872 research outputs found
Simulating solute transport in an aggregated soil with the dual-porosity model: measured and optimized parameter values
The capability of the first-order, dual-porosity model, which explicitly accounts for non-ideal transport caused by the presence of ‘immobile’ water, to predict the non-ideal transport of non-sorbing solute in a constructed aggregated soil has been investigated. Miscible-displacement experiments performed with a well-characterized aggregated soil and a non-reactive tracer (pentafluorobenzoate) served as the source of the data. Values for the input parameters associated with physical non-equilibrium were determined independently and compared with values obtained by curve fitting of the experimental measurements. The calculated and optimized values compared well, suggesting that the non-equilibrium parameters represent actual physical phenomen
On a class of translation planes of square order
AbstractA class of translation planes of order q2, where q = pr, p is a prime, p ⩾7, p ≠± 1 (mod 10) and r is an odd natural number is constructed and the translation complements of these planes are determined. A property shared by all these planes is that the translation complement fixes a distinguished point and divides the remaining distinguished points into two orbits of length q and q2 − q. The order of the translation complement is rq(q − 1)2 except for q = 7 and q = 13. The translation complements of these exceptional cases are also briefly studied. The class of planes considered in this paper are distinct from the classes of translation planes of S.D. Cohen and M.J. Ganley [Quart. J. Math. Oxford, 35 (1984) 101–113]
Supersymmetric solutions of PT-/non-PT-symmetric and non-Hermitian Screened Coulomb potential via Hamiltonian hierarchy inspired variational method
The supersymmetric solutions of PT-symmetric and Hermitian/non-Hermitian
forms of quantum systems are obtained by solving the Schrodinger equation for
the Exponential-Cosine Screened Coulomb potential. The Hamiltonian hierarchy
inspired variational method is used to obtain the approximate energy
eigenvalues and corresponding wave functions.Comment: 13 page
On-site Coulomb interaction and the magnetism of (GaMn)N and (GaMn)As
We use the local density approximation (LDA) and LDA+U schemes to study the
magnetism of (GaMn)As and (GaMn)N for a number of Mn concentrations and varying
number of holes. We show that for both systems and both calculational schemes
the presence of holes is crucial for establishing ferromagnetism. For both
systems, the introduction of increases delocalization of the holes and,
simultaneously, decreases the p-d interaction. Since these two trends exert
opposite influences on the Mn-Mn exchange interaction the character of the
variation of the Curie temperature (T) cannot be predicted without direct
calculation. We show that the variation of T is different for two systems.
For low Mn concentrations we obtain the tendency to increasing T in the
case of (GaMn)N whereas an opposite tendency to decreasing T is obtained
for (GaMn)As. We reveal the origin of this difference by inspecting the
properties of the densities of states and holes for both systems. The main body
of calculations is performed within a supercell approach. The Curie
temperatures calculated within the coherent potential approximation to atomic
disorder are reported for comparison. Both approaches give similar qualitative
behavior. The results of calculations are related to the experimental data.Comment: to appear in Physical Review
Semiclassical quantization of the hydrogen atom in crossed electric and magnetic fields
The S-matrix theory formulation of closed-orbit theory recently proposed by
Granger and Greene is extended to atoms in crossed electric and magnetic
fields. We then present a semiclassical quantization of the hydrogen atom in
crossed fields, which succeeds in resolving individual lines in the spectrum,
but is restricted to the strongest lines of each n-manifold. By means of a
detailed semiclassical analysis of the quantum spectrum, we demonstrate that it
is the abundance of bifurcations of closed orbits that precludes the resolution
of finer details. They necessitate the inclusion of uniform semiclassical
approximations into the quantization process. Uniform approximations for the
generic types of closed-orbit bifurcation are derived, and a general method for
including them in a high-resolution semiclassical quantization is devised
Fluorescent carbon dioxide indicators
Over the last decade, fluorescence has become the dominant tool in biotechnology and medical imaging. These exciting advances have been underpinned by the advances in time-resolved techniques and instrumentation, probe design, chemical / biochemical sensing, coupled with our furthered knowledge in biology. Complementary volumes 9 and 10, Advanced Concepts of Fluorescence Sensing: Small Molecule Sensing and Advanced Concepts of Fluorescence Sensing: Macromolecular Sensing, aim to summarize the current state of the art in fluorescent sensing. For this reason, Drs. Geddes and Lakowicz have invited chapters, encompassing a broad range of fluorescence sensing techniques. Some chapters deal with small molecule sensors, such as for anions, cations, and CO2, while others summarize recent advances in protein-based and macromolecular sensors. The Editors have, however, not included DNA or RNA based sensing in this volume, as this were reviewed in Volume 7 and is to be the subject of a more detailed volume in the near future
Assessment of Birth Defects and Cancer Risk in Children Conceived via in Vitro Fertilization in the US
Importance: Children with birth defects have a greater risk of developing cancer, but this association has not yet been evaluated in children conceived with in vitro fertilization (IVF). Objective: To assess whether the association between birth defects and cancer is greater in children conceived via IVF compared with children conceived naturally. Design, Setting, and Participants: This cohort study of live births, birth defects, and cancer from Massachusetts, New York, North Carolina, and Texas included 1000639 children born to fertile women and 52776 children conceived via IVF (using autologous oocytes and fresh embryos) during 2004-2016 in Massachusetts and North Carolina, 2004-2015 in New York, and 2004-2013 in Texas. Children were followed up for an average of 5.7 years (6008985 total person-years of exposure). Data analysis was conducted from April 1 to August 31, 2020. Exposures: Conception by IVF for state residents who gave birth to liveborn singletons during the study period. Birth defect diagnoses recorded by statewide registries. Main Outcomes and Measures: Cancer diagnosis as recorded by state cancer registries. Cox proportional hazards regression models were used to estimate hazard ratios (HRs) and 95% CIs for birth defect-cancer associations separately in fertile and IVF groups. Results: A total of 1000639 children (51.3% boys; 69.7% White; and 38.3% born between 2009-2012) were in the fertile group and 52776 were in the IVF group (51.3% boys; 81.3% White; and 39.6% born between 2009-2012). Compared with children without birth defects, cancer risks were higher among children with a major birth defect in the fertile group (hazard ratio [HR], 3.15; 95% CI, 2.40-4.14) and IVF group (HR, 6.90; 95% CI, 3.73-12.74). The HR of cancer among children with a major nonchromosomal defect was 2.07 (95% CI, 1.47-2.91) among children in the fertile group and 4.04 (95% CI, 1.86-8.77) among children in the IVF group. The HR of cancer among children with a chromosomal defect was 15.45 (95% CI, 10.00-23.86) in the fertile group and 38.91 (95% CI, 15.56-97.33) in the IVF group. Conclusions and Relevance: This study found that among children with birth defects, those conceived via IVF were at greater risk of developing cancer compared with children conceived naturally
Particle density fluctuations
Event-by-event fluctuations in the multiplicities of charged particles and
photons at SPS energies are discussed. Fluctuations are studied by controlling
the centrality of the reaction and rapidity acceptance of the detectors.
Results are also presented on the event-by-event study of correlations between
the multiplicity of charged particles and photons to search for DCC-like
signals.Comment: Talk presented at Quark Matter 2002, Nantes, Franc
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