Comment on Experiments Related to the Aharonov-Bohm Phase Shift

Recent experiments undertaken by Caprez, Barwick, and Batelaan should clarify the connections between classical and quantum theories in connection with the Aharonov-Bohm phase shift. It is pointed out that resistive aspects for the solenoid current carriers play a role in the classical but not the quantum analysis for the phase shift. The observed absence of a classical lag effect for a macroscopic solenoid does not yet rule out the possibility of a lag explanation of the observed phase shift for a microscopic solenoid.Comment: 9 page

Blackbody Radiation and the Scaling Symmetry of Relativistic Classical Electron Theory with Classical Electromagnetic Zero-Point Radiation

It is pointed out that relativistic classical electron theory with classical electromagnetic zero-point radiation has a scaling symmetry which is suitable for understanding the equilibrium behavior of classical thermal radiation at a spectrum other than the Rayleigh-Jeans spectrum. In relativistic classical electron theory, the masses of the particles are the only scale-giving parameters associated with mechanics while the action-angle variables are scale invariant. The theory thus separates the interaction of the action variables of matter and radiation from the scale-giving parameters. Classical zero-point radiation is invariant under scattering by the charged particles of relativistic classical electron theory. The basic ideas of the matter -radiation interaction are illustrated in a simple relativistic classical electromagnetic example.Comment: 18 page

The Blackbody Radiation Spectrum Follows from Zero-Point Radiation and the Structure of Relativistic Spacetime in Classical Physics

The analysis of this article is entirely within classical physics. Any attempt to describe nature within classical physics requires the presence of Lorentz-invariant classical electromagnetic zero-point radiation so as to account for the Casimir forces between parallel conducting plates at low temperatures. Furthermore, conformal symmetry carries solutions of Maxwell's equations into solutions. In an inertial frame, conformal symmetry leaves zero-point radiation invariant and does not connect it to non-zero-temperature; time-dilating conformal transformations carry the Lorentz-invariant zero-point radiation spectrum into zero-point radiation and carry the thermal radiation spectrum at non-zero temperature into thermal radiation at a different non-zero-temperature. However, in a non-inertial frame, a time-dilating conformal transformation carries classical zero-point radiation into thermal radiation at a finite non-zero-temperature. By taking the no-acceleration limit, one can obtain the Planck radiation spectrum for blackbody radiation in an inertial frame from the thermal radiation spectrum in an accelerating frame. Here this connection between zero-point radiation and thermal radiation is illustrated for a scalar radiation field in a Rindler frame undergoing relativistic uniform proper acceleration through flat spacetime in two spacetime dimensions. The analysis indicates that the Planck radiation spectrum for thermal radiation follows from zero-point radiation and the structure of relativistic spacetime in classical physics.Comment: 21 page

Complex Physics in Cluster Cores: Showstopper for the Use of Clusters for Cosmology?

The influence of cool galaxy cluster cores on the X-ray luminosity--gravitational mass relation is studied with Chandra observations of 64 clusters in the HIFLUGCS sample. As preliminary results we find (i) a significant offset of cool core (CC) clusters to the high luminosity (or low mass) side compared to non-cool core (NCC) clusters, (ii) a smaller scatter of CC clusters compared to NCC clusters, (iii) a decreasing fraction of CC clusters with increasing cluster mass, (iv) a reduced scatter in the luminosity--mass relation for the entire sample if the luminosity is scaled properly with the central entropy. The implications of these results on the intrinsic scatter are discussed.Comment: 6 pages; to appear in the proceedings of the conference Heating vs. Cooling in Galaxies and Clusters of Galaxies, edited by H. Boehringer, P. Schuecker, G.W. Pratt, and A. Finoguenov. Dedicated to the memory of Peter Schuecke

LAND USE PLANNING ISSUES

Land Economics/Use,

Rural Nonfarm Employment Under Trade Reform Evidence From Vietnam, 1993-2002

Vietnam?s rural economy has substantially diversified over the past two decades. The rural nonfarm sector has grown rapidly and became an important source of employment and income for rural households. This growing nonfarm employment was associated with radical changes in the trade policy reform that has put the country to the top two or three performers in the developing world. This paper examines the potential effect of the trade policy reform on nonfarm employment in rural Vietnam during the period 1993-2002. It proposes two trade openness indices that allow changes in the trade policy at the macro level to be transmitted to rural households. The results reveal that the trade policy reform does have a material impact on rural nonfarm employment. While a more liberalized agricultural sector encourages nonfarm diversification, a lower protection level in the nonfarm sector discourages individual participation in nonfarm income-generating activities.Trade liberalization, trade policy reform, rural nonfarm employment, Vietnam

Space-Time Trellis and Space-Time Block Coding Versus Adaptive Modulation and Coding Aided OFDM for Wideband Channels

Abstract—The achievable performance of channel coded spacetime trellis (STT) codes and space-time block (STB) codes transmitted over wideband channels is studied in the context of schemes having an effective throughput of 2 bits/symbol (BPS) and 3 BPS. At high implementational complexities, the best performance was typically provided by Alamouti’s unity-rate G2 code in both the 2-BPS and 3-BPS scenarios. However, if a low complexity implementation is sought, the 3-BPS 8PSK space-time trellis code outperfoms the G2 code. The G2 space-time block code is also combined with symbol-by-symbol adaptive orthogonal frequency division multiplex (AOFDM) modems and turbo convolutional channel codecs for enhancing the system’s performance. It was concluded that upon exploiting the diversity effect of the G2 space-time block code, the channel-induced fading effects are mitigated, and therefore, the benefits of adaptive modulation erode. In other words, once the time- and frequency-domain fades of the wideband channel have been counteracted by the diversity-aided G2 code, the benefits of adaptive modulation erode, and hence, it is sufficient to employ fixed-mode modems. Therefore, the low-complexity approach of mitigating the effects of fading can be viewed as employing a single-transmitter, single-receiver-based AOFDM modem. By contrast, it is sufficient to employ fixed-mode OFDM modems when the added complexity of a two-transmitter G2 scheme is affordable

Household Demand, Network Externality Effects and Intertemporal Price Discrimination

This paper examines the optimality of intertemporal price discrimination when network externality effects are present in the consumption of a durable good. We conduct our study in two settings. In a model with two household types, utilities are dependent on the cumulative proportion of households that have purchased the durable good. Next, in a model with a continuum of household types, we extend the analysis to the case where households consume both a durable good and a stream of non-durable goods. We show that in both settings, the presence of network externalities facilitates a sales strategy with intertemporal price discrimination.Intertemporal price discrimination, durable good, household demand, network externality