A unified exponential-H family for modeling real-life data: Properties and inference.

The exponential distribution is one of the most widely used statistical distribution for reliability issues. In this paper, we introduce a novel family based on the exponential model, called the new exponential-H (NEx-H) family. The sub-models of the NEx-H family are capable of accommodating variable failure rates, as well as unimodal, bimodal, left-skewed, symmetric, right-skewed, and J-shape densities. The mathematical features of the NEx-H family are derived. The parameters of the NEx-Weibull distribution are estimated by using seven estimation methods. Detailed numerical simulations are presented. Based on our study, the maximum likelihood is the best estimation method for estimating the NEx-Weibull parameters. Three real-life data sets are fitted using the NEx-Weibull distribution. The NEx-Weibull model provides better fit as compared to some competing Weibull models.

Flow-tub model: A modified bathtub flood model with hydraulic connectivity and path-based attenuation.

Global climate change and sea level rise are increasing the risks of flooding for coastal communities. Probabilistic coastal flood risk analysis at regional or global scales requires flood models with relatively low data requirements and low computational costs. Bathtub inundation models, which compute flood depth as the difference between water level and ground elevation, are well-suited for large-scale flood risk analysis. However, these models may overestimate floods because they do not capture some of the relevant underlying hydrodynamic processes that govern flood propagation on land. We present Flow-Tub, a modified bathtub inundation model that integrates two hydrodynamic processes to improve the accuracy of the bathtub inundation model while retaining computational efficiency: hydraulic connectivity and path-based attenuation.1.Hydraulic connectivity ensures that inundation is restricted to areas connected to the water source.2.Path-based attenuation ensures that the modeled flood water depths are reduced along the flow paths to represent the effects of surface friction and the temporary nature of storm surges. We validate the Flow-tub model against a hydrodynamic model. We also compare results of the bathtub model and the Flow-Tub model, highlighting the improved accuracy in the estimation of flood depths in the latter.

Optimal decision theory for diagnostic testing: Minimizing indeterminate classes with applications to saliva-based SARS-CoV-2 antibody assays.

In diagnostic testing, establishing an indeterminate class is an effective way to identify samples that cannot be accurately classified. However, such approaches also make testing less efficient and must be balanced against overall assay performance. We address this problem by reformulating data classification in terms of a constrained optimization problem that (i) minimizes the probability of labeling samples as indeterminate while (ii) ensuring that the remaining ones are classified with an average target accuracy X. We show that the solution to this problem is expressed in terms of a bathtub-type principle that holds out those samples with the lowest local accuracy up to an X-dependent threshold. To illustrate the usefulness of this analysis, we apply it to a multiplex, saliva-based SARS-CoV-2 antibody assay and demonstrate up to a 30 % reduction in the number of indeterminate samples relative to more traditional approaches.

Reliability analysis of multicomponent stress-strength reliability from a bathtub-shaped distribution.

In this paper, inference for a multicomponent stress-strength model is studied. When latent strength and stress random variables follow a bathtub-shaped distribution and the failure times are Type-II censored, the maximum likelihood estimate of the multicomponent stress-strength reliability (MSR) is established when there are common strength and stress parameters. Approximate confidence interval is also constructed by using the asymptotic distribution theory and delta method. Furthermore, another alternative generalized point and confidence interval estimators for the MSR are constructed based on pivotal quantities. Moreover, the likelihood and the pivotal quantities-based estimates for the MSR are also provided under unequal strength and stress parameter case. To compare the equivalence of the stress and strength parameters, the likelihood ratio test for hypothesis of interest is also provided. Finally, simulation studies and a real data example are given for illustration.

Assessing age-related heart changes by comparing cases of sudden death during bathing and control cases in Japan.

We analyzed 400 deaths that occurred in the bathtub during a 10-year period in the central area of Kanagawa prefecture in Japan. There were 72 (18%) medico-legal autopsy cases. The average age at death was 76.4 ± 11.9 years. Drowning (n = 21, 70.8%) was the most common cause of death in the 72 autopsy cases. The study examined the bodies of 40 cases within a postmortem interval of 3 days. The mean age of the 40 cases of sudden death during bathing was 68.6 ± 12.5 years. Results revealed cardiac hypertrophy in 12 cases (30%), lipofuscin deposition in 39 cases (97.5%), basophilic degeneration in 12 cases (30%), anisocytosis of the nucleus of myocardial cells in 18 cases (45%), perivascular fibrosis in 17 cases (42.5%), amyloid deposits in 1 case, and aortic valve calcification in 1 case. The hearts of control subjects who had lived to 20-99 years were also examined; the frequency of each change was higher in people older than 70 years. There was no statistically significant difference in age-related cardio-pathological changes between cases of sudden death during bathing in people in their 70s and controls in their 70s. It can be concluded that this age-related histopathological index is not related to sudden death during bathing. A large number of elderly people, including those without heart disease, have died during bathing. Preventive measures against sudden death during bathing are strongly recommended, e.g., elderly people should not be left totally unsupervised while they bathe.

Some new results on bathtub-shaped hazard rate models.

The most common non-monotonic hazard rate situations in life sciences and engineering involves bathtub shapes. This paper focuses on the quantile residual life function in the class of lifetime distributions that have bathtub-shaped hazard rate functions. For this class of distributions, the shape of the α-quantile residual lifetime function was studied. Then, the change points of the α-quantile residual life function of a general weighted hazard rate model were compared with the corresponding change points of the basic model in terms of their location. As a special weighted model, the order statistics were considered and the change points related to the order statistics were compared with the change points of the baseline distribution. Moreover, some comparisons of the change points of two different order statistics were presented.

Deaths in Bathtubs in Japan: Forensic and Clinical Implications.

In Japan, deaths in bathtubs or bathtub deaths are frequently investigated as unnatural deaths. About 19,000 bathtub deaths occur annually in Japan. This pattern of death has become a social issue in forensic pathology and emergency medicine and public health. It is assumed that the death of an adult by drowning in a bathtub cannot be avoided due to disturbance of consciousness. The PubMed database was used for literature search using the retrieval words, "bathing "OR" bathtub "AND" submersion "OR" drowning "OR" death "OR" cardiopulmonary arrest". From the epidemiological characteristics and pathophysiological findings of bath mortality in Japan, three etiologies of impaired consciousness have been proposed: acute ischemic heart failure, heatstroke, and blood pressure fluctuation. Moreover, other causes such as epilepsy and alcohol or drug intake cannot be ignored as potential risks for death in a bathtub. It is also important to note the possibility of suicide and, although extremely rare, homicide in a bathtub. Despite research, the exact causal relationship between bathtub bathing and death remains unclear. Further, the cause of death by postmortem investigation is not always easily determined. Hence, it is desirable to carry out a field survey of causes of death, including bathing conditions, and, wherever possible, a complete autopsy survey. An exclusion of critical cases such as crime-related death, suicide, drug poisoning, and carbon monoxide poisoning is optimal. Of the many hypotheses about the causes of bathtub mortality, the most consistent hypothesis will be medically inferred from the death history, case findings, and test results.

A Closer Look at Bleach Baths: Evidence, Tub Size, and Instructions.

Dilute sodium hypochlorite (bleach) baths have been used in routine care for many dermatologic conditions, namely atopic dermatitis. The benefits of bleach baths in reducing bacterial carriage have been well documented; however, the instructions often require subjective interpretation of bathtub size and may result in varying concentrations of bleach. Herein, we review the evidence for use of bleach baths and provide a method for ensuring that proper bleach concentrations are achieved.

Synergic Effects of Surfactant and Chelating Agent on Stubborn Keratin Grime for Easy Cleaning.

We report on the synergic effect of surfactants and chelating agents on the mechanism to remove stubborn keratin grime (keratin-Ca), which is bound with calcium ions and one of the most difficult grimes to remove, in order to make it easier to clean bathtubs in less time and with less scrubbing. Our approach was to focus on keratin swelling, which we achieved by applying aqueous solutions with chelating agents and anionic surfactants, the combination of which greatly improved the swelling ratio, resulting in quick, easy removal of keratin-Ca with water rinsing and little scrubbing. For the swelling process, we added chelating agents and anionic surfactants to swell the keratin-Ca by both capturing calcium ions and improving solution permeation. Furthermore, we measured the structural change of the keratin-Ca during swelling by TD-NMR and confirmed that a certain combination of chelating agent and anionic surfactant improved swelling by affecting not only the amorphous part such as the keratin matrix, but also the crystalline part such as the intermediate filaments (IFs).

Bayesian and E-Bayesian Estimations of Bathtub-Shaped Distribution under Generalized Type-I Hybrid Censoring.

For the purpose of improving the statistical efficiency of estimators in life-testing experiments, generalized Type-I hybrid censoring has lately been implemented by guaranteeing that experiments only terminate after a certain number of failures appear. With the wide applications of bathtub-shaped distribution in engineering areas and the recently introduced generalized Type-I hybrid censoring scheme, considering that there is no work coalescing this certain type of censoring model with a bathtub-shaped distribution, we consider the parameter inference under generalized Type-I hybrid censoring. First, estimations of the unknown scale parameter and the reliability function are obtained under the Bayesian method based on LINEX and squared error loss functions with a conjugate gamma prior. The comparison of estimations under the E-Bayesian method for different prior distributions and loss functions is analyzed. Additionally, Bayesian and E-Bayesian estimations with two unknown parameters are introduced. Furthermore, to verify the robustness of the estimations above, the Monte Carlo method is introduced for the simulation study. Finally, the application of the discussed inference in practice is illustrated by analyzing a real data set.

Burn wounds after electrical injury in a bathtub: a case report.

BACKGROUND: Increased smartphone use among minors makes our population more prone to electrical injury. Despite regulations on electrical home safety standards, smartphones and chargers still pose a risk for severe injury among users. CASE PRESENTATION: We present a case of a patient with low-voltage electrical burns due to smartphone use in a bathtub. The 13-year-old Caucasian patient was using a smartphone plugged into the electrical grid while taking a bath. We report the burns and their treatment. We discuss the likely burn mechanism. CONCLUSIONS: Burn wounds after electrical injury due to smartphone use are rare. The presented case shows the danger of smartphone use in bathtubs.

When bathing leads to drowning in older adults.

INTRODUCTION: Bathing is the most problematic activity of daily living for aging adults, and the ability to perform it is influenced by physical capabilities that decrease with age. Drowning is an under-documented event related to bathing for older adults. This study investigates the circumstances of these tragedies, to prevent them. METHODS: Census of 2005-2014 bathtub drownings in the province of Quebec (Canada) involving victims aged 65+. Coroner's reports were analyzed using a grid based on factors previously associated with bath-related drownings in literature, iteratively modified. RESULTS: Among the 92 bathtub drowning victims inventoried, 42% were aged 65+. The average age of older victims is 79 (65-97, ±9 years). Main probable cause of drowning is a cardiac problem, although only 19% of victims had a medical history of heart disease. Most victims were alone in their apartment or residence when drowning occurred. Risky periods appear to be springtime, Sundays, and evenings. Despite expectations, relevant information about the physical environment is very scarce. CONCLUSIONS: At least 39 Quebecers, aged 65+, drowned in their bathtubs over a 10-year period. More older adults than children are victims of bathtub drownings in community-dwellings. It seems that bathing may induce heart distress, leading to an appreciable number of drownings. PRACTICAL IMPLICATIONS: Since cardiac health problems are present in these deplorable events, promoting access to safety devices in the environment (emergency button, grab bars) and modified personal hygiene habits (bathing chair, showering) might be potential ways to prevent drowning and improve safety in older adults while they perform their personal hygiene, an essential activity for health and human dignity.

Muscular hemorrhages around the scapula resulting from excessive upper extremity motion in cases of fatal drowning: autopsy findings for insights on manner of death.

Muscular hemorrhages around the scapula are frequently found in fatal drowning cases without injuries in the upper back at time of autopsy. The present study investigated the frequency of muscular hemorrhages around the scapula and determined the mechanism responsible for this phenomenon. Muscular hemorrhages around the scapula were found in 104 of 164 (63.4%) bodies assessed. Hemorrhage in the infraspinatus muscle was most common, followed by the supraspinatus muscle. These muscular hemorrhages were not associated with upper extremity injuries and were most frequently found in accidental drowning cases (78.7%), followed by cases of suicide (56.0%), and in natural disease prior to drowning (19.0%). We examined muscular hemorrhage around the scapula and cervical injuries that restricted the active motion of upper extremities in drowning cases. The vertebral level of cervical injuries were related to muscular hemorrhages around the scapula. These results suggested that muscular hemorrhages around the scapula were not a result of agonal convulsions but were caused by consciously active excessive motion of the upper extremities while drowning. Investigations of the muscular hemorrhages around the scapula can provide insights towards the manner of fatal drowning.

Sudden unexpected death in epilepsy in the bathtub.

OBJECTIVE: Sudden death in the bathtub occurs relatively frequently in Japan, particularly among elderly people. We hypothesize that sudden death in epilepsy occurring in the bathtub (SDEPB) can be distinguished from sudden death in nonepilepsy occurring in the bathtub (SDnonEPB), but is identical to sudden unexpected death in epilepsy (SUDEP). METHODS: Tokyo Medical Examiner's Office conducts postmortem examinations for all sudden and unexpected deaths in Tokyo. Clinical, social, and autopsy findings of 43 SDEPB were compared with 76 SDnonEPB, 50 SUDEP outside the bathtub, and Japanese forensic autopsy data as controls. RESULTS: Extension of the leg(s) outside the bathtub was seen in 33% of SDEPB, but none of SDnonEPB. Sitting position was seen less frequently in SDEPB (37%) than in SDnonEPB (64%). Lung weight and pleural effusion volume were significantly lower in SDEPB than in SDnonEPB. Age at death in SDEPB was significantly younger than that in SDnonEPB. Sudden death in epilepsy occurring in the bathtub showed no differences in lung weight and pleural effusion volume from SUDEP. Living with family was more frequent in SDEPB (73%) than in SUDEP (48%). Few antiepileptic drugs, infrequent seizures, and low rate of mental retardation were identical between SDEPB and SUDEP. Lung weight was significantly heavier in all three groups than in age- and sex- matched autopsy controls. CONCLUSIONS: Leg extension outside the bathtub, lower lung weight, and absence of pleural effusion distinguish SDEPB from SDnonEPB in elderly people. Sudden death in epilepsy occurring in the bathtub may represent a form of SUDEP occurring in the bathtub, rather than drowning despite submergence in the bathtub at discovery. Conditions for bathing require careful attention from physicians and relatives, even for patients with epilepsy with few medications and infrequent seizures, and without mental retardation.

Association between sudden unexpected deaths in bathtubs and ambient temperature among elderly Japanese adults: A time-series regression study.

BACKGROUND: Sudden unexpected deaths in bathtubs among elderly Japanese adults occur predominantly during the cold season. This study investigated the relationship between these deaths and bathing day temperature among elderly adults in Tokyo. METHODS: Data for 1408 cases of bath-related deaths from January 1 to December 31, 2015 were obtained from the Tokyo Medical Examiner's Office. We excluded 409 cases for the following reasons: criminal death, injury-related death, suicide, intoxication, non-sudden death, not bathtub-related death, out-of-bathroom death, subject aged under 65 years, undetermined bathing date, institutional housing, and bathing not at subject's home. Ultimately, 999 cases were analyzed. Daily mean temperature data were collected. A time-series regression study was performed to estimate the influence of sex, age, and bathing day temperature. Monthly changes in the population bathing in a bathtub were considered in the model. RESULTS: The relative risk (RR) of sudden unexpected death in a bathtub was 1.381 for males (95% confidence interval [CI]: 1.218-1.564) compared to females. The RRs were 4.182 (95% CI: 3.523-4.986) and 9.382 (95% CI: 7.836-11.273) among those aged 75-84 years and ≥85 years, respectively, compared to among those aged 65-74 years. The RR increased to 1.092 (95% CI: 1.082-1.102) as the daily mean temperature decreased by 1 °C. CONCLUSION: Sudden unexpected death in a bathtub correlated with bathing day temperature among elderly Japanese adults, and extremely low temperature, male sex, and older age increased the risk of such death. Our findings provide insight into preventing sudden unexpected deaths in bathtubs.

Bathtub drowning mortality among older adults in Japan.

We examined the bathtub drowning mortality among older adults in Japan. Mortality data from Japan and 30 other Organization for Economic Co-operation and Development (OECD) countries were extracted from World Health Organization Cause of Death Query Online. During 2012-2014, unintentional drowning mortality rates in Japan were 9.5, 28.2 and 39.7 per 100,000 population for adults aged 65-74, 75-84 and ≥85 years, respectively-rates highest among the 31 OECD countries. In total, 6377 older adults aged ≥65 years died from unintentional drowning in 2014, of which 4857 (76%) deaths involved bathtubs. During 1995-2014, the bathtub drowning mortality rate for adults aged ≥65 years was stable in Japan. During 2011-2014, approximately 4800 older adults died from bathtub drowning annually. Death predominantly occurred 'while in a bathtub', rather than 'following a fall into a bathtub'. In 2014, 95% and 87% of bathtub drowning deaths among older women and men aged ≥65 years, respectively, occurred at home. In conclusion, bathtub drowning deaths at home is an important public health problem among older adults Japanese and efforts are needed to reduce these preventable deaths.

A two-time-scale point process model of water main breaks for infrastructure asset management.

Deterioration modelling has been a bottlenecking step towards risk-informed asset management of municipal water distribution networks. To close the gap, we proposed a two-time-scale (TTS) point process model on a pipe level for modelling and prediction of water main breaks. This paper presents the characterization, statistical parameter estimation, probabilistic features, and application of the model. Combining Poisson and renewal models into one, the proposed TTS process is characterized by a conditional intensity function of two time variables-one in a pipe clock for overall pipe aging and the other in a repair clock for local renewal. As a result, different aging patterns including the complicated bathtub-type behaviour can be modelled. A novel statistical method that combines data augmentation and Markov Chain Monte Carlo was developed for model estimation to deal with partially missing event histories. A case study using real-life data collected from a regional municipality in Canada was presented to illustrate the application of the proposed model. The modelling process ranging from model estimation, verification, validation, and updating to application in asset management was thoroughly demonstrated. This study also demonstrated that one must use the full distributions of the parameters to obtain an unbiased prediction of mean number of water main breaks. The proposed model was also compared with the Poisson process model in terms of break intensity, survival probability, mean cumulative number of breaks, and mean annual number of breaks. The implications of the different results to asset management were carefully discussed as well. Last, the ability of the proposed model to capture the maintenance effectiveness of pipe repair was proven. This work represents a solid advancement towards holistic assessment of the aging risk of a municipal water distribution network.

Changes in Body Temperature and Arterial Blood Flow Rate of 42°C Bathing Comparison of a Hot Spring Plunge Bath and Home Bathtub Bath / 日本温泉気候物理医学会雑誌

  【Introduction】One of the effects of the hot spring provides worm temperature. This effect raises temperature, and temperature control function operates and causes increase of the bloodstream. This time, these changes examined the thing by the size of the bathtub and the spring quality of the hot spring.   【Subjects and Methods】The subjects were 10 healthy adult men (mean age: 25.2 years). They bathed for 10 min in bathtubs at 42°C. The enforcement used plunge bath (approximately 1,700 L: simple alkaline hot spring) and home bathtub (approximately 300 L: hot water, 0.1% artificially chlorinated spring). Measurement item of the maximum arterial blood flow rate using the Ultrasonic Rheometer Smart Doppler 45, deep body temperature using the deep body temperature monitor core temperature CM-210, I compared each value 10 min during the bathing, and during a 10-min, 20-min, 30-min resting period after bathing, furthermore, I found the conjugation on each condition resting period after bathing.   【Result】The rise in deep body temperature and maximum arterial blood flow rate showed the result that a hot spring of the plunge bath was more meaningful than the value of the home bathtub after 10 min of bathing. The deep body temperature of the hot spring of the plunge bath significantly rose from bathing 3 min after. In deep body temperature with the resting period after bathing, in the hot spring of the plunge bath, a meaningful rise was maintained in hot water 13 min for population chloride spring 16 min of the home bathtub for 15 min.  【Discussion】In thinks that a population spring let you maintain a temperature rise that it disturbs a drop of the water temperature by abundant quantity of water in the plunge bath that hot spring plunge bath had a bigger deep body temperature rise, maximum arterial blood flow rate than home bathtub, and the deep body temperature rise in the home bathtub was continued.

Maintenance decision making of medical equipment based on reliability bathtub curve / 国际生物医学工程杂志

Objective To analyze the current medical equipment maintenance management model and the existing problems.Methods According to the law of reliability bathtub curve,the maintenance decision of medical equipments was analyzed from the three failure period stages,including early failure period,accidental failure period and loss failure period.By taking breathing machines as an example,a maintenance decision analysis during accidental failures was conducted.Results Medical equipment problems are caused by a variety of reasons,including operational problem,technical problem and management problem.The operational problem is caused by maintenance delays,lack of maintenance,and non-standard operations.The technical problem was caused by a wide variety of medical equipment and complex maintenance manuals.The management problem was caused by lacking of scientific management in equipment maintenance and updates.Conclusions For different stages of medical equipment,the impact factors are different and different maintenance strategies should be selected.

Measurement of electrocardiograms in a bath through tap water utilizing capacitive coupling electrodes placed outside the bathtub wall.

BACKGROUND: Taking a bath sometimes poses a risk for subjects with chronic cardiopulmonary disorders, due to the thermal effect and water pressure on his/her body. The ECG measurement would be helpful for the early recognition of abnormal cardiac beats and respiratory conditions. This paper describes a new attempt to improve on previous bathtub ECG measurement techniques that had electrodes placed inside the bathtub that were intrusive to the subjects' bathing experience. This study is concerned with the initial development of a method to measure an electrocardiogram (ECG) through tap water without conscious awareness of the presence of electrodes that are placed outside the bathtub wall. METHODS: A configuration of capacitive coupling electrodes placed outside the bathtub was designed so that the electrodes could be hidden. The capacitive coupling was made from the electrodes to the water through the bathtub wall. Two electrodes with an active shielding amplifier covered further by an electromagnetic shield were fixed to the outside surface of the bathtub wall, near the bather's right scapula and left foot. The potential difference between these two electrodes, similar to the bipolar lead-II ECG, was amplified to obtain raw signals inclusive of ECG/QRS components. Respiration intervals were also derived from ECG/RR intervals. Comparison experiments between this bathtub method and conventional direct methods with spot-electrodes and a chest-band sensor were made using 10 healthy male volunteers (22.2 ± 0.98 years). RESULTS: The ECG signal was detectable through tap water as well as water with differing conductivity resulting from mixing bathwater additives with the water. ECG signals and respiration curves derived from ECG/RR intervals were successfully obtained in all subjects. The intervals of the ECG/RR and respiration obtained by the bathtub system and by the direct method were respectively agreed well with each other. CONCLUSION: The ECG signal, in particular ECG/QRS components, were successfully detected utilizing capacitive coupling electrodes placed outside the bathtub wall. Also, the ECG/RR and respiration intervals were determined with reasonable accuracy as compared with the conventional direct methods.