Identical Strings Research Articles

Exact controllability of a system of coupled strings in parallel

We consider a system of parallel identical strings coupled by distributed springs and dampers. It is shown that despite the distributed damping, there exists a branch of eigenvalues that is purely imaginary leading to sustained oscillations. It is also proved that when Dirichlet boundary controls are applied and the control time is greater than or equal to , where c is the wave speed, the system is exactly controllable in an appropriate state space.

Helical self-assembly of molecules in pseudopolymorphs of racemic 2,6-di-O-(4-halobenzoyl)-myo-inositol 1,3,5-orthoformates: clues for the construction of molecular assemblies for intermolecular acyl transfer reaction

The crystal structure of racemic 2,6-di-O-benzoyl-myo-inositol 1,3,5-orthoformate (1) which underwent a facile intermolecular benzoyl transfer reaction in the solid state, revealed a helical assembly of molecules along the two-fold screw axis via O–H⋯O hydrogen bond bringing the electrophile (CO) and the nucleophile (–OH) in close proximity along the helical axis. However, structurally related racemic 2,6-di-O-(p-halobenzoyl)-myo-inositol 1,3,5-orthoformates (bromo (2) and chloro (3)) produced triclinic dimorphs (both P) when crystallized from methanol and ethyl acetate. Molecules in either form did not assemble spirally (like 1), and instead exhibited a one-dimensional isostructurality, bridging O–H⋯O linked identical molecular strings via C–H⋯O interactions across the inversion center. However, the molecules of 2 and 3 assembled in a helical manner similar to 1 with inclusion of solvent molecules in the crystal lattice when crystallized from other common organic solvents. Remarkably, in all the solvates the host molecules formed strikingly similar helices around the crystallographic 21-screw axis through O–H⋯O bond involving the –OH group and carbonyl oxygen of the equatorial C2-O-benzoyl group. Comparison of the crystal structure of dimorphs and the solvatomorphs revealed that the solvent molecules, which interact with the orthoformate-bridge, trigger the helix formation of the host. The difference in the crystal structures of solvatomorphs arises in the interlinking of the neighbouring helices, which creates voids of different sizes to accommodate the solvent molecules. All the solvates crystallized in the monoclinic system distributed over three different space groups P21/n, P21/c and C2/c. In the P21/n system, the adjacent helices are linked via C–X⋯O contacts, in P21/c via C–H⋯X (X = Cl, Br) contacts and in C2/c via short X⋯X contacts (X = Cl). The helical organization achieved through solvent mediation and inclusion is of significance in creating molecular packing for intermolecular acyl transfer reactions in crystals.

T-REKS: identification of Tandem REpeats in sequences with a K-meanS based algorithm

Over the last years a number of evidences have been accumulated about high incidence of tandem repeats in proteins carrying fundamental biological functions and being related to a number of human diseases. At the same time, frequently, protein repeats are strongly degenerated during evolution and, therefore, cannot be easily identified. To solve this problem, several computer programs which were based on different algorithms have been developed. Nevertheless, our tests showed that there is still room for improvement of methods for accurate and rapid detection of tandem repeats in proteins. We developed a new program called T-REKS for ab initio identification of the tandem repeats. It is based on clustering of lengths between identical short strings by using a K-means algorithm. Benchmark of the existing programs and T-REKS on several sequence datasets is presented. Our program being linked to the Protein Repeat DataBase opens the way for large-scale analysis of protein tandem repeats. T-REKS can also be applied to the nucleotide sequences. The algorithm has been implemented in JAVA, the program is available upon request at http://bioinfo.montp.cnrs.fr/?r=t-reks. Protein Repeat DataBase generated by using T-REKS is accessible at http://bioinfo.montp.cnrs.fr/?r=repeatDB.

Retention of the structure underlying sentences

The present study investigated memory retention of the structural aspects of sentences. Participants studied five sets of eight syntactically identical but nonsensical strings of words (e.g., ‘BEAUTIFUL TRANSPORTATION SHEDS TEMPORARY PLANTS’ and ‘HARSH CLOTHING REQUIRES PORTABLE PENS’). Participants were subsequently presented with a recognition test containing studied strings, non-studied strings that adhered to the same syntactical structure as a studied set of strings (critical lures), and non-studied strings that adhered to a non-studied syntactical structure (new lures). Participants’ recognition confidence ratings were higher for critical than for new lures, but only when the word strings used in the experiment adhered to a legal grammatical structure (e.g., ‘BEAUTIFUL TRANSPORTATION SHEDS TEMPORARY PLANTS’). No such confidence ratings effect was found between critical and new lures that corresponded to ungrammatical sets (e.g., ‘SOUR A KICK CLEAN BALLOON HARD’ and ‘FLIMSY AT THROW HANG TREE CHEAP’).

Age-related differences in the areas of Broca and Wernicke using functional magnetic resonance imaging

Previous studies have identified differences in the brain activation pattern between children and adults as well as between healthy subjects and patients using various imaging methods. Despite the increase of old people in the population, at present no study has applied a language task to investigate differences in adults. We used a simple paradigm to elicit activation in young and old adults to investigate differences in the activation of the classical Broca and Wernicke areas. Using functional magnetic resonance imaging, we applied a simple language paradigm to 10 right-handed subjects in each age group. Words and letter strings were presented separately with the instruction to decide for each pair if it represents a synonym (in case of words) or identical strings (in case of letters). The corresponding changes in the brain activation for words and letters were contrasted for each individual subject and compared by statistical parametric methods. For all subjects, the paradigm resulted in the activation of Broca and Wernicke areas in the left hemisphere only. Group analysis demonstrated a higher level of activation in Broca as well as in Wernicke areas for the young adults in comparison with the old adults. The applied, short paradigm provided consistent activation of the classical Broca and Wernicke areas in both age groups. These results demonstrate specific age-related differences in the processing of language stimuli during identical performance measures.

Re-Using Text from One's Own Previously Published Papers: An Exploratory Study of Potential Self-Plagiarism

A preliminary, two-part study explored the extent to which authors reuse portions of their own text from previously published papers. All 9 articles from a recent issue of a psychology journal were selected as target papers. Up to 3 of the most recent references cited in each of the target articles and written by the same authors were also obtained. All target articles and their corresponding references were stored digitally. Then, using specialized software, each reference was compared to its target article to assess the number of strings of text identical to both papers. Only one of the nine target articles reused significant amounts of text from one of its references. To explore further the possibility of additional text reuse, the references in each of the 9 sets of papers were compared against each other. The new comparison identified 5 pairs of papers with a substantial number of identical strings of text of 6 consecutive words in length or longer, but most of the reused text was confined to the Method section. The results suggest that some of these authors reuse their own text with some frequency, but this was largely confined to complex methodological descriptions of a research design and procedure.

DNA polymorphism detector: an automated tool that searches for allelic matches in public databases for discrepancies found in clone or cDNA sequences

DNA polymorphism detector (DPD) is a new web application developed to help automate the process of cDNA clone validation. DPD identifies and highlights discrepancies between any cDNA clone sequence and its expected reference sequence. To determine if these differences correspond to natural genetic polymorphisms (versus artifacts introduced during clone production or evaluation), DPD uses the discrepancies, along with flanking sequences, to search GenBank for identical matching strings. If matching DNA sequences are found, DPD verifies that they are from the same gene. The application then reports the discrepancy as a polymorphism along with the corresponding GenBank reference information. DPD is currently hosted by the Harvard Institute of Proteomics at http://www.hip.harvard.edu

Analytic study of nonperturbative solutions in open string field theory

We propose an analytic framework to study the nonperturbative solutions of Witten's open string field theory. The method is based on the Moyal star formulation where the kinetic term can be split into two parts. The first one describes the spectrum of two identical half strings which are independent from each other. The second one, which we call midpoint correction, shifts the half string spectrum to that of the standard open string. We show that the nonlinear equation of motion of string field theory is exactly solvable at zeroth order in the midpoint correction. An infinite number of solutions are classified in terms of projection operators. Among them, there exists only one stable solution which is identical to the standard butterfly state. We include the effect of the midpoint correction around each exact zeroth order solution as a perturbation expansion which can be formally summed to the complete exact solution.

Some properties of the basis finite automaton

The present paper discusses non-deterministic finite Rabin-Scott's automata. The majority of works recently dealing with this subject were, in fact, concerned only with properties of a canonical form automata or of some objects equivalent to it. This article continues the series of works in which the authors state a different point of view, describing the finite automata as just another invariant of the given regular language called basis finite automaton. In this article the authors argue on some new properties for the basis finite automaton. One of them is included into basis automaton's table of binary relations. It is stated that this table can not contain either identical strings or identical columns. Another property depicts a possibility to obtain any finite automaton for a given regular language by the process of duplicating or combining some of its states.

Note on size variation of body and statoliths in the oval squid Sepioteuthis lessoniana hatchlings

Oval squid Sepioteuthis lessoniana hatchlings originated from maternally identical egg strings were incubated under constant temperature and examined with special reference to statolith formation. Statoliths of a hatchling already had an adult-like shape, and some increments were observed. In spite of the maternally identical origin and constant incubation temperature (25°C), dorsal mantle length and statolith length of the hatchlings varied from 4.70 to 6.26 mm and 320 to 410 μm, respectively (N=14). These variations had a positive correlation with the embryonic duration ranging from 22 to 27 d, which means that the size of body and statolith becomes larger in hatchlings hatching later.

Three interacting strings in two dimensions: non-universal and multiple unbinding transitions

Three non-intersecting strings in two dimensions which interact via short-ranged attractive potentials are studied using bath transfer matrix methods and Monte Carlo tech- niques. The critical behavior at the unbinding transition and the critical values of the potential strength are determined for symmetric and asymmetric bundles of strings. In the asymmetric case, for which the two outer strings have diiferent hne tensions (or interact via dilferent po- tentials), the strings unbind in two subsequent transitions, which then exhibit universal critical behavior. In the symmetric case, where the two outer strings have the same line tension, trie three strings unbind simultaneously. The critical behavior at this unbinding transition is found to be non-universal for the whole range of accessible length scales, but its parameter dependence is found to be in strong disagreement with trie predictions of trie so-called necklace model. Trie more flexible the inner string, the deeper the critical potential. However, within the numerical error, three identical strings are found to unbind at the same critical potential strength as two strings with the same line tensions.

STATISTICS OF LINKED STRINGS

We discuss the possibilities for statistics of identical strings when they are linked. We show that while there are possibilities for novel statistics and for a violation of the spin-statistics relation, the results we get are different from the ones for unlinked strings.

Infrequent words are longer in duration than frequent words.

Studies measuring productions of frequent and infrequent words have shown an increased duration for the infrequent items. However, this increase has previously been attributed to anything but word frequency: differences in the number of phonemes, in the duration of the phonemes themselves, in the number of letters in the spelling, in functional load, and even in the pauses between the items. The present study attempted to avoid those interpretations by using high-frequency/low-frequency homophones that are not also homographs (e.g., ‘‘through’’/‘‘threw’’). In this way, the number and type of phonemes were exactly controlled for. In addition, the items were chosen so that the lower frequency word had the same number of letters or fewer, and did not have an exceptional spelling unless the higher frequency word did as well. These items were then produced in a rehearsed, speeded list, where functional load was negligible. Even so, the infrequent items were longer in duration (by about 3% in preliminary measurements). Since identical phonemes strings were uttered, these results suggest that a link to the lexicon is maintained throughout production. [Work supported by NIH Grant DC-00825.]

NOVEL STATISTICS FOR STRINGS AND STRING “CHERN-SIMON” TERMS

We study the statistics of identical strings in R3. Novel possibilities for string statistics are shown to exist at least in the absence of physical inputs such as the possibility of string pair creation. There are for instance strings which do not obey Bose, Fermi or parastatistics. There are also strings which violate the standard spin-statistics relation. The Abelian Chern-Simons Lagrangian which leads to anyons is generalized to strings. It leads to exotic phase changes of wave functions when strings are moved in homotopically nontrivial loops in the N-string configuration space. Non-Abelian generalizations of this Abelian string Lagrangian are also proposed.

Comparison requirements and attention in identical-nonidentical stimulus discriminations.

Perceptual matching data show several puzzling effects. Particularly problematic are the disparities between the processing rates for same and different stimuli--the fast-same effect--and between the processing rates for two same-different judgment tasks that are related as mirror images--the task effect. Current models have difficulty accounting simultaneously for both effects. Central to these models is a stimulus comparison process that derives relative judgments of sameness and difference from tests of the congruence of stimulus representations. A contrasting view holds that same-different judgments can be modeled as absolute, rather than relative, judgments. This latter view is shown to be supported by experimental data. Reaction times for judgments of identical letter strings increase with string length at the same rate whether judgments are based on all the information in the strings or just the information in a single pair of component letters. The data show that stimulus comparisons of the sort described by previous models are not involved in these judgments. An attentional model accounts for the data and for the fast-same and task effects as well.

Crystal structures of some niobium and tantalum oxides: IX. K 3Nb 7O 19: A new potassium niobium oxide tunnel structure

K 3Nb 7O 19 crystallizes in the triclinic system with unit cell dimensions (from single-crystal data) a = 14.143(3), b = 9.948(2), c = 6.463(2)Å, α = 106.45(2), β = 95.82(1), γ = 97.29(1)°, and space group P 1, z = 2 . The structure was solved using the Patterson (“P1” method) and Fourier techniques. Of the 4974 unique reflections measured by counter techniques 2722 with I ≥ 3 σ( I) were used in the least-squares refinement of the model to a conventional R of 0.049 ( R w 0.054). The structure of K 3Nb 7O 19 may be described as consisting of edge-shared pairs of octahedra that are corner shared to one another to form double strings seven pairs long. Each of these strings is corner shared to four other identical strings forming tunnels bounded by six octahedra. Two pairs of octahedra at each end of the strings of seven pairs are edge shared to adjacent strings forming a second series of tunnels approximately perpendicular to the first series. Potassium ions are located within both series of tunnels. The structure may also be described as one in which the oxygen ions are in approximately cubic close-packed layers perpendicular to [501] with potassium ions occupying anion sites in a regular manner.

Using a Computer in the Production of German Teaching Materials

I am currently investigating the potential of computers and word processors in the production of teaching materials for courses in German language, linguistics, and literature. I see such an investigation as distinct from Computer Assisted Learning in the strict sense, as it involves interaction between the computer and the teacher rather than with the student. The project is based on the premise that authentic discourse-be it spoken or written, fictional or nonfictional-is a rich and valuable resource for the study of a foreign language. Yet there are few foreign language teaching materials which draw on such texts in a systematic way. By the same token, the various editions of difficult foreign language texts, such as works of literature or texts of a technical nature, tend to give explanations and comments on a more or less ad hoc basis. In preparing the materials I draw mainly on programs which present identical strings in context while keeping count of them simultaneously. The results of such analyses can serve many uses, e.g.:

The active use of grammar in speech perception

Judgments of the location of short bursts of noise in sentences were used to reveal perceptual segmentation of sentences. It was assumed that segmentation would correspond to major constituent boundaries. In order to control for correlated variables of pitch and intonation, identical acoustic material was provided with alternate constituent structures. It was found that differences in response to identical strings were predicted by the points of variation in constituent structure.