211 research outputs found
Second harmonic generation from plasmonic hotspots by controlled local symmetry breaking
Bonding resonant modes of plasmonic nanoantennas with narrow gaps exhibit
very large local field enhancement. These hotspots are highly attractive for
boosting optical nonlinearities, such as second harmonic generation. However,
for resonant symmetric gap antennas, the strong second harmonic sources created
at the gap interfaces oscillate out-of-phase and therefore interfere
destructively in the far-field. Here, we use an advanced nanofabrication
approach to systematically break the local symmetry of nanoscopic antenna gaps
while retaining the bonding resonant antenna mode at the fundamental frequency
and the concomitant intensity hotspot. We find that antennas with the strongest
local symmetry breaking emit correspondingly intense second harmonic radiation
as compared to symmetric reference structures. By combining these findings with
second harmonic radiation patterns as well as quantitative nonlinear
simulations, we obtain remarkably detailed insights into the mechanism of
second harmonic generation at the nanoscale. Our findings open new perspectives
for the realization of non-reciprocal nanoscale systems, where local symmetry
breaking is crucial to create unique functionalities
Variety-depending susceptibility of cherries to Drosophila suzukii according to fruit firmness and other ripening parameters
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Depression predicts revascularization procedures for 5 years after coronary angiography.
OBJECTIVE:Depression has been reported to increase cardiac event rates and functional impairment in patients with coronary disease. This article describes the impact of depression on subsequent healthcare utilization for such patients. METHODS:One hundred ninety-eight health maintenance organization patients with stable coronary disease were interviewed after elective angiography using a structured psychiatric diagnostic scale. Cardiac events, hospitalizations, procedures, and costs were monitored for the next 5 years through automated data. Subjects were classified at the time of angiography by modified DSM-IV criteria into those with major, minor, and no depression. RESULTS:In univariate analyses, the no depression group (N = 136) was most likely to receive coronary artery bypass grafting (CABG) (61% vs. 36% in the major depression group vs. 27% in the minor depression group, p =.001), and the major depression group (N = 25) was most likely to receive percutaneous transluminal coronary angioplasty (PTCA) (44% vs. 14% in the minor depression group vs. 24% in the no depression group). The minor depression group (N = 37) was least likely to be hospitalized for cardiac reasons during follow-up (54% vs. 80% in the major depression group vs. 80% in the no depression group, p =.005). Five-year rates of myocardial infarction and death did not differ significantly between groups. Proportional hazard models showed that those in the depression groups differed in time from catheterization to CABG (chi2(2) = 11.9, p =.003) and time to PCTA (chi2(2) = 7.74, p =.02) after controlling for relevant covariates. Median regression showed that patients with no depression had higher costs during the first year but tended to have lower costs in years 2 through 5 than patients with minor or major depression. CONCLUSIONS:Depression status at angiography is associated with the need for revascularization and total healthcare costs for the following year
Evidence for cascaded third harmonic generation in non-centrosymmetric gold nanoantennas
The optimization of nonlinear optical processes at the nanoscale is a crucial
step for the development of nanoscale photon sources for quantum-optical
networks. The development of innovative plasmonic nanoantenna designs and
hybrid nanostructures to enhance optical nonlinearities in very small volumes
represents one of the most promising routes. In such systems, the upconversion
of photons can be achieved with high efficiencies via third-order processes,
such as third harmonic generation (THG), thanks to the resonantly-enhanced
volume currents. Conversely, second-order processes, such as second harmonic
generation (SHG), are often inhibited by the symmetry of metal lattices and of
common nanoantenna geometries. SHG and THG processes in plasmonic
nanostructures are generally treated independently, since they both represent a
small perturbation in the light-matter interaction mechanisms. In this work, we
demonstrate that this paradigm does not hold in general, by providing evidence
of a cascaded process in THG, which is fueled by SHG and sizably contributes to
the overall yield. We address this mechanism by unveiling an anomalous
fingerprint in the polarization state of the nonlinear emission from
non-centrosymmetric gold nanoantennas and point out that such cascaded
processes may also appear for structures that exhibit only moderate SHG yields
- signifying its general relevance in plasmon-enhanced nonlinear optics. The
presence of this peculiar mechanism in THG from plasmonic nanoantennas at
telecommunication wavelengths allows gaining further insight on the physics of
plasmon-enhanced nonlinear optical processes. This could be crucial in the
realization of nanoscale elements for photon conversion and manipulation
operating at room-temperature.Comment: 25 pages, 4 figure
Single versus double field rate: Do different rates of fenoxycarb in chronic Oomen bee brood feeding tests cause different effects sizes?
Background: EFSA (2013) recommends to modify the Oomen bee brood feeding test (Oomen et al., 19922) from an acute to a chronic feeding test, but proposals regarding the concentration of the reference item fenoxycarb in such trials are missing. For the chronic Oomen bee brood feeding ring-test (see Lückmann & Schmitzer 2014) the double field rate was used. Due to the lack of information about the effect size of the single field rate two separate bee brood feeding tests (following the method given by the ring-test protocol) were conducted: one in July 2013 (study 1) and one in April 2014 (study 2). The single and the double field rate of fenoxycarb were applied each at both times. As endpoints effects on brood termination rate (BTR) of marked eggs, young and old larvae, pupal mortality and colony development (i.e. number of brood cells and colony strength) were recorded and evaluated.Results: The chronic administration of the double field rate caused reproducible results whereas those of the single field rate were more variable. Distinct (i.e. ≥ 50%) and statistically significant increased BTRs of eggs were observed for the single rate in study 2 only, and for the double rate in both studies. Pupal mortality was statistically significantly increased at both rates in both studies and also bee brood and colony strength development was affected at both rates in both studies. Distinct dose-related differences between the two test rates were present for the BTRs of eggs in study 1 and for pupal mortality and colony development in study 2.Conclusion: The chronic feeding of the single rate of fenoxycarb did not cause reproducible, doserelated effects. Therefore it is recommend using the double field rate of fenoxycarb as the toxic reference item dose in chronic Oomen bee brood feeding studies as long as no further data are available on the effect size of the single rate.Keywords: honeybees, chronic Oomen bee brood feeding test, fenoxycarb, single rate, double rat
Measuring single cell mass, volume, and density with dual suspended microchannel resonators
Cell size, measured as either volume or mass, is a fundamental indicator of cell state. Far more tightly regulated than size is density, the ratio between mass and volume, which can be used to distinguish between cell populations even when volume and mass appear to remain constant. Here we expand upon a previous method for measuring cell density involving a suspended microchannel resonator (SMR). We introduce a new device, the dual SMR, as a high-precision instrument for measuring single-cell mass, volume, and density using two resonators connected by a serpentine fluidic channel. The dual SMR designs considered herein demonstrate the critical role of channel geometry in ensuring proper mixing and damping of pressure fluctuations in microfluidic systems designed for precision measurement. We use the dual SMR to compare the physical properties of two well-known cancer cell lines: human lung cancer cell H1650 and mouse lymphoblastic leukemia cell line L1210.National Cancer Institute (U.S.) (Koch Institute Support (Core) Grant P30-CA14051)National Cancer Institute (U.S.). Physical Sciences Oncology Center (U54CA143874)National Cancer Institute (U.S.). Cell Decision Process Center (P50GM68762)National Institutes of Health (U.S.) (Contract R01GM085457
Presentation - Dossier indigenous people and COVID-19: indigenous experiences of the pandemic in Latin America
Se trata de la Presentación al Dossier pueblos originarios y COVID-19: experiencias indÃgenas frente a la pandemia en América Latina, en donde se conjugan artÃculos de académicos/as de Latinoamérica sobre el impacto de la pandemia en diversos pueblos indÃgenas.Fil: Engelman, Juan Manuel. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Universidad de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de FilosofÃa y Letras; Argentina. Universidad Nacional de Lujan. Rectorado.; ArgentinaFil: Schmidt, Mariana Andrea. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Universidad de Buenos Aires; Argentina. Universidad de Buenos Aires; Argentina. Universidad de Buenos Aires. Facultad de Ciencias Sociales. Instituto de Investigaciones "Gino Germani"; ArgentinaFil: Hecht, Ana Carolina. Consejo Nacional de Investigaciones CientÃficas y Técnicas. Universidad de Buenos Aires; Argentina. Universidad de Buenos Aires; Argentin
Balanced single-vector co-delivery of VEGF/PDGF-BB improves functional collateralization in chronic cerebral ischemia
The myoblast-mediated delivery of angiogenic genes represents a cell-based approach for targeted induction of therapeutic collateralization. Here, we tested the superiority of myoblast-mediated co-delivery of vascular endothelial growth factor-A (VEGF) together with platelet-derived growth factor-BB (PDGF-BB) on transpial collateralization of an indirect encephalomyosynangiosis (EMS) in a model of chronic cerebral ischemia. Mouse myoblasts expressing a reporter gene alone (empty vector), VEGF, PDGF-BB or VEGF and PDGF-BB through a single bi-cistronic vector (VIP) were implanted into the temporalis muscle of an EMS following permanent ipsilateral internal carotid artery occlusion in adult, male C57BL/6N mice. Over 84 days, myoblast engraftment and gene product expression, hemodynamic impairment, transpial collateralization, angiogenesis, pericyte recruitment and post-ischemic neuroprotection were assessed. By day 42, animals that received PDGF-BB in combination with VEGF (VIP) showed superior hemodynamic recovery, EMS collateralization and ischemic protection with improved pericyte recruitment around the parenchymal vessels and EMS collaterals. Also, supplementation of PDGF-BB resulted in a striking astrocytic activation with intrinsic VEGF mobilization in the cortex below the EMS. Our findings suggest that EMS surgery together with myoblast-mediated co-delivery of VEGF/PDGF-BB may have the potential to serve as a novel treatment strategy for augmentation of collateral flow in the chronically hypoperfused brain
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