Search Results (34)

Liquefied natural gas (LNG) is increasingly used in maritime propulsion systems to reduce atmospheric emissions. However, methane slip from dual-fuel engines remains a critical limitation due to the high global warming potential of methane. This study presents a comprehensive experimental assessment of greenhouse gas (GHG) emissions from a new-generation low-pressure four-stroke dual-fuel (LPDF 4-S) engine installed on a cruise vessel and operating on both LNG and marine gas oil (MGO). Measurements were carried out during full-scale sea trials under real navigation conditions. Results show that methane slip remains strongly dependent on engine load, with low and stable values at medium-to-high loads (1.95 g·kWh⁻¹ average over the 60–90% range) and a value of 5.6 g·kWh⁻¹ at 26% engine load. Compared with the previous engine generation (46DF), the 46TS-DF engine exhibits an approximate 18% reduction in methane slip above 60% load. On a well-to-wake basis, this results in an overall carbon dioxide CO₂-equivalent emission reduction of about 6%, of which 42% is attributable to methane slip reduction and the remainder to improved energy efficiency. In contrast, switching from MGO to LNG operation leads to a 21% decrease in CO₂-equivalent emissions. Black carbon (BC) emissions were measured and as expected despite the limited number of available studies, they were found to be significantly lower in LNG mode, with reductions exceeding 90% compared with MGO operation. Finally, an Engine Load Monitoring (ELM) analysis based on one year of operational data highlights the strong influence of vessel operating profiles on methane slip. The application of both International Maritime Organization (IMO) and FuelEU Maritime methodologies yields consistent methane slip coefficients (1.34% and 1.36%, respectively), significantly lower than current default values, noting that these estimates do not include crankcase emissions. These results demonstrate the importance of integrating real operational conditions into emission assessment frameworks for LNG-fuelled vessels. Full article

This paper presents a comprehensive three-dimensional numerical investigation of a novel vertical-axis wind turbine (VAWT) characterised by a unique aerodynamic profile and a passive blade-pitch control mechanism. Unlike conventional fixed-geometry designs, the proposed turbine utilizes rectangular blades mounted on horizontal axes via articulated bearings, allowing them to rotate freely up to 90 degrees, constrained by a vertical pin-and-belt system. This configuration ensures that blades on the power-stroke side hit the vertical stopper to capture maximum wind energy, while blades on the return-stroke side open up to 90 degrees to significantly reduce aerodynamic drag. This dynamic adjustment enables the turbine to operate efficiently in low-wind conditions (3–5 m/s) while maintaining enhanced torque stability. To ensure numerical reliability, a rigorous grid independence study was performed, and the computational domain was configured to eliminate wall interference effects. The aerodynamic performance was analyzed using COMSOL Multiphysics v6.2 by solving the Reynolds-averaged Navier–Stokes (RANS) equations. Four turbulence models—SST, k–ε, k–ω, and RNG—were evaluated, with the SST model demonstrating the highest fidelity in capturing flow separation and wake structures under adverse pressure gradients. This study establishes the turbine’s performance benchmarks, including the power coefficient (C_p) versus tip speed ratio (TSR) curves. The numerical results were validated against laboratory experimental data, with excellent agreement (relative error < 5%). The findings identify the optimal geometric parameters and tangential velocity distributions that distinguish this configuration (Patent FAP 20240465) from traditional VAWTs. Finally, the successful implementation of a 2 kW prototype confirms the model’s accuracy and highlights the turbine’s potential as a stable and efficient solution for sustainable urban energy harvesting. Full article

Honeybee (Apis mellifera) flight and vertical locomotion were investigated using high-speed imaging and schlieren flow visualization. Free-flight recordings were analyzed to extract wingbeat frequency, projected stroke amplitude, wingtip trajectories, and membrane deformation. The wingtip trajectory exhibited a pronounced asymmetry between upstroke and downstroke, suggesting a dominant role of the downstroke in thrust production. Significant membrane deformation was observed near stroke reversal, indicating strong wing flexibility and dynamic modulation of wing shape during flapping. A novel support-based framework was introduced to characterize vertical locomotion through the support polygon formed by leg contact points and the displacement of its centroid relative to the body. This movement function quantified changes in support distribution and revealed adaptive leg-contact strategies during wall climbing. Schlieren visualization provided qualitative evidence of wingtip vortex formation, although finer wake structures remained difficult to resolve. These findings provide new experimental observations of honeybee flight kinematics and introduce a quantitative framework for analyzing vertical locomotion using support redistribution metrics. Full article

Background: High inter-rater variability in DWI-FLAIR mismatch assessments for acute ischemic stroke (AIS) has spurred interest in assisting automated imaging measures. In this study, we explored whether DWI-FLAIR mismatch assessment and automated quantification of FLAIR hyperintensity, DWI-FLAIR volume ratio, and DWI volume could predict changes in NIHSS score following intravenous thrombolysis (IVT) in patients with AIS of unknown time since onset (TSO). We also exploratively compared radiological DWI-FLAIR mismatch assessments and imaging measures between patients who received IVT and those who did not. Methods: We conducted a retrospective, exploratory, single-center study analyzing brain MRIs from a consecutive cohort of patients with suspected AIS and unknown TSO admitted over two years. Patients with DWI hyperintensity lesions related to ischemia, identified automatically and subsequently verified radiologically, were included. We examined the correlation between automated imaging measures, retrospective DWI-FLAIR mismatch assessments, and changes in NIHSS score from baseline to 24 h post-treatment. Results: Of 333 patients included, 109 received IVT (mean age 68.9 ± 15.2 years) and 224 did not (mean age 70.8 ± 13.8 years). The median baseline NIHSS score was 5 in both groups, improving to 2 after IVT. The DWI volume significantly correlated with changes in NIHSS score (p = 0.002); FLAIR intensity demonstrated borderline significance (p = 0.056); and DWI-FLAIR volume ratio showed no statistically significant association in this cohort (p = 0.511). We did not find statistical evidence that the retrospective binary mismatch assessment was correlated with differences in outcome (p > 0.145). Conclusions: This study supports moving beyond binary DWI-FLAIR mismatch, suggesting that continuous, automated imaging parameters could potentially assist the radiologist in AIS management. As evidence remains preliminary, large-scale research is needed to establish clinical utility. Full article

Acute injuries to the central nervous system (CNS) share a rapid disruption of arousal, autonomic stability, and neuroimmune balance. Among the neuromodulatory systems affected, the orexin (hypocretin) network is uniquely positioned at the intersection of wakefulness, autonomic control, and motivated behavior. Experimental evidence across ischemic, hemorrhagic, traumatic, and systemic models shows that orexin signaling is sharply suppressed during the early post-injury collapse and gradually recovers as arousal circuits and homeostatic functions stabilize. Controlled enhancement of orexinergic tone has been found to improve arousal state, modulate inflammatory responses, and support behavioral engagement, although these effects are highly dependent on timing, receptor subtype, and physiological context. This review synthesizes evidence from ischemia, hemorrhagic stroke, traumatic brain and spinal cord injury, and systemic inflammatory states, and examines the conceptual and translational rationale for targeting orexin pathways. We summarize available pharmacological, peptide-based, neuromodulatory, and physiological strategies to boost orexinergic tone, highlighting the growing development of selective OX₂ agonists and experimental approaches to enhance endogenous orexin activity. By integrating findings across etiologies within a timing-aware framework, this review addresses a gap in the current literature, which has largely treated these injuries in isolation. While clinical testing in acute CNS injury has not yet been performed, the mechanistic convergence across etiologies suggests that orexinergic modulation may offer a phase-sensitive means to stabilize arousal and support recovery. Taken together, orexin emerges as a state-dependent integrator whose modulation could complement existing therapies by linking early arousal stabilization with longer-term motivational and functional recovery. Full article

Critically ill patients are predisposed to developing cognitive dysfunction, excessive daytime sleepiness (EDS), and fatigue during their stay in the intensive care unit (ICU). Modafinil, a wakefulness-promoting agent, has demonstrated potential benefits in enhancing alertness, cognitive performance, and activity levels in various clinical populations. The present narrative review aims to systematically evaluate the existing literature regarding the administration of modafinil for the treatment of EDS and fatigue in the ICU context. A comprehensive literature search was performed using the Embase, MEDLINE, Web of Science, and Google Scholar databases, covering publications up to 20 June 2025. Studies investigating the use of modafinil to improve wakefulness in ICU patients were identified. A total of nine relevant studies were included, comprising two randomized controlled trials (RCTs), two case series, and five retrospective cohort studies (n = 950 patients). Four of these studies focused on patients with traumatic brain injury or post-stroke conditions, whereas the remaining studies addressed heterogeneous ICU populations. Preliminary evidence indicates that modafinil may enhance wakefulness in selected critically ill patients and potentially facilitate their participation in rehabilitative interventions, such as physical therapy. Nonetheless, robust conclusions regarding efficacy and safety remain limited by the small sample sizes and methodological constraints of the available studies. Consequently, further large-scale RCTs are warranted to elucidate the therapeutic role of modafinil in the management of EDS and hypoactivity among ICU patients. Full article

Since the earliest investigations into the impact of sleep-related breathing disorders on cardiovascular risk, the association between sleep–wake disorders and major cerebrovascular events has been increasingly and robustly established. Recent international joint statements—endorsed by leading scientific societies (e.g., American Heart Association, American Stroke Association, European Academy of Neurology, European Stroke Organization, European Sleep Research Society, and European Respiratory Society)—represent a milestone in stroke prevention and rehabilitation by formally recognizing sleep disorders as both risk factors for ischemic stroke and determinants of poor short- and long-term outcomes. Nevertheless, despite these strong epidemiological and mechanistic associations, the therapeutic evidence supporting sleep–wake interventions (e.g., positive airway pressure therapy, GABA-receptor agonists, melatonin) for stroke prevention remains limited and requires further validation through well-designed clinical trials. In this perspective article, we review recent advances in understanding the bidirectional relationship between sleep disorders and stroke, discuss the proposed pathophysiological mechanisms underpinning this complex interplay—with particular emphasis on arousal-related activation of the autonomic nervous system—and provide a critical appraisal of current research directions and future perspectives. Finally, we underscore the need for closer collaboration between sleep and stroke specialists to bridge existing knowledge gaps and optimize patient care. Full article

Background: Defined as a self-selected speed of <0.4 m/s, chronic stroke survivors falling in this category are classified as “severe”, usually homebound and sedentary, and they experience worse outcomes. Limited rehabilitation strategies are available to improve walking speed and related outcomes in this subgroup, and questions regarding effective rehabilitation options remain. The objective of this study was to determine the effects of backward (BLTT) and forward (FLTT) locomotor treadmill training on overground walking speed, spatiotemporal symmetry, and dynamic postural stability. Methods: In this single-center, assessor-blinded, randomized controlled pilot trial, 14 stroke survivors with severe waking impairment underwent 12 sessions of BLTT (n = 7) or FLTT (n = 7). The primary outcome was the proportion of participants reaching clinically meaningful important difference (MCID) on the 10-meter walk test following training completion. Secondary outcomes were between-group differences in walking speed, spatiotemporal symmetry, and completion time on the 3-meter timed up and go (3M TUG) at 24 h, 30 days, and 90 days POST. Results: Two subjects in the BLTT group (28.6%) and one (14.3%) in FLTT achieved MCID following training; however, most subjects did not, with significant variability in response. At 24 h POST, the median (IQR) percent change in walking speed was 28.9 (9.01–36.7) and 17.4 (12.6–39.7) with BLTT and FLTT, respectively; however, no between-group differences were seen (p = 0.80) at this time point or at 30 (p > 0.99) and 90 (p > 0.99) days follow up. Likewise, there were no significant between-group differences in spatiotemporal symmetry and the 3M TUG across time points. Conclusions: While preliminary, this study found that 12 training sessions did not lead to group-level achievement of MCID for walking speed in our cohort and found no significant between-group differences in walking capacity or dynamic postural stability. Future well-powered dosing trials and mechanistically driven studies are needed to optimize and identify predictors of training response. Full article

Background/Aim: Currently, there are limited evidence-based protocols for improving upper extremity (UE) motor function after stroke. The Keys protocol, a distributed form of constraint-induced movement therapy (CIMT), delivers CIMT components in fewer hours per day over an extended period, fitting outpatient rehabilitation schedules and third-party payor models. This pilot study aimed to assess the effectiveness of the Keys protocol in enhancing UE capacity and performance poststroke. Methods: Ten adults with chronic stroke (>6 months) participated in an 8-week intervention. The protocol included 22 supervised training sessions (1.5 h each): 4 days/week for 4 weeks, 2 days/week for weeks 5–6, and 1 day/week for weeks 7–8. Participants wore a restraint mitt on the less-affected UE during waking hours and used an adapted transfer package. Outcome measures included the Motor Activity Log (MAL), Wolf Motor Function Test (WMFT), Stroke Impact Scale (SIS), and Zung Depression Scale, assessed pre-treatment, mid-treatment (4 weeks), and posttreatment. Results: Significant improvements were observed in SIS Strength, ADLs/IADLs, Mobility, and Hand Function domains, exceeding MCID thresholds. Memory and Communication domains improved significantly at the 3-month follow-up. WMFT performance times improved, with fewer incomplete tasks. MAL scores for Amount of Use and Quality of Movement increased across all time points. Depressive symptoms significantly decreased posttreatment. Conclusions: The Keys protocol effectively improves UE use, motor function, mood, and quality of life, with the greatest gains observed mid-intervention. These findings support its feasibility and potential for outpatient stroke rehabilitation (ClinicalTrials.gov Registration: NCT05311384). Full article

Ammonia, being 17.6% hydrogen by mass, is regarded as a hydrogen carrier and carbon-free fuel as long as its production methods rely on renewable energy sources. The production and combustion of green ammonia do not generate carbon dioxide, offering a promising avenue for substantial reductions in greenhouse gas (GHG) emissions from a well-to-wake perspective. This paper presents a comprehensive methodology for the development and validation of a thermodynamic model for a two-stroke low-speed marine engine incorporating a hybrid ammonia-diesel diffusion combustion system. The simulation tools are rigorously validated using experimental data obtained during diesel operation. Subsequently, the study explores various aspects of the novel ammonia-diesel combustion system, addressing combustion and emissions characteristics. The investigation incorporates diverse simulation scenarios involving direct fuel injection through dedicated valves into the cylinder head of a six-cylinder, turbocharged compression-ignition engine. The engine features two diesel injection valves, employed to initiate the combustion process, and two ammonia injection valves. Simulation scenarios include variations in the injection timing of the pilot diesel injector and the relative orientation of diesel and ammonia sprays. Case C emerges as the preferred configuration, demonstrating superior metrics in terms of combustion stability, air-fuel mixing, and emissions profile compared to other cases. The results indicate a reduction of CO₂ emissions of approximately 95% in mass compared to the baseline diesel operation. Furthermore, notable reductions in NO_x emissions are observed, preliminarily attributed to the lower flame temperature of ammonia. Despite the appearance of N₂O emissions as a result of ammonia oxidation, the overall potential reduction in GHG emissions, in CO₂-equivalent terms, exceeds 85% at selected operating points. This work contributes valuable insights into the optimization of cleaner propulsion systems for maritime applications, facilitating the industry’s transition toward more sustainable and environmentally friendly practices. Full article

A growing body of literature demonstrates a critical role for sleep in upregulating diverse biological processes related to protein synthesis, immune function, and cellular housekeeping such as intracellular transport and membrane repair. The energy allocation (EA) hypothesis places sleep in a broader context of resource optimization where sleep–wake partitioning of metabolic operations optimizes resource utilization. The EA hypothesis of sleep carries important implications in health, disease, and homeostatic mechanisms. Specifically, conditions that lead to cellular stress, energy constraints or depression of neuronal activity, such as epilepsy, ischemic stroke or cortical spreading depression, are here proposed to follow similar conserved processes that favor sleep. This review examines the role of local mechanisms, including cytokine release or the accumulation of adenosine, in downregulating wakefulness to favoring sleep, loss of functional connectivity and the upregulation sleep-coupled processes that promote survival. Full article

DWI/FLAIR mismatch assessment for ischemic stroke patients shows promising results in determining if patients are eligible for recombinant tissue-type plasminogen activator (r-tPA) treatment. However, the mismatch criteria suffer from two major issues: binary classification of a non-binary problem and the subjectiveness of the assessor. In this article, we present a simple automatic method for segmenting stroke-related parenchymal hyperintensities on FLAIR, allowing for an automatic and continuous DWI/FLAIR mismatch assessment. We further show that our method’s segmentations have comparable inter-rater agreement (DICE 0.820, SD 0.12) compared to that of two neuro-radiologists (DICE 0.856, SD 0.07), that our method appears robust to hyper-parameter choices (suggesting good generalizability), and lastly, that our methods continuous DWI/FLAIR mismatch assessment correlates to mismatch assessments made for a cohort of wake-up stroke patients at hospital submission. The proposed method shows promising results in automating the segmentation of parenchymal hyperintensity within ischemic stroke lesions and could help reduce inter-observer variability of DWI/FLAIR mismatch assessment performed in clinical environments as well as offer a continuous assessment instead of the current binary one. Full article

The thalamus, and its projections to the cerebral cortex, are crucial for regulating sleep rhythms, such as sleep spindles, and for maintaining arousal and sleep homeostasis. Moreover, they play a significant role in memory, executive functioning, and attention. Altered thalamocortical circuitry caused by vascular lesions affects sleep–wake architecture and may contribute to cognitive deficits observed in thalamic stroke patients. This review summarizes the biology of the thalamus and current knowledge regarding the impact of thalamic circuitry on sleep regulation and cognition, drawing from clinical and pre-clinical studies. Furthermore, deep brain stimulation and transcranial magnetic stimulation are discussed as possible therapeutic approaches targeting thalamic circuits. Understanding the role of the thalamus in sleep and cognition opens new avenues for developing novel therapeutic strategies to improve sleep and cognitive functions in affected individuals. Full article

Study objectives: Sleep and circadian rhythms disorders are frequent in the acute stroke. Sleep modifications are likely to contribute to the development of stroke-related delirium, a common neuropsychiatric complication of acute stroke. This systematic review aimed to clarify the association between sleep modifications and the occurrence of delirium in patients with acute stroke. Methods: The current systematic review was performed according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. The search was performed on PubMed and Scopus databases. Only studies that provided data concerning sleep, or pre-existing sleep disorders, in acute stroke and performed a formal evaluation of delirium were included. Results: The literature search enabled the identification of 15 studies, which exhibited high heterogeneity in terms of study design, settings, sleep assessments, delirium measures, and types of sleep intervention. In the study quality assessment, the majority of the studies were rated as weak or moderate. In most of the cases, sleep was subjectively assessed by the patients or rated by clinicians. None of the studies performed polysomnography for the evaluation of sleep. Only four of the studies assessed the impact of a sleep intervention on delirium, suggesting the potentially protective role of sleep promotion in reducing the prevalence and severity of stroke-related delirium. Conclusions: The evidence arising from the present systematic review supports that sleep disruption is a potential promoting factor for stroke-related delirium. We suggest that a formal sleep assessment and sleep promotion should be included in routine stroke care. Full article

This article casts a spotlight on various stages of the entangled history of German Protestantism and psychology from the 16th to the 19th centuries to make visible the hitherto neglected religious past of this discipline and the educational aspirations tied to it. In broad strokes, it retraces how the idea of psychology emerged in the wake of the Reformation and continued to be shaped by German Protestant thinkers for centuries to come. First, the article reconstructs how, after Luther, the term “psychology” came to denote Protestant attempts to construct a non-Catholic scientia de anima. The dissemination and popularization of this endeavor in the writings of German Protestants is discussed in the second section. The third and fourth sections are devoted to shifts in reasoning about the soul during the early German Enlightenment and the subsequent flourishing of attempts at establishing psychology as a scientific discipline in its later stages. Finally, the last section looks at the further “scientification of the soul” during the 19th century, which, as will be argued, was crucial to the constitution of the modern educational field in Germany. Full article