Showing papers by "Kent State University published in 2009"

A benchmark study on the thermal conductivity of nanofluids

Abstract: This article reports on the International Nanofluid Property Benchmark Exercise, or INPBE, in which the thermal conductivity of identical samples of colloidally stable dispersions of nanoparticles or “nanofluids,” was measured by over 30 organizations worldwide, using a variety of experimental approaches, including the transient hot wire method, steady-state methods, and optical methods. The nanofluids tested in the exercise were comprised of aqueous and nonaqueous basefluids, metal and metal oxide particles, near-spherical and elongated particles, at low and high particle concentrations. The data analysis reveals that the data from most organizations lie within a relatively narrow band (±10% or less) about the sample average with only few outliers. The thermal conductivity of the nanofluids was found to increase with particle concentration and aspect ratio, as expected from classical theory. There are (small) systematic differences in the absolute values of the nanofluid thermal conductivity among the various experimental approaches; however, such differences tend to disappear when the data are normalized to the measured thermal conductivity of the basefluid. The effective medium theory developed for dispersed particles by Maxwell in 1881 and recently generalized by Nan et al. [J. Appl. Phys. 81, 6692 (1997)], was found to be in good agreement with the experimental data, suggesting that no anomalous enhancement of thermal conductivity was achieved in the nanofluids tested in this exercise.

Systematic measurements of identified particle spectra in pp, d+Au, and Au+Au collisions at the star detector.

Abstract: Identified charged-particle spectra of pi(+/-), K(+/-), p, and (p) over bar at midrapidity (vertical bar y vertical bar < 0.1) measured by the dE/dx method in the STAR (solenoidal tracker at the BNL Relativistic Heavy Ion Collider) time projection chamber are reported for pp and d + Au collisions at root s(NN) = 200 GeV and for Au + Au collisions at 62.4, 130, and 200 GeV. Average transverse momenta, total particle production, particle yield ratios, strangeness, and baryon production rates are investigated as a function of the collision system and centrality. The transverse momentum spectra are found to be flatter for heavy particles than for light particles in all collision systems; the effect is more prominent for more central collisions. The extracted average transverse momentum of each particle species follows a trend determined by the total charged-particle multiplicity density. The Bjorken energy density estimate is at least several GeV/fm(3) for a formation time less than 1 fm/c. A significantly larger net-baryon density and a stronger increase of the net-baryon density with centrality are found in Au + Au collisions at 62.4 GeV than at the two higher energies. Antibaryon production relative to total particle multiplicity is found to be constant over centrality, but increases with the collision energy. Strangeness production relative to total particle multiplicity is similar at the three measured RHIC energies. Relative strangeness production increases quickly with centrality in peripheral Au + Au collisions, to a value about 50% above the pp value, and remains rather constant in more central collisions. Bulk freeze-out properties are extracted from thermal equilibrium model and hydrodynamics-motivated blast-wave model fits to the data. Resonance decays are found to have little effect on the extracted kinetic freeze-out parameters because of the transverse momentum range of our measurements. The extracted chemical freeze-out temperature is constant, independent of collision system or centrality; its value is close to the predicted phase-transition temperature, suggesting that chemical freeze-out happens in the vicinity of hadronization and the chemical freeze-out temperature is universal despite the vastly different initial conditions in the collision systems. The extracted kinetic freeze-out temperature, while similar to the chemical freeze-out temperature in pp, d + Au, and peripheral Au + Au collisions, drops significantly with centrality in Au + Au collisions, whereas the extracted transverse radial flow velocity increases rapidly with centrality. There appears to be a prolonged period of particle elastic scatterings from chemical to kinetic freeze-out in central Au + Au collisions. The bulk properties extracted at chemical and kinetic freeze-out are observed to evolve smoothly over the measured energy range, collision systems, and collision centralities.

Loneliness as the cause and the effect of problematic Internet use: the relationship between Internet use and psychological well-being.

Abstract: The current research started from the assumption that one of the major motives driving individuals' Internet use is to relieve psychosocial problems (e.g., loneliness, depression). This study showed that individuals who were lonely or did not have good social skills could develop strong compulsive Internet use behaviors resulting in negative life outcomes (e.g., harming other significant activities such as work, school, or significant relationships) instead of relieving their original problems. Such augmented negative outcomes were expected to isolate individuals from healthy social activities and lead them into more loneliness. Even though previous research suggests that social use of the Internet (e.g., social networking sites, instant messaging) could be more problematic than entertainment use (e.g., downloading files), the current study showed that the former did not show stronger associations than the latter in the key paths leading to compulsive Internet use.

Ardipithecus ramidus and the Paleobiology of Early Hominids

Abstract: Hominid fossils predating the emergence of Australopithecus have been sparse and fragmentary. The evolution of our lineage after the last common ancestor we shared with chimpanzees has therefore remained unclear. Ardipithecus ramidus, recovered in ecologically and temporally resolved contexts in Ethiopia's Afar Rift, now illuminates earlier hominid paleobiology and aspects of extant African ape evolution. More than 110 specimens recovered from 4.4-million-year-old sediments include a partial skeleton with much of the skull, hands, feet, limbs, and pelvis. This hominid combined arboreal palmigrade clambering and careful climbing with a form of terrestrial bipedality more primitive than that of Australopithecus. Ar. ramidus had a reduced canine/premolar complex and a little-derived cranial morphology and consumed a predominantly C3 plant-based diet (plants using the C3 photosynthetic pathway). Its ecological habitat appears to have been largely woodland-focused. Ar. ramidus lacks any characters typical of suspension, vertical climbing, or knuckle-walking. Ar. ramidus indicates that despite the genetic similarities of living humans and chimpanzees, the ancestor we last shared probably differed substantially from any extant African ape. Hominids and extant African apes have each become highly specialized through very different evolutionary pathways. This evidence also illuminates the origins of orthogrady, bipedality, ecology, diet, and social behavior in earliest Hominidae and helps to define the basal hominid adaptation, thereby accentuating the derived nature of Australopithecus.

Social comparison as a predictor of body dissatisfaction: A meta-analytic review.

Abstract: The relationship between social comparison and body dissatisfaction was examined using meta-analysis. Several demographic and methodological variables were examined as potential moderators. Data from 156 studies (189 effect sizes) showed that social comparison was related to higher levels of body dissatisfaction. The effect for social comparison and body dissatisfaction was stronger for women than men and inversely related to age. This effect was stronger when social comparison was directly measured rather than inferred. No differences emerged for the presence of eating psychopathology, study design, or object of comparison. Results confirm theory and research suggesting that comparing oneself unfavorably to another on the basis of appearance may lead to dissatisfaction with one's own appearance. Moderator variables refine our understanding of the social comparison-body dissatisfaction relationship. These constructs and their relationship should be explored further in future studies.

Azimuthal charged-particle correlations and possible local strong parity violation

Abstract: Parity-odd domains, corresponding to nontrivial topological solutions of the QCD vacuum, might be created during relativistic heavy-ion collisions. These domains are predicted to lead to charge separation of quarks along the system's orbital momentum axis. We investigate a three-particle azimuthal correlator which is a P even observable, but directly sensitive to the charge separation effect. We report measurements of charged hadrons near center-of-mass rapidity with this observable in Au+Au and Cu+Cu collisions at s(NN)=200 GeV using the STAR detector. A signal consistent with several expectations from the theory is detected. We discuss possible contributions from other effects that are not related to parity violation.

A Constructivist Approach to Online Learning: The Community of Inquiry Framework

Abstract: This chapter presents a theoretical model of online learning, the Community of Inquiry (CoI) framework, which is grounded in John Dewey’s progressive understanding of education. The CoI framework is a process model of online learning which views the online educational experience as arising from the interaction of three presences – social presence, cognitive presence, and teaching presence. Each of these three elements in the CoI model are described and related to Dewey’s work, and research findings and issues concerning them reviewed. The development of a common CoI survey measure that promises to address some of these issues is described and discussed. The chapter concludes with emerging findings from new studies which use the CoI survey, directions for future research, and practical uses of the CoI model.

Does Self-Reported Posttraumatic Growth Reflect Genuine Positive Change?

Abstract: In this study, we evaluated the validity of self-reported posttraumatic growth (PTG) by assessing the relation between perceived growth and actual growth from pre- to posttrauma. Undergraduate students completed measures tapping typical PTG domains at Time 1 and Time 2 (2 months later). We compared change in those measures with scores on the Posttraumatic Growth Inventory (PTGI; Tedeschi & Calhoun, 1996) for those participants who reported a traumatic event between Time 1 and Time 2 (n = 122). PTGI scores generally were unrelated to actual growth in PTG-related domains. Moreover, perceived growth was associated with increased distress from pre- to posttrauma, whereas actual growth was related to decreased distress, a pattern suggesting that perceived and actual growth reflect different processes. Finally, perceived (but not actual) growth was related to positive reinterpretation coping. Thus, the PTGI, and perhaps other retrospective measures, does not appear to measure actual pre- to posttrauma change.

Social Interaction and Co-Viewing With YouTube: Blending Mass Communication Reception and Social Connection

Abstract: This study examined whether motives and individual differences (social activity, interpersonal interaction, locus of control, sensation-seeking, innovativeness and YouTube affinity) predicted viewing videos on YouTube and sharing videos with others. Consistent with uses and gratifications assumptions, motives and individual differences differentially predicted viewing and sharing behaviors. Participants viewed videos for information seeking, and viewed and shared videos for entertainment, co-viewing and social interaction. Results suggest that while people watch videos on YouTube for some of the same reasons identified in studies of television viewing, there is a distinctly social aspect to YouTube use that reflects its social networking characteristics.

Screening for social anxiety disorder with the self-report version of the Liebowitz Social Anxiety Scale.

Abstract: Objective: This study examined whether the self-report version of the Liebowitz Social Anxiety Scale (LSAS-SR) could accurately identify individuals with social anxiety disorder and individuals with the generalized subtype of social anxiety disorder. Furthermore, the study sought to determine the optimal cutoffs for the LSAS-SR for identifying patients with social anxiety disorder and its generalized subtype. Methods: Two hundred and ninety-one patients with clinician-assessed social anxiety disorder (240 with generalized social anxiety disorder) and 53 control participants who were free from current Axis-1 disorders completed the LSAS-SR. Results: Receiver Operating Characteristic analyses revealed that the LSAS-SR performed well in identifying participants with social anxiety disorder and generalized social anxiety disorder. Consistent with Mennin et al.’s [2002: J Anxiety Disord 16:661–673] research on the clinician-administered version of the LSAS, cutoffs of 30 and 60 on the LSAS-SR provided the best balance of sensitivity and specificity for classifying participants with social anxiety and generalized social anxiety disorder, respectively. Conclusions: The LSAS-SR may be an accurate and cost-effective way to identify and subtype patients with social anxiety disorder, which could help increase the percentage of people who receive appropriate treatment for this debilitating disorder. Depression and Anxiety 26:34–38, 2009. & 2008 Wiley-Liss, Inc.

Reexamining Human Origins in Light of Ardipithecus ramidus

Abstract: Referential models based on extant African apes have dominated reconstructions of early human evolution since Darwin’s time. These models visualize fundamental human behaviors as intensifications of behaviors observed in living chimpanzees and/or gorillas (for instance, upright feeding, male dominance displays, tool use, culture, hunting, and warfare). Ardipithecus essentially falsifies such models, because extant apes are highly derived relative to our last common ancestors. Moreover, uniquely derived hominid characters, especially those of locomotion and canine reduction, appear to have emerged shortly after the hominid/chimpanzee divergence. Hence, Ardipithecus provides a new window through which to view our clade’s earliest evolution and its ecological context. Early hominids and extant apes are remarkably divergent in many cardinal characters. We can no longer rely on homologies with African apes for accounts of our origins and must turn instead to general evolutionary theory. A proposed adaptive suite for the emergence of Ardipithecus from the last common ancestor that we shared with chimpanzees accounts for these principal ape/human differences, as well as the marked demographic success and cognitive efflorescence of later Plio-Pleistocene hominids.

Assessment of Bias Associated with Incomplete Extraction of Microbial DNA from Soil

Abstract: DNA extraction bias is a frequently cited but poorly understood limitation of molecular characterizations of environmental microbial communities. To assess the bias of a commonly used soil DNA extraction kit, we varied the cell lysis protocol and conducted multiple extractions on subsamples of clay, sand, and organic soils. DNA, as well as bacterial and fungal ribosomal gene copies as measured by quantitative PCR, continued to be isolated in successive extractions. When terminal restriction fragment length polymorphism was used, a significant shift in community composition due to extraction bias was detected for bacteria but not for fungi. Pyrosequencing indicated that the relative abundances of sequences from rarely cultivated groups such as Acidobacteria, Gemmatimonades, and Verrucomicrobia were higher in the first extraction than in the sixth but that the reverse was true for Proteobacteria and Actinobacteria. This suggests that the well-known phylum-level bacterial cultivation bias may be partially exaggerated by DNA extraction bias. We conclude that bias can be adequately reduced in many situations by pooling three successive extractions, and additional measures should be considered when divergent soil types are compared or when comprehensive community analysis is necessary.

The Great Divides: Ardipithecus ramidus Reveals the Postcrania of Our Last Common Ancestors with African Apes

Abstract: Genomic comparisons have established the chimpanzee and bonobo as our closest living relatives. However, the intricacies of gene regulation and expression caution against the use of these extant apes in deducing the anatomical structure of the last common ancestor that we shared with them. Evidence for this structure must therefore be sought from the fossil record. Until now, that record has provided few relevant data because available fossils were too recent or too incomplete. Evidence from Ardipithecus ramidus now suggests that the last common ancestor lacked the hand, foot, pelvic, vertebral, and limb structures and proportions specialized for suspension, vertical climbing, and knuckle-walking among extant African apes. If this hypothesis is correct, each extant African ape genus must have independently acquired these specializations from more generalized ancestors who still practiced careful arboreal climbing and bridging. African apes and hominids acquired advanced orthogrady in parallel. Hominoid spinal invagination is an embryogenetic mechanism that reoriented the shoulder girdle more laterally. It was unaccompanied by substantial lumbar spine abbreviation, an adaptation restricted to vertical climbing and/or suspension. The specialized locomotor anatomies and behaviors of chimpanzees and gorillas therefore constitute poor models for the origin and evolution of human bipedality.

The Pelvis and Femur of Ardipithecus ramidus: The Emergence of Upright Walking

Abstract: The femur and pelvis of Ardipithecus ramidus have characters indicative of both upright bipedal walking and movement in trees. Consequently, bipedality in Ar. ramidus was more primitive than in later Australopithecus. Compared with monkeys and Early Miocene apes such as Proconsul, the ilium in Ar. ramidus is mediolaterally expanded, and its sacroiliac joint is located more posteriorly. These changes are shared with some Middle and Late Miocene apes as well as with African apes and later hominids. However, in contrast to extant apes, bipedality in Ar. ramidus was facilitated by craniocaudal shortening of the ilium and enhanced lordotic recurvature of the lower spine. Given the predominant absence of derived traits in other skeletal regions of Ar. ramidus, including the forelimb, these adaptations were probably acquired shortly after divergence from our last common ancestor with chimpanzees. They therefore bear little or no functional relationship to the highly derived suspension, vertical climbing, knuckle-walking, and facultative bipedality of extant African apes.

Traumatic Events Among Undergraduate Students: Prevalence and Associated Symptoms

Abstract: This multisite study assessed the prevalence of exposure to traumatic events and associated symptoms among undergraduate students (N = 1,528) using online surveys. Most students (85%) reported having experienced a traumatic event in their lifetime (Time 1) and 21% reported experiencing an event over a 2-month period during college (Time 2). The most common event reported at both time points was the unexpected death of a loved one. Lifetime exposures to family violence, unwanted sexual attention, and sexual assault were associated with higher current distress levels. When nominated as a worst event, sexual assault was associated with the most posttraumatic stress disorder symptoms. Events that caused intense fear, helplessness, or horror and those that were intentionally caused were associated with higher distress levels. Total number of lifetime traumas consistently had the highest associations with distress levels. Implications for counseling psychology practice, training, and research are discussed.

Combining prehension and propulsion: the foot of Ardipithecus ramidus.

Abstract: Several elements of the Ardipithecus ramidus foot are preserved, primarily in the ARA-VP-6/500 partial skeleton. The foot has a widely abducent hallux, which was not propulsive during terrestrial bipedality. However, it lacks the highly derived tarsometatarsal laxity and inversion in extant African apes that provide maximum conformity to substrates during vertical climbing. Instead, it exhibits primitive characters that maintain plantar rigidity from foot-flat through toe-off, reminiscent of some Miocene apes and Old World monkeys. Moreover, the action of the fibularis longus muscle was more like its homolog in Old World monkeys than in African apes. Phalangeal lengths were most similar to those of Gorilla. The Ardipithecus gait pattern would thus have been unique among known primates. The last common ancestor of hominids and chimpanzees was therefore a careful climber that retained adaptations to above-branch plantigrady.

Long range rapidity correlations and jet production in high energy nuclear collisions

Abstract: The STAR Collaboration at the Relativistic Heavy Ion Collider presents a systematic study of high-transverse-momentum charged-di-hadron correlations at small azimuthal pair separation Delta phi in d+Au and central Au+Au collisions at s(NN)=200 GeV. Significant correlated yield for pairs with large longitudinal separation Delta eta is observed in central Au+Au collisions, in contrast to d+Au collisions. The associated yield distribution in Delta eta x Delta phi can be decomposed into a narrow jet-like peak at small angular separation which has a similar shape to that found in d+Au collisions, and a component that is narrow in Delta phi and depends only weakly on Delta eta, the "ridge." Using two systematically independent determinations of the background normalization and shape, finite ridge yield is found to persist for trigger p(t)>6 GeV/c, indicating that it is correlated with jet production. The transverse-momentum spectrum of hadrons comprising the ridge is found to be similar to that of bulk particle production in the measured range (2 < p(t)< 4 GeV/c).

Careful Climbing in the Miocene: The Forelimbs of Ardipithecus ramidus and Humans Are Primitive

Abstract: The Ardipithecus ramidus hand and wrist exhibit none of the derived mechanisms that restrict motion in extant great apes and are reminiscent of those of Miocene apes, such as Proconsul. The capitate head is more palmar than in all other known hominoids, permitting extreme midcarpal dorsiflexion. Ar. ramidus and all later hominids lack the carpometacarpal articular and ligamentous specializations of extant apes. Manual proportions are unlike those of any extant ape. Metacarpals 2 through 5 are relatively short, lacking any morphological traits associable with knuckle-walking. Humeral and ulnar characters are primitive and like those of later hominids. The Ar. ramidus forelimb complex implies palmigrady during bridging and careful climbing and exhibits none of the adaptations to vertical climbing, forelimb suspension, and knuckle-walking that are seen in extant African apes.

3-HOP: a high-compression indexing scheme for reachability query

Abstract: Reachability queries on large directed graphs have attracted much attention recently. The existing work either uses spanning structures, such as chains or trees, to compress the complete transitive closure, or utilizes the 2-hop strategy to describe the reachability. Almost all of these approaches work well for very sparse graphs. However, the challenging problem is that as the ratio of the number of edges to the number of vertices increases, the size of the compressed transitive closure grows very large. In this paper, we propose a new 3-hop indexing scheme for directed graphs with higher density. The basic idea of 3-hop indexing is to use chain structures in combination with hops to minimize the number of structures that must be indexed. Technically, our goal is to find a 3-hop scheme over dense DAGs (directed acyclic graphs) with minimum index size. We develop an efficient algorithm to discover a transitive closure contour, which yields near optimal index size. Empirical studies show that our 3-hop scheme has much smaller index size than state-of-the-art reachability query schemes such as 2-hop and path-tree when DAGs are not very sparse, while our query time is close to path-tree, which is considered to be one of the best reachability query schemes.

Reading Fluency: More than Automaticity? More than a Concern for the Primary Grades?.

Abstract: Reading fluency has traditionally been viewed as a goal of reading that is taught and mastered in the elementary grades. In this article we challenge that notion by exploring the role of reading fluency as a contributor to reading proficiency and difficulty among intermediate and middle grade students. We assessed reading fluency development among a large number of third-, fifth-, and seventh-grade students, using prosody (expressiveness in oral reading) rather than reading rate (word recognition automaticity) as a measure of reading fluency. We found moderately strong correlations between fluency and silent reading comprehension as measured by a standardized achievement test at all three grade levels. Our findings suggest that reading fluency appears to be a significant variable in upper elementary and middle grade students' reading. Moreover, the findings add to mounting evidence that prosody is an important component in the full manifestation of reading fluency. Both components of fluency, automaticity...

Agenda-based regulation of study-time allocation: When agendas override item-based monitoring.

Abstract: Theories of self-regulated study assume that learners monitor item difficulty when making decisions about which items to select for study. To complement such theories, the authors propose an agenda-based regulation (ABR) model in which learners' study decisions are guided by an agenda that learners develop to prioritize items for study, given their goals and task constraints. Across 4 experiments, the authors orthogonally manipulated 1 task constraint-the reward structure of the task-with objective item difficulty, so that learners could use either item difficulty or potential reward in deciding how to allocate their study time. Learners studied items, were tested, and then selected half the items for restudy. As predicted by the ABR model, reward structure drove item selection more than did item difficulty, which demonstrates learners' agendas can override the effects of monitoring item difficulty in the allocation of study time.

Determining Evidence-Based Practices in Special Education

Abstract: Determining evidence-based practices is a complicated enterprise that requires analyzing the methodological quality and magnitude of the available research supporting specific practices. This article reviews criteria and procedures for identifying what works in the fields of clinical psychology, school psychology, and general education; and it compares these systems with proposed guidelines for determining evidence-based practices in special education. The authors then summarize and analyze the approaches and findings of the 5 reviews presented in this issue. In these reviews, prominent special education scholars applied the proposed quality indicators for high-quality research and standards for evidence-based practice to bodies of empirical literature. The article concludes by synthesizing these scholars' preliminary recommendations for refining the proposed quality indicators and standards for evidence-based practices in special education, as well as the process for applying them.

Trajectories of Resilience, Resistance, and Distress During Ongoing Terrorism: The Case of Jews and Arabs in Israel

Abstract: This is the 1st longitudinal examination of trajectories of resilience and resistance (rather than ill-being) among a national sample under ongoing threat of mass casualty. The authors interviewed a nationally representative sample of Jews and Arabs in Israel (N = 709) at 2 times during a period of terrorist and rocket attacks (2004-2005). The resistance trajectory, exhibiting few or no symptoms of traumatic stress and depression at both time points, was substantially less common (22.1%) than has previously been documented in studies following single mass casualty events. The resilience trajectory, exhibiting initial symptoms and becoming relatively nonsymptomatic, was evidenced by 13.5% of interviewees. The chronic distress trajectory was documented among a majority of participants (54.0%), and a small proportion of persons were initially relatively symptom-free but became distressed (termed delayed distress trajectory; 10.3%). Less psychosocial resource loss and majority status (Jewish) were the most consistent predictors of resistance and resilience trajectories, followed by greater socioeconomic status, greater support from friends, and less report of posttraumatic growth.

Paleobiological implications of the Ardipithecus ramidus dentition.

Abstract: The Middle Awash Ardipithecus ramidus sample comprises over 145 teeth, including associated maxillary and mandibular sets. These help reveal the earliest stages of human evolution. Ar. ramidus lacks the postcanine megadontia of Australopithecus. Its molars have thinner enamel and are functionally less durable than those of Australopithecus but lack the derived Pan pattern of thin occlusal enamel associated with ripe-fruit frugivory. The Ar. ramidus dental morphology and wear pattern are consistent with a partially terrestrial, omnivorous/frugivorous niche. Analyses show that the ARA-VP-6/500 skeleton is female and that Ar. ramidus was nearly monomorphic in canine size and shape. The canine/lower third premolar complex indicates a reduction of canine size and honing capacity early in hominid evolution, possibly driven by selection targeted on the male upper canine.

Energy spectra of cosmic-ray nuclei at high energies

Abstract: We present new measurements of the energy spectra of cosmic-ray (CR) nuclei from the second flight of the balloon-borne experiment Cosmic-Ray Energetics And Mass (CREAM). The instrument included different particle detectors to provide redundant charge identification and measure the energy of CRs up to several hundred TeV. The measured individual energy spectra of C, O, Ne, Mg, Si, and Fe are presented up to ~1014 eV. The spectral shape looks nearly the same for these primary elements and it can be fitted to an E –2.66 ± 0.04 power law in energy. Moreover, a new measurement of the absolute intensity of nitrogen in the 100-800 GeV/n energy range with smaller errors than previous observations, clearly indicates a hardening of the spectrum at high energy. The relative abundance of N/O at the top of the atmosphere is measured to be 0.080 ± 0.025 (stat.)±0.025 (sys.) at ~800 GeV/n, in good agreement with a recent result from the first CREAM flight.

The costs of services and employment outcomes achieved by adults with autism in the US

Abstract: This article examines the cost of services and employment outcomes obtained by adults with autism within the United States vocational rehabilitation (VR) system. It found that the number of such individuals has increased by more than 121 percent from 2002 to 2006. Moreover, though adults with autism were employed at higher rates than most disability groups investigated, they tended to work far fewer hours and earn less in wages per week. The study also found that adults with autism were among the most costly individuals to serve.