Solar ultraviolet irradiation of human cornea, lens, and retina: equations of ocular irradiation

Photochemical damage of ocular tissues by solar radiation depends on the spectral composition of the radiation in the environment, the geometry of the coupling of that radiation to the eye, the spectral transmittances of the ocular components and any auxiliary lenses used, the spectral sensitivity of the irradiated tissue, the accumulated exposure dose, and the action of repair processes. This paper provides formulas for quantitative estimation of corneal, lenticular, and retinal UV irradiances from the sunlit environment under clear sky conditions. Applications of these formulas for ocular irradiation will be presented in subsequent papers for the cornea, lens, and retina, and the results will be evaluated using weighting functions for the sensitivity of ocular tissue.     

Automated off-line respiratory event detection for the study of postoperative apnea in infants

Previously, we presented automated methods for thoraco-abdominal asynchrony estimation and movement artifact detection in respiratory inductance plethysmography (RIP) signals. This paper combines and improves these methods to give a method for the automated, off-line detection of pause, movement artifact, and asynchrony. Simulation studies demonstrated that the new combined method is accurate and robust in the presence of noise. The new procedure was successfully applied to cardiorespiratory signals acquired postoperatively from infants in the recovery room. A comparison of the events detected with the automated method to those visually scored by an expert clinician demonstrated a higher agreement (κ = 0.52) than that amongst several human scorers (κ = 0.31) in a clinical study . The method provides the following advantages: first, it is fully automated; second, it is more efficient than visual scoring; third, the analysis is repeatable and standardized; fourth, it provides greater agreement with an expert scorer compared to the agreement between trained scorers; fifth, it is amenable to online detection; and lastly, it is applicable to uncalibrated RIP signals. Examples of applications include respiratory monitoring of postsurgical patients and sleep studies.     

A nonlinear model for context-dependent modulation of the binocular VOR

Studies on the behavior of the vestibulo-ocular reflex (VOR) reveal that the monocular reflex gain is adjusted according to target position relative to each eye. In this paper, we present a nonlinear approach in modeling the viewing-context dependency of the slow-phase angular VOR. We show that including appropriate nonlinearities in the responses of premotor neurons in the brainstem is sufficient to account for the online modulation of the VOR with target position. This approach allows very complex behaviors in response to sensory patterns without resorting to currently assumed cortical computations. A local premotor topology with nonlinear properties has repercussions in the study of all ocular reflexes, since it implies context dependent dynamics in all behavioral responses (pursuit, optokinetic, VOR, saccades, etc.) that share this network. Local nonlinearities in spinal circuits could similarly influence the context dependence of other motor systems (such as stretch reflex modulation during rhythmic walking).     

Identification of halothane genotypes by calcium accumulation and their meat quality using live pigs

The three halothane genotypes (NN, Nn, and nm) were identified by measuring the capacity for Ca²⁺ accumulation by sarcoplasmic reticulum in whole muscle homogenate preparations of M. longissimus dorsi with a Ca²⁺ specific electrode at 35°C. Significant differences (P < 0·001) in deterioration (%) of Ca²⁺ accumulation, 12% for NN, 35% for Nn, and 81% for nn pigs, were observed after ageing the whole muscle homogenate preparations for 24 h in ice.

Predictions of meat quality in live pigs (n = 34) based on the values for water-holding capacity, assessed as fluid (g/0·5 g wet wt LD), and pH (fluid) by using small biopsy LD samples (Cheah et al. 1993) were performed on all the halothane genotypes. The halothane genotype NN (n = 11) showed a fluid value of 0·37 ± 0·01 and a pH (fluid) value of 6·62 ± 0·03 as compared with 0·61 ± 0·02 and 5·84 ± 0·04, respectively, for the halothane genotype nn (n = 13). The Nn pigs (n = 10) showed fluid (0·49 ± 0·03) and pH (fluid) (6·19 ± 0·11) values between those values observed for the two homozygotes (NN and nn). Predictions of meat quality in live pigs from biopsy LD muscles were confirmed from assessments on post-mortem LD muscles based on pH₁ and fibre optic probe (FOP) measurements.

The extent of deterioration (%) in Ca²⁺ accumulation showed high correlations with fluid (r = −0·861) and pH (fluid) (r = −0·831) in the biopsy LD samples, and with pH₁ (r = 0·663), FOP (r = −0·812), and drip (%) loss (r = −0·777) in the post-mortem LD samples.     

Improvement of the uniformity and dipole ferromagnetism in Co nanodots assemblies on Pb/Si(111) via step tuned dimensionality variation

We fabricated quasi-one-dimensional Co nanochain assemblies and two-dimensional Co nanodot assemblies on Pb/Si(111) substrates by step decoration. The morphology and magnetic properties of these two kinds of Co nanodot assemblies were investigated by in situ scanning tunneling microscopy and magneto-optical Kerr effect measurements. It was found that the steps cannot only improve the uniformity of the Co nanodots, but also increase the critical temperature T(c). Monte Carlo simulation indicates that the ferromagnetism mainly originates from the dipolar interactions and the critical temperature T(c) can be enhanced by introducing an in-plane uniaxial magnetic anisotropy via the step tuned dimensionality variation of the nanodot assemblies.