Shock outcome prediction before and after CPR: a comparative study of manual and automated active compression-decompression CPR.

We report on a study designed to compare the relative efficacy of manual CPR (M-CPR) and automated mechanical CPR (ACD-CPR) provided by an active compression-decompression (ACD) device. The ECG signals of out-of-hospital cardiac arrest patients of cardiac aetiology were analysed just prior to, and immediately after, cardiopulmonary resuscitation (CPR) to assess the likelihood of successful defibrillation at these time points. The cardioversion outcome prediction (COP) measure previously developed by our group was used to quantify the probability of return of spontaneous circulation (ROSC) after counter-shock and was used as a measure of the efficacy of CPR. An initial validation study using COP to predict shock outcome from the patient data set resulted in a performance of 60% specificity achieved at 100% sensitivity on a blind test of the data. This is comparable with previous studies and provided confidence in the robustness of the technique across hardware platforms. Significantly, the COP marker also displayed an ability to stratify according to outcomes: asystole, ventricular fibrillation (VF), pulseless electrical activity (PEA), normal sinus rhythm (NSR). We then used the validated COP marker to analyse the ECG data record just prior to and immediately after the chest compression segments. This was initially performed for 87 CPR segments where VF was both the pre- and post-CPR waveform. An increase in the mean COP values was found for both CPR types. A signed rank sum test found the increase due to manual CPR not to be significant (p>0.05) whereas the automated CPR was found to be significant (p<0.05). This increase was larger for the automated CPR (1.26, p=0.024) than for the manual CPR (0.99, p=0.124). These results indicate that the application of CPR does indeed provide beneficial preparation of the heart prior to defibrillation therapy whether manual or automated CPR is applied. The COP marker shows promise as a definitive, quantitative determinant of the immediate positive effect of both types of CPR regardless of the details of use. In work of a more exploratory nature we then used the validated COP marker to analyse the ECG pre- and post-CPR for all rhythm types (212 traces). We show a significant increase in the COP measure (p<0.001 in both cases) as indicated by a shift in the median COP marker distribution values. This increase was more pronounced for automated ACD-CPR than for manual CPR. However, a detailed statistical analysis carried out between the groups adjusted for pre-CPR value showed no significant difference between the two methods of CPR (p=0.20). Similarly, adjusting for length of CPR showed no significant difference between the groups. Secondary, subgroup analysis of the ECG according to the length of time for which CPR was performed showed that both types of CPR led to an increase in the likelihood of successful defibrillation after increasing durations of CPR, however results were less reliable after longer periods of continuous CPR.

Telomerase activity in the differential diagnosis of papillary carcinoma of the thyroid.

BACKGROUND: Although fine-needle aspiration (FNA) is 90% sensitive in the detection of papillary carcinoma (PC) of the thyroid, its specificity has been reported as low as 52%. Consequently, patients who have an FNA suspicious for PC may undergo operation for a benign process. The ribonucleoprotein telomerase has been noted to be activated in a wide variety of carcinomas. We examined 30 PCs for telomerase activity to determine whether this would be a useful adjunct to FNA in the diagnosis of lesions suspicious for PC. METHODS: Standard telomere repeat amplification protocol assays were performed on fresh frozen tissue samples from 30 PCs, 3 benign nodules, and 10 normal thyroids. RESULTS: Telomerase activity was documented in 20 of 30 (67%) of the PCs, 0 of 3 benign nodules, and 0 of 10 normal thyroids. In all, 11 of the 20 PCs had FNA cytology that was nondiagnostic of PC, and 2 of the benign nodules had FNA that was suspicious for PC. CONCLUSIONS: The telomerase assay appears useful in the distinction of benign from malignant thyroid lesions that have FNA suspicious for but not diagnostic of PC. On the basis of these findings, a prospective trial examining telomerase activity in FNAs suspicious for thyroid cancer has been initiated.

Investigating biological response in the UVB as a function of ozone variation using perturbation theory.

In order to determine a biological response to ultraviolet radiation, calculations of biologically weighted dose rates are required, which in turn involve the integral over wavelength of an action spectrum multiplied by appropriate surface flux data. To determine a biologically weighted dose rate accurately, a reasonable wavelength resolution is required, involving a full radiative transfer solution to be performed for each wavelength in order to obtain the surface flux information. If biologically weighted dose rates are needed as a function of ozone variation, then the number of radiative transfer solutions quickly makes a large number of ozone variations cumbersome. This paper shows that the perturbation theory developed for atmospheric radiative transfer by Box and co-workers can predict surface fluxes and hence biologically weighted dose rates for a large range of ozone variations very efficiently. The method is then extended to calculate radiation amplification factors. Results for biologically weighted dose rates are presented for a large range of solar zenith angles and ozone loadings using perturbation theory and a full radiative transfer code and show that the perturbation predictions never deviate very far from the radiative transfer solutions.

Treatment of elective mute behavior in two developmentally delayed children using modeling and contingency management.

Most classification schemes differentiate elective mutism from language problems seen in the developmentally delayed population. Two preschool developmentally delayed children were treated for speech reluctance using modeling and contingency management. Employing a multiple baseline across therapists, it was found that these treatment components were effective in increasing frequency of labeling behavior in both children. Results were maintained at follow-up. Generalization to new words and to spontaneous speech were also noted, and suggest that characteristics of elective mutism in this population may be similar to what is found in the general population.

A cost-effective weighing chamber for particulate matter filters.

Particulate matter (PM) is a ubiquitous air pollutant that has been receiving increasing attention in recent years due in part to the association between PM and a number of adverse health outcomes, including mortality and increases in emergency room visits and respiratory symptoms, as well as exacerbation of asthma and decrements in lung function. As a result, the ability to accurately sample ambient PM has become important, both to researchers and to regulatory agencies. The federal reference method for the determination of fine PM as PM2.5 in the atmosphere recommends that particle-sampling filters be conditioned and weighed in an environment with constant temperature and relative humidity (RH). It is also recommended that vibration, electrostatic charges, and contamination of the filters from laboratory air be minimized to reduce variability in filter weight measurements. These controls have typically been maintained in small, environmentally controlled "cleanrooms." As an alternative to constructing an elaborate cleanroom, we have designed, and presented in this paper, an inexpensive weighing chamber to maintain the necessary level of humidity control.

An evaluation of two methods for increasing self-initiated verbalizations in autistic children.

Three children with autism and mental retardation were treated for deficits in self-initiated speech. A novel treatment package employing visual cue fading was compared with a graduated time-delay procedure previously shown to be effective for increasing self-initiated language. Both treatments included training multiple self-initiated verbalizations using multiple therapists and settings. Both treatments were effective, with no differences in measures of acquisition of target phrases, maintenance of behavioral gains, acquisition with additional therapists and settings, and social validity.

Different mechanisms for Arabidopsis thaliana hybrid necrosis cases inferred from temperature responses.

Temperature is a major determinant of plant growth, development and success. Understanding how plants respond to temperature is particularly relevant in a warming climate. Plant immune responses are often suppressed above species-specific critical temperatures. This is also true for intraspecific hybrids of Arabidopsis thaliana that express hybrid necrosis due to inappropriate activation of the immune system caused by epistatic interactions between alleles from different genomes. The relationship between temperature and defence is unclear, largely due to a lack of studies that assess immune activation over a wide range of temperatures. To test whether the temperature-based suppression of ectopic immune activation in hybrids exhibits a linear or non-linear relationship, we characterised the molecular and morphological phenotypes of two different necrotic A. thaliana hybrids over a range of ecologically relevant temperatures. We found both linear and non-linear responses for expression of immunity markers and for morphological defects depending on the underlying genetic cause. This suggests that the influence of temperature on the trade-off between immunity and growth depends on the specific defence components involved.

Multiple-locus variable-number tandem-repeat analysis of meticillin-resistant Staphylococcus aureus discriminates within USA pulsed-field gel electrophoresis types.

Many isolates of meticillin-resistant Staphylococcus aureus (MRSA) are indistinguishable when compared using the standard pulsed-field gel electrophoresis (PFGE) typing method. This may present a problem when investigating local outbreaks of MRSA transmission in a healthcare setting. It also impedes investigation of the widely disseminated community-acquired MRSA (USA 300-0114) in the inpatient setting, which is displacing other traditional hospital-acquired PFGE types. Combination of methods, including multiple-locus sequence typing (MLST), spa typing and staphylococcal cassette chromosome mec (SCCmec) typing, have been used with, or in place of, PFGE to characterise MRSA for epidemiological purposes. These methods are technically challenging, time-consuming and expensive and are rarely feasible except in large laboratories in tertiary care medical centres. Another method, which is simpler and with faster turnaround time, is multiple-locus variable-number tandem-repeat analysis (MLVA). We investigated the utility of MLVA to distinguish common PFGE types. The results suggest that MLVA can be used to identify unrelated strains with identical PFGE patterns or confirm close genetic composition of linked isolates. MLVA could potentially be used in conjunction with PFGE to validate relationships, but further prospective evaluation of these relationships will be required in order to define the proper role, if any, for use of this method in hospital epidemiology.

Finite bandwidth and scattered light effects on the radiometric determination of atmospheric turbidity and the solar constant.

Multispectral solar radiometric measurements are routinely performed at a large number of sites, using equipment of varying degrees of sophistication. From the standard Langley plot technique, one may extract the total optical thickness of the atmosphere (and hence the aerosol component) plus the extraterrestrial solar flux. With increasing concern about possible climatic effects of increased turbidity, or changes in the solar constant, it is becoming more important to know the expected accuracy of these results. In this paper, we analytically examine the effects of finite filter bandwidth (in the absence of spectral lines) and find them to be less than one part in a thousand. This is compared with our earlier results on the effects of scattered light, which turns out to be typically an order of magnitude larger.

Information content analysis of aerosol remote-sensing experiments using singular function theory. 2: Scattering measurements.

We employ the singular function theory, which is the natural framework within which to discuss the analysis of first kind Fredholm integral equations, to analyze fully the information available from an aerosol aureole scattering experiment. This information is, of course, of two kinds: first, the number of pieces of information available for a given experimental error level and, second, the type (or location) of this information. To appreciate fully the latter, we apply this theory to the inversion of eleven synthetic data sets. These inversions are compared with those obtained previously from an extinction experiment.

Information content analysis of aerosol remote-sensing experiments using singular function theory. 1: Extinction measurements.

An important early step in any planned remote-sensing experiment is an analysis of the information content of the equations which will ultimately be inverted. In this paper, we employ the singular function theory, which is the natural framework within which to discuss the analysis of first kind Fredholm integral equations. Using this theory, we are able to fully analyze the information available from an aerosol extinction experiment. It is important to appreciate that this information is actually of two forms: first, the number of pieces of information available for a given experimental error level, and second, the type (or location) of this information. To fully appreciate the latter, we apply this theory to the inversion of eleven synthetic data sets, including three multimodal model size distributions.

Finite sun effect on the interpretation of solar aureole.

Although it is usually assumed that solar radiation falls on the earth's atmosphere in the form of plane waves, the finite angular size of the solar disk contradicts this assumption. For most purposes, this finite sun effect on computed or measured radiation quantities is negligible. However, in the region of the solar aureole, which is dominated by aerosol diffraction scattering, measurable effects may be obtained. In this paper, we show that the finite sun effect is related to derivatives of the scattering phase function and that a 1% effect may be obtained close to the sun if enough large particles are present in the atmosphere.

Atmospheric scattering corrections to solar radiometry.

Whenever a solar radiometer is used to measure direct solar radiation, some diffuse sky radiation invariably enters the detector's field of view along with the direct beam. Therefore, the atmospheric optical depth obtained by the use of Bouguer's transmission law (also called Beer-Lambert's law), that is valid only for direct radiation, needs to be corrected by taking account of the scattered radiation. In this paper we shall discuss the correction factors needed to account for the diffuse (i.e., singly and multiply scattered) radiation and the algorithms developed for retrieving aerosol size distribution from such measurements. For a radiometer with a small field of view (half-cone angle < 5 degrees ) and relatively clear skies (optical depths < 0.4), it is shown that the total diffuse contribution represents approximately 1% of the total intensity. It is assumed here that the main contributions to the diffuse radiation within the detector's view cone are due to single scattering by molecules and aerosols and multiple scattering by molecules alone, aerosol multiple scattering contributions being treated as negligibly small. The theory and the numerical results discussed in this paper will be helpful not only in making corrections to the measured optical depth data but also in designing improved solar radiometers.

Retrieval of aerosol size distributions by inversion of simulated aureole data in the presence of multiple scattering.

Inversion of solar almucantar data is a simple and practical method of obtaining aerosol size distributions. In this paper, we have inverted a number of sets of simulated data, using the standard single scattering approximation, to test the errors involved in ignoring multiple scattering. We have also inverted the data using two techniques: one, a modification of the method proposed by Deirmendjian and Sekera; and the other that of McPeters and Green. Inversion results strongly suggest that the accuracy of the retrieved size distribution can be significantly improved by use of our modified Deirmendjian-Sekera approach, in which multiple scattering by molecules is included along with single scattering by molecules and aerosols.

Relationship between two analytic inversion formulae for multispectral extinction data.

Recently Box and McKellar and Fymat have presented analytic inversion formulae for multispectral extinction data in the anomalous diffraction approximation. In this paper, we shall examine the relationship between these two formulae, and in the process we shall derive both the power series expansion and the asymptotic expansion for the extinction in this approximation.

Forwardscattering corrections for optical extinction measurements in aerosol media. 1: Monodispersions.

This paper, Part 1 of two papers, presents a parametric study of the forwardscattering corrections for experimentally measured optical extinction coefficients in homogeneous aerosol media, since some forwardscattered light invariably enters, along with the direct beam, into the finite aperture of the detector. Part 1 treats the case of monodispersions; Part 2, that of polydispersions. Forwardscattering is considered a single-scattering phenomenon, and the corrections are computed by two methods: one, using the exact Mie theory, and the other, the approximate Rayleigh diffraction formula. A parametric study of the dependence of the corrections on the particle size parameter, real and imaginary parts of the complex refractive index, and the half-angle of the detector's view cone has been carried out. The parameter ranges in which the results obtained by the approximate formulation agree well with those obtained by the Mie theory are also investigated. The agreement is especially good for small view cone angles and large particles and improves even more for slightly absorbing aerosol particles. Also discussed is the dependence of these corrections upon the experimental design of the transmission measurement systems.

Forwardscattering corrections for optical extinction measurements in aerosol media. 2: Polydispersions.

This paper, second of two parts, presents a parametric study of the forwardscattering corrections for experimentally measured optical extinction coefficients in polydisperse particulate media, since some forward scattered light invariably enters, along with the direct beam, into the finite aperture of the detector. Forwardscattering corrections are computed by two methods: (1) using the exact Mie theory, and (2) the approximate Rayleigh diffraction formula for spherical particles. A parametric study of the dependence of the corrections on mode radii, real and imaginary parts of the complex refractive index, and half-angle of the detector's view cone has been carried out for three different size distribution functions of the modified Gamma type. In addition, a study has been carried out to investigate the range of these parameters in which the approximate formulation is valid. The agreement is especially good for small-view cone angles and large particles, which improves significantly for slightly absorbing aerosol particles. Also discussed is the dependence of these corrections on the experimental design of the transmissometer systems.

Single and multiple scattering contributions to circumsolar radiation.

Single and multiple scattering contributions to the circumsolar radiation along the almucantar and sun vertical have been computed by a Gauss-Seidel solution to the radiative transfer equation. In the near forward direction, the multiple scattering contributions are significant for optical depths of the order of 0.4. However, the shape of the angular distribution of almucantar radiance up to 10 degrees appears less sensitive to multiple scattering. The results have been compared against an existing radiative transfer code.

Retrieval of the albedo and phase function from exiting radiances with radiative perturbation theory.

We use radiative perturbation theory to develop a retrieval technique for determining the radiative properties of a scattering medium, such as the Earth's atmosphere, based on measurements of the radiation emerging at either the top or bottom of the medium. In a previous paper [J. Quant. Spectrosc. Radiat. Transfer 54, 695 (1995)] we have shown the capacity of radiative perturbation theory to describe variations in exiting intensity as a linear combination of the parameters that characterize the scattering medium. Here we show that it is possible to set up a matrix relation such that the matrix inversion solves the inverse scattering problem. Using simulated data, we observe that the quality of the solution can be controlled by studying the singular values associated with the kernel matrix, obtaining in this way a stable solution, even in the presence of noise.

Information content of the kernel matrix for the phase function retrieval problem.

We investigate the information content of the radiation measurements to be used in the retrieval of the scattering properties of the atmosphere with the perturbation technique that we previously introduced. Applying this technique to different sets of data, we obtained solutions with varying accuracy. An analysis of these solutions shows that selecting linearly independent data in directions corresponding to small values of the scattering angle increases the number of pieces of information. (This result is in accord with conclusions reached by other researchers, based on a variety of criteria.) This information content should be largely independent of the method or methods employed to perform the inversion procedure.