An exciton-polariton laser based on biologically produced fluorescent protein

We thank A. Clemens (TU Dresden, Germany) for technical support with protein preparation and C. Murawski (U St Andrews, UK) for support with TDAF deposition. We acknowledge support from the ERC Starting Grant ABLASE (640012), the Scottish Funding Council (via SUPA), the European Union Marie Curie Career Integration Grant (PCIG12-GA-2012-334407), studentship funding through the EPSRC CM-DTC (EP/L015110/1) and the EPSRC Hybrid Polaritonics program grant (EP/M025330/1). S.H. gratefully acknowledges support by the Royal Society and the Wolfson Foundation and M.S. gratefully acknowledges support from a MSCA IF (659213).Under adequate conditions, cavity-polaritons form a macroscopic coherent quantum state, known as polariton condensate (PC). Compared to Wannier-Mott polaritons in inorganic semiconductors, the localized Frenkel polaritons in organic emitter materials show weaker interaction with each other but stronger coupling to light, which recently enabled the first realization of a PC at room temperature. However, this required ultrafast optical pumping which limits the applications of organic PCs. Here, we demonstrate room-temperature PCs of cavity-polaritons in simple laminated microcavities filled with the biologically produced enhanced green fluorescent protein (eGFP). The unique molecular structure of eGFP prevents exciton annihilation even at high excitation densities, thus facilitating PCs under conventional nanosecond pumping. Condensation is clearly evidenced by a distinct threshold, an interaction-induced blueshift of the condensate, long-range coherence and the presence of a second threshold at higher excitation density which is associated with the onset of photon lasing.Publisher PDFPeer reviewe

Bulk AlInAs on InP(111) as a novel material system for pure single photon emission

In this letter, we report on quantum light emission from bulk AlInAs grown on InP(111) substrates. We observe indium rich clusters in the bulk Al0:48In0:52As (AlInAs), resulting in quantum dot-like energetic traps for charge carriers, which are confirmed via cross-sectional scanning tunnelling microscopy (XSTM) measurements and 6-band k•p simulations. We observe quantum dot (QD)-like emission signals, which appear as sharp lines in our photoluminescence spectra at near infrared wavelengths around 860 nm, and with linewidths as narrow as 50 meV. We demonstrate the capability of this new material system to act as an emitter of pure single photons as we extract g(2)-values as low as g(2)/cw (0) = 0:05+0:17/-0:05 for continuous wave (cw) excitation and g (2) pulsed, corr. = 0:24 ± 0:02 for pulsed excitation.PostprintPeer reviewe

Integration of IEEE C37.118 and publish/subscribe communication

IEEE C37.118 is the current standard for synchrophasor measurements in power systems. It defines the measurement method and communication protocols for the entities in a synchrophasor network. The standard offers two different modes for client-server communication, but cannot be used unchanged over publish/subscribe communication architectures, whose major advantage is simplified and incremental integration of new applications. This work reviews the communication part of IEEE C37.118, and provides an adapter-based solution to easily connect and integrate entities in a synchrophasor network over a publish/subscribe communication architecture. The proposed adapters offer standard-compliant communication between the synchrophasor measurement network entities to facilitate the exchange of measurement data

Social comparison processes in organizations

We systematically analyze the role of social comparison processes in organizations. Specifically, we describe how social comparison processes have been used to explain six key areas of organizational inquiry: (1) organizational justice, (2) performance appraisal, (3) virtual work environments, (4) affective behavior in the workplace, (5) stress, and (6) leadership. Additionally, we describe how unique contextual factors in organizations offer new insight into two widely studied sub-processes of social comparison, acquiring social information and thinking about that information. Our analyses underscore the merit of integrating organizational phenomena and social comparison processes in future research and theory

Single-mode interband cascade lasers emitting below 2.8 μm

Financial support by the European Commission within the WideLase Seventh Framework Programme Project (Grant Agreement No.: 318798) is gratefully acknowledged.In this work, single-mode distributed feedback (DFB) interband cascade laser (ICL) devices with record short wavelength emission below 2.8 μm are presented. Pulsed measurements based on broad area laser devices with a cavity of 2 mm length and 150 μm width showed threshold current densities of 383 A/cm2 at T = 20 °C and a characteristic temperature T0 of 67 K. Fabricated DFB devices were operated in continuous wave mode at room temperature, with threshold currents of 57 mA and demonstrated side mode suppression ratios of larger than 25 dB. The devices showed current tuning ranges of 7 nm and total (including drive current and temperature) tuning ranges of 12 nm, with respective tuning rates of 21 nm/W, 0.13 nm/mA and 0.29 nm/K. Using the full spectral gain bandwidth of the underlying ICL material, single-mode DFB emission was observed within a wavelength range of 150 nm utilizing different DFB grating periods.Publisher PDFPeer reviewe

A novel compound heterozygous leptin receptor mutation causes more severe obesity than in Lepr(db/db) mice

The leptin receptor (Lepr) pathway is important for food intake regulation, energy expen-diture, and body weight. Mutations in leptin and the Lepr have been shown to cause early-onset severe obesity in mice and humans. In studies with C57BL/ 6NCrl mice, we found a mouse with extreme obesity. To identify a putative spontaneous new form of monogenic obesity, we performed backcross studies with this mouse followed by a quantitative trait locus (QTL) analysis and sequencing of the selected chro-mosomal QTL region. We thereby identified a novel Lepr mutation (C57BL/6N-Lepr(L536Hfs*6-1NKB)), which is located at chromosome 4, exon 11 within the CRH2-leptin-binding site. Compared with C57BL/6N mice, Lepr(L536Hfs*6) develop early onset obesity and their body weight exceeds that of Leprdb/db mice at an age of 30 weeks. Similar to Leprdb/db mice, the Lepr(L536Hfs*6) model is characterized by hyperphagia, obesity, lower energy expenditure and activity, hyperglycemia, and hyperinsulinemia compared with C57BL/6N mice. Crossing Leprdb/wt with Lepr(L536Hfs*6/wt) mice results in compound heterozygous Lepr(L536Hfs*6/db) mice, which develop even higher body weight and fat mass than both homozygous Lepr(db/db) and Lepr(L536Hfs*6) mice. Compound heterozygous Lepr deficiency affecting functionally different regions of the Lepr causes more severe obesity than the parental homozygous mutations.Peer reviewe

Early changes in hippocampal neurogenesis in transgenic mouse models for Alzheimer's disease

Alzheimer's disease (AD) is the most prevalent neurodegenerative disease in the Western world and is characterized by a progressive loss of cognitive functions leading to dementia. One major histopathological hallmark of AD is the formation of amyloid-beta plaques, which is reproduced in numerous transgenic animal models overexpressing pathogenic forms of amyloid precursor protein (APP). In human AD and in transgenic amyloid plaque mouse models, several studies report altered rates of adult neurogenesis, i.e. the formation of new neurons from neural stem and progenitor cells, and impaired neurogenesis has also been attributed to contribute to the cognitive decline in AD. So far, changes in neurogenesis have largely been considered to be a consequence of the plaque pathology. Therefore, possible alterations in neurogenesis before plaque formation or in prodromal AD have been largely ignored. Here, we analysed adult hippocampal neurogenesis in amyloidogenic mouse models of AD at different points before and during plaque progression. We found prominent alterations of hippocampal neurogenesis before plaque formation. Survival of newly generated cells and the production of new neurons were already compromised at this stage. Moreover and surprisingly, proliferation of doublecortin (DCX) expressing neuroblasts was significantly and specifically elevated during the pre-plaque stage in the APP-PS1 model, while the Nestin-expressing stem cell population was unaffected. In summary, changes in neurogenesis are evident already before plaque deposition and might contribute to well-known early hippocampal dysfunctions in prodromal AD such as hippocampal overactivity

Data underpinning - An exciton-polariton laser based on biologically produced fluorescent protein

The attached data underpin the publication, "An exciton-polariton laser based on biologically produced fluorescent protein". Data for each figure panel from the paper that displays numerical data are provided in the form of either tagged image format file (.tif) or as ASCII text-formatted data (.txt)