Search Results (388)

We develop a matrix-theoretic framework for the natural embedding of the exceptional Lie algebra ${\mathfrak{g}}_2=\mathrm{Der}\left(\mathbb{O}\right)$ in $\mathfrak{so}\left(8\right)$, use it to make constructive a recent existence result on octonionic triality, and derive geometric applications for moduli spaces of principal bundles. Specifically, the derivation condition for $\widehat{D}\in \mathfrak{so}\left(7\right)$ is reformulated as a homogeneous linear system in the 21 entries of $\widehat{D}$, whose solution space is identified with ${\mathfrak{g}}_2=ker\mathsf{\Psi }$, where $\mathsf{\Psi }:\mathfrak{so}\left(7\right)\to {\Lambda }^3{\left({\mathbb{R}}^7\right)}^{*}$ is the Lie derivative with respect to the associative 3-form $\phi$ on $\mathrm{Im}\left(\mathbb{O}\right)$. It is proved that $\mathrm{rank}\mathsf{\Psi }=7$, and an algorithm is given for computing an orthonormal basis of ${\mathfrak{g}}_2$. The image $\mathsf{\Psi }\left({\widehat{A}}_{\sigma }\right)$ of the triality generator is computed for all triples, yielding six nonzero components and squared norm 12. As geometric applications, the map $\mathsf{\Psi }$ is globalized to a morphism of adjoint bundles, giving an intrinsic characterization of the $G_2$-reductible locus in $\mathcal{M}\left(\mathrm{SO}\right(7\left)\right)$. The orthogonal decomposition of $\mathfrak{so}\left(8\right)$ globalizes to an explicit splitting of the adjoint bundle of any $\mathrm{SO}\left(8\right)$-principal bundle admitting a $G_2$-reduction. Finally, $\mathcal{M}\left(G_2\right)$ is identified as a connected component of the triality fixed-point locus in $\mathcal{M}\left(\mathrm{Spin}\right(8\left)\right)$, with an explicit description of the tangent and normal spaces in terms of the Lie-algebraic decomposition. Full article

Small heat shock proteins (sHSPs) serve as “first aid” stress-response proteins in both eukaryotes and prokaryotes. Their holdase activity enables binding to partially denatured proteins, maintaining them in a folding-competent state under stress. The sHSP IbpA from the mycoplasma Acholeplasma laidlawii is a unique member of its family, combining the functions of two Escherichia coli sHSPs that typically act in tandem. In this study, we demonstrate for the first time that IbpA forms distinct supramolecular structures under contrasting temperature stresses in crowded environments without any artificial truncations or mutations at the protein termini. Upon cooling, IbpA in vitro forms long fibril bundles, whereas heating induces the formation of large, rounded agglomerates. At the temperature optimal for culture growth, the protein exists as a mixture of short fibrils and small globules, with the latter predominating. IbpA’s cellular localization mirrors in vitro properties, with an increased proportion of surface-associated proteins among the sHSP partners during cold shock. We also report, for the first time, a rapid and reversible transition of IbpA to a fibrillar form in response to cold. We propose hypotheses regarding potential roles of IbpA in the mycoplasma cell. IbpA from A. laidlawii appears to act as a “molecular equilibrist,” protecting the cell against damage under opposing stresses, though the precise mechanism of its action during cold shock remains to be elucidated. Full article

Let X be a compact connected Riemann surface of genus $g\ge 2$ and let E be a holomorphic vector bundle of rank n over X. The compactness and connectedness of X imply that the characteristic polynomial of any holomorphic endomorphism $\phi \in H^0(X,\mathcal{E}nd\left(E\right))$ has constant coefficients, a fact we call the Principle of Spectral Constancy. As a consequence, the eigenvalues of $\phi$ are globally constant over X, the primary decomposition of E with respect to $\phi$ consists of globally defined holomorphic subbundles, and the Jordan decomposition $\phi ={\phi }_s+{\phi }_n$ into semisimple and nilpotent parts is globally well defined as a decomposition of sections of $\mathcal{E}nd\left(E\right)$. This paper provides a systematic analysis of Jordan normal forms for endomorphisms of holomorphic vector bundles over X, relating the Jordan type of $\phi$ to the stability properties of E. In particular, it is proved that endomorphisms of stable bundles are necessarily scalar, that the Jordan decomposition of an endomorphism of a polystable bundle is determined componentwise by the classical Jordan normal forms of matrices in the associated endomorphism algebra, and that finite-order endomorphisms are always semisimple. These results are applied to the study of fixed points of automorphisms of the moduli space ${\mathcal{B}}_X\left(\mathrm{SL}(n,\mathbb{C})\right)$ of rank n and trivial determinant polystable vector bundles over X. Specifically, a new result establishes that the commutative subalgebra of $H^0(X,\mathcal{E}nd\left(E\right))$ generated by the endomorphism associated with a fixed-point condition is semisimple, so nilpotent endomorphisms of E are precisely those incompatible with the fixed-point structure. Full article

In this paper, we investigate Chen’s $\delta$-invariant for partially slant (PS) submanifolds of complex space forms. A PS-submanifold admits an orthogonal decomposition of the tangent bundle into a proper slant distribution and an arbitrary ambiguous distribution. Using the Gauss equation together with algebraic optimization techniques, we derive a Chen-type inequality relating the $\delta$-invariant to the squared mean curvature, the holomorphic sectional curvature of the ambient space, and the slant angle of the slant distribution. Unlike the classical Chen inequality for slant submanifolds, the obtained estimate contains an additional term reflecting the contribution of the ambiguous distribution. Several corollaries are derived, including dimension-dependent bounds and special cases corresponding to hemi-slant and semi-slant submanifolds. The equality case is also characterized in terms of the structure of the shape operators. These results provide a natural extension of Chen-type inequalities to the broader framework of partially slant geometry in Kähler manifolds. Full article

Shell-and-tube heat exchangers are critical components in oil refining, where their thermal and operational performance is strongly affected by fouling, corrosion-related deterioration, and deposit accumulation in tube-bundle cavities. This study investigates the technical condition of selected TK-type heat exchangers used in refinery services and proposes an integrated maintenance-oriented approach for the assessment and removal of severe deposits formed between tubes. The work first classifies heat-exchanger damage into structural and technological categories, emphasizing fouling as a key source of thermal performance degradation and operational inefficiency. A physical interpretation of compacted deposits is then combined with dynamic modeling to evaluate the response of the pollutant medium to pneumoshock excitation. Based on the analytical and simulation results, the main practical outcome of the study is the development of a pneumoshock cleaning device (PCD) for the mechanical removal of deposits from narrow inter-tube spaces. The proposed approach supports a more effective diagnosis of exchanger condition, helps identify suitable cleaning actions for heavily fouled bundles, and contributes to improved maintenance decision-making in refinery thermal systems, although quantitative before-and-after thermal performance validation is beyond the scope of the present study. As an applied developmental study, the work highlights the relevance of fouling-aware inspection and targeted cleaning technologies for extending equipment serviceability and supporting more reliable thermal management in industrial heat-exchange applications. Full article

Kappa-carrageenan (κ-CRG) forms thermo-reversible physical hydrogels via a coil–helix transition and helix bundling, but its sulfate-driven electrostatic repulsion limits mechanical robustness and control over aqueous disintegration. Here, we show that plant-derived polyphenols reprogram κ-CRG gel through sulfate-directed binding in a structure-dependent manner. Tannic acid (TA) selectively engages κ-CRG sulfate groups, yielding transparent gels and a >5-fold increase in storage modulus, whereas the same TA triggers turbidity and precipitation in sulfate-free agarose, supporting sulfate-mediated specificity. Using monomeric pyrogallol as a galloyl analogue, we demonstrate that monovalent interactions partially reinforce κ-CRG but lack cooperative stabilization. Intervention timing further separates mechanism. Pyrogallol produces pathway-dependent mechanics and gelation temperature, while TA is stage-insensitive, consistent with multivalent network annealing. In simulated gastric/intestinal fluids, pyrogallol/κ-CRG gels retain morphology longer, whereas TA/κ-CRG ones disintegrate rapidly yet exhibit strong adhesion to rough substrates and human skin. These findings provide a fully food-grade route to tune κ-CRG mechanics, thermal behavior, adhesion and programmed disintegration. Full article

Introduction: Work engagement among nurse case managers is central to safe, efficient, person-centred care, yet organisational and team-level factors that support engagement or mitigate burnout remain poorly synthesised. Aim: To map organisational and team-level strategies that enhance work engagement or reduce burnout among nurse case managers and aligned roles, as well as to consider their applicability to Gulf health systems. Method: We conducted a scoping review in accordance with the Arksey and O’Malley framework as refined by Levac et al. and reported it in line with PRISMA-ScR and PRISMA-S guidance. Six databases and targeted sources were searched for English-language records published between 2015 and 2025. Two reviewers independently screened titles/abstracts and full texts against predefined eligibility criteria, charted data using a piloted form, and synthesised findings thematically against Job Demands–Resources (JD-R) domains. Results: Of 303 records identified, 248 were screened after deduplication, and 11 studies were included. Across nine health systems, findings were mapped to three JD-R domains: job resources, job demands, and personal resources. The most recurrent resource-related strategies involved structural supports, staffing stability, coordination infrastructure, and supportive leadership or team practices. Key demands included role complexity, high caseloads, coordination workload, discharge pressures, and staffing instability. Personal-resource approaches were fewer and mainly involved stress management, communication, and reflective practice interventions. Engagement was infrequently measured directly, and only one empirical intervention study originated from a Gulf health system. Conclusions: This JD-R-informed scoping review suggests that strengthening structural, staffing, and coordination resources, alongside supportive leadership and team climates, may be important for sustaining engagement and limiting burnout among nurse case managers. However, these findings should be interpreted as exploratory signals that map the current evidence landscape rather than definitive evidence of effectiveness. Multi-component JD-R-informed bundles in Gulf region health systems should therefore be prioritised for context-sensitive co-design, piloting, and evaluation. Full article

Spatial confinement strongly affects matter by altering structural stability, relaxation times, and equilibrium properties. Interest in hydrogen storage within carbon nanotube bundles has grown because it addresses practical energy needs while revealing rich confined-fluid physics. Understanding how geometry and defects influence hydrogen structure and dynamics is essential to the development of effective storage materials. Here, we investigate how confinement in single-walled carbon nanotube (SWCNT) bundles with vacancies alters the spatial distribution and phase behavior of physisorbed hydrogen. At low temperature, hydrogen forms solid-like, cylindrical layered structures both inside and outside the tubes. Raising the temperature broadens these layers and produces a liquid-like arrangement within the confined regions. This confined solid-to-liquid crossover controls storage capacity and release behavior and can be tuned by temperature, confinement dimensions, and vacancy defects. Full article

To address the low efficiency of finite element modeling and the reliance on manual measurements in electric/magnetic field analysis of complex overhead transmission line structures, this paper develops an IronPython-based automated computational platform within ANSYS Maxwell for 3-D modeling and electric/magnetic field analysis. First, by parsing transmission line data from the Grid Information Model (GIM), a unified coordinate transformation method is proposed to convert geographical coordinates into three-dimensional (3-D) Cartesian coordinates for finite element analysis. Based on the extracted line parameters, conductor sag is calculated and catenary modeling is implemented. An equivalent radius method is also introduced to simplify multi-bundle conductor modeling, enabling fast parametric construction of complex 3-D transmission line models. Second, by combining the IronPython scripting language with the .NET Windows Forms control library, a visualized finite element modeling and computation platform is developed. Finally, a typical double-circuit transmission line on the same tower is taken as a case study to calculate the spatial distribution of electric/magnetic fields. The influence of solution domain size on electric/magnetic field computation results is investigated, and optimal solution domain parameters are determined. The finite element results generated by the developed platform are further validated through comparison with measured data. The results demonstrate good agreement between calculated and measured values, confirming the accuracy and engineering applicability of the developed platform for electric/magnetic environment analysis of overhead transmission lines. Full article

Background: Resynchronization therapy has become a cornerstone in patients with heart failure (HF). Recent advancements in this field have led to the development of the so-called “left bundle branch area pacing” (LBBAP), a form of pacing where a single ventricular catheter directly addresses the left bundle for a more physiological stimulation. The current literature provides encouraging evidence regarding this topic, but there is still limited data for the older population, particularly those aged ≥75 years. This review aims to clarify how LBBAP has been explored in this cohort and if its application could be safe and effective even in the most advanced stages of life. Methods: A search of articles from PubMed was conducted. Patients were considered older if above 75 years of age. Data regarding Italian statistics were obtained from national registries. Results: The current literature supports the safety and effectiveness of LBBAP in older patients across different indications, with outcomes comparable to those reported in younger patients and a suggested cost-effectiveness. Conversely, data regarding patients affected by cardiac amyloidosis are still inconclusive. Conclusions: LBBAP represents a valuable resource for patients of all ages, but frailty is a major issue in the older population that needs to be addressed. The potential integration of this technology with defibrillator capabilities will enable an even more extensive application in the near future. Full article

This study investigates the activation potential of various activators for ferronickel slag (FNS) and the associated phase evolution. First, the existing forms of MgO in FNS were identified by analyzing its phase composition across different particle sizes. Subsequently, FNS was activated using six types of activators—Ca(OH)₂, CaO, NaOH, KOH, Na₂CO₃, and a Ca(OH)₂–gypsum composite—under steam curing at 80 °C for 7 days. The setting time, fluidity, hydration products, and mechanical properties of the activated systems were systematically examined. The results show that finer water-cooled FNS particles contain abundant amorphous phases, including amorphous MgO, which can react with Ca-based activators to form hydrotalcite—a reaction not observed with Na- or K-based activators. Compared with Na- or K-based activators, Ca-containing activators, particularly the Ca(OH)₂–gypsum combination, exhibited superior activation performance. In addition, distinct microstructures were observed: NaOH activation promoted the formation of a yarn ball-like N–A–S–H gel, while KOH activation led to a knotted-fiber-bundle-like K–A–S–H phase, the latter showing potential for enhancing the crack resistance of cement-based materials. These findings provide new insights into the activator-dependent hydration mechanisms of FNS and support its value-added utilization in sustainable construction materials. Full article

Atmospheric Rivers (ARs) are filamentary moisture pathways responsible for a large fraction of extreme precipitation and often occur as interacting filament bundles within the same synoptic regime. Existing diagnostics typically analyze ARs in isolation, despite the frequent coexistence and interaction of multiple filaments. We introduce a topological framework for AR analysis based on framed braids and framed braidoids, which encodes both the geometric interaction of AR centroids and the internal evolution of moisture transport. In this approach, AR filaments are represented as strands whose time-ordered crossings form braid words, while moisture-based framing captures internal intensification or weakening along each filament. Applying this framework to reanalysis-derived Atmospheric River track data, we construct braid and framed braid representations over sliding time windows and analyze a strongly interacting multi-filament AR episode in the North Pacific. The results show that braid-based indicators capture structural reorganizations and moisture intensification episodes that are not apparent from centroid geometry or IVT magnitude alone, offering a complementary structural perspective on atmospheric moisture transport. Full article

Background/Objective: Pacing-induced cardiomyopathy (PICM) is a common complication of right ventricular (RV) pacing, affecting 6–25% of patients with frequent RV pacing, due to electrical and mechanical dyssynchrony. Certain clinical and electrocardiographic risk factors have been identified, including high RV-pacing burden and longer paced QRS, but their ability to predict the development PICM remains limited. Additionally, other forms of PICM have been described, including heart failure with preserved ejection fraction and RV failure. The goal of this narrative review is to summarize the current evidence utilizing noninvasive imaging to identify patients predisposed to a high risk of PICM. Methods: Using a literature search in the PubMed, Scopus, Google Scholar, and the Cochrane databases from 2000 to 2025, which included but was not limited to the keywords right ventricular pacing, pacemaker-related cardiomyopathy, pacemaker-induced cardiomyopathy, biventricular pacing, conduction system pacing, His bundle pacing, left bundle pacing, echocardiography, computed tomography imaging, and cardiac magnetic resonance imaging, we reviewed randomized control trials, observational retrospective and prospective cohort studies, societal guidelines, and systematic review articles. Conclusions: Essential in the diagnosis of PICM, cardiac imaging can identify patients at risk, even before left ventricular (LV) dysfunction or symptoms develop. Pre- and early post-implantation 2- and 3-dimensional echocardiography with global longitudinal strain provides sensitive parameters for the potential development of PICM. Relative indices of contractile asymmetry have been described. Cardiac magnetic resonance imaging offers an accurate assessment of cardiac volumes and LV synchrony and can also quantify myocardial fibrosis, a significant predictor of PICM. Performing pre-device implantation imaging may help predict subsequent heart failure development and potentially can guide pacing modality selection that can mitigate this risk. Thus, an imaging-guided framework will advance the management of PICM. Full article

The broadly neutralizing monoclonal antibody 3D1 potently neutralizes SADS-CoV by targeting a conserved epitope within the heptad repeat 1 (HR1) domain of the viral spike protein. Structural and biophysical analyses demonstrate that 3D1 binds with high affinity to a specific linear β-turn motif (residues A804–N809) in HR1. High-resolution crystallography reveals that this motif sits within a deep, electrostatically complementary paratope groove. Critically, 3D1 binding competitively inhibits the essential interaction between HR1 and HR2. Notably, its recognition is not dependent on HR1’s native helical conformation, as it maintains strong binding to conformationally constrained, stapled helical peptides. Collectively, the data indicate that 3D1 neutralizes by capturing a pre-hairpin intermediate state of HR1—a transition state between prefusion and postfusion forms—thereby sterically blocking the formation of the stable postfusion six-helix bundle that is essential for membrane fusion. This work defines a precise, structure-dependent neutralizing epitope and elucidates a mechanism of action that involves trapping a key fusion intermediate, offering a valuable template for the design of broad-spectrum coronavirus therapeutics. Full article

Background. Cor triatriatum dexter (CTD) is a rare congenital heart defect where a membrane divides the right atrium into two chambers, resulting from the incomplete regression of the right valve of the sinus venosus. Due to its rarity, only individual case reports and a limited number of case series have been published to date. This study constitutes the most extensive comprehensive review conducted in this area. Eight factors were evaluated: age at diagnosis, sex, clinical presentation, electrocardiographic findings, imaging (ultrasound, CT, or MRI), associated cardiac anomalies, and patient outcomes. Methods. The electronic databases PubMed and Scopus were searched from their inception until 30 October 2025. Only case reports and case series were considered for inclusion. Studies involving foetuses, autopsies, and animals were excluded. The collected data were primarily presented as percentages. Results. One hundred fourteen studies were found encompassing 124 patients. The mean age at diagnosis was 33.3 ± 9.4 years The most common clinical presentations were dyspnoea (44.3%) and cyanosis (29.5%). The most commonly encountered ECG changes were supraventricular tachycardia/atrial flutter/atrial fibrillation (33.3%) and right bundle branch block (22.6%). On chest X-ray, cardiomegaly was noted in 46.5%. CTD was suspected or diagnosed by echocardiography in 95.2% of cases. The diagnosis was confirmed by CT and/or MRI in 34.1% of cases. A concomitant congenital heart defect was found in 67.7%, especially in the form of all kinds of atrial septal defect (38.1%) and of right valvular and right ventricular involvement (20.1%). An outcome was reported in 97/124. Surgical correction was the treatment of choice in 51.6%. Since 1991, a percutaneous approach has been employed in selected cases (5.1%). Conservative management was the treatment of choice in 43.3%. The mortality rate was 8.2%. Discussion. The principal limitation of this systematic review lies in its reliance solely on case reports and small case series, reflecting the absence of large-scale studies on CTD. Nonetheless, it constitutes the most comprehensive analysis available to date. Full article