369 research outputs found
Minimizing Acquisition Maximizing Inference -- A demonstration on print error detection
Is it possible to detect a feature in an image without ever looking at it?
Images are known to have sparser representation in Wavelets and other similar
transforms. Compressed Sensing is a technique which proposes simultaneous
acquisition and compression of any signal by taking very few random linear
measurements (M). The quality of reconstruction directly relates with M, which
should be above a certain threshold for a reliable recovery. Since these
measurements can non-adaptively reconstruct the signal to a faithful extent
using purely analytical methods like Basis Pursuit, Matching Pursuit, Iterative
thresholding, etc., we can be assured that these compressed samples contain
enough information about any relevant macro-level feature contained in the
(image) signal. Thus if we choose to deliberately acquire an even lower number
of measurements - in order to thwart the possibility of a comprehensible
reconstruction, but high enough to infer whether a relevant feature exists in
an image - we can achieve accurate image classification while preserving its
privacy. Through the print error detection problem, it is demonstrated that
such a novel system can be implemented in practise
Platinum–Vanadium Oxide Nanotube Hybrids
The present contribution reports on the features of platinum-based systems supported on vanadium oxide nanotubes. The synthesis of nanotubes was carried out using a commercial vanadium pentoxide via hydrothermal route. The nanostructured hybrid materials were prepared by wet impregnation using two different platinum precursors. The formation of platinum nanoparticles was evaluated by applying distinct reduction procedures. All nanostructured samples were essentially analysed by X-ray diffraction and transmission electron microscopy. After reduction, transmission electron microscopy also made it possible to estimate particle size distribution and mean diameter calculations. It could be seen that all reduction procedures did not affect the nanostructure of the supports and that the formation of metallic nanoparticles is quite efficient with an indistinct distribution along the nanotubes. Nevertheless, the reduction procedure determined the diameter, dispersion and shape of the metallic particles. It could be concluded that the use of H2PtCl6 is more suitable and that the use of hydrogen as reducing agent leads to a nanomaterial with unagglomerated round-shaped metallic particles with mean size of 6–7 nm
Risk perception among Brazilian individuals with high risk for colorectal cancer and colonoscopy
<p>Abstract</p> <p>Background</p> <p>Risk perception is considered a motivating factor for adopting preventive behaviors. This study aimed to verify the demographic characteristics and cancer family history that are predictors of risk perception and to verify if risk perception is a predictor of colonoscopy adherence.</p> <p>Methods</p> <p>Individuals with a family colorectal cancer history as indicated by a proband with cancer were interviewed by telephone. They responded to a questionnaire covering demographic characteristics, colonoscopy history and four questions on risk perception. Tests of multiple linear regression and logistic regression were used to identify associations between dependent and independent variables.</p> <p>Results</p> <p>The 117 participants belonged to 62 families and had a mean age of 45.2 years. The majority of these individuals were female (74.4%) and from families who met the Amsterdam Criteria (54.7%). The average risk perception was 47.6%, with a median of 50%. The average population perception of individual risk was 55.4%, with a median of 50%. Variables associated with a higher risk perception were age, gender, religion, school level, income, and death of a family member. The variable predicting colonoscopy was receiving medical information regarding risk (odds ratio OR 8.40).</p> <p>Conclusions</p> <p>We found that family cancer history characteristics (number of relatives with cancer, risk classification) are associated with adequate risk perception. Risk perception does not predict colonoscopy in this sample. The only variable that predicted colonoscopy was receiving medical information recommending screening.</p
TRY plant trait database - enhanced coverage and open access
Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives
MetaboHunter: an automatic approach for identification of metabolites from 1H-NMR spectra of complex mixtures
<p>Abstract</p> <p>Background</p> <p>One-dimensional <sup>1</sup>H-NMR spectroscopy is widely used for high-throughput characterization of metabolites in complex biological mixtures. However, the accurate identification of individual compounds is still a challenging task, particularly in spectral regions with higher peak densities. The need for automatic tools to facilitate and further improve the accuracy of such tasks, while using increasingly larger reference spectral libraries becomes a priority of current metabolomics research.</p> <p>Results</p> <p>We introduce a web server application, called MetaboHunter, which can be used for automatic assignment of <sup>1</sup>H-NMR spectra of metabolites. MetaboHunter provides methods for automatic metabolite identification based on spectra or peak lists with three different search methods and with possibility for peak drift in a user defined spectral range. The assignment is performed using as reference libraries manually curated data from two major publicly available databases of NMR metabolite standard measurements (HMDB and MMCD). Tests using a variety of synthetic and experimental spectra of single and multi metabolite mixtures show that MetaboHunter is able to identify, in average, more than 80% of detectable metabolites from spectra of synthetic mixtures and more than 50% from spectra corresponding to experimental mixtures. This work also suggests that better scoring functions improve by more than 30% the performance of MetaboHunter's metabolite identification methods.</p> <p>Conclusions</p> <p>MetaboHunter is a freely accessible, easy to use and user friendly <sup>1</sup>H-NMR-based web server application that provides efficient data input and pre-processing, flexible parameter settings, fast and automatic metabolite fingerprinting and results visualization via intuitive plotting and compound peak hit maps. Compared to other published and freely accessible metabolomics tools, MetaboHunter implements three efficient methods to search for metabolites in manually curated data from two reference libraries.</p> <p>Availability</p> <p><url>http://www.nrcbioinformatics.ca/metabohunter/</url></p
A study on the construct validity of the Parent-Child Conflict Tactics Scale (CTSPC) in an urban population in Northeast Brazil
The Parent-Child Conflict Tactics Scale (CTSPC) is one of the most widely used instruments in the world for investigating domestic violence against children, but targeted use has proven inadequate given the phenomenon's complexity. This study focused on the factor structure of CTSPC scales in an urban population in Northeast Brazil. We conducted a cross-sectional study in a cohort of 1,370 children in Salvador, Bahia State. Factor analysis with promax oblique rotation was performed, and the Kuder-Richardson coefficient was calculated. Factor analysis showed a different distribution of items in the factors as compared to the original instrument. Violence showed a gradual profile in each factor. The Kuder-Richardson coefficient was 0.63 for factor 1, 0.59 for factor 2, and 0.42 for factor 3. The items behaved differently from the original instrument, corroborating international studies. These findings support proposing a resizing of the CTSPC
Sparsity-based single-shot sub-wavelength coherent diffractive imaging
We present the experimental reconstruction of sub-wavelength features from
the far-field intensity of sparse optical objects: sparsity-based
sub-wavelength imaging combined with phase-retrieval. As examples, we
demonstrate the recovery of random and ordered arrangements of 100 nm features
with the resolution of 30 nm, with an illuminating wavelength of 532 nm. Our
algorithmic technique relies on minimizing the number of degrees of freedom; it
works in real-time, requires no scanning, and can be implemented in all
existing microscopes - optical and non-optical
Favouritism: exploring the 'uncontrolled' spaces of the leadership experience
In this paper, we argue that a focus on favouritism magnifies a central ethical ambiguity in leadership, both conceptually and in practice. The social process of favouritism can even go unnoticed, or misrecognised if it does not manifest in a form in which it can be either included or excluded from what is (collectively interpreted as) leadership. The leadership literature presents a tension between what is an embodied and relational account of the ethical, on the one hand, and a more dispassionate organisational ‘justice’ emphasis, on the other hand. We conducted 23 semi-structured interviews in eight consultancy companies, four multinationals and four internationals. There were ethical issues at play in the way interviewees thought about favouritism in leadership episodes. This emerged in the fact that they were concerned with visibility and conduct before engaging in favouritism. Our findings illustrate a bricolage of ethical justifications for favouritism, namely utilitarian, justice, and relational. Such findings suggest the ethical ambiguity that lies at the heart of leadership as a concept and a practice
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