Fabrication of plasmonic structures with well-controlled nanometric features: a comparison between lift-off and ion beam etching.

After providing a detailed overview of nanofabrication techniques for plasmonics, we discuss in detail two different approaches for the fabrication of metallic nanostructures based on e-beam lithography. The first approach relies on a negative e-beam resist, followed by ion beam milling, while the second uses a positive e-beam resist and lift-off. Overall, ion beam etching provides smaller and more regular features including tiny gaps between sub-parts, that can be controlled down to about 10 nm. In the lift-off process, the metal atoms are deposited within the resist mask and can diffuse on the substrate, giving rise to the formation of nanoclusters that render the nanostructure outline slightly fuzzy. Scattering cross sections computed for both approaches highlight some spectral differences, which are especially visible for structures that support complex resonances, such as Fano resonances. Both techniques can produce useful nanostructures and the results reported therein should guide the researcher to choose the best suited approach for a given application, depending on the available technology.

Near-field optical images of subwavelength annular aperture arrays exhibiting an extraordinary transmission.

In this paper, we present near-field optical images of nanostructures exhibiting an extraordinary transmission. These structures consist of annular aperture arrays engraved in a metallic film: they are quite promising structures for nanophotonics because of their high transmission directly linked to a guided mode mediated by each annular aperture. We first briefly explain our fabrication process (focused ion beam milling), then we expose the experimental setup of the near-field optical microscope working both in reflection and transmission modes. For the reflection mode, the 'coffee-bean' structure of the electromagnetic field predicted by the theory has been quite well reproduced. For the transmission mode, we present preliminary experimental results concerning the influence of the wavelength and the polarization of the incident beam on the obtained near-field images.

Cortical mapping of right hemisphere functions.

Right hemisphere functions were examined during cortical stimulation in six patients undergoing epilepsy surgery. Two patients showed mild hemispatial neglect and constructional disability with stimulation of several sites in the inferior parietal lobule and posterior temporal lobe. Two other patients showed no disruption of visuospatial functions with stimulation of similar parietal or posterior temporal sites. Nonverbal acoustic perception of environmental sounds was not disrupted with stimulation of right superior temporal cortex in one patient, and musical abilities were not affected by right superior temporal stimulation in another patient. Nondominant hemisphere functions may be more widely distributed and less localized than linguistic functions in the dominant hemisphere.

Emotional versus nonemotional lexical perception in patients with right and left brain damage.

OBJECTIVE: This study examined lexical emotional perception in patients with unilateral brain damage. BACKGROUND: Hypotheses pertaining to laterality and emotion were tested. More specifically, we were interested in whether the right hemisphere is dominant for verbally-presented emotion. In addition, we examined whether emotional content improves the performance of patients with left brain damage (LBD) and language deficits. METHOD: Subjects were 11 patients with right brain damage (RBD), 10 patients with LBD, and 15 normal control adults. The subject groups did not differ significantly on demographic or basic cognitive variables; the patient groups were similar on neurologic variables. Parallel emotional experimental and nonemotional control tasks included word identification (or recognition), sentence identification, and word discrimination. There were eight emotional categories (e.g., happiness) and eight nonemotional categories (e.g., vision). RESULTS: A significant interaction among Group, Condition, and Task revealed that patients with RBD were significantly impaired relative to patients with LBD and normals within the emotional condition, particularly for the identification tasks. Furthermore, the performance of patients with LBD and language deficits was improved by emotional content for the sentence identification task. CONCLUSIONS: These findings suggest that the right hemisphere has a unique contribution in the identification of lexical emotional stimuli. Implications for rehabilitation of patients with LBD and language deficits and patients with RBD by means of emotion-based strategies are discussed.

Facial asymmetry during emotional expression: gender, valence, and measurement technique.

The purpose of the current study was to examine 49 extant experiments of facial asymmetry during emotional expression in normal adult males and females in regard to gender, valence, and measurement technique. When facial asymmetry was evaluated by trained judges or muscle quantification, facial expressions were left-sided, a finding implicating the right cerebral hemisphere in emotional expression. However, when self-report experiential methods were utilized, the valence hypothesis received some support. Although there was some indication in single-gender studies of greater facial lateralization for males than for females, studies involving both males and females yielded no systematic asymmetry patterns as a function of gender.

Right hemisphere emotional perception: evidence across multiple channels.

Emotional perception was examined in stroke patients across 3 communication channels: facial, prosodic, and lexical. Hemispheric specialization for emotion was tested via right-hemisphere (RH) and valence hypotheses, and relationships among channels were determined. Participants were 11 right-brain-damaged (RBD), 10 left-brain-damaged (LBD), and 15 demographically matched normal control (NC) adults. Experimental measures, with analogous psychometric properties, were identification and discrimination tasks, including a range of positive and negative emotions. Nonemotional control tasks were used for each channel. For identification, RBDs were significantly impaired relative to LBDs and NCs across channels and valences, supporting the RH hypothesis. No group differences emerged for discrimination. Findings were not influenced by demographic, clinical, or control variables. Correlations among the channels were more prominent for normal than for brain-damaged groups.

Predesquamin inhibits desquamation.

Predesquamin is a Con A binding glycoprotein from human epidermis, with a molecular weight of 650 kDa. Its isolation and characterization are detailed, as well as the preparation of a polyclonal antibody to it. The antibody labels primarily the lower stratum corneum in fluorescent and ultrastructural immunolocalization, both in normal skin and plantar callus. A desquamation model system, in which plantar callus is incubated with the chelating agent ethylenediaminetetraacetic acid (EDTA) is refined by substituting for EDTA the Ca(2+)-specific ethylene glycol bis(beta-aminoethyl ether)-N,N'-tetraacetic acid. Moreover, the shedding activity can be suppressed by raising the Ca2+ concentration. Within this model, it is demonstrated that predesquamin at nanomolar concentrations inhibits squame shedding in a dose-dependent manner. We conclude that predesquamin plays an important role in blocking premature desquamation of the lower stratum corneum.

Culture of basal cell carcinoma.

Studies of basal cell carcinoma have been hindered by a lack of a suitable and reproducible tissue-culture model system. We have succeeded in growing this tumor in primary culture from eight different patients. We can separate and grow the tumor cells and the stromal cell component. We also culture normal keratinocytes and fibroblasts from the same patient for comparative studies. All the cell types have been subcultured four to five times and cryopreserved. The normal keratinocytes were indistinguishable from the tumor cells in ploidy, in rate of growth, and in the failure to express ICAM-1. Both cell types also fail to synthesize the matrix proteins: types I and IV collagens. Differences were noted in the expression of fibronectin and the bullous pemphigoid antigen, with the normal cells expressing the antigens although the tumor cells did not. Interferons exogenously added to the culture media preferentially killed the basal cell carcinoma cells, as compared to normal keratinocytes from the same patients. We believe that our culture system opens possibilities for biochemical and molecular studies of this disease, and for in vitro testing of antitumor agents for clinical therapy.