Search Results (261)

Background: Reaction time (RT) is a fundamental measure of information processing speed in cognitive neuroscience and is influenced by both structural and functional brain properties. While prior studies have independently linked white matter microstructure and EEG alpha oscillations to cognitive performance, their joint contribution to distinct aspects of RT remains unclear. This study aims to investigate whether multimodal data can dissociate neural systems underlying cognitive and motor components of processing speed. Methods: We analyzed diffusion tensor imaging, resting-state individual EEG alpha peak frequency (IAF), demographic variables, and behavioral RT measures from a GO/NO-GO paradigm in 24 healthy adults from the Cuban Human Brain Mapping Project. Behavioral metrics included the mean, standard deviation and skewness of reaction times for simple and complex tasks. Sparse multiple canonical correlation analysis was applied to identify multivariate associations across modalities. Results: Two significant latent dimensions were identified. The first dimension linked bilateral fronto-temporal association tracts (SLF, IFOF, UNC) with complex RT performance, reflecting higher-order cognitive processing. The second dimension associated motor and interhemispheric tracts (CGC, CST, ILF, forceps major and minor) with intra-individual asymmetric variability (skewness) across tasks, indicating a motor-execution consistency system. IAF did not significantly contribute to either dimension. Sex showed strong associations with both components. Conclusions: Distinct white matter networks were associated with separable cognitive and motor aspects of processing speed, while resting-state alpha frequency did not show stable contributions with behavioral variability in this sample. IAF showed minimal contribution within the identified sparse multivariate dimensions. These findings highlight the importance of multimodal and multivariate approaches for understanding and potentially disentangling complex brain–behavior relationships. Full article

Narrative extraction algorithms construct storylines by finding coherent paths through document collections. The Narrative Trails algorithm frames this as maximum-capacity path optimization, where path quality depends on a coherence function measuring document relationships. We introduce quantum kernels as coherence functions for narrative extraction—to the best of our knowledge, the first systematic characterisation of quantum kernel methods for storyline extraction—and compare them against classical baselines on two corpora using a multi-seed protocol. The sweep covers 93 method evaluations (54 quantum kernels across three encoder families—R_Y+CNOT-ring, IQP/ZZ-feature-map, and a projected quantum kernel—and 39 classical kernels—cosine, RBF, and the cluster-aware Narrative Trails baseline). On 11,215 human navigation paths from Wikispeedia, evaluation metrics divide into two clusters that disagree with each other: alignment-based metrics (length-normalised DTW and per-step DTW similarity) favour methods that produce long alignment-rich paths, while set-overlap metrics (Jaccard and F1) favour methods that produce shorter paths with higher article overlap. On LLM-judged coherence for Cuban news storylines, evaluated under a 12-method × 5-seed × 30-endpoint-pair × 2-judge design (Claude Sonnet 4.5 and GPT-4o, both at $T=0$ via structured tool calling), the cluster-aware classical baseline is the top method in terms of mean overall coherence; the 5-method quantum-kernel pool and the 7-method classical-kernel pool on matched projection input show no significant differences after Holm correction. Cross-task analysis reveals that LLM coherence rank correlates with alignment-cluster Wikispeedia metrics (Spearman $\rho \approx +0.70$) and anti-correlates with overlap-cluster metrics ($\rho \approx -0.62$). A closed-form theoretical analysis shows that the depth-1 R_Y+CNOT-ring kernel reduces to a classical product-of-cosines kernel order equivalent to RBF, explaining the absence of empirical separation at low depth; deeper encoders break the cancellation but exponentially concentrate kernel values, eroding inter-pair distinguishability. Our results characterise quantum coherence kernels as competitive with classical kernels on the same projected input rather than decisively superior, with the cluster-aware classical baseline retaining a modest advantage attributable to its explicit topical structure. Full article

Cooperatives are key organizational forms for economic and social development; however, the factors shaping their development are often examined in a fragmented manner. This study identifies the main dimensions of cooperative development and tests their interrelationships using structural equation modeling (SEM). Based on a literature review and expert validation, a measurement instrument was developed and applied to 410 members from 82 cooperatives in Cuba between March and July 2025. The model was estimated and validated using confirmatory factor analysis (CFA) and SEM. The findings support an integrated framework in which cooperative values, cooperative principles, organizational objectives, community relations, and the institutional environment jointly explain cooperative development. All hypothesized relationships are positive and statistically significant, with organizational objectives and the institutional environment showing relatively stronger effects compared to normative and relational dimensions. The results demonstrate that cooperative development is a multidimensional and context-dependent process that cannot be explained by normative principles alone. Instead, it depends on the organization’s capacity to translate cooperative identity into strategic objectives and to operate within enabling institutional conditions. The study provides an empirically validated framework for analyzing cooperative governance and offers practical insights for strengthening organizational performance in emerging economies. Full article

This study presents a comprehensive thermo-energetic and exergetic assessment of a 250 MW steam boiler in a Cuban thermal power plant, operating under partial load conditions (plant: 62–66%; boiler: 58–61%). An integrated diagnostic methodology was developed and implemented in Mathcad 15 to evaluate key performance indicators, including thermal efficiency (η_tGV); exergetic efficiency (η_ExGV); exergy destruction ratio (γ_ExGV); steam generation index (IG_v); and specific fuel consumption (B_Esp). The methodology was applied to two fuels with contrasting thermophysical and chemical properties: fuel oil and Enhanced Crude Oil 650. The results indicate superior performance with fuel oil due to its higher heating value; however, efficiency losses were mainly attributed to operational factors such as excessive air supply (22.7–26.4%), heat transfer surface fouling, and inadequate maintenance. The analysis revealed significant deviations from design values—thermal efficiency (90.27–90.59%) and exergetic efficiency (<60%)—highlighting an untapped potential for energy savings. Quantitative estimates indicate potential annual fuel cost savings of approximately 1.2 million USD through optimized combustion and maintenance practices. The proposed framework enables accurate diagnostics of complex boiler systems and provides actionable indicators to support combustion optimization and energy efficiency strategies in conventional thermal power plants. Full article

Pinus caribaea M. comprises three varieties: hondurensis, bahamensis and caribaea, the latter being crucial to the Cuban forestry industry. This systematic review evaluated some physical–mechanical properties and tracheid biometry of Pinus caribaea M. wood, with particular emphasis on var. caribaea, to identify potential knowledge gaps and followed the PRISMA 2020 guidelines. The investigation was conducted in four databases, including gray literature up to December 2024, and the risk of bias was assessed using a tool adapted from the JBI critical appraisal checklist. A total of 535 studies were identified, of which 75 were included in the review based on the inclusion criteria. It was found that only 17.3% of the selected publications focus on var. caribaea. Most studies evaluate physical properties, with less attention paid to mechanical properties and cell biometry. A downward trend in recent publications was noted for this variety, along with a predominance of the radial direction as a source of variation. A lack of research on mature trees (>30 years) as well as other sources of variation were identified as information gaps. Value ranges for density, shrinkage, modulus of elasticity and modulus of rupture in static bending, compressive strength parallel to the grain, as well as tracheid biometry were synthesized from the available publications for all varieties. It is concluded that var. caribaea is under-researched, and a systematic study is therefore required to optimize its use and industrial impact. Full article

Previous studies suggest that elevated competitive anxiety may increase the likelihood of injury. The present research aims to examine the role of competitive anxiety as a predictor of injury occurrence, frequency, and severity. A cross-sectional, correlational design was conducted with 131 athletes (mean age = 16.49 years), predominantly male. Injury data were obtained through medical record review, and competitive anxiety was assessed using the Competitive Anxiety Inventory-2. Empirical frequency distributions, descriptive statistics, non-parametric tests, and logistic and ordinal regression models were employed. A high incidence of injuries was observed, although most were minor. Competitive anxiety was characterized by elevated levels of cognitive anxiety and self-confidence. Injured athletes exhibited greater overall competitive anxiety (r = 0.31, p < 0.001), with higher levels observed among those who sustained more injuries (ε² = 0.12, p = 0.001), and a very large effect was found in relation to injury severity (ε² = 0.17, p < 0.001). The occurrence of injury can only be predicted in 10.9–14.7% of cases through increased cognitive and somatic anxiety, whereas an increase across all dimensions of competitive anxiety predicts a greater number (13–14%) and severity (20.3–21.8%) of injuries. These findings underscore the importance of developing skills to manage competitive anxiety, particularly its cognitive dimension and maintaining optimal levels of self-confidence in young athletes. Full article

Cubane-1,4-dicarboxylic acid is a key intermediate in the synthesis of the Platonic solid, cubane. While cubane has been extensively studied, its precursor has not. Here, we provide a comprehensive characterization of the vibrational spectra (infrared, Raman, inelastic neutron scattering (INS)) of cubane-1,4-dicarboxylic acid and its isotopomer with the acidic hydrogens exchanged for deuterium. In combination with density functional theory studies of the complete unit cell, we show that the dynamics of the carboxylic acid and the cubane core are largely independent; the effect is mostly the result of the increased mass of the substituent at the 1,4 positions: 45 versus 1. The known crystal structure is unusual in that the carboxylic acid is present as two conformers: syn and anti. The calculations show that the in-plane and out-of-plane C–O–H bending modes have different transition energies in the two conformers. For all the other modes, both conformers contribute approximately equally. Full article

The ligand-driven self-assembly of metal clusters offers a powerful strategy for constructing discrete molecular architectures with tunable magnetic and structural properties. By judiciously selecting appropriate multidentate ligands, researchers can direct the formation of polynuclear metal assemblies with diverse nuclearities, geometries, and topologies. Coordination-driven processes commonly stabilize such assemblies where multidentate ligands operate as templates and linkers. These will also determine how the metal centers are arranged in space and how they connect to each other. These clusters can take on shapes that range from basic bridging dimers to more complicated icosahedral and cubane-type motifs. They often have excellent symmetry and strong frameworks. Magnetically, these clusters are a great place to study exchange interactions, spin frustration, and the behavior of single-molecule magnets (SMMs). The magnetic characteristics depend on things like the type of metal ions, the bridging ligands, the overall shape, and the local coordination environment. Interestingly, a large number of ligand-assembled clusters exhibit high spin ground states and slow magnetization relaxation, which makes them attractive options for quantum information storage and molecular spintronic devices. This review connects coordination chemistry, supramolecular design, and molecular magnetism of pyridine–amine–carboxylate frameworks, offering insights into fundamental magnetic phenomena and guiding the development of next-generation functional materials. Continued exploration of ligand frameworks and metal combinations holds the potential to yield novel clusters with enhanced or unprecedented magnetic characteristics. Full article

Cuba is in a unique situation in which it has a large (220,000 managed colonies) and isolated honey bee population due to a 60+ year ban on the importation of bees. Despite this, the ectoparasitic mite Varroa destructor arrived in 1996, and with it came deformed wing virus (DWV). In 2018, an island-wide survey detected varroa and DWV in 91% of colonies. In this study, we conducted a full-virome analysis on some of these samples, along with additional samples collected in 2021. For the first time, we detected two variants of Lake Sinai Virus and confirmed the absence of the normally widespread black queen cell virus in Cuba. We also detected both DWV-A and DWV-B master variants, with DWV-B being the dominant variant. Interestingly, the DWV-B/A recombinant was also detected, indicating that despite Cuba’s isolated nature, the pattern of DWV evolution mirrors that found in the USA and Europe. However, this pattern is not found in neighboring Latin America, China, or Japan, where the DWV-A master variant continues to be dominant. How and why two distinct evolutionary DWV pathways have arisen remain a mystery. Full article

Introduction: Rectal colonization by carbapenemase-producing carbapenem-resistant Enterobacterales (CP-CRE) is a risk factor for subsequent infections, which are associated with high mortality rates. Methods: A cross-sectional study was conducted. Rectal swabs were collected from 297 patients within 48 h of admission to eight high-prevalence CP-CRE hospital departments, with follow-up swabs taken weekly for up to 4 weeks. Species identification, antimicrobial susceptibility testing, and genetic detection of carbapenemases were performed. The genetic relationship among isolates was assessed using ERIC-PCR, combined with epidemiological data, to investigate subsequent infections. Results: Fecal carriage of CP-CRE was detected in 15.5% (46/297) of patients- All carbapenemases were metallo-betalactamases, with dominance of NDM-producing Klebsiella pneumoniae. NDM + VIM-producing Escherichia coli were also detected. Among carriers, 26.1% were colonized by two different CRE species, and 86.9% had a history of prior hospitalization. Molecular analysis revealed clonal expansion, suggesting outbreaks among colonized patients. Additionally, 17.4% (8/46) of colonized patients developed an infection, which was significantly associated with urinary catheter use (p = 0.040), mechanical ventilation (p = 0.044), and surgical procedures (p = 0.040). Conclusions: rectal colonization by CP-CRE in hospitalized patients is a serious epidemiological concern, with evidence of clonal spread and subsequent infection in colonized patients. NDM-producing K. pneumoniae was also predominant, detecting co-production of NDM + VIM in E. coli. These findings underscore the urgent need to implement epidemiological surveillance cultures to improve the prevention and control of CP-CRE infections in Cuban hospitals. Full article

Background/Objectives: Coleus aromaticus (Lamiaceae), also known as Cuban oregano or Indian borage, is a semi-succulent perennial species widely used in traditional medicine for its therapeutic and nutritional properties. While its essential oils and aromatic fraction have been extensively investigated, the characterization of its non-volatile metabolites remains limited. The aim of this study was to explore the chemical composition of fresh leaves with a focus on the non-volatile fraction. Methods: Fresh leaves of C. aromaticus were cryogenically treated with liquid nitrogen, ground, and subjected to three different extraction procedures: hydroalcoholic maceration, ethyl acetate maceration, and liquid–liquid partitioning to obtain a dichloromethane organic phase and a hydroalcoholic phase. Extracts and fractions were analyzed by HPTLC and HPLC for metabolic profiling. In addition, the Bligh–Dyer method was applied to separate polar and non-polar metabolites, which were subsequently characterized using NMR spectroscopy. Results: Chromatographic analyses highlighted the occurrence and distribution of organic acids, polyphenols (notably flavonoids), and proteinogenic amino acids. Spectroscopic data confirmed the presence of diverse polar and non-polar metabolites, providing a more detailed chemical fingerprint of C. aromaticus. This integrated approach broadened the phytochemical profile of the species beyond the well-documented essential oils. Conclusions: The results contribute to a better understanding of the non-volatile metabolites of C. aromaticus, offering novel insights into its chemical diversity. These findings highlight the potential of this plant as a valuable source of bioactive compounds, supporting its future application in nutraceutical and pharmaceutical research. Full article

The commitment to the Sustainable Development Goals and the need for increasing the circularity of industrial processes call for the exploitation of byproducts to generate value-added chemicals in cost- and energy-advantageous processes. In this process simulation-based research, two technologies were evaluated for the synthesis of isoamyl acetate from fusel oil: (A) an indirect process, and (B) a direct process using reactive distillation. Aspen Hysys v14.0 was used for simulation. A sensitivity analysis was performed to identify the influence of operating parameters on product purity, isoamyl acetate recovery and productivity, and energy consumption. Technology B was found to be the most favorable, obtaining 22.27 kg/h of isoamyl acetate with a purity of 98%. The total consumption values of cooling water and heating were 24.33 kW and 24.50 kW, respectively. Based on the best conditions, a technical–economic analysis was performed that demonstrated the viability of the process, obtaining a net present value (NPV) of US$3,587,110/year, an internal rate of return (IRR) of 38.95% and a payback period (PP) of 5.05 years. If acid recirculation is considered in the process, an NPV of US$7,232,950, an IRR of 56.34%, and a PP of 3.56 years are obtained. Full article

Rising temperatures are among the most predictable outcomes of climate change, and cacti are particularly vulnerable at the germination stage. We tested seeds of ten Cuban Leptocereus species from coastal and inland habitats under five temperature regimes to evaluate germination responses, thermal buffering capacity for optimal germination, photoblastic behavior, recovery after heat stress, and seedling vigor. Germination declined sharply with increasing temperature, revealing minimal thermal buffering capacity for optimal germination. All species exhibited positively photoblastic seeds, while recovery and the degree of physiological dormancy varied among taxa. Except for one taxon, most displayed partial dormancy that could stagger germination over time. Seedling vigor was not affected by high temperatures in the same way in all species. Overall, our findings suggest that climate warming will further constrain the germination niche of Leptocereus, underscoring the importance of conservation measures such as ex situ propagation. Full article

Canavalia ensiformis (L.) DC. (Fabaceae) is used in Cuba in soils dedicated to coffee cultivation, contributing to soil nutrition and crop productivity. However, no rhizobial isolates are currently available for inoculating this legume in Chromic Eutric Cambisol soils. The aim of this study was to select rhizobial strains that promote the growth of C. ensiformis in Chromic Eutric Cambisol soils. Nodules were collected from C. ensiformis plants, surface-sterilized, and macerated to isolate potential rhizobia. The isolates were characterized based on cultural, morphological, and biochemical traits, and their symbiotic effectiveness was evaluated through in vitro inoculation assays in Macroptilium atropurpureum (siratro) plants. Inoculation trials were conducted under semi-controlled conditions and in the field between coffee rows. The number and dry weight of effective nodules, number of trifoliate leaves, and shoot dry biomass were measured. Nine bacterial isolates were obtained, grouped into four morphotypes, and assigned as possible members of the families Phyllobacteriaceae, Methylobacteriaceae, or Nitrobacteraceae. Under semi-controlled conditions, inoculation with three isolates increased the number of nodules (by 56–80%), the number of trifoliate leaves (by 20–45%), and shoot biomass (by 10–40%) compared to the non-inoculated treatment. Additionally, one of the isolates increased nodule dry weight by 27%. In the field between coffee row, increases were also observed in the number of trifoliate leaves (by 18–26%) and shoot biomass (by 15–24%). This study supports the selection of efficient rhizobia adapted to the edaphoclimatic conditions of Cuban coffee agroecosystems. Full article

Propolis is an apicultural product known for its antioxidant, antimicrobial and anti-inflammatory properties. However, its composition varies with botanical sources, geography, season and bee species, complicating quality control and creating opportunities for adulteration, such as the addition of poplar bud extracts or non-propolis resins. This review synthesizes the latest primary studies and reviews addressing chemical markers identified through analytical platforms, such as TLC, HPTLC, HPLC, LC-MS, GC-MS, NMR, FTIR and ICP, often integrated with chemometrics and machine learning for authentication and standardization. Marker panels are linked to regional chemotypes, including poplar-type, Brazilian green, red and brown, Cuban variants, and stingless bee propolis. Fraud detection strategies using marker-based screening and spectral pattern recognition are also summarized. Multi-marker and chemometric approaches consistently differentiate botanical types, origins and commercial extracts. Common marker families include flavonoids (pinocembrin, chrysin, galangin), phenolic esters (CAPE, benzyl/allyl caffeates), prenylated cinnamates like artepillin C, lignans, and volatile terpenoids or benzenoids. Rapid screening by ATR-FTIR and NMR is often complemented with LC-MS for confirmatory quantitation. Propolis quality control is moving toward harmonized workflows combining FTIR/NMR/HPTLC screening with LC-MS verification and optional elemental or volatile profiling, paving the way for shared marker sets and international standards similar to those for honey. Full article