613 research outputs found

    Don't blame the model:Reconsidering the network approach to psychopathology

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    The network approach to psychopathology is becoming increasingly popular. The motivation for this approach is to provide a replacement for the problematic common cause perspective and the associated latent variable model, where symptoms are taken to be mere effects of a common cause (the disorder itself). The idea is that the latent variable model is plausible for medical diseases, but unrealistic for mental disorders, which should rather be conceptualized as networks of directly interacting symptoms. We argue that this rationale for the network approach is misguided. Latent variable (or common cause) models are not inherently problematic, and there is not even a clear boundary where network models end and latent variable (or common cause) models begin. We also argue that focusing on this contrast has led to an unrealistic view of testing and finding support for the network approach, as well as an oversimplified picture of the relationship between medical diseases and mental disorders. As an alternative, we point out more essential contrasts, such as the contrast between dynamic and static modeling approaches that can provide a better framework for conceptualizing mental disorders. Finally, we discuss several topics and open problems that need to be addressed in order to make the network approach more concrete and to move the field of psychological network research forward. (PsycINFO Database Recor

    A Markov Chain Approach To Reconstruction Of Long Haplotypes

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    Haplotypes are important for association based gene mapping, but there are no practical laboratory methods for obtaining them directly from DNA samples. We propose simple Markov models for reconstruction of haplotypes for a given sample of multilocus genotypes. The models are aimed specifically for long marker maps, where linkage disequilibrium between markers may vary and be relatively weak. Such maps are ultimately used in chromosome or genome-wide association studies. Haplotyp

    Synthesis of Diaryl Hydroxyl Dicarboxylic Acids from Amino Acids

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    Herein we report a unique method for preparing diaryl hydroxyl dicarboxylic acids in a diastereospecific manner. The three-component reaction occurs between amino acid, aromatic aldehyde, and primary alcohol in alkaline solutions under microwave-assisted conditions. The dicarboxylic acids are isolated as sodium salts in high yields (up to 77%) by direct precipitation from the reaction solution. The experimental results suggest that the diastereospecificity originates from a [3,3]-sigmatropic rearrangement followed by a sodium-assisted hydride transfer. As further shown, the previously unreported dicarboxylic acids are easily turned into corresponding delta-lactones.Peer reviewe

    Precision mass measurements on neutron-rich rare-earth isotopes at JYFLTRAP - reduced neutron pairing and implications for the rr-process calculations

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    The rare-earth peak in the rr-process abundance pattern depends sensitively on both the astrophysical conditions and subtle changes in nuclear structure in the region. This work takes an important step elucidating the nuclear structure and reducing the uncertainties in rr-process calculations via precise atomic mass measurements at the JYFLTRAP double Penning trap. 158^{158}Nd, 160^{160}Pm, 162^{162}Sm, and 164166^{164-166}Gd have been measured for the first time and the precisions for 156^{156}Nd, 158^{158}Pm, 162,163^{162,163}Eu, 163^{163}Gd, and 164^{164}Tb have been improved considerably. Nuclear structure has been probed via two-neutron separation energies S2nS_{2n} and neutron pairing energy metrics DnD_n. The data do not support the existence of a subshell closure at N=100N=100. Neutron pairing has been found to be weaker than predicted by theoretical mass models. The impact on the calculated rr-process abundances has been studied. Substantial changes resulting in a smoother abundance distribution and a better agreement with the solar rr-process abundances are observed.Comment: 8 pages, 4 figures, accepted for publication in Physical Review Letter

    Electron-capture branch of 100Tc and tests of nuclear wave functions for double-beta decays

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    We present a measurement of the electron-capture branch of 100^{100}Tc. Our value, B(EC)=(2.6±0.4)×105B(\text{EC}) = (2.6 \pm 0.4) \times 10^{-5}, implies that the 100^{100}Mo neutrino absorption cross section to the ground state of 100^{100}Tc is roughly one third larger than previously thought. Compared to previous measurements, our value of B(EC)B(\text{EC}) prevents a smaller disagreement with QRPA calculations relevant to double-β\beta decay matrix elements

    Magnetic field stabilization for high-accuracy mass measurements on exotic nuclides

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    The magnetic-field stability of a mass spectrometer plays a crucial role in precision mass measurements. In the case of mass determination of short-lived nuclides with a Penning trap, major causes of instabilities are temperature fluctuations in the vicinity of the trap and pressure fluctuations in the liquid helium cryostat of the superconducting magnet. Thus systems for the temperature and pressure stabilization of the Penning trap mass spectrometer ISOLTRAP at the ISOLDE facility at CERN have been installed. A reduction of the fluctuations by at least one order of magnitude downto dT=+/-5mK and dp=+/-50mtorr has been achieved, which corresponds to a relative frequency change of 2.7x10^{-9} and 1.5x10^{-10}, respectively. With this stabilization the frequency determination with the Penning trap only shows a linear temporal drift over several hours on the 10 ppb level due to the finite resistance of the superconducting magnet coils.Comment: 23 pages, 13 figure
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