95 research outputs found
Evolution of Linear Absorption and Nonlinear Optical Properties in V-Shaped Ruthenium(II)-Based Chromophores
In this article, we describe a series of complexes with electron-rich cis-{Ru^(II)(NH_3)_4}^(2+) centers coordinated to two pyridyl ligands bearing N-methyl/arylpyridinium electron-acceptor groups. These V-shaped dipolar species are new, extended members of a class of chromophores first reported by us (Coe, B. J. et al. J. Am. Chem. Soc. 2005, 127, 4845β4859). They have been isolated as their PF_6β salts and characterized by using various techniques including ^1H NMR and electronic absorption spectroscopies and cyclic voltammetry. Reversible Ru^(III/II) waves show that the new complexes are potentially redox-switchable chromophores. Single crystal X-ray structures have been obtained for four complex salts; three of these crystallize noncentrosymmetrically, but with the individual molecular dipoles aligned largely antiparallel. Very large molecular first hyperpolarizabilities Ξ² have been determined by using hyper-Rayleigh scattering (HRS) with an 800 nm laser and also via Stark (electroabsorption) spectroscopic studies on the intense, visible d β Ο^* metal-to-ligand charge-transfer (MLCT) and Ο β Ο^* intraligand charge-transfer (ILCT) bands. The latter measurements afford total nonresonant Ξ²_0 responses as high as ca. 600 Γ 10^(β30) esu. These pseudo-C_(2v) chromophores show two substantial components of the Ξ² tensor, Ξ²_(zzz) and Ξ²_(zyy), although the relative significance of these varies with the physical method applied. According to HRS, Ξ²_(zzz) dominates in all cases, whereas the Stark analyses indicate that Ξ²_(zyy) is dominant in the shorter chromophores, but Ξ²_(zzz) and Ξ²_(zyy) are similar for the extended species. In contrast, finite field calculations predict that Ξ²_(zyy) is always the major component. Time-dependent density functional theory calculations predict increasing ILCT character for the nominally MLCT transitions and accompanying blue-shifts of the visible absorptions, as the ligand Ο-systems are extended. Such unusual behavior has also been observed with related 1D complexes (Coe, B. J. et al. J. Am. Chem. Soc. 2004, 126, 3880β3891)
'You can take a horse to water but you can't make it drink': Exploring children's engagement and resistance in family therapy
The final publication is available at Springer via http://dx.doi.org/10.1007/s10591-012-9220-8Childrenβs engagement and disengagement, adherence and non-adherence, compliance and non-compliance in healthcare have important implications for services. In family therapy mere attendance to the appointments is no guarantee of engaging in the treatment process and as children are not the main initiators of attendance engaging them through the process can be a complex activity for professionals. Through a conversation analysis of naturally occurring family therapy sessions we explore the main discursive strategies that children employ in this context to passively and actively disengage from the therapeutic process and investigate how the therapists manage and attend to this. We note that children competently remove themselves from therapy through passive resistance, active disengagement, and by expressing their autonomy. Analysis reveals that siblings of the constructed βproblemβ child are given greater liberty in involvement. We conclude by demonstrating how therapists manage the delicate endeavour of including all family members in the process and how engagement and re-engagement are essential for meeting goals and discuss broader implications for healthcare and other settings where children may disengage
Brain-Derived Neurotrophic Factor Ameliorates Brain Stem Cardiovascular Dysregulation during Experimental Temporal Lobe Status Epilepticus
Background: Status epilepticus (SE) is an acute, prolonged epileptic crisis with a mortality rate of 20β30%; the underlying mechanism is not completely understood. We assessed the hypothesis that brain stem cardiovascular dysregulation occurs during SE because of oxidative stress in rostral ventrolateral medulla (RVLM), a key nucleus of the baroreflex loop; to be ameliorated by brain-derived neurotrophic factor (BDNF) via an antioxidant action. Methodology/Principal Findings: In a clinically relevant experimental model of temporal lobe SE (TLSE) using Sprague-Dawley rats, sustained hippocampal seizure activity was accompanied by progressive hypotension that was preceded by a reduction in baroreflex-mediated sympathetic vasomotor tone; heart rate and baroreflex-mediated cardiac responses remained unaltered. Biochemical experiments further showed concurrent augmentation of superoxide anion, phosphorylated p47 phox subunit of NADPH oxidase and mRNA or protein levels of BDNF, tropomyosin receptor kinase B (TrkB), angiotensin AT1 receptor subtype (AT1R), nitric oxide synthase II (NOS II) or peroxynitrite in RVLM. Whereas pretreatment by microinjection bilaterally into RVLM of a superoxide dismutase mimetic (tempol), a specific antagonist of NADPH oxidase (apocynin) or an AT1R antagonist (losartan) blunted significantly the augmented superoxide anion or phosphorylated p47 phox subunit in RVLM, hypotension and the reduced baroreflex-mediated sympathetic vasomotor tone during experimental TLSE, pretreatment with a recombinant human TrkB-Fc fusion protein or an antisense bdn
Investigating Behaviour and Population Dynamics of Striped Marlin (Kajikia audax) from the Southwest Pacific Ocean with Satellite Tags
Behaviour and distribution of striped marlin within the southwest Pacific Ocean were investigated using electronic tagging data collected from 2005β2008. A continuous-time correlated random-walk Kalman filter was used to integrate double-tagging data exhibiting variable error structures into movement trajectories composed of regular time-steps. This state-space trajectory integration approach improved longitude and latitude error distributions by 38.5 km and 22.2 km respectively. Using these trajectories as inputs, a behavioural classification model was developed to infer when, and where, βtransitingβ and βarea-restrictedβ (ARB) pseudo-behavioural states occurred. ARB tended to occur at shallower depths (108Β±49 m) than did transiting behaviours (127Β±57 m). A 16 day post-release period of diminished ARB activity suggests that patterns of behaviour were affected by the capture and/or tagging events, implying that tagged animals may exhibit atypical behaviour upon release. The striped marlin in this study dove deeper and spent greater time at β₯200 m depth than those in the central and eastern Pacific Ocean. As marlin reached tropical latitudes (20β21Β°S) they consistently reversed directions, increased swimming speed and shifted to transiting behaviour. Reversals in the tropics also coincided with increases in swimming depth, including increased time β₯250 m. Our research provides enhanced understanding of the behavioural ecology of striped marlin. This has implications for the effectiveness of spatially explicit population models and we demonstrate the need to consider geographic variation when standardizing CPUE by depth, and provide data to inform natural and recreational fishing mortality parameters
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