20,313 research outputs found

    Computer Simulations of Cosmic Reionization

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    The cosmic reionization of hydrogen was the last major phase transition in the evolution of the universe, which drastically changed the ionization and thermal conditions in the cosmic gas. To the best of our knowledge today, this process was driven by the ultra-violet radiation from young, star-forming galaxies and from first quasars. We review the current observational constraints on cosmic reionization, as well as the dominant physical effects that control the ionization of intergalactic gas. We then focus on numerical modeling of this process with computer simulations. Over the past decade, significant progress has been made in solving the radiative transfer of ionizing photons from many sources through the highly inhomogeneous distribution of cosmic gas in the expanding universe. With modern simulations, we have finally converged on a general picture for the reionization process, but many unsolved problems still remain in this young and exciting field of numerical cosmology.Comment: Invited Review to appear on Advanced Science Letters (ASL), Special Issue on Computational Astrophysics, edited by Lucio Maye

    Epigenomic views of innate lymphoid cells

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    The discovery of innate lymphoid cells (ILCs) with selective production of cytokines typically attributed to subsets of T helper cells forces immunologists to reassess the mechanisms by which selective effector functions arise. The parallelism between ILCs and T cells extends beyond these two cell types and comprises other innate-like T lymphocytes. Beyond the recognition of specialized effector functionalities in diverse lymphocytes, features typical of T cells, such as plasticity and memory, are also relevant for innate lymphocytes. Herein, we review what we have learned in terms of the molecular mechanisms underlying these shared functions, focusing on insights provided by next generation sequencing technologies. We review data on the role of lineage-defining- and signal-dependent transcription factors (TFs). ILC regulomes emerge developmentally whereas the much of the open chromatin regions of T cells are generated acutely, in an activation-dependent manner. And yet, these regions of open chromatin in T cells and ILCs have remarkable overlaps, suggesting that though accessibility is acquired by distinct modes, the end result is that convergent signaling pathways may be involved. Although much is left to be learned, substantial progress has been made in understanding how TFs and epigenomic status contribute to ILC biology in terms of differentiation, specification, and plasticity

    collected from South and South-eastern regions of Turkey

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    A total of 45 lizards (Acanthodactylus harranensis [n = 15], Acanthodacthylus schreiberi [n = 9] and Mesalina brevirostris [n = 21]) were collected from South and Southeastern Regions of Turkey and examined for helminth fauna. Acanthodactylus harranensis harbored 1 species of Nematoda (Skrjabinodon sp.), 1 species of Cestoda (Oochoristica tuberculata) and 1 species of Acanthocephala (Centrorhynchus sp. [cystacanth]). Acanthodactylus schreiberi harbored unidentified cysticercoids. Mesalina brevirostris harbored 1 species of Nematoda (Spauligodon saxicolae). All lizards represents new host records for the helminths reported in this study

    Nonclassicality of photon-added squeezed vacuum and its decoherence in thermal environment

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    We study the nonclassicality of photon-added squeezed vacuum (PASV) and its decoherence in thermal environment in terms of the sub-Poissonian statistics and the negativity of Wigner function (WF). By converting the PASV to a squeezed Hermite polynomial excitation state, we derive a compact expression for the normalization factor of m-PASV, which is an m-order Legendre polynomial of squeezing parameter r. We also derive the explicit expression of WF of m-PASV and find the negative region of WF in phase space. We show that there is an upper bound value of r for this state to exhibit sub-Poissonian statistics increasing as m increases. Then we derive the explicit analytical expression of time evolution of WF of m-PASV in the thermal channel and discuss the loss of nonclassicality using the negativity of WF. The threshold value of decay time is presented for the single PASV.Comment: 14 pages and 7 figure

    Field distribution of epidural electrical stimulation

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    Epidural electrical stimulation has been applied in clinics for many years. However, there is still a concern about possible injury to spinal nerves. This study investigated electrical field and current density distribution during direct epidural electrical stimulation. Field distribution models were theoretically deduced, while the distribution of potentials and current were analyzed. The current density presented an increase of 70-80%, with one peak value ranging from -85 degrees to 85 degrees between the two stimulated poles. The effect of direct epidural electrical stimulation is mainly on local tissue surrounding the electrodes, concentrated around the two stimulated positions.postprin

    A dynamic prediction model for intraoperative somatosensory evoked potential monitoring

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    This study proposed a support vector regression model applied in prediction of intraoperative somatosensory evoked potential changes associated with physiological and anesthetic changes. This model was developed from probability distribution and support vector machines. The predicted results showed that observed and predicted SEP has similar variation trend with different values, with acceptable errors. With this prediction model, changes of SEP in correlation with non-surgical factors were estimated. Not only the prediction accuracy of SEP has been improved, but also provides the reliability of the classification. It will be helpful to develop an intelligent monitor model based expert system that can make a reliable decision for the potential spinal injury.published_or_final_versio

    Dialogic Reading With Attention-Deficit-Hyperactivity Disorder (ADHD) Kindergarteners: Does Reading With Parents or Siblings Enhance Their Language Development?

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    Dialogic reading (DR) is an interactive reading approach that enhances the language development of children. This study aims to extend DR to the shared reading context involving children with attentiondeficit-hyperactivity disorder (ADHD) and their older siblings and to examine the effects of DR with parents/siblings on the language development of Chinese children with ADHD. This study included 850 Chinese kindergarteners with ADHD and their parents/older siblings. These children were pretested on their Chinese receptive vocabulary, expressive vocabulary, character reading, listening comprehension, and reading interest and were randomly assigned to four groups, namely, dialogic reading with parents (PR-DR), dialogic reading with siblings (SR-DR), parent reading control (PR-C), and sibling reading control (SR-C). After a 12-week intervention period, they were posttested on the same measures. Results show that both DR with parents and siblings effectively enhanced language skills and reading interest in children with ADHD. In addition, those children who read with their older siblings demonstrated greater improvements in their expressive vocabulary, character reading skills, morphological awareness, phonological awareness, and reading interest yet achieved a smaller growth in their listening comprehension compared with those who read with their parents. These findings showed the positive effects of DR on the language development of children with ADHD and highlight the importance of involving siblings in home literacy activities to facilitate the language development of these children

    Narrowband Single-Pole Double-Throw Filtering Switch Based on Dielectric Resonator

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    © 2001-2012 IEEE. In this letter, a narrowband single-pole double-throw (SPDT) filtering switch based on dielectric resonators (DRs) is presented. It consists of two DRs shared by two channels for size reduction. Printed circuit boards are embedded in the metal cavity to integrate the PIN diodes. The switching between two channels is enabled by controlling the PIN diodes connected to the two output feeding lines. The electromagnetic field distributions of the DR at the TE -{11\delta } mode are studied to control the coupling between the DR and two output feeding lines. When one channel is on, the PIN diode for this channel is turned off, which does not introduce loss and affect the linearity. For the off-state channel, isolation is obtained by controlling the coupling between the DR and output feeding line, which is considerably enhanced. For demonstration, the DR filtering SPDT switch is implemented. The measured results exhibit that the proposed filtering SPDT switch has narrow bandwidth, low loss, high isolation, and high linearity
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