Beyond word frequency: Bursts, lulls, and scaling in the temporal distributions of words

Background: Zipf's discovery that word frequency distributions obey a power law established parallels between biological and physical processes, and language, laying the groundwork for a complex systems perspective on human communication. More recent research has also identified scaling regularities in the dynamics underlying the successive occurrences of events, suggesting the possibility of similar findings for language as well. Methodology/Principal Findings: By considering frequent words in USENET discussion groups and in disparate databases where the language has different levels of formality, here we show that the distributions of distances between successive occurrences of the same word display bursty deviations from a Poisson process and are well characterized by a stretched exponential (Weibull) scaling. The extent of this deviation depends strongly on semantic type -- a measure of the logicality of each word -- and less strongly on frequency. We develop a generative model of this behavior that fully determines the dynamics of word usage. Conclusions/Significance: Recurrence patterns of words are well described by a stretched exponential distribution of recurrence times, an empirical scaling that cannot be anticipated from Zipf's law. Because the use of words provides a uniquely precise and powerful lens on human thought and activity, our findings also have implications for other overt manifestations of collective human dynamics

Chitotriosidase, a chitinase, and the 39-kDa human cartilage glycoprotein, a chitin-binding lectin, are homologues of family 18 glycosyl hydrolases secreted by human macrophages

In various mammals, enzymatically active and inactive members of family 18 glycosyl hydrolases, containing chitinases, have been identified. In man, chitotriosidase is the functional chitinolytic enzyme, whilst the homologous human cartilage 39-kDa glycoprotein (HC gp-39) does not exhibit chitinase activity and its function is unknown. This study establishes that HC gp-39 is a chitin-specific lectin. It is experimentally demonstrated that a single amino acid substitution in the catalytic centre of the 39-kDa isoform of chitotriosidase, which generates a similar sequence to that in HC gp-39, results in a loss of hydrolytic activity and creates the capacity to bind to chitin. The possible implication of the finding for chitinolytic and chitin-binding proteins that are produced in high quantities by activated macrophages are discusse

Prosaposin deficiency - a rarely diagnosed, rapidly progressing, neonatal neurovisceral lipid storage disease. Report of a further patient

An infant presented with multifocal myoclonus and cyanotic hypoxemia immediately after birth, and severe feeding problems, a protein-losing enteropathy, massive ascites and grand-mal epilepsy marked his rapid downhill course, with death at 17 weeks. At 2 weeks, brain MRI revealed grey matter heterotopias in the parieto-occipital regions suggestive of a cortical morphogenetic disorder. In cultured skin fibroblasts, lipid storage and reduced activities of ceramidase, galactosylceramide beta-galactosidase and glucosylceramide beta-glucosidase were evident. Autopsy disclosed generalised lysosomal lipid storage with macrophages and adrenal cortex prominently affected. The pattern of stored lipids in cultured fibroblasts and in dewaxed spleen tissue blocks was compatible with a diagnosis of prosaposin (pSap) deficiency (pSap-d). Neuropathologically, there was a pronounced generalised neurolysosomal storage combined with a severe depletion of cortical neurons and extreme paucity of myelin and oligodendroglia. This pathology, in particular the massive neuronal loss, differed from that in other neurolipidoses and could be explained by the reduced hydrolysis of multiple sphingolipids and the loss of pSap's neurotrophic function. The absence of immunostainable saposins on tissue sections and the presence of a homozygous c.1 A > T mutation in the prosaposin gene confirmed the diagnosis. PSap-d may be an underdiagnosed condition in infants with severe neurological and dystrophic signs starting immediately after birth.Elleder, M; Jerábková, M; Befekadu, A; Hrebícek, M; Berná, L; Ledvinová, J; Hůlková, H; Rosewich, H; Schymik, N; Paton, BC. and Harzer, K.http://www.ncbi.nlm.nih.gov/pubmed/1594490

Sanfilippo Syndrome Type C: Mutation Spectrum in the Heparan Sulfate Acetyl-CoA: alpha-Glucosaminide N-Acetyltransferase (HGSNAT) Gene

Mucopolysaccharidosis (MPS) type IIIC or Sanfilippo syndrome type C is a rare autosomal recessive disorder caused by the deficiency of the lysosomal membrane enzyme, heparan sulfate acetyl-CoA (AcCoA): alpha-glucosaminide N,acetyltransferase (HGSNAT; EC 2.3.1.78), which catalyzes transmembrane acetylation. of the terminal glucosamine residues of heparan sulfate prior to their hydrolysis by alpha-N-acetylglucosaminidase. Lysosomal storage of undegraded heparan sulfate in the cells of affected patients leads to neuronal death, causing neurodegeneration and severely impaired development accompanied by mild visceral and skeletal abnormalities, including mild dwarfism, coarse facies, and joint stiffness. To date, 50 HGSNAT mutations have been identified in MPS IIIC patients: 40 were previously published and 10 novel mutations are reported here. The mutations span the entire structure of the gene and include 13 splice-site mutations, I I insertions and deletions, 8 nonsense mutations, and 18 missense mutations (http://chromium.liacs.nl/LOVD2/home.php? select_db = HGSNAT). In addition, four polymorphisms result in amino acid changes that do not affect activity of the enzyme. In this work we discuss the spectrum of MPS MC mutations, their clinical presentation and distribution within the patient population, and speculate how the mutations may affect the structure and function of HGSNAT. Hum Mutat 30, 918-925, 2009. (C) 2009 Wiley-Liss, Inc

Determination of economic indicators in the context of corporate sustainability performance

This article is focused on determination of the most significant economic indicators influencing corporate sustainability performance. Corporate sustainability performance is a multidimensional concept based on the original idea of sustainable development, replacing the traditional understanding of corporate performance only as capital appreciation for owners (shareholders). Compared to the original concept of sustainable development which consists of environmental, social and economic performance, the so-called triple-bottom-line, it is broaden to the responsibilities and the impact of Corporate Governance on the corporate performance. The basic set of economic indicators has been constructed from a synthesis of resources developed by international organizations (Global Reporting Initiative, International Federation of Accountants) and research among manufacturing companies in the Czech Republic. The basic set of twenty-five key indicators is divided into seven groups: Costs, Investments, Economic Results, Asset & financial resources utilization, Suppliers reliability, Penalties and R&D expenses. Basic set of indicators was presented to 23 top-managers who quantified the potential effect of each indicator to the success and sustainability of their companies. Through the methods of descriptive statistics knowledge of the particularities of each indicator was obtained. Correlation analysis and factor analysis were applied in order to eliminate information duplicity and dimensionality reduction. The result is a reduction in the number of economic indicators, so that the loss of information on the influence of the original indicators on the corporate sustainability is minimized. Corporate sustainability indicators are a tool for measuring and managing progress towards sustainability goals and environmental, social and economic impacts

Magnetized plasma implosion in a snail target driven by a moderateintensity laser pulse

Optical generation of compact magnetized plasma structures is studied in the moderate intensity domain. A sub-ns laser beam irradiated snail-shaped targets with the intensity of about 10(16) W/cm(2). With a neat optical diagnostics, a sub-megagauss magnetized plasmoid is traced inside the target. On the observed hydrodynamic time scale, the hot plasma formation achieves a theta-pinch-like density and magnetic field distribution, which implodes into the target interior. This simple and elegant plasma magnetization scheme in the moderate-intensity domain is of particular interest for fundamental astrophysical-related studies and for development of future technologies © The Author(s) 201