4,412 research outputs found
Program to calculate pure angular momentum coefficients in jj-coupling
A program for computing pure angular momentum coefficients in relativistic
atomic structure for any scalar one- and two-particle operator is presented.
The program, written in Fortran 90/95 and based on techniques of second
quantization, irreducible tensorial operators, quasispin and the theory of
angular momentum, is intended to replace existing angular coefficient modules
from GRASP92. The new module uses a different decomposition of the coefficients
as sums of products of pure angular momentum coefficients, which depend only on
the tensor rank of the interaction but not on its details, with effective
interaction strengths of specific interactions. This saves memory and reduces
the computational cost of big calculations signficantly
Oxidative Phosphorylation: A Critical Feature and Novel Therapeutic Target in Melanoma Brain Metastases
We recently showed via RNA-sequencing (RNA-seq) analysis of clinical samples that melanoma brain metastases (MBMs) have higher expression of oxidative phosphorylation (OXPHOS) genes (including PPARGC1A or PGC1α) than patient-matched extracranial metastases (ECMs). Thus, the central hypothesis of this dissertation is that OXPHOS plays a critical role in the pathogenesis of MBMs.
RNA-seq analysis identified increased expression of OXPHOS genes in intracranial (ICr) vs. subcutaneous (SQ) xenografts of 4 different human melanoma cell lines. Increased OXPHOS in the ICr xenografts was confirmed by direct metabolite analysis and [U-13C]-glucose tracing analysis. Together, these studies indicate that the brain TME mediates OXPHOS enrichment in MBMs.
The functional significance of OXPHOS in MBM pathogenesis was tested using IACS-010759, a potent OXPHOS inhibitor currently in phase I clinical trials. IACS-010759 treatment of an RCAS-TVA mouse model of spontaneous MBM and lung metastasis significantly decreased the incidence of detectable MBMs but did not affect primary tumor growth or the incidence of lung metastases. To clarify if OXPHOS promotes the formation of MBMs or the outgrowth of micrometastases, we used an imageable experimental MBM model to demonstrate that IACS-010759 treatment prevented the growth of MBMs but did not prevent their formation, and had no effect on the formation or growth of lung metastases. Likewise, knockdown of PGC1α significantly extended the survival of mice challenged by intracranial injection of melanoma cell lines but had no effect on subcutaneous tumor growth.
Hierarchical clustering analysis of surgically resected MBMs by OXPHOS genes identified subsets of MBMs particularly enriched (High-OXPHOS) and depleted (Low-OXPHOS) in OXPHOS. High-OXPHOS MBMs were characterized by mTORC1 pathway activation, immunosuppression, and enhanced glutamine metabolism. IACS-010759 treatment and treatment with the novel glutaminase inhibitor CB839 significantly improved the survival of mice bearing High-OXPHOS, MAPKi-resistant ICr xenografts.
Together these studies indicate that the brain TME mediates OXPHOS enrichment in MBMs. Further, while OXPHOS is not a critical determinant of brain metastasis formation, it plays a crucial role in intracranial tumor growth. These findings suggest that targeting this metabolic pathway and/or its dependencies may be an effective strategy for MBM treatment
Multiconfiguration Dirac-Hartree-Fock energy levels and transition probabilities for 3d^5 in Fe IV
Multiconfiguration Dirac-Hartree-Fock electric quadrupole (E2) and magnetic
dipole (M1) transition probabilities are reported for transitions between
levels of 3d^5 in [Fe IV]. The accuracy of the ab initio energy levels and the
agreement in the length and velocity forms of the line strength for the E2
transitions are used as indicators of accuracy. The present E2 and M1
transition probabilities are compared with earlier Breit-Pauli results and
other theories. An extensive set of transition probabilites with indicators of
accuracy are reported in Appendices A and B. Recommended values of A(E2) +
A(M1) are listed in Appendix C.Comment: 16 pages, three appendices containing accuracy indicators and
recommended values for E2 and M1 transition rate
There\u27s a little bit of bad in every good little girl
https://digitalcommons.ithaca.edu/sheetmusic/1029/thumbnail.jp
There\u27s A Little Bit Of Bad In Every Good Little Girl
https://digitalcommons.library.umaine.edu/mmb-vp/6264/thumbnail.jp
Calculation of reduced coefficients and matrix elements in jj-coupling
A program RCFP will be presented for calculating standard quantities in the
decomposition of many-electron matrix elements in atomic structure theory. The
list of quantities wich are supported by the present program includes the
coefficients of fractional parentage, the reduced coefficients of fractional
parentage, the reduced matrix elements of the unit operator T^{(k)} as well as
the completely reduced matrix elements of the operator W^{(k_jk_q)} in
jj-coupling. These quantities are now available for all subshells (nj) with j
\leq 9/2 including partially filled 9/2-shells. Our program is based on a
recently developed new approach on the spin-angular integration which combines
second quantization and quasispin methods with the theory of angular momentum
in order to obtain a more efficient evaluation of many-electron matrix
elements. An underlying Fortran 90/95 module can directly be used also in
(other) atomic structure codes to accelerate the computation for open-shell
atoms and ions
Aerosol major ion record at Mount Washington
This study examined the seasonal cycles and regional-scale meteorological controls on the chemical properties of bulk aerosols collected from 1999 to 2004 at Mount Washington, the highest peak in the northeastern United States. The concentrations of NH4+ and SO42− peaked during summer months. The pattern for aerosol NO3− was more complicated with relatively high median concentrations characterizing spring and summer months, but with major elevated events occurring during fall, winter, and spring. The seasonal relationship between NH4+ and SO42− indicated that during warmer months a mixture of (NH4)2SO4 and NH4HSO4 was present, while it was mainly the latter in winter. More acidity and higher concentrations of the major species were generally associated with winds from the southwest and west sectors. The highest (≥95th percentile) concentrations of SO42− and NH4+ were associated with air mass transport from major upwind source regions in the Midwest and along the eastern seaboard. The ionic composition and seasonal cycle observed at Mount Washington were similar to those measured at other northeastern sites, but the range and average concentrations were much lower. These differences were exaggerated during wintertime. Included in this paper are several Eulerian case studies of SO2 conversion to SO42− during transit from Whiteface Mountain, New York, to Mount Washington. The calculations suggest a gas-phase SO2 oxidation rate of ∼1–2% per hour and demonstrate the possibility of using these two sites to investigate the chemical evolution of air masses as they move from Midwestern source regions to northern New England
Low significance of evidence for black hole echoes in gravitational wave data
Recent detections of merging black holes allow observational tests of the
nature of these objects. In some proposed models, non-trivial structure at or
near the black hole horizon could lead to echo signals in gravitational wave
data. Recently, Abedi et al. claimed tentative evidence for repeating damped
echo signals following the gravitational-wave signals of the binary black hole
merger events recorded in the first observational period of the Advanced LIGO
interferometers. We reanalyse the same data, addressing some of the
shortcomings of their method using more background data and a modified
procedure. We find a reduced statistical significance for the claims of
evidence for echoes, calculating increased p-values for the null hypothesis of
echo-free noise. The reduced significance is entirely consistent with noise,
and so we conclude that the analysis of Abedi et al. does not provide any
observational evidence for the existence of Planck-scale structure at black
hole horizons.Comment: As accepted by Physical Review
Light attenuation characteristics of glacially-fed lakes
Transparency is a fundamental characteristic of aquatic ecosystems and is highly responsive to changes in climate and land use. The transparency of glacially-fed lakes may be a particularly sensitive sentinel characteristic of these changes. However, little is known about the relative contributions of glacial flour versus other factors affecting light attenuation in these lakes. We sampled 18 glacially-fed lakes in Chile, New Zealand, and the U.S. and Canadian Rocky Mountains to characterize how dissolved absorption, algal biomass (approximated by chlorophyll a), water, and glacial flour contributed to attenuation of ultraviolet radiation (UVR) and photosynthetically active radiation (PAR, 400–700 nm). Variation in attenuation across lakes was related to turbidity, which we used as a proxy for the concentration of glacial flour. Turbidity-specific diffuse attenuation coefficients increased with decreasing wavelength and distance from glaciers. Regional differences in turbidity-specific diffuse attenuation coefficients were observed in short UVR wavelengths (305 and 320 nm) but not at longer UVR wavelengths (380 nm) or PAR. Dissolved absorption coefficients, which are closely correlated with diffuse attenuation coefficients in most non-glacially-fed lakes, represented only about one quarter of diffuse attenuation coefficients in study lakes here, whereas glacial flour contributed about two thirds across UVR and PAR. Understanding the optical characteristics of substances that regulate light attenuation in glacially-fed lakes will help elucidate the signals that these systems provide of broader environmental changes and forecast the effects of climate change on these aquatic ecosystems
dftatom: A robust and general Schr\"odinger and Dirac solver for atomic structure calculations
A robust and general solver for the radial Schr\"odinger, Dirac, and
Kohn--Sham equations is presented. The formulation admits general potentials
and meshes: uniform, exponential, or other defined by nodal distribution and
derivative functions. For a given mesh type, convergence can be controlled
systematically by increasing the number of grid points. Radial integrations are
carried out using a combination of asymptotic forms, Runge-Kutta, and implicit
Adams methods. Eigenfunctions are determined by a combination of bisection and
perturbation methods for robustness and speed. An outward Poisson integration
is employed to increase accuracy in the core region, allowing absolute
accuracies of Hartree to be attained for total energies of heavy
atoms such as uranium. Detailed convergence studies are presented and
computational parameters are provided to achieve accuracies commonly required
in practice. Comparisons to analytic and current-benchmark density-functional
results for atomic number = 1--92 are presented, verifying and providing a
refinement to current benchmarks. An efficient, modular Fortran 95
implementation, \ttt{dftatom}, is provided as open source, including examples,
tests, and wrappers for interface to other languages; wherein particular
emphasis is placed on the independence (no global variables), reusability, and
generality of the individual routines.Comment: Submitted to Computer Physics Communication on August 27, 2012,
revised February 1, 201
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