Nonequilibrium plasmon emission drives ultrafast carrier relaxation dynamics in photoexcited graphene

The fast decay of carrier inversion in photoexcited graphene has been attributed to optical phonon emission and Auger recombination. Plasmon emission provides another pathway that, as we show here, drives the carrier relaxation dynamics on ultrafast time scales. In studying the nonequilibrium relaxation dynamics we find that plasmon emission effectively converts inversion into hot carriers, whose energy is then extracted by optical phonon emission. This mechanism not only explains the observed femtosecond lifetime of inversion but also offers the prospect for atomically thin ultrafast plasmon emittersThis work has been funded by the Engineering and Physical Sciences Research Council (United Kingdom), the Leverhulme Trust (United Kingdom), the European Research Council (ERC- 2011-AdG Proposal No. 290981) and the Spanish MINECO (Grant No. MAT2011-28581-C02-01

Effect of Glass Fiber Surface Treatments on Mechanical Strength of Epoxy Based Composite Materials

Sizing glass fibers with silane coupling agents enhances the adhesion and the durability of the fiber/polymer matrix interface in composite materials. There are several tests to determine the interfacial strength between a fiber and resin, but all of them present difficulties in interpreting the results and/or sample preparation. In this study, we observed the influence of different aminosilanes fiber coatings on the resistance of epoxy-based composite materials using a very easy fractographic test. In addition, we tried a new fluorescence method to get information on a molecular level precisely at the interface. Strength was taken into account from two standpoints: (i) mechanical strength and (ii) the resistance to hydrolysis of the interface in oriented glass-reinforced epoxy-based composites. Three silanes: gamma-aminopropyltriethoxysilane, gamma-Aminopropylmethyldiethoxysilane, and gamma-Aminopropyldimethylethoxysilane were used to obtain different molecular structures at the interface. It was concluded that: (i) the more accessible amine groups are, the higher the interface rigidity is; (ii) an interpenetrating network mechanism seems to be the most important for adhesion and therefore to the interfacial strength; and (iii) the higher the degree of crosslinking in the silane coupling layer is, the higher the hydrolytic damage rate is.The authors thank the Comunidad Auto´noma de Madrid (CAM: the Madrid regional government) for funding through Project (07N/0002/98)

Gain-assisted extraordinary optical transmission through periodic arrays of subwavelength apertures

We theoretically investigate the amplification of extraordinary optical transmission (EOT) phenomena in periodic arrays of subwavelength apertures incorporating gain media. In particular, we consider a realistic structure consisting of an opaque silver film perforated by a periodic array of slits and clad on each side by an optically pumped dielectric thin film containing rhodamine dye molecules. By solving the semiclassical electronic rate equations coupled to rigorous finite-element simulations of the electromagnetic fields, we show how the resonant electric-field enhancement associated with EOT properties enables complete ohmic loss compensation at moderate pump intensity levels. Furthermore, our calculations show that, as a consequence of the strong spatial hole-burning effects displayed by the considered structures, three separate regimes of operation arise: the system can behave as an absorber, an optical amplifier or a laser, depending on the value of the pump intensity. A discussion on the feasibility of reaching the lasing regime in the considered class of structures is also presentedThis work was sponsored by the Spanish Ministry of Science and Innovation under the projects MAT2009-06609-C02 and CSD2007-046-NanoLight and by the Ramón y Cajal program (grant no. RyC-2009-05489

Session D7: Fishway with Two Entrance Locations: Understanding its importance for Iberian Barbel

Abstract In recent years, in the Iberian Peninsula, many fish passes have been built and improved. To ensure the proper operation of these, it is essential to carry out an evaluation and subsequent monitoring, considering both biologic and hydraulic aspects. We analyze the performance of Iberian barbel –Luciobarbus bocagei (Steindachner, 1864)– in a technical fishway: pool and weir, with bottom orifice. It is located in the Josefina hydropower plant (Duero River, Valladolid, Spain). Fish ladder has two fish entrances: one in the turbine outlet channel and another in the natural river course. Both the most relevant hydraulic values (flow, velocity, volumetric energy dissipation) and biological parameters (movement pattern, attraction, entry and passage) were measured. Biological assessment was conducted in the spawning season using PIT tag technology. The main influence on upstream movement was river discharge. There were no preferences between path selection; and ascent success and transit time were similar between two entrances.. Results highlight the importance of two access points for improve entrance and decrease migration delay

The Functional Anatomy and Innervation of the Platysma is Segmental:Implications for Lower Lip Dysfunction, Recurrent Platysmal Bands, and Surgical Rejuvenation

BACKGROUND: Despite the central role of the platysma in face and neck rejuvenation, much confusion exists regarding its surgical anatomy.OBJECTIVES: This study was undertaken to clarify the regional anatomy of the platysma and its innervation pattern and to explain clinical phenomena, such as the origin of platysmal bands and their recurrence, and the etiology of lower lip dysfunction after neck lift procedures.METHODS: Fifty-five cadaver heads were studied (16 embalmed, 39 fresh, mean age 75 years). Following preliminary dissections and macro-sectioning, a series of standardized layered dissections were performed, complemented by histology and sheet plastination.RESULTS: In addition to its origin and insertion, the platysma is attached to the skin and deep fascia across its entire superficial and deep surfaces. This composite system explains the age-related formation of static platysmal bands, recurrent platysma bands after complete platysma transection, and recurrent anterior neck laxity after no-release lifting. The facial part of the platysma is primarily innervated by the marginal mandibular branch of the facial nerve, while the submandibular platysma is innervated by the "first" cervical branches which terminate at the mandibular origin of the depressor labii inferioris. This pattern has implications for post-operative dysfunction of the lower lip, including pseudo-paralysis, and potential targeted surgical denervation.CONCLUSIONS: This anatomical study, using layered dissections, large histology, and sheet-plastination, fully describes the anatomy of the platysma including its bony, fascial, and dermal attachments, as well as its segmental innervation including its nerve danger zones. It provides a sound anatomical basis for the further development of surgical techniques to rejuvenate the neck with prevention of recurrent platysmal banding.</p

The Functional Anatomy and Innervation of the Platysma is Segmental:Implications for Lower Lip Dysfunction, Recurrent Platysmal Bands, and Surgical Rejuvenation

BACKGROUND: Despite the central role of the platysma in face and neck rejuvenation, much confusion exists regarding its surgical anatomy.OBJECTIVES: This study was undertaken to clarify the regional anatomy of the platysma and its innervation pattern and to explain clinical phenomena, such as the origin of platysmal bands and their recurrence, and the etiology of lower lip dysfunction after neck lift procedures.METHODS: Fifty-five cadaver heads were studied (16 embalmed, 39 fresh, mean age 75 years). Following preliminary dissections and macro-sectioning, a series of standardized layered dissections were performed, complemented by histology and sheet plastination.RESULTS: In addition to its origin and insertion, the platysma is attached to the skin and deep fascia across its entire superficial and deep surfaces. This composite system explains the age-related formation of static platysmal bands, recurrent platysma bands after complete platysma transection, and recurrent anterior neck laxity after no-release lifting. The facial part of the platysma is primarily innervated by the marginal mandibular branch of the facial nerve, while the submandibular platysma is innervated by the "first" cervical branches which terminate at the mandibular origin of the depressor labii inferioris. This pattern has implications for post-operative dysfunction of the lower lip, including pseudo-paralysis, and potential targeted surgical denervation.CONCLUSIONS: This anatomical study, using layered dissections, large histology, and sheet-plastination, fully describes the anatomy of the platysma including its bony, fascial, and dermal attachments, as well as its segmental innervation including its nerve danger zones. It provides a sound anatomical basis for the further development of surgical techniques to rejuvenate the neck with prevention of recurrent platysmal banding.</p