Showing papers by "University of Nebraska Omaha published in 2003"

Three-Dimensional Tibiofemoral Kinematics of the Anterior Cruciate Ligament-Deficient and Reconstructed Knee during Walking

Abstract: BackgroundIt is possible that gait abnormalities may play a role in the pathogenesis of meniscal or chondral injury as well as osteoarthritis of the knee in patients with anterior cruciate ligament deficiency.HypothesisThe three-dimensional kinematics of anterior cruciate ligament-deficient knees are changed even during low-stress activities, such as walking, but can be restored by reconstruction.Study DesignCase control study.MethodsUsing a three-dimensional optoelectronic gait analysis system, we examined 13 patients with anterior cruciate ligament-deficient knees, 21 patients with anterior cruciate ligament-reconstructed knees, and 10 control subjects with uninjured knees during walking.ResultsNormal patterns of knee flexion-extension, abduction-adduction, and internal-external rotation during the gait cycle were maintained by all subjects. A significant difference in tibial rotation angle during the initial swing phase was found in anterior cruciate ligament-deficient knees compared with reconstructed...

Endocrine-disrupting effects of cattle feedlot effluent on an aquatic sentinel species, the fathead minnow.

Abstract: Over the last decade, research has examined the endocrine-disrupting action of various environmental pollutants, including hormones, pharmaceuticals, and surfactants, in sewage treatment plant effluent. Responding to the growth of concentrated animal feeding operations (CAFOs) and the pollutants present in their wastewater (e.g., nutrients, pharmaceuticals, and hormones), the U.S. Environmental Protection Agency developed a new rule that tightens the regulation of CAFOs. In this study, we collected wild fathead minnows (Pimephales promelas) exposed to feedlot effluent (FLE) and observed significant alterations in their reproductive biology. Male fish were demasculinized (having lower testicular testosterone synthesis, altered head morphometrics, and smaller testis size). Defeminization of females, as evidenced by a decreased estrogen:androgen ratio of in vitro steroid hormone synthesis, was also documented. We did not observe characteristics in either male or female fish indicative of exposure to environmental estrogens. Using cells transfected with the human androgen receptor, we detected potent androgenic responses from the FLE. Taken together, our morphologic, endocrinologic, and in vitro gene activation assay data suggest two hypotheses: a) there are potent androgenic substance(s) in the FLE, and/or b) there is a complex mixture of androgenic and estrogenic substances that alter the hypothalamic-pituitary-gonadal axis, inhibiting the release of gonadotropin-releasing hormone or gonadotropins. This is the first study demonstrating that the endocrine and reproductive systems of wild fish can be adversely affected by FLE. Future studies are needed to further investigate the effects of agricultural runoff and to identify the biologically active agents, whether natural or pharmaceutical in origin.

Opportunistic Mycelial Fungal Infections in Organ Transplant Recipients: Emerging Importance of Non-Aspergillus Mycelial Fungi

Abstract: To determine the spectrum and impact of mycelial fungal infections, particularly those due to non-Aspergillus molds, 53 liver and heart transplant recipients with invasive mycelial infections were prospectively identified in a multicenter study. Invasive mycelial infections were due to Aspergillus species in 69.8% of patients, to non-Aspergillus hyalohyphomycetes in 9.4%, to phaeohyphomycetes in 9.4%, to zygomycetes in 5.7%, and to other causes in 5.7%. Infections due to mycelial fungi other than Aspergillus species were significantly more likely to be associated with disseminated (P=.005) and central nervous system (P=.07) infection than were those due to Aspergillus species. Overall mortality at 90 days was 54.7%. The associated mortality rate was 100% for zygomycosis, 80% for non-Aspergillus hyalohyphomycosis, 54% for aspergillosis, and 20% for phaeohyphomycosis. Thus, non-Aspergillus molds have emerged as significant pathogens in organ transplant recipients. These molds are more likely to be associated with disseminated infections and to be associated with poorer outcomes than is aspergillosis.

The effects of anterior cruciate ligament reconstruction on tibial rotation during pivoting after descending stairs

Abstract: Recent in vitro research suggests that ACL reconstruction does not restore tibial rotation. This study investigated rotational knee joint stability in vivo during a combined descending and pivoting movement that applies a high rotational load to the knee joint. We studied 20 ACL reconstructed patients (bone–patellar tendon–bone graft) and 15 matched controls with a six-camera optoelectronic system performing the examined movement. In the control group the results showed no significant differences in the amount of tibial rotation between the two sides. No significant differences were also found between the contralateral intact leg of the ACL group and the healthy control. However, a significant difference was found within the ACL reconstructed group and between the reconstructed and the contralateral intact leg. Therefore ACL reconstruction may not restore tibial rotation even though anterior tibial translation has been reestablished.

Right ventricular outflow versus apical pacing in pacemaker patients with congestive heart failure and atrial fibrillation.

Abstract: Introduction: Prior studies suggest that right ventricular apical (RVA) pacing has deleterious effects. Whether the right ventricular outflow tract (RVOT) is a more optimal site for permanent pacing in patients with congestive heart failure (CHF) has not been established. Methods and Results: We conducted a randomized, cross-over trial to determine whether quality of life (QOL) is better after 3 months of RVOT than RVA pacing in 103 pacemaker recipients with CHF, left ventricular (LV) systolic dysfunction (LV ejection fraction ≤ 40%), and chronic atrial fibrillation (AF). An additional aim was to compare dual-site (RVOT + RVA, 31-ms delay) with single-site RVA and RVOT pacing. QRS duration was shorter during RVOT (167 ± 45 ms) and dual-site (149 ± 19 ms) than RVA pacing (180 ± 58 ms, P < 0.0001). At 6 months, the RVOT group had higher (P = 0.01) role-emotional QOL subscale scores than the RVA group. At 9 months, there were no significant differences in QOL scores between RVOT and RVA groups. Comparing RVOT to RVA pacing within the same patient, mental health subscale scores were better (P = 0.03) during RVOT pacing. After 9 months of follow-up, LVEF was higher (P = 0.04) in those assigned to RVA rather than RVOT pacing between months 6 and 9. After 3 months of dual-site RV pacing, physical functioning was worse (P = 0.04) than during RVA pacing, mental health was worse (P = 0.02) than during RVOT pacing, and New York Heart Association (NYHA) functional class was slightly better (P = 0.03) than during RVOT pacing. There were no other significant differences between RVA, RVOT and dual-site RV pacing in QOL scores, NYHA class, distance walked in 6 minutes, LV ejection fraction, or mitral regurgitation. Conclusion: In patients with CHF, LV dysfunction, and chronic AF, RVOT and dual-site RV pacing shorten QRS duration but after 3 months do not consistently improve QOL or other clinical outcomes compared with RVA pacing. (J Cardiovasc Electrophysiol, Vol. 14, pp. 1180-1186, November 2003)

Trends in risk profiles for and mortality associated with invasive aspergillosis among liver transplant recipients.

Abstract: To discern whether the characteristics and outcome of invasive aspergillosis in liver transplant recipients have evolved during the past decade, 26 patients who underwent transplantation during 1990–1995 (known as “the earlier cohort”) were compared with 20 patients who underwent transplantation during 1998–2001 (known as “the later cohort”) Twenty-three percent of the Aspergillus infections in the earlier cohort occurred 90 days after transplantation, compared with 55% of such infections in the later cohort (Pp026) The earlier cohort was significantly more likely to have disseminated infection (Pp034) and central nervous system (CNS) involvement (Pp0004) than was the later cohort The mortality rate was significantly higher for the earlier cohort(92%) than for the later cohort (60%; Pp012) Only disseminated infection (not the year of transplantation) approached statistical significance as an independent predictor of outcome In the current era, invasive aspergillosis occurs later in the posttransplantation period, is less likely to be associated with CNS infection, and is associated with a lower mortality rate, compared with invasive aspergillosis in the early 1990s

Cost effectiveness of peginterferon α-2b plus ribavirin versus interferon α-2b plus ribavirin for initial treatment of chronic hepatitis C

Abstract: Background: Peginterferon α-2b plus ribavirin therapy in previously untreated patients with chronic hepatitis C yields the highest sustained virological response rates of any treatment strategy but is expensive. Aims: To estimate the cost effectiveness of treatment with peginterferon α-2b plus ribavirin compared with interferon α-2b plus ribavirin for initial treatment of patients with chronic hepatitis C. Methods: Individual patient level data from a randomised clinical trial with peginterferon plus ribavirin were applied to a previously published and validated Markov model to project lifelong clinical outcomes. Quality of life and economic estimates were based on German patient data. We used a societal perspective and applied a 3% annual discount rate. Results: Compared with no antiviral therapy, peginterferon plus fixed or weight based dosing of ribavirin increased life expectancy by 4.2 and 4.7 years, respectively. Compared with standard interferon α-2b plus ribavirin, peginterferon plus fixed or weight based dosing of ribavirin increased life expectancy by 0.5 and by 1.0 years with incremental cost effectiveness ratios of €11 800 and €6600 per quality adjusted life year (QALY), respectively. Subgroup analyses by genotype, viral load, sex, and histology showed that peginterferon plus weight based ribavirin remained cost effective compared with other well accepted medical treatments. Conclusions: Peginterferon α-2b plus ribavirin should reduce the incidence of liver complications, prolong life, improve quality of life, and be cost effective for the initial treatment of chronic hepatitis C.

Finding cycles in synchronous Boolean networks with applications to biochemical systems

Abstract: This paper is an analytical study of Boolean networks. The motivation is our desire to understand the large, complicated and interconnected pathways which comprise intracellular biochemical signal transduction networks. The simplest possible conceptual model that mimics signal transduction with sigmoidal kinetics is the n-node Boolean network each of whose elements or nodes has the value 0 (off) or 1 (on) at any given time T = 0, 1, 2, …. A Boolean network has 2n states all of which are either on periodic cycles (including fixed points) or transients leading to cycles. Thus one understands a Boolean network by determining the number and length of its cycles. The problem one must circumvent is the large number of states (2n) since the networks we are interested in have 100 or more elements. Thus we concentrate on developing size n methods rather than the impossible task of enumerating all 2n states. This is done as follows: the dynamics of the network can be described by n polynomial equations which describe the logical function which determines the interaction at each node. Iterating the equations one step at a time finds all fixed points, period two cycles, period three cycles, etc. This is a general method that can be used to determine the fixed points and moderately large periodic cycles of any size network, but it is not useful in finding the largest cycles in a large network. However, we also show that the network equations can often be reduced to scalar form, which makes the cycle structure much more transparent. The scalar equations method is a true "size n" method and several examples (including nontrivial biochemical systems) are examined.

Bone mass, size, and density in children and adolescents with osteogenesis imperfecta: effect of intravenous pamidronate therapy.

Abstract: Cyclical intravenous therapy with pamidronate improves the clinical course in children and adolescents with osteogenesis imperfecta (OI). In this study, we evaluated the effect of this therapy on lumbar spine bone mass (bone mineral content [BMC]), size (bone volume [BV]), and density (volumetric bone mineral density [vBMD]). Results from 56 patients (age, 0.2-15.9 years; 25 girls) on long-term pamidronate treatment were compared with those of 167 patients who had not received pamidronate before densitometry. In all patients who received pamidronate, BMC, BV, and vBMD increased above levels expected for untreated patients (p < 0.001 in each case). After 4 years of treatment, BMC, BV, and vBMD were 154%, 44%, and 65% higher, respectively, in treated than in untreated patients who were matched for age and OI type. A multiple regression model showed that baseline BMC was negatively associated with the increase in BMC. In conclusion, the bone mass increase in pediatric OI patients receiving pamidronate is caused by increases in both bone size and density. Patients with larger deficits in bone mass at baseline have a more marked bone mass gain during therapy.

Burkitt's and Burkitt-like lymphoma in children and adolescents: a review of the Children's Cancer Group experience.

Abstract: Historically, the survival of children and adolescents with Burkitt's and Burkitt-like lymphoma had been poor. Recently, short and intensive chemotherapy appears to have improved disease outcome. We therefore reviewed the results of four successive Children's Cancer Group trials conducted on 470 children with disseminated Burkitt's and Burkitt-like lymphoma. Of the patients studied, the median age was 8 years (0-21 years), the male:female ratio was 4:1, 58% had lactate dehydrogenase (LDH) > or = 500 IU/l, 23% had M2 or M3 bone marrow (BM), and 12% demonstrated central nervous system involvement. In a multivariate analysis, the 4-year event-free survival (EFS) in patients > or = 15-years-old compared with or = 500 IU/l compared with LDH < 500 IU/l was 49 +/- 3 versus 71 +/- 4% (P < 0.001). Furthermore, patients treated on the most recent protocol, which was short and more intensive, had a significantly improved survival compared with those on previous trials (4-year EFS 80 +/- 6 versus 54 +/- 2%, P < 0.001). In summary, the outcome for childhood Burkitt's and Burkitt-like lymphoma has recently improved with the use of short and intensive B-cell non-Hodgkin's lymphoma-directed therapy.

Maps and the internet.

Abstract: Part 1 Introduction and contemporary issues: maps and the Internet - an introduction, M. Peterson geographic information literacy and the World Wide Web, J. Krygier, D. Peoples maps on the Web, W. Cartwright dissemination of census and other statistical data through Web maps, C.P.J.M. van Elzakker, F. Ormeling et al Internet cartography and official tourism destination Web sites, E.R. Richmond, C.P. Keller The Internet, cartographic surveillance, and locational privacy, M. Monmonier. Part 2 Technical development: developing cartographic applets for the Internet, A. Herzog GIS for everyone - the common GIS project and beyond, G. Andrienko, N. Andrienko, H. Voss beyond serving maps - serving GIS functionality over the Internet, Bin Jiang peer-to-peer sharing of cartographic data and software, Bin Li online cartography with XML, I. Zaslavsky Webmapping with scalable vector graphics, (SVG) - delivering the promise of high quality and interactive web maps, A. Neumann, A.M. Winter. A standards-based architecture for multi-purpose publishing of geodata on the web, L. Lehto an intelligent software agent architecture for distributed cartographic knowledge bases and Internet mapping services, Ming-Hsiang Tsou three-dimensional visualisation on the Internet, P. Ottoson supporting wayfinding in desktop geovirtual environments, S. Fuhrmann. Part 3 Applications and user issues: mapping and internet based public transportation journey planning and information systems, P. Mooney, A.C. Winstanley from maps to student interaction - creating a Web-based student atlas of Russia, J.S. Torguson, M.M. Blinnikov historical geoinformation on the Web - lessons learned from the chapter 91 pilot project, A. Giordano Web-based multimedia GIS - exploring interactive maps and associated multimedia information on the internet, S. Hu Internet, maps and public participation - contemporary limits and possibilities, S. Caquard Cartography, virtual reality, and the internet - integrating abstract models of the environment via the internet, R.G. Cammack QuickTime virtual reality maps for the Web, W. Schwertley telecartography - maps, multimedia and the mobile Internet, G. Gartner geodata communication on personal digital assistants, PDA), T. Wintges. Part 4 Theoretical development: the concept of cybercartography, D.R. Fraser Taylor modelling the visualization of Internet maps, L. Brodersen foundations of research in Internet cartography, M. Peterson.

Information Systems Success

Abstract: is Research Coordinator at the Center for the Management ofInformation at the University of Arizona and Associate Professor of CollaborationEngineering at Delft University of Technology in the Netherlands. He is also Directorof Research and Development for GroupSystems.com. As a reseiu-cher, he has pub-lished more than 60 scholarly works on the theoretical foundations collaboration,and he applies his findings to the development and deployment of collaborative tech-nology to enhance team productivity, team creativity, and team satisfaction. His workon organizational transition to collaborative technology led to new insights abouthow to conceive of and deploy group support systems so as to create self-sustainingand growing communities of users. He received his Ph.D. from University of Arizonain 1994.

The Effect of the Private Securities Litigation Reform Act of 1995 on Accounting Discretion of Client Managers of Big 6 and Non‐Big 6 Auditors

Abstract: This study examines how the Private Securities Litigation Reform Act of 1995 (PSLRA) affects auditors' incentives to curtail earnings management by client managers. The most significant reform of PSLRA was the elimination of joint and several liability under which auditors and other parties could be named to lawsuits because of ‘deep pockets’ rather than culpability. While the elimination of joint and several liability provides significant relief to auditors from litigation, opponents of PSLRA argue that it discourages meritorious lawsuits and lowers audit quality, reducing investor confidence in markets. The potential benefit would be greatest for Big 6 firms, who have the highest exposure (largest clients) and significant resources to pay damages. In this paper we argue that if PSLRA induces decreases in audit quality, then we should expect increases in the prevalence of accruals after this Act. To investigate this issue we examine the discretionary accruals of a sample of 2,600 companies three years be...

Managerial ownership and firm valuation

Abstract: We study the relation between managerial ownership and Tobin's q ( Q ) for 123 Japanese firms from 1987 to 1995. Managers in Japanese firms own a smaller stake in their firms relative to their US counterparts. Our initial analyses using an Ordinary Least Squares (OLS) regression model show a negative (positive) relation between Q and managerial ownership at low (high) levels of ownership. However, we argue that this finding is most likely a statistical artifact. When we control for firm fixed effects, suggested by recent literature, we reach a different conclusion. Specifically, we find that Q increases monotonically with managerial ownership. Our findings, therefore, suggest that as ownership increases, there is a greater alignment of managerial interests with those of stockholders. This conclusion remains when both managerial ownership and Q are treated as endogenous variables in a simultaneous equation system.

The effects of stereotyped toys and gender on play assessment in children aged 18-47 months

Abstract: The goals of the present study were to identify the impact particular stereotyped toys have on young children's complexity of play; to identify how these behaviours may influence children's cognitive development using play assessment; and to ascertain the toys that would be most appropriate for use in play assessment sessions. A total of 30 children who ranged in age from 18-47 months were observed playing for 30 minutes in a playroom. Analyses revealed that higher levels of play complexity were only manifested when children played with female stereotyped toys. The implications for practitioners of this and other findings are discussed.

Multiple criteria linear programming approach to data mining: Models, algorithm designs and software development

Abstract: It is well known that data mining has been implemented by statistical regressions, induction decision tree, neural networks, rough set, fuzzy set and etc. This paper promotes a multiple criteria linear programming (MCLP) approach to data mining based on linear discriminant analysis. This paper first describes the fundamental connections between MCLP and data mining, including several general models of MCLP approaches. Given the general models, it focuses on a designing architecture of MCLP-data mining algorithms in terms of a process of real-life business intelligence. This architecture consists of finding MCLP solutions, preparing mining scores, and interpreting the knowledge patterns. Secondly, this paper elaborates the software development of the MCLP-data mining algorithms. Based on a pseudo coding, two versions of software (SAS- and Linux-platform) will be discussed. Finally, the software performance analysis over business and experimental databases is reported to show its mining and prediction power. As a part of the performance analysis, a series of data testing comparisons between the MCLP and induction decision tree approaches are demonstrated. These findings suggest that the MCLP-data mining techniques have a great potential in discovering knowledge patterns from a large-scale real-life database or data warehouse.

Tracking superparamagnetic iron oxide labeled monocytes in brain by high-field magnetic resonance imaging

Abstract: Inflammatory cells, most notably mononuclear phagocytes (MP; macrophages and microglia), play a critical role in brain homeostasis, repair and disease. One important event in cellular biodynamics is how MP move in and throughout the nervous system. Prior studies have focused principally on cell migration across the blood-brain barrier during neuroinflammatory processes with little work done on cell movement within the brain. During the past decade our laboratories have studied the role of MP in HIV-1-associated dementia (HAD). In HAD MP incite sustained glial inflammatory reactions causing significant neuronal damage. To extend these works we investigated cell movement in brain and its influence for disease in a novel co-registration system integrating neuropathology with high-field magnetic resonance imaging (MRI). Human monocytes labeled with superparamagnetic iron oxide particles were injected into the brain of severe combined immunodeficient (SCID) mice. MRI was recorded 1, 7, and 14 days after cell injection. MRI co-registered with histology verified that the MRI signal modification was due to the labeled cells. MRI showed human monocyte-derived macrophages along the injection site, the corpus callosum, the ventricular system and in other brain sites. These data support the idea that cell migration can be monitored in vivo and provides an opportunity to assess monocyte mobility in brain and its affects on neurodegenerative processes and notably HAD.

Who gets caught at maturity gap? A study of pseudomature, immature, and mature adolescents:

Abstract: This research examined links among adolescents' maturity status, their biological, social, and psychological characteristics, and parents' perceptions of their adolescents' maturity The participants were 430 Canadian adolescents in the sixth and ninth grades, and a subsample of their parents Pattern-centred analyses confirmed the existence of three clusters of adolescents differing in maturity status: pseudomature (25%), immature (30%), and mature (44%) Further analyses found differences among the clusters in adolescents' pubertal status, the social context (presence of older siblings and friends), and their desired age, involvement in pop culture, school and peer involvement, and close friendships Analysis of mother and father reports revealed some differences in how parents of pseudomature, immature, and mature adolescents perceived their adolescents' maturity, and in how they felt about their adolescents' maturity There were few grade differences in the findings The results suggest that pseudomat

Evaluation of Reinforcement Learning Control for Thermal Energy Storage Systems

Abstract: This paper describes a simulation-based investigation of machine-learning control for the supervisory control of building energy systems. Model-free reinforcement learning control is investigated for the operation of electrically driven cool thermal energy storage systems in commercial buildings. The reinforcement learning controller learns to charge and discharge a thermal storage tank based on the feedback it receives from past control actions. The learning agent interacts with its environment by commanding the thermal energy storage system and extracts cues about the environment solely based on the reinforcement feedback it receives, which in this study is the monetary cost of each control action. No prediction or system model is required. Over time and by exploring the environment, the reinforcement learning controller establishes a statistical summary of plant operation, which is continuously updated as operation continues. The controller learns to account for the time-dependent cost of electricity (...

Endurance training and performance in runners: research limitations and unanswered questions.

Abstract: The purpose of this review is to discuss several limitations common to research concerning running and, secondly, to identify selected areas where additional research appears needed. Hopefully, this review will provide guidance for future research in terms of topics, as well as design and methodology. Limitations in the research include: lack of longitudinal studies, inadequate description of training status of individuals, lack of confirmation of state of rest, nourishment and hydration, infrequent use of allometric scaling to express oxygen uptake, relative neglect of anaerobic power and physical structure as determinants of performance, neglect of the central nervous system, and reliance on laboratory data. Further research in a number of areas is needed to enhance our knowledge of running performance. This includes: body mass as a performance determinant, evaluation of methods used to measure economy of running, assessing the link between strength and running performance, and further examination of training methods. While the amount of research on distance running is voluminous, the present state of knowledge is somewhat restricted by the limitations in research design and methodology identified here.

An extinct genus of Salicaceae based on twigs with attached flowers, fruits, and foliage from the Eocene Green River Formation of Utah and Colorado, USA.

Abstract: A newly recovered twig with attached leaves and flowers from the Eocene Green River Formation of Utah provides the basis for recognizing a new, extinct genus of Salicaceae sensu lato (s.l.). Pseudosalix handleyi gen. et sp. nov. has alternate lanceolate leaves with pinnate, semicraspedodromous venation and a serrate margin with glandular teeth. The inflorescence is terminal on the twig and is unisexual, composed of flowers organized in a paniculoid cyme, with lateral paraclades of pedicellate flowers. The attached pistillate flowers have four prominent sepals that are valvate in bud, spreading but basally fused at anthesis; the single pistil of each flower is ovoid with three or four longitudinal sutures, indicating development to a capsular fruit. Three or four recurved styles radiate from the apex of the pistil, each with a distal globose stigma. The infructescence, verified by attachment to twigs with the same kind of leaves, bore capsular fruits of three and four valves. Associated but unattached, staminate flowers also have four well-developed, basally connate sepals. They are pedicellate and bear several stamens, each with a short filament and globose anther. The available morphological characters place the fossil species within the Salicaceae s.l. as an immediate sister to the clade containing Populus and Salix. Although the likely outgroup genera (including Itoa, Poliothyrsis, Carrierea, and Idesia) to tribe Saliceae all occur in Asia today and not North America, the occurrence of both Pseudosalix and Populus in the Eocene of Utah raises the possibility of a North American origin for the Saliceae.

Social Change Affects Vocal Structure in a Callitrichid Primate (Callithrix kuhlii)

Abstract: Vocal plasticity in the face of changing social context is well-documented in passerine birds, but the degree to which changes in social environment affect the vocal structure of non-human primates is a topic which has remainedlargely unexplored. We assessed whether modification of social environments, in this case the presence of marmosets in neighboring cages, influencedthe vocal morphology of phee calls, which possess signature-like features, in Wied’s black tufted-ear marmosets (Callithrix kuhlii). Individual phee calls were obtained over a period of 8 wk from 11 animals maintainedin rooms with stable social environments. After this baseline phase, seven marmosets were housed for an additional 8 wk in rooms that containedcages with unfamiliar marmosets, while four marmosets maintained the same neighbors as the first phase. Calls were digitized and both frequency and temporal parameters were measured. Multivariate discriminant function analyses (DFA) generatedfrom vocalizations collectedin the first phase producedfunctions that accurately classified calls to the correct individual, showing that calls had significant individual distinctiveness. DFAs generated from vocalizations in the first phase of the study continued to show high classification accuracy for marmosets in a stable social environment, but DFAs from the first phase were significantly less likely to correctly classify vocalizations in marmosets that were housednext to novel conspecifics. These data show that phee calls, which have signature-like properties in marmosets, can be modified by changes in social context. The results suggest a degree of plasticity in vocal signals that is rare among non-human primates.

Adolescents' Characteristics and Parents' Beliefs as Predictors of Parentsapos; Peer Management Behaviors

Abstract: This study examined parents’ reported use of peer management behaviors (i.e., communicating preferences, communicating disapproval, supporting friendships, and information seeking) and linked these behaviors to (a) adolescents’ self-reported psychosocial adjustment and friendships and (b) parents’ beliefs about adolescents’ peer relationships (i.e., perceived efficacy in managing adolescents’ friendships and concerns about adolescents’ friendships). The participants were 269 parents (161 mothers, 108 fathers) and their predominantly White adolescents in Grades 6 and 9 (N = 177). Results suggest that parents may be more apt to use some behaviors (e.g., communicating disapproval and information seeking) when there are indications that their adolescents are engaged in problem behaviors and have friends who are deviant. In addition, parents’ concerns about their adolescents’ friends mediate the relationship between adolescent problem behaviors and parents’ communications of disapproval. Parents’ peer management is promising as a route to understand further the nature of parent-peer linkages.