Evaluation of the malaria threat at the multipurpose range complex, Yongp'yong, Republic of Korea

As part of an operational effort to control the transmission of malaria after its reemergence in the Republic of Korea, a number of U.S. military and Korean civilian health workers assessed the situation at a large training site where two cases had been transmitted. The vector mosquitoes (Anopheles sinensis) probably had a limited flight range (< 1 km) in this situation based on low numbers in permanent light traps and biting collections at the billeting area compared with collections from light traps and larval surveys where the mosquito was abundant. The threat of malaria was proven by the presence of infected local Korean residents (13 of 105 sampled). However, only a small proportion of U.S. soldiers (39 of 78 surveyed) at the training site used personal protective measures. Further efforts should include improved techniques for informing and motivating soldiers to use personal protective measures and cooperation with Korean authorities to perform vector control in civilian areas bordering the training area.

The cancer amputee and sexuality

To the person experiencing amputation, the loss of a limb has a serious psychosexual impact. Whatever the age, the surgical procedure itself, pain, deformity, inability to perform simple customary acts, economic threat, and many other problems impose on the person facing the loss of their limb. Commonly, concentration is focused on functional abilities during and after prosthetic rehabilitation, and care taken to preserve the person's sexuality is often omitted. Major limb amputation can cause a decrease in self-esteem and body image due to perceived mutation, and this in turn can create emotional hurdles for both the patient and partner. Several potential problems such as the mechanics of body positioning during sex play, balance and movement, and phantom pain sensations can alter sexual function. Added difficulties include chemotherapy-induced neuropathies and enforced isolation because of limited mobility. Although these various disabling maladies may require alterations in a sexual relationship, sex drive and desire usually remain intact. Specific assessment techniques and interventions must be made available to enable the nurse to discuss sexual concerns at all stages of cancer and its treatment. As well, we must not fail to see alternatives to stereotypical behavior and acknowledge each patient's unique sexual identify.

Validation of the PASE in older adults with knee pain and physical disability

PURPOSE

To examine the validity of the Physical Activity Scale for the Elderly (PASE) among individuals with disability.

METHODS

A sample of 471 participants (mean age = 71.36) in an epidemiological study of chronic knee pain completed the PASE and self-report measures of knee pain, perceived physical function, satisfaction with physical function, and importance of physical function. A 6-min walk test and an isokinetic assessment of knee strength were also administered.

RESULTS

PASE scores were significantly correlated in expected directions with performance on the 6-min walk, knee strength, frequency of knee pain during transfer, and perceived difficulty with physical functioning. Gender and age were identified as significant moderators of PASE scores and the scale's construct validity was supported by testing a conceptually driven hypothesis regarding patterns of physical activity.

CONCLUSIONS

These results support the PASE's validity for the assessment of physical activity among older adults with pain and disability.

Temporary brittle bone disease: a true entity?

Temporary brittle bone disease is a recently described phenotype of increased fracture susceptibility in the first year of life in which there are multiple unexplained fractures without evidence of other internal or external injury. Most child abuse experts do not accept the existence of temporary brittle bone disease and presume these cases are child abuse. The author reviewed 26 cases of infants with multiple unexplained fractures that fit the criteria of temporary brittle bone disease and studied nine of them with either computed tomography or radiographic bone density measurements. The results show a striking association between temporary brittle bone disease and decreased fetal movement, usually from intrauterine confinement, and low bone density measurements in eight of the nine infants. The association with decreased fetal movement and intrauterine confinement is in keeping with the mechanostat-mechanical load theory of bone formation. The author feels that temporary brittle bone disease is a real entity and that historical information related to decreased fetal movement or intrauterine confinement and the use of bone density measurements can be helpful in making this diagnosis.

Functional status, assistance, and the risk of a community-based move

This study examined the effects of declining functional status and the availability of assistance on community-based residential mobility. Wolinsky and colleagues (1993), using data from the 1984, 1986, and 1988 waves of the Longitudinal Study on Aging, reported other transitions that result from increased health demand, namely those of nursing home placement and death. Using their functional health scales and recently available statistical techniques, we performed a two-stage analysis within a health behavior conceptual framework. We conclude that older adults who report several cognitive limitations in the absence of assistance in the home are more likely to make residential changes. Additionally, we determined that the independent effects of cognitive and lower body deterioration trigger, in this case, community-based moves even when adjusting for the effect of baseline levels of functional health and other factors in the model. Our analysis extends the earlier findings of Wolinsky and colleagues to encompass residential change as an ecological outcome of health decline in old age.

Is diabetic nephropathy inherited? Studies of glomerular structure in type 1 diabetic sibling pairs

Only a minority of patients with type 1 diabetes develop diabetic nephropathy (DN). Poor glycemic control cannot fully explain DN risk, and family studies suggest genetic susceptibility factors. To understand familial DN concordance, we evaluated glomerular structure in families with type 1 diabetic sibling pairs. Kidney function and biopsy studies were performed in 21 probands (P) (first to develop diabetes) and 21 siblings (S) (second to develop diabetes), most with normal urinary albumin excretion rates (UAER). Glomerular structure was measured by morphometry. Intrafamilial correlation was estimated by one-way random-effects ANOVA and by mixed-effects ANOVA, adjusting for age and duration of diabetes. Diabetes duration was, by definition, longer in P than in S, while age and sex were similar. HbA1c over 5 years and blood pressure were not different in P and S and were without familial effect. UAER was greater in P than in S (P < 0.05), with strong familial effect (P = 0.03). A strong concordance among siblings for mesangial fractional volume (P < or = 0.01) remained significant after adjustment for diabetes duration and age (P = 0.04). Results were similar for mesangial cell (P = 0.01; adjusted P = 0.04) and mesangial matrix fractional volumes (P < 0.01; adjusted P = 0.06). There was also clustering of the patterns of glomerular lesions. For example, if P had relatively marked glomerular basement membrane thickening compared with mesangial matrix expansion, S had a similar pattern (chi2, P < 0.025). Strong concordance in severity and patterns of glomerular lesions in type 1 diabetic siblings, despite lack of concordance in glycemia, supports an important role for genetic factors in DN risk.

1996 Remington lecture: modeling multivariate longitudinal data that are incomplete

PURPOSE

We describe the impact that missing data may have on model selection for longitudinal multivariate data.

METHODS

Maximum likelihood was used to fit several models to ultrasonographic measurements from the Asymptomatic Carotid Artery Progression Study (ACAPS). Graphical techniques were used to examine evidence concerning the underlying missing data mechanisms associated with each model.

RESULTS

Using statistical methodology that addressed missing data substantially increased the statistical efficiency of our analysis of ultrasonographic data. Only complex models that included segment-specific parameterizations for longitudinal correlations appeared to allow missing data to be assumed to occur at random.

CONCLUSION

Ignoring the nature of missing data in conducting statistical analyses can have serious consequences when missingness is not rare. It may be necessary to fit models of high dimension with maximum likelihood techniques to address missing data appropriately, however these approaches may improve statistical efficiency.

Temporary brittle bone disease: association with decreased fetal movement and osteopenia

Infants who present with multiple unexplained fractures pose a difficult diagnostic dilemma of child abuse versus intrinsic bone disease. Temporary brittle bone disease is a recently described disease characterized by a transient bone weakness in the first year of life which presents with multiple, unexplained fractures that can be confused with child abuse. The purpose of this study was to determine if there are common, historical features in infants with unexplained fractures that might suggest a basis for the fractures, and to determine if bone density measurements might indicate that such infants have low bone density. Medical records were reviewed in 33 infants who were referred for consultation for multiple unexplained fractures in which the parents and other caregivers denied wrongdoing. In 9 of the infants, radiographic absorptiometry and/or computed tomography bone density studies were performed. In 26 of these infants the diagnosis of temporary brittle bone disease was made. A normal collagen test was found in 17 of the 26 infants studied; 9 infants did not have a collagen test because the diagnosis of osteogenesis imperfecta was considered highly unlikely. In 25 of them there was a history of decreased fetal movement and/or intrauterine confinement. Bone density, as judged by plain X-ray films, was normal in all 26 cases, but when formally measured by radiographic absorptiometry or computed tomography, the bone density measurements were low in 8 of the 9 infants studied. These findings implicate decreased fetal movement and intrauterine confinement as contributing factors to temporary brittle bone disease and suggest that normal, unconstrained fetal movement during pregnancy is important for normal fetal bone formation. These findings support the model that bone formation and strength are dependent on the mechanical load placed on the bone. The results also demonstrate the usefulness of bone density measurements in evaluating the infant with multiple unexplained fractures to help distinguish nonaccidental injury from intrinsic bone disease.

Bone density measurements by computed tomography in osteogenesis imperfecta type I

The objectives of this study were (1) to determine whether there are differences in bone density in children versus adults with osteogenesis imperfecta type I (OI-type I) using computed tomography (CT) bone density measurements, (2) to determine whether there are differences in bone density between normal infants and infants with OI-type I using CT bone density measurements and (3) to determine whether CT bone density measurements could be helpful in investigating the infant with unexplained fractures. CT bone density measurements determine both the cortical bone density (CBD) and the trabecular bone density (TBD). CT bone density was determined using the OsteoQuant in 14 individuals with OI-type I who ranged in ages from 8 months to 45 years. The control groups consisted of over 1000 normal individuals, mostly adults, and included 7 normal infants who ranged in age from 10 months to 27 months. One of the individuals with OI-type I was a 4-month-old infant with multiple, unexplained fractures who had no other features of OI-type I and whose parents were accused of child abuse. Infants and children with OI-type I had low CBD and low TBD compared with normal controls, whereas adults with OI-type I had low TBD and high CBD when compared with controls. The one infant with multiple unexplained fractures and no other features of OI-type I had a bone density profile suggesting OI-type I with a low TBD and low CBD. Subsequent collagen analysis showed biochemical evidence of OI-type I. Individuals with OI-type I have abnormal CT bone density profiles that evolve over time from a low CBD and low TBD during infancy and childhood to a high CBD and low TBD during adulthood. This may explain the decreased frequency of fractures in individuals with OI-type I in adulthood compared with childhood. Individuals with OI-type I can present with only multiple unexplained fractures and have no other clinical features to strongly suggest the diagnosis. CT bone density measurements can be helpful in these atypical cases of OI-type I and should be considered in the investigation of the infant with unexplained fractures to help distinguish intrinsic bone disease from child abuse.

Laparoscopic placement of electrodes for diaphragm pacing using stimulation to locate the phrenic nerve motor points

Laparoscopic mapping of the phrenic nerve motor points using test stimulation was conducted for the implant of epimysial electrodes for diaphragm pacing in dogs. Both visual assessment of muscle activation and measurements of recruitment were useful for identifying an implant location resulting in a mean electrode placement approximately 14 mm from the phrenic nerve motor points in 16 dogs. Postmortem analysis of the stimulus test site locations and corresponding recruitment curves suggested that the phrenic nerve motor points could be predicted during the laparoscopic procedure to within 4.5 mm of the anatomical motor point.

Occupational injuries among adolescents in Washington State, 1988-1991

BACKGROUND

To characterize work-related injuries and illnesses in minors.

METHODS

We analyzed Washington State workers' compensation claims from 1988 through 1991.

RESULTS

There were 17,800 claims among adolescents from age 11 through 17 years accepted in the 4-year period, including three occupational fatalities, 22 amputations, and 464 fractures; 89% of all injuries occurred among the 16- and 17-year-olds. Claims were most frequent in restaurants, food stores, service industry, other retail and wholesale trade, and agriculture. Washington State census data were used for denominator in calculating injury rates for adolescents and adults. The crude injury rate for 16- and 17-year-olds employed at the time of the census was similar to that seen among adults (9.0 vs 10.4 per 100 workers), despite that minors work fewer hours per year. The rate among boys was almost twice that seen among girls (11.7 vs. 6.4 per 100 workers). Highest rates, per 100 workers, were in public administration (27.0), construction (21.1), agriculture (11.4), and restaurants (11.0). Using census data for those working anytime over the course of the year and adjusted for the number of hours worked, the injury rate for 16- and 17-year-olds was 19.4/100 full time equivalents compared with 10.6 of 100 full-time equivalents for adults. Most injuries were lacerations, sprains and strains, contusions, and burns.

CONCLUSIONS

Public health policy and injury prevention strategies for working adolescents should be developed and implemented.

The relative weighting of acoustic properties in the perception of [s] + stop clusters by children and adults

We examined the perceptual weighting by children and adults of the acoustic properties specifying complete closure of the vocal tract following a syllable-initial [s]. Experiment 1 was a novel manipulation of previously examined acoustic properties (duration of a silent gap and first formant transition) and showed that children weight the first formant transition more than adults. Experiment 2, an acoustic analysis of naturally produced say and stay, revealed that, contrary to expectations, a burst can be present in stay and that first formant transitions do not necessarily distinguish say and stay in natural tokens. Experiment 3 manipulated natural speech portions to create stimuli that varied primarily in the duration of the silent gap and in the presence or absence of a stop burst, and showed that children weight these stop bursts less than adults. Taken together, the perception experiments support claims that children integrate multiple acoustic properties as adults do, but that they weight dynamic properties of the signal more than adults and weight static properties less.

The timing of change: patterns in transitions in functional status among elderly persons

Data from the Longitudinal Study on Aging (LSOA) were analyzed to describe the heterogeneity of functional status transitions over 2-years (single-state model), and to explore whether changes in status in the previous two to four year period enhance the prediction of a subsequent transition (two-state model). Multivariate logistic regression with a robust estimate of variance was used to analyze a 7-category nominal response of: functional status (4 levels), institutionalization, death, and missing. Weighted percentages for functional status transitions and stability (unchanged status) showed that unchanged or improved functioning were at least as common as death or worsened functional status. Initial disability level, morbidities, and self-rated health were the strongest predictors of disability status after 2-years. The two-state model revealed that a previous transition (positive or negative) increases the risk for a subsequent transition, independent of initial disability level. The predictive and explanatory quality of the two-state model is substantially improved over single-state models, particularly from its ability to identify subgroups of individuals with marked functional status instability.

Rationale, design, and baseline characteristics of the Prospective Randomized Evaluation of the Vascular Effects of Norvasc Trial (PREVENT)

The Prospective Randomized Evaluation of the Vascular Effects of Norvasc Trial is the first angiographic clinical trial to be designed to test whether an agent can slow or even reverse the progression of early coronary atherosclerosis in patients with documented disease. In addition, a subset of patients are undergoing carotid ultrasound examinations, providing a unique opportunity to assess and correlate disease progression in 2 arterial beds.

Time course analysis of the discriminative stimulus effects of the optical isomers of 3,4-methylenedioxymethamphetamine (MDMA)

The present study examined the discriminative stimulus effects of the MDMA optical isomers administered at different presession injection intervals. In the first experiment, male Sprague-Dawley rats were trained in a two-lever, food-reinforced operant procedure to discriminate either (+)-MDMA (1.25 mg/kg) or (-)-MDMA (3.50 mg kg) at either 20 or 90 min following injection. Animals administered (+)-MDMA or saline 90 min before training sessions failed to attain the discrimination criteria after 73 training sessions, whereas (-)-MDMA successfully established discriminative stimulus control at both the 20 min and the 90 min postinjection intervals. (+)-Amphetamine did not substitute for either isomer, although a significant amount of drug-appropriate responding occurred in animals trained to discriminate (+)-MDMA at 20 min and (-)-MDMA at 90 min. Sch 39166 partially reduced the discrimination of (+)-MDMA at 20 min and (-)-MDMA at 90 min, although this effect was not dose dependent. Sch 39166 had no effect on animals trained to discriminate (-)-MDMA at 20 min. Haloperidol did not alter the discrimination of (+)-MDMA at 20 min but partially reduced the discriminative stimulus control of (-)-MDMA at 20 min and (-)-MDMA at 90 min. Fenfluramine substituted for both isomers of MDMA. Pirenpirone completely blocked the discriminative stimulus effects of (-)-MDMA at 20 min, although (+)-MDMA at 20 min and (-)-MDMA at 90 min were only partly blocked. WAY 100,135 had little effect on drug-appropriate responding; however, the discrimination of (+)-MDMA at 20 min was partly reduced by this 5-HT1A antagonist. In a second experiment, rats trained to discriminate (+)-MDMA (1.5 mg/kg) or (-)-MDMA (3.0 mg/kg) from saline were administered substitution tests with both isomers 20, 60, 90 and 120 min after injection. Results confirmed those of the first experiment that (+)-MDMA appears to have a shorter duration of action than (-)-MDMA. These results are discussed in light of the training doses employed.

Benefits of linkage to the National Death Index in the Longitudinal Study of Aging

To reduce the potential bias resulting from differential loss to follow-up in the Longitudinal Study of Aging (LSOA), information obtained from household contact methods was supplemented with information from the National Death Index (NDI). This article examines the degree of agreement in the vital status data from two sources (reinterview contacts and the NDI system) and evaluates the potential gains of using the NDI data as a supplement to define participants' vital status. Results reveal that NDI information, used to supplement reinterview information, can substantially reduce bias due to the differential loss of participants to follow-up. Reliance on reinterview information alone was less likely to capture those deaths occurring in study participants who at the initial contact lived alone, were below the poverty index, were interviewed without use of a proxy, did not supply a phone number, and did not own a home.

Developmental weighting shifts for noise components of fricative-vowel syllables

Previous studies have convincingly shown that the weight assigned to vocalic formant transitions in decisions of fricative identity for fricative-vowel syllables decreases with development. Although these same studies suggested a developmental increase in the weight assigned to the noise spectrum, the role of the aperiodic-noise portions of the signals in these fricative decisions have not been as well-studied. The purpose of these experiments was to examine more closely developmental shifts in the weight assigned to the aperiodic-noise components of the signals in decisions of syllable-initial fricative identity. Two experiments used noises varying along continua from a clear /s/ percept to a clear /[symbol: see text]/ percept. In experiment 1, these noises were created by combining /s/ and /[symbol: see text]/ noises produced by a human vocal tract at different amplitude ratios, a process that resulted in stimuli differing primarily in the amplitude of a relatively low-frequency (roughly 2.2-kHz) peak. In experiment 2, noises that varied only in the amplitude of a similar low-frequency peak were created with a software synthesizer. Both experiments used synthetic /a/ and /u/ portions, and efforts were made to minimize possible contributions of vocalic formant transitions to fricative labeling. Children and adults labeled the resulting stimuli as /s/ vowel or /[symbol: see text]/ vowel. Combined results of the two experiments showed that children's responses were less influenced than those of adults by the amplitude of the low-frequency peak of fricative noises.

Assessment of the discriminative stimulus effects of the D3 dopamine antagonist PNU-99194A in rats: comparison with psychomotor stimulants

The present study examined the discriminative stimulus effects of the D3 dopamine receptor antagonist PNU-99194A [5,6-di-methoxy-2-(dipropylamino)indan-hydrochloride] in male Sprague-Dawley rats. Eight rats were trained to discriminate cocaine (10 mg/kg, i.p.) from saline in a two-choice, water-reinforced drug discrimination procedure. In tests of stimulus generalization, PNU-99194A (1.25-40.0 mg/kg, s.c. and i.p.) did not substitute for cocaine. PNU-99194A (5.0-20 mg/kg) also did not significantly block the discrimination of cocaine (10 mg/kg), nor did it potentiate a low dose (1.25 mg/kg) of cocaine. A separate group of eight rats were trained to discriminate PNU-99194A from saline. These subjects met the discrimination criterion within an average of 68 (S.E.M. = 6.5) training sessions; the ED50 for PNU-99194A was 2.6 mg/kg. In stimulus generalization tests, cocaine (1.25-10 mg/kg) did not substitute for PNU-99194A, when administered by either i.p. or by s.c. injection. In addition, neither amphetamine (0.25-1.0 mg/kg) nor caffeine (8.0-64 mg/kg) produced stimulus generalization in these rats. These results indicate that D3 receptors do not play a critical role in the discriminative stimulus effects of cocaine. Furthermore, although PNU-99194A is capable of establishing and maintaining discriminative stimulus control in rats, the effects of this D3-preferring antagonist are dissimilar from those of psychomotor stimulants. Given the unique behavioral profile of D3 receptor antagonists, the potential utility of these agents as adjunctive treatments for psychostimulant abuse is discussed.

Occurrence of Vine Decline Diseases of Melons in Honduras

A survey of vine decline diseases of melons (Cucumis melo L.) was conducted on three geographically separate farms (12 fields) in the area of San Lorenzo, Honduras, during the spring of 1996. Symptoms were typical of the vine declines in that the leaves began yellowing and collapsing in the crown just prior to harvest and the decline radiated outward. Crown lesions, typical of many of the vine declines, were observed infrequently. Most plants exhibited no crown lesion. Roots exhibited brown lesions and root corking, and were generally lacking root hairs, although the roots were not macerated. Fruit were small sized, low in sugars, and sunburned. Isolations were made from the crown area, primary root, and secondary roots of affected plants by excising 3- to 5-mm pieces and surface sterilizing for 30 to 60 s with 0.5% sodium hypochlorite. Four tissue pieces from each plant part were placed on 2.0% water agar plus 0.1 g of streptomycin sulfate per liter and their identity maintained. Plates were examined for fungal growth daily for 5 days and hyphal tips from all colonies were transferred to potato dextrose agar and Synthetischer nährstoffärmer agar (2) to allow for sporulation. Rhizoctonia solani Kühn was the predominant fungus isolated from affected plants in several fields, with an incidence as high as 75%. A Pythium sp. was isolated from primary and secondary roots of 50% of the plants on the Santa Rosa farm. Vines exhibiting tan to light brown crown lesions either on one side of the vine or encompassing the crown, but without gumming, always produced colonies of Fusarium semitectum Berk. & Ravenel. Fusarium solani (Mart.) Appel & Wollenweb. emend. W. C. Snyder & H. N. Hans. was isolated from roots of more than 30% of the plants, although this is not unusually high. Crown lesions typical of charcoal rot were observed in some fields, with Macrophomina phaseolina (Tassi) Goidanich being isolated from 65% of the plants in one field. Charcoal rot was a minor problem in all fields but one. Didymella bryoniae (Auersw.) Rehm was not isolated from any of the plants. A Stagonospora-like fungus, which has been demonstrated recently as a potential contributor to vine decline (1), was isolated on 17% of the plants from five fields on the Embarcadero Farm. Monosporascus cannonballus Pollack & Uecker was isolated infrequently in one field on the Santa Rosa Farm. This is the first report of M. cannonballus and a Stagonospora-like fungus in Honduras. References: (1) M. E. Miller et al. Phytopathology 86:S3, 1996. (2) H. I. Nirenberg. Mitt. Biol. Bundesanst. Land Forstwirtsch. Berlin-Dahlem. 169:1, 1976.

Occurrence of Vine Decline Diseases of Muskmelon in Guatemala

Central American countries have become major production areas of melons (Cucumis melo L.) destined for export to Europe and the United States during the winter months. Double cropping in the same fields year after year has created serious vine decline diseases in melons grown in the Capco area of Guatemala. Vines typically appear healthy until the fruit are approaching maturity, when the crown leaves begin to turn yellow and collapse and the decline gradually radiates outward. There was evidence of slightly water-soaked lesions in the crown of some plants; however, the symptoms were not similar to charcoal rot or gummy stem blight. The roots exhibited some decay, lesions, and discoloration, but were not macerated and rotten. A minimum of 10 affected plants were collected from each of nine fields in the Capco area of Guatemala. Isolations were made from the crown area, primary root, and secondary roots of selected plants by excising 3- to 5-mm pieces and surface sterilizing them for 30 to 60 s with 0.5% sodium hypochlorite. The isolations were made on 2% water agar plus 0.1 g of streptomycin sulfate per liter. Plates were examined for fungal growth daily for 5 days with hyphal tips from all colonies transferred to potato dextrose agar and Synthetischer nährstoffärmer agar (2) and allowed to sporulate. Isolations revealed the presence of several fungi capable of causing vine decline or suspected of being involved in the vine decline complex. Rhizoctonia solani Kühn and Fusarium semitectum Berk. & Ravenel were isolated from more than 50% of plants in some fields. F. semitectum, R. solani, and a Stagonospora-like fungus were isolated from 38, 18, and 17% of the total plants, respectively. R. solani was isolated from the crown more often than from the roots, but its role is not understood. With one exception, F. semitectum was always isolated from the crown area, which may suggest a more significant role in the vine decline complex than suspected previously. The Stagonospora-like fungus, isolated from 30% of the plants from one field, has been reported as a pathogen of cantaloupe that may contribute to the vine decline complex (1). Monosporascus cannonballus Pollack & Uecker and Fusarium oxysporum Schlechtend.:Fr. emend. W. C. Snyder & H. N. Hans. were isolated from 60% of the plants from one field. It was the only field in which M. cannonballus was isolated. Plectosporium tabacinum (van Beyma) M. E. Palm, W. Gams et Nirenberg, a cucurbit pathogen, was isolated infrequently. This is the first report of M. cannonballus, P. tabacinum, and the Stagonospora-like fungus in Guatemala. References: (1) M. E. Miller et al. Phytopathology 86:S3, 1996. (2) H. I. Nirenberg. Mitt. Biol. Bundesanst. Land Forstwirtsch. Berlin-Dahlem. 169:1, 1976.

Predicting developmental shifts in perceptual weighting schemes

Recent models of developmental changes in speech perception suggest that the weights assigned to acoustic properties change as children gain experience with a native language. Empirical evidence supports this position, but few suggestions have been offered as to what guides this shift. These three experiments were designed to improve our ability to predict how perceptual weighting schemes change with development. The specific hypothesis explored was twofold: (1) the weight assigned by adults to any one acoustic property differs across phonetic environments according to how informative that property is in each environment; and (2) the weight assigned by children to any one acoustic property differs less across phonetic environments because children have not fully learned the patterns of covariation between phonetic informativeness and environment for each property. Experiment 1 replicated previous findings of age-related differences in the weights assigned to noise spectra and formant transitions in labeling of syllable-initial fricatives (/s/ or /[symbol: see text]/). In experiment 2 the variation in F3-onset frequency associated with place of fricative constriction was eliminated. This property differs more (i.e., is more informative) in /u/ than in /a/. Accordingly adults' transition effect was reduced more for /u/ than for /a/ from experiment 1. Children's transition effect was similarly reduced across vowel environments. In experiment 3, F3-onset frequency was appropriately manipulated for both vowels, and adults transition effect increased more for /u/ than for /a/ from experiment 2. The increase in children's transition effect was more similar across vowels. We conclude that the children had not fully learned how information provided by F3 transitions varies across /a/ and /u/ environments, and suggest that developmental weighting shifts may be guided by children learning the relation between phonetic informativeness and environment.