The electromagnetics of light transmission through subwavelength slits in metallic films

By numerically calculating the relevant electromagnetic fields and charge current densities, we show how local charges and currents near subwavelength structures govern light transmission through subwavelength apertures in a real metal film. The illumination of a single aperture generates surface waves; and in the case of slits, generates them with high efficiency and with a phase close to - pi with respect to a reference standing wave established at the metal film front facet. This phase shift is due to the direction of induced charge currents running within the slit walls. The surface waves on the entrance facet interfere with the standing wave. This interference controls the profile of the transmission through slit pairs as a function of their separation. We compare the calculated transmission profile for a two-slit array to simple interference models and measurements [Phys. Rev. B 77(11), 115411 (2008)]. (C) 2011 Optical Society of America

Surface Plasmon-Induced Band Gap in the Photocurrent Response of Organic Solar Cells

A 260 nm layer of organic bulk heterojunction blend of the polymer poly(3-hexylthiophene) (P3HT) and the fullerene [6,6]-phenyl C(61)-butyric (PCBM) was spin-coated in between aluminum and gold electrodes, respectively, on top of a laser inscribed azo polymer surface-relief diffraction grating. Angle-dependent surface plasmons (SPs) with a large band gap were observed in the normalized photocurrent by the P3HT-PCBM layer as a function of wavelength. The SP-induced photocurrents were also investigated as a function of the grating depth and spacing.

Quantitative determination of optical transmission through subwavelength slit arrays in Ag films: Role of surface wave interference and local coupling between adjacent slits

Measurement of the transmitted intensity from a coherent monomode light source through a series of subwavelength slit arrays in Ag films, with varying array pitch and number of slits, demonstrates enhancement (suppression) by factors of as much as 6 (9) when normalized to the transmission efficiency of an isolated slit. Pronounced minima in the transmitted intensity are observed at array pitches corresponding to lambda(SPP), 2 lambda(SPP), and 3 lambda(SPP), where lambda(SPP) is the wavelength of the surface plasmon polariton (SPP). The position of these minima arises from destructive interference between incident propagating waves and pi-phase-shifted SPP waves. Increasing the number of slits to four or more does not increase appreciably the per-slit transmission intensity. A simple interference model fits well the measured transmitted intensity profile.

Coordination dynamics and attentional costs of continuous and discontinuous bimanual circle drawing movements

It has been suggested that the temporal control of rhythmic unimianual movements is different between tasks requiring continuous (e.g., circle drawing) and discontinuous movements (e.g., finger tapping). Specifically, for continuous movements temporal regularities are ail emergent property, whereas for tasks that involve discontinuities timing is ail explicit part of the action goal. The present experiment further investigated the control of continuous and discontinuous movements by comparing the coordination dynamics and attentional demands of bimanual continuous circle drawing with bimanual intermittent circle drawing. The intermittent task required participants to insert a 400 ms pause between each cycle while circling. Using dual-task methodology, 15 right-handed participants performed the two circle drawing tasks, while vocally responding to randomly presented auditory probes. The circle drawing tasks were performed in symmetrical and asymmetrical coordination modes and at movement frequencies of 1 Hz and 1.7 Hz. Intermittent circle drawing exhibited superior spatial and temporal accuracy and stability than continuous circle drawing supporting the hypothesis that the two tasks have different underlying control processes. In terms of attentional cost, probe RT was significantly slower during the intermittent circle drawing task than the continuous circle drawing task across both coordination modes and movement frequencies. Of interest was the finding that in the intermittent circling task reaction time (RT) to probes presented during the pause between cycles did not differ from the RT to probes occurring during the circling movement. The differences in attentional demands between the intermittent and continuous circle drawing tasks may reflect the operation of explicit event timing and implicit emergent timing processes, respectively. (C) 2008 Elsevier B.V. All rights reserved.

The four-element Chua`s circuit

A new circuit configuration, linearly conjugate to the standard Chua`s circuit, is presented. Its distinctive feature is that the equations now admit an additional parameter, which controls the dissipation in the network connected to the Chua diode. In the limiting case we obtain the simplest chaotic circuit, consisting of a piecewise-linear resistor and three lossless elements.

Bidimensional codes recorded on an oxide glass surface using a continuous wave CO(2) laser

Surface heat treatment in glasses and ceramics, using CO(2) lasers, has attracted the attention of several researchers around the world due to its impact in technological applications, such as lab-on-a-chip devices, diffraction gratings and microlenses. Microlens fabrication on a glass surface has been studied mainly due to its importance in optical devices (fiber coupling, CCD signal enhancement, etc). The goal of this work is to present a systematic study of the conditions for microlens fabrications, along with the viability of using microlens arrays, recorded on the glass surface, as bidimensional codes for product identification. This would allow the production of codes without any residues (like the fine powder generated by laser ablation) and resistance to an aggressive environment, such as sterilization processes. The microlens arrays were fabricated using a continuous wave CO(2) laser, focused on the surface of flat commercial soda-lime silicate glass substrates. The fabrication conditions were studied based on laser power, heating time and microlens profiles. A He-Ne laser was used as a light source in a qualitative experiment to test the viability of using the microlenses as bidimensional codes.

Gas flow analysis in a Kraft recovery boiler

Demands for optimal boiler performance and increased concerns in lowering emission have always been the driving force in the reevaluation and evolution of the Kraft boiler: specifically the air distribution strategies that are directly related to achieving increased residence time of flue gas combustion inside the furnace which in turn lowers atmosphere emission levels and enhances boiler operation. This paper presents the results of a study that analyzes the interaction of the different multilevel air injections have on flue gas flow patterns including various quaternary air supply arrangements. Additionally, this study assesses the performance of the CFD (Computational Fluid Dynamics) model against data available in literature. Simulations were performed considering isothermal and incompressible flows, and did not take into account thermal phenomena or chemical reactions. The numerical solutions generated proved to be coherently related to the data available in literature, and provided proof of the efficiency of tertiary level air injection, as well as revealed that quaternary air injection ports arranged in a symmetrical configuration is most suitable for optimal equipment operation. (C) 2010 Elsevier B.V. All rights reserved.

Denisiuk-type reflection holography display with sillenite crystals for imaging and interferometry of small objects

A novel setup for imaging and interferometry through reflection holography with Bi12TiPO20(BTO) sillenite photorefractive crystals is proposed. A variation of the lensless Denisiuk arrangement was developed resulting in a compact, robust and simple interferometer. A red He-Ne laser was used as light source and the holographic recording occurred by diffusion with the grating vector parallel to the crystal [0 0 1]-axis. In order to enhance the holographic image quality and reduce noise a polarizing beam splitter (PBS) was positioned at the BTO input and the crystal was tilted around the [0 0 1]-axis. This enabled the orthogonally polarized transmission and diffracted beams to be separated by the PBS, providing the holographic image only. The possibility of performing deformation and strain analysis as well as vibration measurement of small objects was demonstrated. (C) 2007 Elsevier B.V. All rights reserved.

Factors associated with pelvic asymmetry in transverse plane during gait in patients with cerebral palsy

The purpose of this study was to describe the patterns of pelvic rotational asymmetry in the transverse plane and identify the possible factors related to this problem. One thousand and forty-five patients with cerebral palsy (CP) and complete documentation in the gait laboratory were reviewed in a retrospective study. Pelvic asymmetry in the transverse plane was observed in 52.7% of the patients; and to identify the possible causes of pelvic retraction, clinical (Thomas test, popliteal angle, and gastrocnemius tightness) and dynamic parameters (mean rotation of the hip in stance, minimum hip flexion, minimum knee flexion, and peak ankle dorsiflexion) were evaluated. The association between these parameters and pelvic retraction was assessed statistically. The results showed that 75.7% of patients with asymmetric pattern of the pelvis had clinical diagnosis of diplegic spastic CP. Among the patients with asymmetrical CP, the most common pattern was pelvic retraction on the affected side. The relationship between pelvic retraction and internal hip rotation was stronger in patients with asymmetrical diplegic CP than in those with hemiplegic (P<0.001) or symmetrical diplegic CP (P=0.014). All of the patients exhibited a significant association among clinical parameters (Thomas test, popliteal angle, and gastrocnemius tightness) and pelvic retraction. In conclusion, pelvic retraction seems to be a multifactorial problem, and the etiology can change according to topographic classification, which must be taken into account during the decision-making process in patients with CP. J Pediatr Orthop B 18:320-324 (C) 2009 Wolters Kluwer Health vertical bar Lippincott Williams & Wilkins.

Ultrasound Propagation Velocity and Broadband Attenuation Can Help Evaluate the Healing Process of an Experimental Fracture

Ultrasonometry seems to have a future for the evaluation of fracture healing. Ultrasound propagation velocity (USPV) significantly decreases at the same time that bone diameter decreases as healing takes place, thus approaching normal values. In this investigation, both USPV and broadband ultrasound attenuation (BUA) were measured using a model of a transverse mid-diaphyseal osteotomy of sheep tibiae. Twenty-one sheep were operated and divided into three groups of seven, according to the follow-up period of 30, 60, and 90 days, respectively. The progress of healing of the osteotomy was checked with monthly conventional radiographs. The animals were killed at the end of the period of observation of each group, both operated-upon and intact tibiae being resected and submitted to the measurement of underwater transverse and direct contact transverse and longitudinal USPV and BUA at the osteotomy site. The intact left tibia of the 21 animals was used for control, being examined on a symmetrical diaphyseal segment. USPV increased while BUA decreased with the progression of healing, with significant differences between the operated and untouched tibiae and between the periods of observation, for most of the comparisons. There was a strong negative correlation between USPV and BUA. Both USPV and BUA directly reflect and can help predict the healing of fractures, but USPV alone can be used as a fundamental parameter. Ultrasonometry may be of use in clinical application to humans provided adequate adaptations can be developed. (C) 2010 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 29:444-451, 2011

Leigh-like syndrome with the T8993G mutation in the mitochondrial ATPase 6 gene: long-term follow-up discloses a slowly progressive course

We describe the long-term clinical outcome of a patient with Leigh-like syndrome presenting as an early onset encephalopathy and peripheral neuropathy caused by the T8993G mutation in the mitochondrial DNA (mtDNA). Clinical follow-up for 20 years revealed a peculiar pattern of slow disease progression, characterized by the addition of new minor deficits, while worsening of previous symptoms was mild. Brain MRI revealed cerebellar atrophy, diffuse demyelination of corona radiata and parietal white matter, and bilateral and symmetrical putaminal lesions. The proportion of mutant mtDNAs in blood was 72% (+/- 0.02%) and in skeletal muscle was 81% (+/- 0.4%). Leigh-like syndrome caused by the T8993G mtDNA mutation is a progressive disease, although not necessarily associated with an aggressive clinical course. (C) 2009 Elsevier B.V. All rights reserved.

Analysis of the gutta-percha filled area in C-shaped mandibular molars obturated with a modified MicroSeal technique

To analyse the gutta-percha filled area of C-shaped molar teeth root filled with the modified MicroSeal technique with reference to the radiographic features and the C-shaped canal configuration. Twenty-three mandibular second molar teeth with C-shaped roots were classified according to their radiographic features as: type I - merging, type II - symmetrical and type III - asymmetrical. The canals were root filled using a modified technique of the MicroSeal system. Horizontal sections at intervals of 600 mu m were made 1 mm from the apex to the subpulpal floor level. The percentage of gutta-percha area from the apical, middle and coronal levels of the radiographic types was analysed using the Kruskal-Wallis test. Complementary analysis of the C-shaped canal configurations (C1, C2 and C3) determined from cross-sections from the apical third was performed in a similar way. No significant differences were found between the radiographic types in terms of the percentage of gutta-percha area at any level (P > 0.05): apical third, type I: 77.04%, II: 70.48% and III: 77.13%, middle third, type I: 95.72%, II: 93.17%, III: 91.13% and coronal level, type I: 98.30%, II: 98.25%, III: 97.14%. Overall, the percentage of the filling material was lower in the apical third (P < 0.05). No significant differences were found between the C-shaped canal configurations apically; C1: 72.64%, C2: 79.62%, C3: 73.51% (P > 0.05). The percentage of area filled with gutta-percha was similar in the three radiographic types and canal configuration categories of C-shaped molars. These results show the difficulty of achieving predictable filling of the root canal system when this anatomical variation exists. In general, the apical third was less completely filled.

Effect of substrate on the locomotion behaviour of the South American iguanian lizard Polychrus acutirostris

Arboreal and terrestrial habitats impose different constraints on tetrapod locomotion. We studied Polychrus acutirostris, a tree-dwelling lizard that also moves on the ground, in order to evaluate the effects of support incline and diameter on locomotion parameters. Limb movements of six specimens were filmed to quantify kinematic variables (velocity, stride frequency, stride length, and limb coordination) on distinct perch diameters (4.0, 1.5, 0.8 cm) and inclines (90, 45, and on level ground). The results show a notable slowness in arboreal habitat combined with a relatively fast locomotion when using the ground as temporary habitat. These animals developed walking trots mainly using lateral sequence. Non-symmetrical trots adopted at the highest velocities on the ground indicate difficulties of ""accommodation"" to the constraints imposed by this condition. Velocity generally decreases with the decreasing diameter, and with increasing incline, of the supports. Slowness, gaits favouring the body stability, elective role of the stride frequency in the modulation of the speed, and the role of the hindlimb in the force exchange to propel the body, constitute the main features of the locomotion pattern of P. acutirostris.

Systemic Inflammatory Reaction After Silicone Breast Implant

Systemic inflammation after augmentation mammaplasty with modern silicone implants is not currently recognized. In a prospective controlled study, C-reactive protein and other variables were monitored, aiming to test this hypothesis in a young cohort of patients. Females (18-30 years old, BMI = 18.5-30 kg/m(2), N = 52) were consecutively recruited for breast implant (n = 24, Group I) and for abdominal liposuction (n = 28, Group II/Controls). Patients were interviewed at baseline and followed until 6 months after operation. Variables included demographic and clinical information, surgical outcome, inflammatory markers and autoantibodies. Operations were well tolerated, without surgical or infectious complications. Mean prosthesis size was 258 +/- A 21 ml (range = 220-280) and mean aspirate of liposuction was 1972 +/- A 499 ml (range = 1200-3000). Preoperative, 2-month, and 6-month C-reactive protein concentrations for breast implant patients were 1.3 +/- A 1.2, 4.8 +/- A 3.0, and 4.3 +/- A 6.4 mg/l and for liposuction 3.5 +/- A 2.7, 3.5 +/- A 2.1, and 2.2 +/- A 2.2 mg/l, respectively. Change at 2 months was significant (p = 0.001). Autoantibody investigation failed to reveal remarkable aberrations, except for anticardiolipin elevation, which was nearly symmetrical in the two groups. C-reactive protein levels increased after operation and correlated with proinflammatory and procoagulatory indices. A mild increase in anticardiolipin IgM occurred but differences between populations were lacking. Despite excellent cosmetic outcomes and lack of complications, acute phase reaction could signal ongoing immunogenicity of silicone and long-term monitoring is recommended.

Hyaluronidase increases the duration of mepivacaine in inferior alveolar nerve blocks

Purpose: To evaluate the duration of the effect of mepivacaine when hyaluronidase is injected immediately prior to the end of pulpal anesthesia. Patients and Methods: Forty bilateral, symmetrical third molar surgeries were performed in 20 healthy patients. Inferior alveolar nerve block was induced using 2.8 mL 2% mepivacaine with epinephrine. Hyaluronidase (75 turbidity-reducing units) or a placebo was injected 40 minutes after the beginning of pulpar anesthesia (randomized and double-blind trial). The duration of effect in the pulpal and gingival tissues was evaluated by response to painful electrical stimuli applied to the Adjacent premolar, and by mechanical stimuli (pin prick) to the vestibular gingiva, respectively. Results: in both tissues, the duration of anesthetic effect with hyaluronidase was longer (P <.01) than with the placebo. Conclusion: Hyaluronidase increases the duration of mepivacaine in inferior alveolar nerve blocks. (c) 2008 American Association of Oral and Maxillofacial Surgeons.