Effect of feeding different levels of corn snack waste on broiler performance

This study was conducted to investigate the effect of using corn snack waste on growth performance, carcass traits and economical efficiency of broiler chicks. Five hundred Ross 308 day-old broiler chicks were divided randomly into 20 pens. There were 25 chicks in each pen which consists of 4 treatments (4 levels of waste corn snack) with five  replicates. Corn snack waste had been considered in grower and finisher periods in level 170, 300 and 500 g/Kg of diet. Usage of corn snack waste had reduced (P<0.05) feed intake and weight gain of broiler chicks. However usage of corn snack waste in broiler chick's diet in levels 170 and 350 g/Kg increased feed conversion ratio and in level  500 g/Kg, feed conversion ratio were improved (p<0.05). The usage of corn snack waste was induced by the negative effect on performance of carcass and weight thigh, but reduced breast meat weight also reduces  abdominal fat, and had no effect on liver, heart, gastrointestinal tract (p<0.05).Keyword: Corn snack waste, corn by-product, broiler performance, broiler diet

Searching for the most powerful thermonuclear X-ray bursts with the Neil Gehrels Swift Observatory

We searched for thermonuclear X-ray bursts from Galactic neutron stars in all event mode data of the Neil Gehrels Swift Observatory collected until March 31, 2018. In particular, we are interested in the intermediate-duration bursts (shell flashes fueled by thick helium piles) with the ill-understood phenomenon of strong flux fluctuations. Nine such bursts have been discussed in the literature to date. Swift is particularly suitable for finding additional examples. We find and list a total of 134 X-ray bursts; 44 are detected with BAT only, 41 with XRT only, and 49 with both. Twenty-eight bursts involve automatic slews. We find 12 intermediate-duration bursts, all detected in observations involving automatic slews. Five show remarkably long Eddington-limited phases in excess of 200 s. Five show fluctuations during the decay phase; four of which are first discussed in the present study. We discuss the general properties of the fluctuations, considering also 7 literature cases. In general two types of fluctuations are observed: fast ones, with a typical timescale of 1 s and up and downward fluctuations of up to 70%, and slow ones, with a typical timescale of 1 min and only downward fluctuations of up to 90%. The latter look like partial eclipses because the burst decay remains visible in the residual emission. We revisit the interpretation of this phenomenon in the context of the new data set and find that it has not changed fundamentally despite the expanded data set. It is thought to be due to a disturbance of the accretion disk by outflowing matter and photons, causing obscuration and reflection due to Thompson scattering in an orbiting highly ionized cloud or structure above or below the disk. We discuss in detail the most pronounced burster SAX J1712.6-3739. One of the bursts from this source is unusual in that it lasts longer than 5600 s, but does not appear to be a superburst.Comment: Accepted for publication in Astronomy & Astrophysics, 29 pages, 12 figures. Version 2 has 3 bursts from IGR J17480-2446 re-identified to 2 from Swift J174805.3-244637 and 1 from EXO 1745-24

IGR J17254-3257, a new bursting neutron star

The study of the observational properties of uncommonly long bursts from low luminosity sources with extended decay times up to several tens of minutes is important when investigating the transition from a hydrogen-rich bursting regime to a pure helium regime and from helium burning to carbon burning as predicted by current burst theories. IGR J17254-3257 is a recently discovered X-ray burster of which only two bursts have been recorded: an ordinary short type I X-ray burst, and a 15 min long burst. An upper limit to its distance is estimated to about 14.5 kpc. The broad-band spectrum of the persistent emission in the 0.3-100 keV energy band obtained using contemporaneous INTEGRAL and XMM-Newton data indicates a bolometric flux of 1.1x10^-10 erg/cm2/s corresponding, at the canonical distance of 8 kpc, to a luminosity about 8.4x10^35 erg/s between 0.1-100 keV, which translates to a mean accretion rate of about 7x10^-11 solar masses per year. The low X-ray persistent luminosity of IGR J17254-3257 seems to indicate the source may be in a state of low accretion rate usually associated with a hard spectrum in the X-ray range. The nuclear burning regime may be intermediate between pure He and mixed H/He burning. The long burst is the result of the accumulation of a thick He layer, while the short one is a prematurate H-triggered He burning burst at a slightly lower accretion rate.Comment: 4 pages, 4 figures, 1 table; accepted for publication in A&A Letters. 1 reference (Cooper & Narayan, 2007) correcte

Evidence of heavy-element ashes in thermonuclear X-ray bursts with photospheric superexpansion

A small subset of thermonuclear X-ray bursts on neutron stars exhibit such a strong photospheric expansion that for a few seconds the photosphere is located at a radius r_ph >~ 1000 km. Such `superexpansions' imply a large and rapid energy release, a feature characteristic of pure He burst models. Previous calculations have shown that during a pure He burst, the freshly synthesized heavy-element ashes of burning can be ejected in a strong radiative wind and produce significant spectral absorption features. We search the burst data catalogs and literature and find 32 superexpansion bursts. We find that these bursts exhibit the following interesting features: (1) At least 31 are from (candidate) ultracompact X-ray binaries in which the neutron star accretes hydrogen-deficient fuel, suggesting that these bursts indeed ignite in a helium-rich layer. (2) In 2 bursts we detect strong absorption edges during the expansion phase. The edge energies and depths are consistent with the H-like or He-like edge of iron-peak elements with abundances greater than 100 times solar, suggesting that we are seeing the exposed ashes of nuclear burning. (3) The superexpansion phase is always followed by a moderate expansion phase during which r_ph ~ 30 km and the luminosity is near the Eddington limit. (4) The decay time of the bursts, t_d, ranges from short (approximately 10 s) to intermediate (>~ 1000 s). However, despite the large range of t_d, the duration of the superexpansion is always a few seconds, independent of t_d. By contrast, the duration of the moderate expansion is always of order t_d. (5) The photospheric radii r_ph during the moderate expansion phase are much smaller than steady state wind models predict. We show that this may be further indication that the wind contains highly non-solar abundances of heavy elements.Comment: Accepted for publication in Astronomy & Astrophysic

Broad-band X-ray measurements of the black hole candidate XTE J1908+094

XTE J1908+094 is an X-ray transient that went into outburst in February 2002. After two months it reached a 2-250 keV peak flux of 1 to 2 X 10-8 erg/s/cm2. Circumstantial evidence points to an accreting galactic black hole as the origin of the the X-radiation: pulsations nor thermonuclear flashes were detected that would identify a neutron star and the spectrum was unusually hard for a neutron star at the outburst onset. We report on BeppoSAX and RXTE All Sky Monitor observations of the broad-band spectrum of XTE J1908+094. The spectrum is consistent with a model consisting of a Comptonization component by a ~40 keV plasma (between 2 and 60 keV this component can be approximated by a power law with a photon index of 1.9 to 2.1), a multicolor accretion disk blackbody component with a temperature just below 1 keV and a broad emission line at about 6 keV. The spectrum is heavily absorbed by cold interstellar matter with an equivalent hydrogen column density of 2.5 X 10+22 cm-2, which makes it difficult to study the black body component in detail. The black body component exhibits strong evolution about 6 weeks into the outburst. Two weeks later this is followed by a swift decay of the power law component. The broadness of the 6 keV feature may be due to relativistic broadening or Compton scattering of a narrow Fe-K line.Comment: Accepted for publication in Astronomy & Astrophysic

A four-year baseline Swift study of enigmatic X-ray transients located near the Galactic center

We report on continued monitoring observations of the Galactic center carried out by the X-ray telescope aboard the Swift satellite in 2008 and 2009. This campaign revealed activity of the five known X-ray transients AX J1745.6-2901, CXOGC J174535.5-290124, GRS 1741-2853, XMM J174457-2850.3 and CXOGC J174538.0-290022. All these sources are known to undergo very faint X-ray outbursts with 2-10 keV peak luminosities of Lx,peak~1E34-1E36 erg/s, although the two confirmed neutron star low-mass X-ray binaries AX J1745.6-2901 and GRS 1741-2853 can also become brighter (Lx,peak~1E36-1E37 erg/s). We discuss the observed long-term lightcurves and X-ray spectra of these five enigmatic transients. In 2008, AX J1745.6-2901 returned to quiescence following an unusually long accretion outburst of more than 1.5 years. GRS 1741-2853 was active in 2009 and displayed the brightest outburst ever recorded for this source, reaching up to a 2-10 keV luminosity of Lx~1E37 (D/7.2 kpc)^2 erg/s. This system appears to undergo recurrent accretion outbursts approximately every 2 years. Furthermore, we find that the unclassified transient XMM J174457-2850.3 becomes bright only during short episodes (days) and is often found active in between quiescence (Lx~1E32 erg/s) and its maximum outburst luminosity of Lx~1E36 erg/s. CXOGC J174535.5-290124 and CXOGC J174538.0-290022, as well as three other very-faint X-ray transients that were detected by Swift monitoring observations in 2006, have very low time-averaged mass-accretion rates of ~< 2E-12 Msun/yr. Despite having obtained two years of new data in 2008 and 2009, no new X-ray transients were detected.Comment: Minor textual revisions according to referee report, accepted for publication in A&

The effect of rotation on the stability of nuclear burning in accreting neutron stars

Hydrogen and/or helium accreted by a neutron star from a binary companion may undergo thermonuclear fusion. At different mass accretion rates different burning regimes are discerned. Theoretical models predict helium fusion to proceed as a thermonuclear runaway for accretion rates below the Eddington limit and as stable burning above this limit. Observations, however, place the boundary close to 10% of the Eddington limit. We study the effect of rotationally induced transport processes on the stability of helium burning. For the first time detailed calculations of thin helium shell burning on neutron stars are performed using a hydrodynamic stellar evolution code including rotation and rotationally induced magnetic fields. We find that in most cases the instabilities from the magnetic field provide the dominant contribution to the chemical mixing, while Eddington-Sweet circulations become important at high rotation rates. As helium is diffused to greater depths, the stability of the burning is increased, such that the critical accretion rate for stable helium burning is found to be lower. Combined with a higher heat flux from the crust, as suggested by recent studies, turbulent mixing could explain the observed critical accretion rate. Furthermore, close to this boundary we find oscillatory burning, which previous studies have linked to mHz QPOs. In models where we continuously lower the heat flux from the crust, the period of the oscillations increases by up to several tens of percents, similar to the observed frequency drift, suggesting that this drift could be caused by the cooling of deeper layers.Comment: 11 pages, 11 figures, accepted for publication in Astronomy and Astrophysic

Discovery of the INTEGRAL X/Gamma-ray transient IGR J00291+5934: a Comptonised accreting ms pulsar ?

We report the discovery of a high-energy transient with the IBIS/ISGRI detector on board the INTEGRAL observatory. The source, namely IGR J00291+5934, was first detected on 2nd December 2004 in the routine monitoring of the IBIS/ISGRI 20--60 keV images. The observations were conducted during Galactic Plane Scans, which are a key part of the INTEGRAL Core Programme observations. After verifying the basic source behaviour, the discovery was announced on 3rd December. The transient shows a hard Comptonised spectrum, with peak energy release at about 20 keV and a total luminosity of ~ 0.9E36 erg/s in the 5--100 keV range, assuming a distance of 3 kpc. Following the INTEGRAL announcement of the discovery of IGR J00291+5934, a number of observations were made by other instruments. We summarise the results of those observations and, together with the INTEGRAL data, identifiy IGR J00291+5934 as the 6th member of a class of accreting X-ray millisecond pulsars.Comment: Accepted for publication as an A&A Letter 24/01/2005. 5 pages, 2 figure

Chandra and RXTE Spectra of the Burster GS 1826-238

Using simultaneous observations from Chandra and RXTE, we investigated the LMXB GS 1826-238 with the goal of studying its spectral and timing properties. The uninterrupted Chandra observation captured 6 bursts (RXTE saw 3 of the 6), yielding a recurrence time of 3.54 +/- 0.03 hr. Using the proportional counter array on board RXTE, we made a probable detection of 611 Hz burst oscillations in the decaying phases of the bursts with an average rms signal amplitude of 4.8%. The integrated persistent emission spectrum can be described as the dual Comptonization of ~ 0.3 keV soft photons by a plasma with kT_e ~ 20 keV and an optical depth of about 2.6 (interpreted as emission from the accretion disk corona), plus the Comptonization of hotter ~ 0.8 keV seed photons by a ~ 6.8 keV plasma (interpreted as emission from or near the boundary layer). We discovered evidence for a neutral Fe K\alpha emission line, and we found interstellar Fe L_II and Fe L_III absorption features. The burst spectrum can be fit by fixing the disk Comptonization parameters to the persistent emission best-fit values, and adding a blackbody. The blackbody/seed photon temperature at the peak of the burst is ~ 1.8 keV and returns to ~ 0.8 keV over 200 s. The blackbody radius is consistent with R_bb = 10.3-11.7 km assuming a distance of 6 kpc; however, by accounting for the fraction of the surface that is obscured by the disk as a function of binary inclination, we determined the source distance must actually be near 5 kpc in order for the stellar radius to lie within the commonly assumed range of 10-12 km.Comment: Accepted for publication in ApJ; 13 pages, 6 figure