2,592 research outputs found
Quantitative Implementation of Acoustic Impedance Inversion to Porosity and Lithology Prediction of Clastic Reservoir, Luhais Oil Field, Southern Iraq
In the present study, some of petrophysical properties of Nuhr Umr Formation in Luhais oil field (south of Iraq) are evaluated by using an acoustic impedance inversion process. 2D seismic reflection data of (29) lines covering the field, neutron porosity logs, and synthetic acoustic impedance logs were used in inversion of seismic sections into an acoustic impedance and porosity sections. To compensate the low frequency in relative acoustic impedance that rely on seismic data frequency (band-limit frequency), we inverted relative acoustic impedance with combination the low frequency of well data to obtain absolute acoustic impedance. The absolute acoustic impedance shows consistency and good tie with an acoustic impedance log. At the reservoir interval the lithology was discriminate and evaluate the facies quality of Nahr-Umr Formation using absolute acoustic impedance inversion and subdivided into three main members. The shale facies indicate high porosity (25%) corresponding to low acoustic impedance (6500 Kpa. m/s) at the top of the reservoir. The petrophysical analysis declare and confirm higher quality reservoir is noticed and recognized in the middle member of Nahr-Umr reservoir. Keywords: seismic inversion, porosity prediction, Absolute Acoustic impedanc
Probing the Magnetized Interstellar Medium Surrounding the Planetary Nebula Sh 2-216
We present 1420 MHz polarization images of a 2.5 X 2.5 degree region around
the planetary nebula (PN) Sh 2-216. The images are taken from the Canadian
Galactic Plane Survey (CGPS). An arc of low polarized intensity appears
prominently in the north-east portion of the visible disk of Sh 2-216,
coincident with the optically identified interaction region between the PN and
the interstellar medium (ISM). The arc contains structural variations down to
the ~1 arcminute resolution limit in both polarized intensity and polarization
angle. Several polarization-angle "knots" appear along the arc. By comparison
of the polarization angles at the centers of the knots and the mean
polarization angle outside Sh 2-216, we estimate the rotation measure (RM)
through the knots to be -43 +/- 10 rad/m^2. Using this estimate for the RM and
an estimate of the electron density in the shell of Sh 2-216, we derive a
line-of-sight magnetic field in the interaction region of 5.0 +/- 2.0 microG.
We believe it more likely the observed magnetic field is interstellar than
stellar, though we cannot completely dismiss the latter possibility. We
interpret our observations via a simple model which describes the ISM magnetic
field around Sh 2-216, and comment on the potential use of old PNe as probes of
the magnetized ISM.Comment: 25 pages, 4 figures. Accepted for publication in the Astrophysical
Journa
Rates of species introduction to a remote oceanic island
The introduction of species to areas beyond the limits of their natural distributions has a major homogenizing influence, making previously distinct biotas more similar. The scale of introductions has frequently been commented on, but their rate and spatial pervasiveness have been less well quantified. Here, we report the findings of a detailed study of pterygote insect introductions to Gough Island, one of the most remote and supposedly pristine temperate oceanic islands, and estimate the rate at which introduced species have successfully established.
Out of 99 species recorded from Gough Island, 71 are established introductions, the highest proportion documented for any Southern Ocean island. Estimating a total of approximately 233 landings on Gough Island since first human landfall, this equates to one successful establishment for every three to four landings. Generalizations drawn from other areas suggest that this may be only one-tenth of the number of pterygote species that have arrived at the island, implying that most landings may lead to the arrival of at least one alien. These rates of introduction of new species are estimated to be two to three orders of magnitude greater than background levels for Gough Island, an increase comparable to that estimated for global species extinctions (many of which occur on islands) as a consequence of human activities
The use of oral recombinant feline interferon omega in two cats with type II diabetes mellitus and concurrent feline chronic gingivostomatitis syndrome
Articles in International JournalsFeline Chronic Gingivostomatitis Syndrome (FCGS) is a common disease in clinical practice. Among the therapeutic
options available, long-acting corticosteroids are frequently used due to their anti-inflammatory and
immunosuppressive properties. Although they may improve the clinical symptoms, they can lead to a progressive
form of the disease that becomes refractory to treatment. Furthermore, their direct relationship with type II diabetes
mellitus (DM) is well known. Consequently, these drugs are controversial and not recommended for routine
management of FCGS. Recombinant feline interferon-omega (rFeIFN-ω) is an immunomodulatory compound.
Recently, its daily oral administration has been shown to be successful in treating refractory cases of FCGS. This case
study describes two clinical cases of type II DM complicated by FCGS. Both animals were calicivirus positive and
they had been previously treated with long-acting corticosteroids, which may have been the major cause of DM.
The two cats were treated with glargine insulin (Lantus, starting dose 1 IU/cat twice daily (BID)), achieving remission
10 and 18 weeks later respectively. Considering the difficulty with control of FCGS in these animals, an oral daily
dose of rFeIFN-ω was started as an alternative to long-acting corticosteroids. In both cats oral clinical signs
gradually improved and 60 days after the start of therapy the owners reported a significant relief of pain during
mastication. According to the authors’ knowledge, this is the first case report that describes the successful use of
rFeIFN-ω in the management of FCGS in type II diabetic cats, in which long-acting corticosteroids are
contraindicated
Near-field interactions between metal nanoparticle surface plasmons and molecular excitons in thin-films: part I: absorption
In this and the following paper (parts I and II, respectively), we systematically study the interactions between surface plasmons of metal nanoparticles (NPs) with excitons in thin-films of organic media. In an effort to exclusively probe near-field interactions, we utilize spherical Ag NPs in a size-regime where far-field light scattering is negligibly small compared to absorption. In part I, we discuss the effect of the presence of these Ag NPs on the absorption of the embedding medium by means of experiment, numerical simulations, and analytical calculations, all shown to be in good agreement. We observe absorption enhancement in the embedding medium due to the Ag NPs with a strong dependence on the medium permittivity, the spectral position relative to the surface plasmon resonance frequency, and the thickness of the organic layer. By introducing a low index spacer layer between the NPs and the organic medium, this absorption enhancement is experimentally confirmed to be a near field effect In part II, we probe the impact of the Ag NPs on the emission of organic molecules by time-resolved and steady-state photoluminescence measurements
Breakdown of Conformal Invariance at Strongly Random Critical Points
We consider the breakdown of conformal and scale invariance in random systems
with strongly random critical points. Extending previous results on
one-dimensional systems, we provide an example of a three-dimensional system
which has a strongly random critical point. The average correlation functions
of this system demonstrate a breakdown of conformal invariance, while the
typical correlation functions demonstrate a breakdown of scale invariance. The
breakdown of conformal invariance is due to the vanishing of the correlation
functions at the infinite disorder fixed point, causing the critical
correlation functions to be controlled by a dangerously irrelevant operator
describing the approach to the fixed point. We relate the computation of
average correlation functions to a problem of persistence in the RG flow.Comment: 9 page
Parallax of PSR J1744-1134 and the Local Interstellar Medium
We present the annual trigonometric parallax of PSR J1744-1134 derived from
an analysis of pulse times of arrival. The measured parallax, pi = 2.8+/-0.3
mas ranks among the most precisely determined distances to any pulsar. The
parallax distance of 357+/-39 pc is over twice that derived from the dispersion
measure using the Taylor & Cordes model for the Galactic electron distribution.
The mean electron density in the path to the pulsar, n_e = (0.0088 +/- 0.0009)
cm^{-3}, is the lowest for any disk pulsar. We have compared the n_e for PSR
J1744-1134 with those for another 11 nearby pulsars with independent distance
estimates. We conclude that there is a striking asymmetry in the distribution
of electrons in the local interstellar medium. The electron column densities
for pulsars in the third Galactic quadrant are found to be systematically
higher than for those in the first. The former correlate with the position of
the well known local HI cavity in quadrant three. The excess electrons within
the cavity may be in the form of HII clouds marking a region of interaction
between the local hot bubble and a nearby superbubble.Comment: revised version accepted for publication in ApJ Letters; reanalysis
of uncertainty in parallax measure and changes to fig
The motion of the 2D hydrodynamic Chaplygin sleigh in the presence of circulation
We consider the motion of a planar rigid body in a potential flow with
circulation and subject to a certain nonholonomic constraint. This model is
related to the design of underwater vehicles.
The equations of motion admit a reduction to a 2-dimensional nonlinear
system, which is integrated explicitly. We show that the reduced system
comprises both asymptotic and periodic dynamics separated by a critical value
of the energy, and give a complete classification of types of the motion. Then
we describe the whole variety of the trajectories of the body on the plane.Comment: 25 pages, 7 figures. This article uses some introductory material
from arXiv:1109.321
Drivers and outcomes of work alienation: reviving a concept
This article sheds new light on an understudied construct in mainstream management theory, namely, work alienation.
This is an important area of study because previous research indicates that work alienation is associated with important
individual and organizational outcomes. We tested four antecedents of work alienation: decision-making autonomy, task
variety, task identity, and social support. Moreover, we examined two outcomes of alienation: deviance and performance, the
former measured 1 year after the independent variables were measured, and the latter as rated by supervisors. We present
evidence from a sample of 283 employees employed at a construction and consultancy organization in the United Kingdom.
The results supported the majority of our hypotheses, indicating that alienation is a worthy concept of exploration in the
management sciences
Beam-Breakup Instability Theory for Energy Recovery Linacs
Here we will derive the general theory of the beam-breakup instability in
recirculating linear accelerators, in which the bunches do not have to be at
the same RF phase during each recirculation turn. This is important for the
description of energy recovery linacs (ERLs) where bunches are recirculated at
a decelerating phase of the RF wave and for other recirculator arrangements
where different RF phases are of an advantage. Furthermore it can be used for
the analysis of phase errors of recirculated bunches. It is shown how the
threshold current for a given linac can be computed and a remarkable agreement
with tracking data is demonstrated. The general formulas are then analyzed for
several analytically solvable cases, which show: (a) Why different higher order
modes (HOM) in one cavity do not couple so that the most dangerous modes can be
considered individually. (b) How different HOM frequencies have to be in order
to consider them separately. (c) That no optics can cause the HOMs of two
cavities to cancel. (d) How an optics can avoid the addition of the
instabilities of two cavities. (e) How a HOM in a multiple-turn recirculator
interferes with itself. Furthermore, a simple method to compute the orbit
deviations produced by cavity misalignments has also been introduced. It is
shown that the BBU instability always occurs before the orbit excursion becomes
very large.Comment: 12 pages, 6 figure
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