2,516 research outputs found

    A portable L-band voice transceiver for satellite communication

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    A portable L-band voice transceiver was developed as a feasibility model and can provide a half-duplex voice link to another terminal via the L-band transponder on the Applications Technology Satellite, ATS-6. The narrow band FM transceiver utilizes commercial subsystems including a UHF transceiver, provides an RF output power of 20 watts, weights less than 25 lbs., is housed in a plastic briefcase, can be powered by an automobile electrical system, and has been successfully operated with ATS-6 on numerous occasions. Design considerations and operation of the transceiver are described, along with alignment and testing procedures, packaging and cost considerations, subsystem performance requirements and overall transceiver performance characteristics

    Traveling-wave tube circuit simplifies microwave relay

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    Circuit with a sawtooth-modulated traveling-wave tube, which acts as a frequency converter and as an amplifier, simplifies microwave transmission. Lower power losses and reduced size and weight are also realized in this circuit

    Anosmia and Ageusia as the Only Indicators of Coronavirus Disease 2019 (COVID-19)

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    The patient is a 60-year-old woman with a history of vertigo and seasonal allergies who presented to the hospital with the chief complaint of headache. Radiological findings were negative for intracranial abnormalities. The headache was due to trigeminal neuralgia. She had concurrent complaints of anosmia and ageusia without fever, respiratory symptoms, or obvious risk factors. However, it was determined to test the patient for coronavirus disease 2019 (COVID-19) infection despite extremely low clinical suspicion. Unfortunately, she was found to be COVID-19 positive after she was discharged from the hospital while she remained asymptomatic. There is currently a lack of published case reports describing COVID-19 patients with the sole symptoms of anosmia and ageusia in the United States of America

    Iron Deficiency Anemia: An Unexpected Cause of an Acute Occipital Lobe Stroke in an Otherwise Healthy Young Woman

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    A 29-year-old caucasian woman who presented to the hospital with an acute onset of right eye visual disturbance and headache was found to have an acute left occipital lobe infarction. Past medical history was significant for iron deficiency anemia (IDA) secondary to menorrhagia. Her initial hemoglobin level was 7.8 G/DL, and her symptoms improved after iron and blood transfusions. Hypercoagulable studies were completed in the outpatient setting, and the results were unremarkable. Her acute stroke was most likely related to IDA as she had low cardiovascular risk factors along with a negative complete stroke workup

    Energy loss distributions of 7 TeV protons channeled in a bent silicon crystals

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    The energy loss distributions of relativistic protons axially channeled through the bent <100> Si crystals, with the constant curvature radius, R = 50 m, are studied here. The proton energy is 7 TeV and the thickness of the crystal is varied from 1 mm to 5 mm, which corresponds to the reduced crystal thickness, L, from 2.1 to 10.6, respectively. The proton energy was chosen in accordance with the large hadron collider project, at the European Organization for Nuclear Research, in Geneva, Switzerland. The energy loss distributions of the channeled protons were generated by the computer simulation method using the numerical solution of the proton equations of motion in the transverse plane. Dispersion of the proton scattering angle caused by its collisions with the crystal’s electrons was taken into account. [Projekat Ministarstva nauke Republike Srbije, br. III 45006

    TISSUE LOCALIZATION OF MULTIPLE FORMS OF ENZYMES * , †

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75551/1/j.1749-6632.1963.tb53749.x.pd

    The role of North Brazil Current transport in the paleoclimate of the Brazilian Nordeste margin and paleoceanography of the western tropical Atlantic during the late Quaternary

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    Author Posting. © The Author(s), 2014. This is the author's version of the work. It is posted here by permission of Elsevier for personal use, not for redistribution. The definitive version was published in Palaeogeography, Palaeoclimatology, Palaeoecology 415 (2014): 3-13, doi:10.1016/j.palaeo.2014.05.030.Reconstructions of surface paleoceanographic conditions of the western equatorial Atlantic and past climates of the adjacent Northeast Brazilian (the "Nordeste") continental margin were undertaken by analyzing sediments from a piston core and associated gravity and box cores recovered from 3107 meter water depth at 0° 20’ N on the equatorial Brazilian continental slope. The record is dated by radiocarbon analysis and oxygen isotopic stratigraphy of planktonic foraminifers and spans from near- modern to approximately 110 Ka. High-resolution XRF analysis provides insight into the paleoclimate history of the Nordeste during the last glacial interval. Several large-amplitude and abrupt peaks are observed in the time series of Ti/Ca and are usually accompanied by peaks of Fe/K. Together these record periods of increased precipitation and intense weathering on the adjacent continent and increased terrestrial sediment discharge from Nordeste rivers into the Atlantic. Within the limits of dating accuracy, most Ti/Ca peaks correlate with Heinrich events in the North Atlantic. This record thus corroborates, and extends back in time, the previous record of Arz et al (1998) determined on sediment cores from farther southeast along the Nordeste margin. Stable oxygen isotopic analysis and Mg/Ca paleothermometry on the near- surface-dwelling planktonic foraminiferal species Globierinoides ruber find that mean sea-surface temperature (SST) during glacial time (20 to 55 Ka, n = 97) was 23.89 ± 0.79 °C and the mean SST during the late Holocene (0 to 5 Ka, n = 14) was 26.89 ± 0.33 °C. SSTs were 0.5 to 2 °C higher and inferred sea-surface salinities were lower during most of the periods of elevated Ti/Ca, thus, as observed in previous studies, the western equatorial Atlantic was warm (at least locally) and the adjacent southern tropical continent was wet at the same time that the high-latitude North Atlantic was cold. Using the SYNTRACE-CCSM3 fully coupled climate model with transient forcing for the period 22 Ka to present, we find that decreased transport of the North Brazil Current co-occurs with reduced Atlantic meridional overturning circulation, and colder-than-normal SSTs in the North Atlantic region. These simulated conditions are invariably associated with significantly increased precipitation in the Nordeste region.Funding for the cruise and post-cruise science was provided to PAB by NSF-OCE-0823650
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