1,199 research outputs found
An Approximate Method of Images for Finite and Non-Linear Boundaries
The method of images is used in many different modeling scenarios such as electrostatics, fluid mechanics, and groundwater flow modeling to create infinitely long linear boundaries, such as a no-flow boundary across which flux is zero. We are using the groundwater flow arena to experiment with creating an adapted method of images to model a finite length no-flow boundaries. This is applicable to real world scenarios such as groundwater flow near impermeable bedrock. Using MATLAB, as well as our own work by hand, we are attempting to create a process that allows us to model flow near finite straight and curved boundaries. The programming is still in preliminary stages so there are not yet conclusive results, but we anticipate being able to construct both straight and curved finite no-flow boundaries
Deletion mutants in COP9/Signalosome subunits in fission yeast Schizosaccharomyces pombe display distinct phenotypes
The COP9/signalosome complex is highly conserved in evolution and possesses significant structural similarity to the 19S regulatory lid complex of the proteasome. It also shares limited similarity to the translation initiation factor eIF3. The signalosome interacts with multiple cullins in mammalian cells. In the fission yeast Schizosaccharomyces pombe, the Csn1 subunit is required for the removal of covalently attached Nedd8 from Pcu1, one of three S. pombe cullins. It remains unclear whether this activity is required for all the functions ascribed to the signalosome. We previously identified Csn1 and Csn2 as signalosome subunits in S. pombe. csn1 and csn2 null mutants are DNA damage sensitive and exhibit slow DNA replication. Two further putative subunits, Csn4 and Csn5, were identified from the S. pombe genome database. Herein, we characterize null mutations of csn4 and csn5 and demonstrate that both genes are required for removal of Nedd8 from the S. pombe cullin Pcu1 and that their protein products associate with Csn1 and Csn2. However, neither csn4 nor csn5 null mutants share the csn1 and csn2 mutant phenotypes. Our data suggest that the subunits of the signalosome cannot be considered as a distinct functional unit and imply that different subunits of the signalosome mediate distinct functions
A table of elliptic curves over the cubic field of discriminant -23
Let F be the cubic field of discriminant -23 and O its ring of integers. Let
Gamma be the arithmetic group GL_2 (O), and for any ideal n subset O let
Gamma_0 (n) be the congruence subgroup of level n. In a previous paper, two of
us (PG and DY) computed the cohomology of various Gamma_0 (n), along with the
action of the Hecke operators. The goal of that paper was to test the
modularity of elliptic curves over F. In the present paper, we complement and
extend this prior work in two ways. First, we tabulate more elliptic curves
than were found in our prior work by using various heuristics ("old and new"
cohomology classes, dimensions of Eisenstein subspaces) to predict the
existence of elliptic curves of various conductors, and then by using more
sophisticated search techniques (for instance, torsion subgroups, twisting, and
the Cremona-Lingham algorithm) to find them. We then compute further invariants
of these curves, such as their rank and representatives of all isogeny classes.
Our enumeration includes conjecturally the first elliptic curves of ranks 1 and
2 over this field, which occur at levels of norm 719 and 9173 respectively
Photoelectron spectra of anionic sodium clusters from time-dependent density-functional theory in real-time
We calculate the excitation energies of small neutral sodium clusters in the
framework of time-dependent density-functional theory. In the presented
calculations, we extract these energies from the power spectra of the dipole
and quadrupole signals that result from a real-time and real-space propagation.
For comparison with measured photoelectron spectra, we use the ionic
configurations of the corresponding single-charged anions. Our calculations
clearly improve on earlier results for photoelectron spectra obtained from
static Kohn-Sham eigenvalues
Testing evolutionary tracks of Pre-Main Sequence stars: the case of HD113449
Evolutionary tracks are of key importance for the understanding of star
formation. Unfortunately, tracks published by various groups differ so that it
is fundamental to have observational tests. In order to do this, we intend to
measure the masses of the two components of the Pre-Main Sequence binary
HD113449 by combining radial velocity measurements taken with HARPS, with
infrared interferometric data using AMBER on the VLTI. The spectroscopic orbit
that has already been determined, combined with the first AMBER measurement,
allows us to obtain a very first estimation of the inclination of the binary
system and from this the masses of the two stars. More AMBER measurements of HD
113449 are needed to improve the precision on the masses: in the ESO period P82
two new measurements are scheduled.Comment: 4 pages, 3 figures; to appear in proceedings of Cool Star 15
conference, St.Andrews 200
Multi-wavelength observations of the peculiar red giant HR 3126
Ultraviolet observations of the red giant HR 3126 are combined with multi-wavelength data in order to provide a firmer basis for explaining the arc-minute sized nebula surrounding the object. Possibilities as to the location of HR 3126 on the Hertzsprung-Russel diagram, and to the formation mechanisms of the reflection nebula IC 2220 associated with it, are summarized
Relationship between HER2 expression and efficacy with first-line trastuzumab emtansine compared with trastuzumab plus docetaxel in TDM4450g: a randomized phase II study of patients with previously untreated HER2-positive metastatic breast cancer.
IntroductionThe purpose of this study was to retrospectively explore the relationship between human epidermal growth factor receptor 2 (HER2) messenger RNA (mRNA) expression and efficacy in patients receiving trastuzumab plus docetaxel (HT) or trastuzumab emtansine (T-DM1).MethodsPatients with HER2-positive, locally advanced or metastatic breast cancer (MBC) were randomly assigned to HT (n=70) or T-DM1 (n=67). HER2 status was assessed locally using immunohistochemistry or fluorescence in situ hybridization and confirmed retrospectively by central testing. HER2 mRNA expression was assessed using quantitative reverse transcriptase polymerase chain reaction.ResultsHER2 mRNA levels were obtained for 116/137 patients (HT=61; T-DM1=55). Median pretreatment HER2 mRNA was 8.9. The risk of disease progression in the overall population was lower with T-DM1 than with HT (hazard ratio (HR)=0.59; 95% confidence interval (CI) 0.36 to 0.97). This effect was more pronounced in patients with HER2 mRNA≥median (HR=0.39; 95% CI 0.18 to 0.85) versus ConclusionsThis exploratory analysis suggests that while overall, patients with HER2-positive MBC show improved PFS with T-DM1 relative to HT, the effect is enhanced in patients with tumor HER2 mRNA ≥ median.Trial registrationClinicalTrials.gov NCT00679341
Violation of the `Zero-Force Theorem' in the time-dependent Krieger-Li-Iafrate approximation
We demonstrate that the time-dependent Krieger-Li-Iafrate approximation in
combination with the exchange-only functional violates the `Zero-Force
Theorem'. By analyzing the time-dependent dipole moment of Na5 and Na9+, we
furthermore show that this can lead to an unphysical self-excitation of the
system depending on the system properties and the excitation strength.
Analytical aspects, especially the connection between the `Zero-Force Theorem'
and the `Generalized-Translation Invariance' of the potential, are discussed.Comment: 5 pages, 4 figure
Dust rings and filaments around the isolated young star V1331 Cygni
We characterize the small and large scale environment of the young star V1331
Cygni with high resolution HST/WFPC2 and Digitized Sky Survey images. In
addition to a previously known outer dust ring (~30'' in diameter), the
HST/WFPC2 scattered light image reveals an inner dust ring for the first time.
This ring has a maximum radius of 6.5'' and is possibly related to a molecular
envelope. Large-scale optical images show that V1331 Cyg is located at the tip
of a long dust filament linking it to the dark cloud LDN 981. We discuss the
origin of the observed dust morphology and analyze the object's relation to its
parent dark cloud LDN 981. Finally, based on recent results from the
literature, we investigate the properties of V1331 Cyg and conclude that in its
current state the object does not show suffcient evidence to be characterized
as an FU Ori object.Comment: 15 pages ApJ preprint style including 3 figures, accepted for
publication in ApJ (Feb. 2007
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