1,771 research outputs found
Time-resolved velocity map imaging of methyl elimination from photoexcited anisole
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 ĻĻ* 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 1ĻĻ* 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
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 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 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
Chemical composition and characterization of thermoplastic starch biomicrocomposites and hybrids, reinforced with latex and cellulose microparticles
Excited-state dynamics of a two-photon-activatable ruthenium prodrug
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 (620ā1000ā
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
This paper describes the application of a generalized effective stress soil model, MITāS1, 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 āHauptbahnhofā 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 ināsitu 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 tieāback 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
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?
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. Childrenās health status was scored across eight attributes of the HUI3āvision, 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 childās 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
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·sā 1Ā·mgā 1) as did citrate synthase activity (CSA: 206 Ā± 18; 129 Ā± 6; 82 Ā± 6 nmolĀ·mgā 1Ā·minā 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·mgā 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 ALZHEIMERāS DISEASE
Background: Alzheimerās 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 Alzheimerās disease. In the present study we tried to figure out possible
changes of the Purkinje cells in Alzheimerās 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 Alzheimerās 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 Alzheimerās 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 Alheimerās
disease
Duration and Time Trends in Hospital Stay for Very Preterm Infants Differ Across European Regions
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