29,138 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
The National Pension System and Financial Consumers: An International Comparative Perspective on the Key Linkages
No full textA secure and adequate pension system is central to establish a welfare state. Given that, this book aims to document a set of diverse public policy issues on the financial consumers’ standpoint that are observed in different countries. In this introductiory chapter, we attempt to summarize those policy issues that emerged from the survey of the countries included with respect to each f the three dimensions – adequacy, coverage, and sustainability
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
Site-selective enzymatic C‒H amidation for synthesis of diverse lactams
No full textPlease note that this work has been retracted by the authors.After publication of the Report “Site-selective enzymatic C‒H amidation for synthesis of diverse lactams” in Science (1, also linked in metadata), efforts to reproduce the work showed that the enzymes do not catalyze the reactions with the activities and selectivities claimed. Careful examination of the first author’s lab notebook then revealed missing contemporaneous entries and raw data for key experiments. The authors therefore have retracted the article from Science and are now retracting the preprint from ChemRxiv. The original paper can be accessed by selecting “Version 1” of the preprint below, or by accessing https://doi.org/10.26434/chemrxiv.7711418.v1. Inha Cho, Zhi-Jun Jia, Frances H. Arnold*Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125, USA.*Corresponding author. Email: [email protected]. I. Cho, Z.-J. Jia, F. H. Arnold, Science 364, 575 (2019). DOI: 10.1126/science.aaw9068*******************************************************************************************Directed evolution of cytochrome P450 enzymes fine-tunes site selectivity of new-to-nature C‒H amidation for modular, sustainable and scalable preparation of enantio-enriched β-, γ- and δ-lactams.</p
On the Performance of Band-Limited Asynchronous DS-CDMA over Nakagami-m Channels
No full textIn this paper we investigated the BER performance of DS-CDMA using various chip-waveforms, which include three time-limited chip-waveforms and two band-limited chipwaveforms. Closed-form formulae were derived for evaluating the achievable bit-error rate performance with the aid of the standard Gaussian approximation, when communicating over a Nakagami-m channel. The time-limited waveforms impose a low implementational complexity, since they maybe oversampled and read from a look-up table. However, they are outperformed by the frequency-domain raised-cosine waveform as well as the optimum waveform specifically designed by Cho and Lehnert for achieving the lowest possible bit error rate. Index Terms—Code-division multiple-access, chip waveform, Gaussian approximation, Nakagami, band-limited, normalized bandwidth
Measurement of Plasma Presheath
No full textThe plasma presheath in a multidipole device was measured by an emissive probe using the inflection-point method in the limit of zero emission. The temporal evolution of ion-acoustic waves was also measured. Results are compared. It is shown that the potential in the bulk of the plasma is describable by a simplified version of the plasma-sheath equation. Inclusion of finite ion temperature has a negligible effect on the predicted results compared to the inclusion of the primary electrons in the theory.11Nsciescopu
Performance of microdot detectors of 50-, 100-, and 200-mu m pitches based on the amorphous silicon process
No full textMicrodot detectors, which are based on the amorphous silicon process and which have square-shaped electrodes and three different anode-to-anode distances of 50, 100, and 200 mum, have been developed for a reliable true two-dimensional (or pixel) device. Their electrical characteristics, such as insensitive regions and spatial resolution, were tested using a collimated X-ray beam as a probe. Our results suggest that the 100-mum pitch appears to be the optimum value both to minimize the defocusing away from the anode dots of the primary electrons and to achieve good spatial resolution (55 mum) and a moderate gas gain (3100)
Aeroelastic Stability of a Hingeless Rotor Blade in Hover Using Finite Elements Based on Large Deflection Theory
No full textAcute milk-based protein–CHO supplementation attenuates exercise-induced muscle damage
No full textExercise-induced muscle damage (EIMD) leads to the degradation of protein structures within the muscle. This may subsequently lead to decrements in muscle performance and increases in intramuscular enzymes and delayed-onset muscle soreness (DOMS). Milk, which provides protein and carbohydrate (CHO), may lead to the attenuation of protein degradation and (or) an increase in protein synthesis that would limit the consequential effects of EIMD. This study examined the effects of acute milk and milk-based protein–CHO (CHO-P) supplementation on attenuating EIMD. Four independent groups of 6 healthy males consumed water (CON), CHO sports drink, milk-based CHO-P or milk (M), post EIMD. DOMS, isokinetic muscle performance, creatine kinase (CK), and myoglobin (Mb) were assessed immediately before and 24 and 48 h after EIMD. DOMS was not significantly different (p > 0.05) between groups at any time point. Peak torque (dominant) was significantly higher (p < 0.05) 48 h after CHO-P compared with CHO and CON, and M compared with CHO. Total work of the set (dominant) was significantly higher (p < 0.05) 48 h after CHO-P and M compared with CHO and CON. CK was significantly lower (p < 0.05) 48 h after CHO-P and M compared with CHO. Mb was significantly lower (p < 0.05) 48 h after CHO-P compared with CHO. At 48 h post-EIMD, milk and milk-based protein–CHO supplementation resulted in the attenuation of decreases in isokinetic muscle performance and increases in CK and Mb
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