Mean Life Research Articles

Amputated Life Testing for Weibull-Fréchet Percentiles: Single, Double and Multiple Group Sampling Inspection Plans with Applications

When a life test is terminated at a predetermined time to decide whether to accept or refuse the submitted batches, the types of group sampling inspection plans (single, two, and multiple-stages) are introduced. The tables in this study give the optimal number of groups for various confidence levels, examination limits, and values of the ratio of the determined experiment time to the fixed percentile life. At various quality levels, the operating characteristic functions and accompanying producer's risk are derived for various types of group sampling inspection plans. At the determined producer's risk, the optimal ratios of real percentile life to a fixed percentile life are obtained. Three case studies are provided to illustrate the processes described here. Comparisons of single-stage and iterative group sampling plans are introduced. The first, second, and third sample minimums must be used to guarantee that the product's stipulated mean and median lifetimes are reached at a certain degree of customer trust. The suggested sample plans' operational characteristic values and the producer's risk are given. In order to show how the suggested approaches based on the mean life span and median life span of the product may function in reality, certain real-world examples are examined.

Growth, maturity, reproduction, and life expectancy in ex-situ pacific walruses (Odobenus rosmarus divergens)

BackgroundPacific walruses are found in Arctic regions of the Chukchi and Bering Sea where rapid changes in environmental conditions resulting in loss of sea ice are occurring. Therefore, accurate life history data are crucial for species management plans and longitudinal data collected over the lives of individual walruses housed in zoos and aquaria provide otherwise difficult to obtain biological information.ResultsWhile similar at birth, Gompertz regression curves indicated that males grew faster than females (p < 0.0001) in weight (99 kg vs 57.6 kg/y) and length (26.9 cm vs 26.3 cm/y) with physical differences being detected by age 3 for weight and age 7 for length. Males reached adult weight at 13.5 ± 3.3 y and females by age 12.3 ± 2.3 y. The mean age at first ovulation and at first conception occurred at 8.8 y and 9.6 y. Greater than 75% of all conceptions and calving occurred between February and March and from May to June, respectively. Mean gestation lasted 423 d and false pregnancies lasted at least 169 d with a decrease (p < 0.05) in serum progesterone concentration between false pregnancy and pregnancy occurring within 6 months after ovulation. Based on these results, we estimated embryonic diapause to last from 120 to 139 days, and fetal growth last ~ 284 days. All males older than 8 y had an increase in serum testosterone and body weight that was highest in February and lowest in July. Overall, no differences were observed between male and female survival, with a mean (± SEM) life expectancy of 19.5 ± 1.5 y, respectively. Currently, the oldest male and female captive walruses are 40 and 43 y, respectively.ConclusionsData provided herein include details of life history characteristics of zoo and aquaria housed walruses that are useful for wild population recovery models. In particular, results on survivorship and the identification of the most vulnerable period for calf survival can help with model development and suggests that for recovery to occur birthing locations for this species must be protected.

An attribute control chart for the inverse Weibull distribution under truncated life tests

Statistical Process Control (SPC) is applied to monitor production processes in order to discover any problems or issues that may arise during the production process and to help in finding solutions for these issues. In this paper, we consider a situation in which the product's quality, as measured by its lifetime, is monitored. Since the monitoring requires life tests to be performed and this may take relatively long time, the test time is truncated at some pre-specified time t0, chosen to be related to the product's target mean life. This results in a truncated life test. The number of failures during the life test is used as an indicator of the quality of the product. We consider the situation in which the lifetimes follow the Inverse Weibull distribution. A control chart is proposed for this specific situation, thus extending the applicability of control charts methodology to situations involving truncated life tests. Simulation techniques has been employed to obtain the quantities needed for constructing the control chart with the aim that the average run length (ARL) is close to its target value. The control chart is evaluated by obtaining the ARL values when the process is out-of-control for various values of the shift coefficient. We obtained the coefficients of the control limit and the truncation coefficient for different sample sizes and average run length target values. An example on the application of the proposed control chart is provided.

Ceramides from Sea Red Rice Bran Improve Health Indicators and Increase Stress Resistance of Caenorhabditis elegans through Insulin/IGF-1 Signaling (IIS) Pathway and JNK-1.

The antiaging effects of sea red rice bran in vivo, a new saline-tolerant sea rice byproduct containing high levels of ceramides (Cers), remain unknown. This study aimed to explore the antiaging effects exerted by Cers from sea red rice bran on Caenorhabditis elegans, assess its health indicators as well as tolerance, and then reveal the mechanism of action of Cers in prolonging the mean life span through genetic studies. The results indicated that the mean life span of Cers-treated C. elegans were dose-dependent in the range of 0.10-0.50 mg/mL. Additionally, Cers improved nematode motility, reduced lipofuscin accumulation, and enhanced resistance to heat stress and antioxidant enzyme activity. Genetic studies showed that Cers treatment had altered nematode gene expression. In addition, insulin/IGF-1 and jnk-1/mitogen-activated protein kinase (MAPK) signaling pathways successfully demonstrated the longevity effects of Cers intake. In short, these results suggest that Cers enhance the resistance of C. elegans and prolong its life span.

Influence of Seawater Salinity on the Survival, Growth, Development and Neonate Production of Scapholeberis mucronata (O. F. Müller) (Crustacea: Cladocera)

The effect of salinity on the survival, growth, development and neonate production of the cladoceran Scapholeberis mucronata (O. F. Müller) was studied by using Chlorella pyrenoidosa as feed at 1, 2, 3, 4 salinity gradients and control group according to the pre-experiment and median lethal concentration experiment. The acute effect of salinity on this species indicated that 4 and 4.5 was its limit superior of reproduction and survival. The survival rate and growth rate of individuals reared at 1 and 2 salinity gradients were higher than that of those reared at the other gradients. The mean size of the female adult decreased from 820 to 743 μm when the salinity increased from 1 to 4. Among individuals reared at 1 and 2, the intrinsic rate of natural increase (rm) of population was 1.021 and 0.903, respectively; the rate of egg production was 1.281 and 1.390, respectively; the cumulative egg production was 83.2 and 106.0 and the mean life span was 16.05 and 17.30, respectively. These values of life history parameters were higher than those of individuals reared at 3. No eggs were produced by females reared at 4 during the whole experiment. Furthermore, individuals reared at 1 and 2 had faster embryonic development. The above results implied that S. mucronata is relatively well adapted to low-salinity conditions (1–2). Resting egg formation and sexual reproduction did not occur at all the tested salinity gradients.

Is life expectancy higher in countries and territories with publicly funded health care? Global analysis of health care access and the social determinants of health.

To better understand factors influencing life expectancy, this paper examines how the availability of publicly funded health care in a country and multiple social determinants of health impact longevity of life. In this descriptive statistical analysis, data regarding publicly funded health care, life expectancy, and social determinants of health were obtained for 196 countries and 4 territories. Social determinants included 10 indicators detailing country-level information to represent 5 key categories: economic stability, education, health & health care, neighbourhood & built environment, and social & community context. Analyses consisted of: 1) comparison of mean life expectancy among countries and territories with- and without- publicly funded health care; 2) correlations in life expectancy across social determinants by health care access and level of burden; and 3) correlations in life expectancy within social determinants for health care access by level of burden. Overall, life expectancy in countries and territories with- publicly funded health care (Mean (m) = 76.7 years) was significantly longer compared to countries and territories without- publicly funded health care (m = 66.8 years, P < 0.0001). For each social determinant, we observed longer life expectancy continued to be associated with publicly funded health care access across stratum (P < 0.0001), but difference in years of life expectancy existed both by burden of social determinant, as well as access to health care within quartiles of burden (Publicly funded care (yes): 68.12-80.88 years, (no): 62.39-77.33 years, all P < 0.05). Both social determinants as well as the availability of publicly funded health care were individually and simultaneously associated with mean longevity of life between countries and territories worldwide. These findings demonstrate how, if made widely available, publicly funded health care could extend longevity of life. If combined with programs to reduce the burden of social determinants, a substantial impact can be made to promote more equitable distribution of life expectancies across the world. Ultimately, both access to publicly funded care and reducing inequalities in social determinants are needed in order to promote longer and healthier aging in populations worldwide.

A Moment Inequality for the NBRULC Class: Statistical Properties with Applications to Model Asymmetric Data

In this paper, the moment inequalities for some aging distributions are derived based on a mathematical class entitled “a new better than renewal used in Laplace transform order in increasing convex order class (NBRULC)”. The introduced inequalities can be utilized as a new mathematical test for the exponentiality property versus NBRULC. If the mean life is finitely based on these inequalities, then all higher-order moments exist. Pitman’s asymptotic efficiency of the new mathematical test is derived and studied in detail for some asymmetric probability models. The new mathematical test’s power is estimated in reliability studies for a few well-known alternative asymmetric models. The problem in the case of right-censored data is also handled. After that, applying the suggested test to practical issues is demonstrated using asymmetric, real datasets.

Laboratory life cycle of Ornithodoros puertoricensis (Ixodida: Argasidae) collected in the Colombian Caribbean.

Three studies on the biology of Ornithodoros puertoricensis are available in the literature, using different hosts and incubation temperatures. In a previous study, we identified O. puertoricensis in the Colombian Caribbean. The aim of the present work was to analyze life cycle data along one generation from these specimens under laboratory conditions. Eggs of O. puertoricensis were collected in between fragments of bahareque material in a rural dwelling in the municipality of Planeta Rica (Córdoba Department, Colombia), and transported to the laboratory. All post-egg stages (i.e., larvae, nymphs, and adults) were incubated at 27°Cand 85% RH and fed on laboratory mice (Mus musculus). Sixteen engorged larvae were obtained to start a laboratory colony. Average feeding period for larvae was 4.6 days (4-5). The first nymphal instar (N1) did not require feeding and the subsequent nymphal stages (N2, N3, and N4) and adults had feeding periods ranging from 55 to 75min. Average pre-molting period in nymphs was 15 days (10-21). Most of the N3 molted to males and all N4 molted to females. Two gonotrophic cycles were recorded: the first had a preoviposition period of 12 days (7-18) and produced 190 eggs (171-223), the second lasted 6.6 days (6-7) and produced 146 eggs (104-201). The mean life cycle duration (from parental eggs to F1 eggs) was 70.7 days (58.7-82.7) without fasting periods. The collected data agree with previous studies even with differences in hosts and maintenance conditions.

Self-esteem, optimism and their associated factors among Optometry students at the University of Lahore

BACKGROUND &amp; OBJECTIVE: Self-esteem and optimism are important for students’ success. Our objectives were (a) to determine self-esteem and life-orientation (optimism) levels among Optometry students in the Department of Optometry &amp; Vision Sciences at the University of Lahore (UoL) (b) to investigate associations between sociodemographic factors, self-esteem, and optimism.&#x0D; METHODOLOGY: This cross-sectional study was conducted during November 2021 to December 2021 at the Department of Optometry and Vision Sciences, UoL. A total of 168 Optometry students were recruited by convenience sampling. Self-esteem was estimated using Rosenberg Self-Esteem Questionnaire. Life Orientation Test-Revised (LOT-R) questionnaire was used to measure optimism. Ethical approval was obtained from the Institutional Review Board of the UoL. Chi-square was used to determine associations between sociodemographic variables, self-esteem, and optimism.&#x0D; RESULTS: Mean self-esteem score was 18.48±3.86 (range:8-30). About 20% of students had low self-esteem. The mean life orientation score was 14.15±2.8 (range:5-24). About 43% of students had low optimism. Significant associations were found between self-esteem, reason of admission in the Optometry program with p-value=0.001, family income p=0.037 , choice of the Optometry program p=0.036, and reason of admission in the Optometry program 0.032.&#x0D; CONCLUSION: Low self-esteem and low optimism have been observed among a significant percentage of Optometry students at the UoL. Reason of admission in the Optometry program and family income were significantly associated factors. Students’ own decision to choose a study program may increase their self-esteem and optimism. Financial assistance for students from the low socioeconomic background may be a positive approach to boost their self-esteem and optimism. Teachers, parents, and counselors should support the students to increase their self-esteem and optimism.

Assessment of Anxiety and Burden on caregivers for haemodialysis patients in southern Punjab, Pakistan

The aim of present study is to assess anxiety and depression experienced by unpaid caregivers of chronic haemodialysis patients suffering from end-stage renal failure (ESRF). The evaluation of factors influencing anxiety and depression and care-giving burden was performed. In the present study, non-paid primary caregivers (218 study participants) of patients with ESRF receiving haemodialysis, who were providing care (minimum 6 months and up to 5 years) were interviewed by using Aga Khan University Anxiety and Depression Scale (AKUADS) and the carer’s burden of peritoneal dialysis patients (CSCDP) questionnaire. According to the scoring of AKUADS, 90.4% caregivers were found to be experiencing significant anxiety and depression. From assessment of demographic factors collected using the AKUAD scale, it was found that female gender was more in number (44%), wedded (72.01%), with a mean life span of 38.5 ± 2 (SE) years, and having monthly income below average. The main relationships of caregivers with patients, was life partners (38%) and parents (18.2%). The highest depression levels were found in mothers as attendants (67%), caregivers of age less than 30 years (22 %) and caregivers of elderly patients (87%). The outcome of this study has revealed a need to plan policies to support unpaid caregivers as well as the patients

Life Cycle GHG Perspective on U.S. Natural Gas Delivery Pathways.

Recent emission measurement campaigns have improved our understanding of the total greenhouse gas (GHG) emissions across the natural gas supply chain, the individual components that contribute to these emissions, and how these emissions vary geographically. However, our current understanding of natural gas supply chain emissions does not account for the linkages between specific production basins and consumers. This work provides a detailed life cycle perspective on how GHG emissions vary according to where natural gas is produced and where it is delivered. This is accomplished by disaggregating transmission and distribution infrastructure into six regions, balancing natural gas supply and demand locations to infer the likely pathways between production and delivery, and incorporating new data on distribution meters. The average transmission distance for U.S. natural gas is 815 km but ranges from 45 to 3000 km across estimated production-to-delivery pairings. In terms of 100-year global warming potentials, the delivery of one megajoule (MJ) of natural gas to the Pacific region has the highest mean life cycle GHG emissions (13.0 g CO2e/MJ) and the delivery of natural gas to the Northeast U.S. has the lowest mean life cycle GHG emissions (8.1 g CO2e/MJ). The cradle-to-delivery scenarios developed in this work show that a national average does not adequately represent the upstream GHG emission intensity for natural gas from a specific basin or delivered to a specific consumer.

Update on cystic fibrosis : From neonatal screening to causal treatment

Cystic fibrosis (CF) is a multiorgan disease caused by mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. Approximately 90% of the morbidity and mortality are caused by pulmonary involvement. The mean life expectancy of patients with CF in 2020 was more than 52 years in Germany. The introduction of neonatal screening for CF and the development of a causally acting CFTR modulator treatment have clearly improved the prognosis of these patients. As an introduction, this article describes important aspects of CF in this context in order to go into details of the CF neonatal screening which was introduced in Germany in 2016.

A Study Of Sociodemographic Profile Of The Patients Undergoing Hip Joint Replacement In A Tertiary Hospital In Central India

Hip arthroplasty made a revolution the field of orthopedics as the earlier thought of painful conditions like osteoarthritis or rheumatoid arthritis could now be solved by replacing the damaged joint with an artificial joint which dramatically improves the pain of the patient and the person who could barely walk due to pain starts walking again pain free. This magical medical innovation has changed lives of many worldwide. As the mean life span of the population is increasing, the diseases attributed to the age like osteoarthritis is also increasing and hence the scope for joint replacement is boundless.This study was an observational study to study the socio-demographic profile of the patients undergoing hip replacement arthroplasty in a tertiary hospital in central India.Methodology: This study was a record based observational study conducted retrospectively in the department of Orthopaedics in a tertiary care hospital in central India from 1st May 2021 to 30th April 2022. Sample Size of 50 patients were analyzed and pat clinical data was used from hospital records.Observation And Results: A total of 50 patients were studied in total. Out of them 30 were males and 20 were females. The mean age of the patients was 60.2 years. Out of the 50, 20 patients had yellow ration card i.e. belonging to lower socio economic status while 20 had saffron ration card and only 10 had white ration card. Majority of the population was Hindu (40%) followed by Muslims (30%), Buddhist (24%) and 6% were Christians, Sikhs and Jains. Majority of the population was educated up to 10th standard while 16% were illiterate. Osteoarthritis was the most common indication for hip joint replacement (70%).Conclusion: Due to better schemes for the poor, facilities, and equipment and the will to serve the poor, old age poor people can also get costly operations like hip joint replacement done to alleviate them from their sufferings.

Life Span, Cause of Death and Neoplasia in B6C3F1 Mice Exposed In Utero to Low- and Medium-Dose-Rate Gamma Rays.

Previously, we reported that while low-dose-rate (LDR) gamma-ray exposure to 20 mGy/day for the entire gestation period (gestation days 0-18) did not result in any significant effect in B6C3F1 pups up to 10 weeks of age when compared to the non-irradiated controls, exposure to medium-dose-rates (MDR, 200 and 400 mGy/day) resulted in growth retardation and gonadal hypoplasia, in addition to delayed ossification (only at 400 mGy/day). In the present work, we investigated the late effects of continuous in utero exposure to gamma rays at LDRs (0.05, 1.0 and 20 mGy/day) and at an MDR of 400 mGy/day, on life span, causes of death, neoplastic and non-neoplastic disease incidences in B6C3F1 mice. Reproductive parameters such as litter size and weaning rates was not significantly different among the LDR groups, but was significantly decreased in the MDR group, when compared to the non-irradiated controls. Mean life spans were not significantly different among the LDR exposed groups compared to the non-irradiated controls, whereas the life spans of those exposed to the MDR were significantly shorter than the non-irradiated controls. There was no significant difference in tumor spectra between the non-irradiated and LDR nor MDR irradiated groups. In mice exposed to MDR in utero, the over-all incidence rates shifted with increased incidences in the number of neoplasms of liver (both sexes) and endocrine (adrenals, pituitary and ovaries in females) origin with corresponding decreases in the incidence of malignant lymphomas (both sexes) and lung neoplasms (males). Multiple primary neoplasms were significantly increased only in females exposed to MDR. Results show that B6C3F1 mice exposed to gamma-rays in utero at LDRs of 0.05, 1 and 20 mGy/day for the entire gestation period (18 days) does not significantly alter lifespan, cause of death, neoplasm incidence rates and tumor spectra.

Exact likelihood ratio and Wald tests for the balanced joint progressive censoring scheme

AbstractRecently, the balanced joint progressive censoring (BJPC) for two samples has been introduced by the authors. This work comprises of developing testing of hypothesis for the BJPC scheme. An exact likelihood ratio test is developed to test the ratio of mean life times of two different products through joint life testing experiment. Along with this development, the Wald test has also been discussed, and an approximate power function has been used for power computation. Along with the study of testing of hypothesis, the optimal censoring scheme based on the power of the proposed tests has been determined. Meta heuristic variable neighborhood algorithm is exploited in this optimization task.

Describing the Function, Disability, and Health of Adults and Older Adults during the Early Coronavirus Restrictions in 2019: An Online Survey

The restrictions in 2019 due to Coronavirus impacted Canadians’ daily living, especially those at higher risk of compromised health conditions. This study aimed to describe the physical, psychological, and social well-being of adults with disabilities, and older adults from May to June 2020. Participants from the group of community-dwelling adults (≥19 years of age), who communicated in English, lived in British Columbia, and had Internet access via a computer, tablet, or smartphone with special focus on populations who had stroke, spinal cord injury and other disabilities were included. For measurement outcomes, an online survey was used to administer standardized measures of level of participation, mobility, anxiety and depression, boredom, resilience, technology readiness, social support, and social networks. Seventy-two participants were recruited, with a mean age (SD) of 61.2 (13.8). This study was comprised of two groups: the adult group consisted of individuals with disabilities under the age of 65 (48.6%) and the older adult group consisted of individuals over the age of 65 with and without self-identified disability (51.4%). There was no significant difference in the proportion of participation restriction between adult (83%) and older adult’ (81%) groups (p = 0.69). In the study population, 27.8% and 16.7% of participants exceeded the anxiety and depression cut-off scores, respectively. Boredom was experienced by 76.4% of participants. Participants’ mean (SD) resilience and life space scores were 72.4 (14.0) and 51.9 (24.0), respectively. The older adults (≥65 years) showed significantly lower depression (p = 0.012) and better resilience (p = 0.038), social support (p = 0.043), and social network (p = 0.021) than the younger adults. Issues with anxiety, boredom, participation, and life space activity were identified in both study groups. This information may provide supporting evidence when creating policies to mitigate existent health and social inequities.

New Properties of a Well-Known Antioxidant: Pleiotropic Effects of Human Lactoferrin in Mice Exposed to Gamma Irradiation in a Sublethal Dose.

We studied the effects of human lactoferrin (hLf), a multifunctional protein from the transferrin family, on integral (survival, lifespan during the experiment, body weight, behavior, subfractional compositions of blood serum) and systemic (hemoglobin level, leukocyte number, differential leukocyte count, histological structure of the liver and spleen) parameters of the body in mice after acute gamma irradiation in a sublethal dose. The experiments were performed on male C57BL/6 mice. The mice in the experimental groups were exposed to whole-body gamma radiation in a dose of 7.5 Gy from a 60Co source. Immediately after irradiation and 24 h after it, some animals received an intraperitoneal injection of hLf (4 mg/mouse). Single or repeated administration of hLf had a positive pleiotropic effect on irradiated animals: animal survival increased from 28% to 78%, and the mean life expectancy during the experiment (30 days) increased from 16 to 26 days. A compensatory effect of hLf on radiation-induced body weight loss, changes in homeostasis parameters, and a protective effect on the structural organization of the spleen were demonstrated. These data indicate that Lf has potential as a means of early therapy after radiation exposure.

The Effect of the “Kampung Bahari” Sustainable Development Program on the Kampong Tambak Lorok Community Semarang

Kampong Tambak Lorok is a place where fishers live on the north coast of Semarang City, facing the problem of tidal flooding and land subsidence. To overcome the issue at Tambak Lorok, the Semarang City Government launched an improvement program with the theme Kampung Bahari. Maritime means life related to the existence of the sea. The program is a medium-term infrastructure improvement. This study aims to determine the effect of infrastructure development through the Kampong Bahari program on the people of Tambak Lorok village. This study used as many as 20 household heads who were selected based on their length of stay in Tambak Lorok Village. The Likert analysis method was used to generate categories and indicators of influence variables based on public perception. Furthermore, the correlation analysis method determines the relationship between infrastructure development results and public perception. The analysis results show that the community strongly supports infrastructure development, especially those relating to the handling of tidal inundation. Communities directly affected by infrastructure development give a higher positive perception value. In addition, infrastructure development has changed the area’s morphology to be more organized and increased opportunities for the community to increase their income and their sustainability.

Design of Multiple Deferred State Repetitive Group Sampling Plans for Life Tests based on Generalized Gamma Distribution

Reliability sampling plans is a procedure to determine the acceptance or non-acceptance of the lot(s) of finished products by performing tests on the sampled items. Lifetime of individual items is a quality characteristic that can be treated as a continuous random variable and can be modeled by an appropriate continuous probability distribution. In this article, Multiple Deferred State Repetitive Group Sampling (MDSRGS) Plans for life tests under hybrid censoring with a provision to draw a random sample and to admit a maximum of one failure in the sample is formulated assuming that the lifetime random variable follows a Generalized Gamma (GG) distribution. A methodical procedure for the selection of the plan parameters using mean life criterion with the desired discrimination protecting the interests of the producer and the consumer in terms of the acceptable mean life and unacceptable mean life is evolved.

Estimating Genetic Variance in Life-Span Response to Diet: Insights From Statistical Simulation.

Several studies demonstrate genetic variation in response to dietary restriction (DR) by replicating treatments across isogenic lines/strains from genetic reference panels. These studies typically quantify the response to DR as an effect size, estimated for each strain separately (eg, the difference in mean life span between groups). Such "no-pooling" analyses are expected to systematically overestimate variation in response DR, principally by overlooking sampling variance. In contrast, "partial-pooling" analyses using mixed-effects models are less prone to this bias. I demonstrate these issues using simulations, which also show that partial-pooling analyses can improve replicability among studies. Regardless of the analyses used, estimates of among-strain variation will have low precision when sample sizes are small. A worked example using survival data in mice is given. Life-span studies using genetic reference panels always have to trade-off within- and among-strain replication owing to logistical challenges. The simulation presented can also be used to help design such studies through power analysis.