Dissolved organic matter quantity and quality response of tropical rainforest headwater rivers to the transition from dry to wet season.

Dissolved organic matter (DOM) and its composition in aquatic ecosystems is a key indicator of ecosystem function and an important component of the global carbon cycle. Tropical rainforest headwaters play an important role in global carbon cycling. However, there is a large uncertainty on how DOM sources interact during mobilisation and the potential fate of associated carbon and nutrients. Using field techniques to measure dissolved organic carbon (DOC) concentration and composition, changes in DOM source from headwaters to larger downstream rivers were observed. This study shows that the hydrological connectivity, developed during the transition from dry to wet seasons, changes the DOM supply and transport across a tropical river catchment. The observed variability in the DOC-river discharge relationship provides further evidence of the changes in the DOM supply in a small headwater. This novel insight into the seasonal changes of the dynamics of DOM supply to the river helps understanding the mobilization of terrestrial DOM to tropical headwaters and its export from smaller to larger rivers. It also highlights the data gap in the study of smaller headwaters which may account for uncertainty in estimating the terrestrial carbon transported by inland waters.

Stability of implants and natural teeth as determined by the Periotest over 60 months of function.

Various methods for evaluating tooth mobility have been developed throughout the years, but their acceptance has been limited because of the subjectivity associated with their use. In recent years, the Periotest has been studied and used to evaluate the mobility of natural teeth and is claimed to b e potentially reliable in assessing the stability of the implant-bone interface. Few clinical implant studies have used natural teeth as controls to monitor changes in mobility associated with dental implants. The Dental Implant Clinical Research Group initiated a long-term clinical study in 1991 to assess the influence of design, application, and site of placement on clinical success and crestal bone height. As part of the study, Periotest values (PTVs) were recorded for 2,623 of the 2,998 implants placed and uncovered. For the statistical analysis, 2,623 implants were tested at second-stage surgery, with the number of implants tested varying at each follow-up visit. Data were collected from investigators at 32 study centers for periods ranging up to 60 months. A total of 975 natural teeth from 409 partially edentulous study subjects served as controls. FPVs on natural teeth and implants were combined, and the overall average Periotest values (OA-PTVs) were compared with values for individual subjects. The effect of implant and natural tooth locations on mobility were evaluated and compared with each other. The combined OA-PTV for all natural teeth was +1.8 and the OA-PTV for all implants was -3.4 PTVs. Compared with those in the maxillae, mandibular teeth and implants were found to be more stable Implants were found to be significantly more stable as compared with natural teeth. The recorded variations in PTVs for natural teeth and implants over the entire evaluation period were not found to be significantly different. This study developed the following conclusions: (1) implants were found to be significantly less mobile as compared with natural teeth for individual subjects; (2) the PTVs for natural teeth and implants did not exhibit significant variation over the evaluation period; (3) the Periotest can provide reproducible assessment of stability in a long-term clinical study; and (4) changes in PTVs may be helpful in evaluating improvement or degradation of the implant-bone complex.

The influence of bone thickness on facial marginal bone response: stage 1 placement through stage 2 uncovering.

BACKGROUND: Various causes of facial bone loss around dental implants are reported in the literature; however, reports on the influence of residual facial bone thickness on the facial bone response (loss or gain) have not been published. This study measured changes in vertical dimension of facial bone between implant insertion and uncovering and compared these changes to facial bone thickness for more than 3,000 hydroxyapatite (HA)-coated and non-HA-coated root-form dental implants. METHODS: Subjects were predominantly white males, 18 to 80+ years of age (mean 62.9 years), who were patients at 30 Department of Veterans Affairs Medical Centers and two university dental clinics. Alveolar ridges ranged from normal to resorbed with intact basal bone. Following preparation of the osteotomy site, direct measurements with calipers were made of the residual facial bone thickness, approximately 0.5 mm below the crest of the bone. The distance from the top of the implants to the crest of the facial bone was also measured using periodontal probes. Implants were uncovered between 3 to 4 months in the mandible and 6 to 8 months in the maxilla after insertion. Facial bone response was the difference between the height of facial bone at Stage 1 (insertion) and Stage 2 (uncovering). RESULTS: The mean facial bone thickness after osteotomies were made was 1.7 +/- 1.13 mm. When a mean facial bone thickness of 1.8 +/- 1.41 mm or larger remained after site preparation, bone apposition was more likely to occur. The mean facial bone response for 2,685 implants was -0.7 +/- 1.70 mm. For implants integrated at uncovering, the mean bone response was -0.7 +/- 1.69 mm, and -2.8 +/- 1.57 mm for implants mobile at uncovering. Bone quality-4 had the least facial bone response, -0.5 +/- 2.11 mm. Bone responses were similar for both HA-coated and non-HA-coated implants. CONCLUSIONS: Significantly greater amounts of facial bone loss were associated with implants that failed to integrate. As the bone thickness approached 1.8 to 2 mm, bone loss decreased significantly and some evidence of bone gain was seen. There was no statistically or clinically significant difference in bone response between HA-coated and non-HA-coated implants.

Periodontal-type measurements associated with hydroxyapatite-coated and non-HA-coated implants: uncovering to 36 months.

BACKGROUND: While the use of hydroxyapatite (HA)-coated endosseous dental implants has gained in popularity over the past 10 years, the short-term and long-term predictability and indications for their use remain highly controversial. Some reports suggest that the HA coating may separate from the substructure, undergo dissolution in tissue fluids, and/or contribute to rapid osseous breakdown around the implant. Other reports, however, relate favorable responses to HA-coated implants, which include rapid bone adaptation to the HA, greater stability at uncovering, and increased coronal bone growth. These contradictions may be related to differences in chemical composition of the HA on the implant surface. Most clinicians and researchers may agree that long-term, independent, scientific clinical studies are needed to compare HA-coated and non-HA-coated (titanium-alloy and CP-titanium) implants under the same conditions. Concerns appear in the literature that HA-coated implants experience greater breakdown because they are more susceptible to bacterial colonization due to their roughness and hydrophilicity. Some studies suggest that specific putative periodontal pathogens may adhere to the HA, thereby predisposing the implant to greater peri-implantitis than that experienced by non-HA implants. METHODS: A total of 32 clinical research centers, located in various geographic regions of the United States, were selected to participate in a comprehensive clinical study. More than 2,900 HA-coated and non-HA implants were randomized as to location within one of three jaw regions--maxillary anterior, mandibular anterior, and mandibular posterior--and followed for 36 months. It can be assumed that in each of these jaw regions, the conditions associated with both implant surface types would be similar enough to permit meaningful comparisons of periodontal-type measurements that have not previously been reported. Periodontal-type measurements (gingiva, plaque, suppuration, and calculus indices; probing depth; attachment levels; recession; and keratinized tissue width) for each aspect of each implant (mesial, facial, distal, and lingual) were recorded at 3, 6, 9, 12, 18, 24, and 36 months following implant uncovering. The implant was considered the experimental unit for analysis using generalized estimating equation and repeated measure methods. Data for the four aspects of each implant, as well as measurements over time, were all clustered in the unit of analysis. RESULTS: The percentages of implants with zeros recorded for the indices was remarkably similar for both HA-coated and non-HA implants. While statistically significant differences were found for some of the measurements associated with HA-coated and non-HA implants under certain conditions, these differences were too small to be considered clinically significant. CONCLUSIONS: Overall, there was no clinically significant difference between the periodontal-type measurements for HA-coated and non-HA-coated implants followed for a period from 3 through 36 months. The concerns about HA-coated implants being associated with adverse periodontal responses for the HA chemical composition included in this study appear to be unfounded for a period of clinical performance up to 36 months.

Revising the blueprint for the AOCN Examination using a role delineation study for advanced practice oncology nursing.

PURPOSE/OBJECTIVES: To conduct a role delineation study of advanced oncology nursing practice as a basis for the blueprint for the Advanced Oncology Certified Nurse (AOCN) Examination. DESIGN: Descriptive and comparative. SAMPLE: A group of 802 Oncology Nursing Society members comprised of 258 oncology nurse practitioners (NPs), 235 oncology clinical nurse specialists (CNSs), and 309 baccalaureate-prepared oncology nurses. METHODS: A pilot survey was mailed to a small group to allow refinement of the survey instrument. The survey then was mailed to a total sample of 2,400. MAIN RESEARCH VARIABLES: Frequency and importance to practice of 121 survey items as well as whether each item reflected an entry-level skill. Survey items were divided into five major domains: (a) Direct Caregiver, (b) Consultant, (c) Administrator/Coordinator, (d) Researcher and (e) Educator. FINDINGS: Direct Caregiver domain was weighted most heavily (63%), followed by Educator (18%), Consultant (10%), Administrator/Coordinator (5%), and Researcher (4%). Most of the items were identified as entry-level skills, and fewer than 10% of the items differentiated between CNS and NP respondents. CONCLUSION: The blueprint for the AOCN Examination reflects entry-level advanced practice oncology nursing and is appropriate for both CNSs and NPs in oncology. IMPLICATIONS FOR NURSING PRACTICE: Examinees, consumers, and employers can have confidence that the AOCN Examination will be based on a blueprint that was revised to reflect current oncology nursing practice and, therefore, is valid for its purpose.

Promoter studies in hemostasis.

In recent years the technique of gene cloning, coupled with the application of polymerase chain reaction (PCR)-based procedures, has greatly facilitated the production of cloned genomic material encompassing the putative promoter regions of genes involved in the hemostatic process. These recombinant vectors provide the raw material for reporter gene studies and DNA footprinting analysis; two of the three most frequently used in vitro procedures to study promoter function. The third of these methods to be described in this chapter, band shift or electrophoretic mobility shift assay (EMSA), normally uses synthetically produced double-stranded oligonucleotide sequences corresponding to specific areas of interest within the promoter region.

A study of the role of the generalist oncology nurse as a basis for revision of the blueprint for certification.

PURPOSE/OBJECTIVES: To delineate the current role of the generalist oncology nurse as a basis for revision of the blueprint for the OCN Exam. DESIGN: Survey of generalist oncology nurses. SAMPLE: 1,200 oncology nurses randomly chosen from the general membership of the Oncology Nursing Society who completed and returned surveys. METHODS: Surveys developed by subject matter experts and mailed by American College Testing. MAIN RESEARCH VARIABLES: Frequency and importance of 201 oncology nursing activities previously identified by a group of experts in oncology nursing. FINDINGS: Highest ranked items for combined frequency and importance pertained to comfort, information, protective mechanisms, and coping. Lowest ranked items pertained to prevention, detection, research, and sexuality. CONCLUSIONS: The blueprint was redesigned to include eight domains of practice: quality of life (27%), gastrointestinal and urinary function (15%), protective mechanisms (15%), scientific basis for practice (12%), cardiopulmonary function (10%), health promotion (8%), oncologic emergencies (7%), and professional performance (6%). IMPLICATIONS FOR NURSING PRACTICE: Because oncology nursing is changing, it is necessary to reconfirm and update the blueprint for the certification exam. Certification exams for the generalist nurse beginning in May 1996 were based on this updated blueprint.

The task difficulty of free throw shooting for males and females.

The study demonstrated how the binomial trials model could be used to enhance performance evaluation of a psychomotor task. The study was designed to accomplish three purposes: (a) calibrate the task difficulty of shooting free throws; (b) determine if free-throw shooting is a more difficult task for females than males; and (c) demonstrate how grading scales could be developed when a difference in task difficulty exists. Adults (202 males and 196 females) ranging in age from 18 to 55 years shot 17 consecutive free throws. The performance scores were analyzed using the binomial trials model. The model fit the data for the total group and the females. Because no males scored 0 or more than 13, the model did not fit the data at the extremes of the score continuum. The task difficulty for females was 0.793 (SE = 0.084) and 0.068 (SE = 0.081) for males, which indicated differential item functioning, Chi 1(2) = 38.73, p < .0001. Shooting free throws with a men's regulation basketball was a more difficult task for females than males, which indicates the task does not measure the same latent trait ability for both groups. On average the males' probability of making a free throw was .146 units higher than for the females. Ability estimates were mapped to observed scores for males and females separately and used to illustrate how fair grading scales could be developed.

Friction melt distribution in a multi-ring impact basin.

It is generally accepted that multi-ring basins are the consequence of very large impacts, but the mechanism by which they form is still a matter of contention. Most of what is currently known about multi-ring basins is based on remote studies of the Moon and, to a lesser extent, Mars and Mercury. But at least two multi-ring impact basins have been recognized on Earth--the Sudbury (Canada) and Vredefort (South Africa) impact structures--providing an opportunity to study their properties directly. Here we describe the distribution of friction melt (pseudotachylyte) in the floor of the Sudbury impact basin. Although the veins and dykes of pseudotachylyte decrease in both thickness and frequency of occurrence towards the basin periphery, the greatest volumes of friction melt appear to define four rings around the central impact melt sheet. Field evidence indicates that the rings originated as zones of large displacement, which facilitated localized frictional melting of the basin floor during the modification (collapse) stage of the cratering process. By analogy, we argue that the rings of other multi-ring impact basins are also likely to be the remnants of such large-displacement fault zones.

Advanced practice in oncology nursing: a role delineation study.

PURPOSE: To identify the elements that comprise the role of the advanced practice oncology nurse. DESIGN: Survey. SETTING: National. SAMPLE: 637 master's-prepared nurses in oncology clinical practice and 619 baccalaureate nurses who were in their first four years of certification as oncology nurses. METHODS: Using a 190-item survey composed of five subscales (Direct Caregiver, Consultant, Administrator/Coordinator, Researcher, and Educator) listing advanced practice behaviors, respondents were asked to indicate the frequency with which they performed each behavior and the importance of each behavior to their practice. MAIN RESEARCH VARIABLES: The elements of the advanced practice role differentiated from those elements of the role of the nurse who is practicing at the generalist level (i.e., non-master's-prepared). FINDINGS: The majority of items showed a significant difference between the the two groups with the greatest similarities in the area of Direct Caregiver and the greatest differences in the areas of Consultant and Researcher. Advanced practice nurses indicated that they performed the behaviors on the Direct Caregiver and Educator subscales most frequently and believed these behaviors to be most important to their practice. CONCLUSION: Significant differences exist between the roles of nurses in basic and advanced oncology nursing practice. IMPLICATIONS FOR NURSING PRACTICE: The results of the role delineation study have been used to design the blueprint for the Advanced Oncology Nursing Certification Test, to be administered for the first time in April 1995.

Physical and social impact of alpha 1-antitrypsin deficiency: results of a survey.

BACKGROUND: Emphysema associated with alpha 1-antitrypsin deficiency can impose serious impairment. OBJECTIVE: To gather information about the impact of severe alpha 1-antitrypsin deficiency. METHODS: Mail survey, descriptive statistics. RESULTS: We sent a survey to 1730 subscribers to a national newsletter, 850 of whom had previously stated they had alpha 1-antitrypsin deficiency. A total of 414 questionnaires were returned; 398 respondents said they had alpha 1-antitrypsin deficiency, and 300 said they had the PiZZ phenotype. Sixty-six respondents who said they had the disease did not know their phenotype. Among the 304 respondents with severe deficiency, the mean age at the time symptoms first appeared was 35.0 years, but the mean age when the disease was diagnosed was 41.3 years. Overall, 75.3% of respondents with severe deficiency reported at least one adverse effect: 44.4% retired early, and 19.1% changed to a physically easier job. The duration of diagnostic delay correlated with the degree of adverse psychosocial effects. CONCLUSIONS: Alpha 1-antitrypsin deficiency frequently escapes diagnosis despite many medical encounters. Affected individuals are often unaware of basic details of their disease. Many patients report adverse psychosocial effects. Delay in diagnosing this disease is associated with adverse psychosocial effects.

Effects of violating local independence on IRT parameter estimation for the Binomial Trials Model.

The appropriateness of the Binomial Trials Model for test data that consist of multiple attempts of the same item needs to be determined because the presence of learning or fatigue effects may violate the model's assumption of local independence. The purpose of this study was to determine what effect the severity of the violation of local independence (VLI), coupled with different sample size (SS), test length (TL), and test difficulty (TD) had on the estimation of the model difficulty parameter, b, using computer simulation techniques. Each of the following conditions was replicated 100 times under a completely crossed design: SS (100, 200, 500, 2,000); TL (5, 10, 20, 25 attempts); TD (-1.2, 0.0, 1.2); and VLI (from no violation to complete violation). Examinee ability or latent trait was pseudorandomly drawn from a standard normal distribution, and the b-parameter was estimated using a maximum likelihood procedure on generated test scores. Regardless of SS, TL, and TD, the b-parameter tended to be overestimated for situations in which the VLI condition simulated fatigue and underestimated when the VLI condition simulated late-test learning or practice effect. The findings suggest that violations of local independence, at least as simulated in this study, could seriously bias the difficulty parameter estimates if all examinees tested exhibited the dependency.

Time series analysis of knowledge of results effects during motor skill acquisition.

Time series analysis was used to investigate the hypothesis that during acquisition of a motor skill, knowledge of results (KR) information is used to generate a stable internal referent about which response errors are randomly distributed. Sixteen subjects completed 50 acquisition trials of each of three movements whose spatial-temporal characteristics differed. Acquisition trials were either blocked, with each movement being presented in series, or randomized, with the presentation of movements occurring in random order. Analysis of movement time data indicated the contextual interference effect reported in previous studies was replicated in the present experiment. Time series analysis of the acquisition trial data revealed the majority of individual subject response patterns during blocked trials were best described by a model with a temporarily stationary, internal reference of the criterion and systematic, trial-to-trial variation of response errors. During random trial conditions, response patterns were usually best described by a "White-noise" model. This model predicts a permanently stationary, internal reference associated with randomly distributed response errors that are unaffected by KR information. These results are not consistent with previous work using time series analysis to describe motor behavior (Spray & Newell, 1986).

One-parameter item response theory models for psychomotor tests involving repeated, independent attempts.

Three one-parameter item response theory models are given as viable models that describe the observed score probabilities of an examinee who takes a multiple attempts, single-item test of a psychomotor skill. These models include the Binomial Trials Model, the Poisson Counts Model, and the Inverse Binomial Model. The paper presents these models and offers suggestions for their estimation and subsequent use in the assessment of psychomotor behavior.

The effect of neuroleptics and tardive dyskinesia on smooth-pursuit eye movement in chronic schizophrenics.

We sought to determine whether such state-related factors as neuroleptic treatment and facio-oral tardive dyskinesia (TD) influence smooth-pursuit eye movement (SPEM) in chronic schizophrenics. The design involved 100 schizophrenics, 64 of whom showed "abnormal" eye tracking. Experimentally drug-withdrawn patients, some of whom were clinically relapsed, were compared with control patients who continued taking medication in prewithdrawal and postwithdrawal SPEM tests. All groups showed a slight worsening in eye-tracking performance on two postwithdrawal tests, but significant group-by-test session "interactions" were not demonstrable. We also determined that patients with TD tend to substitute large, nontracking saccades for SPEM to a significantly greater extent than nondyskinetic patients. Our findings strengthen the supposition that impaired SPEM is a trait in many schizophrenics but suggest that patients with TD be excluded in future studies of SPEM addressed to trait issues.

Absolute error revisited: an accuracy indicator in disguise.

When target accuracy is defined as the probability that an individual will respond to an accuracy task within a fixed distance around the target, then the composite error measures, E and AE, are shown to be fairly strong indicators of target accuracy in a relative sense. When AE and E are compared, AE is shown to be an even stronger accuracy indicator than E for most reasonable accuracy requirements. This, plus the fact that AE has certain desirable properties in ANOVA procedures, suggests that AE is a good, composite measure of target accuracy and should be analyzed first to determine if target accuracy differences exist. Subsequent analyses of bias and/or variability are then recommended.

Episodic and residual thought pathology in chronic schizophrenics: effect of neuroleptics.

We sought to determine the effect of neuroleptic treatment on thought disorder in chronic schizophrenics, using the Thought Disorder Index (TDI). We were able to demonstrate that high levels of thought disorder are found in chronic schizophrenic and schizoaffective patients, while in both bipolar patients and normal controls thought pathology is minimal. Moreover, the TDI appears to be particularly well suited to the characterization of thought disorder in chronic schizophrenics. For total scores on the TDI, we were unable to demonstrate a significant reduction in thought pathology, although it was evident that thought disorder as reflected in the Conceptual Disorganization and Unusual Thought Content subscales of the Brief Psychiatric Rating Scale is significantly reduced by neuroleptics. In analyses of subscores of the TDI reflecting four levels of severity, we were able to show that more severe forms of thought pathology are normalized by neuroleptics, while less severe pathology is largely unaffected. Our results suggest that neuroleptic treatment reduces thought pathology associated with acute episodes, but that somewhat milder, though still disabling, residual thought pathology persists after clinical remission has been attained.