Cooperation for malaria control and elimination in the Guiana Shield.

The Guiana Shield, a small region of South America, is currently one of the main hotspots of malaria transmission on the continent. This Amazonian area is characterised by remarkable socioeconomic, cultural, health, and political heterogeneity and a high degree of regional and cross-border population mobility, which has contributed to the increase of malaria in the region in the past few years. In this context, regional cooperation to control malaria represents both a challenge and an indispensable initiative. This Viewpoint advocates for the creation of a regional cooperative mechanism for the elimination of malaria in the Guiana Shield. This strategy would help address operational and political obstacles to successful technical cooperation in the region and could contribute to reversing the regional upsurge in malaria incidence through creating a functional international control and elimination partnership.

Sex-related disparities in vehicle crash injury and hemodynamics.

Objective: Multiple studies evaluate relative risk of female vs. male crash injury; clinical data may offer a more direct injury-specific evaluation of sex disparity in vehicle safety. This study sought to evaluate trauma injury patterns in a large trauma database to identify sex-related differences in crash injury victims. Methods: Data on lap and shoulder belt wearing patients age 16 and up with abdominal and pelvic injuries from 2018 to 2021 were extracted from the National Trauma Data Bank for descriptive analysis using injuries, vital signs, International Classification of Disease (ICD) coding, age, and injury severity using AIS (Abbreviated Injury Scale) and ISS (Injury Severity Score). Multiple linear regression was used to assess the relationship of shock index (SI) and ISS, sex, age, and sex*age interaction. Regression analysis was performed on multiple injury regions to assess patient characteristics related to increased shock index. Results: Sex, age, and ISS are strongly related to shock index for most injury regions. Women had greater overall SI than men, even in less severe injuries; women had greater numbers of pelvis and liver injuries across severity categories; men had greater numbers of injury in other abdominal/pelvis injury regions. Conclusions: Female crash injury victims' tendency for higher (AIS) severity of pelvis and liver injuries may relate to how their bodies interact with safety equipment. Females are entering shock states (SI > 1.0) with lesser injury severity (ISS) than male crash injury victims, which may suggest that female crash patients are somehow more susceptible to compromised hemodynamics than males. These findings indicate an urgent need to conduct vehicle crash injury research within a sex-equity framework; evaluating sex-related clinical data may hold the key to reducing disparities in vehicle crash injury.

Self-reported exposure to dust and diesel exhaust, respiratory symptoms, and use of respiratory protective equipment among Arctic miners.

Arctic miners face significant risks from diesel exhaust and dust exposure, potentially leading to adverse respiratory health. Employers must limit harmful exposures, using personal protective equipment (PPE) as a last line of defense. This study explored the association between reported respiratory exposure and symptoms, and PPE training and usage. Data from the MineHealth study (2012-2014) included a total of 453 Arctic open pit miners in Norway, Sweden, and Finland. Participants answered questions on exposure to dust and diesel exhaust, respiratory symptoms, and PPE use, in addition to age, gender, BMI, smoking, and self-rated health. Estimated exposure to dust was common, reported by 91%, 80%, and 82% and that of diesel exhaust by 84%, 43%, and 47% of workers in Sweden, Finland, and Norway, respectively. Reported dust exposure was significantly related to respiratory symptoms (OR 2.2, 95% CI 1.3-3.7), diesel exposure increased the occurrence of wheezing (OR 2.6, 95% CI 1.3-5.4). PPE use varied between the studied mines. Non-use was common and related to reduced visibility, wetness, skin irritation and fogging of the respiratory PPE. Future research should employ more precise exposure assessment, respiratory function as well as explore the reasons behind the non-compliance of PPE use.

Calculation of additional load and deformation of the receiving well enclosure structure caused by shield tunneling.

The bulkhead additional thrust during shield tunneling, the force of friction between shield and soil, and the additional grouting pressure can cause additional stress in the surrounding soil, thereby disturbing existing buildings and structures. However, few studies focused on the disturbance situation when the shield tunneling machine approaches the receiving well. If the additional stress and deformation of the receiving well are too excessive, it could result in the collapse of the receiving well. Based on the two-stage method, this study derived the calculation formula of the additional stress and deformation of the receiving well enclosure structure caused by shield tunneling. Taking a shield machine receiving engineering as the context, this study established a numerical simulation model and compared theoretical calculation, the results of numerical simulation model and on-site monitoring data. Finally, the additional stress of the receiving well is analyzed. The research findings demonstrate that the theoretical prediction results, numerical simulation calculation results, and on-site monitoring data exhibit relatively small calculation errors, which validated the applicability of the theoretical prediction formula and numerical simulation model. As the distance between the shield machine and the receiving well decreases, the disturbance to the receiving well increases sharply. When the distance between the cutter head and the receiving well is less than three times the shield length, it is crucial to enhance the deformation monitoring of the receiving well. The primary factors affecting the additional load and deformation of the receiving well enclosure structure are the force of friction between shield and soil and the additional thrust of the cutterhead. The disturbance caused by the additional grouting pressure on the enclosure structure can be ignored.

Receptivity of providing firearm safety storage devices to parents along with firearms safety education.

Background: In the United States, 33% of households with children contain firearms, however only one-third reportedly store firearms securely. It's estimated that 31% of unintentional firearm injury deaths can be prevented with safety devices. Our objective was to distribute safe storage devices, provide safe storage education, evaluate receptivity, and assess impact of intervention at follow-up. Method: At five independent, community safety events, parents received a safe storage device after completing a survey that assessed firearms storage methods and parental comfort with discussions regarding firearm safety. Follow-up surveys collected 4 weeks later. Data were evaluated using descriptive analysis. Result: 320 participants completed the surveys, and 288 participants were gunowners living with children. Most participants were comfortable discussing safe storage with healthcare providers and were willing to talk with friends about firearm safety. 54% reported inquiring about firearm storage in homes their children visit, 39% stored all their firearms locked-up and unloaded, 32% stored firearms/ammunition separately. 121 (37%0.8) of participants completed the follow-up survey, 84% reported using the distributed safety device and 23% had purchased additional locks for other firearms. Conclusion: Participants were receptive to firearm safe storage education by a healthcare provider and distribution of a safe storage device. Our follow up survey results showed that pairing firearm safety education with device distribution increased overall use of safe storage devices which in turn has the potential to reduce the incidence of unintentional and intentional self-inflicted firearm injuries. Providing messaging to promote utilization of safe storage will impact a firearm safety culture change.

Are front crash prevention systems less effective at preventing rear-end crashes where trucks and motorcycles are struck?

OBJECTIVE: Automatic emergency braking (AEB) and forward collision warning (FCW) are effective at preventing rear-end crashes, but they may perform better in some rear-end crash scenarios than others. The goal of this study was to estimate the effects of front crash prevention systems equipped to passenger vehicles in crashes where another passenger vehicle, a medium/heavy truck, or a motorcycle is struck and compare effectiveness by struck vehicle type. METHODS: More than 160,000 two-vehicle rear-end crashes were identified where a passenger vehicle with or without FCW and AEB was the striking vehicle and another passenger vehicle, medium/heavy truck, or motorcycle was the struck vehicle. Poisson regression was used to estimate the effect of front crash prevention by struck vehicle type on rear-end crash rates per registered vehicle year, accounting for the state and year of the crash and the make, model year, class, and engine type of the striking vehicle. RESULTS: Front crash prevention was associated with a 53% reduction in rear-end crash rates when striking another passenger vehicle, which was significantly larger than the reductions of 38% when striking a medium/heavy truck and 41% when striking a motorcycle. Reductions in rear-end injury crash rates when striking a passenger vehicle also were larger than when striking a medium/heavy truck and when striking a motorcycle. DISCUSSION: If all passenger vehicles were equipped with FCW and AEB that were as effective in crashes striking a truck or motorcycle as they are in crashes with another passenger vehicle, over 5,500 additional crashes with medium/heavy trucks and 500 with motorcycles could potentially be prevented annually in the United States above what would be expected from current front crash prevention systems. Extending front crash prevention testing in consumer information programs to include motorcycle and truck targets could encourage auto manufacturers to improve performance in these crash scenarios.

Consumer experiences with crash avoidance feature repairs.

INTRODUCTION: Popularity of crash avoidance features is growing, but so too is confusion around how to repair them, how much repairs should cost, and who should pay for those repairs. This study's purpose was to capture how these issues are affecting consumers. METHOD: A total of 496 vehicle owners in the United States were surveyed online and by phone about their experiences repairing front crash prevention (n = 359), blind spot detection (n = 317), and/or driver assistance cameras (n = 348) equipped on their personal vehicles. RESULTS: Owners tended to have multiple reasons for repairs. Repairs due to vehicle (i.e., crash or windshield) damage corresponded with the greatest likelihood of post-repair issues, especially if calibration was performed, and higher out-of-pocket costs (possibly because of deductibles or other repair work). About half of respondents who had calibrations performed on features repaired because of vehicle damage reported persisting issues with the features after repair. Post-repair issues were more common for repairs performed at independent repairers than dealership service centers, yet similar feature calibration rates were reported for both types of repairers. More people went to dealership service centers than independent repairers, and these respondents were more likely to say they would return to this type of facility for a similar repair in the future. Although most repairers explained why repairs occurred, less than half of respondents said they completely understood the reasons given. CONCLUSIONS: There are new complications in the repair cycle affecting consumers. Post-repair issues are more prevalent than previously assumed, regardless of the crash avoidance feature repaired. PRACTICAL APPLICATIONS: Post-repair issues risk undermining consumer acceptance and the safety potential of critical features. Simplifying the repair process and establishing affordable and accessible centralized databases with repair specifications and instructions from the manufacturers would be a start to addressing industry-wide challenges.

Factors Affecting Gonadal Shielding Use Among Technologists in California.

PURPOSE: To assess the patient gonadal shielding practices of radiologic technologists in the state of California. METHODS: A survey invitation was sent via email to registered radiologic technologists in California to collect data to determine whether there were significant associations between gonadal shielding practices and various categorical variables, including patient sex, patient age, body part, availability of gonadal shielding protocols, availability of gonadal shields, and supervisor encouragement. RESULTS: There was a significant association between gonadal shielding protocol availability and supervisor encouragement of using gonadal shielding (P = .005) and between gonadal shielding availability and supervisor encouragement of using gonadal shielding (P < .001). Contrary to other studies in the literature, there was a significant difference between patient sex and the likelihood of gonadal shielding use, with participants indicating that they shield girls and women more often than they shield boys and men (P < .001). DISCUSSION: There was a sex-based difference in the frequency of gonadal shielding usage among the sample in this study. Also, supervisors providing accessible protocols and encouraging gonadal shielding can increase technologists' use of gonadal shielding. CONCLUSION: Gonadal shielding is the current Code of Federal Regulations standard, although most professional and scientific organizations support discontinuing shielding during abdominal and pelvic radiography examinations. Shielding of these areas is more likely to occur with the availability of gonadal shielding, supervisory encouragement, protocols mandating shielding, and state regulations.

Research on the dust-control technology of a double-wall attached-ring air curtain on an excavation face.

On the basis of the jet theory of airflow fields and the gas-solid two-phase flow theory, we studied the law of dust migration in a simulated dusting space. We used the control variable method and numerical simulation software to explore the airflow field and dust concentration distribution on the working surface of the dusting under different inlet wind speeds and different attached blades of the double-walled annular air curtain. We determined the speed of the inlet of the annular air curtain to be 30 m/s. When the angle of the attached blade was 30°, the dust concentration of the driver and other workers was controlled below 100 mg/m3, which produced the best dust control effect is the best. Using real data, we built a similar test platform to test the airflow field and dust concentration. Through data measurement and analysis, we proved that a dust control system with a double-wall attached-ring air curtain formed a circulating airflow field that could shield dust and effectively reduce dust concentration in the simulated space. The dust removal efficiency of total dust and exhaled dust reached 98.5% and 97.5%, respectively. We compared the test data and simulation results and concluded that the double-wall attached-ring air curtain could effectively ensure the safety of mine production and provide a better underground working environment for operators.

Mechanical, bioactive, and long-lasting antibacterial properties of a Ti scaffold with gradient pores releasing iodine ions.

The ideal bone implant would effectively prevent aseptic as well as septic loosening by minimizing stress shielding, maximizing bone ingrowth, and preventing implant-associated infections. Here, a novel gradient-pore-size titanium scaffold was designed and manufactured to address these requirements. The scaffold features a larger pore size (900 µm) on the top surface, gradually decreasing to small sizes (600 µm to 300 µm) towards the center, creating a gradient structure. To enhance its functionality, the additively manufactured scaffolds were biofunctionalized using simple chemical and heat treatments so as to incorporate calcium and iodine ions throughout the surface. This unique combination of varying pore sizes with a biofunctional surface provides highly desirable mechanical properties, bioactivity, and notably, long-lasting antibacterial activity. The target mechanical aspects, including low elastic modulus, high compression, compression-shear, and fatigue strength, were effectively achieved. Furthermore, the biofunctional surface exhibits remarkable in vitro bioactivity and potent antibacterial activity, even under conditions specifically altered to be favorable for bacterial growth. More importantly, the integration of small pores alongside larger ones ensures a sustained high release of iodine, resulting in antimicrobial activity that persisted for over three months, with full eradication of the bacteria. Taken together, this gradient structure exhibits obvious superiority in combining most of the desired properties, making it an ideal candidate for orthopedic and dental implant applications.

Optimization of Forward Collision Warning Algorithm Considering Truck Driver Response Behavior Characteristics.

Forward collision warning (FCW) systems have been widely used in trucks to alert drivers of potential road situations so they can reduce the risk of crashes. Research on FCW use shows, however, that there are differences in drivers' responses to FCW alerts under different scenarios. Existing FCW algorithms do not take differences in driver response behavior into account, with the consequence that the algorithms' minimum safe distance assessments that trigger the warnings are not always appropriate for every driver or situation. To reduce false alarms, this study analyzed truck driver behavior in response to FCW warnings, and k-means clustering was adopted to classify driver response behavior into three categories: Response Before Warning (RBW), Response After Warning (RAW), and No Response (NR). Results showed that RBW clusters tend to occur at long following distances (>19 m), and drivers applied braking before the warning. In RAW clusters, deceleration after warning is significantly more forceful than before warning. NR clusters occur at short distances, and deceleration fluctuates only slightly. To optimize the FCW algorithm, the warning distance was divided into reaction distance and braking distance. The linear support vector machine was used to fit the driver reaction distance. The long short-term memory method was used to predict braking distance based on each of the three response scenarios: R2 was 0.896 for RAW scenarios, 0.927 for RBW scenarios, and 0.980 for NR scenarios. Verification results show that the optimized truck FCW algorithm improved safety by 1 % to 5.1 %; accuracy reached 97.92 %, and the false alarm rate was 1.73 %.

Dental aerosol-producing treatments: Comparison of contamination patterns of face shields and surgical masks.

During the COVID-19 pandemic, dental face shields were recommended to protect the eyes. This study aimed to examine to what extent face shield and mask contamination differ when a pre-procedural mouth rinsing with Chlorhexidine (CHX) is conducted before treatment. In this prospective, randomized study, three groups of subjects were formed (rinsing with 0.1% CHX, water, or no rinsing (control) before aerosol-producing treatments). After each of the 301 treatments, the practitioner's face shield was swabbed with eSwab and the mask was brought into contact with agar plates. Sampling was done from the exterior surface only. Samples were cultured for 48 h at 35 °C under aerobic and anaerobic conditions. Bacteria were classified by phenotypic characteristics, biochemical test methods, and matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Colony-forming units were counted and mean values were compared (WSR, H-test, U-test, p < 0.05). Within each subject group, face shields showed significantly more contamination than surgical masks (control group: 350 CFU, 50 CFU; intervention water: 270 CFU, 40 CFU; intervention CHX: 250 CFU, 30 CFU). Comparison of face shields of the different subject groups did not reveal any statistically significant differences. However, CHX resulted in a statistically significant bacterial reduction on surgical masks compared to the water and control group (control: 50 CFU, intervention water: 40 CFU, intervention CHX: 30 CFU). Contamination of face shields and surgical masks was highest in the control group, followed by the water group, and lowest in the intervention group with CHX. Streptococcus spp. and Staphylococcus spp. dominated, representing the oral and cutaneous flora. Contamination of masks worn with or without face shields did not differ. Presumably, face shields intercept first splashes and droplets, while the masks were mainly exposed to bioaerosol mist. Consequently, face shields protect the facial region and surroundings from splashes and droplets, but not the mask itself. A pre-procedural mouth rinse with CHX had no statistically significant reducing effect on contamination of the face shield, but a statistically significant reducing effect was observed on contamination of the mask.

Adverse childhood experience and persistent insomnia during emerging adulthood: do positive childhood experiences matter?

BACKGROUND: Adverse childhood experiences (ACE) have been documented to have long-term impacts on sleep disturbances. However, less is known about how ACE co-occurs with positive childhood experiences (PCE) and modulate their effects on adult sleep disturbances, particularly in the context of persistent insomnia. Building on resilience theory, this study aims to examine the interplay between ACE and PCE and their effects on persistent insomnia during emerging adulthood. METHODS: A total of 2,841 emerging adults were recruited from the Taiwan Youth Project. Persistent insomnia during emerging adulthood was assessed using two adult surveys (mean age = 19.8 and 21.9). The ACE (10 items) and PCE (7 items) were obtained from the baseline survey (mean age = 13.8). A series of logistic regression analyses were conducted. RESULTS: Among the emerging adults, 29.22% had persistent insomnia. Consistent with the compensatory model, ACE and PCE exerted opposing effects on persistent insomnia during emerging adulthood. In line with the protective model, the negative effect of ACE is mitigated when individuals have high PCE. However, consistent with the challenge model, the protective effect of PCE on persistent insomnia was inhibited in individuals with four or more ACE. CONCLUSIONS: PCE serves as a protective factor, shielding emerging adults from the adverse effects of ACE on persistent insomnia. It is essential to prioritize positive experiences during early life to promote lifelong sleep health.

Home safety hazards associated with unintentional poisoning among children aged 0-5 years in Mongolia: A case-control study.

OBJECTIVE: To examine the association between home safety hazards and unintentional poisoning in children in Mongolia. METHODS: We conducted a case-control study using structured questionnaires to investigate safety behaviours, safety equipment use, and home hazards in households with or without children aged 0-5 years who had suffered from poisoning at home (i.e., cases and controls). We recruited 190 cases (105 medicinal and 84 non-medicinal poisonings, and one each) at the National Center for Maternal and Child Health and 379 controls in the communities between 1 March and 30 October 2021. RESULTS: There were large differences between cases' and controls' households in safety behaviours and home hazards: the failure to store all medicines out of reach of children (68% of cases vs. 25% of controls), the failure to store all medicines safely (out of reach, locked or non-existent) (61% vs. 22%), the failure to put all medicines away immediately after use (77% vs. 43%), the presence of things that a child could climb on to reach high surfaces (82% vs. 67%), the presence of medicines transferred into different containers (28% vs. 9%) and the presence of household products transferred into different containers (28% vs. 16%). These home safety hazards were strongly associated with poisoning after controlling for confounders. CONCLUSION: Children's risk of unintentional poisoning was strongly associated with the unsafe storage of potentially poisonous agents by caregivers and home hazards. Since unsafe storage is widespread, a fail-safe approach such as child-resistant closure of medicines and household products should be considered.

Pedestrian crash causation analysis and active safety system calibration.

Over 20 % of global crash fatalities involve pedestrians, but pedestrian crash causation and pedestrian protection systems have not been thoroughly developed or reliably tested. To understand the causation characteristics of pedestrian crashes, 398 pedestrian crashes were extracted from the China in-depth accident study (CIDAS), and most of these crashes were aggregated into five scenarios. The two scenarios with the highest proportion of crashes were analyzed by the driving reliability and error analysis method (DREAM) to identify high-risk causation patterns. From these patterns, three main contributing factors were identified: 1) extremely environmental light disturbance; 2) distracted driving caused by drivers' own thoughts; 3) drivers violating pedestrian yield law. Based on these patterns and factors, a pedestrian protection system was designed. It consists of a forward vision sensor and radar to sense the environment and the three-stage autonomous emergency braking (AEB) algorithm to automatically avoid pedestrian collisions. Crash scenarios from CIDAS data were recreated in MATLAB Simulink to test the pedestrian protection system proposed in this study. This system was found to reduce pedestrian crashes by more than 90 %. The optimal parameters for three AEB stages were obtained, with decelerations of 0.2 g, 0.3 g, and 0.6 g. This study designed an active safety system based on causation analysis of the vehicle-pedestrian crashes and calibrated the AEB algorithm of it, thus providing reference and insight for further development of pedestrian protection systems.

Criticism of Workplace Protection Barrier Face Covering Article Mischaracterizes ASTM Standard and its Potential Utility.

Editor's Note: This is a response to "Why a Workplace Barrier Face Covering is a Bad Idea" by Mark Nicas. DOI: 10.1177/10482911231193771.

[Improved Protective Equipment for NICU Portable Radiography].

We have been developing protective equipment for portable radiography in neonatal intensive care units because the portable radiography's X-ray tube is in close proximity to the head of the nurse who is assisting the patient. Although our initial protective-equipment design was highly effective, there were some concerns that it obstructed the view of the patient and was difficult to handle. To overcome this problem, we have developed two new types of protective device: a narrow-type 0.13 mmPb device, 17 cm long and 45 cm wide (weight 200 g); and a wide type with a wider core material, 45 cm long and 25 cm wide (weight 300 g), both of which can be hung from the collimator cover of mobile X-ray equipment. The measured protective effectiveness was 80.6% at head height for the wide type and 76.8% for the narrow type. A survey of nurses regarding the new protective devices revealed no significant differences between the two types in terms of visibility and whether the devices would be an obstacle when assisting patients. The nurses preferred the wider type, which offered better protection. Radiological technologists also liked that both types were easy to handle because the irradiation field could be adjusted even after the device was fitted. Both types of the new protective device are thus expected to be useful in clinical practice in terms of their high protective effect and improved ease of handling.

A Survey on Handling and Administration of Therapeutic Protein Products in German and Swiss Hospitals.

Protein products in hospitals often have to be compounded before administration to the patient. This may comprise reconstitution of lyophilizates, dilution, storage, and transport. However, the operations for compounding and administration in the hospital may lead to changes in product quality and possibly even impact patient safety. We surveyed healthcare practitioners from three clinical units using a questionnaire and open dialogue to document common procedures and their justification and to document differences in handling procedures. The survey covered dose compounding, transportation, storage and administration. One key observation was that drug vial optimization procedures were used for some products, e.g., use of one single-use vial for several patients. This included the use of spikes and needles or closed system transfer devices (CSTDs). Filters or light protection aids were used only when specified by the manufacturer. A further observation was a different handling of the overfill in pre-filled infusion containers, possibly impacting total dose. Lastly, we documented the complexity of infusion administration setups for administration of multiple drugs. In this case, flushing procedures or the placement and use of filters in the setup vary. Our study has revealed important differences in handling and administration practice. We propose that drug developers and hospitals should collaborate to establish unified handling procedures.

A case study of unavoidable accidents of autonomous vehicles.

Objective: Autonomous driving technology eliminates human errors, and thus it is a promising solution for reducing road traffic fatalities and injuries. While future autonomous driving technology may be able to reduce the number of collision accidents, it will not be able to avoid all collision accidents. This study is aimed to demonstrate why some accidents will still be unavoidable even with advanced perceiving and controlling capabilities.Methods: Because fully autonomous vehicles are currently in the laboratory stage, we used the prospective method to study the unavoidable accident of autonomous vehicles. Suitable traffic accident cases were screened from the China In-Depth Accident Study (CIDAS). Videos of the accidents were analyzed and the accidents were reconstructed using PC-Crash software. We assumed that target vehicle possesses near-perfect autonomous driving capabilities. Unavoidable accidents were determined based on vehicle dynamics and traffic constraints. The time from perceiving hazard to collision was calculated for each accident.Results: Among the 112 accidents screened, 15 cases of unavoidable accidents were identified. Three typical cases are presented in detail in this study. Based on the reasons why the target vehicles cannot avoid the collisions, we classified the unavoidable accidents into time-limit type and space-limit type. Time-limit means that vehicle cannot stop or steer out of danger in time, and space-limit means that the traffic environment does not have sufficient space for vehicle to avoid collision.Conclusions: Collision accidents will still occur even with perfect autonomous driving technology. We used the prospective method to investigate scenarios and characteristics of unavoidable accidents of autonomous vehicles. The time-limit type and the space-limit type were identified as two categories of unavoidable accidents. For the time-limit unavoidable accidents, the time from perceiving hazard to collision is typically not longer than 1.5s. The characteristics of unavoidable accidents and the estimated pre-crash warning time can provide some reference for establishing future occupant protection strategies. This study also showed the limitations of active safety and the necessity of passive safety.