Second-trimester Maternal Serum Quadruple Test for Down Syndrome Screening: A Taiwanese Population-based Study

SummaryObjectiveTo assess the usefulness of quadruple test screening for Down syndrome in Taiwan.Materials and MethodsMaternal serum concentrations of a-fetoprotein, human chorionic gonadotropin, unconjugated estriol, and inhibin A were measured in 21,481 pregnant women from 15 to 20 weeks of gestation.ResultsOf the 21,481 women, 977 returned values greater than the high-risk cut-off value (1 in 270). Most of these women (86.2%) decided to have an invasive procedure for genetic diagnosis. Nine cases of Down syndrome and 19 cases of other chromosomal anomalies were detected prenatally. Two children with Down syndrome were diagnosed after delivery even though a low estimated risk was determined following the quadruple test. The detection rate was 81.8% (nine out of 11 cases), with a 4.4% false-positive rate. The median multiple of the median value for a-fetoprotein, human chorionic gonadotropin, unconjugated estriol and inhibin A were 0.87, 2.34, 0.77 and 2.16, respectively, in affected cases.ConclusionThis is the first study of the quadruple test for Down syndrome in a Chinese population. Our findings suggested that the second-trimester quadruple test provides an effective screening tool for Down syndrome in Taiwan

Observations of Coronal Mass Ejections with the Coronal Multichannel Polarimeter

The Coronal Multichannel Polarimeter (CoMP) measures not only the polarization of coronal emission, but also the full radiance profiles of coronal emission lines. For the first time, CoMP observations provide high-cadence image sequences of the coronal line intensity, Doppler shift and line width simultaneously in a large field of view. By studying the Doppler shift and line width we may explore more of the physical processes of CME initiation and propagation. Here we identify a list of CMEs observed by CoMP and present the first results of these observations. Our preliminary analysis shows that CMEs are usually associated with greatly increased Doppler shift and enhanced line width. These new observations provide not only valuable information to constrain CME models and probe various processes during the initial propagation of CMEs in the low corona, but also offer a possible cost-effective and low-risk means of space weather monitoring.Comment: 6 figures. Will appear in the special issue of Coronal Magnetism, Sol. Phy

Characterization of halogen-bridged binuclear metal complexes as hybridized two-band materials

We study the electronic structure of halogen-bridged binuclear metal (MMX) complexes with a two-band Peierls-Hubbard model. Based on a symmetry argument, various density-wave states are derived and characterized. The ground-state phase diagram is drawn within the Hartree-Fock approximation, while the thermal behavior is investigated using a quantum Monte Carlo method. All the calculations conclude that a typical MMX compound Pt_2(CH_3CS_2)_4I should indeed be regarded as a d-p-hybridized two-band material, where the oxidation of the halogen ions must be observed even in the ground state, whereas another MMX family (NH_4)_4[Pt_2(P_2O_5H_2)_4X] may be treated as single-band materials.Comment: 16 pages, 11 figures embedded, to be published in Phys. Rev.

Doping and temperature dependence of incommensurate antiferromagnetism in underdoped lanthanum cuprates

The doping, temperature and energy dependence of the dynamical spin structure factors of the underdoped lanthanum cuprates in the normal state is studied within the t-J model using the fermion-spin transformation technique. Incommensurate peaks are found at $[(1\pm\delta)\pi,\pi]$, $[\pi,(1\pm\delta)\pi]$ at relatively low temperatures with $\delta$ linearly increasing with doping at the beginning and then saturating at higher dopings. These peaks broaden and weaken in amplitude with temperature and energy, in good agreement with experiments. The theory also predicts a rotation of these peaks by $\pi/4$ at even higher temperatures, being shifted to $[(1\pm \delta/\sqrt{2})\pi,(1\pm \delta/\sqrt{2})\pi]$.Comment: 11 pages, PDF file, six figures are included, accepted for publication in Physical Review

Magnetism in the dilute Kondo lattice model

The one dimensional dilute Kondo lattice model is investigated by means of bosonization for different dilution patterns of the array of impurity spins. The physical picture is very different if a commensurate or incommensurate doping of the impurity spins is considered. For the commensurate case, the obtained phase diagram is verified using a non-Abelian density-matrix renormalization-group algorithm. The paramagnetic phase widens at the expense of the ferromagnetic phase as the $f$-spins are diluted. For the incommensurate case, antiferromagnetism is found at low doping, which distinguishes the dilute Kondo lattice model from the standard Kondo lattice model.Comment: 11 pages, 2 figure

Cosmological constraints on the generalized holographic dark energy

We use the Markov ChainMonte Carlo method to investigate global constraints on the generalized holographic (GH) dark energy with flat and non-flat universe from the current observed data: the Union2 dataset of type supernovae Ia (SNIa), high-redshift Gamma-Ray Bursts (GRBs), the observational Hubble data (OHD), the cluster X-ray gas mass fraction, the baryon acoustic oscillation (BAO), and the cosmic microwave background (CMB) data. The most stringent constraints on the GH model parameter are obtained. In addition, it is found that the equation of state for this generalized holographic dark energy can cross over the phantom boundary wde =-1.Comment: 14 pages, 5 figures. arXiv admin note: significant text overlap with arXiv:1105.186

(Sub)mm Interferometry Applications in Star Formation Research

This contribution gives an overview about various applications of (sub)mm interferometry in star formation research. The topics covered are molecular outflows, accretion disks, fragmentation and chemical properties of low- and high-mass star-forming regions. A short outlook on the capabilities of ALMA is given as well.Comment: 20 pages, 7 figures, in proceedings to "2nd European School on Jets from Young Star: High Angular Resolution Observations". A high-resolution version of the paper can be found at http://www.mpia.de/homes/beuther/papers.htm

Galaxy Clusters as Reservoirs of Heavy Dark Matter and High-Energy Cosmic Rays: Constraints from Neutrino Observations

Galaxy Clusters (GCs) are the largest reservoirs of both dark matter and cosmic rays (CRs). Dark matter self-annihilation can lead to a high luminosity in gamma rays and neutrinos, enhanced by a strong degree of clustering in dark matter substructures. Hadronic CR interactions can also lead to a high luminosity in gamma rays and neutrinos, enhanced by the confinement of CRs from cluster accretion/merger shocks and active galactic nuclei. We show that IceCube/KM3Net observations of high-energy neutrinos can probe the nature of GCs and the separate dark matter and CR emission processes, taking into account how the results depend on the still-substantial uncertainties. Neutrino observations are relevant at high energies, especially at >10 TeV. Our results should be useful for improving experimental searches for high-energy neutrino emission. Neutrino telescopes are sensitive to extended sources formed by dark matter substructures and CRs distributed over large scales. Recent observations by Fermi and imaging atmospheric Cherenkov telescopes have placed interesting constraints on the gamma-ray emission from GCs. We also provide calculations of the gamma-ray fluxes, taking into account electromagnetic cascades inside GCs, which can be important for injections at sufficiently high energies. This also allows us to extend previous gamma-ray constraints to very high dark matter masses and significant CR injections at very high energies. Using both neutrinos and gamma rays, which can lead to comparable constraints, will allow more complete understandings of GCs. Neutrinos are essential for some dark matter annihilation channels, and for hadronic instead of electronic CRs. Our results suggest that the multi-messenger observations of GCs will be able to give useful constraints on specific models of dark matter and CRs. [Abstract abridged.]Comment: 31 pages, 20 figures, 1 table, accepted for publication in JCAP, references and discussions adde

An Extreme Solar Event of 20 January 2005: Properties of the Flare and the Origin of Energetic Particles

The extreme solar and SEP event of 20 January 2005 is analyzed from two perspectives. Firstly, we study features of the main phase of the flare, when the strongest emissions from microwaves up to 200 MeV gamma-rays were observed. Secondly, we relate our results to a long-standing controversy on the origin of SEPs arriving at Earth, i.e., acceleration in flares, or shocks ahead of CMEs. All emissions from microwaves up to 2.22 MeV line gamma-rays during the main flare phase originated within a compact structure located just above sunspot umbrae. A huge radio burst with a frequency maximum at 30 GHz was observed, indicating the presence of a large number of energetic electrons in strong magnetic fields. Thus, protons and electrons responsible for flare emissions during its main phase were accelerated within the magnetic field of the active region. The leading, impulsive parts of the GLE, and highest-energy gamma-rays identified with pi^0-decay emission, are similar and correspond in time. The origin of the pi^0-decay gamma-rays is argued to be the same as that of lower energy emissions. We estimate the sky-plane speed of the CME to be 2000-2600 km/s, i.e., high, but of the same order as preceding non-GLE-related CMEs from the same active region. Hence, the flare itself rather than the CME appears to determine the extreme nature of this event. We conclude that the acceleration, at least, to sub-relativistic energies, of electrons and protons, responsible for both the flare emissions and the leading spike of SEP/GLE by 07 UT, are likely to have occurred simultaneously within the flare region. We do not rule out a probable contribution from particles accelerated in the CME-driven shock for the leading GLE spike, which seemed to dominate later on.Comment: 34 pages, 14 Postscript figures. Solar Physics, accepted. A typo corrected. The original publication is available at http://www.springerlink.co