91 research outputs found
A specific case in the classification of woods by FTIR and chemometric: discrimination of Fagales from Malpighiales
Fourier transform infrared (FTIR) spectroscopic data was used to classify wood samples from nine species within the Fagales and Malpighiales using a range of multivariate statistical methods. Taxonomic classification of the family Fagaceae and Betulaceae from Angiosperm Phylogenetic System Classification (APG II System) was successfully performed using supervised pattern recognition techniques. A methodology for wood sample discrimination was developed using both sapwood and heartwood samples. Ten and eight biomarkers emerged from the dataset to discriminate order and family, respectively. In the species studied FTIR in combination with multivariate analysis highlighted significant chemical differences in hemicelluloses, cellulose and guaiacyl (lignin) and shows promise as a suitable approach for wood sample classification
Applying the multi-threat framework of stereotype threat in the context of digital gaming.
Females often report experiencing stigmatisation pertaining to their competency in digital gaming communities. Employing the principles of the multi-Threat framework of stereotype threat, the current research examined the impact of gender-related stereotypes on females' gaming performance and related self-perceptions. In Experiment 1, 90 females were assigned to one of three conditions in which they were primed that their performance would be either diagnostic of their personal (self-As-Target) or gender group's ability (group-As-Target) or would be non-diagnostic of gaming ability (control). In Experiment 2, 90 females were primed that their performance would be judged by a group of other females (in-group source) or males (out-group source), or would be non-diagnostic of ability (control). Participants then completed a casual gaming task, as well as measures of competence beliefs, self-efficacy and self-esteem. Findings from Experiment 1 indicate that neither a self-As-Target nor a group-As-Target stereotype affected significantly gaming performance, or gamerelated self-efficacy, self-esteem and competency beliefs. Findings from Experiment 2 reveal further that females' gaming performance and associated self-perceptions were not impacted significantly by an in-group or out-group source of stereotype threat. The discussion turns to potential explanations for these findings, proposing that females may not perceive negative gender-gaming stereotypes to be an accurate representation of their personal or social group's gaming ability. We also discuss the implications of the experimental design and difficulty, as well as the potential for domain identification to moderate performance outcomes under stereotype threat
Application of chemometric analysis to infrared spectroscopy for the identification of wood origin
Chemical characteristics of wood are used in this study for plant taxonomy classification based on the current Angiosperm Phylogeny Group classification (APG III System) for the division, class and subclass of woody plants. Infrared spectra contain information about the molecular structure and intermolecular interactions among the components in wood but the understanding of this information requires multivariate techniques for the analysis of highly dense datasets. This article is written with the purposes of specifying the chemical differences among taxonomic groups, and predicting the taxa of unknown samples with a mathematical model. Principal component analysis, t-test, stepwise discriminant analysis and linear discriminant analysis, were some of the chosen multivariate techniques. A procedure to determine the division, class, subclass and order of unknown samples was built with promising implications for future applications of Fourier Transform Infrared spectroscopy in wood taxonomy classification
Proportions of CD4+ memory T cells are altered in individuals chronically infected with Schistosoma haematobium
Characterisation of protective helminth acquired immunity in humans or experimental models has focused on effector responses with little work conducted on memory responses. Here we show for the first time, that human helminth infection is associated with altered proportions of the CD4+ memory T cells, with an associated alteration of TH1 responses. The reduced CD4+ memory T cell proportions are associated with a significantly lower ratio of schistosome-specific IgE/IgG4 (marker for resistance to infection/re-infection) in uninfected older people. Helminth infection does not affect the CD8+ memory T cell pool. Furthermore, we show for the first time in a helminth infection that the CD4+ memory T cell proportions decline following curative anti-helminthic treatment despite increased CD4+ memory cell replication. Reduced accumulation of the CD4+ memory T cells in schistosome-infected people has implications for the development of natural or vaccine induced schistosome-specific protective immunity as well as for unrelated pathogens
Hypoxia-inducible factor-1α expression in the gastric carcinogenesis sequence and its prognostic role in gastric and gastro-oesophageal adenocarcinomas
Hypoxia-inducible factor-1 (HIF-1)α expression was studied in the gastric carcinogenesis sequence and as a prognostic factor in surgically resected gastric and gastro-oesophageal junction tumours. Protein expression was examined using immunohistochemistry on formalin-fixed biopsies of normal mucosa (n=20), Helicobacter pylori associated gastritis (n=24), intestinal metaplasia (n=24), dysplasia (n=12) and intestinal (n=19) and diffuse (n=21) adenocarcinoma. The relationship between HIF-1α expression and prognosis was assessed in resection specimens from 177 patients with gastric and gastro-oesophageal junction adenocarcinoma. Hypoxia-inducible factor-1α expression was not observed in normal gastric mucosa but increased in density (P<0.01) and intensity (P<0.01) with progression from H. pylori-associated gastritis, intestinal metaplasia, dysplasia to adenocarcinoma. The pattern of staining in the resection specimens was focally positive in 49 (28%) and at the invasive tumour edge in 41 (23%). Invasive edge expression was associated with lymph node metastases (P=0.034), advanced TNM stage (P=0.001) and was an adverse prognostic factor for cancer-specific survival (P=0.019). In univariate analysis and in comparison with tumours not expressing HIF-1α, invasive edge staining was associated with a hazard ratio of 1.6 (95% CI 1.0−2.5) and focally positive staining a hazard ratio of 0.7 (95% CI 0.5−1.2). Hypoxia-inducible factor-1α lost prognostic significance in multivariate analysis. The results suggest HIF-1α is involved in gastric carcinogenesis and disease progression, but is only a weak prognostic factor for survival
Energy allocation and behaviour in the growing broiler chicken
Broiler chickens are increasingly at the forefront of global meat production but the consequences of fast growth and selection for an increase in body mass on bird health are an ongoing concern for industry and consumers. To better understand the implications of selection we evaluated energetics and behaviour over the 6-week hatch-to-slaughter developmental period in a commercial broiler. The effect of posture on resting metabolic rate becomes increasingly significant as broilers grow, as standing became more energetically expensive than sitting. The proportion of overall metabolic rate accounted for by locomotor behaviour decreased over development, corresponding to declining activity levels, mean and peak walking speeds. These data are consistent with the inference that broilers allocate energy to activity within a constrained metabolic budget and that there is a reducing metabolic scope for exercise throughout their development. Comparison with similarly sized galliforms reveals that locomotion is relatively energetically expensive in broilers
Consumers’ value co-creation in sharing economy: The role of social support, consumers’ ethical perceptions and relationship quality
The ancient phenomenon of ‘sharing’ has become mainstream, and transformed the traditional consumer behavior due to proliferation of online sharing economy platforms. Millions of people participate in popular sharing economy platforms (SEPs) such as Airbnb and Uber. Although sharing economy research has gained interest, yet a holistic model that explains the formation of consumer value co-creation intentions on such platforms remains absent. The purpose of this study is to develop a model of the antecedents of consumers value co-creation intentions at SEPs and evaluate it empirically. Building on social support theory, relationship quality theory, value co-creation and marketing ethics literature, we propose a theoretical model that explains the formation of consumers’ value co-creation intentions. Empirical data was collected from 342 Generation Y consumers and analyzed using structural equation modeling (SEM). The results reveal that social support influences ethical perceptions, which further influences value co-creation. Ethical perceptions also influence consumers' trust, satisfaction and commitment with the SEP. However, trust and commitment do not influence value co-creation intentions. Our study contributes to the literature on sharing economy by providing a holistic model of the antecedents of consumers’ value co-creation intentions. We also detail theoretical and managerial implications
What Is Direct Allorecognition?
Direct allorecognition is the process by which
donor-derived major histocompatibility complex (MHC)-peptide
complexes, typically presented by donor-derived ‘passenger’
dendritic cells, are recognised directly by recipient T cells.
In this review, we discuss the two principle theories which
have been proposed to explain why individuals possess a
high-precursor frequency of T cells with direct allospecificity
and how self-restricted T cells recognise allogeneic MHCpeptide
complexes. These theories, both of which are supported
by functional and structural data, suggest that T cells
recognising allogeneic MHC-peptide complexes focus either
on the allopeptides bound to the allo-MHC molecules or the
allo-MHC molecules themselves. We discuss how direct
alloimmune responses may be sustained long term, the consequences
of this for graft outcome and highlight novel strategies
which are currently being investigated as a potential
means of reducing rejection mediated through this pathway
Molecular Assembly and Encapsulation Directed by Hydrogen-Bonding Preferences and the Filling of Space
Multiple copies of a molecule, held together in finite aggregates, give rise to properties and functions that are unique to their assembled states. Because these aggregates are held together by weak forces operating over short distances, a premium is placed on complementarity: The molecular surfaces must facilitate specific interactions that direct the assembly to one aggregate rather than another. Hydrogen-bonding preferences can be combined with molecular curvature to favor the assembly of four self-complementary subunits into a pseudo-spherical capsule. Filling the capsule with smaller, complementary molecules provides the final instruction for the assembly process.Peer reviewe
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