Mosquito surveillance in the Demilitarized Zone, Republic of Korea, during an outbreak of Plasmodium vivax malaria in 1996 and 1997

Since 1993, more than 2,000 cases of vivax malaria have occurred in the Republic of Korea in an epidemic that ended nearly 20 malaria-free years. Most malaria has occurred in the northwestern part of the country, mainly affecting Korean military personnel. As a part of an operational surveillance effort, we sampled mosquitoes in and near the Demilitarized Zone (Paju County, Kyonggi Province) during the last 2 wk of July in 1996 and from May 15 to September 10 in 1997. The 1st year, landing collections were done at 5 different sites; the 2nd year, carbon-dioxide-baited light traps at 5 sites, larval collections in 10 adjacent fields, and landing collections at 1 site in the Demilitarized Zone were performed weekly. Of 17 species collected, Anopheles sinensis was consistently the most abundant mosquito, comprising 79-96% of mosquitoes. The diel pattern of biting by An. sinensis varied by location and season, with the majority of individuals biting late at night during warm weather (>20 degrees C) and early at night during cool weather. In contrast, Aedes vexans nipponii (the 2nd most abundant species) bit in the greatest numbers at the same time all season, from 2000 to 2300 h. Among the correlates with abundance of An. sinensis were average nighttime temperature 2 wk previous to the night in question, wind late at night (negatively correlated), and apparent size of the moon (negatively correlated). The data showed that the exact number of An. sinensis biting could not be estimated from numbers collected in carbon-dioxide-baited light traps. On the other hand, a threshold of 15 An. sinensis per trap night corresponded (88% accuracy) to a threshold of 12 mosquitoes biting 2 adjacent collectors per night. Larval collections were also significantly correlated with landing collections, despite inexact sampling methods and separation of the larval habitat from the site where landing collections were performed. Operational entomology assets using nighttime temperature records, carbon-dioxide-baited light traps, and larval collections should be able to target their efforts in Korea more efficiently.

Mixed effects logistic regression models for longitudinal ordinal functional response data with multiple-cause drop-out from the longitudinal study of aging

In the context of analyzing ordinal functional limitation responses from the Longitudinal Study of Aging, we investigate the association between current functional limitation and previous year's limitation and its modification by physical activity and multiple causes of drop-out. We accommodate the longitudinal nature of the multiple causes of informative drop-out (death and unknown loss-to-follow-up) with a mixed effects logistic model. Under the proposed model with a random intercept and slope, the ordinal functional outcome and multiple discrete time survival profiles share a common random effect structure. This shared parameter selection model assumes that the multiple causes of drop-out are conditionally independent of the functional limitation outcome given the underlying random effect representing an individual's trajectory of general health status across time. Although it is not possible to fully assess the adequacy of this assumption, we assess the robustness of the approach by varying the assumptions underlying the proposed model, such as the random effects distribution and the drop-out component. It appears that between-subject differences in initial functional limitation are strongly associated with future functional limitation and that this association is stronger for those who do not have physical activity regardless of the random effects and informative drop-out specifications. In contrast, the association between current functional limitation and previous trajectory of functional status within an individual is weaker and more sensitive to changes in the random effects and drop-out assumptions.

First Report of Leaf Blight of Onion Caused by Xanthomonas campestris in the Continental United States

In March 1998, a leaf blight of onion (Allium cepa L. '1015') was found on many plants in a plot on the Texas A&M Agricultural Experiment Station in Weslaco. The symptoms were longitudinal chlorotic areas on one side of the leaf, containing sunken, elliptical necrotic lesions. Affected leaves ultimately died. Chlorotic lesions were swabbed with 70% ethanol, and tissue from beneath the epidermis was placed in a drop sterile water for 20 min. Drops were streaked on nutrient agar and incubated at 30°C. Isolations yielded gram-negative, rod-shaped bacteria that formed dark yellow, gummy colonies on yeast dextrose carbonate agar medium, hydrolyzed starch, and had a single, polar flagellum. Analysis of fatty acid methyl ester (FAME) profiles, using the Microbial Identification System (MIS, version 4.15; Microbial Identification, Newark, DE), done at the Texas Plant Disease Diagnostic Laboratory, College Station, identified nine isolates as Xanthomonas campestris (similarity indices of 0.31 to 0.54). Tests at the University of Florida supported this identification: FAME profiles using MIS version 3.9 gave similarity indices of 0.89 to 0.95, and profiles using Biolog GN Microplates, MicroLog database release 3.50 (Biolog, Hayward, CA), gave similarity indices of 0.03 to 0.76. Leaves (15 to 20 cm long) of potted onions (cv. 1015 at the five- to six-leaf stage) were infiltrated with a suspension of bacteria (10⁷ CFU per ml), using a needle and syringe. Plants were maintained in mist chamber in a greenhouse at 24°C. Water-soaking and development of pale green color of the inoculated leaf occurred after 2 days, followed by death after 4 days. There were no symptoms on leaves inoculated with sterile water. Pathogenicity tests on four isolates were repeated once. Bacteria were reisolated on nutrient agar from symptomatic tissue but not from controls. In the field plot, disease severity did not increase as season progressed nor were there any symptoms on bulbs. Symptoms were not observed on onion during the 1999 season. X. campestris was first reported on onion from Hawaii (1). This is the first report of this pathogen on onion in the continental United States. Reference: (1) A. M. Alvarez et al. Phytopathology 68:1132, 1978.

cDNA probes for detection of specific dsRNAs from the fungal pathogen, Monosporascus cannonballus

Monosporascus cannonballus is an ascomycete fungus that is the causative agent of Monosporascus root rot/vine decline, a serious disease of muskmelon and watermelon. Double-stranded RNA (dsRNA) was identified in approximately 60% of M. cannonballus isolates recovered from infected muskmelon plants in 1993. After repeated laboratory transfer on culture media, the majority of the isolates harboring dsRNAs developed degenerate culture phenotypes and showed reduced virulence (hypovirulence) to muskmelon. Initially, dsRNA purification and cDNA synthesis were attempted in three M. cannonballus isolates harboring dsRNAs. However, numerous difficulties were encountered due to the stable, double-stranded nature of the dsRNAs and contamination of the preparations by fungal rRNA. Several purification and cDNA protocols were evaluated and eventually modified into methods that were ultimately highly effective for cloning dsRNAs from M. cannonballus. The cDNAs derived from purified dsRNA preparations were cloned into a pUC119 plasmid vector and amplified in Escherichia coli. Nine cDNA clones were identified that are specific for medium-sized (ca. 3 kbp) dsRNAs associated with M. cannonballus isolate Ca91-17(96+). The methods used to make the cDNA clones of the dsRNAs in M. cannonballus may be useful for those working on fungal dsRNAs. In addition, these cDNAs may be useful for identifying dsRNAs associated with the hypovirulence phenotype.

The effect of segmental order on fricative labeling by children and adults

We examined whether children modify their perceptual weighting strategies for speech on the basis of the order of segments within a syllable, as adults do. To this end, fricative-vowel (FV) and vowel-fricative (VF) syllables were constructed with synthetic noises from an/[symbol: see text]/-to-/s/continuum combined with natural/a/and/u/portions with transitions appropriate for a preceding or a following /[symbol: see text]/or/s/. Stimuli were played in their original order to adults and children (ages of 7 and 5 years) in Experiment 1 and in reversed order in Experiment 2. The results for adults and, to a lesser extent, those for 7-year-olds replicated earlier results showing that adults assign different perceptual weights to acoustic properties, depending on segmental order. In contrast, results for 5-year-olds suggested that these listeners applied the same strategies during fricative labeling, regardless of segmental order. Thus, the flexibility to modify perceptual weighting strategies for speech according to segmental order apparently emerges with experience.

Distinct subcellular localization patterns contribute to functional specificity of the Cln2 and Cln3 cyclins of Saccharomyces cerevisiae

The G(1) cyclins of budding yeast drive cell cycle initiation by different mechanisms, but the molecular basis of their specificity is unknown. Here we test the hypothesis that the functional specificity of G(1) cyclins is due to differential subcellular localization. As shown by indirect immunofluorescence and biochemical fractionation, Cln3p localization appears to be primarily nuclear, with the most obvious accumulation of Cln3p to the nuclei of large budded cells. In contrast, Cln2p localizes to the cytoplasm. We were able to shift localization patterns of truncated Cln3p by the addition of nuclear localization and nuclear export signals, and we found that nuclear localization drives a Cln3p-like functional profile, while cytoplasmic localization leads to a partial shift to a Cln2p-like functional profile. Therefore, forcing Cln3p into a Cln2p-like cytoplasmic localization pattern partially alters the functional specificity of Cln3p toward that of Cln2p. These results suggest that there are CLN-dependent cytoplasmic and nuclear events important for cell cycle initiation. This is the first indication of a cytoplasmic function for a cyclin-dependent kinase. The data presented here support the idea that cyclin function is regulated at the level of subcellular localization and that subcellular localization contributes to the functional specificity of Cln2p and Cln3p.

High-risk sexual behavior in Los Angeles: who receives testing for HIV?

No recent population-based data on HIV testing in people with high-risk sexual behavior are available. We sought predictors of testing using data from the 1997 Los Angeles County Health Survey, a random-digit telephone survey of 8004 county households. An estimated 2.3 million (35.5%) adults were tested for HIV in the past 2 years and approximately 370,000 (5.6%) engaged in high-risk sexual behavior (defined as having > or =2 partners in the past 12 months and not always using condoms). Among high-risk persons, an estimated 46% of heterosexual men, 56% of heterosexual women, and 72% of men who had sex with men (MSM) were tested for HIV. In a multivariable model of high-risk people, both heterosexual men (odds ratio [OR], 0.31; 95% confidence interval [CI], 0.16-0.61) and women (OR, 0.41; 95% CI, 0.19-0.87) had significantly lower proportions of testing than MSM. Although African Americans and Hispanics had significantly higher testing proportions than whites overall among all county residents, those reporting high-risk sexual behavior did not test at higher proportions. We conclude that the proportion of adults with high-risk sexual behavior tested for HIV is higher than almost a decade ago. However, testing among this group remains suboptimal. Future public health campaigns should intensify efforts to encourage HIV testing among this population.

The effect of weight loss intervention on antihypertensive medication requirements in the hypertension Optimal Treatment (HOT) study

Obesity is a significant risk factor for hypertension and the cardiovascular sequelae of hypertension. Weight loss has been shown to be effective in lowering blood pressure in overweight individuals. The purpose of this study was to show the impact of a weight loss intervention on overall medication requirements for obese, hypertensive patients. This was a substudy of the Hypertension Optimal Treatment (HOT) study. HOT study patients who had a body mass index > or =27 kg/m2 were randomized to receive either the weight loss intervention, which included dietary counseling and group support, or to serve as the control group. Patients' weights and number of medication steps (per HOT protocol) required to achieve target diastolic blood pressure were measured at 3, 6, 12, 18, 24, and 30 months. Patients in the weight loss group lost significantly more weight than the control group only at 6 months (-3.2+/-4.3 v. -1.8+/-2.7 kg [mean +/- SD] for weight loss group versus control, respectively, P = .05). The weight loss group tended to regain weight after the first 6 months of the study. However, patients in the weight loss group used a significantly fewer number of medication steps than the control group at all time intervals except 3 months. Weight loss appears to be a useful tool in blood pressure management in patients who require medication to control their blood pressure.

Relationship of Developmental Stage of Cantaloupe Fruit to Black Rot Susceptibility and Enzyme Production by Didymella bryoniae

Black rot of cantaloupe fruit, caused by Didymella bryoniae, can be severe when environmental conditions and fruit developmental stages are favorable for infection. Symptoms of black rot on cantaloupe fruit varied greatly depending on fruit age. The black rot phase was observed only on mature fruit. Inoculation of cantaloupe fruit at different developmental stages with five D. bryoniae isolates resulted in the greatest amount of decay on 10-day-old fruit compared with 20-, 30-, 40-, or 50-day-old fruit. There was no difference in lesion size among 20-, 30-, 40-, or 50-day-old fruit, although there was variation in lesion size among fungal isolates. Five fungal isolates all produced the greatest polygalacturonase (PG) activity in inoculated 10-day-old fruit compared with 20-, 30-, 40- or 50-day-old fruit. There was a positive correlation between lesion size and total fungal PG activity in decayed tissue. Using a representative D. bryoniae isolate (OK 963096), multiple PG isozymes were detected in both fungal shake culture and decayed fruit. Eleven PG isozymes (pI 4.7 to 7.9) were detected from fungal shake culture using pectin or polygalacturonic acid as the sole carbon source. Twelve PG isozymes (pI 4.7 to 8.7) were detected from decayed tissue of 10-day-old fruit, and 13 PG isozymes (pI 4.2 to 8.7) were observed from decayed tissue of 50-day-old fruit. The activity of D. bryoniae PG produced in vitro and in vivo was optimum at pH 5.0 and 5.5, respectively. The activity of the fungal PG produced in vitro exhibited primarily an endo-mode of action. In contrast, PG extracted from decayed tissue was predominately exo-PG. Thus, PG may play an important role in pathogenesis of D. bryoniae during cantaloupe fruit decay.

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.