find that in the weak disorder regime, the Dirac fermions remain extended and their velocities decrease as the disorder strength is increased. However, if the disorder is strong enough, there will be a {\em mobility edge} separating {\em localized states around the Fermi point}, from the remaining extended states. This is in contrast to the scaling theory of localization which predicts that all states are localized in two-dimensions (2D).Comment: 4 page

Band structure and many body effects in graphene

We have determined the electronic bandstructure of clean and potassium-doped single layer graphene, and fitted the graphene π bands to a one- and three-near-neighbor tight binding model. We characterized the quasiparticle dynamics using angle resolved photoemission spectroscopy. The dynamics reflect the interaction between holes and collective excitations, namely plasmons, phonons, and electron-hole pairs. Taking the topology of the bands around the Dirac energy for n-doped graphene into account, we compute the contribution to the scattering lifetimes due to electron-plasmon and electron phonon coupling

A Vision- and Life-threatening Case of Peripheral Ulcerative Keratitis

Background: Peripheral ulcerative keratitis (PUK) is a rare but severe ocular manifestation most commonly associated with rheumatoid arthritis amongst other autoimmune diseases. Quick diagnosis and co-management with corneal specialist and rheumatologist are crucial to preserve vision and life. A rare case of PUK associated with rheumatoid arthritis (RA) is presented with updates on current understanding and co-management of this condition. Case Report: A 76 year-old Caucasian male presented to the eye clinic on a Friday as a new patient, with a chief complaint of a red right eye started two weeks ago and was treated with erythromycin ointment, but it got worse with moderate pain so he was referred over from the urgent care clinic. His BCVA OD, OS was 20/80 PHNI and PH20/25, respectively. Anterior segment evaluation showed severe conjunctival chemosis and injection, a superior temporal circular infiltrate and an inferior temporal linear infiltrate across the cornea with moderate corneal edema. Chart review confirmed the patient has been treated for rheumatoid arthritis with hydroxychloroquine and leflunomide for several years. The patient was diagnosed with PUK with mild scleritis associated with (RA) and initially treated with tobradex topical drops OD qid. His rheumatologist was contacted for co-management, and the patient was to return to clinic after the weekend. On the follow up visit, the patient felt better but the linear infiltrate persisted so oral prednisone 60mg/day was started with ofloxacin qid instead of Tobradex qid. The condition continued to improve over the next few follow up however the linear thinning of the cornea was not fully resolved so the patient was referred to a local corneal specialist. His rheumatologist continued to manage his RA closely and the patient confirmed that he was doing better overall at the latest visit. Conclusion: In cases of PUK with stromal thinning and scleritis, autoimmune diseases such as RA and systemic lupus erythema often are the underlying systemic cause. Prompt diagnosis and co-management with other specialists are essential to minimize irreversible vision loss and save lives