XMM-Newton EPIC and OM observation of Nova Centauri 1986 (V842 Cen)

We report the results from the temporal and spectral analysis of an XMM-Newton observation of Nova Centauri 1986 (V842 Cen). We detect a period at 3.51$\pm$0.4 h in the EPIC data and at 4.0$\pm$0.8 h in the OM data. The X-ray spectrum is consistent with the emission from an absorbed thin thermal plasma with a temperature distribution given by an isobaric cooling flow. The maximum temperature of the cooling flow model is $kT_{max}=43_{-12}^{+23}$ keV. Such a high temperature can be reached in a shocked region and, given the periodicity detected, most likely arises in a magnetically-channelled accretion flow characteristic of intermediate polars. The pulsed fraction of the 3.51 h modulation decreases with energy as observed in the X-ray light curves of magnetic CVs, possibly due either to occultation of the accretion column by the white dwarf body or phase-dependent to absorption. We do not find the 57 s white dwarf spin period, with a pulse amplitude of 4 mmag, reported by Woudt et al. (2009) either in the Optical Monitor (OM) data, which are sensitive to pulse amplitudes $\gtrsim$ 0.03 magnitudes, or the EPIC data, sensitive to pulse fractions $p \gtrsim$ 14 $\pm$2%.Comment: 5 pages, 3 figures; MNRAS, accepte

Water, land and carbon footprints of Chinese dairy in the past and future

Chinese food consumption shifts towards larger milk consumption. Traditional dairy systems depended on China's grasslands, but modern industrial systems using feed from croplands increase rapidly. The question is whether China can fulfill future milk demand using its natural resources and remain within greenhouse gas emission boundaries. To determine this, this study combines three footprint analyses - water footprint (WF), land footprint (LF) and carbon footprint (CF) - estimated via production chain approach. It compares WFs, LFs and CFs of milk, meat, and manure from six dairy systems in three categories: traditional grazing, traditional mixed, and modern industrial systems. It estimates future footprints for five production scenarios for low and high milk demand. Between 2000 and 2020, industrial systems increased, accounting for 79 % of production in 2020, while traditional production decreased. Traditional grazing systems have large green WFs per kg (17.2 m3), negligible blue WFs and large LFs (46 m2 low quality grassland). Traditional mixed systems have large CFs per kg (2.93 kg CO2) due to low efficiency. Modern industrial systems rely partly on irrigated croplands and have small green WFs, but large blue WFs per kg (0.54 m3), grey WFs (0.24 m3) and small LFs (1.80 m2 cropland). The findings indicate that with dominating industrial systems, milk production relies more on irrigation and limited croplands. In a realistic low demand situation, milk consumption stabilizes. However, consumption triples if the Chinese follow nutritional advice, resulting in 4 to 6 times larger WFs, LFs and CFs in 2035 depending on production scenarios. In 2035, population is largest, from 2035 to 2050 footprints decrease again. However, China cannot produce the milk for a high consumption situation limited by grassland and cropland availability. Alternatively, China could import feed or milk. However, it is questionable whether these huge quantities are available on the global market.</p

Effect of electroacupuncture (EA) on gastrointestinal peristaltism in dogs

The article has no abstract

Scattering Angles in Kerr Metrics

Scattering angles for probes in Kerr metrics are derived for scattering in the equatorial plane of the black hole. We use a method that naturally resums all orders in the spin of the Kerr black hole, thus facilitating comparisons with scattering-angle computations based on the Post-Minkowskian expansion from scattering amplitudes or worldline calculations. We extend these results to spinning black-hole probes up to and including second order in the probe spin and any order in the Post- Minkowskian expansion, for probe spins aligned with the Kerr spin. When truncating to third Post-Minkowskian order, our results agree with those obtained by amplitude and worldline methods

A multi-wavelength study of star formation activity in the S235 complex

We have carried out an extensive multi-wavelength study to investigate the star formation process in the S235 complex. The S235 complex has a sphere-like shell appearance at wavelengths longer than 2 $\mu$m and harbors an O9.5V type star approximately at its center. Near-infrared extinction map traces eight subregions (having A$_{V}$ $>$ 8 mag), and five of them appear to be distributed in an almost regularly spaced manner along the sphere-like shell surrounding the ionized emission. This picture is also supported by the integrated $^{12}$CO and $^{13}$CO intensity maps and by Bolocam 1.1 mm continuum emission. The position-velocity analysis of CO reveals an almost semi-ring like structure, suggesting an expanding H\,{\sc ii} region. We find that the Bolocam clump masses increase as we move away from the location of the ionizing star. This correlation is seen only for those clumps which are distributed near the edges of the shell. Photometric analysis reveals 435 young stellar objects (YSOs), 59\% of which are found in clusters. Six subregions (including five located near the edges of the shell) are very well correlated with the dust clumps, CO gas, and YSOs. The average values of Mach numbers derived using NH$_{3}$ data for three (East~1, East~2, and Central~E) out of these six subregions are 2.9, 2.3, and 2.9, indicating these subregions are supersonic. The molecular outflows are detected in these three subregions, further confirming the on-going star formation activity. Together, all these results are interpreted as observational evidence of positive feedback of a massive star.Comment: 28 pages, 15 figures, 3 tables, Accepted for publication in The Astrophysical Journa

Increasing activity in T CrB suggests nova eruption is impending

Estimates of the accretion rate in symbiotic recurrent novae (RNe) often fall short of theoretical expectations by orders of magnitude. This apparent discrepancy can be resolved if the accumulation of mass by the white dwarf (WD) is highly sporadic, and most observations are performed during low states. Here we use a reanalysis of archival data from the Digital Access to a Sky Century @Harvard (DASCH) survey to argue that the most recent nova eruption in symbiotic RN T CrB, in 1946, occurred during -- and was therefore triggered by -- a transient accretion high state. Based on similarities in the optical light curve around 1946 and the time of the prior eruption, in 1866, we suggest that the WD in T CrB accumulates most of the fuel needed to ignite the thermonuclear runaways (TNRs) during accretion high states. A natural origin for such states is dwarf-nova like accretion-disk instabilities, which are expected in the presumably large disks in symbiotic binaries. The timing of the TNRs in symbiotic RNe could thus be set by the stability properties of their accretion disks. T CrB is in the midst of an accretion high state like the ones we posit led to the past two nova eruptions. Combined with the approach of the time at which a TNR would be expected based on the 80-year interval between the prior two novae ($2026 \pm$3), the current accretion high state increases the likelihood of a TNR occurring in T CrB in the next few years.Comment: Accepted in ApJ

Riddled-like Basin in Two-Dimensional Map for Bouncing Motion of an Inelastic Particle on a Vibrating Board

Motivated by bouncing motion of an inelastic particle on a vibrating board, a simple two-dimensional map is constructed and its behavior is studied numerically. In addition to the typical route to chaos through a periodic doubling bifurcation, we found peculiar behavior in the parameter region where two stable periodic attractors coexist. A typical orbit in the region goes through chaotic motion for an extended transient period before it converges into one of the two periodic attractors. The basin structure in this parameter region is almost riddling and the fractal dimension of the basin boundary is close to two, {\it i.e.}, the dimension of the phase space.Comment: 4 pages, 5 figures. to be published in J. Phys. Soc. Jpn. (2002