The Use of Virtual Reality in Craving Assessment and Cue-Exposure Therapy in Substance Use Disorders

Craving is recognized as an important diagnosis criterion for substance use disorders (SUDs) and a predictive factor of relapse. Various methods to study craving exist; however, suppressing craving to successfully promote abstinence remains an unmet clinical need in SUDs. One reason is that social and environmental contexts recalling drug and alcohol consumption in the everyday life of patients suffering from SUDs often initiate craving and provoke relapse. Current behavioral therapies for SUDs use the cue-exposure approach to suppress salience of social and environmental contexts that may induce craving. They facilitate learning and cognitive reinforcement of new behavior and entrain craving suppression in the presence of cues related to drug and alcohol consumption. Unfortunately, craving often overweighs behavioral training especially in real social and environmental contexts with peer pressure encouraging the use of substance, such as parties and bars. In this perspective, virtual reality (VR) is gaining interest in the development of cue-reactivity paradigms and practices new skills in treatment. VR enhances ecological validity of traditional craving-induction measurement. In this review, we discuss results from (1) studies using VR and alternative virtual agents in the induction of craving and (2) studies combining cue-exposure therapy with VR in the promotion of abstinence from drugs and alcohol use. They used virtual environments, displaying alcohol and drugs to SUD patients. Moreover, some environments included avatars. Hence, some studies have focused on the social interactions that are associated with drug-seeking behaviors and peer pressure. Findings indicate that VR can successfully increase craving. Studies combining cue–exposure therapy with virtual environment, however, reported mitigated success so far

High Speed Shadowgraphy of Transparent Nozzles as an Evaluation Tool for In-Nozzle Cavitation Behavior of GDI Injectors

[EN] Gasoline Direct Injection (GDI) systems have become a rapidly developing technology taking up a considerable and rapidly growing share in the Gasoline Engine market due to the thermodynamic advantages of direct injection. The process of spray formation and propagation from a fuel injector is very crucial in optimizing the air-fuel mixture of DI engines. Previous studies have shown that the presence of some cavitation in high-pressure fuel nozzles can lead to better atomization of the fluid. However, under some very specific circumstances, high levels of cavitation can also delay the atomization process; spray stabilization due to hydraulic flip is the most well-known example. Therefore, a better understanding of cavitation behavior is of vital importance for further optimization of next generation fuel injectors. In contrast to the abundance of investigations conducted on the inner flow and cavitation patterns of diesel injectors, corresponding in-depth research on the inner flow of gasoline direct-injection nozzles is still relatively scarce. In this study, the results of an experiment performed on real-size GDI injector nozzles made of acrylic glass are presented. The inner flow of the nozzle is visualized using a high-power pulsed laser, a long-distance microscope and a highspeed camera. The ambiguity of dark areas on the images, which may represent cavitation regions as well as ambient air drawn into the nozzle holes, is resolved by injecting the fuel both into a fuel or gas filled environment. In addition, the influence of backpressure on the transient flow characteristics of the internal flow is investigated. In good agreement with observations made in previous studies, higher backpressure levels decrease the amount of cavitation inside the nozzles. Due to the high temporal and spatial resolution of the experiment, the transient cavitation behavior during the opening, quasi-steady and closing phases of the injector needle motion can be analyzed. For example, it is found that cavitation patterns oscillate with a characteristic frequency that depends on the backpressure. The link between cavitation and air drawn into the nozzle at the beginning of injection is also revealed.Mamaikin, D.; Knorsch, T.; Rogler, P.; Leick, P.; Wensing, M. (2017). High Speed Shadowgraphy of Transparent Nozzles as an Evaluation Tool for In-Nozzle Cavitation Behavior of GDI Injectors. En Ilass Europe. 28th european conference on Liquid Atomization and Spray Systems. Editorial Universitat Politècnica de València. 1027-1034. https://doi.org/10.4995/ILASS2017.2017.4639OCS1027103

Quantification of mixture composition, liquid-phase fraction and temperature in transcritical sprays

How do fuel and air mix, if a liquid fuel is injected into an environment featuring pressure and temperature that exceed the critical pressure and the critical temperature of the fuel? It is subject of current discussion on whether and if so when, the fuel/air-mixture becomes supercritical or not. We here report experimental data comprising three mixture properties that are relevant for the current debate, all spatially and temporally resolved throughout the spray and injection event: The overall composition of the fuel/air-mixture, the liquid fraction of the fuel/air-mixture, and the temperature of the liquid phase. To this end, we applied Raman spectroscopy and gave special attention to the signature of the Raman OH-band of ethanol, which we used as fuel. Its signature is connected to the development of a hydrogen bonded network between the ethanol molecules and thus extremely sensitive to thermodynamic state and temperature. Measurements were carried out in a high-pressure, high-temperature combustion vessel in a pressure range of 3−8 MPa and a temperature range of 573−923 K. For the highest set temperature we found ethanol in liquid-like mixtures that exceeded the mixture critical temperature. This is an indication of the existence of a single-phase mixing path

The influence of differential evaporation on the structure of a three-component biofuel spray

A high-pressure spray injected under gasoline engine conditions in a constant volume chamber is studied in detail using a three-dimensional computational fluid dynamics approach. Both single-component and ternary mixture (n-alkane and alcohols) spray results are compared with the experimental data from shadowgraphy, Schlieren imaging and phase-Doppler anemometry. Activity coefficient models are used to cover non-ideal thermodynamic effects occurring when mixtures of structurally dissimilar components such as alcohols and n-alkanes are considered. Here, the non-random, two-liquid and universal quasi-chemical functional group activity coefficients methods are applied. A ternary mixture composed of ethanol, n-butanol and n-hexane representing the research octane number (RON 95) of gasoline is considered and investigated in detail. To illustrate the non-ideal mixture effects, first the binary mixtures ethanol/n-butanol, n-butanol/n-hexane and ethanol/n-hexane are studied as subsets of the ternary mixture using a zero-dimensional single-droplet evaporation solver. Introducing a differential evaporation factor for multicomponent mixtures, the mixture segregation is characterized. Additionally, a separation factor indicating which component depletes first (volatility) is presented for both binary and ternary mixtures. The zero-dimensional results are then correlated with the three-dimensional computational fluid dynamics simulation results. Looking at the vapor–liquid equilibria of the different binary mixtures, the non-ideal effects are identified. The evaporation behavior of the binary mixtures is compared with the ternary mixtures in terms of droplet lifetimes, temperature and mixture decomposition, where the latter is characterized with the differential evaporation factor and separation factor. These results are afterwards compared with the three-dimensional computational fluid dynamics simulations, which are validated against the experimental data for single-component sprays regarding the liquid and vapor penetration depths. Finally, in the ternary mixture, n-butanol is replaced with iso-octane, the most widely used gasoline surrogate, to illustrate the differential evaporation behavior for a mixture with a higher alkane content than the ternary mixture used for the experiments. Strong non-ideal effects causing significant changes in the vapor composition are presented, as well as changes in the characterization factors, differential evaporation factor and the separation factor, respectively. These results are compared with the single-droplet simulations

Experimental investigation of flow field and string cavitation inside a transparent real-size GDI nozzle

Abstract Gasoline direct injection engines are highly dependent on the spray performance and associated combustion quality. The spray formation depends on many factors, namely internal flow characteristics, injection conditions, ambient conditions and fuel properties. There have been many studies performed to obtain a better understanding of these factors in recent years. In contrast to the others, studies on the internal flow characteristics are often performed numerically, as such, relevant experimental data is still lacking. Experimental investigations of the internal flow, such as flow turbulence, velocity distribution and cavitation are especially challenging under realistic conditions. Therefore, these conditions are generally simplified to diminish the demand for specialized experimental equipment and facilitate the measurements. In this regard, experimental data under relevant conditions are of high interest in the spray community. This work is focused on the internal flow study of multi-hole transparent nozzles under transient conditions at 1:1 geometrical scale. Injection pressure up to 100 bar is applied. The formation and development of string cavitation inside the nozzle hole are observed and presented in detail. For that, a novel ultra high-speed imaging technique at 5 MHz is applied. This technique in combination with the micro particle image velocimetry method, is then able to help to produce the velocity distribution of the internal flow. The velocity data is used further to reconstruct the pressure inside the nozzle by applying the Reynolds-averaged Navier–Stokes equations. Thus, the unique experimental data for the pressure distribution of the liquid fuel is obtained. Graphic abstrac

Comparison of physician referral and insurance claims data-based risk prediction as approaches to identify patients for care management in primary care: an observational study

BACKGROUND: Primary care-based care management (CM) could reduce hospital admissions in high-risk patients. Identification of patients most likely to benefit is needed as resources for CM are limited. This study aimed to compare hospitalization and mortality rates of patients identified for CM either by treating primary care physicians (PCPs) or predictive modelling software for hospitalization risk (PM). METHODS: In 2009, a cohort of 6,026 beneficiaries of a German statutory health insurance served as a sample for patient identification for CM by PCPs or commercial PM (CSSG 0.8, Verisk Health). The resulting samples were compared regarding hospitalization and mortality rates in 2010 and in the two year period before patient selection. No CM-intervention was delivered until the end of 2010 and PCPs were blinded for the assessment of hospitalization rates. RESULTS: In 2010, hospitalization rates of PM-identified patients were 80% higher compared to PCP-identified patients. Mortality rates were also 8% higher in PM-identified patients if compared to PCP-identified patients (10% vs. 2%). The hospitalization rate of patients independently identified by both PM and PCPs was numerically between PM- and PCP-identified patients. Time trend between 2007 and 2010 showed decreasing hospitalization rates in PM-identified patients (−15% per year) compared to increasing rates in PCP-identified patients (+34% per year). CONCLUSIONS: PM identified patients with higher hospitalization and mortality rates compared to PCP-referred patients. But the latter showed increasing hospitalization rates over time thereby suggesting that PCPs may be able to predict future deterioration in patients with relatively good current health status. These patients may most likely benefit from preventive services like CM

Identifying factors associated with experiences of coronary heart disease patients receiving structured chronic care and counselling in European primary care

BACKGROUND: Primary care for chronic illness varies across European healthcare systems. In patients suffering from coronary heart disease (CHD), factors associated with patients’ experiences of receiving structured chronic care and counselling at the patient and practice level were investigated. METHODS: In an observational study comprising 140 general practices from five European countries (Austria, Germany, the Netherlands, Switzerland and the United Kingdom), 30 patients with Coronary Heart Disease (CHD) per practice were chosen at random to partake in this research. Patients were provided with a questionnaire and the Patient Assessment of Chronic Illness Care (PACIC-5A) - instrument. Practice characteristics were assessed through a practice questionnaire and face to face interviews. Data were aggregated to obtain two practice scores representing quality management and CHD care, respectively. A hierarchical multilevel analysis was performed to examine the impact of patient and practice characteristics on PACIC scores. RESULTS: The final sample included 1745 CHD-patients from 131 general practices with a mean age of 67.8 (SD 9.9) years. The overall PACIC score was 2.84 (95%CI: 2.79; 2.89) and the 5A score reflecting structured lifestyle counselling was 2.75 (95% CI: 2.69; 2.79). At the patient level, male gender, more frequent practice contact and fewer related or unrelated conditions were associated with higher PACIC scores. At the practice level, performance scores reflecting quality management (p = 0.013) and CHD care (p = 0.009) were associated with improved assessment of the structured chronic care and counselling received. CONCLUSIONS: Patients’ perceived quality of care varies. However, good practice management and organisation of care were positively reflected in patients’ assessments of receiving structured chronic illness care. This highlights the importance of integrating patient experiences into quality measurements to provide feedback to health care professionals

The effect of transient needle lift on the internal flow and near-nozzle spray characteristics for modern GDI systems investigated by high-speed X-ray imaging

The development of the injector nozzle is a dynamic area in regard of several technical aspects. At first, the internal flow influences the near-field spray characteristics via various phenomena such as cavitation and turbulence. However, these phenomena are not fully understood due to their extremely fast, complex and multiscale nature. Furthermore, it governs the spray targeting inside the combustion chamber. High-speed X-ray imaging of GDI injector nozzles is performed in this study. The experimental results presented are related to the internal flow and primary breakup of discharged liquid jets. The injectors used are equipped with nozzles made of aluminum which have been specially developed for these investigations to enhance optical accessibility. The visualization of the needle motion, in-nozzle flow and the primary breakup region provides several exciting observations. First, the needle lift tracking exhibits short overshooting right before the steady-state of the injection phase. This event leads to a short-term, however, significant change in the associated performance of the breakup. This phenomenon is found to be a consequence of the transient behavior of the in-nozzle flow. It is shown that under some circumstances hydraulic flip may occur during this overshooting period. The primary jet breakup region is visualized and evaluated by means of image processing. Thus, the transient behavior of liquid jet expansion is quantified in the vicinity of the nozzle. It is observed that the liquid jet direction deviates from the hole axis already at the nozzle outlet, which is caused by internal flow characteristics

A tailored programme to implement recommendations for multimorbid patients with polypharmacy in primary care practices — process evaluation of a cluster randomized trial

Background: We developed and evaluated a tailored programme to implement three evidence-based recommendations for multimorbid patients with polypharmacy into primary care practices: structured medication counselling including brown bag reviews, the use of medication lists and medication reviews. No effect on the primary outcome was found. This process evaluation aimed to identify factors associated with outcomes by exploring nine hypotheses specified in the logic model of the tailored programme. Methods: The tailored programme was developed with respect to identified determinants of practice and consisted of a workshop for practice teams, elaboration of implementation action plans, aids for medication reviews, a multilingual info-tool for patients on a tablet PC, posters and brown paper bags as reminders for patients. The tailored programme was evaluated in a cluster randomized trial. The process evaluation was based on various data sources: interviews with general practitioners and medical assistants of the intervention group and a survey with general practitioners of the intervention and control group, written reports on the implementation action plans, documentation forms for structured medication counselling and the log file of the info-tool. Results: We analyzed 12 interviews, 21 questionnaires, 120 documentation forms for medication counselling, 5 implementation action plans and one log file of the info-tool. The most frequently reported effect of the tailored programme was the increase of awareness for the health problem and the recommendations, while implementation of routine processes was only reported for structured medication counselling. The survey largely confirmed the usefulness of the applied strategies, yet the interviews provided a more detailed understanding of the actual use of the strategies and several suggestions for modifications of the tailored programme. Conclusions: The tailored programme seemed to have induced awareness as a first step of behaviour change. Several modifications of the tailored programme may enhance its effectiveness such as conducting outreach visits instead of a workshop, improved targeting, provision of evidence, integration of tools into the practice software and information materials in tailored formats. Trial registration: This study is linked to an outcome evaluation study with the registration ISRCTN34664024, assigned 14/08/2013