9,391 research outputs found
Guidelines for the Provision of Garbage Reception Facilities at Ports Under MARPOL Annex V
This report offers guidelines for the provision of adequate
port reception facilities for vessel-generated garbage
under the requirements of Annex V of the International
Convention for the Prevention of Pollution From Ships, 1973 (MARPOL 73/78), Regulations for the Prevention of Pollution by Garbage from Ships. MARPOL Annex V prohibits at-sea disposal of plastic materials from vessels, and specifies the distance from shore at which other materials may be dumped. Annex V also requires the provision of port reception facilities for garbage, but it does not specify these facilities or how they are to be provided. Since the at-sea dumping restrictions apply to all vessels, the reception facility requirement applies to all ports, terminals, and marinas that serve vessels. These guidelines were prepared to assist port owners and operators in meeting their obligation to provide adequate reception facilities for garbage. The report synthesizes available information and draws upon experience from the first years ofimplementation of MARPOL Annex V. (PDF file contains 55 pages.
Catalogue of Be/X-ray binary systems in the Small Magellanic Cloud: X-ray, optical & IR properties
This is a catalogue of approximately 70 X-ray emitting binary systems in the
Small Magellanic Cloud (SMC) that contain a Be star as the mass donor in the
system and a clear X-ray pulse signature from a neutron star. The systems are
generally referred to as Be/Xray binaries. It lists all their known binary
characteristics (orbital period, eccentricity), the measured spin period of the
compact object, plus the characteristics of the Be star (spectral type, size of
the circumstellar disk, evidence for NRP behaviour). For the first time data
from the Spitzer Observatory are combined with ground-based data to provide a
view of these systems out into the far-IR. Many of the observational parameters
are presented as statistical distributions and compared to other similar
similar populations (eg isolated Be & B stars) in the SMC, and to other
Be/X-ray systems in the Milky Way. In addition previous important results are
re-investigated using this excellently homogeneous sample. In particular, the
evidence for a bi-modality in the spin period distribution is shown to be even
stronger than first proposed, and the correlation between orbital period and
circumstellar disk size seen in galactic sources is shown to be clearly present
in the SMC systems and quantised for the first time.Comment: 10 pages, 10 figures, 4 tables. Accepted for publication in MNRA
OGLE observations of four X-ray binary pulsars in the SMC
This paper presents analysis and interpretation of OGLE photometric data of
four X-ray binary pulsar systems in the Small Magellanic Cloud: 1WGA
J0054.9-7226, RX J0050.7-7316, RX J0049.1-7250, and 1SAX J0103.2-7209. In each
case, the probable optical counterpart is identified on the basis of its
optical colours. In the case of RX J0050.7-7316 the regular modulation of its
optical light curve appears to reveal an ellipsoidal modulation with a period
of 1.416 days. Using reasonable masses for the neutron star and the B star, we
show that the amplitude and relative depths of the minima of the I-band light
curve of RX J0050.7-7316 can be matched with an ellipsoidal model where the B
star nearly fills its Roche lobe. For mass ratios in the range of 0.12 to 0.20,
the corresponding best-fitting inclinations are about 55 degrees or larger. The
neutron star would be eclipsed by the B star at inclinations larger than 60
degrees for this particular mass ratio range. Thus RX J0050.7-7316 is a good
candidate system for further study. In particular, we would need additional
photometry in several colours, and most importantly, radial velocity data for
the B star before we could draw more quantitative conclusions about the
component masses
Characterizing a configuration interaction excited state using natural transition geminals
We introduce natural transition geminals as a means to qualitatively
understand a transition where double excitations are important. The first two
singlet states of the CH cation are used as an initial example. We
calculate these states with configuration interaction singles (CIS) and
state-averaged Monte Carlo configuration interaction (SA-MCCI). For each method
we compare the important natural transition geminals with the dominant natural
transition orbitals. We then compare SA-MCCI and full configuration interaction
(FCI) with regards to the natural transition geminals using the beryllium atom.
We compare using the natural transition geminals with analyzing the important
configurations in the CI expansion to give the dominant transition for the
beryllium atom and the carbon dimer. Finally we calculate the natural
transition geminals for two electronic excitations of formamide.Comment: 15 pages, 2 figures. Mol. Phys. (2013
Approaching exact hyperpolarizabilities via sum-over-states Monte Carlo configuration interaction
We propose using sum-over-states calculations with the compact wavefunctions
of Monte Carlo configuration interaction to approach accurate values for
higher-order dipole properties up to second hyperpolarizabilities in a
controlled way. We apply the approach to small systems that can generally be
compared with full configuration interaction (FCI) results. We consider
hydrogen fluoride with a 6-31g basis and then look at results, including
frequency dependent properties, in an aug-cc-pVDZ basis. We extend one
calculation beyond FCI by using an aug-cc-pVTZ basis. The properties of an
H molecule with multireference character are calculated in an aug-cc-pVDZ
basis. We then investigate this method on a strongly multireference system with
a larger FCI space by modelling the properties of carbon monoxide with a
stretched geometry. The behavior of the approach with increasing basis size is
considered by calculating results for the neon atom using aug-cc-pVDZ to
aug-cc-pVQZ. We finally test if the unusual change in polarizability between
the first two states of molecular oxygen can be reproduced by this method in a
6-31g basis.Comment: 11 pages, 14 figure
SXP 323 - an unusual X-ray binary system in the Small Magellanic Cloud
Spectroscopic observations taken with the VLT/UVES telescope/instrument are
presented of the unusual Small Magellanic Cloud (SMC) X-ray binary system SXP
323 = AX J0051-733. This system shows a clear modulation at 0.71d in long term
optical photometry which has been proposed as the binary period of this system.
The high resolution optical spectra, taken at a range of phases during the
0.71d cycle, rule out this possibility. Instead it is suggested that this
long-term effect is due to Non Radial Pulsations (NRP) in the Be star companion
to SXP 323. In addition, the spectra show clear evidence for major changes in
the (V/R) ratio of the double peaks of the Balmer lines indicative of
asymmetries in the circumstellar disk. The complex structure of the
interstellar lines are also discussed in the context of the SMC structure.Comment: Accepted in MNRA
Applying Monte Carlo configuration interaction to transition metal dimers: exploring the balance between static and dynamic correlation
We calculate potential curves for transition metal dimers using Monte Carlo
configuration interaction (MCCI). These results, and their associated
spectroscopic values, are compared with experimental and computational studies.
The multireference nature of the MCCI wavefunction is quantified and we
estimate the important orbitals. We initially consider the ground state of the
chromium dimer. Next we calculate potential curves for Sc where we
contrast the lowest triplet and quintet states. We look at the molybdenum dimer
where we compare non-relativistic results with the partial inclusion of
relativistic effects via effective core potentials, and report results for
scandium nickel.Comment: 9 pages and 8 figure
A major outburst from the X-ray binary RX J0520.5-6932
We report on the analysis of 8 years of MAssive Compact Halo Objects (MACHO)
data for the source RX J0520.5-6932. A regular period of 24.4 days has been
confirmed, however this is manifest almost entirely in the red part of the
spectrum. A major outburst, lasting approximately 200 days, was observed which
increased the apparent brightness of the object by approximately 0.15
magnitudes without significantly altering its V-R colour index. This outburst
was also seen in X-ray data. The evidence from this analysis points to the
identification of this object as a Be/X-ray binary with a periodically variable
circumstellar disk and a very early optical counterpart.Comment: Paper has been accepted by MNRA
Monte Carlo configuration interaction applied to multipole moments, ionisation energies and electron affinities
The method of Monte Carlo configuration interaction (MCCI) [1,2] is applied
to the calculation of multipole moments. We look at the ground and excited
state dipole moments in carbon monoxide. We then consider the dipole of NO, the
quadrupole of the nitrogen molecule and of BH. An octupole of methane is also
calculated. We consider experimental geometries and also stretched bonds. We
show that these non-variational quantities may be found to relatively good
accuracy when compared with FCI results, yet using only a small fraction of the
full configuration interaction space. MCCI results in the aug-cc-pVDZ basis are
seen to generally have reasonably good agreement with experiment. We also
investigate the performance of MCCI when applied to ionisation energies and
electron affinities of atoms in an aug-cc-pVQZ basis. We compare the MCCI
results with full configuration-interaction quantum Monte Carlo [3,4] and
`exact' non-relativistic results [3,4]. We show that MCCI could be a useful
alternative for the calculation of atomic ionisation energies however electron
affinities appear much more challenging for MCCI. Due to the small magnitude of
the electron affinities their percentage errors can be high, but with regards
to absolute errors MCCI performs similarly for ionisation energies and electron
affinities.Comment: 12 pages, 20 figure
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