Manipulating polarization of light with ultrathin epsilon-near-zero metamaterials.

One of the basic functionalities of photonic devices is the ability to manipulate the polarization state of light. Polarization components are usually implemented using the retardation effect in natural birefringent crystals and, thus, have a bulky design. Here, we have demonstrated the polarization manipulation of light by employing a thin subwavelength slab of metamaterial with an extremely anisotropic effective permittivity tensor. Polarization properties of light incident on the metamaterial in the regime of hyperbolic, epsilon-near-zero, and conventional elliptic dispersions were compared. We have shown that both reflection from and transmission through λ/20 thick slab of the metamaterial may provide nearly complete linear-to-circular polarization conversion or 90° linear polarization rotation, not achievable with natural materials. Using ellipsometric measurements, we experimentally studied the polarization conversion properties of the metamaterial slab made of the plasmonic nanorod arrays in different dispersion regimes. We have also suggested all-optical ultrafast control of reflected or transmitted light polarization by employing metal nonlinearities.

Towards nonlinear plasmonic devices based on metallic nanorods.

The nonlinear optical properties of gold nanorod arrays have been studied with a two-colour continuously working (CW) pump-probe spectroscopy. The hybridization of the nanorod arrays with a nonlinear polymer (poly-3BCMU) has been investigated for the purposes of active photonic component design. The sensitivity of the plasmonic resonances of the hybrid nanostructured system to pump-induced changes in the refractive index of the polymer surroundings has been used to control the optical extinction of the array. Both reversible and non-reversible behaviour has been observed reflecting the combined effects from the third-order nonlinear response of the hybrid metallo-dielectric system and post-photopolymerization triggered reactions in the polymer.

The relationships among pulmonary function, aerobic fitness, and cognitive functioning in older COPD patients.

STUDY OBJECTIVES: To study the predictive relationships among age, pulmonary function, aerobic fitness, and cognition in people with COPD. DESIGN: Observational study conducted during baseline testing with COPD patients who volunteered to participate in an exercise intervention. PARTICIPANTS: Older adults (age, 56 to 80 years) with COPD. MEASUREMENTS AND RESULTS: Age, depression, education level, aerobic fitness, blood oxygen saturation levels, and pulmonary function were assessed. Participants were randomly assigned to take cognitive tests of (1) fluid intelligence, (2) processing speed and working memory span, or (3) processing speed and inhibition. After controlling for education and depression (F(2,57) = 7.43; r(2) = 0. 21), performance on the 6-min walk (F(1,56) = 15.27; r(2) = 0.17) and age (F(1,55) = 7.52; r(2) = 0.08) were significant predictors of fluid intelligence. On the speed-of-processing task, performance on the 6-min walk (F(1,30) = 8.17; r(2) = 0.20), maximum voluntary ventilation (F(1,29) = 5.81; r(2) = 0.16), and age (F(1,28) = 5.26; r(2) = 0.10) were significant predictors. FVC was a significant predictor (F(1,25) = 6.37; r(2) = 0.18) of working memory span. The ability to inhibit a response was not significantly predicted by any of the variables assessed. CONCLUSIONS: In an older COPD sample, age, aerobic fitness, and pulmonary function are predictive of cognitive performance on various tasks. In particular, age and aerobic fitness are predictive of speed of processing, which is a cognitive variable that may itself underlie performance on a majority of cognitive tasks.

Latex allergy in the operating room: case report and a brief review of the literature.

A patient with a history of spina bifida and cerebral palsy was anesthetized for an ileal conduit. The procedure was uneventful until penetration of the abdominal cavity, immediately after which the patient suffered severe hypotension and her peak inspiratory pressure doubled. The patient's skin became flushed and the capnogram tracing was consistent with bronchospasm. The patient was treated with phenylephrine hydrochloride (Neo-Synephrine), and then epinephrine. This was followed with an epinephrine infusion, intravenous (i.v.) methylprednisolone sodium succinate (Solu-Medrol), inhaled albuterol sulfate, and diphenhydramine hydrochloride (Benadryl) i.v.. The patient responded to these interventions and the procedure was completed without further incident. A diagnosis of latex allergy was made based on the patient's clinical status, underlying diseases, and positive postoperative radioallergosorbent test (RAST). Anesthesiologists must be able to diagnose the signs and symptoms of allergic reactions in patients under anesthesia. This article will review the types of hypersensitivity reactions involved, define the risk groups, and examine the treatment protocols available for latex allergy.

Aortic stenosis with end-stage liver disease: prioritizing surgical and anesthetic therapies.

A 48-year-old man with end-stage liver disease and aortic stenosis (AS), was being evaluated for liver transplantation. This report focuses on the question of which medical problem to correct first, the end-stage liver disease or the AS. Risk factors for surgical correction of AS and liver transplantation are reviewed and discussed, and the surgical and anesthetic management strategies for this patient are outlined.

Optical nonlocalities and additional waves in epsilon-near-zero metamaterials.

We analyze the optical properties of plasmonic nanorod metamaterials in the epsilon-near-zero regime and show, both theoretically and experimentally, that the performance of these composites is strongly affected by nonlocal response of the effective permittivity tensor. We provide the evidence of interference between main and additional waves propagating in the room-temperature nanorod metamaterials and develop an analytical description of this phenomenon. Additional waves are present in the majority of low-loss epsilon-near-zero structures and should be explicitly considered when designing applications of epsilon-near-zero composites, as they represent a separate communication channel.

Optical transmission measurements of silver, silver-gold alloy and silver-gold segmented nanorods in thin film alumina.

Silver nanorods have been grown by electrodeposition into thin film porous alumina. Transmission measurements show two peaks related to the transverse and longitudinal resonance of the nanorods. The behaviour of the longitudinal resonance peak is found to vary with nanorod length and the spectral position to depend on nanorod diameter. As the distance between the nanorods is decreased a small blue-shift of the longitudinal peak is observed. Depositing a small gold cap on top of the silver nanorods causes a red-shift of the longitudinal peak whilst, conversely, the longitudinal peak of gold nanorod arrays is comparatively insensitive to the deposition of a silver cap. Gold-silver alloy nanorods were also deposited from a mixed salt bath and a linear dependence of the transverse peak position on alloy composition was observed.

Endotracheal tube location verified reliably by cuff palpation.

To verify a safe location of the endotracheal tube (ETT), palpation of the ETT at the sternal notch is a time-honored technique: After anesthetic induction and confirmation of orotracheal intubation, the patient's head is placed in a neutral position. The ETT is withdrawn or advanced while gentle, repetitive pressure is applied with the fingers at the level of the suprasternal notch. Simultaneously, the pilot balloon is held in the other hand. When the balloon distends from the pressure applied at the notch, the ETT is secured. We tested the efficacy of this technique in men and women who underwent general anesthesia. After the ETT was secured, the distance (in cm) from its tip to the upper incisors, that is, the length of ETT inserted, was measured to confirm its location relative to the carina. The study population consisted of 44 women and 38 men (n = 82) who ranged in age from 16 to 85 yr and in ASA physical status from I to IV. The size of the ETT tube for women ranged from 7.0 to 8.0 and for men, 7.0 to 8.5. Average distance from the tip of the ETT to teeth in women was 20.2 cm (range, 17-23) and in men 21.9 cm (range, 19-25). Average distance to the carina in women was 3 cm (range, 2-5) and in men 3.4 cm (range, 2-6). In this study, palpation of the ETT cuff effectively confirmed ETT location. The technique, which should not be used to verify endotracheal rather than bronchial intubation, should decrease the risk of bronchial intubation or impingement on the carina.

Somatosensory-evoked potentials during aortic coarctation repair.

OBJECTIVE: To determine the incidence of somatosensory-evoked potential (SSEP) changes and the interventions based on these changes during aortic coarctation repair. DESIGN: Retrospective review. SETTING: Single-institution, university hospital. PARTICIPANTS: Eighty-four children who had undergone surgical repair of aortic coarctation from January 1984 to May 1996. INTERVENTIONS: SSEPs were monitored in all patients throughout the procedure. A persistent decrease in amplitude greater than 50% from baseline was considered significant. Duration of SSEP changes in relation to the time course of surgical repair and whether a surgical or anesthetic intervention resulted from a change in SSEPs were documented. MEASUREMENTS AND MAIN RESULTS: Eighty-four patients underwent 87 surgical procedures. SSEP changes occurred in 40% of the procedures: 38.5% with repair and 15% with test clamp, with 9% occurring during both test clamp and repair. Interventions, which included repositioning the aortic cross-clamp, elevating blood pressure, and aborting surgery, occurred in 26.4% of all procedures based on SSEP changes. No patient sustained a neurologic deficit. CONCLUSION: This is the largest series to date describing the use of SSEPs in aortic coarctation repair. These SSEP changes were often immediately amenable to changes in surgical and anesthetic management. SSEP changes and interventions based on these changes occurred with a considerable frequency.