1,355,726 research outputs found
Do you cov me? Effect of coverage reduction on metagenome shotgun sequencing studies
No full textShotgun metagenomics sequencing is a powerful tool for the characterization of complex biological matrices, enabling analysis of prokaryotic and eukaryotic organisms and viruses in a single experiment, with the possibility of reconstructing de novo the whole metagenome or a set of genes of interest. One of the main factors limiting the use of shotgun metagenomics on wide scale projects is the high cost associated with the approach. We set out to determine if it is possible to use shallow shotgun metagenomics to characterize complex biological matrices while reducing costs. We used a staggered mock community to estimate the optimal threshold for species detection. We measured the variation of several summary statistics simulating a decrease in sequencing depth by randomly subsampling a number of reads. The main statistics that were compared are diversity estimates, species abundance, and ability of reconstructing de novo the metagenome in terms of length and completeness. Our results show that diversity indices of complex prokaryotic, eukaryotic and viral communities can be accurately estimated with 500,000 reads or less, although particularly complex samples may require 1,000,000 reads. On the contrary, any task involving the reconstruction of the metagenome performed poorly, even with the largest simulated subsample (1,000,000 reads). The length of the reconstructed assembly was smaller than the length obtained with the full dataset, and the proportion of conserved genes that were identified in the meta-genome was drastically reduced compared to the full sample. Shallow shotgun metagenomics can be a useful tool to describe the structure of complex matrices, but it is not adequate to reconstruct-even partially-the metagenome
Repair potential of a laboratory-processed nano-hybrid resin composite
No full textThe purpose of this study was to compare the 24-h composite-to-composite microtensile bond strength of Gradia Forte (GF) repaired with the same or a different material after different surface treatments. Different groups were set up, in which composite blocks of GF were subjected to the following treatments: Group 1, sandblasting with 50-microm aluminum oxide and 37% phosphoric acid etching (PA); Group 2, bur roughening and etching with 37% PA; Group 3, etching with 37% PA only. In all groups, a bonding resin was used as an intermediate agent prior to layering of the repair material (Gradia Direct (GD), Gradia (G), or GF). Bond strengths were then determined and analysed statistically. Scanning electron microscopy (SEM) evaluation of substrates and bonded interfaces was also performed. Surface treatment (P < 0.001) and repair materials (P < 0.001) were factors that significantly affected repair strength, whereas their interaction (P = 0.31) had no significant effect. Group 3 showed significantly superior repair strength to Groups 1 and 2, whereas Group 2 showed significantly weaker repair strength to Groups 1 and 3. Irrespective of surface treatment, GD and G gave similar results, which were better than those obtained using GF. The lowest probability of failure was found for GD and G in Group 3, whereas the highest was found for GF in Groups 1 and 2. Premature failures occurred mainly with G and GF. No pre-testing failures were found in the sandblasting/GD subgroup. Surface-treated composites showed different textures under SEM, whereas composite-repair bonds showed comparable interfacial feature
Insights on the Excitation Spectrum of Graphene Contacted with a Pt Skin
No full textThe excitation spectrum in the region of the intraband (Dirac plasmon) and interband (π plasmon) plasmons in graphene/Pt-skin terminated Pt3Ni(111) is reproduced by using an ab-initio method and an empirical model. The results of both methods are compared with experimental data. We discover that metallic screening by the Pt layer converts the square-root dispersion of the Dirac plasmon into a linear acoustic-like plasmon dispersion. In the long-wavelength limit, the Pt d electron excitations completely quench the π plasmon in graphene at about 4.1 eV, that is replaced by a broad peak at about 6 eV. Owing to a rather large graphene/Pt-skin separation (≈3.3 Å), the graphene/Pt-skin hybridization becomes weak at larger wave vectors, so that the π plasmon is recovered with a dispersion as in a free-standing graphene
Comparison of Mechanical Properties in Compacted and Spheroidal Graphite Irons
No full textMechanical properties of cast irons are governed by the size, distribution and shape of the incorporated graphite particles. In a set of experiments, two groups of cast alloys, Compacted Graphite Iron (CGI) and Spheroidal Graphite Iron (SGI) were investigated. Even if the processes used for their production could be apparently considered quite similar, these two materials are characterized by a net difference in graphite particles and, as consequence, in final properties. Adding, while SGI benefits of a wide scientific literature supporting its large use, CGI is a relatively unexplored
Do you cov me? Effect of coverage reduction on metagenome shotgun sequencing studies [version 4; peer review: 2 approved with reservations, 2 not approved]
No full textShotgun metagenomics sequencing is a powerful tool for the characterization of complex biological matrices, enabling analysis of prokaryotic and eukaryotic organisms and viruses in a single experiment, with the possibility of reconstructing de novo the whole metagenome or a set of genes of interest. One of the main factors limiting the use of shotgun metagenomics on wide scale projects is the high cost associated with the approach. We set out to determine if it is possible to use shallow shotgun metagenomics to characterize complex biological matrices while reducing costs. We used a staggered mock community to estimate the optimal threshold for species detection. We measured the variation of several summary statistics simulating a decrease in sequencing depth by randomly subsampling a number of reads. The main statistics that were compared are diversity estimates, species abundance, and ability of reconstructing de novo the metagenome in terms of length and completeness. Our results show that diversity indices of complex prokaryotic, eukaryotic and viral communities can be accurately estimated with 500,000 reads or less, although particularly complex samples may require 1,000,000 reads. On the contrary, any task involving the reconstruction of the metagenome performed poorly, even with the largest simulated subsample (1,000,000 reads). The length of the reconstructed assembly was smaller than the length obtained with the full dataset, and the proportion of conserved genes that were identified in the meta-genome was drastically reduced compared to the full sample. Shallow shotgun metagenomics can be a useful tool to describe the structure of complex matrices, but it is not adequate to reconstruct—even partially—the metagenome
Leading Women Entrepreneurs of Thailand
No full text"Marriage is like an elephant-- the husband is the front legs that choose the direction, the wife the back legs, providing the power!" – Thai Legend\ud
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Introduction\ud
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The Thai legend above illustrates the important yet veiled role of women in Thai society. Women comprise 46% of the labour force, 26% of senior officials, legislators and managers (UNDP, 2006), and nearly 50% of the entrepreneurs (Minniti, Allen & Langowitz, 2006) in Thailand. Most of these women are running small companies, but a handful head large, growth-oriented entrepreneurial firms. In this chapter, we profile four leading Thai women who have been recognized with the highly prestigious "Leading Women Entrepreneurs of the World" (LWEW) award: Kobkarn Wattanavranangkul , Khungying Pornthip Narongdej, Supapan Pichaironarongsongkram and Supaluck Umpujh.\ud
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Despite the awareness of female entrepreneurs’ role in economic development (OECD, 2000), there has been limited academic attention (Baker, Aldrich & Liou 1997; de Bruin, Brush & Welter 2006), particularly to highly successful "gazelle" entrepreneurs. Extant female entrepreneurship research has explored a range of topics including gender differences (e.g. Birley, 1989; Hisrish & Brush, 1984), performance (e.g. Fasci & Valdez, 1998) and financing (e.g. O’Gorman & Terjesen, 2005). Researchers have called for studies of entrepreneurship that take into account the role of culture (Hayton, George & Zahra, 2002) and are of a qualitative nature (Gartner & Birley, 2002; Davidsson, 2004).\ud
This chapter proceeds as follows. We begin by providing an overview of enterprise and female entrepreneurship in Thailand. Next, we describe relational theory in the context of female entrepreneurship, paying particular attention to the role of family. Following a description of the data and methodology, we review four case studies of Thai "gazelle" entrepreneurs. Following a discussion of key themes, we conclude with implications and suggestions for future research
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe 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
Multiband Optical Networks Control and Provisioning
No full textThis paper presents viable solutions for the control of a multi-band optical network. NETCONF and augmented OpenConfig YANG data models are adopted to configure and monitor the state of network devices. Both connection provisioning and Quality of transmission estimation account for Stimulated Raman Scattering
Experimental Optimization of Spectrum-Efficient Super-Channels in Elastic Optical Networks
No full textAutomatic super-channel optimization is experimentally demonstrated using a 600Gb/ s transponder in the SDN-controlled Elastic Optical Network. Margin reduction while guaranteeing Quality of Transmission allows for a spectrum occupation reduction of 25%
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