2,107 research outputs found
Estate Taxes, Life Insurance, and Small Business
One criticism of the estate tax is that it prevents the owners of family businesses from passing their enterprises to their children. The problem is that it may be difficult to pay estate taxes without liquidating the business. A natural question is why individuals with such concerns do not purchase enough life insurance to meet their estate tax liabilities. This paper examines whether and how people use life insurance to deal with the estate tax. We find that, other things being the same, business owners purchase more life insurance than other individuals. However, on the margin, their insurance purchases are less responsive to estate tax considerations and they are less likely to have the wherewithal to meet estate tax liabilities out of liquid assets plus insurance.
Consequences of Transport Low-Carbon Transitions and the Carbon, Land and Water Footprints of Different Fuel Options in The Netherlands
Transport greenhouse gas emissions are mainly caused by the use of fossil fuels, e.g., gasoline and diesel. This case study for the Netherlands calculates how alternative fuels, e.g., electricity, hydrogen or biofuels, contribute to policy aims to decarbonize transport. Alternative fuels, produced in various ways, have different carbon (CF), land (LFs) and water footprints (WFs). This study assesses CFs, LFs and WFs for fuels (kgCO2e/m2/m3 per GJ), showing differences among fuels dependent on primary energy sources. It calculates CFs, LFs and WFs for four scenarios with different fuels. The biofuel scenario is not attractive. CFs slightly decrease, while LFs and WFs increase enormously. The electricity scenario has small CFs and the smallest LFs and WFs, but this is only when using wind or solar energy. If storage is needed and hydrogen is produced using wind energy, CFs double from 3055 to 7074 kg CO2e, LFs increase from 15 106 to 43 106 m2 and WFs from 3 106 to 37 106 m3 compared to the electricity scenario. The case study shows that wise fuel choices contribute to policy aims to decarbonize transport, although LFs and WFs are also important to consider. These case study results are relevant for sustainable transportation transitions worldwide
Calculation of radiation losses in cylinder symmetric high pressure discharges by means of a digital computer
Sulfur isotope fractionation between fluid and andesitic melt : an experimental study
Author Posting. © The Author(s), 2014. This is the author's version of the work. It is posted here by permission of Elsevier for personal use, not for redistribution. The definitive version was published in Geochimica et Cosmochimica Acta 142 (2014): 501-521, doi:10.1016/j.gca.2014.07.015.Glasses produced from decompression experiments conducted by Fiege et al. (2014a) were used to
investigate the fractionation of sulfur isotopes between fluid and andesitic melt upon magma
degassing. Starting materials were synthetic glasses with a composition close to a Krakatau dacitic
andesite. The glasses contained 4.55 to 7.95 wt% H2O, ~140 to 2700 ppm sulfur (S), and 0 to 1000
ppm chlorine (Cl). The experiments were carried out in internally heated pressure vessels (IHPV) at
1030°C and oxygen fugacities (fO2) ranging from QFM+0.8 log units up to QFM+4.2 log units (QFM:
quartz-fayalite-magnetite buffer). The decompression experiments were conducted by releasing
pressure (P) continuously from ~400 MPa to final P of 150, 100, 70 and 30 MPa. The decompression
rate (r) ranged from 0.01 to 0.17 MPa/s. The samples were annealed for 0 to 72 h (annealing time, tA)
at the final P and quenched rapidly from 1030°C to room temperature (T).
The decompression led to the formation of a S-bearing aqueous fluid phase due to the relatively large
fluid-melt partitioning coefficients of S. Secondary ion mass spectrometry (SIMS) was used to
determine the isotopic composition of the glasses before and after decompression. Mass balance
calculations were applied to estimate the gas-melt S isotope fractionation factor αg-m.
No detectable effect of r and tA on αg-m was observed. However, SIMS data revealed a remarkable
increase of αg-m from ~0.9985 ± 0.0007 at >QFM+3 to ~1.0042 ± 0.0042 at ~QFM+1. Noteworthy, the
isotopic fractionation at reducing conditions was about an order of magnitude larger than predicted by previous works. Based on our experimental results and on previous findings for S speciation in fluid
and silicate melt a new model predicting the effect of fO2 on αg-m (or Δ34S g-m) in andesitic systems at
1030°C is proposed. Our experimental results as well as our modeling are of high importance for the
interpretation of S isotope signatures in natural samples (e.g., melt inclusions or volcanic gases).This project was supported by the German Science Foundation (BE1720/25-1 to H. Behrens), by the
German National Academic Foundation, and by Collaborative Research Grants from the U.S. National
Science Foundation (EAR-0838482 to C. W. Mandeville, EAR-0838436 to N. Shimizu, and EAR-
0838328 to K. A. Kelley)
Structured matrices, continued fractions, and root localization of polynomials
We give a detailed account of various connections between several classes of
objects: Hankel, Hurwitz, Toeplitz, Vandermonde and other structured matrices,
Stietjes and Jacobi-type continued fractions, Cauchy indices, moment problems,
total positivity, and root localization of univariate polynomials. Along with a
survey of many classical facts, we provide a number of new results.Comment: 79 pages; new material added to the Introductio
Local asymptotic normality for qubit states
We consider n identically prepared qubits and study the asymptotic properties
of the joint state \rho^{\otimes n}. We show that for all individual states
\rho situated in a local neighborhood of size 1/\sqrt{n} of a fixed state
\rho^0, the joint state converges to a displaced thermal equilibrium state of a
quantum harmonic oscillator. The precise meaning of the convergence is that
there exist physical transformations T_{n} (trace preserving quantum channels)
which map the qubits states asymptotically close to their corresponding
oscillator state, uniformly over all states in the local neighborhood.
A few consequences of the main result are derived. We show that the optimal
joint measurement in the Bayesian set-up is also optimal within the pointwise
approach. Moreover, this measurement converges to the heterodyne measurement
which is the optimal joint measurement of position and momentum for the quantum
oscillator. A problem of local state discrimination is solved using local
asymptotic normality.Comment: 16 pages, 3 figures, published versio
Electron Accumulation and Emergent Magnetism in LaMnO3/SrTiO3 Heterostructures
Emergent phenomena at polar-nonpolar oxide interfaces have been studied
intensely in pursuit of next-generation oxide electronics and spintronics. Here
we report the disentanglement of critical thicknesses for electron
reconstruction and the emergence of ferromagnetism in polar-mismatched
LaMnO3/SrTiO3 (001) heterostructures. Using a combination of element-specific
X-ray absorption spectroscopy and dichroism, and first-principles calculations,
interfacial electron accumulation and ferromagnetism have been observed within
the polar, antiferromagnetic insulator LaMnO3. Our results show that the
critical thickness for the onset of electron accumulation is as thin as 2 unit
cells (UC), significantly thinner than the observed critical thickness for
ferromagnetism of 5 UC. The absence of ferromagnetism below 5 UC is likely
induced by electron over-accumulation. In turn, by controlling the doping of
the LaMnO3, we are able to neutralize the excessive electrons from the polar
mismatch in ultrathin LaMnO3 films and thus enable ferromagnetism in films as
thin as 3 UC, extending the limits of our ability to synthesize and tailor
emergent phenomena at interfaces and demonstrating manipulation of the
electronic and magnetic structures of materials at the shortest length scales.Comment: Accepted by Phys. Rev. Let
Evaluating the ecology of Spinosaurus: Shoreline generalist or aquatic pursuit specialist?
The giant theropod Spinosaurus was an unusual animal and highly derived in many ways, and interpretations of its ecology remain controversial. Recent papers have added considerable knowledge of the anatomy of the genus with the discovery of a new and much more complete specimen, but this has also brought new and dramatic interpretations of its ecology as a highly specialised semi-aquatic animal that actively pursued aquatic prey. Here we assess the arguments about the functional morphology of this animal and the available data on its ecology and possible habits in the light of these new finds. We conclude that based on the available data, the degree of adaptations for aquatic life are questionable, other interpretations for the tail fin and other features are supported (e.g., socio-sexual signalling), and the pursuit predation hypothesis for Spinosaurus as a “highly specialized aquatic predator” is not supported. In contrast, a ‘wading’ model for an animal that predominantly fished from shorelines or within shallow waters is not contradicted by any line of evidence and is well supported. Spinosaurus almost certainly fed primarily from the water and may have swum, but there is no evidence that it was a specialised aquatic pursuit predator
Tensor completion in hierarchical tensor representations
Compressed sensing extends from the recovery of sparse vectors from
undersampled measurements via efficient algorithms to the recovery of matrices
of low rank from incomplete information. Here we consider a further extension
to the reconstruction of tensors of low multi-linear rank in recently
introduced hierarchical tensor formats from a small number of measurements.
Hierarchical tensors are a flexible generalization of the well-known Tucker
representation, which have the advantage that the number of degrees of freedom
of a low rank tensor does not scale exponentially with the order of the tensor.
While corresponding tensor decompositions can be computed efficiently via
successive applications of (matrix) singular value decompositions, some
important properties of the singular value decomposition do not extend from the
matrix to the tensor case. This results in major computational and theoretical
difficulties in designing and analyzing algorithms for low rank tensor
recovery. For instance, a canonical analogue of the tensor nuclear norm is
NP-hard to compute in general, which is in stark contrast to the matrix case.
In this book chapter we consider versions of iterative hard thresholding
schemes adapted to hierarchical tensor formats. A variant builds on methods
from Riemannian optimization and uses a retraction mapping from the tangent
space of the manifold of low rank tensors back to this manifold. We provide
first partial convergence results based on a tensor version of the restricted
isometry property (TRIP) of the measurement map. Moreover, an estimate of the
number of measurements is provided that ensures the TRIP of a given tensor rank
with high probability for Gaussian measurement maps.Comment: revised version, to be published in Compressed Sensing and Its
Applications (edited by H. Boche, R. Calderbank, G. Kutyniok, J. Vybiral
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