1,771 research outputs found

    Time-resolved velocity map imaging of methyl elimination from photoexcited anisole

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    To date, H-atom elimination from heteroaromatic molecules following UV excitation has been extensively studied, with the focus on key biological molecules such as chromophores of DNA bases and amino acids. Extending these studies to look at elimination of other non-hydride photoproducts is essential in creating a more complete picture of the photochemistry of these biomolecules in the gas-phase. To this effect, CH3 elimination in anisole has been studied using time resolved velocity map imaging (TR-VMI) for the first time, providing both time and energy information on the dynamics following photoexcitation at 200 nm. The extra dimension of energy afforded by these measurements has enabled us to address the role of Ļ€Ļƒ* states in the excited state dynamics of anisole as compared to the hydride counterpart (phenol), providing strong evidence to suggest that only CH3 fragments eliminated with high kinetic energy are due to direct dissociation involving a 1Ļ€Ļƒ* state. These measurements also suggest that indirect mechanisms such as statistical unimolecular decay could be contributing to the dynamics at much longer times

    Vortex lattices for ultracold bosonic atoms in a non-Abelian gauge potential

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    The use of coherent optical dressing of atomic levels allows the coupling of ultracold atoms to effective non-dynamical gauge fields. These can be used to generate effective magnetic fields, and have the potential to generate non-Abelian gauge fields. We consider a model of a gas of bosonic atoms coupled to a gauge field with U(2)U(2) symmetry, and with constant effective magnetic field. We include the effects of weak contact interactions by applying Gross-Pitaevskii mean-field theory. We study the effects of a U(2)U(2) non-Abelian gauge field on the vortex lattice phase induced by a uniform effective magnetic field, generated by an Abelian gauge field or, equivalently, by rotation of the gas. We show that, with increasing non-Abelian gauge field, the nature of the groundstate changes dramatically, with structural changes of the vortex lattice. We show that the effect of the non-Abelian gauge field is equivalent to the introduction of effective interactions with non-zero range. We also comment on the consequences of the non-Abelian gauge field for strongly correlated fractional quantum Hall states

    Excited-state dynamics of a two-photon-activatable ruthenium prodrug

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    We present a new approach to investigate how the photodynamics of an octahedral ruthenium(II) complex activated through two-photon absorption (TPA) differ from the equivalent complex activated through one-photon absorption (OPA). We photoactivated a RuII polypyridyl complex containing bioactive monodentate ligands in the photodynamic therapy window (620ā€“1000ā€…nm) by using TPA and used transient UV/Vis absorption spectroscopy to elucidate its reaction pathways. Density functional calculations allowed us to identify the nature of the initially populated states and kinetic analysis recovers a photoactivation lifetime of approximately 100ā€…ps. The dynamics displayed following TPA or OPA are identical, showing that TPA prodrug design may use knowledge gathered from the more numerous and easily conducted OPA studies

    Prediction and interpretation of the performance of a deep excavation in Berlin sand

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    This paper describes the application of a generalized effective stress soil model, MITā€S1, within a commercial finite element program, for simulating the performance of the support system for the 20m deep excavation of the M1 pit adjacent to the main station ā€œHauptbahnhofā€ in Berlin. The M1 pit was excavated underwater and supported by a perimeter diaphragm wall with a single row of prestressed anchors. Parameters for the soil model were based on an extensive program of laboratory tests on the local Berlin Sands. This calibration process highlights the practical difficulties in both measurements of critical state soil properties and in model parameter selection. The predictions of excavation performance are strongly affected by vertical profiles of two key state parameters, the initial earth pressure ratio, K0, and the inā€situ void ratio, e0. These are estimated from field dynamic penetration test data and geological history. The results show good agreement between computed and measured wall deflections and tieā€back forces for three instrumented sections. Much larger wall deflections were measured at a fourth section and may be due to spatial variability in sand properties that has not been considered in the current analyses. The results of this study highlight the importance of basic state parameter information for successful application of advanced soil models.National Science Foundation (U.S.) (Wester Europe program grant INT-0089508)German Academic Exchange Service (DAAD

    cuticleDB: a relational database of Arthropod cuticular proteins

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    BACKGROUND: The insect exoskeleton or cuticle is a bi-partite composite of proteins and chitin that provides protective, skeletal and structural functions. Little information is available about the molecular structure of this important complex that exhibits a helicoidal architecture. Scores of sequences of cuticular proteins have been obtained from direct protein sequencing, from cDNAs, and from genomic analyses. Most of these cuticular protein sequences contain motifs found only in arthropod proteins. DESCRIPTION: cuticleDB is a relational database containing all structural proteins of Arthropod cuticle identified to date. Many come from direct sequencing of proteins isolated from cuticle and from sequences from cDNAs that share common features with these authentic cuticular proteins. It also includes proteins from the Drosophila melanogaster and the Anopheles gambiae genomes, that have been predicted to be cuticular proteins, based on a Pfam motif (PF00379) responsible for chitin binding in Arthropod cuticle. The total number of the database entries is 445: 370 derive from insects, 60 from Crustacea and 15 from Chelicerata. The database can be accessed from our web server at . CONCLUSIONS: CuticleDB was primarily designed to contain correct and full annotation of cuticular protein data. The database will be of help to future genome annotators. Users will be able to test hypotheses for the existence of known and also of yet unknown motifs in cuticular proteins. An analysis of motifs may contribute to understanding how proteins contribute to the physical properties of cuticle as well as to the precise nature of their interaction with chitin

    Is there an association between early weight status and utility based health-related quality of life in young children?

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    Purpose Few studies focus on the health-related quality of life (HRQoL) of preschool children with overweight or obesity. This is relevant for evaluation of obesity prevention trials using a quality-adjusted life year (QALY) framework. This study examined the association between weight status in the preschool years and HRQoL at age 5 years, using a preference-based instrument. Methods HRQoL [based on parent proxy version of the Health Utilities Index Mark 3 (HUI3)] and weight status were measured in children born in Australia between 2007 and 2009. Childrenā€™s health status was scored across eight attributes of the HUI3ā€”vision, hearing, speech, ambulation, dexterity, emotion, cognition and pain, and these were used to calculate a multi-attribute utility score. Ordinary least squares (OLS), Tobit and two-part regressions were used to model the association between weight status and multi-attribute utility. Results Of the 368 children for whom weight status and HUI3 data were available, around 40% had overweight/obesity. After adjusting for childā€™s sex, maternal education, marital status and household income, no significant association between weight status in the preschool years and multi-attribute utility scores at 5 years was found. Conclusions Alternative approaches for capturing the effects of weight status in the preschool years on preference-based HRQoL outcomes should be tested. The application of the QALY framework to economic evaluations of obesity-related interventions in young children should also consider longitudinal effects over the life-course

    Mitochondrial function in heart failure: The impact of ischemic and non-ischemic etiology

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    Background Although cardiac mitochondrial dysfunction is associated with heart failure (HF), this is a complex syndrome with two predominant etiologies, ischemic HF (iHF) and non-ischemic HF (niHF), and the exact impact of mitochondrial dysfunction in these two distinct forms of HF is unknown. Methods and results To determine the impact of HF etiology on mitochondrial function, respiration was measured in permeabilized cardiac muscle fibers from patients with iHF (n = 17), niHF (n = 18), and healthy donor hearts (HdH). Oxidative phosphorylation capacity (OXPHOS), assessed as state 3 respiration, fell progressively from HdH to niHF, to iHF (Complex I + II: 54 Ā± 1; 34 Ā± 4; 27 Ā± 3 pmolĀ·sāˆ’ 1Ā·mgāˆ’ 1) as did citrate synthase activity (CSA: 206 Ā± 18; 129 Ā± 6; 82 Ā± 6 nmolĀ·mgāˆ’ 1Ā·mināˆ’ 1). Although still significantly lower than HdH, normalization of OXPHOS by CSA negated the difference in mass specific OXPHOS between iHF and niHF. Interestingly, Complex I state 2 respiration increased progressively from HdH, to niHF, to iHF, whether or not normalized for CSA (0.6 Ā± 0.2; 1.1 Ā± 0.3; 2.3 Ā± 0.3; pmolĀ·mgāˆ’ 1Ā·CSA), such that the respiratory control ratio (RCR), fell in the same manner across groups. Finally, both the total free radical levels (60 Ā± 6; 46 Ā± 4 AU) and level of mitochondrial derived superoxide (1.0 Ā± 0.2; 0.7 Ā± 0.1 AU) were greater in iHF compared to niHF, respectively. Conclusions Thus, the HF-related attenuation in OXPHOS actually appears to be independent of etiology when the lower mitochondrial content of iHF is taken into account. However, these findings provide evidence of deleterious intrinsic mitochondrial changes in iHF, compared to niHF, including greater proton leak, attenuated OXPHOS efficiency, and augmented free radical levels

    DENDRITIC AND SPINAL PATHOLOGY OF THE PURKINJE CELLS FROM THE HUMAN CEREBELLAR VERMIS IN ALZHEIMERā€™S DISEASE

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    Background: Alzheimerā€™s disease constitutes one of the main causes of dementia. It is clinically characterized by memory impairment, deterioration of intellectual faculties and loss of professional skills. Furthermore changes in equilibrium and limb coordination are clinically demonstrable in persons with Alzheimerā€™s disease. In the present study we tried to figure out possible changes of the Purkinje cells in Alzheimerā€™s disease brains. Subjects and methods: We studied the Purkinje cells from the vermis of the cerebellum in 5 Alzheimerā€™ disease brains Golgi technique. Results: In the Purkinje cells from the inferior surface of the cerebellar hemispheres severe dendritic and spinal pathology consisting of loss of distal dendritic segments and alterations of dendritic spine morphology can be noticed in Alzheimerā€™s disease brains. Conclusions: The morphological and morphometric estimation of the dendrites and the dendritic spines of the Purkinje cells from the inferior surface of the cerebellar hemispheres in Alzheimerā€™s disease brains revealed substantial alterations of the dendritic arborization and marked loss of the dendritic spines, which may be related to cognitive impairment and motor deficits in Alheimerā€™s disease

    Duration and Time Trends in Hospital Stay for Very Preterm Infants Differ Across European Regions

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    Contains fulltext : 199466.pdf (publisher's version ) (Open Access
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