Ordering dynamics of the driven lattice gas model

The evolution of a two-dimensional driven lattice-gas model is studied on an L_x X L_y lattice. Scaling arguments and extensive numerical simulations are used to show that starting from random initial configuration the model evolves via two stages: (a) an early stage in which alternating stripes of particles and vacancies are formed along the direction y of the driving field, and (b) a stripe coarsening stage, in which the number of stripes is reduced and their average width increases. The number of stripes formed at the end of the first stage is shown to be a function of L_x/L_y^\phi, with \phi ~ 0.2. Thus, depending on this parameter, the resulting state could be either single or multi striped. In the second, stripe coarsening stage, the coarsening time is found to be proportional to L_y, becoming infinitely long in the thermodynamic limit. This implies that the multi striped state is thermodynamically stable. The results put previous studies of the model in a more general framework

Peering from the outside in: viscoelastic properties of the extracellular matrix dictate spatial organization and apoptosis resistance in mammary epithelial cells

The compliance of the extracellular matrix (ECM) differs between tissues and is altered in tumors. We examined the consequence of modifying the viscoelastic properties of the ECM on mammary epithelial cell (MEC) morphogenesis and apoptosis regulation. Results showed that the elastic modulus of the ECM exerts a profound effect on MEC tissue organization and gene expression that correlates with changes in actin organization and apoptosis resistance. Altering the rigidity of the ECM directly influences integrin expression and additionally modifies integrin-induced gene expression in association with actin reorganization. These data suggest that the compliance of the ECM may cooperatively regulate cell behavior by altering integrin function. Studies are now underway to investigate the possibility that these effects are mediated via changes in integrin-actin cytoskeletal dynamics

A solution for estimating the tensile yield strength from small specimens

The small punch test is an innovative test that utilises small disc-shaped specimens to assess the mechanical behaviour of materials. The main advantage is the relatively small specimen size. In this article, a modified analytical solution for the small punch maximum bend strength is proposed that is based on classical plate theory. A clear linear relationship is observed between the tensile yield strength σYS and the small punch maximum bend strength σy for both alloys and metal matrix composites. Copyright by ASTM Int'l (all rights reserved)

Polarity sorting of axonal microtubules: a computational study

We present a computational model to test a “polarity sorting” mechanism for microtubule (MT) organization in developing axons. We simulate the motor-based axonal transport of short MTs to test the hypothesis that immobilized cytoplasmic dynein motors transport short MTs with their plus ends leading, so “mal-oriented” MTs with minus-end-out are transported toward the cell body while “correctly” oriented MTs are transported in the anterograde direction away from the soma. We find that dynein-based transport of short MTs can explain the predominately plus-end-out polarity pattern of axonal MTs but that transient attachments of plus-end-directed motor proteins and nonmotile cross-linker proteins are needed to explain the frequent pauses and occasional reversals observed in live-cell imaging of MT transport. Static cross-linkers increase the likelihood of a stalled “tug-of-war” between retrograde and anterograde forces on the MT, providing an explanation for the frequent pauses of short MTs and the immobility of longer MTs. We predict that inhibition of the proposed static cross-linker will produce disordered transport of short MTs and increased mobility of longer MTs. We also predict that acute inhibition of cytoplasmic dynein will disrupt the polarity sorting of MTs by increasing the likelihood of “incorrect” sorting of MTs by plus-end-directed motors

Spinodal Decomposition and the Tomita Sum Rule

The scaling properties of a phase-ordering system with a conserved order parameter are studied. The theory developed leads to scaling functions satisfying certain general properties including the Tomita sum rule. The theory also gives good agreement with numerical results for the order parameter scaling function in three dimensions. The values of the associated nonequilibrium decay exponents are given by the known lower bounds.Comment: 15 pages, 6 figure

Student-Led Live Broadcast Tour: An Elevated Learning Journey for Tourism Students

The version of record of this article, first published in [SN Computer Science], is available online at Publisher’s website: http://dx.doi.org/10.1007/s42979-024-02729-0Drawing upon the concept of student-led live broadcasting tour (LBT), this study aims to construct and empirically test the Input-Process-Output (IPO) framework that links inputs, processes, and outputs within online tourism educational context. The sample involved students who are currently studying a tourism program in the Greater Bay Area, China. One group of students was invited as the audience with another group of students acting as tour guides to lead a live broadcasting tour. Upon completion of the tour, the audience group was invited to fll in the questionnaire survey. The data were gathered through the questionnaire survey from December 2022 to March 2023. The survey instruments were designed based on existing research and the IPO framework. The quantitative data were analysed by SPSS and SmartPLS. 5 hypotheses were developed based on the IPO framework. The results confrmed that students perceived student-led LBT positively in terms of input dimensions (intrinsic motivation and resources support), process dimension (learning climate) and output dimension (learning outcomes and satisfaction). This study gives implications to educators on how student-led LBT can be designed and implemented under the constraints of travel. The utilisation of technology ofers educators the possibility to enrich the learning experience of tourism students in a more afordable and efective way.unfunde

Delayed presentation of symptomatic breast cancers in Hong Kong: Experience in a public cancer centre

Objective Delayed presentation is an important obstacle to improving cancer treatment outcomes. We aimed to study the magnitude of this problem in Hong Kong and the factors associated with delayed presentation of patients with symptomatic breast cancers. Design Retrospective study using self-administered questionnaires. Setting Clinical Oncology Department in a regional public hospital in Hong Kong. Patients A total of 158 Chinese women with breast cancer referred to our hospital between October 2006 and December 2007 consented to participate in this study. Among these, 59 (37%) patients were referred after having surgery in private sector. Results The mean total delay (from first symptom to treatment) was 22 weeks. The mean patient delay (from first symptom to first consultation) was 13 weeks, constituting the largest component (60%) of the total delay. After symptom onset, the delay exceeded 12 weeks for consulting a doctor in 29%, and for receipt of treatment in 52% of them. Low family income (<HK$5000 per month; P<0.001) and surgery in public hospitals (P=0.013) were both independent predictors of patient delay. Surgery in public hospitals (P=0.006) and low family income (P=0.005) were the only predictors of doctor/system delay and total delay, respectively. Conclusions Delayed presentation and treatment of symptomatic breast cancer remains an important issue in Hong Kong. Apart from socio-economic factors, limited access to public medical care was likely an important contributing factor in delays related to patients as well as to doctor/system.published_or_final_versio

Oscillator model for dissipative QED in an inhomogeneous dielectric

The Ullersma model for the damped harmonic oscillator is coupled to the quantised electromagnetic field. All material parameters and interaction strengths are allowed to depend on position. The ensuing Hamiltonian is expressed in terms of canonical fields, and diagonalised by performing a normal-mode expansion. The commutation relations of the diagonalising operators are in agreement with the canonical commutation relations. For the proof we replace all sums of normal modes by complex integrals with the help of the residue theorem. The same technique helps us to explicitly calculate the quantum evolution of all canonical and electromagnetic fields. We identify the dielectric constant and the Green function of the wave equation for the electric field. Both functions are meromorphic in the complex frequency plane. The solution of the extended Ullersma model is in keeping with well-known phenomenological rules for setting up quantum electrodynamics in an absorptive and spatially inhomogeneous dielectric. To establish this fundamental justification, we subject the reservoir of independent harmonic oscillators to a continuum limit. The resonant frequencies of the reservoir are smeared out over the real axis. Consequently, the poles of both the dielectric constant and the Green function unite to form a branch cut. Performing an analytic continuation beyond this branch cut, we find that the long-time behaviour of the quantised electric field is completely determined by the sources of the reservoir. Through a Riemann-Lebesgue argument we demonstrate that the field itself tends to zero, whereas its quantum fluctuations stay alive. We argue that the last feature may have important consequences for application of entanglement and related processes in quantum devices.Comment: 24 pages, 1 figur