Search results for "Negativity"
showing 10 items of 301 documents
On the dark side of lifestyle blogging : the case of negative anonyms
2018
The social reciprocity between bloggers and their readers included in lifestyle blogs is inspired by casual exchange of information, opinions, and emotional support. Despite the obvious positive connotations, the world of lifestyle blogging also has a darker side to it. A negative anonym is recognized by bloggers as a reader who comments behind a pseudonym and distributes critical or abusive comments targeted against bloggers’ physical appearance, personality, life choices, or commercial collaborations. Bloggers are often regarded as influencers of social media. In this study, however, the perspective is reversed as I explore some of the ways bloggers are influenced by their readers. peerRe…
Non-negative matrix factorization Vs. FastICA on mismatch negativity of children
2009
In this presentation two event-related potentials, mismatch negativity (MMN) and P3a, are extracted from EEG by non-negative matrix factorization (NMF) simultaneously. Typically MMN recordings show a mixture of MMN, P3a, and responses to repeated standard stimuli. NMF may release the source independence assumption and data length limitations required by Fast independent component analysis (FastICA). Thus, in theory NMF could reach better separation of the responses. In the current experiment MMN was elicited by auditory duration deviations in 102 children. NMF was performed on the time-frequency representation of the raw data to estimate sources. Support to Absence Ratio (SAR) of the MMN co…
Relevance of the Electronegativity of Boron inη5-Coordinating Ligands: Regioselective Monoalkylation and Monoarylation in Cobaltabisdicarbollide[3,3′…
2003
Regioselective monoalkylation and monoarylation in cobaltabisdicarbollide clusters has been achieved starting from Cs[8-I-3,3'-Co(1,2-C 2 B 9 H 1 0 )(1',2'-C 2 B 9 H 1 1 )] by cross-coupling reactions between a B-I fragment andan appropriate Grignard reagent in the presence of a Pd catalyst and CuT. A considerable number of monoalkylated and monoarylated derivatives have been synthesized, which allowed study of the influence of boron in metallocene-type ligands and the effect of alkyl and aryl substituents on boron in boron anionic clusters. Experimental data from UV/ Vis spectroscopy, E 1 / 2 measurements, and X-ray diffraction analysis, and supported by EHMO and ab initio analyses, indica…
A nucleophilic gold complex.
2019
Solid-state auride salts featuring the negatively charged Au– ion are known to be stable in the presence of alkali metal counterions. While such electron-rich species might be expected to be nucleophilic (in the same manner as I–, for example), their instability in solution means that this has not been verified experimentally. Here we report a two-coordinate gold complex (NON)AlAuPtBu3 (where NON is the chelating tridentate ligand 4,5-bis(2,6-diisopropylanilido)-2,7-di-tert-butyl-9,9-dimethylxanthene) that features a strongly polarized bond, Auδ––Alδ+. This is synthesized by reaction of the potassium aluminyl compound [K{Al(NON)}]2 with tBu3PAuI. Computational studies of the complex, includ…
Corroles with Group 15 Ions. 2. Synthesis and Characterization of Octaethylcorroles Containing a Phosphorus Central Atom
2001
The synthesis, spectroscopic characterization, and electrochemistry of five new phosphorus corroles are reported. The investigated complexes contain alkyl, aryl, oxo, or hydrido axial ligands and are represented as (OEC)P(H)2, (OEC)P(CH3)2, (OEC)P(C6H5)2, (OEC)P=O, and [(OEC)P(CH3)]+ClO4-, where OEC is the trianion of octaethylcorrole. The products of electrooxidation and/or electroreduction were also characterized by UV-vis and ESR spectroscopy. Correlations are shown to exist between reversible half-wave potentials for the first oxidation and first reduction of each compound and the combined electronegativity of the central ion and the axial ligand(s). The electrochemical HOMO-LUMO gap, d…
Assembling Magnetic Blocks: A Strategy to Control the Nuclearity and Magnetic Properties of Polynuclear Complexes
1996
Synthetic strategies dealing with the polymerization of either di-μ-hydroxocopper(II) complexes or 2,2′-bipyrimidine (bpym)-containing first row transition metal ions allow the preparation of polynuclear compounds whose structures and magnetic properties are presented here. The influence of structural and chemical parameters on the magnitude of the singlet-triplet energy gap (J) in di-μ-hydroxocopper(II) complexes [LCu(OH)2CuL]2+ with L = 2,2′-bipyridine (bpy) and bpym is analyzed and discussed. Special attention is devoted to nature of the counterion which allows the preparation of hydroxo-bridge copper(II) cubane and double cubane type complexes where all the intramolecular magnetic inter…
On the aromaticity of uracil and its 5-halogeno derivatives as revealed by theoretically derived geometric and magnetic indexes
2020
AbstractThe problem of aromaticity in heterocyclic rings of uracil and its 5-halogenoderivatives (5XU) was analyzed theoretically by calculating modified harmonic oscillator model of aromaticity (HOMA) for Heterocycle Electron Delocalization (HOMHED), nucleus-independent chemical shift parameters (NICS) and the so-called scan experiments, using helium-3 atom as a magnetic probe. The impact of halogen electronegativity on C5 atom’s NBO charges was also investigated. Water, as a polar environment, has a negligible impact on 5XU aromaticity. The most stable diketo tautomer shows a very low aromaticity while the “rare” dihydroxy form (tautomer No 6) is aromatic and resembles benzene. This is in…
Restricted rotation in unbridged sandwich complexes: rotational behavior of closo-[Co(eta 5-NC4H4)(C2B9H11)] derivatives.
2005
Rotation about the centroid/ metal/centroid axis in ferrocene is facile; the activation energy is 1-5 kcal mol - 1 . The structurally similar sandwich complexes derived from closo-[3-Co(η 5 -NC 4 H 4 )-1,2-C 2 B 9 H 1 1 ] (1) have a different rotational habit. In 1, the cis rotamer in which the pyrrolyl nitrogen atom bisects the carboranyl cluster atoms is 3.5 kcal mol - 1 more stable in energy than the rotamer that is second lowest in energy. This cis rotamer is wide, spanning 216°, and may be split into three rotamers of almost equal energy by substituting the N and the carboranyl carbon atoms adequately. To support this statement, closo-[3-Co(η 5 -NC 4 H 4 )-1,2-(CH 3 ) 2 -1,2-C 2 B 9 H …
Twin studies on the association of physical activity with cognitive and cerebral outcomes
2020
Regular physical activity (PA) offers positive effects on the human body. However, the effects of PA on cognition and in the brain are less clear. In this paper, we narratively review the relationship of PA with cognition and dementia, first from general perspective and then through genetically informed studies on the topic. Then we move on to imaging studies on exercise and brain anatomy first by presenting an overall picture of the topic and then discussing brain imaging studies addressing PA and brain structure in twins in more detailed way. Regarding PA and cognition or dementia, genetically informed studies are uncommon, even though the relationship between PA and cognitive ageing has …
Somatosensory Deviance Detection ERPs and Their Relationship to Analogous Auditory ERPs and Interoceptive Accuracy
2022
Abstract. Automatic deviance detection has been widely explored in terms of mismatch responses (mismatch negativity or mismatch response) and P3a components of event-related potentials (ERPs) under a predictive coding framework; however, the somatosensory mismatch response has been investigated less often regarding the different types of changes than its auditory counterpart. It is not known whether the deviance detection responses from different modalities correlate, reflecting a general prediction error mechanism of the central nervous system. Furthermore, interoceptive functions have been associated with predictive coding theory, but whether interoceptive accuracy correlates with devian…