Showing papers by "Lawrence Berkeley National Laboratory published in 1999"
University of California, Berkeley1, Lawrence Berkeley National Laboratory2, Instituto Superior Técnico3, Pierre-and-Marie-Curie University4, Stockholm University5, European Southern Observatory6, Collège de France7, University of Cambridge8, University of Barcelona9, Yale University10, Space Telescope Science Institute11, European Space Agency12, University of New South Wales13
TL;DR: In this paper, the mass density, Omega_M, and cosmological-constant energy density of the universe were measured using the analysis of 42 Type Ia supernovae discovered by the Supernova Cosmology project.
Abstract: We report measurements of the mass density, Omega_M, and
cosmological-constant energy density, Omega_Lambda, of the universe based on
the analysis of 42 Type Ia supernovae discovered by the Supernova Cosmology
Project. The magnitude-redshift data for these SNe, at redshifts between 0.18
and 0.83, are fit jointly with a set of SNe from the Calan/Tololo Supernova
Survey, at redshifts below 0.1, to yield values for the cosmological
parameters. All SN peak magnitudes are standardized using a SN Ia lightcurve
width-luminosity relation. The measurement yields a joint probability
distribution of the cosmological parameters that is approximated by the
relation 0.8 Omega_M - 0.6 Omega_Lambda ~= -0.2 +/- 0.1 in the region of
interest (Omega_M <~ 1.5). For a flat (Omega_M + Omega_Lambda = 1) cosmology we
find Omega_M = 0.28{+0.09,-0.08} (1 sigma statistical) {+0.05,-0.04}
(identified systematics). The data are strongly inconsistent with a Lambda = 0
flat cosmology, the simplest inflationary universe model. An open, Lambda = 0
cosmology also does not fit the data well: the data indicate that the
cosmological constant is non-zero and positive, with a confidence of P(Lambda >
0) = 99%, including the identified systematic uncertainties. The best-fit age
of the universe relative to the Hubble time is t_0 = 14.9{+1.4,-1.1} (0.63/h)
Gyr for a flat cosmology. The size of our sample allows us to perform a variety
of statistical tests to check for possible systematic errors and biases. We
find no significant differences in either the host reddening distribution or
Malmquist bias between the low-redshift Calan/Tololo sample and our
high-redshift sample. The conclusions are robust whether or not a
width-luminosity relation is used to standardize the SN peak magnitudes.
16,838 citations
TL;DR: An overview of the Bro system's design, which emphasizes high-speed (FDDI-rate) monitoring, real-time notification, clear separation between mechanism and policy, and extensibility, is given.
2,236 citations
TL;DR: The progress in applying single-molecule detection and single-Molecule spectroscopy at room temperature by laser-induced fluorescence with the use of fluorophores that are site-specifically attached to macromolecules is reviewed.
Abstract: Recent advances in single-molecule detection and single-molecule spectroscopy at room temperature by laser-induced fluorescence offer new tools for the study of individual macromolecules under physiological conditions. These tools relay conformational states, conformational dynamics, and activity of single biological molecules to physical observables, unmasked by ensemble averaging. Distributions and time trajectories of these observables can therefore be measured during a reaction without the impossible need to synchronize all the molecules in the ensemble. The progress in applying these tools to biological studies with the use of fluorophores that are site-specifically attached to macromolecules is reviewed.
2,053 citations
TL;DR: In this article, the Tamm-Dancoff approximation to time-dependent density functional theory is proposed and implemented for molecular excited states, which yields excitation energies for several closed-and open-shell molecules that are essentially of the same quality as those obtained from time dependent density functional theories itself, when the same exchange correlation functional is used.
1,617 citations
TL;DR: In this paper, the authors present evidence for a strong interaction between the conduction band and a narrow resonant band formed by nitrogen states in alloys, which leads to a splitting of conduction bands into two subbands and a reduction of the fundamental band gap.
Abstract: We present evidence for a strong interaction between the conduction band and a narrow resonant band formed by nitrogen states in $\mathrm{Ga}{}_{1\ensuremath{-}x}\mathrm{In}{}_{x}\mathrm{N}{}_{y}\mathrm{As}{}_{1\ensuremath{-}y}$ alloys. The interaction leads to a splitting of the conduction band into two subbands and a reduction of the fundamental band gap. An anticrossing of the extended states of the conduction band of the $\mathrm{Ga}{}_{1\ensuremath{-}x}\mathrm{In}{}_{x}\mathrm{As}$ matrix and the localized nitrogen resonant states is used to model the interaction. Optical transitions associated with the energy minima of the two subbands and the characteristic anticrossing behavior of the transitions under applied hydrostatic pressure have been unambiguously observed using photomodulation spectroscopy. The experimental results are in excellent quantitative agreement with the model.
1,452 citations
TL;DR: In this article, the authors present measurements of the conductance of single-walled carbon nanotubes (SWNTs) as a function of temperature and voltage that agree with predictions for tunnelling into a Luttinger liquid.
Abstract: Electron transport in conductors is usually well described by Fermi-liquid theory, which assumes that the energy states of the electrons near the Fermi level EF are not qualitatively altered by Coulomb interactions. In one-dimensional systems, however, even weak Coulomb interactions cause strong perturbations. The resulting system, known as a Luttinger liquid, is predicted to be distinctly different from its two- and three-dimensional counterparts1. For example, tunnelling into a Luttinger liquid at energies near the Fermi level is predicted to be strongly suppressed, unlike in two- and three-dimensional metals. Experiments on one-dimensional semiconductor wires2, 2,3 have been interpreted by using Luttinger-liquid theory, but an unequivocal verification of the theoretical predictions has not yet been obtained. Similarly, the edge excitations seen in fractional quantum Hall conductors are consistent with Luttinger-liquid behaviour4, 5, but recent experiments failed to confirm the predicted relationship between the electrical properties of the bulk state and those of the edge states6. Electrically conducting single-walled carbon nanotubes (SWNTs) represent quantum wires7,8,9,10 that may exhibit Luttinger-liquid behaviour11, 12. Here we present measurements of the conductance of bundles (‘ropes’) of SWNTs as a function of temperature and voltage that agree with predictions for tunnelling into a Luttinger liquid. In particular, we find that the conductance and differential conductance scale as power laws with respect to temperature and bias voltage, respectively, and that the functional forms and the exponents are in good agreement with theoretical predictions.
1,251 citations
TL;DR: It is shown that PIK3CA is frequently increased in copy number in ovarian cancers, that the increased copy number is associated with increased Pik3CA transcription, p110α protein expression and PI3-kinase activity and that treatment with the PI3 -kinase inhibitor LY294002 decreases proliferation and increases apoptosis.
Abstract: Ovarian cancer is the leading cause of death from gynecological malignancy and the fourth leading cause of cancer death among American women, yet little is known about its molecular aetiology. Studies using comparative genomic hybridization (CGH) have revealed several regions of recurrent, abnormal, DNA sequence copy number that may encode genes involved in the genesis or progression of the disease. One region at 3q26 found to be increased in copy number in approximately 40% of ovarian and others cancers contains PIK3CA, which encodes the p110alpha catalytic subunit of phosphatidylinositol 3-kinase (PI3-kinase). The association between PIK3CA copy number and PI3-kinase activity makes PIK3CA a candidate oncogene because a broad range of cancer-related functions have been associated with PI3-kinase mediated signalling. These include proliferation, glucose transport and catabolism, cell adhesion, apoptosis, RAS signalling and oncogenic transformation. In addition, downstream effectors of PI3-kinase, AKT1 and AKT2, have been found to be amplified or activated in human tumours, including ovarian cancer. We show here that PIK3CA is frequently increased in copy number in ovarian cancers, that the increased copy number is associated with increased PIK3CA transcription, p110alpha protein expression and PI3-kinase activity and that treatment with the PI3-kinase inhibitor LY294002 decreases proliferation and increases apoptosis. Our observations suggest PIK3CA is an oncogene that has an important role in ovarian cancer.
1,179 citations
TL;DR: In this article, the authors investigated hadron-hadron (h-h) collisions at high energies in the ultra-relativistic quantum molecular dynamics (UrQMD) approach.
Abstract: Hadron-hadron (h-h) collisions at high energies are investigated in the ultra-relativistic quantum molecular dynamics (UrQMD) approach. This microscopic transport model describes the phenomenology of hadronic interactions at low and intermediate energies ( 5 GeV, the excitation of colour strings and their subsequent fragmentation into hadrons dominates the multiple production of particles in the UrQMD model. The model shows a fair overall agreement with a large body of experimental h-h data over a wide range of h-h centre-of-mass energies. Hadronic reaction data with higher precision would be useful to support the use of the UrQMD model for relativistic heavy-ion collisions.
1,151 citations
TL;DR: A high-resolution model of the microtubule has been obtained by docking the crystal structure of tubulin into a 20 A map of themicrotubule, and the excellent fit indicates the similarity of the tubulin conformation in both polymers and defines the orientation of the Tubulin structure within the micro Tubule.
1,135 citations
TL;DR: In this article, the authors measured the temperature-dependent thermal conductivity of single-walled carbon nanotubes from 350 K to 8 K and showed that the thermal conductivities are dominated by phonons at all temperatures.
Abstract: We have measured the temperature-dependent thermal conductivity $\ensuremath{\kappa}(T)$ of crystalline ropes of single-walled carbon nanotubes from 350 K to 8 K. $\ensuremath{\kappa}(T)$ decreases smoothly with decreasing temperature, and displays linear temperature dependence below 30 K. Comparison with electrical conductivity experiments indicates that the room-temperature thermal conductivity of a single nanotube may be comparable to that of diamond or in-plane graphite, while the ratio of thermal to electrical conductance for a given sample indicates that the thermal conductivity is dominated by phonons at all temperatures. Below 30 K, the linear temperature dependence and estimated magnitude of $\ensuremath{\kappa}(T)$ imply an energy-independent phonon mean free path of \ensuremath{\sim}0.5--1.5 \ensuremath{\mu}m.
1,108 citations
TL;DR: The cosmic triangle as mentioned in this paper is a way of representing the past, present, and future status of the universe and its current location within the cosmic triangle is determined by the answers to three questions: How much matter is in the universe? Is the expansion rate slowing down or speeding up? And, is the universe flat?
Abstract: The cosmic triangle is introduced as a way of representing the past, present, and future status of the universe. Our current location within the cosmic triangle is determined by the answers to three questions: How much matter is in the universe? Is the expansion rate slowing down or speeding up? And, is the universe flat? A review of recent observations suggests a universe that is lightweight (matter density about one-third the critical value), is accelerating, and is flat. The acceleration implies the existence of cosmic dark energy that overcomes the gravitational self-attraction of matter and causes the expansion to speed up.
TL;DR: Many molecules that control genetic regulatory circuits act at extremely low intracellular concentrations, which causes large random variation in rates of development, morphology and the instantaneous concentration of each molecular species in each cell.
TL;DR: The prevalence of unusual network events such as out-of-order delivery and packet replication are characterized and a robust receiver-based algorithm for estimating "bottleneck bandwidth" is discussed that addresses deficiencies discovered in techniques based on "packet pair".
Abstract: We discuss findings from a large-scale study of Internet packet dynamics conducted by tracing 20000 TCP bulk transfers between 35 Internet sites. Because we traced each 100-kbyte transfer at both the sender and the receiver, the measurements allow us to distinguish between the end-to-end behavior due to the different directions of the Internet paths, which often exhibit asymmetries. We: (1) characterize the prevalence of unusual network events such as out-of-order delivery and packet replication; (2) discuss a robust receiver-based algorithm for estimating "bottleneck bandwidth" that addresses deficiencies discovered in techniques based on "packet pair;" (3) investigate patterns of packet loss, finding that loss events are not well modeled as independent and, furthermore, that the distribution of the duration of loss events exhibits infinite variance; and (4) analyze variations in packet transit delays as indicators of congestion periods, finding that congestion periods also span a wide range of time scales.
TL;DR: P phenotypically normal mammary epithelial cells with tetracycline-regulated expression of MMP3/stromelysin-1 (Str1) form epithelial glandular structures in vivo without Str1 but form invasive mesenchymal-like tumors with Str1, indicating that Str1 influences tumor initiation and alters neoplastic risk.
TL;DR: These mice demonstrate that initial neuronal cytoplasmic toxicity is followed by cleavage of htt, nuclear translocation of htt N-terminal fragments, and selective neurodegeneration, clearly showing that aggregates are not essential to initiation of neuronal death.
TL;DR: In this article, the authors examined the mechanisms of fatigue-crack propagation with particular emphasis on the similarities and differences between cyclic crack growth in ductile materials such as metals, and corresponding behavior in brittle materials, such as intermetallics and ceramics.
Abstract: The mechanisms of fatigue-crack propagation are examined with particular emphasis on the similarities and differences between cyclic crack growth in ductile materials, such as metals, and corresponding behavior in brittle materials, such as intermetallics and ceramics. This is achieved by considering the process of fatigue-crack growth as a mutual competition between intrinsic mechanisms of crack advance ahead of the crack tip (e.g., alternating crack-tip blunting and resharpening), which promote crack growth, and extrinsic mechanisms of crack-tip shielding behind the tip (e.g., crack closure and bridging), which impede it. The widely differing nature of these mechanisms in ductile and brittle materials and their specific dependence upon the alternating and maximum driving forces (e.g., ΔK andK
max) provide a useful distinction of the process of fatigue-crack propagation in different classes of materials; moreover, it provides a rationalization for the effect of such factors as load ratio and crack size. Finally, the differing susceptibility of ductile and brittle materials to cyclic degradation has broad implications for their potential structural application; this is briefly discussed with reference to lifetime prediction.
TL;DR: Almost all studies found that ventilation rates below 10 Ls-1 per person in all building types were associated with statistically significant worsening in one or more health or perceived air quality outcomes, and carbon dioxide concentrations below 800 ppm supported these findings.
Abstract: This paper reviews current literature on the associations of ventilation rates and carbon dioxide concentrations in non-residential and non-industrial buildings (primarily offices) with health and other human outcomes. Twenty studies, with close to 30,000 subjects, investigated the association of ventilation rates with human responses, and 21 studies, with over 30,000 subjects, investigated the association of carbon dioxide concentration with these responses. Almost all studies found that ventilation rates below 10 Ls -1 per person in all building types were associated with statistically significant worsening in one or more health or perceived air quality outcomes. Some studies determined that increases in ventilation rates above 10 Ls -1 per person, up to approximately 20 Ls -1 per person, were associated with further significant decreases in the prevalence of SBS symptoms or with further significant improvements in perceived air quality. The carbon dioxide studies support these findings. About half of the carbon dioxide studies suggest that the risk of sick building syndrome symptoms continued to decrease significantly with decreasing carbon dioxide concentrations below 800 ppm. The ventilation studies reported relative risks of 1.5 - 2 for respiratory illnesses and 1.1 - 6 for sick building syndrome symptoms for low compared to high ventilation rates.
TL;DR: Second-order nonlinear optics can be used to quantitatively determine the orientation of chemical bonds or submoieties of a fairly complicated molecule at an interface, and therefore completely map out its orientation and conformation as mentioned in this paper.
Abstract: Second-order nonlinear optics can be used to quantitatively determine the orientation of chemical bonds or submoieties of a fairly complicated molecule at an interface, and therefore completely map out its orientation and conformation. As a specific example, we have studied pentyl-cyanoterphenyl molecules at the air-water interface. We have measured the orientation of all three parts of the molecule (cyano head group, terphenyl ring, and pentyl chain) by optical second-harmonic generation and infrared-visible sum-frequency generation. A quantitatively consistent picture of the molecular configuration has been obtained. The technique can be applied to situations where other methods would fail (e.g., the surface of neat liquids or buried interfaces).
TL;DR: Cloning the chromosome 19q13 breakpoint in a patient with a reciprocal X;19 chromosome translocation identified mutations in RPS19 in 10 of 40 unrelated DBA patients, including nonsense, frameshift, splice site and missense mutations, as well as two intragenic deletions that suggest a function for R PS19 in erythropoiesis and embryogenesis.
Abstract: Diamond-Blackfan anaemia (DBA) is a constitutional erythroblastopenia characterized by absent or decreased erythroid precursors. The disease, previously mapped to human chromosome 19q13, is frequently associated with a variety of malformations. To identify the gene involved in DBA, we cloned the chromosome 19q13 breakpoint in a patient with a reciprocal X;19 chromosome translocation. The breakpoint occurred in the gene encoding ribosomal protein S19. Furthermore, we identified mutations in RPS19 in 10 of 40 unrelated DBA patients, including nonsense, frameshift, splice site and missense mutations, as well as two intragenic deletions. These mutations are associated with clinical features that suggest a function for RPS19 in erythropoiesis and embryogenesis.
TL;DR: In this article, it was shown that the Wilson loop of the large N gauge theory with supersymmetry in four dimensions is described by a minimal surface in the AdS-CFT correspondence.
Abstract: The AdS-CFT correspondence suggests that the Wilson loop of the large N gauge theory with $\mathcal{N}=4$ supersymmetry in four dimensions is described by a minimal surface in ${\mathrm{AdS}}_{5}\ifmmode\times\else\texttimes\fi{}{\mathrm{S}}^{5}.$ We examine various aspects of this proposal, comparing gauge theory expectations with computations of minimal surfaces. There is a distinguished class of loops, which we call BPS loops, whose expectation values are free from ultraviolet divergence. We formulate the loop equation for such loops. To the extent that we have checked, the minimal surface in ${\mathrm{AdS}}_{5}\ifmmode\times\else\texttimes\fi{}{\mathrm{S}}^{5}$ gives a solution of the equation. We also discuss the zigzag symmetry of the loop operator. In the $\mathcal{N}=4$ gauge theory, we expect the zigzag symmetry to hold when the loop does not couple the scalar fields in the supermultiplet. We will show how this is realized for the minimal surface.
TL;DR: Recent experimental and computational studies that take advantage of new methodologies and basic insights derived from the study of concentrated ionic solutions have begun to clarify the structure of electrical double layers formed on hydrated clay mineral surfaces, particularly those in the interlayer region of swelling 2:1 layer type clay minerals.
Abstract: Clay minerals are layer type aluminosilicates that figure in terrestrial biogeochemical cycles, in the buffering capacity of the oceans, and in the containment of toxic waste materials. They are also used as lubricants in petroleum extraction and as industrial catalysts for the synthesis of many organic compounds. These applications derive fundamentally from the colloidal size and permanent structural charge of clay mineral particles, which endow them with significant surface reactivity. Unraveling the surface geochemistry of hydrated clay minerals is an abiding, if difficult, topic in earth sciences research. Recent experimental and computational studies that take advantage of new methodologies and basic insights derived from the study of concentrated ionic solutions have begun to clarify the structure of electrical double layers formed on hydrated clay mineral surfaces, particularly those in the interlayer region of swelling 2:1 layer type clay minerals. One emerging trend is that the coordination of interlayer cations with water molecules and clay mineral surface oxygens is governed largely by cation size and charge, similarly to a concentrated ionic solution, but the location of structural charge within a clay layer and the existence of hydrophobic patches on its surface provide important modulations. The larger the interlayer cation, the greater the influence of clay mineral structure and hydrophobicity on the configurations of adsorbed water molecules. This picture extends readily to hydrophobic molecules adsorbed within an interlayer region, with important implications for clay–hydrocarbon interactions and the design of catalysts for organic synthesis.
TL;DR: This work couple the level set scheme to an adaptive projection method for the incompressible Navier?Stokes equations, in order to achieve higher resolution of the free surface with a minimum of additional expense.
TL;DR: In this article, the authors evaluated the shear modulus of various transition-metal carbides and nitrides using ab initio pseudopotential calculations and showed that the behavior of these materials can be understood on a fundamental level in terms of their electronic band structure.
Abstract: Transition-metal carbides and nitrides are hard materials widely used for cutting tools and wear-resistant coatings. Their hardness is not yet understood at a fundamental level. A clue may lie in the puzzling fact that transition-metal carbonitrides that have the rock-salt structure (such as TiCxN1−x) have the greatest hardness for a valence-electron concentration of about 8.4 per cell1,2,3, which suggests that the hardness may be determined more by the nature of the bonding than by the conventional microstructural features that determine the hardness of structural metals and alloys. To investigate this possibility, we have evaluated the shear modulus of various transition-metal carbides and nitrides using ab initio pseudopotential calculations. Our results show that the behaviour of these materials can be understood on a fundamental level in terms of their electronic band structure. The unusual hardness originates from a particular band of σ bonding states between the non-metal p orbitals and the metal d orbitals that strongly resists shearing strain or shape change. Filling of these states is completed at a valence-electron concentration of about 8.4, and any additional electrons would go into a higher band which is unstable against shear deformations.
TL;DR: Structures of 70S ribosome complexes containing messenger RNA and transfer RNA (tRNA), or tRNA analogs, have been solved by x-ray crystallography at up to 7.8 angstrom resolution.
Abstract: Structures of 70S ribosome complexes containing messenger RNA and transfer RNA (tRNA), or tRNA analogs, have been solved by x-ray crystallography at up to 7.8 angstrom resolution. Many details of the interactions between tRNA and the ribosome, and of the packing arrangements of ribosomal RNA (rRNA) helices in and between the ribosomal subunits, can be seen. Numerous contacts are made between the 30S subunit and the P-tRNA anticodon stem-loop; in contrast, the anticodon region of A-tRNA is much more exposed. A complex network of molecular interactions suggestive of a functional relay is centered around the long penultimate stem of 16S rRNA at the subunit interface, including interactions involving the “switch” helix and decoding site of 16S rRNA, and RNA bridges from the 50S subunit.
TL;DR: It is suggested that TRF1 is insufficient for control of telomere length in human cells, and that TIN2 is an essential mediator of TRF 1 function.
Abstract: Telomeres are DNA-protein structures that cap linear chromosomes and are essential for maintaining genomic stability and cell phenotype. We identified a novel human telomere-associated protein, TIN2, by interaction cloning using the telomeric DNA-binding-protein TRF1 as a bait. TIN2 interacted with TRF1 in vitro and in cells, and co-localized with TRF1 in nuclei and metaphase chromosomes. A mutant TIN2 that lacks amino-terminal sequences effects elongated human telomeres in a telomerase-dependent manner. Our findings suggest that TRF1 is insufficient for control of telomere length in human cells, and that TIN2 is an essential mediator of TRF1 function.
TL;DR: The sum-frequency generation (SFG) technique has been shown to be the only technique available that can provide detailed information about a liquid interface at the molecular level as mentioned in this paper, which has been proven to be a most powerful analytical tool for liquid interfaces.
Abstract: Liquid interfaces play a fundamental role in science and technology. The development of surface-sensitive probes capable of yielding molecular information about these interfaces is of great importance. This paper gives an overview of our and some others' recent work on vibrational spectroscopy of liquid interfaces by the sum-frequency generation (SFG) technique. This technique, being highly surface specific and applicable to all interfaces accessible by light, has been proven to be a most powerful analytical tool for liquid interfaces. A wide range of systems have been studied including neat liquid surfaces, solid/liquid and liquid/liquid interfaces, surfactants at liquid interfaces, and electrochemical interfaces. In many cases, SFG is shown to be the only technique available that can provide detailed information about a liquid interface at the molecular level.
TL;DR: The denaturation of a DNA hairpin was examined by using single-pair FRET to measure intramolecular distances and identify subpopulations of freely diffusing macromolecules in a heterogeneous ensemble.
Abstract: Photon bursts from single diffusing donor-acceptor labeled macromolecules were used to measure intramolecular distances and identify subpopulations of freely diffusing macromolecules in a heterogeneous ensemble. By using DNA as a rigid spacer, a series of constructs with varying intramolecular donor-acceptor spacings were used to measure the mean and distribution width of fluorescence resonance energy transfer (FRET) efficiencies as a function of distance. The mean single-pair FRET efficiencies qualitatively follow the distance dependence predicted by Forster theory. Possible contributions to the widths of the FRET efficiency distributions are discussed, and potential applications in the study of biopolymer conformational dynamics are suggested. The ability to measure intramolecular (and intermolecular) distances for single molecules implies the ability to distinguish and monitor subpopulations of molecules in a mixture with different distances or conformational states. This is demonstrated by monitoring substrate and product subpopulations before and after a restriction endonuclease cleavage reaction. Distance measurements at single-molecule resolution also should facilitate the study of complex reactions such as biopolymer folding. To this end, the denaturation of a DNA hairpin was examined by using single-pair FRET.
TL;DR: The experimental methods demonstrated here should prove generally useful in studies of protein folding and enzyme catalysis at single-molecule resolution.
Abstract: Fluorescence resonance energy transfer and fluorescence polarization anisotropy are used to investigate single molecules of the enzyme staphylococcal nuclease. Intramolecular fluorescence resonance energy transfer and fluorescence polarization anisotropy measurements of fluorescently labeled staphylococcal nuclease molecules reveal distinct patterns of fluctuations that may be attributed to protein conformational dynamics on the millisecond time scale. Intermolecular fluorescence resonance energy transfer measurements provide information about the dynamic interactions of staphylococcal nuclease with single substrate molecules. The experimental methods demonstrated here should prove generally useful in studies of protein folding and enzyme catalysis at single-molecule resolution.
TL;DR: In this paper, the authors investigated the dynamics of light propagation in a cell with antirelaxation wall coating and found that the observed dynamics are analogous to those in electromagnetically induced transparency.
Abstract: The dynamics of resonant light propagation in rubidium vapor in a cell with antirelaxation wall coating are investigated. We change the polarization of the input light and measure the time dependence of the polarization after the cell. The observed dynamics are shown to be analogous to those in electromagnetically induced transparency. Spectral dependence of light pulse delays is found to be similar to that of nonlinear magneto-optic rotation. Delays up to [approx]13 ms are observed, corresponding to a 8 m/s group velocity. Fields of a few microgauss are used to control the group velocity. [copyright] [ital 1999] [ital The American Physical Society ]