Dark energy, Ricci-nonflat spaces, and the Swampland

It was recently pointed out that the existence of dark energy imposes highly restrictive constraints on effective field theories that satisfy the Swampland conjectures. We provide a critical confrontation of these constraints with the cosmological framework emerging from the Salam-Sezgin model and its string realization by Cvetic, Gibbons, and Pope. We also discuss the implication of the constraints for string model building.Comment: Matching version to be published in PL

REDUCING TRANSPORTATION DAMAGE TO GRAPES AND STRAWBERRIES

In-transit vibration damage to grapes and strawberries results in reduced quality for the consumer and reduced profits for the produce industry. To solve this problem, the first step is to determine which vibrational frequencies are causing the damage. In various tests, grapes and strawberries were subjected to different frequencies at constant force levels. The effects of the vibration treatments were evaluated on the basis of grading, color analysis, firmness, respiration rate and ethylene production rate. The critical frequency was found to lie between 7.5 and 10 Hertz for both commodities. Color change and respiration rate were shown to be good indicators of damage in grapes. Strawberries did not show a significant effect due to color. Firmness was not affected by vibration in either commodity.Agribusiness,

Highly efficient non-degenerate four-wave mixing under dual-mode injection in InP/InAs quantum-dash and quantum-dot lasers at 1.55 μm

This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in Appl. Phys. Lett. 107, 191111 (2015) and may be found at https://doi.org/10.1063/1.4935796.This work reports on non-degenerate four-wave mixing under dual-mode injection in metalorganic vapor phase epitaxy grown InP/InAs quantum-dash and quantum dot Fabry-Perot laser operating at 1550 nm. High values of normalized conversion efficiency of −18.6 dB, optical signal-to-noise ratio of 37 dB, and third order optical susceptibility normalized to material gain χ(3)/g0 of ∼4 × 10−19 m3/V3 are measured for 1490 μm long quantum-dash lasers. These values are similar to those obtained with distributed-feedback lasers and semiconductor optical amplifiers, which are much more complicated to fabricate. On the other hand, due to the faster gain saturation and enhanced modulation of carrier populations, quantum-dot lasers demonstrate 12 dB lower conversion efficiency and 4 times lower χ(3)/g0 compared to quantum dash lasers.DFG, 43659573, SFB 787: Halbleiter - Nanophotonik: Materialien, Modelle, BauelementeEC/FP7/EU/264687/Postgraduate Research on Photonics as an Enabling Technology/PROPHE