Transmission risk of infectious droplets in physical spreading process at different times: A review.

Droplets provide a well-known transmission media in the COVID-19 epidemic, and the particle size is closely related to the classification of the transmission route. However, the term "aerosol" covers most particle sizes of suspended particulates because of information asymmetry in different disciplines, which may lead to misunderstandings in the selection of epidemic prevention and control strategies for the public. In this review, the time when these droplets are exhaled by a patient was taken as the initial time. Then, all available viral loads and numerical distribution of the exhaled droplets was analyzed, and the evaporation model of droplets in the air was combined with the deposition model of droplet nuclei in the respiratory tract. Lastly, the perspective that physical spread affects the transmission risk of different size droplets at different times was summarized for the first time. The results showed that although the distribution of exhaled droplets was dominated by small droplets, droplet volume was proportional to the third power of particle diameter, meaning that the viral load of a 100 µm droplet was approximately 106 times that of a 1 µm droplet at the initial time. Furthermore, the exhaled droplets are affected by heat and mass transfer of evaporation, water fraction, salt concentration, and acid-base balance (the water fraction > 98%), which lead them to change rapidly, and the viral survival condition also deteriorates dramatically. The time required for the initial diameter (do) of a droplet to shrink to the equilibrium diameter (de, about 30% of do) is approximately proportional to the second power of the particle diameter, taking only a few milliseconds for a 1 µm droplet but hundreds of milliseconds for a 10 µm droplet; in other words, the viruses carried by the large droplets can be preserved as much as possible. Finally, the infectious droplet nuclei maybe inhaled by the susceptible population through different and random contact routes, and the droplet nuclei with larger de decompose more easily into tiny particles on account of the accelerated collision in a complex airway, which can be deposited in the higher risk alveolar region. During disease transmission, the infectious droplet particle size varies widely, and the transmission risk varies significantly at different time nodes; therefore, the fuzzy term "aerosol" is not conducive to analyzing disease exposure risk. Recommendations for epidemic prevention and control strategies are: 1) Large droplets are the main conflict in disease transmission; thus, even if they are blocked by a homemade mask initially, it significantly contains the epidemic. 2) The early phase of contact, such as close-contact and short-range transmission, has the highest infection risk; therefore, social distancing can effectively keep the susceptible population from inhaling active viruses. 3) The risk of the fomite route depends on the time in contact with infectious viruses; thus, it is important to promote good health habits (including frequent hand washing, no-eye rubbing, coughing etiquette, normalization of surface cleaning), although blind and excessive disinfection measures are not advisable. 4) Compared with the large droplets, the small droplets have larger numbers but carry fewer viruses and are more prone to die through evaporation.

Evaluating the predictive validity of a single stimulus engagement preference assessment.

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.

A functional analysis of hair pulling.

We experimentally assessed the functions of hair pulling and hair manipulation of a 19-year-old woman (Kris) with moderate mental retardation and cerebral palsy. In Phase 1 a functional analysis revealed that Kris pulled and manipulated hair for the greatest amount of time in the alone condition, suggesting that the behaviors were maintained by some form of automatic reinforcement (Vaughan & Michael, 1982). In Phase 2 we assessed the nature of the sensory stimulation that maintained hair pulling by providing continuous access to previously pulled or cut hair and, thereafter, by having Kris wear a rubber glove. The results suggested that hair pulling was maintained by digital-tactile stimulation (automatic positive reinforcement). These findings are discussed, and recommendations for further analyses of automatically reinforced habit behaviors are provided.

Augmenting simplified habit reversal in the treatment of oral-digital habits exhibited by individuals with mental retardation.

We investigated whether a simplified habit reversal treatment eliminates fingernail biting and related oral-digital habits exhibited by individuals with mild to moderate mental retardation. Although simplified habit reversal did little to decrease the target behaviors for 3 of 4 participants, simplified habit reversal plus additional treatment procedures decreased the behavior to near-zero levels for all participants. These procedures included remote prompting, remote contingencies involving differential reinforcement plus response cost, and differential reinforcement of nail growth. Limitations of habit reversal for individuals with mental retardation along with directions for future research involving therapist-mediated treatment procedures, particularly those involving remote prompting and remote contingencies, are discussed.

Training and generalization of sexual abuse prevention skills for women with mental retardation.

Previous research has shown that behavioral skills training to teach sexual abuse prevention skills to women with mental retardation results in skill acquisition but poor generalization. In this investigation we evaluated procedures for enhancing generalization following training. Five women with mental retardation received 10 behavioral skills training sessions followed by in situ training when the skills did not fully generalize. Behavioral skills training resulted in skill acquisition and in situ training produced generalized responding during naturalistic assessments.

A review of behavioral and pharmacological treatments for habit disorders in individuals with mental retardation.

This paper reviews the prevalence and behavioral and pharmacological treatment-outcome studies for habit disorders exhibited by individuals with mental retardation. The treatment-outcome studies target the habit disorders identified previously by researchers including nervous habits (nail biting, bruxism, and trichotillomania), motor and vocal tics, and Tourette's disorder. The paucity of behavioral treatments and the lack of controlled pharmacological research warrants further experimental evaluation of treatments for habit disorders affecting individuals with mental retardation. Conclusions and recommendations for future research are made.

Simplified habit reversal treatment for chronic hair pulling in three adolescents: a clinical replication with direct observation.

Three developmentally normal adolescents with chronic hair pulling were treated with a simplified habit reversal procedure consisting of awareness training, competing response training, and social support. Treatment resulted in an immediate reduction to near-zero levels of hair pulling, with one to three booster sessions required to maintain these levels. The results were maintained from 18 to 27 weeks posttreatment, although 1 participant reported difficulty at follow-up. The effectiveness of simplified habit reversal and suggestions for future research are discussed.

Evaluation of a sexual abuse prevention program for adults with mental retardation.

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' 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.

Brief application of simplified habit reversal to treat stuttering in children.

We evaluated a brief therapy protocol involving the simplified regulated breathing method as a treatment for stuttering in children. The simplified treatment included awareness training, competing response training, and social support. Treatment was implemented in a multiple baseline across subjects design for 5 boys between the ages of 5 and 11. Each child received a 1 h treatment session, and 1/2 h booster sessions as needed. Four of the 5 children reduced their stuttering to less than 3% stuttered words (the criterion for successful treatment) after one 1 h treatment session. These results were maintained for 3 of the subjects from 6 to 9 months posttreatment. Social validity measures revealed significant differences between ratings on baseline and posttreatment speech samples. Treatment acceptability and credibility measures indicated that the subjects' guardians found the simplified regulated breathing method a reasonable treatment for stuttering in children.

Augmenting simplified habit reversal with an awareness enhancement device: preliminary findings.

The chronic hair pulling of a 36-year-old woman with moderate mental retardation was initially treated with a simplified habit-reversal (SHR) procedure that consisted of awareness training, competing response training, and social support. When SHR did not produce large and sustained reductions in hair pulling, an awareness enhancement device was added, and it reduced hair pulling to near-zero levels in two settings. The results are discussed, and directions for future research with this device are provided.