Configuring the cancellation of optical near-fields

The characteristic near-field behavior of electromagnetic fields is open to a variety of interpretations. In a classical sense the term 'near-field' can be taken to signify a region, sufficiently close to some primary or secondary source, that the onset of retardation features is insignificant; a quantum theoretic explanation might focus more on the large momentum uncertainty that operates at small distances. Together, both near-field and wave-zone (radiative) features are fully accommodated in a retarded resonance propagation tensor, within which each component individually represents one asymptotic limit - alongside a third term that is distinctly operative at distances comparable to the optical wavelength. The propagation tensor takes different forms according to the level of multipole involved in the signal production and detection. In this presentation the nature and symmetry properties of the retarded propagation tensor are explored with reference to various forms of electric interaction, and it is shown how a suitable arrangement of optical beams can lead to the complete cancellation of near-fields. The conditions for such behavior are fully determined and some important optical trapping applications are discussed

Optically induced multi-particle structures: multi-dimensional energy landscapes

Recent quantum electrodynamical studies on optically induced inter-particle potential energy surfaces have revealed unexpected features of considerable intricacy. The exploitation of these features presents a host of opportunities for the optical fabrication of nanoscale structures, based on the fine control of a variety of attractive and repulsive forces, and the torques that operate on particle pairs. Here we report an extension of these studies, exploring the first detailed potential energy surfaces for a system of three particles irradiated by a polarized laser beam. Such a system is the key prototype for developing generic models of multi-particle complexity. The analysis identifies and characterizes potential points of stability, as well as forces and torques that particles experience as a consequence of the electromagnetic fields, generated by optical perturbations. Promising results are exhibited for the optical fabrication of assemblies of molecules, nanoparticles, microparticles, and colloidal multi-particle arrays. The comprehension of mechanism that is emerging should help determine the fine principles of multi-particle optical assembly

Multiheterodyne Detection and Sampling of Periodically Filtered White Light for Correlations at 20 km of Delay

A frequency comb is used as a set of coherent local oscillators to downconvert and spectrally compress white light that has been periodically filtered by a Fabry-Perot etalon. Multiheterodyne detection allows white light spread across 100 GHz of optical spectrum to be compressed to 5 GHz of radio frequency (RF) bandwidth for electronic sampling on an oscilloscope. Correlations are observed at delays of up to 20 km with a minimum resolution of less than 1 mm. Calculations show that resolution may be easily increased by increasing etalon finesse and frequency comb bandwidth

Carbon dioxide system in the Canary region during October 1995

During the cruise F/S Poseidon 212/3 (September 30-October 8, 1995) determination of carbon system variables was carried out over the section of La Palma-La Graciosa and at the ESTOC station in the Canary Island area. Total alkalinity and pH in the total scale at 25 degreesC were determined at 24 stations from surface to bottom. In this area, the presence of different water masses can be traced by the carbon system variables. NACW is defined by a strong gradient of A(T) and pH from 150 to 750 m. MW is characterised by high values of A(T) and pH between 1000 to 1200 in and AAIW signals are found at around 900 in in the strait between Gran Canaria and Fuerteventura with low A(T), low pH and a maximum of fCO(2). Assuming an atmospheric mean value of fCO(2) of 360 mu atm and an average surface value of 393 +/-7 mu atm, we can conclude that during this cruise this oceanic area tends to release CO2 into the atmosphere, acting as a weak source with a carbon flux towards the atmosphere of +8.0 +/-1.8 mmol.m(-2)d(-1). The saturation levels in the Canary Island area have been found to be higher than 3600 m for calcite and 2700 in for aragonite. The inorganic carbon/organic carbon ratio (IC/OC) varies from 0.07 at 300 m to 0.5 at 3000 m. The IC/OC ratio shows that about a 34% increase in the C-T of the deep water is contributed by the inorganic CaCO3 dissolution. The IC at 300 in is around 7 mu mol kg(-1), increasing with depth to 37.5 mu mol kg(-1) at 3700 m

Measurement of carrier envelope offset frequency for a 10 GHz etalon-stabilized semiconductor optical frequency comb

We report Carrier Envelope Offset (CEO) frequency measurements of a 10 GHz harmonically mode-locked, Fabry-Perot etalon-stabilized, semiconductor optical frequency comb source. A modified multi-heterodyne mixing technique with a reference frequency comb was utilized for the measurement. Also, preliminary results from an attempt at f-2f self-referencing measurement are presented. The CEO frequency was found to be similar to 1.47 GHz for the particular etalon that was used

Optimizing the linearity in high-speed photodiodes

Analog photonic links require high-fidelity, high-speed optical-to-electrical conversion for applications such as radio-over-fiber, synchronization at kilometer-scale facilities, and low-noise electronic signal generation. Photodetector nonlinearity is a particularly vexing problem, causing signal distortion and excess noise, especially in systems utilizing ultrashort optical pulses. Here we show that photodetectors designed for high power handling and high linearity can perform optical-to-electrical conversion of ultrashort optical pulses with unprecedented linearity over a large photocurrent range. We also show that the broadband, complex impedance of the circuit following the photodiode modifies the linearity significantly. By externally manipulating the circuit impedance, we extend the detector's linear range to higher photocurrents, with over 50 dB rejection of amplitude-to-phase conversion for photocurrents up to 40 mA. This represents a 1000-fold improvement over state-of-the-art photodiodes and significantly extends the attainable microwave power by a factor of four. As such, we eliminate the long-standing requirement in ultrashort pulse detection of precise tuning of the photodiode's operating parameters (average photocurrent, bias voltage or temperature) to coincide with a nonlinearity minimum. These results should also apply more generally to reduce nonlinear distortion in a range of other microwave photonics applications

TRANSFORM (Multicenter Experience With Rapid Deployment Edwards INTUITY Valve System for Aortic Valve Replacement) US clinical trial: Performance of a rapid deployment aortic valve

Background: The TRANSFORM (Multicenter Experience With Rapid Deployment Edwards INTUITY Valve System for Aortic Valve Replacement) trial (NCT01700439) evaluated the performance of the INTUITY rapid deployment aortic valve replacement (RDAVR) system in patients with severe aortic stenosis. Methods: TRANSFORM was a prospective, nonrandomized, multicenter (n 1�4 29), single-arm trial. INTUITY is comprised of a cloth-covered balloon- expandable frame attached to a Carpentier-Edwards PERIMOUNT Magna Ease aortic valve. Primary and effectiveness endpoints were evaluated at 1 year. Results: Between 2012 and 2015, 839 patients underwent RDAVR. Mean age was 73.5 8.3 years. Full sternotomy (FS) was used in 59% and minimally invasive surgical incisions in 41%. Technical success rate was 95%. For isolated RDAVR, mean crossclamp and cardiopulmonary bypass times for FS were 49.3 26.9 minutes and 69.2 34.7 minutes, respectively, and for minimally invasive surgical 63.1 25.4 minutes and 84.6 33.5 minutes, respectively. These times were favorable compared with Society of Thoracic Surgeons data- base comparators for FS: 76.3 minutes and 104.2 minutes, respectively, and for minimally invasive surgical, 82.9 minutes and 111.4 minutes, respectively (P<.001). At 30 days, all-cause mortality was 0.8%; valve explant, 0.1%; throm- boembolism, 3.5%; and major bleeding, 1.3%. In patients with isolated aortic valve replacement, the rate of permanent pacemaker implantation was 11.9%. At 1 year, mean effective orifice area was 1.7 cm2; mean gradient, 10.3 mm Hg; and moderate and severe paravalvular leak, 1.2% and 0.4%, respectively

Down-regulation of SFRP1 as a putative tumor suppressor gene can contribute to human hepatocellular carcinoma

<p>Abstract</p> <p>Background</p> <p>Hepatocellular carcinoma (HCC) is one of the most common cancers in the world. SFRP1 (the secreted frizzled-related protein 1), a putative tumor suppressor gene mapped onto chromosome 8p12-p11.1, the frequent loss of heterozygosity (LOH) region in human HCC, encodes a Wingless-type (Wnt) signaling antagonist and is frequently inactivated by promoter methylation in many human cancers. However, whether the down-regulation of SFRP1 can contribute to hepatocarcinogenesis still remains unclear.</p> <p>Methods</p> <p>We investigated the expression of SFRP1 through real time RT-PCR and immunohistochemistry staining. The cell growth and colony formation were observed as the overexpression and knockdown of SFRP1. The DNA methylation status within SFRP1 promoter was analyzed through methylation-specific PCR or bisulphate-treated DNA sequencing assays. Loss of heterozygosity was here detected with microsatellite markers.</p> <p>Results</p> <p>SFRP1 was significantly down-regulated in 76.1% (35/46) HCC specimens at mRNA level and in 30% (30/100) HCCs indicated by immunohistochemistry staining, as compared to adjacent non-cancerous livers. The overexpression of SFRP1 can significantly inhibit the cell growth and colony formation of YY-8103, SMMC7721, and Hep3B cells. The RNA interference against the constitutional SFRP1 in the offspring SMMC7721 cells, which were stably transfected by ectopic SFRP1, can markedly promote cell growth of these cells. LOH of both microsatellite markers D8S532 and D8SAC016868 flanking the gene locus was found in 13% (6 of 46 HCCs) and 6.5% (3 of 46 HCCs) of the informative cases, respectively, where 5 of 8 HCC specimens with LOH showed the down-regulation of SFRP1. DNA hypermethylation within SFRP1 promoter was identified in two of three HCC specimens without SFRP1 expression. Moreover, the DNA methylation of SFRP1 promoter was significantly reduced, along with the re-expression of the gene, in those HCC cell lines, Bel7404, QGY7701, and MHCC-H, as treated by DAC.</p> <p>Conclusion</p> <p>Our data suggested that the down-regulation of SFRP1 as a candidate tumor suppressor gene, triggered by the epigenetic and/or genetic events, could contribute to the oncogenesis of HCC.</p