65 research outputs found
Theta Functions, Elliptic Hypergeometric Series, and Kawanaka's Macdonald Polynomial Conjecture
We give a new theta-function identity, a special case of which is utilised to
prove Kawanaka's Macdonald polynomial conjecture. The theta-function identity
further yields a transformation formula for multivariable elliptic
hypergeometric series which appears to be new even in the one-variable, basic
case
Cornforth–Evans Transition States in Stereocontrolled Allylborations of Epoxy Aldehydes
Allylboration reactions rank among the most reliable tools in organic synthesis. Herein, we report a general synthesis of trifunctionalized allylboronates and systematic investigations of their stereocontrolled transformations with substituted aldehyde substrates, in order to efficiently access diverse, highly substituted target substrates. A peculiar transition in stereocontrol was observed from the polar Felkin–Anh (PFA) to the Cornforth–Evans (CE) model for alkoxy‐ and epoxy‐substituted aldehydes. CE‐type transition states were uniformly identified as minima in advanced, DFT‐based computational studies of allylboration reactions of epoxy aldehydes, conforming well to the experimental data, and highlighting the underestimated relevance of this model. Furthermore, a mechanism‐based rationale for the substitution pattern of the epoxide was delineated that ensures high levels of stereocontrol and renders α,β‐epoxy aldehydes generally applicable substrates for target synthesis
Complexes of Iron(II) with silylated pentalene ligands; building blocks for homo- and heterobimetallics
A range of iron(II) complexes incorporating the silylated pentalene ligands (Pn†H = 1,4-{SiiPr3}2C8H5 and Pn† = 1,4-{SiiPr3}2C8H4) have been investigated as model molecules/building blocks for metallocene-based polymers. Six complexes have been synthesised and extensively characterised by a range of techniques, including by cyclic voltammetry and X-ray diffraction studies. Amongst these compounds are the homobimetallic [Cp∗Fe]2(μ-Pn†) which is a fused analogue of biferrocene, and the 3d/4s heterobimetallic [Cp∗Fe(η5-Pn†)][K] which forms an organometallic polymer in the solid state. DFT calculations on model mono-Fe(η5-Pn) compounds reveal the charge densities on the uncoordinated carbon atoms of the pentalene ligand, and hence the potential for incorporating these units into heteronuclear bimetallic complexes is assessed
Congenital Hydrocephalus and Abnormal Subcommissural Organ Development in Sox3 Transgenic Mice
Congenital hydrocephalus (CH) is a life-threatening medical condition in which excessive accumulation of CSF leads to ventricular expansion and increased intracranial pressure. Stenosis (blockage) of the Sylvian aqueduct (Aq; the narrow passageway that connects the third and fourth ventricles) is a common form of CH in humans, although the genetic basis of this condition is unknown. Mouse models of CH indicate that Aq stenosis is associated with abnormal development of the subcommmissural organ (SCO) a small secretory organ located at the dorsal midline of the caudal diencephalon. Glycoproteins secreted by the SCO generate Reissner's fibre (RF), a thread-like structure that descends into the Aq and is thought to maintain its patency. However, despite the importance of SCO function in CSF homeostasis, the genetic program that controls SCO development is poorly understood. Here, we show that the X-linked transcription factor SOX3 is expressed in the murine SCO throughout its development and in the mature organ. Importantly, overexpression of Sox3 in the dorsal diencephalic midline of transgenic mice induces CH via a dose-dependent mechanism. Histological, gene expression and cellular proliferation studies indicate that Sox3 overexpression disrupts the development of the SCO primordium through inhibition of diencephalic roof plate identity without inducing programmed cell death. This study provides further evidence that SCO function is essential for the prevention of hydrocephalus and indicates that overexpression of Sox3 in the dorsal midline alters progenitor cell differentiation in a dose-dependent manner
Worry and ruminative brooding: associations with cognitive and physical health in older adults
IntroductionMental health conditions are associated with cognition and physical function in older adults. We examined whether worry and ruminative brooding, key symptoms of certain mental health conditions, are related to subjective and/or objective measures of cognitive and physical (cardiovascular) health.MethodsWe used baseline data from 282 participants from the SCD-Well and Age-Well trials (178 female; agemean = 71.1 years). We measured worry and ruminative brooding using the Penn State Worry Questionnaire and the Ruminative Response Scale-brooding subscale. We assessed subjective physical health using the WHOQOL-Bref physical subscale, and objective physical health via blood pressure and modified versions of the Framingham Risk Score and Charlson Comorbidity Index. With subjective and objective cognition, we utilized the Cognitive Difficulties Scale and a global composite (modified Preclinical Alzheimer’s Cognitive Composite, PACC5, with the Wechsler Adult Intelligence Scale-IV, category fluency, Mattis Dementia Rating Scale-2, and either the California Verbal Learning Test or the Rey Auditory Verbal Learning Test). We conducted linear regressions, adjusted for education, age, sex and cohort.ResultsWorry and ruminative brooding were negatively associated with subjective physical health (worry: β = −0.245, 95%CI −0.357 to −0.133, p < 0.001; ruminative brooding: β = −0.224, 95%CI −0.334 to −0.113, p < 0.001) and subjective cognitive difficulties (worry: β = 0.196, 95%CI 0.091 to 0.302, p < 0.001; ruminative brooding: β = 0.239, 95%CI 0.133 to 0.346, p < 0.001). We did not observe associations between worry or ruminative brooding and any measure of objective health.DiscussionWorry and ruminative brooding may be common mechanisms associated with subjective but not objective health. Alternatively, cognitively unimpaired older adults may become aware of subtle changes not captured by objective measures used in this study. Interventions reducing worry and ruminative brooding may promote subjective physical and cognitive health; however, more research is needed to determine causality of the relationships
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