66,603 research outputs found
Conversion of a gastric band into an intraperitoneal port in a patient with optimally debulked stage 3C serous ovarian carcinoma
Intraperitoneal (IP) chemotherapy in women with optimally debulked stage 3 ovarian cancer improves overall survival and progression-free survival, and its use has been encouraged in the adjuvant treatment of appropriately selected patients (Armstrong et al., 2006; Jaaback and Johnson, 2006). We describe a case in which a previously inserted adjustable gastric band was converted to an IP chemotherapy port during a laparotomy for advanced ovarian cancer
Effects of Latent Heating on Atmospheres of Brown Dwarfs and Directly Imaged Planets
Growing observations of brown dwarfs have provided evidence for strong
atmospheric circulation on these objects. Directly imaged planets share similar
observations, and can be viewed as low-gravity versions of brown dwarfs.
Vigorous condensate cycles of chemical species in their atmospheres are
inferred by observations and theoretical studies, and latent heating associated
with condensation is expected to be important in shaping atmospheric
circulation and influencing cloud patchiness. We present a qualitative
description of the mechanisms by which condensational latent heating influence
the circulation, and then illustrate them using an idealized general
circulation model that includes a condensation cycle of silicates with latent
heating and molecular weight effect due to rainout of condensate. Simulations
with conditions appropriate for typical T dwarfs exhibit the development of
localized storms and east-west jets. The storms are spatially inhomogeneous,
evolving on timescale of hours to days and extending vertically from the
condensation level to the tropopause. The fractional area of the brown dwarf
covered by active storms is small. Based on a simple analytic model, we
quantitatively explain the area fraction of moist plumes, and show its
dependence on radiative timescale and convective available potential energy. We
predict that, if latent heating dominates cloud formation processes, the
fractional coverage area by clouds decreases as the spectral type goes through
the L/T transition from high to lower effective temperature. This is a natural
consequence of the variation of radiative timescale and convective available
potential energy with spectral type.Comment: 13 pages, 8 figures, accepted for publication in Ap
Can the Japan-Philippines Economic Partnership Agreement (JPEPA) Benefit Philippine Consumer Goods Exporters?
Why has the Philippines not been getting a larger slice of the Japanese market as compared with other ASEAN countries and with China? What factors prevent it from this? Can the talks on the Japan-Philippines Economic Partnership Agreement (JPEPA) help address these concerns? This Policy Notes dwells on these issues as it examines the opportunities and constraints for Philippine consumer goods exports in the Japanese market and in the areas where the JPEPA may help.small and medium enterprises, bilateral agreements, Japan-Philippines economic partnership, consumer goods exports
On the Formation of Runaway Stars BN and x in the Orion Nebula Cluster
We explore scenarios for the dynamical ejection of stars BN and x from source
I in the Kleinmann-Low nebula of the Orion Nebula Cluster (ONC), which is
important for being the closest region of massive star formation. This ejection
would cause source I to become a close binary or a merger product of two stars.
We thus consider binary-binary encounters as the mechanism to produce this
event. By running a large suite of -body simulations, we find that it is
nearly impossible to match the observations when using the commonly adopted
masses for the participants, especially a source I mass of .
The only way to recreate the event is if source I is more massive, i.e.,
. However, even in this case, the likelihood of
reproducing the observed system is low. We discuss the implications of these
results for understanding this important star-forming region.Comment: 7 pages, 4 figures, 1 table. Accepted by A&A Letter
MEG sensor and source measures of visually induced gamma-band oscillations are highly reliable
High frequency brain oscillations are associated with numerous cognitive and behavioral processes. Non-invasive measurements using electro-/magnetoencephalography (EEG/MEG) have revealed that high frequency neural signals are heritable and manifest changes with age as well as in neuropsychiatric illnesses. Despite the extensive use of EEG/MEG-measured neural oscillations in basic and clinical research, studies demonstrating test–retest reliability of power and frequency measures of neural signals remain scarce. Here, we evaluated the test–retest reliability of visually induced gamma (30–100 Hz) oscillations derived from sensor and source signals acquired over two MEG sessions. The study required participants (N = 13) to detect the randomly occurring stimulus acceleration while viewing a moving concentric grating. Sensor and source MEG measures of gamma-band activity yielded comparably strong reliability (average intraclass correlation, ICC = 0.861). Peak stimulus-induced gamma frequency (53–72 Hz) yielded the highest measures of stability (ICCsensor = 0.940; ICCsource = 0.966) followed by spectral signal change (ICCsensor = 0.890; ICCsource = 0.893) and peak frequency bandwidth (ICCsensor = 0.856; ICCsource = 0.622). Furthermore, source-reconstruction significantly improved signal-to-noise for spectral amplitude of gamma activity compared to sensor estimates. Our assessments highlight that both sensor and source derived estimates of visually induced gamma-band oscillations from MEG signals are characterized by high test–retest reliability, with source derived oscillatory measures conferring an improvement in the stability of peak-frequency estimates. Importantly, our finding of high test–retest reliability supports the feasibility of pharma-MEG studies and longitudinal aging or clinical studies
When is Eaton's Markov chain irreducible?
Consider a parametric statistical model and an
improper prior distribution that together yield a
(proper) formal posterior distribution . The prior is
called strongly admissible if the generalized Bayes estimator of every bounded
function of is admissible under squared error loss. Eaton [Ann.
Statist. 20 (1992) 1147--1179] has shown that a sufficient condition for strong
admissibility of is the local recurrence of the Markov chain whose
transition function is . Applications of this result and its
extensions are often greatly simplified when the Markov chain associated with
is irreducible. However, establishing irreducibility can be difficult. In
this paper, we provide a characterization of irreducibility for general state
space Markov chains and use this characterization to develop an easily checked,
necessary and sufficient condition for irreducibility of Eaton's Markov chain.
All that is required to check this condition is a simple examination of and
. Application of the main result is illustrated using two examples.Comment: Published at http://dx.doi.org/10.3150/07-BEJ6191 in the Bernoulli
(http://isi.cbs.nl/bernoulli/) by the International Statistical
Institute/Bernoulli Society (http://isi.cbs.nl/BS/bshome.htm
Atmospheric Circulation of Brown Dwarfs and Jupiter and Saturn-like Planets: Zonal Jets, Long-term Variability, and QBO-type Oscillations
Brown dwarfs and directly imaged giant planets exhibit significant evidence
for active atmospheric circulation, which induces a large-scale patchiness in
the cloud structure that evolves significantly over time, as evidenced by
infrared light curves and Doppler maps. These observations raise critical
questions about the fundamental nature of the circulation, its time
variability, and the overall relationship to the circulation on Jupiter and
Saturn. Jupiter and Saturn themselves exhibit numerous robust zonal (east-west)
jet streams at the cloud level; moreover, both planets exhibit long-term
stratospheric oscillations involving perturbations of zonal wind and
temperature that propagate downward over time on timescales of ~4 years
(Jupiter) and ~15 years (Saturn). These oscillations, dubbed the Quasi
Quadrennial Oscillation (QQO) for Jupiter and the Semi-Annual Oscillation (SAO)
on Saturn, are thought to be analogous to the Quasi-Biennial Oscillation (QBO)
on Earth, which is driven by upward propagation of equatorial waves from the
troposphere. To investigate these issues, we here present global,
three-dimensional, high-resolution numerical simulations of the flow in the
stratified atmosphere--overlying the convective interior--of brown dwarfs and
Jupiter-like planets. The effect of interior convection is parameterized by
inducing small-scale, randomly varying perturbations in the
radiative-convective boundary at the base of the model. In the simulations, the
convective perturbations generate atmospheric waves and turbulence that
interact with the rotation to produce numerous zonal jets. Moreover, the
equatorial stratosphere exhibits stacked eastward and westward jets that
migrate downward over time, exactly as occurs in the terrestrial QBO, Jovian
QQO, and Saturnian SAO. This is the first demonstration of a QBO-like
phenomenon in 3D numerical simulations of a giant planet.Comment: 27 pages, 15 figures, in press at ApJ; this is the revised (accepted)
version, which includes a major new section providing detailed analysis of
the types of wave modes present in the model, and characterizing the
wave-mean-flow interactions by which they generate the QBO-like oscillation
Effects of Geometric Phases in Josephson Junction Arrays
We show that the en route vortex velocity dependent part of the Magnus force
in a Josephson junction array is effectively zero, and predict zero Hall effect
in the classical limit. However, geometric phases due to the finite superfluid
density at superconductor grains have a profound influence on the quantum
dynamics of vortices. Subsequently we find rich and complex Hall behaviors
analogous to the Thouless-Kohmoto-Nightingale-den Nijs effect in the quantum
regime.Comment: Latex, 11 pages, appeared in Phys. Rev. Lett. v.77, 562 (1996) with
minor change
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