3,228 research outputs found
Enhanced photoluminescence emission from two-dimensional silicon photonic crystal nanocavities
We present a temperature dependent photoluminescence study of silicon optical
nanocavities formed by introducing point defects into two-dimensional photonic
crystals. In addition to the prominent TO phonon assisted transition from
crystalline silicon at ~1.10 eV we observe a broad defect band luminescence
from ~1.05-1.09 eV. Spatially resolved spectroscopy demonstrates that this
defect band is present only in the region where air-holes have been etched
during the fabrication process. Detectable emission from the cavity mode
persists up to room-temperature, in strong contrast the background emission
vanishes for T > 150 K. An Ahrrenius type analysis of the temperature
dependence of the luminescence signal recorded either in-resonance with the
cavity mode, or weakly detuned, suggests that the higher temperature stability
may arise from an enhanced internal quantum efficiency due to the
Purcell-effect
A Correlation between the Emission Intensity of Self-Assembled Germanium Islands and the Quality Factor of Silicon Photonic Crystal Nanocavities
We present a comparative micro-photoluminescence study of the emission
intensity of self-assembled germanium islands coupled to the resonator mode of
two-dimensional silicon photonic crystal defect nanocavities. The emission
intensity is investigated for cavity modes of L3 and Hexapole cavities with
different cavity quality factors. For each of these cavities many nominally
identical samples are probed to obtain reliable statistics. As the quality
factor increases we observe a clear decrease in the average mode emission
intensity recorded under comparable optical pumping conditions. This clear
experimentally observed trend is compared with simulations based on a
dissipative master equation approach that describes a cavity weakly coupled to
an ensemble of emitters. We obtain evidence that reabsorption of photons
emitted into the cavity mode is responsible for the observed trend. In
combination with the observation of cavity linewidth broadening in power
dependent measurements, we conclude that free carrier absorption is the
limiting effect for the cavity mediated light enhancement under conditions of
strong pumping.Comment: 8 pages, 5 figure
Outer- to inner-shelf response to stepped sea-level rise: Insights from incised valleys and submerged shorelines
Potential drug-drug interactions in patients with indication for prophylactic implantation of a cardioverter defibrillator: a cross-sectional analysis
Background: Due to demographic transition, multimorbidity and high numbers of medicinal products, polypharmacy rates will presumably further increase. This could lead to higher risks of potentially inappropriate medications with potential drug-drug interactions (PDDI). PDDI has already been investigated by several studies, but not for patients with indication for prophylactic implantation of a cardioverter defibrillator (ICD). Thus, the objective of this analysis was to examine the frequency of PDDI in that specific group of patients and compare patients with or without PDDI regarding potential underlying factors.
Methods: Cross-sectional data analyses were performed using data of the prospective EU-CERT-ICD study that primarily aimed to assess ICD effectiveness in Europe. Self-reported baseline medication data of patients from Germany and Switzerland were used. Patients who reported to take at least two drugs simultaneously for at least 80 days were defined as population at risk. By means of a publicly available interaction checker, we analyzed the medication data regarding occurrence and characteristics of PDDI categorized as minor, moderate, and major PDDI. The analyses were done using descriptive methods and chi square testing.
Results: The total population (n = 524) and the population at risk (n = 383) were rather similar with an average age of 64 years and about 80% male. PDDIs were found for 296 patients (in 57% of total population vs. 77% of population at risk). The moderate PDDI category was most frequently with 268 affected patients. Comparing patients with and without any PDDI, the proportion of patients with place of residence in Germany varied distinctly (93% vs. 78%). The frequency of any PDDI for the total population was twice as high in Germany as in Switzerland (p value < 0.001).
Conclusions: PDDIs were frequently observed in this selected patient population and differed markedly between German and Swiss patients. The results should lead to higher awareness of polypharmacy and PDDIs. Adequate cooperation between health care providers should be promoted and new technologies such as drug interaction information systems or digital patient files used.
Trial registration: The EU-CERT-ICD study is registered at www.clinicaltrials.gov (NCT02064192)
Guide to Common Parasites of Food Fish Species in the Northwest Territories and Nunavut
Global Water Futures supported by the Canada First Research Excellence FundNon-Peer ReviewedPrepared by N. Zabel & Dr. H. Swanson, Wilfrid Laurier University, and reviewed by
Dr. G. Conboy (DVM, PhD, DACVM), Atlantic Veterinary College, University of
Prince Edward Island. Preparation of this guide was supported by Northern Water
Futures (Global Water Futures; Canada First Research Excellence Fund). Reviews,
photographs, and expert guidance was received as in-kind support from several
individuals, and we gratefully acknowledge these important contributions.
Funding for printing of guides distributed within Northwest Territories was provided by Government of Northwest Territories
Integrating Plant Science and Crop Modeling: Assessment of the Impact of Climate Change on Soybean and Maize Production
Increasing global CO₂ emissions have profound consequences for plant biology, not least because of direct influences on carbon gain. However, much remains uncertain regarding how our major crops will respond to a future high CO₂ world. Crop model inter-comparison studies have identified large uncertainties and biases associated with climate change. The need to quantify uncertainty has drawn the fields of plant molecular physiology, crop breeding and biology, and climate change modeling closer together. Comparing data from different models that have been used to assess the potential climate change impacts on soybean and maize production, future yield losses have been predicted for both major crops. When CO2 fertilization effects are taken into account significant yield gains are predicted for soybean, together with a shift in global production from the Southern to the Northern hemisphere. Maize production is also forecast to shift northwards. However, unless plant breeders are able to produce new hybrids with improved traits, the forecasted yield losses for maize will only be mitigated by agro-management adaptations. In addition, the increasing demands of a growing world population will require larger areas of marginal land to be used for maize and soybean production. We summarize the outputs of crop models, together with mitigation options for decreasing the negative impacts of climate on the global maize and soybean production, providing an overview of projected land-use change as a major determining factor for future global crop production
Accurate strain measurements in highly strained Ge microbridges
Ge under high strain is predicted to become a direct bandgap semiconductor.
Very large deformations can be introduced using microbridge devices. However,
at the microscale, strain values are commonly deduced from Raman spectroscopy
using empirical linear models only established up to 1.2% for uniaxial stress.
In this work, we calibrate the Raman-strain relation at higher strain using
synchrotron based microdiffraction. The Ge microbridges show unprecedented high
tensile strain up to 4.9 % corresponding to an unexpected 9.9 cm-1 Raman shift.
We demonstrate experimentally and theoretically that the Raman strain relation
is not linear and we provide a more accurate expression.Comment: 10 pages, 4 figure
Experimental Observation of the Inverse Proximity Effect in Superconductor/Ferromagnet Layered Structures
We have studied the nuclear magnetic resonance (NMR) of 51V nuclei in the
superconductor/ferromagnet thin film heterostructures Ni/V/Ni and
Pd{1-x}Fe{x}/V/Pd{1-x}Fe{x} in the normaland superconducting state. Whereas the
position and shape of the NMR line in the normal state for the trilayers is
identical to that observed in a single V-layer, in the superconducting state
the line shape definitely changes, developing a systematic distortion of the
high-field wing of the resonance line. We consider this as the first
experimental evidence for the penetration of ferromagnetism into the
superconducting layer, a phenomenon which has been theoretically predicted
recently and dubbed the inverse proximity effect.Comment: about 5 pages, 3 figures, 1 tabl
Sediment accumulation and carbon burial in four hadal trench systems
Hadal trenches are considered to act as depocenters for organic material, although pathways for the material transport and deposition rates are poorly constrained. Here we assess focusing, deposition and accumulation of material and organic carbon in four hadal trench systems underlying different surface ocean productivities; the eutrophic Atacama and Kuril-Kamchatka trenches, the mesotrophic Kermadec trench and the oligotrophic Mariana Trench. The study is based on the distributions of naturally occurring 210Pbex, 137Cs and total organic carbon from recovered sediment cores and by applying previously quantified benthic mineralization rates. Periods of steady deposition and discreet mass-wasting deposits were identified from the profiles and the latter were associated with historic recorded seismic events in the respective regions. During periods without mass wasting, the estimated focusing factors along trench axes were elevated, suggesting more or less continuous downslope focusing of material toward the interior of the trenches. The estimated organic carbon deposition rates during these periods exhibited extensive site-specific variability, but were generally similar to values encountered at much shallower settings such as continental slopes and margins. Organic carbon deposition rates during periods of steady deposition were not mirrored by surface ocean productivity, but appeared confounded by local bathymetry. The inclusion of deposition mediated by mass-wasting events enhanced the sediment and organic carbon accumulations for the past ∼ 150 years by up to a factor of ∼ 4. Thus, due to intensified downslope material focusing and infrequent mass-wasting events, hadal trenches are important sites for deposition and sequestration of organic carbon in the deep sea
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