This paper addresses the robust control of uncertain sampled-data systems. Conventional shift-operator models become numerically ill-conditioned at high sampling frequency. To overcome this difficulty, the Delta-operator framework is adopted. It preserves mathematical consistency between continuous-time and discrete-time representations. An adaptive sliding-mode control (SMC) strategy and a generalized discrete-time reaching law are proposed within this framework. The reaching law unifies various reaching dynamics. A dual-layer adaptive uncertainty envelope is constructed to reject complex disturbances. The first layer compensates for the slowly-varying mean of the lumped disturbance; the second layer bounds the fast residual. A Lyapunov-based analysis proves closed-loop stability. The sliding-mode variable converges to a quasi-sliding mode (QSM) band in finite steps. The framework applies to systems with matched and projected unmatched disturbances. Simulations on a switched reluctance motor (SRM) and an inverted pendulum-cart (IPC) indicate that the strategy achieves robust tracking precision, rapid convergence, and substantial chattering reduction.
Frontline hotel employees are expected to notice changing guest needs and initiate service improvements before formal procedures can be adjusted, yet less is known about whether occupation-specific stigma constrains such proactive behavior. Using cognitive-affective personality system (CAPS) theory, this study examines how perceived occupational stigma undermines proactive customer service performance (PCSP) among frontline service employees. We propose two psychological routes-a cognitive route through organization-based selfesteem (OBSE) and an affective route through harmonious work passion (HWP)-and examine core selfevaluations (CSE) as a boundary condition. Across a scenario experiment, a 2 & times; 2 experiment, and a threewave field survey, perceived occupational stigma consistently reduced PCSP. OBSE and HWP transmitted this effect, and CSE weakened the negative indirect pathways. These findings clarify how occupational stigma is processed in frontline hospitality work and offer guidance for sustaining proactive service behavior in stigmatized roles.
Visible-light-promoted and EDA complex-driven multi-component strategy has been developed for the construction of beta-hydroxy dithiophosphinates through the hydroxylphosphinothiolation of alkenes with elemental sulfur and secondary arylphosphines in air. This photocatalyst-free difunctionalization of alkenes allows introducing both hydroxy and dithiophosphinate structural moieties into one molecular framework under mild condition. Using molecular oxygen as green oxygen source and elemental sulfur as the malodorous sulfur source, a number of beta-hydroxy dithiophosphinates could be conveniently obtained in moderate to good yields. Mechanistic studies indicated that this photochemical reaction proceeded via radical anti-Markovnikov addition process. The formation of an EDA complex between the diarylphosphinodithioic anion and the alkene is key to initiating this transformation. V. on behalf of Chinese Chemical Society and Institute of Materia Medica, Chinese Academy of Medical Sciences.
Tissue stiffness assessment plays a critical role in the clinical diagnosis of liver fibrosis and the differentiation of benign from malignant tumors, among other conditions. Conventional magnetic resonance elastography (MRE) enables noninvasive evaluation of tissue stiffness but relies on dedicated external vibration devices, which limits its widespread clinical adoption. Virtual magnetic resonance elastography (vMRE) has emerged as a promising branch of MRE and has attracted increasing attention in recent years. vMRE is primarily based on microstructural analysis using diffusion-weighted imaging (DWI), from which virtual shear modulus is derived by modeling water molecule diffusion, thereby eliminating the need for additional mechanical excitation hardware. Tissue elastic parameters can also be estimated from conventional MRI sequences, offering advantages in convenience and compatibility. However, the diagnostic performance of vMRE relative to conventional MRE remains controversial. Existing studies are mostly small-sample, single-center investigations, and both the models and scanning protocols have yet to be standardized. Systematic reviews and standardized guidelines are still lacking. This article reviews the technical characteristics, application progress, influencing factors, and optimization strategies of vMRE, aiming to provide a reference for its clinical translation and future research.
Motivated by the classification of one-to-one rational functions of low degree in terms of their equivalence classes, we determine all many-to-one (including one-to-one) rational functions of degree two or three on the projective line explicitly in terms of their coefficients. Furthermore, we study the linear-fractional equivalence classes and the value sets of these rational functions. As an application, we characterize two classes of many-to-one quadranomials using their coefficients. These one-to-one quadranomials unify and generalize many results in the literature. (c) 2026 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY license (http:// creativecommons.org/licenses/by/4.0/).
