Mid-IR plasmonics: near-field imaging of coherent plasmon modes of silver nanowires.

Chemically synthesized metallic nanostructures can exhibit a strong local optical field enhancement associated with their high degree of crystallinity and well-defined geometry-dependent surface plasmon resonances. The extension of the plasmon modes into the mid-IR spectral range (3-30 microm) is shown for micrometer-sized nanowires with high aspect ratios available in the form of pentagonally twinned Ag crystallites as grown by polyol synthesis. Using scattering-scanning near-field optical microscopy, the associated IR plasmon modes are identified, and their underlying spatial distribution and enhancement of the optical polarization density is measured via phase, amplitude, and polarization resolved optical vector-field mapping. The transition from dipolar to multipolar resonances is observed and described by modeling the Ag wires using a modified cylindrical waveguide theory. For 10.6 microm excitation, dipole antenna resonances are observed at a resonant length of L = lambda(eff)/2 with lambda(eff) approximately 10.6 microm/(1.8 +/- 0.5) approximately 6 +/- 2 microm. This effective wavelength scaling is the result of electronic damping, despite the high aspect ratios of the wires of order 1:10 to 1:200. With the optical cycle period tau(IR) being comparable to the Drude relaxation time of tau approximately 40 fs the mid-IR defines the low-energy limit of the coherent plasmon regime (tau(IR) less, similar tau) at the transition to purely geometric antenna resonances (tau(IR) > tau).

Squamous cell carcinoma with necrotizing scleritis.

PURPOSE: To report on a case of limbal squamous cell carcinoma (SCC) with necrotizing scleritis in a young, previously healthy, white Australian male. METHODS: A 31-year-old man presented with a left limbal lesion intermittently causing a red eye and foreign body sensation. He had enjoyed surfing for many years. Repeat HIV tests were negative and the lesion was biopsied. RESULTS: Biopsy showed a well-differentiated SCC apparently arising in an intra-epithelial (in situ) carcinoma of the conjunctiva. The lesion was excised and a corneoscleral graft repair was performed. CONCLUSION: The present case highlights the potential for a significant increase in the prevalence of ocular surface neoplasia in healthy young people who have had excessive UV-B exposure.

Applying modular classifiers to mammographic mass classification.

Classification is the last step in the computer aided diagnosis (CAD) system for determining whether a breast mass segmented from a digital mammogram is malignant or benign. Hence it is important to improve sensitivity at this stage. This work investigates the use of modular classifier (MoC) schemes, namely bagging and adaboost algorithms, for automated classification of mammographic masses. CAD systems containing a MoC are compared to CAD systems that contain traditional classifiers (TrC), for example single nearest mean or maximum likelihood classifiers. This study included 200 digitized mammograms, each manually segmented by a radiologist. In order to test the MoC and TrC approaches, conventional shape based features were extracted from the segmented masses. These features were then optimized using Fischer's linear discriminant analysis (LDA). When no LDA was utilized, it was observed that MoC schemes increased the sensitivity from 74% to 83% over the TrC approaches. After performing LDA, the sensitivity increased from 83% to 88% for TrC and MoC schemes, respectively.

Strabismus in infants of opiate-dependent mothers.

AIM: At a follow-up clinic for infants of opiate-dependent mothers it was noted that more infants than expected developed strabismus. This study aimed to assess the prevalence of strabismus and the need for active strabismus surveillance in this population. METHODS: Consecutive infants of opiate-dependent mothers born over an 18 mo period were recalled for ophthalmological assessment by an ophthalmologist and orthoptist. Those unable to attend were surveyed by telephone using a questionnaire. RESULTS: 49 (69%) of the 71 eligible infants were recalled at a mean age of 21 mo (range 6-39); 29 had a full ophthalmological examination and the remaining 20 completed the questionnaire only. Seven (14%) of the 49 recalled infants had strabismus on examination; 4 needed glasses or patching. A further seven (14%) had a history of intermittent strabismus but declined formal examination. Another child had significant hypermetropia without strabismus. The mean age at which strabismus was observed was 8.3 mo (range birth to 19 mo). The presence of strabismus was not significantly influenced by conditions at birth, maternal drug doses, family history or need for or duration of abstinence treatment. CONCLUSION: The rate of strabismus in infants of opiate-dependent mothers was at least 10 times that in the general population. As attendance at follow-up is often poor, paediatricians should be aware of the association to encourage opportunistic assessment and ophthalmological surveillance of this population.

Lactate and pyruvate levels in the testicular vein of subfertile males with varicocele as a test for the theory of underlying hypoxia.

To test for the theory of testicular hypoxia in subfertile males with varicocele, the testicular mean blood level of lactate and pyruvate was compared with that of a control group. Statistical analysis of data showed a lower mean of lactate and of pyruvate in the testicular vein of varicocele patients. It is concluded that in varicocele there is no accumulation of lactic acid, thus excluding testicular hypoxia. Since lactate and pyruvate mean concentrations in testicular vein were correlated, it is suggested that in cases of varicocele there is defective glycolysis preceding the stage of pyruvate formation.