Natural variation reveals that intracellular distribution of ELF3 protein is associated with function in the circadian clock

Natural selection of variants within the Arabidopsis thaliana circadian clock can be attributed to adaptation to varying environments. To define a basis for such variation, we examined clock speed in a reporter-modified Bay-0 x Shakdara recombinant inbred line and localized heritable variation. Extensive variation led us to identify EARLY FLOWERING3 (ELF3) as a major quantitative trait locus (QTL). The causal nucleotide polymorphism caused a short-period phenotype under light and severely dampened rhythm generation in darkness, and entrainment alterations resulted. We found that ELF3-Sha protein failed to properly localize to the nucleus, and its ability to accumulate in darkness was compromised. Evidence was provided that the ELF3-Sha allele originated in Central Asia. Collectively we showed that ELF3 protein plays a vital role in defining its light-repressor action in the circadian clock and that its functional abilities are largely dependent on its cellular localization

Advancing Evaluation Practices in Philanthropy

In recent years, the philanthropic sector has neared consensus on the need to improve measurement and evaluation of its work. Although the philanthropies they lead use different methods, members of the Aspen Philanthropy Group (APG) have agreed that basic principles and practices can inform efforts to monitor performance, track progress, and assess the impact of foundation strategies, initiatives, and grants. They hope to build a culture of learning in the process

Observation of Spin Relaxation Anisotropy in Semiconductor Quantum Wells

Spin relaxation of two-dimensional electrons in asymmetrical (001) AlGaAs quantum wells are measured by means of Hanle effect. Three different spin relaxation times for spins oriented along [110], [1-10] and [001] crystallographic directions are extracted demonstrating anisotropy of D'yakonov-Perel' spin relaxation mechanism. The relative strengths of Rashba and Dresselhaus terms describing the spin-orbit coupling in semiconductor quantum well structures. It is shown that the Rashba spin-orbit splitting is about four times stronger than the Dresselhaus splitting in the studied structure.Comment: 4 pages, 3 figure

Spin relaxation in (110) and (001) InAs/GaSb superlattices

We report an enhancement of the electron spin relaxation time (T1) in a (110) InAs/GaSb superlattice by more than an order of magnitude (25 times) relative to the corresponding (001) structure. The spin dynamics were measured using polarization sensitive pump probe techniques and a mid-infrared, subpicosecond PPLN OPO. Longer T1 times in (110) superlattices are attributed to the suppression of the native interface asymmetry and bulk inversion asymmetry contributions to the precessional D'yakonov Perel spin relaxation process. Calculations using a nonperturbative 14-band nanostructure model give good agreement with experiment and indicate that possible structural inversion asymmetry contributions to T1 associated with compositional mixing at the superlattice interfaces may limit the observed spin lifetime in (110) superlattices. Our findings have implications for potential spintronics applications using InAs/GaSb heterostructures.Comment: 4 pages, 2 figure

Spin- and energy relaxation of hot electrons at GaAs surfaces

The mechanisms for spin relaxation in semiconductors are reviewed, and the mechanism prevalent in p-doped semiconductors, namely spin relaxation due to the electron-hole exchange interaction, is presented in some depth. It is shown that the solution of Boltzmann-type kinetic equations allows one to obtain quantitative results for spin relaxation in semiconductors that go beyond the original Bir-Aronov-Pikus relaxation-rate approximation. Experimental results using surface sensitive two-photon photoemission techniques show that the spin relaxation-time of electrons in p-doped GaAs at a semiconductor/metal surface is several times longer than the corresponding bulk spin relaxation-times. A theoretical explanation of these results in terms of the reduced density of holes in the band-bending region at the surface is presented.Comment: 33 pages, 12 figures; earlier submission replaced by corrected and expanded version; eps figures now included in the tex

Reach Extension and Capacity Enhancement of VCSEL-Based Transmission Over Single-Lane MMF Links

This paper reviews and examines several techniques for expanding the carrying capacity of multimode fiber (MMF) using vertical cavity surface emitting lasers (VCSELs). The first approach utilizes short wavelength division multiplexing in combination with MMF optimized for operation between 850 and 950 nm. Both nonreturn to zero (NRZ) and four-level pulse amplitude modulation (PAM4) signaling are measured and demonstrate up to 170-Gb/s postforward error correction transmission over 300 m. For single wavelength transmission, the use of selective modal launch to increase the optical bandwidth of a standard OM3 MMF to more than 2.1 GHzkm for standard MMF is presented. A statistical model is used to predict the bandwidth enhancement of installed MMF and indicates that significant link extension can be achieved using selective modal launch techniques. These results demonstrate the continued effectiveness of VCSEL-based MMF links in current and future data center environments

European economic constitution and the transformation of democracy : on class and the state of law

In the context of contemporary analyses of the Europe Union as a post-democratic form of economic governance, this article explores the (ordo)liberal character of monetary union as a regime of imposed liberty. The argument holds that rather than forcing the member states into retreat, the economic constitution of Europe strengthens their liberal foundation, securing their utility as the organised force of a mode of social reproduction founded on free labour. It develops the character of the liberal state as the political form of a free market economy with reference to Adam Smith’s classical political economy and the German ordoliberal tradition, which calls for a rule-based system of federated forms of economic governance to secure a free labour economy in conditions of mass democratic aspirations for a freedom from want. It explores the rationale of the ordoliberal distinction between the liberal character and the democratic character of the state and, in this context, assesses the meaning of liberal democracy in a post-democratic Eurozone