182,809 research outputs found
The Cobalt(II) Oxidotellurate(IV) Hydroxides Co₂(TeO₃)(OH)₂ and Co₁₅(TeO₃)₁₄(OH)₂
No full textPreviously unknown Co₂(TeO₃)(OH)₂ and Co₁₅(TeO₃)₁₄(OH)₂ were obtained under mild hydrothermal reaction conditions (210 °C, autogenous pressure) from alkaline solutions. Their crystal structures were determined from single-crystal X-ray diffraction data. Co₂(TeO₃)(OH)₂ (Z = 2, P (Formula presented.), a = 5.8898(5), b = 5.9508(5), c = 6.8168(5) Å, α = 101.539(2), β = 100.036(2), γ = 104.347(2)°, 2120 independent reflections, 79 parameters, R[F² > 2σ(F²)] = 0.017) crystallizes in a unique structure comprised of undulating ²∝[Co₂(OH)₆/₃O₃/₃O₂/₂O₁/₁]⁴⁻ layers. Adjacent layers are linked by TeIV atoms along the [001] stacking direction. Co₂(TeO₃)(OH)₂ is stable up to 450 °C and decomposes under the release of water into Co₆Te₅O₁₆ and CoO. Magnetic measurements of Co₂(TeO₃)(OH)₂ showed antiferromagnetic ordering at ≈ 70 K. The crystal structure of Co₁₅(TeO₃)₁₄(OH)₂ (Z = 3, R (Formula presented.), a = 11.6453(2), c = 27.3540(5) Å, 3476 independent reflections, 112 parameters, R[F² > 2σ(F²)] = 0.026) is isotypic with Co₁₅(TeO₃)₁₄F₂. A quantitative structural comparison revealed that the main structural difference between the two phases is connected with the replacement of F by OH, whereas the remaining part of the three-periodic network defined by [CoO₆], [CoO₅(OH)], [CoO₅] and [TeO₃] polyhedra is nearly unaffected. Consequently, the magnetic properties of the two phases are similar, namely being antiferromagnetic at low temperatures
Nonlinear formulations and improved randomized approximation algorithms for multiway and multicut problems
No full textCover title.Includes bibliographical references (p. 21-22).D. Bertsimas, C. Teo and R. Vohra
Appropriate Similarity Measures for Author Cocitation Analysis
No full textWe 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
Left atrial myxoma: magnet or echo?
No full textThe definitive version is available at www.blackwell-synergy.comK. C. Roberts-Thomson, K. S. L. Teo, R. Stuklis and S. G. Worthle
"Closing the R&D Gap, Evaluating the Sources of R&D Spending"
No full textBoth spending and tax policies have been implemented in the United States with the goal of stimulating private sector research and development (R&D). Karier questions whether current R&D policy, especially the research and experimentation tax credit, can contribute to closing the gap between nondefense expenditures on R&D in the United States and such expenditures in other countries, such as Japan and Germany. He also explores possible changes to our current R&D policy to make it more effective.
2′-Deoxy-2′-fluoro-arabinonucleic acid: a valid alternative to DNA for biotechnological applications using charge transport
No full textThe non-biological 2′-deoxy-2′-fluoro-arabinonucleic acid (2′F-ANA) may be used as a valid alternative to DNA in biomedical and electronic applications because of its higher resistance to hydrolysis and nuclease degradation. However, the advantage of using 2′F-ANA in such applications also depends on its charge-transfer properties compared to DNA. In this study, we compare the charge conduction properties of model 2′F-ANA and DNA double-strands, using structural snapshots from MD simulations to calculate the electronic couplings and reorganization energies associated with the hole transfer steps between adjacent nucleobase pairs. Inserting these charge-transfer parameters into a kinetic model for charge conduction, we find similar conductive properties for DNA and 2′F-ANA. Moreover, we find that 2′F-ANA's enhanced chemical stability does not correspond to a reduction in the nucleobase π-stack structural flexibility relevant to both electronic couplings and reorganization free energies. Our results promote the use of 2′F-ANA in applications that can be based on charge transport, such as biosensing and chip technology, where its chemical stability and conductivity can advantageously combine
Impaired filtering of distracter stimuli by TE neurons following V4 and TEO lesions in macaques
No full textDirecting attention to a behaviorally relevant visual stimulus can overcome the distracting effects of other nearby stimuli. Correspondingly, physiological studies indicate that attention serves to filter distracting stimuli from receptive fields (RFs) in several extrastriate areas. Moreover, a recent study demonstrated that lesions of extrastriate areas V4 and TEO produce impairments in attentional filtering. A critical remaining question concerns why lesions of ventral stream areas cause attentional filtering impairments. To address this question, we tested the effects of restricted area V4 and TEO lesions on both behavioral performance and the responses of downstream neurons in area TE. The lesions impaired behavioral discrimination thresholds and altered neuronal selectivity for target stimuli in the presence of distracters. With attention to the target, but in the absence of V4 and/or TEO inputs, TE neurons responded as though attentional inputs could no longer be used to filter distracters from their RFs. This presumably occurred because top-down attentional signals were no longer able to filter distracters from the RFs of the cells that provide TE with major input. Consistent with this interpretation, increasing the spatial separation between targets and distracters, such that they no longer fell within a typical V4 RF dimension, restored both behavioral performance and neuronal selectivity in the portion of TE RFs affected by the V4 lesion
Reactivation of drug reaction with eosinophilia and systemic symptoms with ranitidine patch testing
No full textGoing 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
Psychometric properties of the italian version of the 25-Item hikikomori questionnaire for adolescents
No full textHikikomori is a form of social withdrawal that is commonly described as having an onset during adolescence, a life stage when other psychiatric problems can also emerge. This study aimed to adapt the 25-item Hikikomori Questionnaire (HQ-25) for the Italian adolescent population, examining its psychometric properties; associations between hikikomori and psychoticism, depression, anxiety, problematic internet use (PIU), psychotic-like experiences (PLEs), to confirm convergent validity of the HQ-25; and the interaction effect between symptoms of hikikomori and PIU in predicting PLEs. Two-hundred and twenty-one adolescents participated in the study. Measures included the HQ-25, the Psychoticism subscale of the Personality Inventory for the Diagnostic and Statistical Manual of Mental Disorders, the Depression and Anxiety subscales of the Brief Symptom Inventory, the Internet Disorder Scale, and the Brief Prodromal Questionnaire. Data showed a satisfactory fit for a three-factor model for the HQ-25 that is consistent with the original study on the HQ-25. Three factors (socialization, isolation, and emotional support) were associated with psychopathology measures. Six participants reported lifetime history of hikikomori. Symptoms of hikikomori and PIU did not interact in predicting PLEs. This is the first study to validate the HQ-25 in a population of adolescents. Findings provide initial evidence of the adequate psychometric properties of the Italian version of the HQ-25 for adolescents
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