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The Faraday rotation measures of a sample of extragalactic radio sources projected within a third of an Abell radius of a galaxy cluster were compared with those of sources located further from cluster centers. The result strongly indicates that the distribution of the residual rotation measure (RRM) in the former population is broadened, at a confidence level exceeding 99%. The broadening is detectable out to 1h 50 −1 Mpc. Our best estimate of the excess Faraday rotation measure varies from 100±36 rad m −2 in the central sixth of an Abell radius to 36±15 rad m −2 further out. The combination of these results with electron densities determined from X-ray data for some of the clusters suggests that magnetic field strengths in cluster gas are of order 1 microgauss

New observations of the radio emission from the Coma cluster of galaxies have revealed the most detailed image of an intergalactic halo yet seen in a cluster of galaxies. The centroid of the halo emission is significantly displaced from that of the X-ray emission. The Faraday rotation of polarized emission from background radio sources has been measured. There is a significant contribution to the rotation measure (RM) of sources seen through the cluster. The excess RM, when combined with the X-ray data, has allowed direct measurement of the magnetic-field strength, at about 2 microG, providing an independent check of the widely used assumption of equipartition between the energy in relativistic particles and that in the magnetic field. The observations also allow an estimate of the degree of tangling of the cluster magnetic field. The magnetic field reversals seem to occur on a scale size of 13-40 kpc. The extent of the halo emission and the degree of field tangling indicate that the radio halo source must be sustained by particle reacceleration in the intracluster medium. 50 refs.

THE Coma cluster is a rich cluster of galaxies nested in an even larger supercluster of galaxies. The plane of the supercluster seems to be defined by the Coma cluster itself and another galaxy cluster, Abell 1367, which lies ∼40 Mpc farther west1, 2. The largest structures known are the giant voids and superclusters which are as large as 70h−175 Mpc (refs 3–5). The Coma cluster of galaxies seems to be located on the rim of a giant void6 in the three-dimensional distribution of galaxies. Here we describe the detection of faint, supercluster-scale radio emission at 326 MHz that extends between the Coma cluster of galaxies (Abell 1656) and the Abell 1367 cluster and which is apparently not associated with any individual galaxy system in the complex. The radiation's synchrotron origin implies the existence of a large-scale intercluster magnetic field with an estimated strength of 0.3–0.6 μG, which is remarkably strong. The synchrotron-emitting relativistic electrons cannot be older than a few times 108 yr, but we speculate that the magnetic field is the fossil of a pre-galactic primaeval field, which was amplified in the course of the formation of intergalactic voids and superclusters.

The effect of a radial steady-state temperature gradient on elastic-plastic expansion of a hollow sphere or a spherical cavity in an infinite medium is investigated for homogeneous, isotropic, incompressible, temperature-dependent elastic-plastic strain hardening material. By employing appropriate temperature-dependent elastic and plastic strain hardening laws based on experimental data, the solutions for spherical inflation problems can be obtained in terms of elementary functions

Response equations are obtained for hollow spheres of elastic, perfectly plastic material under hydrostatic loading, unloading, reverse loading, and reloading. Some interesting features of unloading, reverse loading, and reloading responses are observed. For sufficiently thick-walled spheres, reverse yielding occurs during unloading. The critical initial porosity is obtained for reverse yielding during unloading. Precompaction lowers the magnitude of the pressure maximum and delays the occurrence of the instability point.

Radio sources in the field of the extended SNR OA184 (G166.2+2.5) have been studied to determine the excess rotation measure (RM) arising from the SNR. Of a total of 32 radio sources observed with the VLA in the C configuration, eight are found to be polarized above 7σ The sources seen through the SNR show significantly high RM in comparison to background sources. The excess RM due to the Faraday active plasma in the SNR is estimated to be 150±20 rad m−2, which corresponds to . The sign of RMs of the sources within an area of about 2°×2° centred on the SNR shows a systematic longitudinal polarity change on either side of l ≈ 166°.2. Although a larger sample is needed to justify this, we tentatively interpret this “flip” as due to the reversal of an irregular component of the galactic magnetic field on a scale of order 100 pc.

In order to clarify the role of cavitation nuclei upon inception, the behavior of inception was carefully investigated in an extremely limited water flow through very small orifices less than 1.0 mm in diameter under a prescribed nuclei condition. The following facts of technical interest were determined: a) The desinent cavitation number (σd) decreased rapidly and exponentially with the orifice diameter d, up to one hundredth in magnitude; and b) the cavitation appearance in such limited flows was quite different from that in fully turbulent flows through larger orifices.

We evaluated the risks of thromboembolism, valve thrombosis, anticoagulant hemorrhage, and sudden cardiac death in two groups of patients. The groups were similar in age, sex, and associated cardiovascular diseases except for the method of prevention of thromboembolism and length of follow-up. The group receiving warfarin consisted of 74 patients with 85 valves. Patients were maintained on long-term warfarin therapy. Eight of the 74 patients in the warfarin group did not survive the operative period, for a mortality of 10.8%. Prevention of thromboembolism was managed solely with warfarin to maintain the prothrombin time of 1.5 times control. The group receiving ticlopidine and aspirin consisted of 88 patients with 93 heart valves. Patients received ticlopidine (500 mg) and aspirin (500 mg) daily for 3 months postoperatively and in half doses thereafter. Three of the 88 patients did not survive the operative period, for an operative mortality of 3.4%. Warfarin was added postoperatively for 3 months for 39 of the 88 ticlopidine and aspirin group patients with high risk factors. Patients were follow ed-up from 36 to 120 months, with a mean of 33.5 months, in the warfarin group; and 1 to 36 months, with a mean of 8.5 months in the ticlopidine and aspirin group. At the most recent follow-up, 90% of the patients were in New York Heart Association (NYHA) Classes I and II. There were 5 late deaths in the warfarin group, 3 due to thromboembolism and 2 due to anticoagulant-related cerebral hemorrhage. Nonfatal attacks of thromboembolism and anticoagulant-related hemorrhage were noted in 10 other cases during follow-up. There were no late deaths in the ticlopidine and aspirin group during the short period of follow-up, except i case 35 days after mitral valve replacement, already included in the operative deaths. There was no case of primary valve failure or anticoagulant-related hemorrhage, except minor epistaxis and hypermenorrhea in the ticlopidine and aspirin group during this follow-up. It is our strong impression that combining ticlopidine and aspirin in low-risk adults has a synergistic effect and had superior results in preventing thromboembolism without anticoagulant-related hemorrhage. Warfarin is also necessary in high-risk adults for preventing early thrombus formation along the valve suture line. We recommend antiplatelet aggregator therapy with ticlopidine and aspirin in low-risk adult patients with ST. JUDE MEDICAL® valves and additional warfarin for 3 months in the high-risk adults with ST. JUDE MEDICAL valves.

We present in this paper the first high-resolution spectral index map of the halo source Coma C, which was obtained combining WSRT data at 326 MHz and DRA0+VLA data at 1.4 GHz. The spectral index distribution shows a central region, of ∼8' radius, where the spectral index is almost constant (∼0.8), surrounded by a region where the spectrum steepens to α∼1.8. In addition, we present new observations of Coma C obtained with the WSRT at 608.5 MHz. The spectral index information and high-resolution maps are used to derive the physical conditions in Coma C and understand the processes which lead to the formation of halo sources in clusters

We report a search for $B$ decays to selected final states with the $\eta_c$ meson: $B^{\pm}\to K^{\pm}\eta_c\pi^+\pi^-$, $B^{\pm}\to K^{\pm}\eta_c\omega$, $B^{\pm}\to K^{\pm}\eta_c\eta$ and $B^{\pm}\to K^{\pm}\eta_c\pi^0$. The analysis is based on $772\times 10^6$ $B\bar{B}$ pairs collected at the $\Upsilon(4S)$ resonance with the Belle detector at the KEKB asymmetric-energy $e^+e^-$ collider. We set 90\% confidence level upper limits on the branching fractions of the studied $B$ decay modes, independent of intermediate resonances, in the range $(0.6-5.3)\times 10^{-4}$. We also search for molecular-state candidates in the $D^0\bar{D}^{*0}-\bar{D}^0D^{*0}$, $D^0\bar{D}^0+\bar{D}^0D^0$ and $D^{*0}\bar{D}^{*0}+\bar{D}^{*0}D^{*0}$ combinations, neutral partners of the $Z(3900)^{\pm}$ and $Z(4020)^{\pm}$, and a poorly understood state $X(3915)$ as possible intermediate states in the decay chain, and set 90\% confidence level upper limits on the product of branching fractions to the mentioned intermediate states and decay branching fractions of these states in the range $(0.6-6.9)\times 10^{-5}$.

The results of an attempt to probe the magnetoionic strength of the supernova remnant OA 184 (G166.2 + 2.5) by measuring the Faraday rotation measures of background radio sources in the field are described. The data reveal a systematic sign flip of the RMs within and/or around the SNR. The background RMs are consistent with an interstellar magnetic irregularity scale of the order of 100 pc. 16 references.