ethan long - Profile on Academia.edu (original) (raw)

Papers by ethan long

Response-class hierarchies and resurgence of severe problem behavior

The Psychological Record, 2004

Journal of Applied Behavior Analysis, 2004

Behavior-reduction interventions typically employ dense schedules of alternative reinforcement in... more Behavior-reduction interventions typically employ dense schedules of alternative reinforcement in conjunction with operant extinction for problem behavior. After problem behavior is reduced in the initial treatment stages, schedule thinning is routinely conducted to make the intervention more practical in natural environments. In the current investigation, two methods for thinning alternative reinforcement schedules were compared for 3 clients who exhibited severe problem behavior. In the dense-to-lean (DTL) condition, reinforcement was delivered on relatively dense schedules (using noncontingent reinforcement for 1 participant and functional communication training for 2 participants), followed by systematic schedule thinning to progressively leaner schedules. During the fixed lean (FL) condition, reinforcement was delivered on lean schedules (equivalent to the terminal schedule of the DTL condition). The FL condition produced a quicker attainment of individual treatment goals for 2 of the 3 participants. The results are discussed in terms of the potential utility of using relatively lean schedules at treatment outset. DESCRIPTORS: extinction, schedule thinning, functional communication training, noncontingent reinforcement, response-prevention hypothesis We thank SungWoo Kahng, Karena Rush, and Geri Ruffin for their assistance.

Current issues regarding school-based functional assessment

The Behavior Analyst Today, 2000

Ge concentrations in pile-up layers of sub-100-nm SiGe films for nano-structuring by thermal oxidation

Journal of Vacuum Science & Technology B: Microelectronics and Nanometer Structures, 2012

ABSTRACT Export Date: 8 February 2013, Source: Scopus, Art. No.: 041212

The Psychological Record, 2014

We repeatedly paired preferred stimuli with known establishing properties and poster boards (i.e.... more We repeatedly paired preferred stimuli with known establishing properties and poster boards (i.e., neutral stimuli) to examine whether these poster boards would acquire the effects of a conditioned establishing operation in five children with autism. Following pairing, the poster boards, which had been previously shown to be neutral, increased immediate or subsequent engagement in stereotypy for 3 of 5 participants. The results suggest that it is possible to condition establishing operations for stereotypy and that this process may occur inadvertently. We discuss the potential clinical implications of the results as well as the need for future research to replicate our findings.

Research in Developmental Disabilities, 2005

The current study describes the use of noncontingent competing stimuli in the treatment of proble... more The current study describes the use of noncontingent competing stimuli in the treatment of problem behavior exhibited by three individuals during staff-assisted hygiene routines. Functional analyses revealed that particular topographies of problem behaviors appeared to be maintained by their own sensory consequences, whereas other topographies appeared to be maintained by escape from demands. Competing stimulus assessments were then conducted to identify items associated with low levels of automatically-maintained problem behavior and high levels of stimulus engagement. Stimuli associated with low levels of automatically-maintained problem behavior (competing stimuli) were then delivered noncontingently during staff-assisted hygiene routines that were problematic for each participant. In all three cases, substantial reductions in all problem behaviors were observed. These results are discussed in terms of the relative ease of this intervention and possible mechanisms underlying the effects of competing stimuli on behaviors maintained by different types of reinforcement.

physica status solidi (a), 2012

Despite the fact that germanium played a significant role in the advent of modern electronics, si... more Despite the fact that germanium played a significant role in the advent of modern electronics, silicon-germanium alloys have not been used or studied nearly as extensively as silicon. However, a recent resurgence in industrial and research interest in silicon-germanium ensures that it will have an increasingly important role in nano-and opto-electronics. It is unavoidable that a sound understanding of the oxidation of silicon-germanium will be required as processes are developed for using the material in electronic applications. In fact, a profound appreciation for the oxidation kinetics of silicon-germanium could itself create new applications for the material. The present work investigates the use of thermal oxidation in nanostructuring of epitaxially grown silicon-germanium by examining the kinetics of oxidation and the redistribution of germanium at the oxidation interface. This is done for oxidations in dry O 2 ambients with a particular focus on the influence of temperature and crystalline orientation on the post-oxidation germanium distribution. Physical characterization by x-ray diffraction and variable angle spectroscopic ellipsometry is used along with diffusion and oxidation modeling to derive a series of relations to describe the germanium content and layer thicknesses for the multiple layers created by oxidation. Both modeling and experimental results reveal that the germanium content at the oxidation front is strongly dependent on the oxidation temperature and only weakly dependent on the germanium content in the as-grown silicon-germanium layer. Evidence is presented showing that a decrease, rather than an increase, in the germanium content at the oxidation front may be achieved under certain conditions. The germanium content at the oxidation interface is used to discuss the potential for germanium to act as a catalyst or inhibitor for oxidation of silicon-germanium alloys. Taken together, germanium redistribution by thermal oxidation and the empiric relations presented here may be used to design process recipes for fabrication of nanostructures for nano-and opto-electronic applications.

Journal of Applied Physics, 2012

Several fundamental aspects of the oxidation-induced redistribution of Ge in thin films of SiGe a... more Several fundamental aspects of the oxidation-induced redistribution of Ge in thin films of SiGe are studied. This includes the incorporation of Ge into the oxide and the formation of what is alternatively referred to as pileup , snow-plow, or a germanium-rich layer. Experimental data from the present work shows longer oxidation times leading to an increase of Ge content in the pileup region and eventually creating a single high Ge content pileup layer by entirely consuming the initial SiGe layer. The pileup effect was shown to occur at the oxidation interface, with the highest Ge content occurring at the same interface. For a given oxide thickness, the redistribution of Ge and the formation of a pileup region was shown experimentally to be independent of temperature in the range between 800 C and 1000 C. Simulations using common models for the oxidation of Si and diffusion of Si in SiGe indicate that temperature does have an influence on the composition of the pileup layer, though the range of achievable compositions is limited. The flux of Si due to diffusion of Si in SiGe relative to the oxidation-induced flux of Si out of the SiGe is integral to the formation and dimensions of a pileup region. Two predictive relations were derived for describing the dynamics of oxidation of SiGe. The first relation is given for determining the pileup layer thickness as a function of oxide thickness and the composition of the pileup layer. The second relation assumes a limited supply of Si and is for determination of the minimum initial thickness of a SiGe layer to avoid oxidation of Ge. The validity of these equations was confirmed experimentally by RBS and XPS data from the present work. The proposed models may be used in nanostructuring of thin films of SiGe by oxidation and in the design of core-shell structures and transistors. This is all done with a focus on oxidation of epitaxial thin films (< 100 nm) of Si 1-X Ge X in dry O 2 at 1 atm between 800 C and 1000 C. V

Journal of Applied Physics, 2013

The present study examines the kinetics of dry thermal oxidation of (111), (110), and (100) silic... more The present study examines the kinetics of dry thermal oxidation of (111), (110), and (100) silicon-germanium (SiGe) thin epitaxial films and the redistribution of Ge near the oxidation interface with the aim of facilitating construction of single and multi-layered nano-structures. By employing a series of multiple and single step oxidations, it is shown that the paramount parameter controlling the Ge content at the oxidation interface is the oxidation temperature. The oxidation temperature may be set such that the Ge content at the oxidation interface is increased, kept static, or decreased. The Ge content at the oxidation interface is modeled by considering the balance between Si diffusion in SiGe and the flux of Si into the oxide by formation of SiO 2. The diffusivity of Si in SiGe under oxidation is determined for the three principal crystal orientations by combining the proposed empirical model with data from X-ray diffraction and variable angle spectroscopic ellipsometry. The orientation dependence of the oxidation rate of SiGe was found to follow the order: ð111Þ > ð110Þ > ð100Þ. The role of crystal orientation, Ge content, and other factors in the oxidation kinetics of SiGe versus Si are analyzed and discussed in terms of relative oxidation rates. V

Journal of Applied Behavior Analysis, 2002

This study evaluated a variation of functional assessment methodology, the structured descriptive... more This study evaluated a variation of functional assessment methodology, the structured descriptive assessment (SDA). The SDA is conducted in an individual's natural environment and involves systematically manipulating antecedent variables while leaving consequences free to vary. Results were evaluated by comparing the results of an SDA with results obtained from an analogue functional analysis with 4 children who exhibited problem behavior. For 3 of 4 participants, the results of the two assessments suggested similar hypotheses about variables maintaining problem behavior. Interventions based on the results of the SDA were implemented for 3 children and resulted in significant reductions in rates of problem behavior. DESCRIPTORS: functional assessment, functional analysis, intervention, problem behavior Research has demonstrated the utility of the analogue functional analysis methodology developed by Iwata, Dorsey, Slifer, Bauman, and Richman (1982/1994) for identifying sources of reinforcement that maintain aberrant behavior. This methodology systematically assesses situations hypothesized to be analogueous to those in the natural environment by directly manipulating putative antecedents and consequences for problem behavior. The major advantage of this methodology compared to other methods of functional assessment is that it allows greater control over the environment, resulting in a more direct inference of functional relations. In contrast to the analogue functional analysis, descriptive assessments involve direct observation of behavior and events in the individual's natural environment and in

Journal of Applied Behavior Analysis, 2008

Journal of Applied Behavior Analysis, 2001

Most preference assessments require individuals to choose among two or more stimuli. More recentl... more Most preference assessments require individuals to choose among two or more stimuli. More recently, the duration of engagement with items has been used as an index of preference. In the current study, the predictive validity of a single stimulus engagement (SSE) preference assessment was evaluated with 4 individuals. Stimuli were presented singly for a brief period while engagement with that stimulus was recorded. Although SSE preference rankings closely matched paired stimulus preference assessment rankings for only 2 of the 4 participants, relative preference rankings based on duration of engagement predicted relative reinforcer effectiveness for all participants in a subsequent concurrent-schedule reinforcer assessment. The SSE procedure took less time to administer than the paired stimulus procedure but produced less stable preference rankings across administrations. The SSE procedure may be appropriate for individuals who have difficulty selecting one stimulus from among two or more stimuli, and it may be well suited for evaluating activities that are difficult to present in a paired stimulus format.

Journal of Applied Behavior Analysis, 2005

Functional communication training (FCT) is a widely used treatment for individuals with developme... more Functional communication training (FCT) is a widely used treatment for individuals with developmental disabilities who exhibit severe behavior problems. One inherent challenge of employing FCT as a treatment in the community is that reinforcement for appropriate communication cannot always be immediate or even possible in some circumstances. Of the few studies that have incorporated some form of schedule thinning for communication, most have reported disruption of communication or increases in problem behavior when the schedule of reinforcement is thinned. In the current study, we compared FCT with extinction to FCT with extinction and access to competing stimuli. After conducting a functional analysis, a competing stimulus assessment was performed to identify stimuli that produce reinforcement that ostensibly competes with reinforcement that maintains problem behavior. It was hypothesized that FCT with competing stimuli would result in more stable reductions in problem behavior during schedule thinning, which would ultimately result in quicker achievement of the treatment goal (low levels of problem behavior under the terminal reinforcement schedule for communication) than FCT without competing stimuli. Results confirmed this hypothesis. DESCRIPTORS: functional communication training, competing stimuli, extinction, reinforcement schedule thinning We thank Iser DeLeon for his helpful comments during the preparation of this manuscript and Geri Ruffin, Rich Goysovich, and Art Wilke for their assistance with this study. Requests for reprints should be directed to Louis Hagopian,

Preference Assessment Procedures for Individuals with Developmental Disabilities

Behavior Modification, 2004

Significant advancements have been made in the development of procedures to systematically identi... more Significant advancements have been made in the development of procedures to systematically identify preferred stimuli that may function as reinforcers for persons with developmental disabilities. Indirect assessment procedures include care provider and client interviews, whereas direct assessment procedures involve systematically exposing participants to stimuli while recording their responses. These types of direct assessment procedures can be categorized as either approach-based or engagement-based. Approach-based procedures involve recording the individuals’ approach responses to stimuli presented singly or concurrently with other stimuli, whereas engagement-based procedures involve recording duration of engagement with stimuli. Although the predictive validity of indirect preference assessment procedures has yet to be established, using them in combination with direct measures of preferencemaybe most efficacious for identifying potential reinforcers. Recent research on preferenc...

Detection of temperature sensitive defects using ZTC

This work attempts to improve the common understanding of multiple temperature testing by present... more This work attempts to improve the common understanding of multiple temperature testing by presenting previously unpublished data as well as deriving a simple model for bounding an IC's performance within the three dimensional space defined by VDD, frequency, and ...

Evaluation of a Sexual Abuse Prevention Program for Female Chinese Adolescents With Mild Mental Retardation

American Journal on Mental Retardation, 1998

Programs to teach sexual abuse prevention skills to persons with mental retardation have rarely b... more Programs to teach sexual abuse prevention skills to persons with mental retardation have rarely been evaluated empirically, and typical evaluations are limited to assessment of the participants&amp;#39; knowledge rather than their performance of specific skills. In the present study, 6 adult women with mental retardation were trained in sexual abuse prevention, and performance was assessed using four separate measures: pretests and posttests of knowledge, verbal report, role play, and naturalistic probes. All women learned the skills but failed to exhibit them to criterion during the probes. We discuss the implications for further training and assessment of sexual abuse prevention skills.