We construct a high-resolution mass map of the cluster 0024ϩ1654, based on a parametric inversion z ϭ 0.39 of the associated gravitational lens. The lens creates eight well-resolved subimages of a background galaxy, seen in deep imaging with the Hubble Space Telescope. 1 Excluding mass concentrations centered on visible galaxies, more than 98% of the remaining mass is represented by a smooth concentration of dark matter centered near the brightest cluster galaxies, with a 35 kpc soft core. The asymmetry in the mass distribution is less than 3% Ϫ1 h inside 107 h Ϫ1 kpc radius. The dark matter distribution we observe in CL 0024 is far more smooth, symmetric, and nonsingular than in typical simulated clusters in either or cold dark matter cosmologies. Q ϭ 1 Q ϭ 0.3 Integrated to a 107 h Ϫ1 kpc radius, the rest-frame mass-to-light ratio is M/ .

We observe that field emitters made from carbon nanotubes exhibit excellent macroscopic emission properties; they can operate at a very large current density, as high as 4 A/cm 2 . At electric fields as low as 4-7 V/m, they emit technologically useful current densities of 10 mA/cm 2 . We show that the emission originates from nanotube ends with a characteristic structured ring pattern. The emission characteristics and durability of the carbon nanotube cold cathodes offer promising applications for vacuum microelectronic devices.

We explored a database covering seven dialects of British and Irish English and three different styles of speech to find acoustic correlates of prominence. We built classifiers, trained the classifiers on human prominence/nonprominence judgments, and then evaluated how well they behaved. The classifiers operate on 452 ms windows centered on syllables, using different acoustic measures. By comparing the performance of classifiers based on different measures, we can learn how prominence is expressed in speech. Contrary to textbooks and common assumption, fundamental frequency (f0) played a minor role in distinguishing prominent syllables from the rest of the utterance. Instead, speakers primarily marked prominence with patterns of loudness and duration. Two other acoustic measures that we examined also played a minor role, comparable to f0. All dialects and speaking styles studied here share a common definition of prominence. The result is robust to differences in labeling practice and the dialect of the labeler.

Strong and sustained electron emission at low electric fields was observed in undoped, nanostructured diamond. Electron emission of 10 milliamperes per square centimeter was observed at applied fields of 3 to 5 volts per micrometer. These are the lowest fields ever reported for any field-emitting material at technologically useful current densities. The emitter consists of a layer of nanometer-size diamond particulates, which is heat-treated in a hydrogen plasma. These emission characteristics are attributed to the particles' high defect density and the low electron affinity of the diamond surface. Such emitters are technologically useful, because they can be easily and economically fabricated on large substrates.

The vacuum tunneling probe can serve as a sensitive transducer of position into current. The performance of such a transducer is characterized by both the uncertainty in the inferred position Ax and the uncertainty in the momentum transfer hp during the measurement. For realistic barrier parameters we find that the uncertainty product b,x hp differs by less than 1% from A'/2. We also calculate the expectation values of the force associated with tunneling electrons. If sufficiently sensitive force measurements can be made, this force can provide information about a surface or an absorbed atom, differing from that provided by the tunneling current.

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We have confined over 5xl0 12 atoms of hydrogen in a static magnetic trap. The atoms are loaded into the trap by precooling with a dilution refrigerator. At operating densities near lx 10 13 cm -3 the gas is observed to be electron and nuclear polarized in the uppermost hyperfine state. The long lifetime of the trapped gas (over 20 min) suggests that it is thermally decoupled from the wall and has evaporatively cooled to a temperature of about 40 mK. The residual decay of the gas density is consistent with spin relaxation induced by dipolar interactions between atoms.

The mathematical models of intonation used in speech technology are often inaccessible to linguists. By the same token, phonological descriptions of intonation are rarely used by speech technologists, as they cannot be implemented directly in applications. Consequently, these research communities do not benefit much from each other's insights. In this paper, we explore the interface between the disciplines, in search of bridges between intonational phonology and speech technology. In a corpus of speech data from seven dialects of English, we hand-labeled over 700 sentences and identified seven nuclear accent types. Then we fitted a third-order polynomial to the fundamental frequency (F0) contour in the region around the accent mark. The polynomial captures the local shape (time-dependence) of F0 in a few numbers, in our case, four coefficients. The coefficients were subjected to statistical analysis. Nineteen of the 21 pairs of accent types differed significantly in one or more coefficients. Our approach bridges the gap between intonational phonology and speech technology. It provides quantitative, empirically testable models of intonation labels that can be implemented in applications.