1,720,981 research outputs found
Inference of gene regulatory networks and compound mode of action from time course gene expression profiles.
Full text linkMOTIVATION:
Time series expression experiments are an increasingly popular method for studying a wide range of biological systems. Here we developed an algorithm that can infer the local network of gene-gene interactions surrounding a gene of interest. This is achieved by a perturbation of the gene of interest and subsequently measuring the gene expression profiles at multiple time points. We applied this algorithm to computer simulated data and to experimental data on a nine gene network in Escherichia coli.
RESULTS:
In this paper we show that it is possible to recover the gene regulatory network from a time series data of gene expression following a perturbation to the cell. We show this both on simulated data and on a nine gene subnetwork part of the DNA-damage response pathway (SOS pathway) in the bacteria E. coli
Carbon dioxide in pollucite, a feldspathoid with ideal composition (Cs,Na)16Al16Si32O96 · nH2O
No full text""We report a single-crystal Fourier-transform infrared (FTIR) study of a sample of pollucite from. Maine, USA. Prior to our work, the sample had been characterized by single-crystal X-ray diffraction,. neutron diffraction and electron-probe microanalysis. It is cubic Ia3 ̄ d, with a crystal-chemical formula. Na1.93(Cs10.48Rb0.31K0.04)S=10.83(Al14.45Si33.97)S=48.42O96·3.92H2O, and an H2O content, determined. by thermogravimetric analysis, of 1.6 wt.%. The single-crystal FTIR spectrum has a doublet of intense. bands at 3670 and 3589 cm1, which are assigned to the n3 and n1 stretching modes of the H2O. molecule, respectively. A very intense and sharp peak at 1620 cm1 is assigned to the n2 bending. vibration. In the near-infrared region there is a relatively intense peak at 5270 cm1, which is assigned. to a combination (n2 + n3) mode of H2O, and a weak but well defined doublet at 7118 and 6831 cm1,. which is assigned to the first overtones of the fundamental stretching modes. A relatively weak but. extremely sharp peak at 2348 cm1 shows that the pollucite contains CO2 molecules in structural. cavities. Mapping the sample using FTIR indicates that both H2O and CO2 are homogeneously. distributed. Secondary ion mass spectrometry yielded an average CO2 content of 0.090.02 wt.%. On. the basis of this value, we determined the integrated molar absorption coefficient for the spectroscopic. analysis of CO2 in pollucite to be eiCO2. = 11,0003000 l mol1 cm2; the linear molar absorption. coefficient for the same integration range is elCO2. = 1600500 l mol1 cm1"
Single-crystal polarized ftir spectroscopy and neutron diffraction refinement of cancrinite
No full textWe relate here a combined single-crystal polarized-light FTIR (Fourier transform infrared) and neutron diffraction study of two natural cancrinites from Cameroun and Canada, respectively. Electron microprobe analyses show both samples to be almost end-member carbonate-cancrinites [ideal chemical formula Na6Ca2(Si6Al6O24)(CO3)2•2H2O].
The structural refinements show that the extra-framework content in the large 12-membered rings channels is represented by one independent Na-site (Na2) and two independent, and statistically distributed, CO3 groups. The geometry of the CO3 groups appears to be almost regular, with C1-OC1 ~ 1.298(7) Å and C2-OC2 ~ 1.300(5) Å, in agreement with the previous studies [1,2,3]. The atoms of the carbonate-groups are not perfectly coplanar, being z(C1) ≠ z(OC1) and z(C2) ≠ z(OC2). The H2O molecules and a further Na-site (Na1) lie in the cancrinite-cage; the H2O oxygen site (OW) lies off from the triad axis, giving rise to a statistical configuration with three equivalent and mutually exclusive water molecules, as already suggested by [1,2]. The high-quality neutron data show that the water molecule is almost symmetric, with very similar Ow-H1 and Ow-H2 bond-distances, and is slightly tilted from the (0001) plane. It is involved in bifurcated hydrogen bridges, with two possible bonds for H1 (i.e. OW-H1•••O2 and OW-H1•••O4) and two for H2 (i.e. OW-H2•••O3 and OW-H2•••O2). The Ow•••O donor-acceptor distances are all > 2.7 Å.
The polarised-light FTIR spectra show two main absorptions, at 3602 and 3531 cm-1, respectively. The former is polarised for E c, while the latter is polarized for E c. On the basis of the neutron diffraction data, the 3602 cm-1 band is assigned to the anti-symmetric stretching mode (ν3), while the 3531 cm-1 band is assigned to the symmetric stretching mode (ν1) of the same water molecule, in agreement with the presence of a single bending mode at 1630 cm-1. One additional weak component at 4108 cm-1 could possibly indicate the presence of low amounts of additional OH groups in the structure of cancrinite. Several overlapping bands in the 1300-1500 cm-1 range are strongly polarized for E c, and are assigned to the vibrations of the CO3 group.
References. [1] H.D. Grundy, I. Hassan, Can. Mineral., 20, 239-251, 1982; [2] P. Ballirano, A. Maras, Eur. J. Mineral., 16, 135-141, 2004; [3] I. Hassan, S.M. Antao, J.B. Parise, Am. Mineral., 91, 1117-1124, 2006
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
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