Efficient unidirectional nanoslit couplers for surface plasmons

Plasmonics is based on surface plasmon polariton (SPP) modes which can be laterally confined below the diffraction limit, thereby enabling ultracompact optical components. In order to exploit this potential, the fundamental bottleneck of poor light-SPP coupling must be overcome. In established SPP sources (using prism, grating} or nanodefect coupling) incident light is a source of noise for the SPP, unless the illumination occurs away from the region of interest, increasing the system size and weakening the SPP intensity. Back-side illumination of subwavelength apertures in optically thick metal films eliminates this problem but does not ensure a unique propagation direction for the SPP. We propose a novel back-side slit-illumination method based on drilling a periodic array of indentations at one side of the slit. We demonstrate that the SPP running in the array direction can be suppressed, and the one propagating in the opposite direction enhanced, providing localized unidirectional SPP launching.Comment: 13 pages, 4 figure

Spatial Pyramid Pooling in Deep Convolutional Networks for Visual Recognition

Existing deep convolutional neural networks (CNNs) require a fixed-size (e.g., 224x224) input image. This requirement is "artificial" and may reduce the recognition accuracy for the images or sub-images of an arbitrary size/scale. In this work, we equip the networks with another pooling strategy, "spatial pyramid pooling", to eliminate the above requirement. The new network structure, called SPP-net, can generate a fixed-length representation regardless of image size/scale. Pyramid pooling is also robust to object deformations. With these advantages, SPP-net should in general improve all CNN-based image classification methods. On the ImageNet 2012 dataset, we demonstrate that SPP-net boosts the accuracy of a variety of CNN architectures despite their different designs. On the Pascal VOC 2007 and Caltech101 datasets, SPP-net achieves state-of-the-art classification results using a single full-image representation and no fine-tuning. The power of SPP-net is also significant in object detection. Using SPP-net, we compute the feature maps from the entire image only once, and then pool features in arbitrary regions (sub-images) to generate fixed-length representations for training the detectors. This method avoids repeatedly computing the convolutional features. In processing test images, our method is 24-102x faster than the R-CNN method, while achieving better or comparable accuracy on Pascal VOC 2007. In ImageNet Large Scale Visual Recognition Challenge (ILSVRC) 2014, our methods rank #2 in object detection and #3 in image classification among all 38 teams. This manuscript also introduces the improvement made for this competition.Comment: This manuscript is the accepted version for IEEE Transactions on Pattern Analysis and Machine Intelligence (TPAMI) 2015. See Changelo

Diet of oceanic loggerhead sea turtles (Caretta caretta) in the central North Pacific

Diet analysis of 52 loggerhead sea turtles (Caretta caretta) collected as bycatch from 1990 to 1992 in the high-seas driftnet fishery operating between lat. 29.5°N and 43°N and between long. 150°E and 154°W demonstrated that these turtles fed predominately at the surface; few deeper water prey items were present in their stomachs. The turtles ranged in size from 13.5 to 74.0 cm curved carapace length. Whole turtles (n =10) and excised stomachs (n= 42) were frozen and transported to a laboratory for analysis of major faunal components. Neustonic species accounted for four of the five most common prey taxa. The most common prey items were Janthina spp. (Gastropoda); Carinaria cithara Benson 1835 (Heteropoda); a chondrophore, Velella velella (Hydrodia); Lepas spp. (Cirripedia), Planes spp. (Decapoda: Grapsidae), and pyrosomas (Pyrosoma spp.)

Shaping plasmon beams via the controlled illumination of finite-size plasmonic crystals

Plasmonic crystals provide many passive and active optical functionalities, including enhanced sensing, optical nonlinearities, light extraction from LEDs and coupling to and from subwavelength waveguides. Here we study, both experimentally and numerically, the coherent control of SPP beam excitation in finite size plasmonic crystals under focussed illumination. The correct combination of the illuminating spot size, its position relative to the plasmonic crystal, wavelength and polarisation enables the efficient shaping and directionality of SPP beam launching. We show that under strongly focussed illumination, the illuminated part of the crystal acts as an antenna, launching surface plasmon waves which are subsequently filtered by the surrounding periodic lattice. Changing the illumination conditions provides rich opportunities to engineer the SPP emission pattern. This offers an alternative technique to actively modulate and control plasmonic signals, either via micro- and nano-electromechanical switches or with electro- and all-optical beam steering which have direct implications for the development of new integrated nanophotonic devices, such as plasmonic couplers and switches and on-chip signal demultiplexing. This approach can be generalised to all kinds of surface waves, either for the coupling and discrimination of light in planar dielectric waveguides or the generation and control of non-diffractive SPP beams

Southern California marine sport fishing from privately-owned boats: catch and effort for July-September 1981

The catch landed and effort expended by private-boat sport fishermen were studied in southern California between July and September 1981, in order to determine the impact of one segment of the sport fishery on local marine resources. Fishermen returning from fishing trips were interviewed at launch ramps, hoists, and boat-rental facilities. This report contains quantitative data and statistical estimates of total effort, total catch, catch of preferred species, and length frequencies for those species whose catches are regulated by minimum size limits. An estimated 356,000 organisms were landed by 134,000 anglers and 5,400 divers. The major components of the catch were Pacific mackerel, Scomber japonicus, 89,000 landed; Pacific bonito, Sarda chiliensis, 82,000 landed; white croaker, Genyonemus lineatus, 34,000 landed; and bass, Paralabrax spp., 33,000 landed. These species made up two-thirds of the total catch. Anglers' compliance with size-limit regulations was variable. Approximately 88% of all measured bass were legal size. The proportion of legal-size white seabass, Atractoscion nobilis, rose from 9% last quarter to 18% this quarter, but dropped for California halibut, Paralichthys californicus, from 79% to 66%. Divers' compliance with size limits on abalone, Haliotis spp., rose slightly from 89% to 91%. (31pp.

Southern California marine sport fishing from privately-owned boats: Catch and effort for April-June 1981

The catch landed and effort expended by private-boat sport fishermen were studied in southern California between April and June 1981, in order to determine the impact of one segment of the sport fishery on local marine resources. Fishermen returning from fishing trips were interviewed at launch ramps, hoists, and boat-rental facilities. This report contains quantitative data and statistical estimates of total effort, total catch, catch of preferred species, and length frequencies for those species whose catches are regulated by minimum size limits. An estimated 310,000 organisms were landed by 106,000 anglers and 4,000 divers (more than twice the catch and effort estimated for the previous 3-month period). The major components of the catch were Pacific mackerel, Scomber japonicus, 63,000 landed; bass, Paralabrax spp., 61,000 landed; white croaker, Genyonemus lineatus, 52,000 landed, and Pacific bonito, Sarda chiliensis, 35,000 landed. These species contributed 70% of the total catch. Anglers' compliance with size limit regulations was variable. Approximately 89% of all measured bass were legal size. The proportion of legal size California halibut, Paralichthys californicus, rose from 60% last quarter to 79% this quarter. However, the percent of legal size California barracuda, Sphyraena argentea, was very low, 58%. Divers' compliance with minimum size limits dropped slightly: abalone, Haliotis spp., averaged 89% legal. (Document has 31 pages

Milk fatty acid composition and associated rumen lipolysis and fatty acid hydrogenation when feeding forages from intensively managed or semi-natural grasslands

In order to evaluate the effect of replacing intensive forage by semi-natural grassland products on rumen lipid metabolism and milk fatty acid composition, four lactating and rumen canulated Holstein cows were used in a 4×4 Latin square design. Four different diets were fed: diet 100 IM - 100% intensively managed silage (IM), diet 20 SPP - 80% IM plus 20% semi-natural but species poor silage (SPP), diet 60 SPP - 40% IM plus 60% SPP and diet 60 SPR - 40% IM plus 60% semi-natural species rich silage (SPR). The silages showed significant differences in total fat content and in proportions of C18:2 n-6 and C18:3 n-3. Despite the reduced dietary supply of C18:3 n-3 with diets 60 SPP and 60 SPR, differences in milk C18:3 n-3 were small, suggesting higher recoveries of C18:3 n-3. Presumably, the latter are related to a higher transfer efficiency of C18:3 n-3 from the duodenum to the mammary gland, since rumen biohydrogenation, estimated from rumen pool size and first order rumen clearance kinetics, were similar among diets. CLA c9t11 in milk from cows fed diet 60 SPR were almost doubled compared to feeding one of the other diets. This has been related to the partial inhibition of rumen biohydrogenation of C18:3 n-3 and/or C18:2 n-6, as suggested by the increased proportions of hydrogenation isomers and reduced stearic acid proportions in rumen pool samples. In conclusion, the results suggest that the use of semi-natural grasslands in the diet of the animals reduce to some extent complete rumen biohydrogenation, which leads to an increase in milk CLA