Mode Change of a Gamma-Ray Pulsar, PSR J2021+4026

Zhao, J.,Ng, C. W.,Lin, L. C. C.,Takata, J.,Cai, Y.,Hu, C.-P.,Yen, D. C. C.,Tam, P. H. T.,Hui, C. Y.,Kong, A. K. H.,Cheng, K. S. American Astronomical Society 2017 The Astrophysical journal Vol.842 No.1

<P>A glitch of a pulsar is known as a sudden increase in the spin frequency and spin-down rate (frequency time derivative), and it can be caused by a sudden release of the stress built up in the solid crust of the star or pinned vortices in the superfluid interior. PSR J2021+4026 is the first pulsar that shows a significant change in the gamma-ray flux and pulse profile at the glitch that occurred around 2011 October 16. We report the results of timing and spectral analysis of PSR J2021+4026 using similar to 8 yr Fermi. Large Area Telescope data. We find that the pulsar stayed at a high spin-down rate (similar to 4% higher than the pre-glitch value) and a low gamma-ray state (similar to 18% lower) for about 3 yr. after the glitch. Around 2014 December, the spin-down rate and gamma-ray flux gradually returned to pre-glitch values within a timescale of a. few months. The phase-resolved spectra and pulse profiles after the relaxation are also consistent with those before the glitch. The observed long-term evolution of the spin-down rate and the gamma-ray flux indicates that the glitch triggered a mode change in the global magnetosphere. We speculate that the glitch changed. the local magnetic field structure around the polar cap and/or the inclination angle of the. dipole axis, leading to. a change in the electric current circulating in the. magnetosphere.</P>

Effects of Tween 80 on In Vitro Fermentation of Silages and Interactive Effects of Tween 80, Monensin and Exogenous Fibrolytic Enzymes on Growth Performance by Feedlot Cattle

Wang, Y.,McAllister, T.A.,Baah, J.,Wilde, R.,Beauchemin, K.A.,Rode, L.M.,Shelford, J.A.,Kamande, G.M.,Cheng, K.J. Asian Australasian Association of Animal Productio 2003 Animal Bioscience Vol.16 No.7

The effects of monensin, Tween 80 and exogenous fibrolytic enzymes on ruminal fermentation and animal performance were studied in vitro and in vivo. In Expt 1, the effects of the surfactant Tween 80 (0.2% wt/wt, DM basis) on ruminal fermentation of alfalfa, corn and orchardgrass silages were investigated using in vitro gas production techniques. Tween 80 did not affect (p>0.05) cumulative gas production at 24 h, but it reduced (p<0.05) the lag in fermentation of all three silages. With corn silage and orchardgrass silage, gas production rates and concentrations of total volatile fatty acids (VFA) were increased (p<0.05) by Tween 80; with alfalfa silage, they were reduced (p<0.05). Tween 80 increased (p<0.05) the proportion of propionate in total VFA, and reduced (p<0.05) acetate to propionate ratios (A:P) with all three silages. In Expt 2, exogenous fibrolytic enzymes (E; at 0, 37.5 or 75 g/tonne DM), monensin (M; at 0 or 25 ppm and Tween 80 (T; at 0 or 2 L/tonne DM) were added alone or in combination to backgrounding and finishing diets fed to 320 crossbred steers in a feeding trial with a $3{\times}2{\times}$2 factorial arrangement of treatments. The backgrounding and finishing diets contained barley grain and barley silage in ratios of 57.8:42.2 and 93.5:6.5 (DM basis), respectively. Added alone, none of the additives affected DM intake (p>0.1) in the backgrounding or in the finishing period, but interactive $M{\times}T$ effects were observed in the finishing period (p=0.02) and overall (p=0.04). In the finishing period, T without M tended to reduce DM intake (p=0.11), but T with M increased (p=0.05) DM intake. Monensin increased average daily gain (ADG) during backgrounding (p=0.07) and finishing (p=0.01), and this ionophore also improved overall feed efficiency (p=0.02). Warm carcass weight was increased (p<0.001) by M, but dressing percentage was reduced (p=0.07). In the backgrounding period, T increased ADG by 7% (p=0.06). Enzymes increased (p=0.07) ADG by 5 and 6% (low and high application rates, respectively) during backgrounding, but did not affect (p>0.10) ADG during finishing, or overall feed efficiency. Whereas T enhanced the positive effects of M on ADG during backgrounding (p=0.04) and overall (p=0.05), it had no impact (p>0.1) on the effects of E. Interactions between M and T suggest that the surfactant may have potential for enhancing the positive effects of monensin on beef production, but this requires further research.

Overview of Cellulolytic Activity and Enzyme Characteristics of Ruminal Anaerobic Fungi

Lee, S. S 韓國酪農學會 1997 韓國酪農學會誌 Vol.19 No.1

Rapid X-Ray Variations of the Geminga Pulsar Wind Nebula

Hui, C. Y.,Lee, Jongsu,Kong, A. K. H.,Tam, P. H. T.,Takata, J.,Cheng, K. S.,Ryu, Dongsu American Astronomical Society 2017 The Astrophysical journal Vol.846 No.2

<P>A recent study by Posselt et al. reported the deepest X-ray investigation of the Geminga pulsar wind nebula (PWN) by using Chandra X-ray Observatory. In comparison with previous studies of this system, a number of new findings have been reported, and we found that these suggest the possible variabilities in various components of this PWN. This motivates us to carry out a dedicated search for the morphological and spectral variations of this complex nebula. We have discovered variabilities on timescales from a few days to a few months from different components of the nebula. The fastest change occurred in the circumstellar environment at a rate of 80% of the speed of light. One of the most spectacular results is the wiggling of a half light-year long tail as an extension of the jet, which is significantly bent by the ram pressure. The jet wiggling occurred at a rate of about 20% of the speed of light. This twisted structure could possibly be a result of a propagating torsional Alfv'en wave. We have also found evidence of spectral hardening along this tail for a period of about nine months.</P>

DISCOVERY OF AN UNIDENTIFIED <i>FERMI</i> OBJECT AS A BLACK WIDOW-LIKE MILLISECOND PULSAR

Kong, A. K. H.,Huang, R. H. H.,Cheng, K. S.,Takata, J.,Yatsu, Y.,Cheung, C. C.,Donato, D.,Lin, L. C. C.,Kataoka, J.,Takahashi, Y.,Maeda, K.,Hui, C. Y.,Tam, P. H. T. IOP Publishing 2012 ASTROPHYSICAL JOURNAL LETTERS - Vol.747 No.1

<P>The Fermi gamma-ray Space Telescope has revolutionized our knowledge of the gamma-ray pulsar population, leading to the discovery of almost 100 gamma-ray pulsars and dozens of gamma-ray millisecond pulsars (MSPs). Although the outer-gap model predicts different sites of emission for the radio and gamma-ray pulsars, until now all of the known gamma-ray MSPs have been visible in the radio. Here we report the discovery of a 'radio-quiet' gamma-ray-emitting MSP candidate by using Fermi, Chandra, Swift, and optical observations. The X-ray and gamma-ray properties of the source are consistent with known gamma-ray pulsars. We also found a 4.63 hr orbital period in optical and X-ray data. We suggest that the source is a black widow-like MSP with a similar to 0.1 M-circle dot late-type companion star. Based on the profile of the optical and X-ray light curves, the companion star is believed to be heated by the pulsar while the X-ray emissions originate from pulsar magnetosphere and/or from intrabinary shock. No radio detection of the source has been reported yet, and although no gamma-ray/radio pulsation has been found we estimate that the spin period of the MSP is similar to 3-5 ms based on the inferred gamma-ray luminosity.</P>

Histone deacetylase 11: A novel epigenetic regulator of myeloid derived suppressor cell expansion and function

Sahakian, E.,Powers, J.J.,Chen, J.,Deng, S.L.,Cheng, F.,Distler, A.,Woods, D.M.,Rock-Klotz, J.,Sodre, A.L.,Youn, J.I.,Woan, K.V.,Villagra, A.,Gabrilovich, D.,Sotomayor, E.M.,Pinilla-Ibarz, J. Pergamon Press 2015 Molecular immunology Vol.63 No.2

Myeloid-derived suppressor cells (MDSCs), a heterogeneous population of cells capable of suppressing anti-tumor T cell function in the tumor microenvironment, represent an imposing obstacle in the development of cancer immunotherapeutics. Thus, identifying elements essential to the development and perpetuation of these cells will undoubtedly improve our ability to circumvent their suppressive impact. HDAC11 has emerged as a key regulator of IL-10 gene expression in myeloid cells, suggesting that this may represent an important targetable axis through which to dampen MDSC formation. Using a murine transgenic reporter model system where eGFP expression is controlled by the HDAC11 promoter (Tg-HDAC11-eGFP), we provide evidence that HDAC11 appears to function as a negative regulator of MDSC expansion/function in vivo. MDSCs isolated from EL4 tumor-bearing Tg-HDAC11-eGFP display high expression of eGFP, indicative of HDAC11 transcriptional activation at steady state. In striking contrast, immature myeloid cells in tumor-bearing mice display a diminished eGFP expression, implying that the transition of IMC to MDSC's require a decrease in the expression of HDAC11, where we postulate that it acts as a gate-keeper of myeloid differentiation. Indeed, tumor-bearing HDAC11-knockout mice (HDAC11-KO) demonstrate a more suppressive MDSC population as compared to wild-type (WT) tumor-bearing control. Notably, the HDAC11-KO tumor-bearing mice exhibit enhanced tumor growth kinetics when compare to the WT control mice. Thus, through a better understanding of this previously unknown role of HDAC11 in MDSC expansion and function, rational development of targeted epigenetic modifiers may allow us to thwart a powerful barrier to efficacious immunotherapies.

SEARCH FOR PULSED γ-RAY EMISSION FROM GLOBULAR CLUSTER M28

Wu, J. H. K.,Hui, C. Y.,Wu, E. M. H.,Kong, A. K. H.,Huang, R. H. H.,Tam, P. H. T.,Takata, J.,Cheng, K. S. IOP Publishing 2013 ASTROPHYSICAL JOURNAL LETTERS - Vol.765 No.2

<P>Using the data from the Large Area Telescope on board the Fermi Gamma-ray Space Telescope, we have searched for gamma-ray pulsations from the direction of the globular cluster M28 (NGC 6626). We report the discovery of a signal with a frequency consistent with that of the energetic millisecond pulsar (MSP) PSR B1821-24 in M28. A weighted H-test test statistic of 28.8 is attained, which corresponds to a chance probability of similar to 10(-5) (4.3 sigma detection). With a phase-resolved analysis, the pulsed component is found to contribute similar to 25% of the total observed gamma-ray emission from the cluster. However, the unpulsed level provides a constraint for the underlying MSP population and the fundamental plane relations for the scenario of inverse Compton scattering. Follow-up timing observations in radio/X-ray are encouraged to further investigate this periodic signal candidate.</P>

High-energy Emissions from the Pulsar/Be Binary System PSR J2032+4127/MT91 213

Takata, J.,Tam, P. H. T.,Ng, C. W.,Li, K. L.,Kong, A. K. H.,Hui, C. Y.,Cheng, K. S. American Astronomical Society 2017 The Astrophysical journal Vol.836 No.2

<P>PSR. J2032+4127 is a radio-loud gamma-ray-emitting pulsar; it is orbiting around a high-mass Be type star with a very long orbital period of 25-50 years, and is approaching periastron, which will occur in late 2017/early 2018. This system comprises a young pulsar and a Be type star, which is similar to the so-called gamma-ray binary PSR. B1259-63/LS2883. It is expected therefore that PSR. J2032+4127 shows an enhancement of high-energy emission caused by the interaction between the pulsar wind and Be wind/disk around periastron. Ho et al. recently reported a rapid increase in the X-ray flux from this system. In this paper, we also confirm a rapid increase in the X-ray flux along the orbit, while the GeV flux shows no significant change. We discuss the high-energy emissions from the shock caused by the pulsar wind and stellar wind interaction and examine the properties of the pulsar wind in this binary system. We argue that the rate of increase of the X-ray flux observed by Swift indicates (1) a variation of the momentum ratio of the two-wind interaction region along the orbit, or (2) an evolution of the magnetization parameter of the pulsar wind with the radial distance from the pulsar. We also discuss the pulsar wind/Be disk interaction at the periastron passage, and propose the possibility of formation of an accretion disk around the pulsar. We model high-energy emissions through the inverse-Compton scattering process of the cold-relativistic pulsar wind off soft photons from the accretion disk.</P>

APMP international comparison of AC-DC transfer standards at the lowest attainable level of uncertainty

Budovsky, I.,Abidin, A.R.B.Z.,Yan, A.Y.K.,Liu, LingXiang,Rustagi, V.K.,Govil, A.K.,Klonz, M.,Wei, Yih-cheng,Early, M.D.,Sasaki, H.,Fujiki, H.,Kumtawee, C.,Charoensook, A.,Kwon, Sung-Won,Son, N.A.,Supr IEEE 2005 IEEE transactions on instrumentation and measureme Vol.54 No.2

This paper presents preliminary results of the APMP.EM-K6a key comparison of AC-DC transfer conducted during 2000 to 2003. The AC-DC voltage transfer difference of the travelling standard was measured at 3 V and selected frequencies from 1 kHz to 1 MHz that included those of the CCEM-K6a key comparison. Also discussed are the methods used to compare thermal voltage converters with different input connectors, and to link the results to the parent Consultative Committee on Electricity and Magnetism (CCEM) comparison.

THE ORIGIN OF GAMMA RAYS FROM GLOBULAR CLUSTERS

Cheng, K. S.,Chernyshov, D. O.,Dogiel, V. A.,Hui, C. Y.,Kong, A. K. H. IOP Publishing 2010 The Astrophysical journal Vol.723 No.2