66,434 research outputs found
Unimodality of Betti numbers for Hamiltonian circle actions with index-increasing moment Maps
No full textThe unimodality conjecture posed by Tolman in [L. Jeffrey, T. Holm, Y. Karshon, E. Lerman and E. Meinrenken, Moment maps in various geometries, http://www.birs.ca/workshops/2005/05w5072/report05w5072.pdf] states that if (M,ω) is a 2n-dimensional smooth compact symplectic manifold equipped with a Hamiltonian circle action with only isolated fixed points, then the sequence of Betti numbers {b0(M),b2(M),...,b2n(M)} is unimodal, i.e. bi(M) ≤ bi+2(M) for every i < n. Recently, the author and Kim [Y. Cho and M. Kim, Unimodality of the Betti numbers for Hamiltonian circle action with isolated fixed points, Math. Res. Lett. 21(4) (2014) 691-696] proved that the unimodality holds in eight-dimensional case by using equivariant cohomology theory. In this paper, we generalize the idea in [Y. Cho and M. Kim, Unimodality of the Betti numbers for Hamiltonian circle action with isolated fixed points, Math. Res. Lett. 21(4) (2014) 691-696] to an arbitrary dimensional case. We prove the conjecture in arbitrary dimension under the assumption that the moment map H : M → R is index-increasing, which means that ind(p) < ind(q) implies H(p) < H(q) for every pair of critical points p and q of H, where ind(p) is the Morse index of p with respect to H. © World Scientific Publishing Company1111sciescopu
CHO microRNA engineering is growing up : recent successes and future challenges
No full textmicroRNAs with their ability to regulate complex pathways that control cellular behavior and phenotype have been proposed as potential targets for cell engineering in the context of optimization of biopharmaceutical production cell lines, specifically of Chinese Hamster Ovary cells. However, until recently, research was limited by a lack of genomic sequence information on this industrially important cell line. With the publication of the genomic sequence and other relevant data sets for CHO cells since 2011, the doors have been opened for an improved understanding of CHO cell physiology and for the development of the necessary tools for novel engineering strategies. In the present review we discuss both knowledge on the regulatory mechanisms of microRNAs obtained from other biological models and proof of concepts already performed on CHO cells, thus providing an outlook of potential applications of microRNA engineering in production cell lines
Dataset for Lasting effects of discontinuous shear thickening in cornstarch suspensions upon flow cessation
No full textThis dataset supports the publication: 'Lasting effects of discontinuous shear thickening in cornstarch suspensions upon flow cessation' by Jae Hyung Cho, Andrew H. Griese, Ivo Peters and Irmgard Bischofberger, Physical Review Fluids (2022) The data is in .xlsx format accessible in excel.
The file contains data to reproduce the following figures:
Fig 1. Flow curves
Fig 3. Temporal change in stresses and shear rate
Fig 4. Characteristic times
Fig 5. Transition times, scale parameter T, stress at transition, and residual stress
Fig 7. Transition mean normal stress
The data in the file is organized by figure, with a separate sheet for each figure containing the data to reproduce the respective figure</span
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
The ALMA-PILS survey: First detection of the unsaturated 3-carbon molecules Propenal (CHCHO) and Propylene (CH) towards IRAS 162932422 B
No full textAccepted for publication in A&A. 24 pages, 17 figuresInternational audienceComplex organic molecules with three carbon atoms are found in the earliest stages of star formation. In particular, propenal (CHCHO) is a species of interest due to its implication in the formation of more complex species and even biotic molecules. This study aims to search for the presence of CHCHO and other three-carbon species such as propylene (CH) in the hot corino region of the low-mass protostellar binary IRAS 16293--2422 to understand their formation pathways. We use ALMA observations in Band 6 and 7 from various surveys to search for the presence of CH and CHCHO towards the protostar IRAS 16293--2422 B (IRAS 16293B). We report the detection of both CH and CHCHO towards IRAS 16293B, however, no unblended lines were found towards the other component of the binary system, IRAS 16293A. We derive column density upper limits for CH, HCCCHO, n-CHOH, i-CHOH, CO, and cis-HC(O)CHO towards IRAS 16293B. We then use a three-phase chemical model to simulate the formation of these species in a typical prestellar environment followed by its hydrodynamical collapse until the birth of the central protostar. Different formation paths, such as successive hydrogenation and radical-radical additions on grain surfaces, are tested and compared to the observational results. The simulations reproduce the abundances within one order of magnitude from those observed towards IRAS 16293B, with the best agreement found for a rate of cm s for the gas-phase reaction C + O C + CO. Successive hydrogenations of C, HC(O)CHO, and CHOCHO on grain surfaces are a major and crucial formation route of complex organics molecules, whereas both successive hydrogenation pathways and radical-radical addition reactions contribute to the formation of CHCHO
Four-week inhalation toxicity, mutagenicity and immunotoxicity studies of Keum-Yeon-Cho (NosmoQ), tobacco substitute composition, in mice
No full textSafety of Kcum-Yeon-Cho (NosmoQ), a tobacco substitute composition, was evaluated in terms of acute- and 4,weeks repeated-inhalation toxicity, mutagenicity, and immunotoxicity using Balb/e mice. The air inside the inhalation chamber was collected and analyzed by GC-MS. In acute inhalation toxicity test, male and female mice were exposed to 40 Keum-Yeon-Cho cigarettes, The 50% lethal concentration (LC50) of NosmoQ was considered to be much higher than 40 cigarettes in both sexes. In 4-week repeated inhalation toxicity test, male and female mice were exposed for 6 h/day, 5 days/week for 4 weeks to 10 and 20 cigarettes per day, while control mice ere exposed to Filtered air. Our data indicated that no observed adverse effect level (NOAEL) of Keuna-Yeon-Cho should be over 20 cigarettes per day. Results of Salmonella typhimarium reversion assay with/without histidine moiety, in vivo chromosomal aberration and in vivo micronucleus assays using mouse bone marrow cells revealed that Kcum-Yeon-Cho has 110 mutagenicity. Evaluation of peripheral cellular immunity of mice treated with Keum-yeong-Cho using in vitro lymphocyte proliferation assay showed no significant difference in mean stimulation index (SI) between mice exposed to Keum-Yeon-Cho and control mice. Mean CO concentrations and total particulate matter contents of 10 and 20 cigarettes were 21.1 +/- 1.23 and 40.7 +/- 1.21 ppm (mean +/-S.D.. it = 5). and 25.7+/-3.09 and 59.0+/-4.0 mg dry weight (mean +/-S.D., n = 5), respectively. Although at negligible concentration (less than ppb level) several polycyclic aromatic hydrocarbons (PAHs) were also detected, these results indicate that NosmoQ has no toxic effect on mice. (C) 2002 Elsevier Science B.V. All rights reserved.N
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Enhanced embryonic stem cell differentiation to cardiac pacemaker cells by transduction with a single transcription factor
No full text
Cerebral oxygen metabolism from MRI susceptibility
No full textThis article provides an overview of MRI methods exploiting magnetic susceptibility properties of blood to assess cerebral oxygen metabolism, including the tissue oxygen extraction fraction (OEF) and the cerebral metabolic rate of oxygen (CMRO2). The first section is devoted to describing blood magnetic susceptibility and its effect on the MRI signal. Blood circulating in the vasculature can have diamagnetic (oxyhemoglobin) or paramagnetic properties (deoxyhemoglobin). The overall balance between oxygenated and deoxygenated hemoglobin determines the induced magnetic field which, in turn, modulates the transverse relaxation decay of the MRI signal via additional phase accumulation. The following sections of this review then illustrate the principles underpinning susceptibility-based techniques for quantifying OEF and CMRO2. Here, it is detailed whether these techniques provide global (OxFlow) or local (Quantitative Susceptibility Mapping - QSM, calibrated BOLD - cBOLD, quantitative BOLD - qBOLD, QSM+qBOLD) measurements of OEF or CMRO2, and what signal components (magnitude or phase) and tissue pools they consider (intravascular or extravascular). Validations studies and potential limitations of each method are also described. The latter include (but are not limited to) challenges in the experimental setup, the accuracy of signal modeling, and assumptions on the measured signal. The last section outlines the clinical uses of these techniques in healthy aging and neurodegenerative diseases and contextualizes these reports relative to results from gold-standard PET
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