76,350 research outputs found
The importance of live binary evolution in numerical simulations of binaries embedded in circumbinary discs
No full textThe shrinking of a binary orbit driven by the interaction with a gaseous circumbinary disc, initially advocated as a potential way to catalyse the binary merger, has recently been debated in the case of geometrically thick (i.e. with H/R ≥ 0.1) discs. However, a clear consensus is still missing mainly owing to numerical limitations, such as fixed orbit binaries or lack of resolution inside the cavity carved by the binary in its circumbinary disc. In this work, we assess the importance of evolving the binary orbit by means of hydrodynamic simulations performed with the code gizmo in meshless finite mass mode. In order to model the interaction between equal mass circular binaries and their locally isothermal circumbinary discs, we enforce hyper-Lagrangian resolution inside the cavity. We find that fixing the binary orbit ultimately leads to an overestimate of the gravitational torque that the gas exerts on the binary and an underestimate of the torque due to the accretion of material on to the binary components. Furthermore, we find that the modulation of the accretion rate on the binary orbital period is strongly suppressed in the fixed orbit simulation, while it is clearly present in the live binary simulations. This has potential implications for the prediction of the observable periodicities in massive black hole binary candidates
A Probabilistic Short-Term Water Demand Forecasting Model Based on the Markov Chain
No full textThis paper proposes a short-term water demand forecasting method based on the use of the Markov chain. This method provides estimates of future demands by calculating probabilities that the future demand value will fall within pre-assigned intervals covering the expected total variability. More specifically, two models based on homogeneous and non-homogeneous Markov chains were developed and presented. These models, together with two benchmark models (based on artificial neural network and naïve methods), were applied to three real-life case studies for the purpose of forecasting the respective water demands from 1 to 24 h ahead. The results obtained show that the model based on a homogeneous Markov chain provides more accurate short-term forecasts than the one based on a non-homogeneous Markov chain, which is in line with the artificial neural network model. Both Markov chain models enable probabilistic information regarding the stochastic demand forecast to be easily obtained
Markov Chain based model for probabilistic short term water demand forecasting
No full textThe methodology proposed here is aimed at providing both the deterministic water demand forecast and an estimation of the uncertainty affecting this forecast. Two models based on non-homogeneous and homogeneous Markov Chains (named Markov Chain A - MCA and Markov Chain B – MCB, respectively) are developed. These models are applied to three real case-studies with the aim of forecasting hourly water consumptions up to 6 hours ahead. The results obtained show that model based on the homogeneous Markov Chain (MCB) provides more accurate short term forecasts than the non-homogeneous Markov Chain model (MCA) and concurrently is capable of providing useful information about the forecasting uncertainty
The Benefits of Being Economics Professor A (and not Z)
No full textAlphabetic name ordering on multi-authored academic papers, which is the convention in the economics discipline and various other disciplines, is to the advantage of people whose last name initials are placed early in the alphabet. As it turns out, Professor A, who has been a first author more often than Professor Z, will have published more articles and experienced afaster growth rate over the course of her career as a result of reputation and visibility. Moreover, authors know that name ordering matters and indeed take ordering seriously: Several characteristics of an author group composition determine the decision to deviate from the default alphabetic name order to a significant extent.performance measurement, incentives, economists, name ordering
Final word on Jersey Dutch
No full textIn this article, William Z. Shetter compares and contrasts the dialects that developed between different Dutch colonies in the New World. He explores in-depth the nuances of Jersey Dutch, and provides theories to explain how Dutch and colonial languages blended. The article is reprinted from American Speech, December 1958, Volum XXXIII, No. 4
Modular invariance in the gapped XYZ spin-1/2 chain
No full textWe show that the elliptic parametrization of the coupling constants of the quantum XYZ spin chain can be analytically extended outside of their natural domain, to cover the whole phase diagram of the model, which is composed of 12 adjacent regions, related to one another by a spin rotation. This extension is based on the modular properties of the elliptic functions and we show how rotations in parameter space correspond to the double covering PGL(2,Z) of the modular group, implying that the partition function of the XYZ chain is invariant under this group in parameter space, in the same way as a conformal field theory partition function is invariant under the modular group acting in real space. The encoding of the symmetries of the model into the modular properties of the partition function could shed light on the general structure of integrable models
Desilylation of (Z)-α-dimethylphenylsilyl vinyl sulfides with fluoride ion: Revised mechanism for phenyl group migration in substrates containing an electron-withdrawing group β to the sulfur
No full textA detailed investigation of the desilylation of (Z)-α-dimethylphenylsilyl vinyl sulfides with fluoride ion has shown that in substrates containing an electron-withdrawing group β to the sulfur, phenyl group migration occurs as a result of a fluoride ion catalyzed retro-Michael reaction
The role of a newly-identified heterologous crosstalk between G-Protein coupled seven trasmembrane span receptors- Chemokine Receptor CXCR4 and Complement C3aR in Human hemato-lymphopoiesis and Innate Immunity
No full textThe role of a newly-identified heterologous crosstalk between G-Protein coupled seven trasmembrane span receptors- Chemokine Receptor CXCR4 and Complement C3aR in Human hemato-lymphopoiesis and Innate Immunit
Tunable relativistic quasiparticle electronic and excitonic behavior of the FAPb(I1−xBrx)3alloy
No full textWe study the structural, electronic, and excitonic properties of mixed FAPb(I1−xBrx)30 ≤x≤ 1 alloys by first-principles density functional theory as well as quasiparticle GW and Bethe Salpeter equation (BSE) approaches with the inclusion of relativistic effects through spin orbit coupling. Our results show that the system volume decreases with increasing Br content. The quasiparticle band gaps vary from 1.47 eV for pure α-FAPbI3to 2.20 eV for Br-rich α-FAPbBr3and show stronger correlation with the structural changes. The optical property analysis reveals that the overall excitonic peaks are blue shifted with the Br fraction. Our results further reveal strong Br concentration dependence of the variation in the exciton binding energy (from 74 to 112 meV) and the carrier effective masses as well as the high frequency dielectric constants. These findings provide a way to tune the carrier transport properties of the material by doping, which could be utilized to improve the short circuit currents and power conversion efficiencies in multijunction solar cell devices
Flat epithelial atypia on core needle biopsy: which is the right management?
No full textThe clinical significance and management (surgical excision vs. follow-up) of the patients with the diagnosis of flat epithelial atypia (FEA) on core needle biopsy (CNB) are actually under discussion. Using standardized criteria and precise terminology, we analyzed retrospectively our CNB diagnosis of FEA, dividing patients with pure FEA as the most advanced pathologic lesion from patients with FEA associated to atypical ductal hyperplasia (FEA+ADH). Both the categories were correlated with radiologic data and findings on subsequent surgery. We evaluated 875 core needle biopsies (11-gauge stereotactic vacuum-assisted procedure), performed over a 5-year period. A CNB diagnosis of pure FEA was made in 33/875 (3.7%) cases; in other 11 (1.2%) cases we observed the coexistence of FEA and ADH. Subsequent surgical excisions were available in 20/33 pure FEA and in 10/11 FEA+ADH: of the 20 patients with pure FEA on CNB, none had either ductal carcinoma in situ or invasive carcinoma in their excisional biopsy, whereas 3/10 (30%) FEA+ADH on CNB showed, at subsequent surgery, more advanced lesions (2 ductal carcinoma in situ, 1 invasive carcinoma). Our results suggest that patients with an 11-gauge vacuum-assisted CNB diagnosis of pure FEA (especially if related to a small radiologic target, completely or almost completely removed by the needle biopsy procedure) could be spared surgical excision and managed with close radiologic follow-u
- …
