Simple Mean-Field Theory for a Zero-Temperature Fermi Gas at a Feshbach Resonance

We present a simple two-channel mean field theory for a zero-temperature two-component Fermi gas in the neighborhood of a Feshbach resonance. Our results agree with recent experiments on the bare-molecule fraction as a function of magnetic field [Partridge et al., cond-mat/0505353]. Even in this strongly-coupled gas of Li-6, the experimental results depend on the structure of the molecules formed in the Feshbach resonance and, therefore, are not universal.Comment: 4 pages, 1 figure, 27+ references; submitted to PR

A High Quality Text-To-Speech System Composed of Multiple Neural Networks

While neural networks have been employed to handle several different text-to-speech tasks, ours is the first system to use neural networks throughout, for both linguistic and acoustic processing. We divide the text-to-speech task into three subtasks, a linguistic module mapping from text to a linguistic representation, an acoustic module mapping from the linguistic representation to speech, and a video module mapping from the linguistic representation to animated images. The linguistic module employs a letter-to-sound neural network and a postlexical neural network. The acoustic module employs a duration neural network and a phonetic neural network. The visual neural network is employed in parallel to the acoustic module to drive a talking head. The use of neural networks that can be retrained on the characteristics of different voices and languages affords our system a degree of adaptability and naturalness heretofore unavailable.Comment: Source link (9812006.tar.gz) contains: 1 PostScript file (4 pages) and 3 WAV audio files. If your system does not support Windows WAV files, try a tool like "sox" to translate the audio into a format of your choic

Magelonidae (annelida: Polychaeta) de las Seychelles 2: Descripción de cuatro especies más, tres de ellas nuevas para la ciencia

P align=justify>In 2000, the National Museum of Wales mounted a marine biological expedition to the Seychelles as part of the Shoals of Capricorn programme. Following this, three new species of Magelona (M. conversa, M. falcifera and M. gemmata) were described, and published in the Proceedings of the 7th International Polychaete Conference. In this second paper, the authors describe a further three new species (M. symmetrica, M. mahensis and M. cepiceps) and present a new record of M. pygmaea Nateewathana and Hylleberg, 1991 – previously known only from Thailand. The taxonomic affinities of the four species are discussed and a key is provided to all seven recorded from the Seychelles. En el año 2000, dentro del programa Shoals of Capricorn, el Museo Nacional del País de Gales organizó una expedición biológica marina a las Seychelles. Tras ella, se describieron tres nuevas especies de Magelona (M. conversa, M. falcifera, y M. gemmata) que fueron publicadas en los Proceedings of the 7th International Polychaete Conference. En este segundo trabajo, los autores describen tres nuevas especies más (M. symmetrica, M. mahensis y M. cepiceps) y citan nuevamente a M. pygmaea Nateewathana y Hylleberg, 1991 previamente sólo hallada en Tailandia. Se discuten las afinidades taxonómicas de las cuatro especies y se proporciona una clave para las siete especies citadas en las Seychelles. &nbsp

Collective molecule formation in a degenerate Fermi gas via a Feshbach resonance

We model collisionless collective conversion of a degenerate Fermi gas into bosonic molecules via a Feshbach resonance, treating the bosonic molecules as a classical field and seeding the pairing amplitudes with random phases. A dynamical instability of the Fermi sea against association into molecules initiates the conversion. The model qualitatively reproduces several experimental observations {[Regal et al., Nature {\bf 424}, 47 (2003)]}. We predict that the initial temperature of the Fermi gas sets the limit for the efficiency of atom-molecule conversion.Comment: 4 pages, 3 figures, 10+ references, accepted to PR

Lamellar Structures of MUC2-Rich Mucin: A Potential Role in Governing the Barrier and Lubricating Functions of Intestinal Mucus

Mucus is a ubiquitous feature of mammalian wet epithelial surfaces, where it lubricates and forms a selective barrier that excludes a range of particulates, including pathogens, while hosting a diverse commensal microflora. The major polymeric component of mucus is mucin, a large glycoprotein formed by several MUC gene products, with MUC2 expression dominating intestinal mucus. A satisfactory answer to the question of how these molecules build a dynamic structure capable of playing such a complex role has yet to be found, as recent reports of distinct layers of chemically identical mucin in the colon and anomalously rapid transport of nanoparticles through mucus have emphasized. Here we use atomic force microscopy (AFM) to image a MUC2-rich mucus fraction isolated from pig jejunum. In the freshly isolated mucin fraction, we find direct evidence for trigonally linked structures, and their assembly into lamellar networks with a distribution of pore sizes from 20 to 200 nm. The networks are two-dimensional, with little interaction between lamellae. The existence of persistent cross-links between individual mucin polypeptides is consistent with a non-self-interacting lamellar model for intestinal mucus structure, rather than a physically entangled polymer network. We only observe collapsed entangled structures in purified mucin that has been stored in nonphysiological conditions

The infrared and far-infrared spectra of sublimed films of formaldehyde

The infrared spectra of liquid and solid films of formaldehyde were taken over the range of 35 to 4,000 cm⁻¹ using Beckman IR 7 and IR 11 spectrometers. A new overtone band and a new combination band were found as well as three fundamental peaks due to lattice vibrations and several peaks arising from combinations of internal and external modes of vibration. The peak at 180-195 cm⁻¹ is very strong and appears to be due to libration of the formaldehyde molecule about the principal axes perpendicular to the axis of the carbon-oxygen bond. The considerably weaker peaks appearing at 60 and 100 cm⁻¹ probably are due to rotation about the axis of the carbon-oxygen bond and to translation. The spectrum obtained in the near infrared region is essentially the same as the spectrum reported by Harvey and Ogilvie. The frequency shifts of the peaks for different states of condensation indicate that hydrogen bonding does not occur in the liquid or solid and that the intermolecular binding forces are due largely to dipole-dipole interactions