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A model for dusty gas flows and dust fragmentation in cometary atmospheres is developed and applied to interpret the dust intensity profiles near the nucleus of Comet P/Halley. It is found that fragmentation is not the only physical mechanism for explaining the dust intensity profiles from the 1/z dependence in the region about 1 to 40 km from the nucleus. A combination of the geometric effect and dust fragmentation is a likely explanation for the profiles.

We developed a 1-D hydrodynamic model of dusty gas flow with dust fragmentation in a cometary atmosphere and performed calculations for a dust-size distribution with radiia =10−4— 10 cm and densities variable with dust size. A comparison was made with Giotto observations of dust jet intensities within 100 km of the nucleus of Comet Halley. We found that dust fragmentation cannot be solely responsible for the flattening of the dust intensity near the nucleus with respect to the 1/R law. We conclude that a combination of geometric effects and grain fragmentation may explain the observed intensity profiles.

Early analyses of the Ion Mass Spectrometer (IMS) data from the Giotto flyby of Comet P/Halley indicated significant abundances of CH(+) sub n (n = 1 to 4). The source of these ions was assumed to be frozen CH4 in the nucleus. An abundance of about 2 percent CH4 was consistent with this interpretation, resulting in a ratio of CH4/CO that is greater than the predicted limits for interstellar clouds or the solar nebula. However, subsequent analyses of data from the Giotto Neutral Mass Spectrometer indicate distributed sources of CO and H2CO in the coma that are most likely associated with organic (CHON) particles, rich in CH-bearing compounds that decay and produce CH(+) sub n species. A model is presented that qualitatively accounts for the measured spatial distribution of CO and H2CO, and indicates that most of the CH(+) sub n deduced from the Giotto IMS data may originate from organic compounds in the coma dust and not from volatiles released directly from the nucleus. As a consequence, the absence of CH4 in the icy phase of the nucleus is consistent with the observations with an upper limit of about 0.5 percent to the ratio CH4/CO. This is an important criterion for theories of comet formation.

A CAD system integrating switched-capacitor network function synthesis, circuit synthesis, and layout is presented. The tool addresses the design of programmable gain, cosine, interpolation, and arbitrary transfer functions in addition to canonical filter structures. Amplifier design is based on numerical optimization of highly accurate analytic models derived with the aid of symbolic-mathematics-based model development aids. The physical design of the filter is created by a general-purpose switched-capacitor circuit synthesizer. The tool makes it possible to synthesize a complete switched-capacitor signal path with full handcrafted quality in a single day. Examples taken from actual IC designs illustrate the utility and accuracy of the various functions. >

A 2.45-GHz wireless IC card system has been developed for a noncontact-type train station automatic gate system. This system consists of compact transmitter-receiver equipment and noncontact wireless IC cards. The newly developed technology used in this system comprises a small dual-port slot antenna for the card, a modulation-demodulation scheme for stable data transmission, and a cochannel carrier allocation system for operation with multiple gates. Operation of this wireless card system has been successfully demonstrated. >

The examination for Chlamydial infection was carried out in 49 children aged from 1 year 10 months to 15 years (mean age 9 years 6 months +/- 3 years 8 months) with laryngotracheal cicatricial stenosis (CS) provoked by long nasotracheal intubation. Antibodies to C. pneumoniae in diagnostically significant titers were detected in 13 of 49 children (26.5%), to C. trachomatis--in 1 patient who had both infections. All the infected patients except the latter carried tracheal canules or were decanulated. Age of the patients with Chlamydial infection at the time of examination and development of CS was significantly older than of non-infected children. No significant difference was found between these patients by duration of the intubation and of the disease. Consideration of the fact that 12 of 13 children with C. pneumoniae infection carried tracheocanules suggests that the infection may be secondary.

Emission features of C2 C3, CN, and dust in Comets Thiele (1985m), Hartley-Good (19851), and Giacobini-Zinner (1984e) have been analyzed and their mass loss rates of about 0.5, 1.1, and 0.8 Mg S-1 have been determined.

We apply our fluid dynamic model with chemical kinetics of dusty comet comae to P/Tempel 2. A brief summary of results concerning gas/dust dynamics and chemistry is given.

We apply our fluid dynamic model with chemical kinetics of dusty comet comae to P/Tempel 2. A brief summary of results concerning gas/dust dynamics and chemistry is given.

Emission features of C2, C3, CN, and dust in Comets Thiele (1985m), Hartley-Good (1985l), and Giacobini-Zinner (1984e) have been analyzed and their mass loss rates of about 0.5, 1.1, and 0.8 Mg s−1 have been determined.

Comets P/Brorsen-Metcalf and C/Okazaki-Levy-Rudenko appeared successively in 1989 and displayed various disturbances of their magnetospheres. We observed two cases of a phenomenon in which a disconnection event of the cometary plasma tail (on August 13 and November 16, 1989) was followed by a terrestrial magnetic storm (on August 14 and November 17). A survey of solar flares suggests that an identical solar flare excited successively the cometary magnetosphere and the Earth's magnetosphere in each case. The average velocities of the shock front in interplanetary space were estimated by using the magnetospheric disturbances of both the comets and the Earth together with the assumed responsible solar flare. It is speculated from the results that the propagation of the shock front associated with the flare is not symmetric with respect to the radial axis from the flare region of the Sun.

Spectrophotometric observations of comet Giacobini-Zinner were obtained on 11 September 1985. C 2 and NH 2 were found to be depleted in Giacobini-Zinner relative to an average comet by factors of 10 and 5, respectively. The ratio of the production rates, Q ( NH 2 )/ Q ( H 2 O ) = 2 × 10 −4 indicates a very low NH 3 /H 2 O abundance ratio if NH 2 comes mostly from photodissociation of NH 3 . The water production rate for Giacobini-Zinner at the time of the ICE encounter was found to be 2.4 × 10 28 molecules s −1 , in good agreement with spacecraft results. Neither neutral Na nor C 2 + ion was detected in the ground-based spectrum at the time of the ICE encounter. Therefore, Na + and C 2 + can be excluded from the candidates for the ions in the mass range 23 to 24 amu detected by the ICE ion composition instrument.

To investigate if O + ions originating from parent molecules of comet Halley can produce the ion fluxes observed at 28 × 10 6 km upstream of the comet on March 25, 1986, possible processes to produce high speed O atoms from a cometary nucleus are studied. It is found that O atoms dissociated from H 2 O and CO have average terminal speeds of ∼ 2.5 km s −1 and 3.4∼3.7km s −1 respectively. These O atoms cannot reach the ICE spacecraft at 28 × 10 6 km from Halley because of their low speeds. Oxygen atoms dissociated from CO 2 in a two-step process can have speeds up to 9.1 km s −1 so that a fraction of the O atoms may be able to reach ICE on March 25. These O atoms can produce O + ion flux of about 0.02 ion cm −2 s −1 , at 28×10 6 km upstream of the comet, in the energy range of 80 to 160 Kev with the solar wind speed of 500 to 700 km s −1 . The calculated O + ion flux is 4 orders of magnitude smaller than the observed fluxes of ∼ 100 ions cm −2 s −1 . Therefore it is very difficult to explain the observed energetic ion fluxes by ions of cometary origin.

A new anisotropic permanent magnet was developed in the Mn-Al-C system, using warm-plastic deformation, with the following magnetic properties : Br = 6100 G, bHc = 2700 Oe and (BH)max = 7.0 MG-Oe. This magnet has good machinability in that it can be shaped and drilled using a lathe while in the magnetic phase state. The particular characteristics of the Mn-Al-C system were investigated as to carbon concentration. It was found that, in order to obtain excellent magnetic properties, the carbon concentration must exceed its solubility limit in the magnetic phase (τ-phase).

An anisotropic polycrystalline magnet of a Mn‐Al‐C alloy with (BH) max=6 MG⋅Oe has been successfully produced by extrusion at about 700°C. During the study on this ternary alloy system, a ferromagnetic phase (τ‐phase) single crystal was obtained by annealing a high‐temperature phase (e‐phase) single crystal containing lamellae of the compound Mn3AlC, under the action of a uniaxial compressive stress. The formation process of the τ‐phase single crystal was analyzed. The process can be explained by the e (h.c.p.) →e′ (orthorhomb.) →τ (f.c.t.) transformations with the following orientation relationships: (0001)e ∥ (100)e′ ∥ (111)τ and ([1100]e ∥ [001]e′ ∥ [112]τ. The e′‐phase is new and has a B19‐type structure. The e→e′ transformation is a disorder‐order transformation and the e′→τ is martensitic. These single crystal results may be extended to the directionalization process for polycrystalline magnets.

To determine right (RV) and left ventricular (LV) volumes, a new technique was developed using ECG-gated single-photon emission computed tomography (SPECT). RV volumes of nine patients and LV volumes of 22 patients measured by SPECT and biplane contrast cineangiography were compared. In addition, volume and ejection fraction (EF) of the RV and LV were obtained by SPECT for 10 normal controls, 21 patients with old myocardial infarction (OMI), eight patients with hypertrophic cardiomyopathy (HCM) and 12 patients with dilated cardiomyopathy (DCM), and these results were compared. The intracardiac blood pool was labeled with Tc-99m sodium pertechnetate and 32 images were recorded through 180 degrees by a rotating gamma-camera. End-diastolic and end-systolic counts during 50 msec were recorded during 50 or 60 cardiac cycles. These counting data were reconstructed as tomographic images of vertical long-axial slices with thickness of a pixel without any attenuation correction. The numbers of voxels within the % cut-off level were summed, and the sum was multiplied by the one voxel volume. The cut-off level for ventricular delineation was determined as 45% by phantom studies. 1. The values obtained from SPECT and contrast angiography correlated well. 2. In normal controls, LV end-diastolic and end-systolic volumes were significantly less than those of the RV (p less than 0.05, p less than 0.001) and LVEF was significantly greater than the RVEF (p less than 0.001). 3. In OMI (single vessel disease), both end-diastolic and end-systolic volumes of the LV were significantly greater than those of normals (p less than 0.01, p less than 0.001) and LVEF was significantly less. In HCM end-systolic volumes of the RV were significantly less (p less than 0.05) than those of the normals. 4. LV volume was greater and LVEF was extremely low both in DCM and in OMI (multivessel disease) compared to that of the normals. In DCM, RV end-systolic volumes was greater and RVEF was lower than that of OMI (multi-vessel disease), indicating the deterioration of RV contractility , primarily in DCM. From these findings, it was concluded that this noninvasive technique may be useful for estimating left and right ventricular volumes.

A CAD (computer-aided design) system integrating filter function design, circuit design, and layout is discussed. The core numerical optimization sizer uses full-accuracy models, including nonideal effects. Both interactive and highly automatic, the system allows completion of demanding, nonstandard switched-capacitor filter designs in one day