Biomedical subjects

J Fineberg

Publications and source records attributed to J Fineberg.

At least 19 recordsLinked to original sources

PubMed2000

Turbulence and wave breaking effects on air-water gas exchange

We present an experimental characterization of the effects of turbulence and breaking gravity waves on air-water gas exchange in standing waves. We identify two regimes that govern aeration rates: turbulent transport when no wave breaking occurs and bubble dominated transport when wave breaking occurs. In both regimes, we correlate the qualitative changes in the aeration rate with corresponding changes in the wave dynamics. In the latter regime, the strongly enhanced aeration rate is correlated with measured acoustic emissions, indicating that bubble creation and dynamics dominate air-water exchange.

Journal Article↗

PubMed2000

Temporally harmonic oscillons in newtonian fluids

Stationary, highly localized (oscillon) structures are observed in a Newtonian fluid when nonlinear surface waves are parametrically excited with two frequencies. Oscillons have a characteristic structure, that of periodically self-focusing jets. In contrast to previously observed oscillons in highly non-Newtonian media, these states are temporally harmonic with the forcing. For wave amplitudes greater than a critical value, they nucleate from an initial pattern via a hysteretic bifurcation, and can therefore be localized on a background of patterns with a variety of different spatial symmetries.

Journal Article↗

PubMed2000

Singularity dynamics in curvature collapse and jet eruption on a fluid surface

Finite-time singularities--local divergences in the amplitude or gradient of a physical observable at a particular time--occur in a diverse range of physical systems. Examples include singularities capable of damaging optical fibres and lasers in nonlinear optical systems, and gravitational singularities associated with black holes. In fluid systems, the formation of finite-time singularities cause spray and air-bubble entrainment, processes which influence air-sea interaction on a global scale. Singularities driven by surface tension have been studied in the break-up of pendant drops and liquid sheets. Here we report a theoretical and experimental study of the generation of a singularity by inertial focusing, in which no break-up of the fluid surface occurs. Inertial forces cause a collapse of the surface that leads to jet formation; our analysis, which includes surface tension effects, predicts that the surface profiles should be describable by a single universal exponent. These theoretical predictions correlate closely with our experimental measurements of a collapsing surface singularity. The solution can be generalized to apply to a broad class of singular phenomena.

Journal Article↗

PubMed2000

Two-mode rhomboidal states in driven surface waves

Two-mode rhomboid patterns are generated experimentally via two-frequency parametric forcing of surface waves. These patterns are formed by the simple nonlinear resonance: k-->'2-k-->(2) = k-->(1) where k(1) and k(2)( = k(')(2)) are concurrently excited eigenmodes. The state possesses a direction-dependent time dependence described by a superposition of the two modes, and a dimensionless scaling delineating the state's region of existence is presented. We also show that 2n-fold quasipatterns naturally arise from these states when the coupling angle between k-->(2) and k-->'2 is 2pi/n.

Journal Article↗

PubMed2000

Perception of musical tension for nontonal orchestral timbres and its relation to psychoacoustic roughness.

Can tension in nontonal music be expressed without dynamic or rhythmic cues? Perceptual theories of tonal harmony predict that psychoacoustic roughness plays an important role in the perception of this tension. We chose a set of orchestrated chords from a nontonal piece and investigated listeners' judgments of musical tension and roughness. Paired comparisons yielded psychophysical scales of tension and roughness. Two experiments established distinct levels of these two attributes across chords. A model simulation reproduced the experimental roughness measures. The results indicate that nontonal tension could be perceived consistently on the basis of timbral differences and that it was correlated with roughness, the correlation being stronger as the perceptual salience of other attributes (such as high-pitched tones or tonal intervals) was reduced.

Adolescent↗

PubMed1997

Covalent attachment of DNA oligonucleotides to glass.

A method for synthesizing DNA directly on glass is presented. The process is based on pretreatment of glass with boiling hydrochloric acid, thus exposing the hydroxyl groups of the glass. Phosphite-triester chemistry was used to directly attach the first nucleotide to a glass plate via a covalent bond between the hydroxyl group of the glass and the phosphate group of the protected deoxyribonucleotide. Standard molecular biology procedures, such as ligation and restriction digest, were efficiently performed on the glass synthesized oligonucleotide, with the added benefit of extreme ease of handling.

Biotechnology↗

PubMed1996