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PubMedDate not supplied

Dissociation of normal feature analysis and deficient processing of letter-strings in dyslexic adults.

Neuroimaging studies have revealed that the functional organization of reading differs between developmentally dyslexic and non-impaired individuals. However, it is not clear how early in the reading process the differences between fluent and dyslexic readers start to emerge. We studied cortical activity of ten dyslexic adults using magnetoencephalography (MEG), as they silently read words or viewed symbol-strings which were clearly visible or degraded with Gaussian noise. This method has previously been used to dissociate between analysis of local features and pre-lexical word processing in fluent adult readers. Signals peaking around 100 ms after stimulus onset and originating in the postero-medial extrastriate cortex were associated with increasing local luminance contrast in the noise patches. These early visual responses were similar in dyslexic and non-impaired readers. In contrast, the letter-string-specific responses peaking around 150 ms predominantly in the left inferior occipito-temporal cortex in fluent readers were undetectable in dyslexic readers. Thus, while the early visual processing seems intact in dyslexic adults, the pattern of cortical activation starts to differ from that of fluent readers at the point where letter-string-specific signals first emerge during reading.

Adult↗

PubMed2003

STRING: a database of predicted functional associations between proteins.

Functional links between proteins can often be inferred from genomic associations between the genes that encode them: groups of genes that are required for the same function tend to show similar species coverage, are often located in close proximity on the genome (in prokaryotes), and tend to be involved in gene-fusion events. The database STRING is a precomputed global resource for the exploration and analysis of these associations. Since the three types of evidence differ conceptually, and the number of predicted interactions is very large, it is essential to be able to assess and compare the significance of individual predictions. Thus, STRING contains a unique scoring-framework based on benchmarks of the different types of associations against a common reference set, integrated in a single confidence score per prediction. The graphical representation of the network of inferred, weighted protein interactions provides a high-level view of functional linkage, facilitating the analysis of modularity in biological processes. STRING is updated continuously, and currently contains 261 033 orthologs in 89 fully sequenced genomes. The database predicts functional interactions at an expected level of accuracy of at least 80% for more than half of the genes; it is online at http://www.bork.embl-heidelberg.de/STRING/.

Algorithms↗

PubMed2005

STRING: known and predicted protein-protein associations, integrated and transferred across organisms.

A full description of a protein's function requires knowledge of all partner proteins with which it specifically associates. From a functional perspective, 'association' can mean direct physical binding, but can also mean indirect interaction such as participation in the same metabolic pathway or cellular process. Currently, information about protein association is scattered over a wide variety of resources and model organisms. STRING aims to simplify access to this information by providing a comprehensive, yet quality-controlled collection of protein-protein associations for a large number of organisms. The associations are derived from high-throughput experimental data, from the mining of databases and literature, and from predictions based on genomic context analysis. STRING integrates and ranks these associations by benchmarking them against a common reference set, and presents evidence in a consistent and intuitive web interface. Importantly, the associations are extended beyond the organism in which they were originally described, by automatic transfer to orthologous protein pairs in other organisms, where applicable. STRING currently holds 730,000 proteins in 180 fully sequenced organisms, and is available at http://string.embl.de/.

Databases, Protein↗

PubMed2006

STRING 7--recent developments in the integration and prediction of protein interactions.

Information on protein-protein interactions is still mostly limited to a small number of model organisms, and originates from a wide variety of experimental and computational techniques. The database and online resource STRING generalizes access to protein interaction data, by integrating known and predicted interactions from a variety of sources. The underlying infrastructure includes a consistent body of completely sequenced genomes and exhaustive orthology classifications, based on which interaction evidence is transferred between organisms. Although primarily developed for protein interaction analysis, the resource has also been successfully applied to comparative genomics, phylogenetics and network studies, which are all facilitated by programmatic access to the database backend and the availability of compact download files. As of release 7, STRING has almost doubled to 373 distinct organisms, and contains more than 1.5 million proteins for which associations have been pre-computed. Novel features include AJAX-based web-navigation, inclusion of additional resources such as BioGRID, and detailed protein domain annotation. STRING is available at http://string.embl.de/

Databases, Protein↗

PubMed1996

Versatility of the subcuticular purse-string suture in wound closure.

This paper presents a useful extension of the purse-string continuous subcuticular suture technique for management of circular or oval wounds. This strategy can provide primary skin closure in small defects. It can be used in large skin defects, reducing the amount of skin graft required. In large composite defects, it can reduce the size of the flap. The purse-string can be applied to elliptical defects as well as circular ones and can be employed in all regions of the body. The versatility of the subcuticular purse-string suture in wound closure has been demonstrated.

Dermatologic Surgical Procedures↗

PubMed2000

Renormalization group analysis of a quivering string model of posture control.

Scaling concepts and renormalization group methods are applied to a simple linear model of human posture control consisting of a trembling or quivering string subject to damping and restoring forces. The string is driven by uncorrelated white Gaussian noise, intended to model the corrections of the physiological control system. We find that adding a weak quadratic nonlinearity to the posture control model opens up a rich and complicated phase space (representing the dynamics) with various nontrivial fixed points and basins of attraction. The transition from diffusive to saturated regimes of the linear model is understood as a crossover phenomenon, and the robustness of the linear model with respect to weak nonlinearities is confirmed. Correlations in posture fluctuations are obtained in both time and space domains. There is an attractive fixed point identified with falling. The scaling of the correlations in the front-back displacement, which can be measured in the laboratory, is predicted for both large-separation (along the string) and long-time regimes of posture control.

Humans↗

PubMed2001

Percolation, Bose-Einstein condensation, and string proliferation.

The close analogy between cluster percolation and string proliferation in the context of critical phenomena is studied. Like clusters in percolation theory, closed strings, which can be either finite-temperature worldlines or topological line defects, are described by a distribution parametrized by only two exponents. On approaching the critical point, the string tension vanishes and the loops proliferate, thereby signalling the onset of Bose-Einstein condensation (in the case of worldlines) or the disordering of the ordered state (in the case of vortices). The ideal Bose gas with modified energy spectrum is used as a stepping stone to derive general expressions for the critical exponents in terms of the two exponents parametrizing the loop distribution near criticality.

Journal Article↗

PubMed2004

Roughness of a tilted anharmonic string at depinning.

We consider the discretized model of a driven string with an anharmonic elastic energy, in a two-dimensional random potential, as introduced by [Phys. Rev. Lett. 87, 187002 (2001)]]. Using finite size scaling, we numerically compute the roughness of the string in a uniform applied force at the critical depinning threshold. By considering a string with a net average tilt, we demonstrate that the anharmonic elastic energy crosses the model over to the quenched KPZ universality class, in agreement with recent theoretical predictions.

Journal Article↗

PubMed2000

Matrix theory interpretation of discrete light cone quantization string worldsheets

We study the null compactification of type-IIA string perturbation theory at finite temperature. We prove a theorem about Riemann surfaces establishing that the moduli spaces of infinite-momentum-frame superstring worldsheets are identical to those of branched-cover instantons in the matrix-string model conjectured to describe M theory. This means that the identification of string degrees of freedom in the matrix model proposed by Dijkgraaf, Verlinde, and Verlinde is correct and that its natural generalization produces the moduli space of Riemann surfaces at all orders in the genus expansion.

Journal Article↗

PubMed2001

String formation in sheared polymer blends: coalescence, breakup, and finite size effects.

We have discovered a droplet-string transition in concentrated polymer blends which occurs when the size of the dispersed droplets becomes comparable to the gap width between the shearing surfaces. The transition is abrupt and proceeds via the coalescence of droplets in a four-stage kinetic process. Once formed, the strings are stable and exhibit pronounced hysteresis. The string state is stabilized by a suppression of the Rayleigh-Tomotika instability due to both finite size effects and to the shear-induced advection of small-amplitude disturbances.

Journal Article↗

PubMed2001

Consequences of parton saturation and string percolation on the development of cosmic ray showers.

At high gluon or string densities, gluon saturation or the strong interaction among strings, either forming color ropes or giving rise to string percolation, induces a strong suppression in the particle multiplicities produced at high energy. This suppression implies important modifications on cosmic ray shower development. In particular, it is shown that it affects the depth of maximum, the elongation rate, and the behavior of the number of muons at energies about 10(17)--10(18) eV. The existing cosmic ray data point out in the same direction.

Journal Article↗

PubMed2001

Deconfinement and the Hagedorn transition in string theory.

We introduce a new definition of the thermal partition function in string theory. With this new definition, the thermal partition functions of all of the string theories obey thermal duality relations with self-dual Hagedorn temperature beta(2)(H) = 4pi(2)alpha('). A beta-->beta(2)(H)/beta transformation maps the type I theory into a new string theory (type I) with thermal D p-branes, spatial hypersurfaces supporting a p-dimensional finite temperature non-Abelian Higgs-gauge theory for p< or =9. We demonstrate a continuous phase transition in the behavior of the static heavy quark-antiquark potential for small separations r(2)(*)<<alpha(') transitioning through a precise inverse power law at a critical temperature T(D) = T(H)r(*)/(2alpha('))(1/2)pi.

Journal Article↗

PubMed2001

Multiple Coulomb ordered strings of ions in a storage ring.

We explain that the anomalous frequency shifts of very close masses obtained in the high precision mass measurement experiments in the ESR storage ring result from the locking of Coulomb interacting strings of ions. Here two concentric strings which run horizontally close to each other are captured into a single string if their thermal clouds overlap and give up their identity.

Journal Article↗

PubMed2002

Bound states of string networks and D-branes.

We show the existence of nonthreshold bound states of (p,q) string networks and D3-branes, preserving 1/4 of the full type-IIB supersymmetry, interpreted as string networks "dissolved" in D3-branes. We also explicitly write down the expression for the mass density of the system and discuss the extension of the construction to other Dp-branes. Differences in our construction of string networks with the ones interpreted as dyons in N = 4 gauge theories are also pointed out.

Journal Article↗

PubMed2002

QCD-like behavior of high-temperature confining strings.

We show that, contrary to previous string models, the high-temperature behavior of the recently proposed confining strings reproduces exactly the correct large- N QCD result, a necessary condition for any string model of confinement.

Journal Article↗

PubMed2002

String interactions in a plane-fronted parallel-wave spacetime.

We argue that string interactions in a plane-fronted parallel-wave spacetime are governed by an effective coupling g(eff)=g(s)(micro p(+)alpha('))f(micro p(+)alpha(')) where f(microp(+)alpha(')) is proportional to the light-cone energy of the string states involved in the interaction. This simply follows from generalities of a matrix string description of this background. g(eff) nicely interpolates between the expected result (g(s)) for flat space (small micro p(+)alpha(')) and a recently conjectured expression from the perturbative gauge theory side (large micro p(+)alpha(')).

Journal Article↗

PubMed2003

Hadronic density of states from string theory.

We present an exact calculation of the finite temperature partition function for the hadronic states corresponding to a Penrose-Güven limit of the Maldacena-Nùñez embedding of the N=1 super Yang-Mills (SYM) into string theory. It is established that the theory exhibits a Hagedorn density of states. We propose a semiclassical string approximation to the finite temperature partition function for confining gauge theories admitting a supergravity dual, by performing an expansion around classical solutions characterized by temporal windings. This semiclassical approximation reveals a hadronic energy density of states of a Hagedorn type, with the coefficient determined by the gauge theory string tension as expected for confining theories. We argue that our proposal captures primarily information about states of pure N=1 SYM theory, given that this semiclassical approximation does not entail a projection onto states of large U(1) charge.

Journal Article↗

PubMed2005

Connecting black holes and black strings.

Static vacuum spacetimes with one compact dimension include black holes with localized horizons but also uniform and nonuniform black strings where the horizon wraps over the compact dimension. We present new numerical solutions for these localized black holes in 5 and 6 dimensions. Combined with previous 6D nonuniform string results, these provide evidence that the black hole and nonuniform string branches join at a topology changing solution.

Journal Article↗