Broadband enhancement of light emission in silicon slot waveguides

We investigate the light emission properties of electrical dipole emitters inside 2-dimensional (2D) and 3-dimensional (3D) silicon slot waveguides and evaluate the spontaneous emission enhancement (F_p) and waveguide coupling ratio (β). Under realistic conditions, we find that greater than 10-fold enhancement in F_p can be achieved, together with a β as large as 0.95. In contrast to the case of high Q optical resonators, such performance enhancements are obtained over a broad wavelength region, which can cover the entire emission spectrum of popular optical dopants such as Er. The enhanced luminescence efficiency and the strong coupling into a limited set of well-defined waveguide modes enables a new class of power-efficient, CMOS-compatible, waveguide-based light sources

Unravelling the evolution of Africa's drainage basins through a widespread freshwater fish, the African sharptooth catfish Clarias gariepinus

Aim The formation history of Africa's current river basins remains largely unknown. In order to date changes in landscape and climate, we studied the biogeography of the African freshwater fish with the largest natural distribution. We also validated biogeographical units. Location Continental Africa. Taxon Clarias gariepinus sl. Methods We investigated mitochondrial cytb sequences of 443 individuals from 97 localities, using a haplotype network and a genetic landscape analysis. We inferred a dated phylogeny using maximum likelihood and Bayesian inference approaches and reconstructed ancestral areas with S-DEC and S-DIVA models. Microsatellite genotyping complemented the mitochondrial approach in the Congo basin, where the latter revealed complex patterns. Results Limited differentiation is found in northern and south-western Africa, and sharp genetic differentiation in the continent's east and centre. Populations with affinities to neighbouring basins occur at the edges of the Congo province. High diversity exists in the south of the Congo basin. The Zambezi province is partitioned into eastern, central and western sectors. In the east, specimens were related to those from the Congo. In the west, they were similar to Southern representatives. Phylogenetic inference placed the origin of C. gariepinus in the East Coast, with intraspecific diversification starting around the Great Lakes. These events occurred ca. 4.8-1.65 and 2.3-0.8 MYA respectively. Main conclusions Clades of C. gariepinus sl. show a clear geographical signature. The origin of C. gariepinus in the East Coast and diversification around the Great Lakes coincided with the periods of increased aridity. Low genetic differentiation in northern and southern Africa may result from connectivity during recent periods of higher rainfall. In contrast to other widespread African freshwater fish, colonization rather than extinction seemed to mediate distribution patterns. This can be explained by a high ecological tolerance. We highlight the species' suitability to study landscape and climate evolution at various scales.Peer reviewe

On the equivalence of the Langevin and auxiliary field quantization methods for absorbing dielectrics

Recently two methods have been developed for the quantization of the electromagnetic field in general dispersing and absorbing linear dielectrics. The first is based upon the introduction of a quantum Langevin current in Maxwell's equations [T. Gruner and D.-G. Welsch, Phys. Rev. A 53, 1818 (1996); Ho Trung Dung, L. Kn\"{o}ll, and D.-G. Welsch, Phys. Rev. A 57, 3931 (1998); S. Scheel, L. Kn\"{o}ll, and D.-G. Welsch, Phys. Rev. A 58, 700 (1998)], whereas the second makes use of a set of auxiliary fields, followed by a canonical quantization procedure [A. Tip, Phys. Rev. A 57, 4818 (1998)]. We show that both approaches are equivalent.Comment: 7 pages, RevTeX, no figure

Pre-clinical Evaluation of a Cyanine-Based SPECT Probe for Multimodal Tumor Necrosis Imaging

Purpose: Recently we showed that a number of carboxylated near-infrared fluorescent (NIRF) cyanine dyes possess strong necrosis avid properties in vitro as well as in different mouse models of spontaneous and therapy-induced tumor necrosis, indicating their potential use for cancer diagnostic- and prognostic purposes. In the previous study, the detection of the cyanines was achieved by whole body optical imaging, a technique that, due to the limited penetration of near-infrared light, is not suitable for investigations deeper than 1 cm within the human body. Therefore, in order to facilitate clinical translation, the purpose of the present study was to generate a necrosis avid cyanine-based NIRF probe that could also be used for single photon emission computed tomography (SPECT). For this, the necrosis avid NIRF cyanine HQ4 was radiolabeled with 111indium, via the chelate diethylene triamine pentaacetic acid (DTPA). Procedures: The necrosis avid properties of the radiotracer [111In]DTPA-HQ4 were examined in vitro and in vivo in different breast tumor models in mice using SPECT and optical imaging. Moreover, biodistribution studies were performed to examine the pharmacokinetics of the probe in vivo. Results: Using optical imaging and radioactivity measurements, in vitro, we showed selective accumulation of [111In]DTPA-HQ4 in dead cells. Using SPECT and in biodistribution studies, the necrosis avidity of the radiotracer was confirmed in a 4T1 mouse breast cancer model of spontaneous tumor necrosis and in a MCF-7 human breast cancer model of chemotherapy-induced tumor necrosis. Conclusions: The radiotracer [111In]DTPA-HQ4 possessed strong and selective necrosis avidity in vitro and in various mouse models of tumor necrosis in vivo, indicating its potential to be clinically applied for diagnostic purposes and to monitor anti-cancer treatment efficacy

Electrical Control of Optical Emitter Relaxation Pathways enabled by Graphene

Controlling the energy flow processes and the associated energy relaxation rates of a light emitter is of high fundamental interest, and has many applications in the fields of quantum optics, photovoltaics, photodetection, biosensing and light emission. While advanced dielectric and metallic systems have been developed to tailor the interaction between an emitter and its environment, active control of the energy flow has remained challenging. Here, we demonstrate in-situ electrical control of the relaxation pathways of excited erbium ions, which emit light at the technologically relevant telecommunication wavelength of 1.5 $\mu$m. By placing the erbium at a few nanometres distance from graphene, we modify the relaxation rate by more than a factor of three, and control whether the emitter decays into either electron-hole pairs, emitted photons or graphene near-infrared plasmons, confined to $<$15 nm to the sheet. These capabilities to dictate optical energy transfer processes through electrical control of the local density of optical states constitute a new paradigm for active (quantum) photonics.Comment: 9 pages, 4 figure

Development of a value-based healthcare burns core set for adult burn care

Background: Value-based healthcare (VBHC) is increasingly implemented in healthcare worldwide. Transparent measurement of the outcomes most important and relevant to patients is essential in VBHC, which is supported by a core set of most important quality indicators and outcomes. Therefore, the aim of this study was to develop a VBHC-burns core set for adult burn patients. Methods: A three-round modified national Delphi study, including 44 outcomes and 24 quality indicators, was conducted to reach consensus among Dutch patients, burn care professionals and researchers. Items were rated on a nine-point Likert scale and selected if ≥ 70% in each group considered an item ‘important’. Subsequently, instruments quantifying selected outcomes were identified based on a literature review and were chosen in a consensus meeting using recommendations from the Dutch consensus-based standard set and the Dutch Centre of Expertise on Health Disparities. Time assessment points were chosen to reflect the burn care and patient recovery process. Finally, the initial core set was evaluated in practice, leading to the adapted VBHC-burns core set. Results: Twenty-seven patients, 63 burn care professionals and 23 researchers participated. Ten outcomes and four quality indicators were selected in the Delphi study, including the outcomes pain, wound healing, physical activity, self-care, independence, return to work, depression, itching, scar flexibility and return to school. Quality indicators included shared decision-making (SDM), the number of patients receiving aftercare, determination of burn depth, and assessment of active range of motion. After evaluation of its use in clinical practice, the core set included all items except SDM, which are assessed by 9 patient-reported outcome instruments or measured in clinical care. Assessment time points included are at discharge, 2 weeks, 3 months, 12 months after discharge and annually afterwards. Conclusion: A VBHC-burns core set was developed, consisting of outcomes and quality indicators that are important to burn patients and burn care professionals. The VBHC-burns core set is now systemically monitored and analysed in Dutch burn care to improve care and patient relevant outcomes. As improving burn care and patient relevant outcomes is important worldwide, the developed VBHC-burns core set could be inspiring for other countries.</p

Dual-Wavelength Imaging of Tumor Progression by Activatable and Targeting Near-Infrared Fluorescent Probes in a Bioluminescent Breast Cancer Model

Bioluminescence imaging (BLI) has shown its appeal as a sensitive technique for in vivo whole body optical imaging. However, the development of injectable tumor-specific near-infrared fluorescent (NIRF) probes makes fluorescence imaging (FLI) a promising alternative to BLI in situations where BLI cannot be used or is unwanted (e.g., spontaneous transgenic tumor models, or syngeneic mice to study immune effects)

Marine Incursion: The Freshwater Herring of Lake Tanganyika Are the Product of a Marine Invasion into West Africa

The spectacular marine-like diversity of the endemic fauna of Lake Tanganyika, the oldest of the African Great Lakes, led early researchers to suggest that the lake must have once been connected to the ocean. Recent geophysical reconstructions clearly indicate that Lake Tanganyika formed by rifting in the African subcontinent and was never directly linked to the sea. Although the Lake has a high proportion of specialized endemics, the absence of close relatives outside Tanganyika has complicated phylogeographic reconstructions of the timing of lake colonization and intralacustrine diversification. The freshwater herring of Lake Tanganyika are members of a large group of pellonuline herring found in western and southern Africa, offering one of the best opportunities to trace the evolutionary history of members of Tanganyika's biota. Molecular phylogenetic reconstructions indicate that herring colonized West Africa 25–50MYA, at the end of a major marine incursion in the region. Pellonuline herring subsequently experienced an evolutionary radiation in West Africa, spreading across the continent and reaching East Africa's Lake Tanganyika during its early formation. While Lake Tanganyika has never been directly connected with the sea, the endemic freshwater herring of the lake are the descendents of an ancient marine incursion, a scenario which may also explain the origin of other Tanganyikan endemics