Modeling early warning signs of possible Amazon Forest dieback.

Deforestation of the Amazon may reach a critical point where abrupt declines in rainfall could cause widespread forest dieback.

Testing simultaneously different covariance block diagonal structures - the multi-sample case.

In this work a likelihood ratio test which allows to test simultaneously if, several covariance matrices are equal and block diagonal with different specific structures in the diagonal blocks, is developed. The distribution of the likelihood ratio statistic is studied and the expression of its hth null moment are derived. In order to make the test useful in practical terms, near-exact approximations are developed for the likelihood ratio statistic. A practical application to real data set together with numerical studies and simulations are provided in order illustrate the applicability of the test and also to assess the precision of the near-exact approximations developed.

Life cycle differences among Brazilian sandflies of the Lutzomyia longipalpis sibling species complex.

The developmental cycles of five Brazilian populations of the Lutzomyia longipalpis Lutz & Neiva species complex (Diptera: Psychodidae) were compared under laboratory conditions. Three of the populations were derived from insects collected in allopatric sites at Natal (Rio Grande do Norte State), Jacobina (Bahia State) and Lapinha Cave (Minas Gerais State). The other two originated from Sobral (Ceará State), where the males of two sympatric species can be distinguished by the presence of one (1S) or two (2S) pairs of abdominal spots. The results of the present study clearly show that all three populations whose males produce C16 pheromones and use pulse-type copulation songs (Jacobina, Lapinha Cave and Sobral 1S) are more easily adapted to the colonization conditions used in our laboratory, producing larger egg batches, with higher survival and an overall faster developmental cycle. This contrasts with populations producing C20 male pheromones and using burst-type copulation songs (Natal and Sobral 2S) that produce smaller egg batches, have higher oviposition mortality and a slower rate of development under identical laboratory conditions. In conclusion, these phenological differences are a further indication of the differentiation of the siblings within the Lu. longipalpis species complex.

The relationship of the acquisition of manual signs to severity of aphasia: a training study.

To investigate the relationship between success in the acquisition of signs and the degree of severity of aphasic impairment 12 chronic severely aphasic subjects participated in a training program for the acquisition of a vocabulary of manual signs. The results demonstrate a clear and significant relationship between severity of aphasia and success in the acquisition and generalization of manual signs. The results also indicate that there may be a threshold of severity of aphasia below which acquisition is negligible. Discussion is presented relative to the theoretical, clinical, and methodological implications of these findings.

Acquisition and generalization of simple manual sign grammars by aphasic subjects.

The present study investigated the acquisition and generalization of manual sign combinations in four moderately to severely aphasic subjects. Two experiments were conducted: In the first, matrices were employed to train agent-action-object and action-object combinations and monitor generalization. In the second experiment, subjects were trained to combine a different set of single signs into sign combinations (agent-action-object, action-object) that could be used to describe two pictures while generalization was monitored in a third. Results of experiment 1 demonstrated that the two least severely aphasic subjects were able to acquire and generalize all of the sign combinations presented in the training matrices. In the second experiment, although the subjects rapidly acquired single signs and combinations, additional training was required for the subjects to produce the sign combinations to describe the two pictures and no generalization was noted in the third untrained picture. It is concluded that success in manual sign training programs is related to severity of aphasia; that aphasic subjects' propositional use of manual signs rarely follows simple acquisition; and that generalization to untrained stimuli or environments does not occur without additional training.

Cholesteryl ester storage disease. Report of a case.

Cholesteryl ester storage disease (CESD) is a rare disorder of familial incidence characterized by the accumulation of cholesteryl ester and triglycerides in the liver, intestine and bone marrow. Until now only 21 cases have been reported in the literature. We present a 9 months old girl presenting with increased abdominal girth. She had normal liver function tests and increased cholesterol and triglycerides serum levels. The liver biopsy showed many cholesterol cristals seen as needle shaped cristals under polarized light. This is the youngest patient being diagnosed clinically in the literature.

Effects of iconicity, motoric complexity, and linguistic function on sign acquisition in severe aphasia.

The influence of three features of manual signs (iconicity, motoric complexity, linguistic function) on their successful acquisition by aphasic subjects was investigated. 12 severe chronic aphasic subjects were presented 37 signs in a training program for the production of manual signs. Analysis indicates that the three signs features affected the successful acquisition of signs. As a group the subjects acquired a larger percentage of high and medium iconic than of low iconic signs; a larger percentage of low and medium motorically complex signs than high; and a larger percentage of verb than noun or adjective signs. The implications of these findings with regard to selecting a manual sign vocabulary for training are discussed.

Concurrent validity of the Kaufman Hand Movement Test as a measure of limb apraxia.

The concurrent validity of the Kaufman Hand Movement Test as a measure of limb apraxia was investigated. For 23 adult aphasic subjects, a Pearson r of 0.84 was obtained between scores on this test and on the Limb Apraxia Test, a battery of tasks often used in the assessment of limb apraxia. The Kaufman test is a shorter and simpler test to administer than the Limb Apraxia Test. The concurrent validity of the Kaufman test encourages its use in the assessment of limb apraxia.

An investigation of a method of simplified scoring for the Kaufman Hand Movements test as a measure of limb apraxia.

A simplified, 3-category method for scoring the Kaufman Hand Movements test was devised to replace a previously used, more complex 21-category scoring method. The concurrent validity and diagnostic sensitivity of the rescored test as a measure of limb apraxia were investigated in a reanalysis of the test protocols of 23 aphasic adults. Using the Limb Apraxia Test as the criterion measure, a Pearson r of .71 and predictive validity of 100% were obtained. These results encourage further investigation of the Kaufman Hand Movements test as an efficient measure of limb apraxia.

Working memory and discourse production abilities following closed-head injury.

PRIMARY OBJECTIVES: This study investigated the relationship between working memory (WM) and narrative discourse production in individuals with closed head injury (CHI). It was hypothesized that those individuals with higher performance on tests of WM would demonstrate better performance on measures of discourse production. RESEARCH DESIGN: Correlation coefficients were calculated among five discourse measures from two story narratives and scores from three sub-tests of the Wechsler Memory Scale (WMS). METHODS AND PROCEDURES: Fifty-five individuals with moderate-to-severe CHI were studied. Participants included 16 females and 39 males ranging in age from 16-69. Narrative discourse samples were elicited from all participants under two conditions: story retelling and story generation. MAIN OUTCOMES AND RESULTS: The results revealed a number of modest, significant correlations (r=0.29-0.39, p<0.05) between sub-tests of the WMS and measures of discourse production. CONCLUSIONS: Results supported the hypothesis. Story elicitation task differences, limitations of using simple memory span tests as indices of WM and clinical implications of the relationship between WM and discourse production are discussed.

Microlinguistic deficits in the narrative discourse of adults with traumatic brain injury.

BACKGROUND: Recent studies of microlinguistic impairments in the narrative discourse of adults with traumatic brain injury (TBI) have applied syntactic analyses, with some noting no deficits and others specific problems with sentence formulation. An alternative approach to examining the microlinguistic dysfunction in the discourse of individuals with TBI is through the use of propositional analysis. The advantage of propositional analysis is that it enables one to assess semantic complexity of utterances apart from sentence structure and grammaticality. AIMS: The present study applied propositional analysis to the story narratives of participants with TBI and participants with no brain injury (NBI). Specifically, the mean number of propositions within a sentence was tallied, in other words the participants' ability to insert multiple ideas into single surface sentences. It was hypothesized that the participants with TBI would produce fewer propositions per sentence because of organizational problems than the participants with NBI, regardless of level of education. METHODS AND PROCEDURES: Two story narratives (retelling and generation) previously elicited from the two participant groups (TBI (n = 53) and NBI (n = 42)) were analysed. For each language sample, the number of propositions was tallied and divided by the number of T-units. The resulting number, the propositional complexity index (PCI), was the average number of predicates per sentence. OUTCOMES AND RESULTS: Results indicated that the group with TBI produced significantly fewer propositions per T-unit. CONCLUSIONS: The present findings are in harmony with the notion that the participants with TBI studied presented with impairments of both micro- and macrolinguistic processes involved with the organization of semantic information in discourse. Clinical implications are discussed.

Sign acquisition and use following traumatic brain injury: case report.

A case report is presented of an aphasic patient whose oral communication skills remained nonfunctional eight months after a traumatic head injury. After several unsuccessful attempts at using a variety of augmentative communication devices, manual signing was attempted. Several signs believed to be useful for communicating the patient's needs and wants were selected. The signs were introduced in a three-stage training procedure: imitation of a sign model, pointing to a picture of the concept signed, and producing the sign when presented with the pictured concept. A sign item was considered to be acquired when the patient had progressed through all three of the training stages. The patient acquired 47 signs over a five-month period, but was unable to use these signs in spontaneous, self-initiated communication. These findings illustrate the vast gap that exists between learning to produce a sign in response to a stimulus and using those signs for functional communication. The distinction between sign acquisition and sign use has largely been ignored in previous investigations of sign training with aphasic patients. Programming for generalization of acquired signs is a logical next step for future research on this topic.

Incidence and nature of dysphagia in polio survivors.

Questionnaires pertaining to swallowing function were mailed to 220 members of postpolio support groups in Connecticut. Of the 109 responses, 80 individuals reported having no difficulty with swallowing, while 29 reported having either intermittent or consistent swallowing problems. Twenty-one of the 29 were seen for videofluoroscopic swallowing studies and pulmonary function testing. The swallowing studies showed that 43% of these individuals had difficulty with bolus control, 19% with delayed swallow response, and 81% with decreased pharyngeal transit. Although none of these individuals were observed to aspirate, two were judged to be at significant risk. Incidence of dysphagia within the group of polio survivors was estimated to be approximately 18%. Seventeen of the 20 postpolio subjects with dysphagia also demonstrated decreased breathing capacity. Although moderately to severely depressed values in the pulmonary function measures accompanied moderate dysphagia in certain postpolio individuals, reduced values in these same measures were also present in individuals with minimal swallowing dysfunction. Therefore, although impaired breathing may complicate swallowing dysfunction and vice versa, it does not appear that one can be predicated from the other. Management of dysphagia in postpolio individuals is discussed.

Dysphagia in postpolio sequelae: report of three cases.

Findings on three postpolio sequelae patients referred for swallowing evaluations are presented. The first patient, a 67-year-old man more than 60 years post onset of polio, complained of frequent coughing and the sensation of foods becoming stuck in his throat during meals. Videofluoroscopic swallowing exam revealed reduced pharyngeal peristalsis and liquid pooling in the pyriform sinus. The second patient, a 59-year-old woman, was more than 30 years post onset of polio and was referred because of progressive dysphagia and hoarseness in the past three years. Videofluoroscopy revealed reduced strength of the oral musculature and reduced pharyngeal peristalsis with pooling of liquids in the pyriform sinus. The last patient, a 50-year-old woman more than 40 years post onset of polio, reported having difficulty with foods sticking in her throat. Swallowing exam revealed a delayed swallowing reflex and reduced pharyngeal peristalsis. Although none of the patients was observed to aspirate, all were considered to be at risk because of the gradual build-up of foods in the pharynx. Noninvasive management procedures and the importance of stress testing the swallowing mechanisms of such patients are discussed. Longitudinal follow-up with these individuals is recommended.

The use of discourse analyses for the evaluation of higher level traumatically brain-injured adults.

Higher level traumatically brain-injured (TBI) adults often present a challenge in assessment as well as in the measurement of recovery. Traditional clinical measures of language abilities have not been adequate to identify and describe precisely what is deviant about their communication. Assessment has generally consisted of aphasia tests and measures of general cognitive abilities. Although such measures may be sensitive to deficits in lower level TBI patients or those in the early stages of recovery, their usefulness with higher functioning patients is questionable due to the often subtle nature of their residual communication problems. An overview of discourse analyses is presented and recent applications of these procedures with TBI patients reviewed.

Impairments of discourse abilities and executive functions in traumatically brain-injured adults.

Preliminary findings from an ongoing investigation of the potential relationship between narrative discourse performance and executive functions in adults with traumatic brain injuries (TBI) are reported. Narrative stories were elicited from 32 adults with TBI. Stories were analysed at three levels: sentence production, intersentential cohesive adequacy, and story episode structure. These measures were then correlated with scores from the Wisconsin Card Sorting Test (WCST), the primary measure of executive function. A significant correlation was noted between a factor score from the WCST and the measure of story structure, but not sentence production or cohesive adequacy. These results suggest that executive functions may be a promising avenue to pursue in the search for underlying causal factors of narrative discourse dysfunction and, therefore to better delineate the nature of communicative deficits secondary to TBI.

Treatment efficacy: cognitive-communicative disorders resulting from traumatic brain injury in adults.

Traumatic brain injuries (TBI) may result in a broad array of cognitive-communicative impairments. Cognitive-communicative impairments are the result of deficits in linguistic and nonlinguistic cognitive functions. The speech-language pathologist functions as a member of the multidisciplinary team of professionals that collaboratively assess and treat individuals with TBI. The role of the speech-language pathologist includes assessment of all aspects of communication, as well as the communicative implications of cognitive deficits, and swallowing; treatment planning and programming, as determined by the individual's stage of recovery; client and family training/counseling; and interdisciplinary consultation. The effectiveness of speech and language intervention for specific cognitive deficits (e.g., attention, memory, executive functions) as well as general issues of social-skills training and early intervention are illustrated by scientific and clinical evidence from group-treatment and single-subject studies as well as case studies.

Discourse analyses with closed head injured adults: evidence for differing patterns of deficits.

To better characterize the verbal impairments of higher level closed head injured (CHI) adults, we used narrative stories to longitudinally sample their discourse abilities. Stories were analyzed at the levels of intersentential cohesion and story grammar. Two differing patterns of deficits that emerged are described. In the first, a CHI subject demonstrated excessive verbalization characterized by poorly organized, but task-appropriate, content. In the second, a CHI subject demonstrated fair to good organization but little appropriate content. Prognostically, the presence of appropriate, although disorganized, content was an early indication that the subject was able to appreciate potential relationships of characters in the stimulus picture. The second pattern represented a more severe cognitive dysfunction. This subject's attempts at stories, although well organized, were merely elaborate descriptions of the picture. Discourse analyses appear to be well suited for the assessment of CHI adults.

The assessment of limb apraxia: an investigation of task effects and their cause.

To test the effects of variations in the structure of tasks used to assess limb apraxia, eight tasks--differing in their modes of elicitation (tactile, verbal, visual, imitation) and/or types of movement elicited (transitive, intransitive, meaningless)--were administered to 25 carefully selected subjects with idiomotor limb apraxia. When standardized scores (based on the performance of 10 nonneurologically impaired control subjects) were used to measure the differences between tasks, no clinically significant task effects were found. Additional investigation was made of two causal hypotheses regarding the processes underlying limb apractic performance. The results of factor analyses and a search for double dissociations among individual subjects were consistent with the (severity) hypothesis that differences in task performances (raw scores) reflect degrees of task difficulty; and they failed to support the (disconnection) hypothesis that posits separate and independent neural/mental processes underlying task performances.