Spectra of Particles from Laser-Induced Vacuum Decay

The spectrum of electrons and positrons originating from vacuum decay occurring in the collision of two non-colinear laser pulses is obtained. It displays high energy, highly-collimated particle bunches traveling in a direction separate from the laser beams. This result provides an unmistakable signature of the vacuum decay phenomenon and could suggest a new avenue for development of high energy electron and/or positron beams.Comment: 5 pages, 3 figures; typos corrected and references added; version appearing in Physical Review

The Highest Price Ever: The Great NYSE Seat Sale of 1928-1929 and Capacity Constraints

A surge in orders during the stock market boom of the late 1920s collided against the constraint created by the fixed number of brokers on the New York Stock Exchange. Estimates of the determinants of individual stock bid-ask spreads from panel data reveal that spreads jumped when volume spiked, confirming contemporary observers complaints that there were insufficient counterparties. When the position of the NYSE as the dominant exchange became threatened, the management of the exchange proposed a 25 percent increase in the number of seats in February 1929 by issuing a quarter-seat dividend to all members. While such a "stock split" would be expected to leave the aggregate value of the NYSE unchanged, an event study reveals that its value rose in anticipation of increased efficiency. These expectations were justified as bid-ask spreads became less sensitive to peak volume days after the increase in seats.

Attributes of Woodland Caribou Migration Habitat in West-Central British Columbia

We examined sites used by 73 caribou located by radio-tracking during spring migration through a forested travel corridor. The physical and botanical characteristics of these sites were described to find what features (if any) distinguished them from the forest at large. Raised and open aspect, sparse tree cover, free-draining soils, and a simple flora with abundant lichens were features common to all the sites, but were lacking in the denser forest around. Scores for these attributes were ordinated by multidimensional scaling of similarities and differences from site to site. Separate searings for (i) terrain features, (ii) tree cover attributes, and (iii) floristic content each yielded a single cluster of points with few outliers and no particular pattern or trend. The inference is that the sites conformed to a single type with limited variation. A profile of the distinguishing characteristics was compiled and then applied to transects through the general migration area by persons unfamiliar with it beforehand. Sites which matched the profile proved easy to identify, even though they comprised only a small proportion of the area. Sites with high scores for the most distinctive attributes had more caribou at the time of radio-tracking

Role of raltegravir in the management of HIV-1 infection

The development of multiple agents with potent antiretroviral activity against HIV has ushered in a new age of optimism in the management of patients infected with the virus. However, the viruses’ dynamic ability to develop resistance against these agents necessitates the investigation of novel targets for viral suppression. Raltegravir represents a first-in-class agent targeting the HIV integrase enzyme, which is responsible for integration of virally encoded DNA into the host genome. Over the last 5 years, clinical trials data has demonstrated an increasing role for raltegravir in the management of both treatment-experienced and treatment-naïve HIV-1-infected patients. This review focuses on the evidence supporting raltegravir’s efficacy in an array of clinical settings. Other HIV-1 integrase inhibitors in development are also briefly discussed

Acceleration and vacuum temperature

The quantum fluctuations of an "accelerated" vacuum state, that is vacuum fluctuations in the presence of a constant electromagnetic field, can be described by the temperature \TEH. Considering \TEH for the gyromagnetic factor $g=1$ we show that \TEH(g=1)=\THU, where \THU is the Unruh temperature experienced by an accelerated observer. We conjecture that both particle production and nonlinear field effects inherent in the Unruh accelerated observer case are described by the case $g=1$ QED of strong fields. We present rates of particle production for $g=0,1,2$ and show that the case $g=1$ is experimentally distinguishable from $g=0,2$. Therefore, either accelerated observers are distinguishable from accelerated vacuum or there is unexpected modification of the theoretical framework.Comment: 4 pages, 1 figure; expanded discussion of experimental observables, added references, version appearing in Phys Rev