Search Results (164)

Selective laser melting (SLM) is a 3D printing technology for precision manufacturing. Owing to its high forming accuracy, parts fabricated by SLM can often be used directly without secondary machining. Consequently, the stress field in the structure, especially local stress concentration in small regions, is of great importance. Building on our previous work, this study proposes an accurate and efficient thermo-mechanical analysis method that combines a computational fluid dynamics (CFD) model and a finite element method (FEM) model for stress prediction in micrometer-scale SLM. Compared with the conventional element birth–death method, the present model more faithfully reproduces the SLM process and the post-solidification morphology and stress distribution. Numerical simulation of a single-track TC4 scan shows that pronounced surface undulations and lack-of-fusion regions exhibit significant stress concentration: the local residual stress can reach approximately 900 MPa, whereas regions with relatively smooth surface geometry exhibit stresses of about 650 MPa. This indicates a clear positive correlation between surface quality and stress concentration. The results provide a new theoretical basis for understanding defect formation mechanisms, spatial stress distribution, and scan-path optimization in SLM components. Full article

In the history of Turkish-Islamic culture, every stage of human life—from birth to death—has been ritualized with profound symbolic and spiritual meanings. Turkish religious music has functioned as a fundamental element in these transitional phases, possessing both aesthetic and devotional dimensions. In individual rites of passage such as naming, circumcision, beginning school, and marriage, as well as in collective rituals such as bidding farewell to and welcoming Hajj pilgrims or observing religious days and nights, Turkish religious music has held a significant place. Confronting death—an inevitable and sorrowful reality of life—Turkish society has employed religious music as a consolatory and spiritually guiding medium, transforming it into a ritual mode of expression intended to soften the disruptive impact of death and to give meaning to the mourning process. Sufi order funerals represent one of the manifestations of this aesthetic depth. In this context, (Janāza) funeral ceremonies are not merely occasions of farewell but also rites of metaphysical acceptance and surrender. Since death is considered not an end but “wuṣlat,” that is, reunion with the Absolute Truth (al-Ḥaqq), within Sufi thought, the funeral rites of Sufi orders have been shaped accordingly. In Mawlawī, Bektāshī, Jarrahī, and Rifāʿī orders, not only the canonical funeral prayer (ṣalāt al-janāza) but also various forms of religious music are performed, imparting both aesthetic and spiritual depth to the ceremony. This study aims to examine the religious musical practices present in the funeral ceremonies of these four major Sufi orders, all of which have historically maintained a close relationship with music. A qualitative ritual-musicological approach has been adopted; semi-structured interviews were conducted with the Shaykh of the Rifāʿī order, the Zakirbaşı of the Jarrahī branch of the Khalwatī order, and a Dede of the Bektāshī order. The data sources of the study consist of interview materials, archival-based works, literature on the history of Sufism, sources on Turkish religious music, and digital recordings of Sufi orders’ funeral rituals. The limited number of interviews were analyzed through thematic analysis, while textual analysis and contextual interpretation were employed to examine in detail “the musical forms, thematic structures, performance contexts, and symbolic functions” present in these rituals. Preliminary findings indicate that the music unique to Sufi order funerals fulfills multiple functions, including “spiritual consolation, strengthening social solidarity, doctrinal expression of belief in the afterlife, and transforming mourning into a sacred experience.” The funeral traditions of the four orders examined possess distinctive musical structures, and these structures constitute an identifiable aesthetic form within the Ottoman and Turkish religious-musical tradition. It has also been determined that the repertory performed in Sufi orders’ funeral ceremonies is largely rooted in the tekke (Sufi lodge) musical tradition and that various forms of Turkish religious music are prominently represented in these rituals. This study has brought to light the religious musical repertory performed within the funeral rituals of Sufi orders—an area that has remained insufficiently explored to date—and has demonstrated that this repertory exerts positive psychosocial effects on both Sufi adherents and other participants in their approach to death. In this respect, the study sheds light on the repertory of Turkish religious music and offers an original contribution to the scholarly literature. Full article

This paper proposes an evolutionary modeling method of scattering clusters based on Geometric-Based Stochastic Modeling (GBSM). In the single-bounce scenario of vacuum pipeline maglev train communication, the dynamic generation and extinction process and statistical behavior of multiple clusters at high speed are analyzed. The model abstracts the multipath component into a cluster structure. By iteratively updating the channel state and the birth and death cluster information after initialization, a dynamic model of the evolution process of scattering clusters in time-varying channels is constructed, which depicts the time evolution process of multipath clusters. Under the framework of GBSM, the correlation statistical characteristics of the scattering cluster birth and death process are further derived, and analytical integral form expression of the channel time autocorrelation function (ACF) is theoretically solved. The simulation results reveal the inherent law of channel time-varying characteristics under the joint action of high-speed train operation and closed pipe structure, and the results show that the proposed method can effectively capture the transient dynamic characteristics and long-term statistical trends of multipath clusters. The proposed model provides a practical basis for channel modeling in vacuum tube maglev wireless communication systems. Full article

Orthotropic steel decks (OSDs) serve as critical load-bearing components in long-span steel bridges, but high-amplitude welding residual stresses (WRSs) generated during the welding process pose significant threats to structural integrity. To mitigate these stresses, post-weld heat treatment (PWHT) has emerged as a promising technique. This investigation first establishes a semi-structural thermo-elasto-plastic finite element model of the Deck-U-rib-Diaphragm system with a six-pass welding sequence. The temperature field is modeled via a double-ellipsoidal heat source and birth–death element approach. Subsequently, thermo-mechanical coupling analysis is conducted to investigate the distribution characteristics of Von Mises residual stresses. The stress relief effect of PWHT is then explored by comparing different holding temperatures (T) and holding times (t), achieving a balance between stress reduction effectiveness and economic efficiency, when T = 550 °C and t = 40 min. Finally, full-scale experimental tests are designed, and the hole-drilling method is utilized to validate the numerical simulation results. This research provides valuable insights for the design of PWHT processes for OSDs. Full article

Heterotrimeric G_i proteins are crucial modulators of G protein-coupled receptor signaling, with Gα_i2 ubiquitously expressed and implicated in diverse physiological processes. Previous reports described partial lethality in Gnai2-deficient mice, but the timing and mechanism of death remained unclear. Here, we demonstrate that impaired neonatal respiratory adaptation contributes to mortality in Gnai2-deficient neonates. Despite normal Mendelian distribution at birth and no overt malformations, at least 20% of the expected Gnai2-deficient neonates died within minutes after birth, displaying abnormal breathing, cyanosis, and features resembling neonatal respiratory distress syndrome (RDS). Histological and ultrastructural analyses revealed reduced alveolar surface area, thickened septa, increased mesenchymal tissue, and impaired surfactant ultrastructure, despite unaltered alveolar surfactant phospholipid levels. These findings suggest that Gα_i2 modulates the structural deployment and functional organization of surfactant within alveoli, although the incomplete phenotype and survival of some neonates indicate a regulatory rather than indispensable role of Gα_i2. Our data underscore the complexity of neonatal respiratory adaptation and highlight potential systemic and intercellular mechanisms underlying alveolar stabilization. Full article

During the Fused Deposition Modeling (FDM) molding process, temperature changes are nonlinear and instantaneous, which is a key parameter affecting FDM printing efficiency, molding accuracy, warpage deformation, and other factors. This study presents a finite element simulation framework that integrates ANSYS Parametric Design Language (APDL) with birth–death element technology to investigate the temperature evolution and thermomechanical behavior during the FDM process. The framework enables dynamic simulation of the complete printing and cooling cycle, capturing the layer-by-layer material deposition and subsequent thermal history. Results indicate that temperature distribution follows a gradient pattern along the printing path, with rapid heat dissipation at the periphery and heat accumulation in the central regions. Thermomechanical coupling analysis reveals significant stress concentration at the part bottom (310 MPa) and progressive strain increase from bottom (3.68 × 10⁻⁵ m) to top (2.95 × 10⁻⁴ m). Experimental validation demonstrates strong agreement with numerical predictions, showing maximum temperature deviations below 8% and strain distribution errors within 5%. This integrated approach provides an effective tool for predicting thermal-induced deformations and optimizing FDM process parameters to enhance part quality. Full article

Background/Objectives: The mutational dynamics of microsatellites over deep evolutionary timescales are poorly understood. This study aims to elucidate the life history of trinucleotide microsatellites by tracing orthologous loci across divergent vertebrate lineages and characterizing their mutational pathways. Methods: We developed a bioinformatic framework for identifying orthologous microsatellite loci using conserved flanking sequences. This approach was applied to three trinucleotide microsatellites located in exonic, intronic, and intergenic regions, respectively. These loci were amplified and sequenced across 126 individuals representing 64 vertebrate species, whose divergence times range from 6 to 150 million years ago (MYA). Results: Flanking sequences proved essential for reliable orthology assignment, while repeat motifs revealed distinct mutational pathways. Microsatellite decay occurs through two primary mechanisms: the complete loss of dominant repeats or their progressive reduction to solitary units (≤1 repeat). This degeneration process is facilitated by cryptic simple sequences (CSS), which act as genomic catalysts promoting birth–death transitions. Large intra-motif deletions were identified as the key mutational event driving contractions and eventual locus degeneration. Furthermore, mutational patterns were highly locus-specific, influenced by genomic context. Conclusions: Although the study focused on only three loci, limiting broader generalizations, our findings provide mechanistic insights into microsatellite evolution. These results establish a foundation for modeling complex microsatellite life histories and highlight the role of CSS in facilitating evolutionary turnover. Full article

Cannabis is one of the most studied psychoactive substances due to its increasing prevalence and evolving legal status. Of particular concern is the rising consumption among young individuals, where excessive use may disrupt reproductive processes and pose long-term health risks to offspring. This narrative review examines the effects of cannabis use on male and female reproductive health, including its impact on male fertility, the female reproductive system, placental function, and prenatal and postnatal outcomes, as well as fetal development. A nonsystematic review was conducted using PubMed, Scopus, Web of Science, and Google Scholar databases in November 2024. After screening titles and abstracts and the full-text analysis, 64 studies were included in this narrative review. In men, cannabinoids can interfere with spermatogenesis, reduce sperm motility and quality, and lower testosterone levels, as demonstrated in clinical and experimental studies. In women, cannabinoid-induced disorders include negative effects on ovarian follicle maturation, ovulation, placental function, and prenatal development. Prenatal exposure to cannabis is associated with the risk of reduced birth weight, birth defects, sudden infant death syndrome (SIDS) or lactation problems due to the penetration of cannabis metabolites into breast milk. The findings highlight the potential negative effects of cannabis on reproductive health and fetal development. Given these risks, individuals attempting to conceive, and pregnant women should be advised against cannabis use. Greater awareness is needed among healthcare professionals and the public regarding the reproductive risks associated with cannabis consumption. While the evidence on teratogenic effects is not always conclusive, caution should be exercised, and further research is essential to deepen the understanding of these effects. 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

Introduction: Fetal Inflammatory Response Syndrome (FIRS) is widely acknowledged for its contribution to neonatal morbidity in premature infants. Being a systemic inflammatory process triggered by intrauterine infections or other stimuli, FIRS has gained significant attention due to its complex implications for neonatal adverse outcomes: preterm birth, early onset neonatal sepsis, death or long-term neurodevelopmental impairments. Fetal plasma Interleukin-6 (IL-6) levels above 11 pg/mL define FIRS and serve as an essential biomarker, providing insights into the complex mechanisms underlying this response. This study aims to evaluate the clinical, laboratory, and therapeutic differences between preterm neonates with and without FIRS. Methods: A prospective cohort study was conducted, involving 125 preterm neonates with gestational ages between 23 and 37 weeks, who were admitted to the Neonatal Intensive Care Unit (NICU) at the Emergency University Hospital Bucharest between April 2023 and April 2025. Infants were stratified into FIRS and non-FIRS groups based on the measurement of cord blood IL-6 levels greater than 11 pg/mL. Demographic, biochemical, and therapeutic parameters were compared across the two groups. Results: Preterm neonates with FIRS had significantly lower birth weight, length, and head circumference, and lower Apgar scores at 1 and 5 min (p = 0.001). FIRS was associated with a higher incidence of vaginal delivery, meconium-stained amniotic fluid, and neonatal metabolic imbalances, requiring more respiratory support, longer antibiotic treatment periods, and more blood transfusions (p < 0.05). Neonatal complications such as early-onset sepsis (EOS) and late-onset sepsis (LOS), respiratory distress, necrotizing enterocolitis (NEC), intraventricular hemorrhage (IVH), and retinopathy of prematurity (ROP) were significantly more frequent in the FIRS group (p ≤ 0.01). Among maternal cervical screening, Chlamydia trachomatis was the only pathogen significantly associated with FIRS. Conclusions: FIRS in preterm neonates is linked to important perinatal inflammation, adverse short and long-term outcomes, and extensive medical intervention. These findings highlight the value of early identification of intrauterine inflammation and targeted neonatal monitoring strategies. Further studies are needed to explore long-term outcomes and improve diagnostic and therapeutic protocols. Full article

To address the increasing demand for computational and communication resources, modern networked systems often rely on heterogeneous servers, including those requiring setup times, such as virtual machines or servers, and others that are always active. In this paper, we model and analyze the performance of such hybrid systems using a level-dependent quasi-birth-and-death (LDQBD) process. Building upon an existing queueing model, we extend the analysis by considering scalable approximation methods. Since matrix analytic methods become computationally expensive in large-scale settings, we propose a stochastic bounding approach that derives upper and lower bounds for the stationary distribution, thereby significantly reducing computational cost. This approach further provides bounds on the performance metrics of the hybrid system. Full article

This study applies stochastic discrete event modeling to demonstrate that reducing wait times for specialized outpatient clinics in the Costa Rican public healthcare system is possible. The classification process identified four medical specialties with the longest wait times. It includes the creation of a separate queuing theory model for each specialty. The birth and death model allowed for estimating the number of arrivals and consultations in the simulation. Validation was performed by comparing the model’s input and output data with real-world statistical reports. An analysis of medical specialists revealed that approximately 22% of patients referred to secondary care did not require specialized medical consultation. Through simulation and the use of stochastic input data, patient waiting times decreased. In an optimistic scenario, waiting times decreased steadily across all specialties over 24 months. Ophthalmology and orthopedics reduced their waiting times to less than 300 days. Otorhinolaryngology decreased from 370 to 250 days, and urology showed the most significant improvement, decreasing from 350 to 100 days in the first year and remaining stable. This evidence transforms the traditional paradigm of increasing capacity as the only solution to the waiting list problem and positions improving the referral process as an alternative. To achieve these results, the study highlights the importance of implementing improved triage protocols in primary care, integrating decision-support tools for general practitioners using machine learning, for example, to reduce unnecessary referrals. Training programs and feedback mechanisms could also align referral practices with specialty criteria. While these strategies were not implemented in this study, the simulation results provide a solid basis for their design and future evaluation. Full article

Neonatal calves possess an immature and naïve immune system and are reliant on the intake of maternal colostrum for the passive transfer of immunoglobulins. Maternal antibodies delivered to the calf via colostrum, are crucial to prevent calfhood diseases and death. Failure of transfer of passive immunity (FTPI) is a condition in which calves do not acquire enough maternal antibodies, mostly in the form of IgG, due to inadequate colostrum quality or delayed colostrum feeding. The diagnosis and risk factors for FTPI have been widely studied in dairy cattle; however, in beef calves, the research interest in the topic is relatively recent, and the most adequate diagnostic and preventative methods are still in development, making it difficult to define recommendations for the assessment and prevention of FTPI in cow–calf operations. The objective of this scoping review is to identify the published literature on best practices for colostrum management and transfer of passive immunity (TPI) in neonatal beef calves. The literature was searched using three electronic databases (CAB Direct, Scopus, and PubMed) for publications from 2003 to 2025. The search process was performed during the period from May to July 2023, and was repeated in January 2025. All screening processes were performed using Covidence systematic review software (Veritas Health Innovation, Melbourne, Australia). A total of 800 studies were initially identified through database searches. After removing duplicates, 346 studies were screened based on their titles and abstracts, leading to the exclusion of 260 studies. The remaining 86 studies underwent full-text screening, and 58 studies were considered eligible for data extraction. Hand-searching the references from published review papers on the subject yielded an additional five studies, bringing the total to 63 included articles. The prevalence of FTPI has been estimated to be between 5.8% and 34.5% in beef calves. Factors studied related to colostrum management include quality and quantity of colostrum intake, the timing and method of colostrum feeding, and the microbial content of the colostrum. Studies on risk factors related to the calf include the topics calf sex, twin status, calf vigor, weight, month of birth, cortisol and epinephrine concentrations, and the administration of nonsteroidal anti-inflammatory drugs to calves after difficult calving. The dam-related risk factors studied include dam body condition score and udder conformation, breed, parity, genetics, prepartum vaccinations and nutrition, calving area and difficulty, and the administration of nonsteroidal anti-inflammatory drugs at C-section. Most importantly for beef systems, calves with low vigor and a weak suckling reflex are at high risk for FTPI; therefore, these calves should be given extra attention to ensure an adequate consumption of colostrum. While serum IgG levels of < 8 g/L or < 10 g/L have been suggested as cutoffs for the diagnosis of FTPI, 16 g/L and 24 g/L have emerged as cutoffs for adequate and optimal serum IgG levels in beef calves. Several field-ready diagnostics have been compared in various studies to the reference standards for measuring indicators of TPI in beef calves, where results often differ between models or manufacturers. Therefore, care must be taken when interpreting these results. Full article

Consanguinity is the marriage of two related persons. This type of marriage is one of the main pillars when it comes to recessive hereditary diseases, birth defects, infertility, miscarriages, abortion, and infant deaths. Intermarriage continues to be a common practice in various communities in North Africa, the Middle East, and West and South Asia, as well as among migrants from Europe and North America, even though in more and more countries it has become illegal. Even if security and stability are some of the motivations for consanguineous marriage, studies show that women often suffer physical and verbal abuse from their husbands. However, because of the blood bond, tolerance for these habits is much higher. In addition, it seems that the divorce rate is much lower because separation would affect the entire state of the family. The choice of partner is significantly influenced by variables such as limited access to education and financial resources. Illiterate people coming from poor rural areas are much more likely to choose consanguineous marriage to maintain wealth in the family. The lack of medical knowledge about the negative effects of consanguinity leads to an increased rate of abortions, infant deaths, and births of children with congenital birth defects. Today, because of the process of urbanization and increased levels of knowledge, the younger generation is becoming increasingly less receptive to this particular form of marriage. In addition, as education has become more accessible to women, they have become more independent and eager to fulfill their own goals and not the wishes of the family. In conclusion, contrary to the many apparent advantages of consanguineous marriage, partners should put genetic risks first, as medical problems bring with them increased costs in the medical system and also within the family, leading to even lower economic status and consequently perpetuation of this type of marriage. Full article

An $MAP/PH/N$-type queuing system functioning within a finite-state Markovian random environment is studied. The random environment’s state impacts the number of available servers, the underlying processes of customer arrivals and service, and the impatience rate of customers. The impact on the state space of the underlying processes of customer arrivals and of the more general, as compared to exponential, service time distribution defines the novelty of the model. The behavior of the system is described by a multidimensional Markov chain that belongs to the classes of the level-independent quasi-birth-and-death processes or asymptotically quasi-Toeplitz Markov chains, depending on whether or not the customers are absolutely patient in all states of the random environment or are impatient in at least one state of the random environment. Using the tools of the corresponding processes or chains, a stationary analysis of the system is implemented. In particular, it is shown that the system is always ergodic if customers are impatient in at least one state of the random environment. Expressions for the computation of the basic performance measures of the system are presented. Examples of their computation for the system with three states of the random environment are presented as 3-D surfaces. The results can be useful for the analysis of a variety of real-world systems with parameters that may randomly change during system operation. In particular, they can be used for optimally matching the number of active servers and the bandwidth used by the transmission channels to the current rate of arrivals, and vice versa. Full article