40,830 research outputs found
Les dits satiriques Des clers et Des vilains : de nouveaux aperçus sur leur transmission et édition
No full textBurrows Daron. Les Dits satiriques Des Clers et Des Vilains : de nouveaux aperçus sur leur transmission et édition. In: Romania, tome 125 n°497-498, 2007. pp. 118-131
Recursive procedures for measuring disorder in non-periodic sequences
No full textRecursive procedures are found for calculating the kth-order entropy of non-periodic sequences. These entropies are used as measures of disorder of the sequences and we treat: the Fibonacci sequence and generalizations; the Thue-Morse sequence together with generalizations and the period-doubling sequence. A discussion of the relative ordering of the Thue-Morse and the Fibonacci sequences is given and it is found too simplistic to use any one measure for comparison.PT: J; CR: BURROWS BL, 1991, J PHYS A-MATH GEN, V24, P3979 CHENG Z, 1988, PHYS REV B, V37, P4375 DALLESSANDRO G, 1990, PHYS REV LETT, V64, P1609 GUMBS G, 1989, J PHYS A-MATH GEN, V22, P951 GYORGYI G, 1985, PHYS REV A, V31, P3477 HARTLEY RVL, 1928, BELL SYST TECH J, V7, P535 KHINCHIN AI, 1957, MATH F INFORMATION T KLUIVING R, 1992, PHYSICA A, V183, P405 KLUIVING R, 1992, PHYSICA A, V183, P67 KLUIVING R, 1992, PHYSICA A, V183, P96 QIN MG, 1990, J PHYS-CONDENS MAT, V2, P1059 RIKLUND R, 1987, INT J MOD PHYS B, V1, P121 RYU CS, 1992, PHYS REV B, V46, P5162 RYU CS, 1993, PHYS REV B, V48, P132 SHANNON CE, 1948, BELL SYST TECH J, V27, P379 SHANNON CE, 1948, BELL SYST TECH J, V27, P623 SHANNON CE, 1949, MATH THEORY COMMUNIC WELSH D, 1988, CODES CRYPTOGRAPHY; NR: 18; TC: 6; J9: PHYSICA A; PG: 15; GA: RK763Source type: Electronic(1
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Identifying idiolect in forensic authorship attribution: an n-gram textbite approach
No full textForensic authorship attribution is concerned with identifying authors of disputed or anonymous documents, which are potentially evidential in legal cases, through the analysis of linguistic clues left behind by writers. The forensic linguist “approaches this problem of questioned authorship from the theoretical position that every native speaker has their own distinct and individual version of the language [. . . ], their own idiolect” (Coulthard, 2004: 31). However, given the diXculty in empirically substantiating a theory of idiolect, there is growing concern in the Veld that it remains too abstract to be of practical use (Kredens, 2002; Grant, 2010; Turell, 2010). Stylistic, corpus, and computational approaches to text, however, are able to identify repeated collocational patterns, or n-grams, two to six word chunks of language, similar to the popular notion of soundbites: small segments of no more than a few seconds of speech that journalists are able to recognise as having news value and which characterise the important moments of talk. The soundbite oUers an intriguing parallel for authorship attribution studies, with the following question arising: looking at any set of texts by any author, is it possible to identify ‘n-gram textbites’, small textual segments that characterise that author’s writing, providing DNA-like chunks of identifying material
Purple urchin burrows in bedrock, with and without occupants.
No full text<p>(A) A large tidepool outside the impact zone (site 4), with a dense population of live <i>Strongylocentrotus purpuratus</i> in November 2011. (B) Empty urchin burrows in a tidepool (site 16) after the mass mortality event. (C) Close-up of occupied purple urchin burrows, showing one urchin per burrow and 100% occupancy; note urchins are covered with debris. (D) Close-up of clean, empty urchin burrows such as those used to estimate pre-event densities.</p
On the Number of Equal-Letter Runs of the Bijective Burrows-Wheeler Transform
No full textThe Bijective Burrows-Wheeler Transform (BBWT) is a variant of the famous BWT [Burrows and Wheeler, 1994]. The BBWT was introduced by Gil and Scott in 2012, and is based on the extended BWT of Mantaci et al. [TCS 2007] and on the Lyndon factorization of the input string. In the original paper, the compression achieved with the BBWT was shown to be competitive with that of the BWT, and it has been gaining interest in recent years. In this work, we present the first study of the number of runs rB of the BBWT, which is a measure of its compression power. We exhibit an infinite family of strings on which rB of the string and of its reverse differ by a multiplicative factor of T(log n), where n is the length of the string.Peer reviewe
Organic carbon sequestration in earthworm burrows
No full textEarthworms strongly affect soil organic carbon cycling. The aim of this study was to determine whether deep burrowing anecic earthworms enhance carbon storage in soils and decrease C turnover. Earthworm burrow linings were separated into thin cylindrical sections with different distances from the burrow wall to determine gradients from the burrow wall to the surrounding soil. Organic C, total N, radiocarbon (C-14) concentration, stable isotope values (delta C-13, delta N-15) and extracellular enzyme activities were measured in these samples. Anecic earthworms increased C stocks by 270 and 310 g m(-2) accumulated in the vertical burrows. C-enrichment of the burrow linings was spatially highly variable within a distance of millimetres around the burrow walls. It was shown that C accumulation in burrows can be fast with C sequestration rates of about 22 g C m(-2) yr(-1) in the burrow linings, but accumulated C in the burrows may be mineralised fast with turnover times of only 3-5 years. Carbon stocks in earthworm burrows strongly depended on the earthworm activity which maintains continuous C input into the burrows. The enhanced extracellular enzyme activity of fresh casts was not persistent, but was 47% lower in inhabited burrows and 62% lower in abandoned burrows. Enzyme activities followed the C concentrations in the burrows and were not further suppressed due to earthworms. Radiocarbon concentrations and stable isotopes in the burrow linings showed an exponential gradient with the youngest and less degraded organic matter in the innermost part of the burrow wall. Carbon accumulation by anecic earthworm is restricted to distinct burrows with less influence to the surrounding soil. Contrary to the initial hypothesis, that organic C is stabilised due to earthworms, relaxation time experiments with nuclear magnetic resonance spectroscopy (NMR) did not reveal any enhanced adsorption of C on iron oxides with C stabilising effect. Our results suggest that earthworm activity does not substantially increase subsoil C stocks but burrows serve as fast ways for fresh C transport into deep soil horizons. (C) 2008 Elsevier Ltd. All rights reserved
A statistical analysis of circumstellar material in Type Ia supernovae
No full textA key tracer of the elusive progenitor systems of Type Ia supernovae (SNe Ia) is the detection of narrow blueshifted time-varying Na I D absorption lines, interpreted as evidence of circumstellar material surrounding the progenitor system. The origin of this material is controversial, but the simplest explanation is that it results from previous mass-loss in a system containing a white dwarf and a non-degenerate companion star. We present new single-epoch intermediate-resolution spectra of 17 low-redshift SNe Ia taken with XShooter on the European Southern Observatory Very Large Telescope. Combining this sample with events from the literature, we confirm an excess (∼20 per cent) of SNe Ia displaying blueshifted narrow Na I D absorption features compared to redshifted Na I D features. The host galaxies of SNe Ia displaying blueshifted absorption profiles are skewed towards later-type galaxies, compared to SNe Ia that show no Na I D absorption and SNe Ia displaying blueshifted narrow Na I D absorption features have broader light curves. The strength of the Na I D absorption is stronger in SNe Ia displaying blueshifted Na I D absorption features than those without blueshifted features, and the strength of the blueshifted Na I D is correlated with the B − V colour of the SN at maximum light. This strongly suggests the absorbing material is local to the SN. In the context of the progenitor systems of SNe Ia, we discuss the significance of these findings and other recent observational evidence on the nature of SN Ia progenitors. We present a summary that suggests that there are at least two distinct populations of normal, cosmologically useful SNe Ia
Synthetic Studies Toward Epidithiodiketopiperazine MPC1001 and 2-Pralidoxime Analogs. An Exploration in Birch Reduction, Oxidation, and N-Alkylation.
No full textThe first chapter presented in this dissertation describes the efforts toward the total synthesis of MPC1001. Three separate synthetic routes are discussed. Additionally, experiments with assorted additives led to a proposed radical degradation mechanism involving a biaryl triazene intermediate. A Birch reduction was uncovered during the synthetic studies that did not require liquid ammonia, allowing quick optimization to a mole-scale Birch alkylation. Then, oxidation conditions compatible with sterically-congested alcohols were found that granted studies into the following aldol condensations. Additionally, an intramolecular aza-Wacker reaction of an enamide was investigated. The second chapter describes an easy-to-use Birch reduction borne out of the total synthesis effort. After selecting a suitable internal standard, the reduction was optimized for both electron-poor and electron-rich systems. The substrate scope of the reduction was then investigated, with over 36 substrates being compatible. The structure-reactivity relationship with the amine ligand allowed a change in the selectivity from electron-poor arenes to electron-rich arenes. Also, the method was shown to be compatible with an organocuprate-mediated Michael addition with an electrophile that was previously incompatible with the Birch reduction. Finally, kinetic studies were completed that investigated the reduction mechanism, leading to the postulation of more active roles for both the solvent and the proton donor than previously suggested. The third chapter describes the synthesis of both bicyclic and sterically-congested reactivators of phosphylated acetylcholinesterase. Their synthesis necessitated a slight change in both the synthetic route and the purification protocol, allowing the reproducible and robust synthesis of analogs in the hypothesis-driven library. Although all analogs synthesized were not more potent than the already approved treatment, two analogs were shown to be more broadly active against assorted organophosphorus nerve agents than the approved treatment
Catches of tsetse from artificial warthog burrows.
No full text<p>Changes with time and daily maximum temperature in the numbers of pre-full-term-pregnancy (Pre-FT: A, C) and perinatal (B, D) female <i>G</i>. <i>pallidipes</i> captured per day in artificial warthog burrows at sites 1 to 5 at Rekomitjie Research Station. All data transformed to log<sub>e</sub>(<i>n</i>+1). Data shown for period 8 September to 7 November 1998: thereafter there were many zero catches.</p
Efficient Algorithm for Circular Burrows-Wheeler Transform
No full textGiven a set of d patterns, the circular dictionary matching problem is to index such that for any online query text T, we can quickly locate the occurrences of any cyclic shift of any pattern of within T efficiently. This problem can be applied on practical problems that arise in bioinformatics and computational geometry. Recently, Hon et al. (2011) applied a variant of the well-known Burrows-Wheeler transform, called circular Burrows-Wheeler transform (circular BWT) [Mantaci, Restivo, Rosone, and Sciortino, Theoretical Computer Science, 2007], and showed that this can be used to solve the circular dictionary matching problem efficiently. In this paper, we give the first construction algorithm for the circular BWT, which takes O(nlogn) time and requires O(nlogσ) bits working space, where n denotes the total length of the patterns in and σ is the alphabet size. © 2012 Springer-Verlag
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