326 research outputs found
Quantum Lissajous Scars
A quantum scar - an enhancement of a quantum probability density in the
vicinity of a classical periodic orbit - is a fundamental phenomenon connecting
quantum and classical mechanics. Here we demonstrate that some of the
eigenstates of the perturbed two-dimensional anisotropic (elliptic) harmonic
oscillator are strongly scarred by the Lissajous orbits of the unperturbed
classical counterpart. In particular, we show that the occurrence and geometry
of these quantum Lissajous scars are connected to the anisotropy of the
harmonic confinement, but unlike the classical Lissajous orbits the scars
survive under a small perturbation of the potential. This Lissajous scarring is
caused by the combined effect of the quantum (near) degeneracies in the
unperturbed system and the localized character of the perturbation.
Furthermore, we discuss experimental schemes to observe this
perturbation-induced scarring.Comment: 6 pages, 3 figure
Investigation of common, low-frequency and rare genome-wide variation in anorexia nervosa
Correction: Volume: 23 Issue: 9 DOI: 10.1038/mp.2017.202 Published: SEP 2018Anorexia nervosa (AN) is a complex neuropsychiatric disorder presenting with dangerously low body weight, and a deep and persistent fear of gaining weight. To date, only one genome-wide significant locus associated with AN has been identified. We performed an exome-chip based genome-wide association studies (GWAS) in 2158 cases from nine populations of European origin and 15 485 ancestrally matched controls. Unlike previous studies, this GWAS also probed association in low-frequency and rare variants. Sixteen independent variants were taken forward for in silico and de novo replication (11 common and 5 rare). No findings reached genome-wide significance. Two notable common variants were identified: rs10791286, an intronic variant in OPCML (P = 9.89 x 10(-6)), and rs7700147, an intergenic variant (P = 2.93 x 10(-5)). No low-frequency variant associations were identified at genome-wide significance, although the study was well-powered to detect low-frequency variants with large effect sizes, suggesting that there may be no AN loci in this genomic search space with large effect sizes.Peer reviewe
Resonant soft X-ray Raman scattering of NiO
Resonant soft X-ray Raman scattering measurements on NiO have been made at
photon energies across the Ni 2p absorption edges. The details of the spectral
features are identified as Raman scattering due to d-d and charge-transfer
excitations. The spectra are interpreted within the single impurity Anderson
model, including multiplets, crystal-field and charge-transfer effects. At
threshold excitation, the spectral features consists of triplet-triplet and
triplet-singlet transitions of the 3d8 configuration. For excitation energies
corresponding to the charge-transfer region in the Ni 2p X-ray absorption
spectrum of NiO, the emission spectra are instead dominated by charge-transfer
transitions to the 3d9L-1 final state. Comparisons of the final states with
other spectroscopical techniques are also made.Comment: 9 pages, 2 figures, 2 tables,
http://iopscience.iop.org/0953-8984/14/13/32
Validirane RP-RP-HPLC i TLC metode za simultano odreÄivanje tamsulozin hidroklorida i finasterida u istom dozirnom pripravku
Reversed phase high-performance liquid chromatography (RP-HPLC) and thin-layer chromatography (TLC) methods have been developed and validated for simultaneous estimation of tamsulosin hydrochloride and finasteride in bulk drug and in combined dosage forms. RP-HPLC separation was achieved on a Phenomenex C18 column using methanol/0.02 mol L-1 ammonium acetate buffer/triethylamine (79.9 + 20 + 0.1, V/V/V) (pH 9.2) as mobile phase. The TLC separation was achieved on an aluminium-backed layer of silica gel 60F254 using toluene/methanol/triethylamine (9 + 1.5 + 1, V/V/V) as eluent. Quantification was achieved with photodiode array (PDA) detection at 235 nm over the concentration range 0.5â16 and 150 ”g mL1 with mean recovery of 99.8 ± 0.9 and 100.0 ± 0.8 % for tamsulosin hydrochloride and finasteride, respectively, by the RP-HPLC method. Quantification was achieved with UV detection at 270 nm over the concentration range 100â2000 ng per spot and 250â5000 ng per spot with mean recovery of 98.9 ± 0.9 and 99.6 ± 0.7 % for tamsulosin hydrochloride and finasteride, respectively, by the TLC method. Both methods are simple, precise, accurate and sensitive and are applicable to the simultaneous determination of tamsulosin hydrochloride and finasteride in bulk drug and in combined dosage forms.U radu su opisani razvoj i validacija inverzno fazne kromatografije visoke uÄinkovitosti (RP-HPLC) i tankoslojne kromatografije (TLC) za simultano odreÄivanje tamsulozin hidroklorida i finasterida kao Äistih supstancija i u kombiniranim tabletama. Za RP-HPLC odjeljivanje koriĆĄtena je Phenomenex C18 kolona (250 mm, 4,6 mm, 5 ”m) i metanol/0,02 mol Lâ1 pufer s amonijevim acetatom/trietilamin (79,9+20+0,1, V/V/V) (pH 9,2) kao pokretna faza, pri protoku 1 mL min-1. TLC odjeljivanje raÄeno je na silikagelu 60F254 na aluminijskoj podlozi, koristeÄi toluen/metanol/trietilamin (9+1,5+1, V/V/V) kao eluens. Za detekciju u RP-HPLC metodi koriĆĄtena je fotodioda (PDA) pri 235 nm te je provedena kvantitacija u koncentracijskom podruÄju 0,5â16 ”g mLâ1 i 1â50 ”g mLâ1, uz srednji analitiÄki povrat od 99,8 ± 0,9 % za tamsulozin hidroklorid i 100,0 ± 0,8 % za finasterid. Za kvantitaciju u TLC metodi koriĆĄtena je UV detekcija pri 270 nm u koncentracijskom podruÄju 100â2000 ng po toÄki za tamsulozin hidroklorid i 250â5000 ng po toÄki za finasterid, uz srednji analitiÄki povrat od 98,9 ± 0,9, odnosno 99,6 ± 0,7 %. Obje metode su jednostavne, precizne, toÄne i osjetljive i mogu se primijeniti za simultano odreÄivanje tamsulozin hidroklorida i finasterida kao Äistih supstancija i u kombiniranim dozirnim oblicima
Local distortion in LaCoO3 and PrCoO3: EXAFS, XRD and XANES studies
Room temperature Co K-edge extended x-ray absorption fine structure (EXAFS),
x-ray absorption near edge structure (XANES) including pre-edge and x-ray
diffraction (XRD) studies are carried out on LaCoO3 and PrCoO3. The Co-O,
Co-La/Pr and Co-Co bond lengths are obtained from EXAFS analysis and compared
with those obtained from XRD. The EXAFS analysis of data indicates that CoO6
octahedron is distorted in both LaCoO3 and PrCoO3. Such distortion is expected
in orthorhombic PrCoO3 but not in rhombohedral LaCoO3. This distortion in CoO6
octahedron is attributed to Jahn-Teller active Co3+ ion in intermediate spin
state in these compounds. Higher shell studies reveal that Debye-Waller (DW)
factors of Co-Pr and Co-Co bonds in PrCoO3 are more in comparison to Co-La and
Co-Co bonds in LaCoO3 indicating that these bonds are structurally more
disordered in PrCoO3. The comparison of Co-Co bond lengths and corresponding DW
factors indicates that the structural disorder plays an important role in
deciding the insulating properties of these compounds. XANES studies have shown
changes in the intensities and positions of different near edge features.Comment: 22 pages, 8 figures, 2 tables. To appear in J. Phys.: Condens. Matte
Deconvolving Instrumental and Intrinsic Broadening in Excited State X-ray Spectroscopies
Intrinsic and experimental mechanisms frequently lead to broadening of
spectral features in excited-state spectroscopies. For example, intrinsic
broadening occurs in x-ray absorption spectroscopy (XAS) measurements of heavy
elements where the core-hole lifetime is very short. On the other hand,
nonresonant x-ray Raman scattering (XRS) and other energy loss measurements are
more limited by instrumental resolution. Here, we demonstrate that the
Richardson-Lucy (RL) iterative algorithm provides a robust method for
deconvolving instrumental and intrinsic resolutions from typical XAS and XRS
data. For the K-edge XAS of Ag, we find nearly complete removal of ~9.3 eV FWHM
broadening from the combined effects of the short core-hole lifetime and
instrumental resolution. We are also able to remove nearly all instrumental
broadening in an XRS measurement of diamond, with the resulting improved
spectrum comparing favorably with prior soft x-ray XAS measurements. We present
a practical methodology for implementing the RL algorithm to these problems,
emphasizing the importance of testing for stability of the deconvolution
process against noise amplification, perturbations in the initial spectra, and
uncertainties in the core-hole lifetime.Comment: 35 pages, 13 figure
Cord blood epigenome-wide meta-analysis in six European-based child cohorts identifies signatures linked to rapid weight growth
BACKGROUND: Rapid postnatal growth may result from exposure in utero or early life to adverse conditions and has been associated with diseases later in life and, in particular, with childhood obesity. DNA methylation, interfacing early-life exposures and subsequent diseases, is a possible mechanism underlying early-life programming. METHODS: Here, a meta-analysis of Illumina HumanMethylation 450K/EPIC-array associations of cord blood DNA methylation at single CpG sites and CpG genomic regions with rapid weight growth at 1 year of age (defined with reference to WHO growth charts) was conducted in six European-based child cohorts (ALSPAC, ENVIRONAGE, Generation XXI, INMA, PiccolipiĂč, and RHEA, N = 2003). The association of gestational age acceleration (calculated using the Bohlin epigenetic clock) with rapid weight growth was also explored via meta-analysis. Follow-up analyses of identified DNA methylation signals included prediction of rapid weight growth, mediation of the effect of conventional risk factors on rapid weight growth, integration with transcriptomics and metabolomics, association with overweight in childhood (between 4 and 8 years), and comparison with previous findings. RESULTS: Forty-seven CpGs were associated with rapid weight growth at suggestive p-value <1e-05 and, among them, three CpGs (cg14459032, cg25953130 annotated to ARID5B, and cg00049440 annotated to KLF9) passed the genome-wide significance level (p-value <1.25e-07). Sixteen differentially methylated regions (DMRs) were identified as associated with rapid weight growth at false discovery rate (FDR)-adjusted/Siddak p-values < 0.01. Gestational age acceleration was associated with decreasing risk of rapid weight growth (p-value = 9.75e-04). Identified DNA methylation signals slightly increased the prediction of rapid weight growth in addition to conventional risk factors. Among the identified signals, three CpGs partially mediated the effect of gestational age on rapid weight growth. Both CpGs (N=3) and DMRs (N=3) were associated with differential expression of transcripts (N=10 and 7, respectively), including long non-coding RNAs. An AURKC DMR was associated with childhood overweight. We observed enrichment of CpGs previously reported associated with birthweight. CONCLUSIONS: Our findings provide evidence of the association between cord blood DNA methylation and rapid weight growth and suggest links with prenatal exposures and association with childhood obesity providing opportunities for early prevention
Measurement of tamsulosin in human serum by liquid chromatography-tandem mass spectrometry
AbstractA simple, sensitive and robust method to extract tamsulosin from human serum, and quantify by liquid chromatographyâtandem mass spectrometry (LCâMS/MS) was developed and validated and is applicable as a measure of compliance in clinical research. Tamsulosin was extracted from human serum (100ÎŒL) via liquidâliquid extraction with methyl tert-butyl ether (2mL) following dilution with 0.1M ammonium hydroxide (100ÎŒL), achieving 99.9% analyte recovery. Internal standard, d9-finasteride, was synthesised in-house. Analyte and internal standard were separated on an AscentisÂź Express C18 (100mmĂ3mm, 2.7ÎŒm) column using a gradient elution with mobile phases methanol and 2mM aqueous ammonium acetate (5:95, v/v). Total run-time was 6min. Tamsulosin was quantified using a triple quadrupole mass spectrometer operated in multi-reaction-monitoring (MRM) mode using positive electrospray ionisation. Mass transitions monitored for quantitation were: tamsulosin m/z 409â228 and d9-finasteride m/z 382â318, with the structural formulae of ions confirmed by Fourier transform ion cyclotron resonance mass spectrometry (within 10ppm). The limit of quantitation was 0.2ng/mL, and the method was validated in the linear range 0.2â50ng/mL with acceptable inter- and intra-assay precision and accuracy and stability suitable for routine laboratory practice. The method was successfully applied to samples taken from research volunteers in a clinical study of benign prostatic hyperplasia
Electronic structure investigation of CoO by means of soft X-ray scattering
The electronic structure of CoO is studied by resonant inelastic soft X-ray
scattering spectroscopy using photon energies across the Co 2p absorption
edges. The different spectral contributions from the energy-loss structures are
identified as Raman scattering due to d-d and charge-transfer excitations. For
excitation energies close to the L3 resonance, the spectral features are
dominated by quartet-quartet and quartet-doublet transitions of the 3d7
configuration. At excitation energies corresponding to the satellites in the Co
2p X-ray absorption spectrum of CoO, the emission features are instead
dominated by charge-transfer transitions to the 3d8L-1 final state. The spectra
are interpreted and discussed with the support of simulations within the single
impurity Anderson model with full multiplet effects which are found to yield
consistent spectral functions to the experimental data.Comment: 8 pages, 2 figures, 2 tables,
http://link.aps.org/doi/10.1103/PhysRevB.65.20510
- âŠ