On the Doppler Shift and Asymmetry of Stokes Profiles of Photospheric FeI and Chromospheric MgI Lines

We analyzed the full Stokes spectra using simultaneous measurements of the photospheric (FeI 630.15 and 630.25 nm) and chromospheric (MgI b2 517.27 nm) lines. The data were obtained with the HAO/NSO Advanced Stokes Polarimeter, about a near disc center sunspot region, NOAA AR 9661. We compare the characteristics of Stokes profiles in terms of Doppler shifts and asymmetries among the three spectral lines, which helps us to better understand the chromospheric lines and the magnetic and flow fields in different magnetic regions. The main results are: (1) For penumbral area observed by the photospheric FeI lines, Doppler velocities derived from Stokes I (Vi) are very close to those derived from linear polarization profiles (Vlp) but significantly different from those derived from Stokes V profiles (Vzc), which provides direct and strong evidence that the penumbral Evershed flows are magnetized and mainly carried by the horizontal magnetic component. (2) The rudimentary inverse Evershed effect observed by the MgI b2 line provides a qualitative evidence on its formation height that is around or just above the temperature minimum region. (3) Vzc and Vlp in penumbrae and Vzc in pores generally approach their Vi observed by the chromospheric MgI line, which is not the case for the photospheric FeI lines. (4) Outer penumbrae and pores show similar behavior of the Stokes V asymmetries that tend to change from positive values in the photosphere (FeI lines) to negative values in the low chromosphere (MgI line). (5) The Stokes V profiles in plage regions are highly asymmetric in the photosphere and more symmetric in the low chromosphere. (6) Strong red shifts and large asymmetries are found around the magnetic polarity inversion line within the common penumbra of the Delta spot. This study thus emphasizes the importance of spectro-polarimetry using chromospheric lines.Comment: 10 pages, 7 figures, accepted to The Astrophysical Journa

A study of the effectiveness of a phonetic and activity approach to the teaching of spelling in grade four,

Includes appendices. Thesis (M.A.)--Boston Universit

Analytical solution of a model for complex food webs

We investigate numerically and analytically a recently proposed model for food webs [Nature {\bf 404}, 180 (2000)] in the limit of large web sizes and sparse interaction matrices. We obtain analytical expressions for several quantities with ecological interest, in particular the probability distributions for the number of prey and the number of predators. We find that these distributions have fast-decaying exponential and Gaussian tails, respectively. We also find that our analytical expressions are robust to changes in the details of the model.Comment: 4 pages (RevTeX). Final versio

Profiling sex-biased gene expression during parthenogenetic reproduction in Daphnia pulex

<p>Abstract</p> <p>Background</p> <p>Sexual reproduction is a core biological function that is conserved throughout eukaryotic evolution, yet breeding systems are extremely variable. Genome-wide comparative studies can be effectively used to identify genes and regulatory patterns that are constrained to preserve core functions from those that may help to account for the diversity of animal reproductive strategies. We use a custom microarray to investigate gene expression in males and two reproductive stages of females in the crustacean <it>Daphnia pulex</it>. Most <it>Daphnia </it>species reproduce by cyclical parthenogenesis, alternating between sexual and clonal reproduction. Both sex determination and the switch in their mode of reproduction is environmentally induced, making <it>Daphnia </it>an interesting comparative system for the study of sex-biased and reproductive genes.</p> <p>Results</p> <p>Patterns of gene expression in females and males reveal that 50% of assayed transcripts show some degree of sex-bias. Female-biased transcription is enriched for translation, metabolic and regulatory genes associated with development. Male-biased expression is enriched for cuticle and protease function. Comparison with well studied arthropods such as <it>Drosophila melanogaster </it>and <it>Anopheles gambiae </it>suggests that female-biased patterns tend to be conserved, whereas male-biased genes are evolving faster in <it>D. pulex</it>. These findings are based on the proportion of female-biased, male-biased, and unbiased genes that share sequence similarity with proteins in other animal genomes.</p> <p>Conclusion</p> <p>Some transcriptional differences between males and females appear to be conserved across Arthropoda, including the rapid evolution of male-biased genes which is observed in insects and now in a crustacean. Yet, novel patterns of male-biased gene expression are also uncovered. This study is an important first step towards a detailed understanding of the genetic basis and evolution of parthenogenesis, environmental sex determination, and adaptation to aquatic environments.</p

Thin film transistors fabricated by in-situ doped unhydrogenated polysilicon films obtained by solid phase crystallization

International audienceHigh mobility low temperature (≤ 600°C) unhydrogenated in-situ doped polysilicon thin film transistors are made. Polysilicon layers are grown by a LPCVD technique and crystallized in vacuum by a thermal annealing. Source and drain regions are in-situ doped. Gate insulator is made of an APCVD silicon dioxide. Hydrogen passivation is not performed on the transistors. One type of transistors is made of two polysilicon layers, the other one is constituted of a single polysilicon layer. The electrical properties are better for transistors made of single polysilicon layer: a low threshold voltage (1.2 V), a subthreshold slope S = 0.7 V/dec, a high field effect mobility (≈ 100 cm2/Vs) and a On/Off state current ratio higher than 107 for a drain voltage Vds = 1 V. At low drain voltage, for both transistors, the Off state current results from a pure thermal emission of trapped carriers. However, at high drain voltage, the electrical behavior is different: in the case of single polysilicon TFTs, the current obeys the field-assisted (Poole-Frenkel) thermal emission model of trapped carriers while for TFTs made of two polysilicon layers, the higher Off state current results from a field-enhanced thermal emission

A bipartite class of entanglement monotones for N-qubit pure states

We construct a class of algebraic invariants for N-qubit pure states based on bipartite decompositions of the system. We show that they are entanglement monotones, and that they differ from the well know linear entropies of the sub-systems. They therefore capture new information on the non-local properties of multipartite systems.Comment: 6 page

STEREO database of interplanetary Langmuir electric waveforms

International audienceThis paper describes a database of electric waveforms that is available at the Centre de Données de la Physique des Plasmas (CDPP, http://cdpp.eu/). This database is specifically dedicated to waveforms of Langmuir/Z-mode waves. These waves occur in numerous kinetic processes involving electrons in space plasmas. Statistical analysis from a large data set of such waves is then of interest, e.g., to study the relaxation of high-velocity electron beams generated at interplanetary shock fronts, in current sheets and magnetic reconnection region, the transfer of energy between high and low frequencies, the generation of electromagnetic waves. The Langmuir waveforms were recorded by the Time Domain Sampler (TDS) of the WAVES radio instrument on board the STEREO mission. In this paper, we detail the criteria used to identify the Langmuir/Z-mode waves among the whole set of waveforms of the STEREO spacecraft. A database covering the November 2006 to August 2014 period is provided. It includes electric waveforms expressed in the normalized frame inline image with B and Vsw the local magnetic field and solar wind velocity vectors, and the local magnetic field in the variance frame, in an interval of ±1.5 min around the time of the Langmuir event. Quicklooks are also provided that display the three components of the electric waveforms together with the spectrum of E∥, together with the magnitude and components of the magnetic field in the 3 min interval, in the variance frame. Finally, the distribution of the Langmuir/Z-mode waves peak amplitude is also analyzed