Controllable quantum scars in semiconductor quantum dots

Quantum scars are enhancements of quantum probability density along classical periodic orbits. We study the recently discovered phenomenon of strong, perturbation-induced quantum scarring in the two-dimensional harmonic oscillator exposed to a homogeneous magnetic field. We demonstrate that both the geometry and the orientation of the scars are fully controllable with a magnetic field and a focused perturbative potential, respectively. These properties may open a path into an experimental scheme to manipulate electric currents in nanostructures fabricated in a two-dimensional electron gas.Comment: 5 pages, 4 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 određivanje 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 0.5–16 and 150 µg 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 100–2000 ng per spot and 250–5000 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 učinkovitosti (RP-HPLC) i tankoslojne kromatografije (TLC) za simultano određivanje tamsulozin hidroklorida i finasterida kao čistih supstancija i u kombiniranim tabletama. Za RP-HPLC odjeljivanje korištena je Phenomenex C18 kolona (250 mm, 4,6 mm, 5 µm) i metanol/0,02 mol L–1 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 rađeno je na silikagelu 60F254 na aluminijskoj podlozi, koristeći toluen/metanol/trietilamin (9+1,5+1, V/V/V) kao eluens. Za detekciju u RP-HPLC metodi korištena je fotodioda (PDA) pri 235 nm te je provedena kvantitacija u koncentracijskom području 0,5–16 µg mL–1 i 1–50 µg mL–1, uz srednji analitički povrat od 99,8 ± 0,9 % za tamsulozin hidroklorid i 100,0 ± 0,8 % za finasterid. Za kvantitaciju u TLC metodi korištena je UV detekcija pri 270 nm u koncentracijskom području 100–2000 ng po točki za tamsulozin hidroklorid i 250–5000 ng po točki za finasterid, uz srednji analitički povrat od 98,9 ± 0,9, odnosno 99,6 ± 0,7 %. Obje metode su jednostavne, precizne, točne i osjetljive i mogu se primijeniti za simultano određivanje tamsulozin hidroklorida i finasterida kao čistih 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

Relativistic theory of magnetic scattering of x rays: Application to ferromagnetic iron

We present a detailed description of a first-principles formalism for magnetic scattering of circularly polar- ized x rays from solids in the framework of the fully relativistic spin-polarized multiple-scattering theory. The scattering amplitudes are calculated using a standard time-dependent perturbation theory to second order in the electron-photon interaction vertex. Particular attention is paid to understanding the relative importance of the positive- and negative-energy solutions of the Dirac equation to the scattering amplitude. The advantage of the present theory as compared with other recent works on magnetic x-ray scattering is that, being fully relativistic, spin-orbit coupling and spin-polarization effects are treated on an equal footing. Second, the electron Green’s function expressed in terms of the path operators in the multiple-scattering theory allows us to include the contribution of the crystalline environment to the scattering amplitude. To illustrate the use of the method we have done calculations on the anomalous magnetic scattering at the K , L_II , and L_III absorption edges of ferromagnetic iron

Relativistic Calculation of two-Electron one-Photon and Hypersatellite Transition Energies for 12≤Z≤3012\leq Z\leq30 Elements

Energies of two-electron one-photon transitions from initial double K-hole states were computed using the Dirac-Fock model. The transition energies of competing processes, the K$\alpha$ hypersatellites, were also computed. The results are compared to experiment and to other theoretical calculations.Comment: accepted versio

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, Piccolipiù, 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

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