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Evaluation of an articulation-index based model for predicting the effects of adaptive frequency response hearing aids.

The Articulation Index (AI) was used to evaluate an "adaptive frequency response" (AFR) hearing aid with amplification characteristics that automatically change to become more high-pass with increasing levels of background noise. Speech intelligibility ratings of connected discourse by normal-hearing subjects were predicted well by an empirically derived AI transfer function. That transfer function was used to predict aided speech intelligibility ratings by 12 hearing-impaired subjects wearing a master hearing aid with the Argosy Manhattan Circuit enabled (AFR-on) or disabled (AFR-off). For all subjects, the AI predicted no improvements in speech intelligibility for the AFR-on versus AFR-off condition, and no significant improvements in rated intelligibility were observed. The ability of the AI to predict aided speech intelligibility varied across subjects. However, ratings from every hearing-impaired subject were related monotonically to AI. Therefore, AI calculations may be used to predict relative--but not absolute--levels of speech intelligibility produced under different amplification conditions.

Adult↗

[Predictive factors in social adaptation disorders in anorexic and bulimic patients].

A lifetime diagnosis of at least one anxiety disorder has been found in 13% to 75% of women with BN (Herzog, Keller, Sacks, Yeh, & Lavori, 1992; Schwalberg, Barlow, Alger, & Howard, 1992), and in 20% to 55% of women with AN, (Herzog et al., 1992, Laessle et al., 1989). Wittchen et al., 1998) have observed that the frequency and degree of disabilities and impairments associated with mental disorders in adolescence are strongly related to comorbidity (notably with anxiety disorders). However, as noted by Wonderlich et al., 1997, no study has compared ED individuals with and without comorbid anxiety disorders in terms of clinical or general functioning. The current study was designed to determine whether social avoidance symptoms and/or comorbid lifetime anxiety disorders were predictive factors of social disability in subjects with ED (AN or BN). We focused on two main dimensions of social adaptation, regarding social and professional life. 63 subjects with anorexia nervosa or bulimia nervosa were assessed for lifetime diagnoses of anxiety disorders, childhood history of separation anxiety disorder, social avoidance symptoms, and social disability. Sociodemographic characteristics, lifetime diagnoses of ED and anxiety disorders, and ages at onset of each disorder present, were assessed using the French version of the Composite International Diagnostic Interview (CIDI) (Robins et al., 1988; WHO, 1990). In addition, childhood history of separation anxiety disorder, not included in the CIDI, was assessed using the appropriate section of the Schedule for Schizophrenia and Affective Disorders Lifetime Version--Modified for the study of Anxiety Disorders (SADS-LA-R) (Endicott, Spitzer, 1978; Mannuzza, Fyer, Klein, 1985). Social anxiety symptoms were measured on Liebowitz Social Phobia Scale (Liebowitz, 1987). Social adjustment was assessed using a semi-structured interview, the Groningen Social Disabilities Schedule-Second version (GSDS-II) (Wiersma, De Jong, Ormel, & Kraaij Kamp, 1990). For each of the two outcome variables regarding disability, the Social role and the Occupational role, all subsets logistic regression analysis was performed in accordance to Hosmer and Lemeshow's guidelines (Hosmer and Lemeshow, 1989). Our total sample of 63 subjects included 29 subjects with AN restricting type (27 women, 2 men; 7% with a past history of BN) and 34 subjects with BN purging type (all women; 53% with history of a previous episode of AN). On the Groningen Social Disabilities Schedule, 86% of the anorexics and 65% of the bulimics had disability regarding the "social role", and 86% and 61%, respectively, disability regarding the "occupational role". Using all subsets logistic regression analyses, predictive factors of disability were: 1) for the social role, social avoidance symptom score (p < 0.002) and diagnosis of separation anxiety disorder (p < 0.01); 2) for the occupational role, number of lifetime anxiety disorders (p < 0.01) and diagnosis of separation anxiety disorder (p < 0.06). The present study clearly demonstrates that social avoidance and anxiety disorders are common and important features in the clinical presentation of subjects with AN or BN, and that they can have a negative impact on both their social and their occupational adaptation. Chronicity is a major risk in the ED, in terms of medical and sometimes lethal complications, but also because of the social consequences of these disorders. It is therefore important, in subjects with ED, to identify comorbid conditions linked to social disability, in order to improve global outcome. Recognizing and treating comorbid anxiety disorders in subjects with AN or BN could give better results than treating only the ED, in terms of social as well as global psychopathological outcome.

Adjustment Disorders↗

Exploration of linear modelling techniques and their combination with multivariate adaptive regression splines to predict gastro-intestinal absorption of drugs.

In general, linear modelling techniques such as multiple linear regression (MLR), principal component regression (PCR) and partial least squares (PLS), are used to model QSAR data. This type of data can be very complex and linear modelling techniques often model only a limited part of the information captured in the data. In this study, it was tried to combine linear techniques with the flexible non-linear technique multivariate adaptive regression splines (MARS). Models were built using an MLR model, combined with either a stepwise procedure or a genetic algorithm for variable selection, a PCR model or a PLS model as starting points for the MARS algorithm. The descriptive and predictive power of the models was evaluated in a QSAR context and compared to the performances of the individual linear models and the single MARS model. In general, the combined methods resulted in significant improvements compared to the linear models and can be considered valuable techniques in modelling complex QSAR data. For the used data set the best model was obtained using a combination of PLS and MARS. This combination resulted in a model with a Pearson correlation coefficient of 0.90 and a cross-validation error, evaluated with 10-fold cross-validation of 9.9%, pointing at good descriptive and high predictive properties.

Algorithms↗

The impact of high and low stress on the health of Lebanese families.

During the Lebanese war (1975-1991) families were subjected to a substantial number of war and nonwar life events that were shown to have a negative impact on family adaptation. The study was undertaken to classify and predict family adaptation outcomes in high and low perceived stress groups for war and nonwar life events. The study took the form of an analysis of cross-sectional data of families in Beirut. The cluster sample consisted of 438 families chosen at random. Variables included perceived stress for war and nonwar events, and health and interactional indicators of the outcome family adaptation assessed in terms of physical and psychological health, depression, and interpersonal and marital relationships. Families were classified into high/low stress based on their score for war and non-war life events. Based on discriminant function analysis, a significant difference existed between the high- and low-stress groups (for war, nonwar, and a combination of the two) on all predictor variables. Interpersonal relationships, physical health, and depression were the best predictors of membership in the high/low war stress groups. In the perceived nonwar stress groups, depression, interpersonal relationships, marital relations, and physical and psychological health were the best predictors separating high/low stress groups. When the combination score of war and nonwar stress was used, interpersonal relationships, physical health, depression, and marital relations were the best predictors distinguishing among the groups. Findings indicated a high degree of consistency in the prediction and classification of the high/low stress groups and for all stress categories. Families in the low-stress groups had a more positive adaptation than those in the high-stress groups and could be classified on the basis of their stress score. Families in the high-stress groups had more complaints than their counterparts in the low-stress groups. This classification may help mental health professionals understand how families adapt in response to normative and non-normative life situations.

Adaptation, Psychological↗

Dynamic predictive coding by the retina.

Retinal ganglion cells convey the visual image from the eye to the brain. They generally encode local differences in space and changes in time rather than the raw image intensity. This can be seen as a strategy of predictive coding, adapted through evolution to the average image statistics of the natural environment. Yet animals encounter many environments with visual statistics different from the average scene. Here we show that when this happens, the retina adjusts its processing dynamically. The spatio-temporal receptive fields of retinal ganglion cells change after a few seconds in a new environment. The changes are adaptive, in that the new receptive field improves predictive coding under the new image statistics. We show that a network model with plastic synapses can account for the large variety of observed adaptations.

Adaptation, Physiological↗

Whose quality of life? A commentary exploring discrepancies between health state evaluations of patients and the general public.

There is often a discrepancy between quality of life estimates from patients and the general public. These discrepancies are of concern to the disability community, who worry that the public does not understand how valuable life can be for people with disabilities; policy planners, who must decide whose quality of life estimates to use in economic analysis; and practitioners and patients facing difficult medical decisions, who may have to worry that people have difficulty imagining unfamiliar health states. We outline several factors that may contribute to these discrepancies. Discrepancies might occur because patients and the public interpret health state descriptions differently--for example, making different assumptions about the recency of onset of the health state, or about the presence of comorbidities. Discrepancies might also arise if patients adapt to illness and the public does not predict this adaptation; because of response shift in how people use quality of life scales; because of a focusing illusion whereby people forget to consider obvious aspects of unfamiliar health states; because of contrast effects, whereby negative life events make people less bothered by less severe negative life events; and because of different vantage points, with patients viewing their illness in terms of the benefits that would result from regaining health, while the public views the illness in terms of the costs associated with losing good health. Decisions about whose values to measure for the purposes of economic analyses, and how to measure discrepancies, should take these potential contributing factors into account.

Adaptation, Psychological↗

Predicting ethnic variation in adaptation to later life: styles of socioemotional functioning and constrained heterotypy.

It is an axiom of social gerontology that populations of older individuals become increasingly differentiated as they age. Adaptations to physical and social losses and the increased dependency that typically accompany greater age are likely to be similarly heterogeneous, with different individuals adjusting to the aging process in widely diverse ways. In this paper we consider how individuals with diverse emotional and regulatory profiles, different levels of religiosity, and varied patterns of social relatedness fare as they age. Specifically, we examine the relation between ethnicity and patterns of socioemotional adaptation in a large, ethnically diverse sample (N = 1118) of community-dwelling older adults. Cluster analysis was applied to 11 measures of socioemotional functioning. Ten qualitatively different profiles were extracted and then related to a measure of physical resiliency. Consistent with ethnographic and psychological theory, individuals from different ethnic backgrounds were unevenly distributed across the clusters. Resilient participants of African descent (African Americans, Jamaicans, Trinidadians, Barbadians) were more likely to manifest patterns of adaptation characterized by religious beliefs, while resilient US-born Whites and Immigrant Whites were more likely to be resilient as a result of non-religious social connectedness. Taken together, although these data underscore the diversity of adaptation to later life, we suggest that patterns of successful adaptation vary systematically across ethnic groups. Implications for the continued study of ethnicity in aging and directions for future research are given.

Adaptation, Psychological↗

A pharmacodynamic model to predict the time dependent adaptation of dopaminergic activity during constant concentrations of haloperidol.

The concentration-response relationship of the accumulation of brain homovanillic acid (HVA) has been studied by giving rats a shorter (12 h) and a longer (76 h) constant intravenous infusion of haloperidol, respectively, at rates aiming at different steady state blood concentrations of haloperidol of 5 to 30 ng mL-1. The observed response on brain HVA concentration vs increasing steady state blood concentration of the drug produced a bell-shaped type of curve during the 12 h infusion. When the infusion proceeded for 76 h a similar type of curve was obtained but it was shifted downwards compared with the 12 h infusion. The dopaminergic activity of the rat brain, as reflected by the HVA levels, therefore adapted to a lower activity during the prolonged exposure to haloperidol. To follow the time course of this adaptation, one steady state level of about 12 ng mL-1 was established and kept for 12, 28, 52 and 76 h. The result showed that the accumulation of brain HVA decreased over time compared with control animals given placebo. A pharmacodynamic model was set up to quantitatively describe the time-dependent adaptation of HVA accumulation in the whole rat brain during constant haloperidol administration. By fitting this model to all three sets of experimental data simultaneously, an adaptation half-time of about 38 h +/- 14 (s.d.) and a tolerance potency of about 7 ng mL-1 were obtained which could be used to calculate that, for example, at a constant blood level of 10 ng mL-1 haloperidol over 5 days the accumulation of brain HVA decreased by approximately 91% of the maximal decrease.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗

Prediction of impaired metabolic adaptation by antenatal Doppler studies in small for gestational age fetuses.

The increased risk of hypoglycaemia for infants who are small for gestational age (SGA) is well known, and further information regarding metabolic adaptation can be gained by examining the profiles of glucose and other metabolic fuels in such infants. Not all SGA infants experience hypoglycaemia, however, and the ability to identify, antenatally, those at most risk would be helpful for obstetric and neonatal management. This study investigated metabolic differences between two groups of SGA infants who had antenatal umbilical artery Doppler studies. Fourteen had end diastolic velocities (EDV) present and 11 had absent EDV. The absent EDV group had significantly lower non-esterified fatty acid (NEFA) concentrations at birth, and lower blood glucose and NEFA concentrations in the first six hours after birth. After the first day, few metabolic differences were found between the two groups. Antenatal Doppler studies may identify those SGA infants who fail to achieve neonatal metabolic adaptation and are most at risk of early neonatal hypoglycaemia.

Adaptation, Physiological↗

Commercial adaptation of ultrasonography to predict pork carcass composition from live animal and carcass measurements.

Live animal and carcass data were collected from market barrows and gilts (n = 120) slaughtered at a regional commercial slaughter facility to develop and test prediction equations to estimate carcass composition from live animal and carcass ultrasonic measurements. Data from 60 animals were used to develop these equations. Best results were obtained in predicting weight and percentage of boneless cuts (ham, loin, and shoulder) and less accuracy was obtained for predicting weight and ratio of trimmed, bone-in cuts. Independent variables analyzed for the live models were live weight, sex, ultrasonic fat at first rib, last rib, and last lumbar vertebra, and muscle depth at last rib. Independent variables for the carcass models included hot carcass weight, sex of carcass, and carcass ultrasonic measurements for fat at the first rib, last rib, last lumbar vertebra, and muscle depth at last rib. Equations were tested against an independent set of experimental animals (n = 60). Equations for predicting weight of lean cuts, boneless lean cuts, fat-standardized lean, and percentage of fat-standardized lean were most accurate from both live animal and carcass measurements with R2 values between .75 and .88. The results from this study, under commercial conditions, suggest that although live animal or carcass weight and sex were the greatest contributors to variation in carcass composition, ultrasonography can be a noninvasive means of differentiating value, especially for fat-standardized lean and weight of boneless cuts.

Adipose Tissue↗

Adapting best linear unbiased prediction (BLUP) for timely genetic evaluation: I. Progeny traits in a single contemporary group for each sex.

The first step of a procedure to partially circumvent the voluminous calculations with extremely large matrices for the usual algorithms for a BLUP (best linear unbiased prediction) approach is presented. This procedure, specific for a hierarchical portion of a model relevant to many animal breeding populations, is pertinent especially for polytocous species such as swine and poultry. For these, the occurrence of full-sib families makes the inclusion of dam effects in the model more necessary than in dairy or beef cattle models, where dam effects often are omitted. The formulas are derived for the hierarchical model for sires, dams within sires, individuals within full-sib family, and records within individuals, showing a relatively simple structure for such predictors. These formulas provide the basis for an alternative computing algorithm for obtaining evaluations having the statistical properties of best linear unbiased prediction. Formulas also are developed to approximate the prediction error variances for such models. Following this, the methodology for combining separate BLUP predictors, both error-independent and correlated, is developed.

Algorithms↗

Adapting best linear unbiased prediction (BLUP) for timely genetic evaluation: II. Progeny traits in multiple contemporary groups within a herd.

The second step of a procedure to partially circumvent the voluminous calculations for some BLUP (Best Linear Unbiased Prediction) computing algorithms for genetic evaluation is presented. In addition, the procedure allows timely evaluations of each contemporary group. This procedure is pertinent especially for polytocous species such as swine and poultry, for which the occurrence of full-sib families makes the inclusion of dam effects in the model necessary and tests are completed throughout the year. Formulas are developed for a model including sires, dams, individuals within full-sib families and records within individuals. This model has a fundamentally hierarchical structure but includes some cross-classification. The formulas for predictors combine information across contemporary groups within a herd and incorporate relationships between sires and(or) dams in that herd. Formulas to approximate prediction error variances also are developed.

Algorithms↗

[Mathematical modelling of the reactivity of analyzer systems during adaptation].

Information processing has been successfully applied to the prediction of the adaptation characteristics of various sensory analyzers. On the basis of mathematical treatment of the experimental data available in literature, time-constant values T and of the limit parameter I infinity required for prediction of adaptation course have been obtained. Formula have been derived for determining the dependence of these parameters on the luminance and wave-length of the light, on the concentration of the solution and the temperature of the stimulus. The results of computations are compared with the experimental data obtained by various authors.

Adaptation, Physiological↗

Effects of Training Goals and Goal Orientation Traits on Multidimensional Training Outcomes and Performance Adaptability.

This research examined the effects of mastery vs. performance training goals and learning and performance goal orientation traits on multidimensional outcomes of training. Training outcomes included declarative knowledge, knowledge structure coherence, training performance, and self-efficacy. We also examined the unique impact of the training outcomes on performance adaptability by predicting generalization to a more difficult and complex version of the task. The experiment involved 60 trainees learning a complex computer simulation over 2 days. The research model posited independent effects for training goals relative to goal orientation traits and independent contributions of training outcomes to the performance adaptability of trainees. The findings were consistent with the proposed model. In particular, self-efficacy and knowledge structure coherence made unique contributions to the prediction of performance adaptability after controlling for prior training performance and declarative knowledge. Implications and extensions are discussed. Copyright 2001 Academic Press.

Journal Article↗

Cerebellar contributions to locomotor adaptations during splitbelt treadmill walking.

Locomotor adaptability ranges from the simple and fast-acting to the complex and long-lasting and is a requirement for successful mobility in an unpredictable environment. Several neural structures, including the spinal cord, brainstem, cerebellum, and motor cortex, have been implicated in the control of various types of locomotor adaptation. However, it is not known which structures control which types of adaptation and the specific mechanisms by which the appropriate adjustments are made. Here, we used a splitbelt treadmill to test cerebellar contributions to two different forms of locomotor adaptation in humans. We found that cerebellar damage does not impair the ability to make reactive feedback-driven motor adaptations, but significantly disrupts predictive feedforward motor adaptations during splitbelt treadmill locomotion. Our results speak to two important aspects of locomotor control. First, we have demonstrated that different levels of locomotor adaptability are clearly dissociable. Second, the cerebellum seems to play an essential role in predictive but not reactive locomotor adjustments. We postulate that reactive adjustments may instead be predominantly controlled by lower neural centers, such as the spinal cord or brainstem.

Adaptation, Physiological↗

[The value of the prism adaptation test in determining the degree of squint surgery].

The angle of squint deviation was measured preoperatively before and after a prism adaptation of 1 day's duration in 50 esotropic and 45 exotropic patients. All had a deviation of 17 degrees or more under prismatic correction and were operated on by a recess-resect procedure of 10 mm on one eye. Postoperative measurements were done about 4 days and 6 weeks after surgery. In 58% of the esotropic and 37% of the exotropic patients, the initial deviation increased under prisms. This was found most often when normal retinal correspondence was present. There was a correlation between the effect of surgery with the change of deviation under prisms, particularly in normosensory esotropia and intermittent exotropia. Accordingly, the standard deviation of the surgical effect was smaller in this group, when it was calculated from the deviation under prisms in comparison to a calculation from the primarily measured angle. The influence of the preoperative deviation on the effect of a 10-mm recess-resect procedure was also found for the deviation under prisms and must therefore additionally be mentioned in the dosage of surgery. This retrospective study shows that preoperative prism adaptation improves predictability of the effect in squint surgery, at least in normosensory esotropia and intermittent exotropia. In patients with early-onset strabismus prism adaptation does not improve predictability, but higher dosage seems to be useful in cases with increased deviation under prisms and did not lead to over corrections. In this group the test represents an additional method for evaluation of the binocular sensory status.

Adolescent↗