Search Results (62)

Background: Sleep disturbances are highly prevalent, affecting approximately 21% of the European population, with chronic insomnia disorder estimated at 6%. Non-pharmacological alternatives to pharmacotherapy are needed. Sulfurous balneotherapy represents a potential intervention, yet real-world evidence remains limited. Objective: To explore changes in self-reported sleep quality following sulfurous balneotherapy at Terme di Saturnia (Italy). Methods: Retrospective single-arm observational study of 76 participants (mean age 47.3 years, 54% female) undergoing a 7–12-day consecutive balneotherapy cycle with daily sulfurous thermal water immersion sessions (60–90 min/session). The Oviedo Sleep Questionnaire (OSQ) was administered pre- and post-treatment. Participants were stratified by baseline insomnia severity into Group A (OSQ ≥ 22, n = 47) and Group B (OSQ < 22, n = 29). The primary outcome was change in OSQ insomnia score in Group A. Statistical analysis was performed using the Wilcoxon signed-rank test. Results: In Group A, insomnia severity decreased significantly from 26.4 ± 8.3 at baseline to 20.1 ± 7.5 post-treatment (Δ = −6.3, 95% CI: −7.9 to −4.7, p < 0.001, r = 0.54). Sleep satisfaction also improved significantly from 3.2 ± 1.1 to 4.6 ± 1.2 (Δ = +1.4, 95% CI: 1.1–1.7, p < 0.001, r = 0.60). In Group B, no statistically significant changes were observed, consistent with ceiling effects. However, in an open-ended question, 72.4% (21/29; 95% CI: 54.3–85.3) of Group B participants reported enhanced relaxation during the spa stay. Due to the single-arm observational design without control groups, the observed improvements cannot be distinguished from non-specific factors, including the vacation effect, reduced work-related stress, placebo and expectancy responses, regression to the mean, or the effects of warm water immersion itself independent of sulfurous mineral content. Conclusions: This exploratory study documents pre–post improvements in self-reported sleep quality in a cohort undergoing sulfurous balneotherapy during a spa vacation. The absence of control groups and unmeasured confounders precludes causal inferences. Future randomized trials with heated non-mineral water controls are needed to isolate specific therapeutic contributions of sulfurous thermal waters. Full article

Despite extensive research on queueing models in flexible manufacturing systems (FMS), few studies have simultaneously considered the heterogeneity of servers and the impact of synchronous working vacations on system performance. To fill this research gap, this study proposes a novel multi-server queueing model that uniquely integrates two-phase heterogeneous services with synchronous working vacation interruptions. The innovation lies in capturing the complex task processing mechanism where the two-phase service is provided by different servers, and they conduct working vacations synchronously when the system is empty and terminate vacations once the system population reaches a specified threshold. Based on the matrix-analytic approach, this research investigates the stability condition and the stationary distribution of the system. A key numerical finding is the diminishing marginal returns of server numbers, where exceeding an optimal count increases congestion, thereby degrading overall performance. The vacation interruption threshold l is also shown to significantly influence server state allocation. A comparative analysis of three different system configurations, demonstrates that dynamic server number or a vacation interruption threshold adjustment effectively mitigates congestion; and in order to enhance the system clearing capability, when vacations are longer, opting for multiple servers is preferable, whereas a single server is more suitable during shorter vacation periods. For cost optimization, three algorithms (CPSO, JAYA, MLS-JAYA) consistently converge to the same robust optimal solution for server count and vacation rate. Furthermore, to simultaneously minimize waiting time, we apply the MOEA/D algorithm to study the bi-objective optimization problem. Full article

Analysis of a crowdsourcing Markovian queue with phase-type service is considered in this paper. In this model, a customer not only receives service but also assists in delivery. In other words, in a retail environment, while some customers shop in-store, others place orders online or by phone and require home delivery. Store management can utilize online customers as couriers to complete these deliveries. However, because not every customer may agree to take part, a probabilistic element is included to capture the chances of their participation. The model also incorporates imperfect service, reflecting cases where deliveries may fail or require rework, and working breakdowns, representing partial disruptions in service capacity rather than complete stoppages. To analyze the system under steady-state conditions, matrix-analytic methods are applied. Numerical examples illustrate the significant benefits of incorporating these dynamics into traditional queueing models. Full article

In this paper, a $k/n\left(G\right)$ retrial system with multiple working vacations is considered, and a mathematical model of the system is established by supplementary variable method, and a dynamic analysis of the system is carried out. Firstly, the model is transformed into an abstract Cauchy problem in Banach space by introducing the state space, main operator and its definition domain. Secondly, the $C_0$-semigroup theory in functional analysis and the spectral theory of linear operators are used to prove that the main operator of the model generates a positive contraction $C_0$-semigroup, which leads to the existence of a unique, non-negative time-dependent solution of the system that satisfies the probabilistic properties. Finally, Greiner’s boundary perturbation idea and the spectral properties of the corresponding operators are used to show that the time-dependent solution strongly converges to its steady-state solution. Full article

This paper analyzes a finite-capacity $GI/M/2/N$ queue with two heterogeneous servers operating under a multiple working-vacation policy, Bernoulli feedback, and customer impatience. Using the supplementary-variable technique in tandem with a tailored recursive scheme, we derive the stationary distributions of the system size as observed at pre-arrival instants and at arbitrary epochs. From these, we obtain explicit expressions for key performance metrics, including blocking probability, average reneging rate, mean queue length, mean sojourn time, throughput, and server utilizations. We then embed these metrics in an economic cost function and determine service-rate settings that minimize the total expected cost via the Bat Algorithm. Numerical experiments implemented in R validate the analysis and quantify the managerial impact of the vacation, feedback, and impatience parameters through sensitivity studies. The framework accommodates general renewal arrivals ($GI$), thereby extending classical ($M/M/2/N$) results to more realistic input processes while preserving computational tractability. Beyond methodological interest, the results yield actionable design guidance: (i) they separate Palm and time-stationary viewpoints cleanly under non-Poisson input, (ii) they retain heterogeneity throughout all formulas, and (iii) they provide a cost–optimization pipeline that can be deployed with routine numerical effort. Methodologically, we (i) characterize the generator of the augmented piecewise–deterministic Markov process and prove the existence/uniqueness of the stationary law on the finite state space, (ii) derive an explicit Palm–time conversion formula valid for non-Poisson input, (iii) show that the boundary-value recursion for the Laplace–Stieltjes transforms runs in linear time $\mathcal{O}\left(N\right)$ and is numerically stable, and (iv) provide influence-function (IPA) sensitivities of performance metrics with respect to $({\mu }_1,{\mu }_2,\nu ,\alpha ,\varphi ,\beta )$. Full article

This research advances steady state analysis and cost optimization of the M/M/1/N single vacation queueing system with setup time, working vacation, and working breakdown. The server works at a lower service rate instead of stopping work completely during both the vacation period and breakdown period—a key distinction from traditional vacation and breakdown strategies, where the server typically halts operations entirely. The setup time exists between the idle period and the regular busy period. The finite quasi birth-and-death process of this queueing system model is established. The stationary probability vector of the system is calculated using the matrix geometric method. Performance measures, such as output variance, availability, throughput rate, and stationary probabilities, are obtained using the theory of the fundamental matrix and covariance matrix. A cost optimization model based on system performance measures is established. The sparrow search algorithm is adopted to solve the cost optimization model. Through numerical experiments, the influences of system parameters on system performance measures and cost optimization function are analyzed, and the efficiency of the sparrow search algorithm for solving the cost optimization model is verified. The experimental results affirm the effectiveness and practicability of the proposed method, which provides a better theoretical basis for the practical application of the queueing system in communication engineering and production systems. Full article

Background/Objectives: Occupational well-being and professional quality of life are essential for healthcare sustainability. While clinical staff are presumed to experience higher stress, few studies have compared their experience to that of non-clinical personnel within the same institution. Methods: This observational study involved 63 employees from an Italian research hospital: 36 healthcare workers in critical care and 27 administrative staff. Participants completed the Brief Coping Orientation to Problems Experienced Inventory (Brief COPE), an ad hoc organizational questionnaire, and the ProQoL Version 5 (administered to clinical staff only). Non-parametric tests (Mann–Whitney U and Chi-square) were used to explore group differences. Results: No significant differences emerged between groups in coping styles or strategies. Significant differences were observed only in reports of work-related injuries (42% of healthcare staff vs. 4% of administrative staff; p = 0.002) and perceived disruption caused by vacation requests (64% vs. 26%; p = 0.006). Other organizational indicators such as job dissatisfaction, intention to leave, or perceived managerial support did not differ significantly. ProQoL results showed that 53% of healthcare workers had moderate to high burnout, and 47.2% scored high on compassion fatigue, while only 2.7% showed high levels of secondary traumatic stress. Conclusions: Despite distinct operational contexts, healthcare and administrative staff reported broadly similar experiences in terms of coping and organizational well-being. These findings challenge assumptions of stark differences across professional roles and suggest that workplace well-being strategies should address the needs of both clinical and non-clinical staff. Full article

In this paper, we present an extensive literature review on queueing systems with working vacations. The concept of a working vacation generalises the concept of server vacations, which are time periods during which the server is absent and cannot serve waiting customers. During a working vacation, the server remains active, albeit at a reduced service rate. Our literature survey mainly highlights the structural properties of the Markov chains that underlie working vacation queueing models, as well as various methodological approaches to assessing the performance of queues with working vacations. Moreover, queueing games with working vacations and applications of queues with working vacations are discussed. Full article

With the advancement of science and technology, industrial robots have become indispensable equipment in advanced manufacturing and a critical benchmark for assessing a nation’s manufacturing and technological capabilities. Enhancing the reliability of industrial robots is therefore a pressing priority. This paper investigates the drive system of industrial robots, modeling it as a series system comprising multiple components (n) with a repairman who operates under a single vacation policy. The system assumes that each component’s lifespan follows an exponential distribution, while the repairman’s repair and vacation times adhere to general distributions. Notably, the repairman initiates a vacation at the system’s outset. Using the supplementary variable method, a mathematical model of the system is constructed and formulated within an appropriate Banach space, leading to the derivation of the system’s abstract development equation. Leveraging functional analysis and the $C_0$-semigroup theory of bounded operators, the study examines the system’s adaptability, stability, and key reliability indices. Furthermore, numerical simulations are employed to analyze how system reliability indices vary with parameter values. This work contributes to the field of industrial robot reliability analysis by introducing a novel methodological framework that integrates vacation policies and general distribution assumptions, offering new insights into system behavior and reliability optimization. The findings have significant implications for improving the design and maintenance strategies of industrial robots in real-world applications. Full article

Introduction: Work is an essential aspect of human life. However, high expectations from employers and clients, combined with time pressure and chronic stress, can contribute to burnout among employees in service professions. Aim of the Study: This study aimed to compare the prevalence of burnout syndrome between two occupational groups—corporate office workers and active nurses—and to assess the influence of socio-demographic factors on the level of burnout in both groups. Materials and Methods: The study was conducted among 330 participants, including 126 nurses (38%) and 204 corporate employees (62%). Data were collected using a standard questionnaire and the Maslach Burnout Inventory. The study period spanned from November 2018 to October 2019, and questionnaires were distributed via email. Results: The findings revealed that both corporate employees and nurses experience occupational burnout. Both groups predominantly exhibited moderate to high levels of emotional exhaustion (nurses: 66.67%, q2 = 20.5; corporate employees: 73.53%, q2 = 31.5) and low to moderate levels of personal accomplishment (nurses: 78.57%, q2 = 32.0; corporate employees: 87.75%, q2 = 27.0). Corporate employees showed significantly higher depersonalization scores (q2 = 13.50) compared to nurses (q2 = 5.0). The prevalence of burnout in both groups was influenced by socio-demographic factors, including having children, their place of residence, education, earnings, and job-related factors such as vacation availability, the frequency of work shifts, work systems, overtime, and overall job satisfaction. Conclusions: Service-oriented professions that involve caregiving and direct interpersonal interactions face comparable risks of occupational burnout. Despite differences in the nature and conditions of work, as well as tasks performed, both corporate employees and active nurses are vulnerable to burnout. High salaries were not confirmed as a protective factor against occupational burnout. Additionally, environmental factors, particularly those related to working conditions, played a significant role in the development of burnout syndrome, alongside individual factors. Full article

This research analyzes a multi-server retrial queue with two types of calls: working vacation and working breakdown. The incoming call may enter the retrial queue and attempt to seize a server after a random delay if all the servers are unavailable upon arrival. In its idle time, the server makes outgoing calls. All the servers take a synchronous working vacation when the system empties after regular service. The system may fail at any time due to disasters, forcing all the calls within the service area to leave the system and causing all the main servers to fail. When the main servers fail, the repair process begins immediately. The standby servers serve arriving customers at a lower level of service during the working breakdown or working vacation. For this model, we derive an explicit expression for the stationary distribution with the help of the quasi-birth-and-death process and the matrix geometric method. Further, the formulas of various system performance indices are developed. An application example is given and several numerical experiments are performed to verify the analytical results. We also perform the comparative analysis of retrial queues with/without two-way communication and two-way communication retrial queues with/without disasters. The results reveal that the proper consideration of outgoing calls to the server can reduce the average time spent in the buffer. Furthermore, a more reliable server reduces the server idle rate. Full article

Given the persistently high incidence of skin cancer, there is a need for prevention-focused information on the impact of long-term changes in ambient solar ultraviolet radiation (UVR) on human personal radiation exposure. The exposure categories of the UV Index linked to protection recommendations show long-term shifts in the frequency of occurrence with regional differences in direction and magnitude. The patterns of change for sites in the humid continental climate differ from those for sites in other climate zones such as the humid temperate or Mediterranean climate. The diversity of the individual exposures of indoor and outdoor workers can be described using probability models for personal erythema-effective UVR dose (UVD). For people who work indoors, the largest share of the total individual annual UVD is due to vacation, whereas for people who work outdoors, it is occupational exposure. The change in ambient UVDs at the residential locations is only partially reflected in the individual UVDs. For eight selected European sites between 38° and 60° northern latitude, the median of the individual annual total UVD (excluding travel) during the period 2009–2019 is 0.2 to 2.0% higher for indoor workers and 0.6 to 3.2% higher for outdoor workers compared to the period 1983–2008. Changes in the choice of an exemplary holiday destination offer both indoor and outdoor workers the potential to compensate for the observed long-term trend at their place of residence and work. Full article

The present study aimed to evaluate the multivariate relationships between variables related to burnout and job stress in healthcare workers, evaluating whether the relationships between these dimensions, the variables related to personal factors (age, seniority of service), and work–family balance factors (overwork related to unused vacation days and accumulated overtime hours) change when the worker is engaged in double-caregiving activities. Indeed, the twofold activities of home caregiving and caring at work might expose workers to challenging situations. To accomplish our aim, we carried out network analyses on data from 466 workers (77.90% females). Participants completed the Link Burnout Questionnaire (LBQ) and the Job Satisfaction Scale (OSI). Contrary to expectations, the variables related to work–life balance played a marginal role with respect to job satisfaction and burnout risk for the whole sample. In addition, no significant differences emerged between workers who reported dual-caregiving tasks compared with those who did not. However, some peculiar aspects of the relationship between burnout and job satisfaction emerged in the two subsamples. The results enable an understanding of the interactions among the assessed variables and allow hypothesizing interventions for the sustainability of the work–life balance in healthcare workers with dual-care tasks. Full article

In this paper, we developed a new standby system that combines a retrial strategy with multiple working vacations, and we performed a dynamic analysis of the system. We investigated its well−posedness and asymptotic behavior using the theory of the $C_0-$semigroup in the functional analysis. First, the corresponding model was transformed into an abstract Cauchy problem in Banach space by introducing the state space, the main operator, and its domain of definition. Second, we demonstrated that the model had a unique non−negative time−dependent solution. Using Greiner’s boundary perturbation idea and the spectral properties of the corresponding operator, the non−negative time−dependent solution strongly converged to its steady−state solution. We also provide numerical examples to illustrate the effect of different parameters on the system’s reliability metrics. Full article

Recent progress has seen multiple Ta₂O₅ polymorphs generated by different synthesis techniques. However, discrepancies arise when these polymorphs are produced in widely varying thermodynamic conditions and characterized using different techniques. This work aimed to characterize and compare Ta₂O₅ particles formed at high and low temperatures using nanosecond pulsed laser ablation (PLA) and continuous wave (CW) laser heating of a local area of tantalum in either air or an ¹⁸O₂ atmosphere. Scanning electron microscopy (SEM) and Raman spectroscopy of the micrometer-sized particles generated by PLA were consistent with either a localized amorphous Ta₂O₅ phase or a similar, but not identical, crystalline β-Ta₂O₅ phase. The Raman spectrum of the material formed at the point of CW laser impingement was in good agreement with the previously established ceramic “H-Ta₂O₅” phase. TEM and electron diffraction analysis of these particles indicated the phase structure matched an oxygen-vacated superstructure of monoclinic H-Ta₂O₅. Further from the point of laser impingement, CW heating produced particles with a Raman spectrum that matched β-Ta₂O₅. We confirmed that the high-temperature ceramic phase characterized in previous work by Raman spectroscopy was the same monoclinic phase characterized in different work by TEM and could be produced by direct laser heating of metal in air. Full article