An inference monitor with real-time FFT spectral analysis for aradio observator

A system is described which uses a real-time fast Fourier transform (FFT) spectrum analyzer to monitor radio interference near 408 MHzs occurring at a radio observatory. Direction of arrival, frequency, intensity, and time of occurrence are recorded under the control of a microcomputer. A sensitive receiver can be connected to any one of eight directional antennas to establish direction of arrival. The receiver output is digitized to 8 b, and analyzed by the FFT spectrum analyzer which has a real-time bandwidth of 0.5 MHz. A total bandwidth of 20 MHz is analyzed in segments of 0.4 MHz. The analyzer uses the modified periodogram method developed by P.D. Welch (IEEE Trans. Audio Electroacoust., vol.AU-15, p.70-3, June 1967), and a Kaiser-Bessel windowing function is applied to ensure low sidelobes. Dynamic range is 40 dB, and the interference monitor obtains high sensitivity to very weak interfering signals by time averaging. Several general design principles which arise out of certain constraints are elucidated. Some new results are presented concerning the detectability of small signals by FFT processors     

Precipitation of Hydroxyapatite under Stearic Acid Monolayers

The nucleation and growth of hydroxyapatite (HAp) crystals from solutions with and without Langmuir monolayers of stearic acid (SA) were investigated. The monolayers apparently enhanced the nucleation of HAp. Monolithic, filmlike polycrystalline HAp with preferred orientation of (00l) planes parallel to the monolayer interface was precipitated, while colloidal and powdery precipitation in the bulk solution was predominant in the absence of the monolayer. Geometrical similarity was found between the hexagonal packing conformation of the SA headgroups in the monolayers and the alignment of calcium ions in the (001) plane of HAp. It was suggested that HAp crystals nucleated and grew epitaxially on the monolayer interface.     

Picosecond laser in situ keratomileusis with a 1053-nm Nd:YLF laser

BACKGROUND: Excimer laser in situ keratomileusis requires a microkeratome to generate an anterior corneal flap, plus an excimer laser to ablate the underlying stromal tissue. In this paper we introduce the concepts of laser flap formation and in situ keratomileusis using a picosecond laser. METHODS: A neodymium-doped yttrium-lithium-fluoride (Nd:YLF) laser with a plano-plano quartz applanation lens was used to generate various patterns of intrastromal photodisruption in human donor eyes to fashion anterior corneal flaps and generate intrastromal lenticules. RESULTS: Smooth intrastromal dissections, 6 mm in diameter, were generated 160 microns below the corneal surface when the laser delivered pulses at 1 kHz with energies of either 40 microJ/pulse or 60 microJ/pulse, placed 20 microns apart in an expanding spiral. This enabled us to fashion anterior corneal flaps. The ease of the surgery and quality of the dissection corresponded well, and it was evident that both deteriorated noticeably when the laser pulses were separated by 25 microns or 30 microns, regardless of pulse energy. Using 40 microJ laser pulses placed 20 microns apart we also created a 5-mm diameter, 320 microns thick (130 microns-450 microns deep) stromal lenticule below a corneal flap that was easily extracted when the flap was raised. CONCLUSIONS: Anterior corneal flaps were easily fashioned using a Nd:YLF laser. Picosecond laser in situ keratomileusis with a Nd:YLF laser could offer a favorable alternative to combined microkeratome/excimer laser in situ keratomileusis.     

Ultrasonography in the diagnosis of malignant lymphoma of the thyroid

To assess the degree of noise pollution in relation to the health and safety of the employees and commuters, a study on the levels of noise originating from various locomotives and also from different other sources was undertaken at Kalupur railway station of Gujarat State in India. The sound pressure levels (SPL) were measured on platforms. Noise dose count was monitored on a ticket collector on duty for 8 h. The results reflected that the SPLs in the platforms well exceeded the day time noise exposure limit. Further, the SPLs produced by loudspeakers were high and those by train whistles were intensely high pitched. The noise dose count of the ticket collector was also in excess of ACGIH standard. All these suggest that the SPLs in the platforms can endanger the healthful living of the users. Suitable control measures have been suggested.     

Nuclear relaxation in the superconducting state of (MDT-TTF)2AuI2

We report the results of our attempt to measure the proton nuclear relaxation rate, 1/T ₁, in the superconducting state of the title material. The relaxation rate in the superconducting state at a field of 1 T was found much longer than that in the normal state, but it became clear that the dominant contribution came from the normal core region. The nuclear relaxation at zero field was examined by using the field cycling technique. An ln(t) term in the relaxation curve was observed at low temperatures, suggesting the contribution of the creeping motion of vortices. We discuss the possibility to determine the intrinsic temperature dependence of 1/T ₁ in the superconducting state.     

Anesthesia for bilateral volume reduction surgery in a patient with severe bullous emphysema

An 80-year-old male with severe bullous emphysema underwent bilateral volume reduction surgery. He had suffered from dyspnea and was classified into Hugh-Jones III. In spirogram, forced vital capacity in 1 second was markedly low (0.38 l, corresponding to 19.4 % in % FEV1.0). Anesthesia was maintained by isoflurane combined with thoracic-epidural anesthesia to make extubation possible at the end of surgery. We used a critical care type ventilator (Servo 900C, Simens) for pressure controlled ventilation for fear that positive pressuse ventilation creates or aggravates airleaks. Surgery and anesthesia were performed uneventfully. We recommend lower concentration of a volatile agent combine with thoracic epidural analgesia and pressure controlled ventilation for the volume reduction surgery.     

Electrophysiologic effects of quinaprilat in dogs during acute myocardial ischemia and following reperfusion

BACKGROUND: There have been few studies concerning the electrophysiologic changes associated with the use of angiotensin-converting enzyme inhibitors in patients with acute myocardial infarction. We examined the electrophysiologic effects of quinaprilat in dogs during acute myocardial ischemia and following reperfusion. METHODS: The left anterior descending coronary artery was occluded for 10 min and reperfused for 10 min. Animals received intravenous quinaprilat (3 micrograms/kg per min, quinaprilat group) or saline (control group). We measured the ventricular effective refractory period and intra-myocardial conduction time within the left anterior descending coronary artery region (ischemic region) during myocardial ischemia and following reperfusion, and determined the frequency of ventricular fibrillation. RESULTS: The effective refractory period in the ischemic region decreased during myocardial ischemia and decreased further immediately after reperfusion in the control group. The intra-myocardial conduction time in the ischemic region increased during myocardial ischemia but rapidly shortened after reperfusion in the control group. In the quinaprilat group, however, no significant differences were evident between the ischemic and non-ischemic regions in either the effective refractory period or the intra-myocardial conduction time during myocardial ischemia or following reperfusion. The percentage shortening of the effective refractory period and the percentage prolongation of the intra-myocardial conduction time in the ischemic region were significantly lower in the quinaprilat group than in the control group during myocardial ischemia and following reperfusion. The frequency of ventricular fibrillation during myocardial ischemia and following reperfusion was significantly lower in the quinaprilat group (21%) than in the control group (74%; P < 0.01). CONCLUSIONS: Quinaprilat protects against electrophysiologic abnormalities, and may decrease arrhythmias during acute myocardial ischemia and following reperfusion.     

A case of osteopetrosis with an abnormal CK-MB/T-CK ratio

The comparative effects of sleep patterns and rates of cyclic alternating patterns (CAP rate) in a high quality innerspring mattress were compared to those on a unique foam support mattress in 10 normal subjects. Results showed no differences in sleep stages, number of wakes, or total sleep time between the two conditions. CAP rates were significantly reduced on the foam surface. CAP rate was sensitive to the first-night effect on both surfaces, but was blunted on the foam mattress.