Financial Giffen goods: Examples and counterexamples

In the basic Markowitz and Merton models, a stock’s weight in efficient portfolios goes up if its expected rate of return goes up. Put differently, there are no financial Giffen goods. By an example from mortgage choice we illustrate that for more complicated portfolio problems Giffen effects do occur.     

Identification of one-phonon and two-phonon γ-vibrational bands in odd-ZNb nucleus

Collective bands in the neutron-rich ¹⁰³Nb nucleus have been investigated by measuring prompt γ-rays following spontaneous fission of ²⁵²Cf. Three new bands have been identified. The band based on the 716.8 keV level is proposed as a candidate for the Kπ=9/²⁺$K^{\pi }=9/2^{+}$ one-phonon γ  -vibrational band, and the band built on the 1282.1 keV level is proposed as a candidate for the Kπ=13/²⁺$K^{\pi }=13/2^{+}$ two-phonon γ-vibrational band. The two-phonon γ-vibrational band is the first such band identified in odd-Z nuclei.     

On Accuracy Problems for Semi-Analytical Sensitivity Analyses

Abstract

The semi-analytical method of sensitivity analysis combines ease of implementation with computational efficiency. A major drawback to this method, however, is that severe accuracy problems have recently been reported. A complete error analysis for a beam problem with changing length is carried out in this paper. It is shown that the sensitivity error is proportional to the relative length difference, but in agreement with Eq. 3.8. The approximate pseudo loads thus violate moment equilibrium for rigid body motion while the correct pseudo loads do not.

It might be a good idea to modify the approximate pseudo loads in order to obtain general load equilibrium with rigid body motions. Such a method would be readily applicable for any element type, whether analytical expressions for the element stiffnesses are available or not. This topic is postponed for a future study.     

Low-Power Testing of Losses in Millimeter-Wave Transmission Lines for High-Power Applications

We report the measurement of small losses in transmission line (TL) components intended for high-power millimeter-wave applications. Measurements were made using two different low-power techniques: a coherent technique using a vector network analyzer (VNA) and an incoherent technique using a radiometer. The measured loss in a 140 GHz 12.7 mm diameter TL system, consisting of 1.7 m of circular corrugated waveguide and three miter bends, is dominated by the miter bend loss. The measured loss was 0.3 ± 0.1 dB per miter bend using a VNA; and 0.22 ± 0.1 dB per miter bend using a radiometer. Good agreement between the two measurement techniques implies that both are useful for measuring small losses. To verify the methodology, the VNA technique was employed to measure the extremely small transmission loss in a 170 GHz ITER prototype TL system consisting of three lengths of 1 m, 63.5 mm diameter, circular corrugated waveguide and two miter bends. The measured loss of 0.05 ± 0.02 dB per miter bend may be compared with the theoretical loss of 0.027 dB per miter bend. These results suggest that low-power testing of TL losses, utilizing a small, simple TL system and a VNA, is a reliable method for evaluating performance of low-loss millimeter-wave TL components intended for use in high-power applications.     

Connecting orbits in perturbed systems

We apply Newton’s method and continuation techniques to determine heteroclinic connections in perturbed non-autonomous differential equations which do not exist for the underlying unperturbed system. This approach is particularly useful in a higher-dimensional context, where the numerical computation of invariant manifolds is very expensive. A detailed discussion of a four-dimensional model is presented, which describes a pendulum coupled to a harmonic oscillator.     

Sharp vorticity gradients in two-dimensional turbulence and the energy spectrum

Formation of sharp vorticity gradients in two-dimensional (2D) hydrodynamic turbulence and their influence on the turbulent spectra are considered. The analog of the vortex line representation as a transformation to the curvilinear system of coordinates moving together with the di-vorticity lines is developed and compressibility of this mapping appears as the main reason for the formation of the sharp vorticity gradients at high Reynolds numbers. In the case of strong anisotropy the sharp vorticity gradients can generate spectra which fall off as k ^?3 at large k, which appear to take the same form as the Kraichnan spectrum for the enstrophy cascade. For turbulence with weak anisotropy the k dependence of the spectrum due to the sharp gradients coincides with the Saffman spectrum: E(k) ~ k ^?4. Numerical investigations of decaying turbulence reveal exponential growth of di-vorticity with a spatial distributed along straight lines. Thus, indicating strong anisotropy and accordingly the spectrum is close to the k ^?3-spectrum.     

2x40 Gbit/s Polarization Division Multiplexing With Bit Slot Synchronization

Polarization division multiplexing (PDM) can double the spectral efficiency of an optical transmission system. By means of simulation, the 2x40Gbit/s NRZ PDM system performance under polarization mode dispersion (PMD) and chromatic dispersion has been investigated. To realize the best performance, the bit slots of the two channels should be synchronized.     

Microsequencing of proteins recorded in human two-dimensional gel protein databases.

Sixty-six human proteins recorded in the master transformed human epithelial amnion cells (AMA) (55) and keratinocyte (11) two-dimensional gel protein databases have been microsequenced since the last publication of the AMA database (Electrophoresis 1990, 12, 989-1071). Coomassie Brilliant Blue stained protein spots cut from several (up to 40) dry gels were concentrated by elution-concentration gel electrophoresis, electroblotted onto polyvinylidene difluoride membranes and in situ digested with trypsin. The eluting peptides were separated by reversed-phase high performance liquid chromatography (HPLC), collected individually and sequenced. Computer searches using the FASTA and TFASTA programs from the Genetics Computer Group indicated that 29 of the analyzed polypeptides correspond to hitherto unknown proteins.