Keratoconus: an analysis of corneal asymmetry

Background: Keratoconus, a non-inflammatory corneal ectasia, is reported to have bilateral involvement in over 90% of patients. The purpose of this study was to quantify the extent of asymmetry of disease at presentation to a regional corneal clinic.

Signatures of delayed detonation, asymmetry, and electron capture in the mid-infrared spectra of supernovae 2003hv and 2005df

We present mid-infrared (5.2-15.2 mu m) spectra of the Type Ia supernovae (SNe Ia) 2003hv and 2005df observed with the Spitzer Space Telescope. These are the first observed mid-infrared spectra of thermonuclear supernovae, and show strong emission from fine-structure lines of Ni, Co, S, and Ar. The detection of Ni emission in SN 2005df 135 days after the explosion provides direct observational evidence of high-density nuclear burning forming a significant amount of stable Ni in a SN Ia. The SN 2005df Ar lines also exhibit a two-pronged emission profile, implying that the Ar emission deviates significantly from spherical symmetry. The spectrum of SN 2003hv also shows signs of asymmetry, exhibiting blueshifted [Co (III)], which matches the blueshift of [Fe (II)] lines in nearly coeval near-infrared spectra. Finally, local thermodynamic equilibrium abundance estimates for the yield of radioactive Ni-56 give M-56Ni approximate to 0.5 M-circle dot, for SN 2003hv, but only M-56Ni approximate to 0.13-0.22 M-circle dot for the apparently subluminous SN 2005df, supporting the notion that the luminosity of SNe Ia is primarily a function of the radioactive 56Ni yield. The observed emission-line profiles in the SN 2005df spectrum indicate a chemically stratified ejecta structure, which matches the predictions of delayed detonation (DD) models, but is entirely incompatible with current three-dimensional deflagration models. Furthermore, the degree that this layering persists to the innermost regions of the supernova is difficult to explain even in a DD scenario, where the innermost ejecta are still the product of deflagration burning. Thus, while these results are roughly consistent with a delayed detonation, it is clear that a key piece of physics is still missing from our understanding of the earliest phases of SN Ia explosions.

Possible evidence of asymmetry in SN 2007rt, a type IIn supernova

An optical photometric and spectroscopic analysis of the slowly-evolving type IIn SN 2007rt is presented, covering a duration of 481 days after discovery. Its earliest spectrum, taken approximately 100 days after the explosion epoch, indicates the presence of a dense circumstellar medium, with which the supernova ejecta is interacting. This is supported by the slowly-evolving light curve. A notable feature in the spectrum of SN 2007rt is the presence of a broad He i 5875 line, not usually detected in type IIn supernovae. This may imply that the progenitor star has a high He/H ratio, having shed a significant portion of its hydrogen shell via mass-loss. An intermediate resolution spectrum reveals a narrow Ha P-Cygni profile, the absorption component of which has a width of 128 km s-1. This slow velocity suggests that the progenitor of SN 2007rt recently underwent mass-loss with wind speeds comparable to the lower limits of those detected in luminous blue variables. Asymmetries in the line profiles of H and He at early phases bears some resemblance to double-peaked features observed in a number of Ib/c spectra. These asymmetries may be indicative of an asymmetric or bipolar outflow or alternatively dust formation in the fast expanding ejecta. In addition, the late time spectrum, at over 240 days post-explosion, shows clear evidence for the presence of newly formed dust.

The Unification of Asymmetry Signatures of Type Ia Supernovae

We present a compilation of the geometry measures acquired using optical and IR spectroscopy and optical spectropolarimetry to probe the explosion geometry of Type Ia supernovae (SNe Ia). Polarization measurements are sensitive to asymmetries in the plane of the sky, whereas line profiles in nebular phase spectra are expected to trace asymmetries perpendicular to the plane of the sky. The combination of these two measures can overcome their respective projection effects, completely probing the structures of these events. For nine normal SNe Ia, we find that the polarization of Si II ?6355 at 5 days before maximum (p Si II ) is well correlated with its velocity evolution (\dot{v}_Si II), implying that \dot{v}_Si II is predominantly due to the asymmetry of the SNe. We find only a weak correlation between the polarization of Si II and the reported velocities (v neb) for peak emission of optical Fe II and Ni II lines in nebular spectra. Our sample is biased, with polarization measurements being only available for normal SNe that subsequently exhibited positive (i.e., redshifted) v neb. In unison these indicators are consistent with an explosion in which the outer layers are dominated by a spherical oxygen layer, mixed with an asymmetric distribution of intermediate-mass elements. The combination of spectroscopic and spectropolarimetric indicators suggests a single geometric configuration for normal SNe Ia, with some of the diversity of observed properties arising from orientation effects.

Illumination invariant facial recognition using a piecewise-constant lighting model

In this paper we demonstrate a simple and novel illumination model that can be used for illumination invariant facial recognition. This model requires no prior knowledge of the illumination conditions and can be used when there is only a single training image per-person. The proposed illumination model separates the effects of illumination over a small area of the face into two components; an additive component modelling the mean illumination and a multiplicative component, modelling the variance within the facial area. Illumination invariant facial recognition is performed in a piecewise manner, by splitting the face image into blocks, then normalizing the illumination within each block based on the new lighting model. The assumptions underlying this novel lighting model have been verified on the YaleB face database. We show that magnitude 2D Fourier features can be used as robust facial descriptors within the new lighting model. Using only a single training image per-person, our new method achieves high (in most cases 100%) identification accuracy on the YaleB, extended YaleB and CMU-PIE face databases.

Neonatal Facial Coding System for assessing postoperative pain in infants:item reduction is valid and feasible

The objectives of this study were to: (1). evaluate the validity of the Neonatal Facial Coding System (NFCS) for assessment of postoperative pain and (2). explore whether the number of NFCS facial actions could be reduced for assessing postoperative pain.

Bedside application of the Neonatal Facial Coding System in pain assessment of premature neonates

Assessment of infant pain is a pressing concern, especially within the context of neonatal intensive care where infants may be exposed to prolonged and repeated pain during lengthy hospitalization. In the present study the feasibility of carrying out the complete Neonatal Facial Coding System (NFCS) in real time at bedside, specifically reliability, construct and concurrent validity, was evaluated in a tertiary level Neonatal Intensive Care Unit (NICU). Heel lance was used as a model of procedural pain, and observed with n = 40 infants at 32 weeks gestational age. Infant sleep/wake state, NFCS facial activity and specific hand movements were coded during baseline, unwrap, swab, heel lance, squeezing and recovery events. Heart rate was recorded continuously and digitally sampled using a custom designed computer system. Repeated measures analysis of variance (ANOVA) showed statistically significant differences across events for facial activity (P <0.0001) and heart rate (P <0.0001). Planned comparisons showed facial activity unchanged during baseline, swab and unwrap, then increased significantly during heel lance (P <0.0001), increased further during squeezing (P <0.003), then decreased during recovery (P <0.0001). Systematic shifts in sleep/wake state were apparent. Rise in facial activity was consistent with increased heart rate, except that facial activity more closely paralleled initiation of the invasive event. Thus facial display was more specific to tissue damage compared with heart rate. Inter-observer reliability was high. Construct validity of the NFCS at bedside was demonstrated as invasive procedures were distinguished from tactile. While bedside coding of behavior does not permit raters to be blind to events, mechanical recording of heart rate allowed for an independent source of concurrent validation for bedside application of the NFCS scale.

The expression of pain in infants and toddlers:developmental changes in facial action

Age-related changes in the facial expression of pain during the first 18 months of life have important implications for our understanding of pain and pain assessment. We examined facial reactions video recorded during routine immunization injections in 75 infants stratified into 2-, 4-, 6-, 12-, and 18-month age groups. Two facial coding systems differing in the amount of detail extracted were applied to the records. In addition, parents completed a brief questionnaire that assessed child temperament and provided background information. Parents' efforts to soothe the children also were described. While there were consistencies in facial displays over the age groups, there also were differences on both measures of facial activity, indicating systematic variation in the nature and severity of distress. The least pain was expressed by the 4-month age group. Temperament was not related to the degree of pain expressed. Systematic variations in parental soothing behaviour indicated accommodation to the age of the child. Reasons for the differing patterns of facial activity are examined, with attention paid to the development of inhibitory mechanisms and the role of negative emotions such as anger and anxiety.

Judging pain in newborns:facial and cry determinants

Explored the facial and cry characteristics that adults use when judging an infant's pain. Sixteen women viewed videotaped reactions of 36 newborns subjected to noninvasive thigh rubs and vitamin K injections in the course of routine care and rated discomfort. The group mean interrater reliability was high. Detailed descriptions of the infants' facial reactions and cry sounds permitted specification of the determinants of distress judgments. Several facial variables (a brow bulge, eyes squeezed shut, and deepened nasolabial fold constellation, and taut tongue) accounted for 49% of the variance in ratings of affective discomfort after controlling for ratings of discomfort during a noninvasive event. In a separate analysis not including facial activity, several cry variables (formant frequency, latency to cry) also accounted for variance (38%) in ratings. When the facial and cry variables were considered together, cry variables added little to the prediction of ratings in comparison to facial variables. Cry would seem to command attention, but facial activity, rather than cry, can account for the major variations in adults' judgments of neonatal pain.

A comparison of two measures of facial activity during pain in the newborn child

Facial activity is strikingly visible in infants reacting to noxious events. Two measures that reduce this activity to composite events, the Neonatal Facial Coding System (NFCS) and the Facial Action Coding System (FACS), were used to examine facial expressions of 56 neonates responding to routine heel lancing for blood sampling purposes. The NFCS focuses upon a limited subset of all possible facial actions that had been identified previously as responsive to painful events, whereas the FACS is a comprehensive system that is inclusive of all facial actions. Descriptions of the facial expressions obtained from the two measurement systems were very similar, supporting the convergent validity of the shorter, more readily applied system. As well, the cluster of facial activity associated with pain in this sample, using either measure, was similar to the cluster of facial activity associated with pain in adults and other newborns, both full-term and preterm, providing construct validity for the position that the face encodes painful distress in infants and adults.