Some results on injectivity and multistationarity in chemical reaction networks

The goal of this paper is to gather and develop some necessary and sufficient criteria for injectivity and multistationarity in vector fields associated with a chemical reaction network under a variety of more or less general assumptions on the nature of the network and the reaction rates. The results are primarily linear algebraic or matrix-theoretic, with some graph-theoretic results also mentioned. Several results appear in, or are close to, results in the literature. Here, we emphasise the connections between the results, and where possible, present elementary proofs which rely solely on basic linear algebra and calculus. A number of examples are provided to illustrate the variety of subtly different conclusions which can be reached via different computations. In addition, many of the computations are implemented in a web-based open source platform, allowing the reader to test examples including and beyond those analysed in the paper

The inheritance of nondegenerate multistationarity in chemical reaction networks

We study how the properties of allowing multiple positive nondegenerate equilibria (MPNE) and multiple positive linearly stable equilibria (MPSE) are inherited in chemical reaction networks (CRNs). Specifically, when is it that we can deduce that a CRN admits MPNE or MPSE based on analysis of its subnetworks? Using basic techniques from analysis we are able to identify a number of situations where MPNE and MPSE are inherited as we build up a network. Some of these modifications are known while others are new, but all results are proved using the same basic framework, which we believe will yield further results. The results are presented primarily for mass action kinetics, although with natural, and in some cases immediate, generalisation to other classes of kinetics

Knowledge sharing by entrepreneurs in a virtual community of practice (VCoP)

PurposeThis paper examines how entrepreneurs engage in a Virtual Community of Practice (VCoP) to share knowledge. Intensity of engagement is taken as a proxy to measure the strength of knowledge sharing.Design/methodology/approachThe archival data spanning over a three-year period from ‘Start-up-Nation©’ (a VCoP purposefully setup for entrepreneurs) is used for analysis. A set of indices are introduced to measure participants’ intensity of engagement in terms of message length, message frequency and reciprocity in the knowledge sharing process. Content analysis is employed to test a sample of ‘highly engaged’, ‘moderately engaged’, ‘low engaged’ and ‘not engaged’ discussion topics as part of the on-line discourse.FindingsWe find that entrepreneurs normally use short (fewer than 100 words) or medium (fewer than 250 words) message size to contribute to the discussions. In addition, we find that senior members and discussion moderators play important roles in igniting the ‘reciprocity’ behaviour in stimulating the interest of the community with the topic discussion. We also findthat highly engaged topics usually lead to further discussion threads.Originality/valueThis is the first study of its kind to explore how entrepreneurs engage in a VCoP to share their knowledge and experiences. The set of measurement indices tested here provide a tool for the owner, designer and moderator of the VCoP to measure the utility of their website in terms of its members’ participation. In addition, the set of textual and subjective interventions identified here enable the moderator (administrator) of a VCoP to design effective interventions to facilitate on-line discourse and augment the knowledge sharing process amongst its community members

Combinatorial approaches to Hopf bifurcations in systems of interacting elements

We describe combinatorial approaches to the question of whether families of real matrices admit pairs of nonreal eigenvalues passing through the imaginary axis. When the matrices arise as Jacobian matrices in the study of dynamical systems, these conditions provide necessary conditions for Hopf bifurcations to occur in parameterised families of such systems. The techniques depend on the spectral properties of additive compound matrices: in particular, we associate with a product of matrices a signed, labelled digraph termed a DSR^[2] graph, which encodes information about the second additive compound of this product. A condition on the cycle structure of this digraph is shown to rule out the possibility of nonreal eigenvalues with positive real part. The techniques developed are applied to systems of interacting elements termed “interaction networks”, of which networks of chemical reactions are a special case

Evaluating the impact of corporate logos towards corporate reputation: a case of Persia and Mexico

Purpose - This paper examines the impact of corporate logos on corporate image and reputation in creating competitive advantage in the context of Persia and Mexico as emerging markets. This paper provides an extensive links between corporate logo and its dimension and internal stakeholders’ attitudes towards advertisement, familiarity, and recognisability as intermediaries to corporate image and reputation. Design/methodology/approach - A qualitative exploratory approach was taken, comprising 12 face-to-face interviews 14 skype in-depth interviews were conducted with graphic designers, design, communication and marketing consultant in Mexico and Persia based on attribution theory. Findings - The study posits that the more favorable the name, color, typeface and design of the company and color, the more favorable the attitude Mexican consumers have towards the corporate logo, corporate image and reputation. However, in comparison for Persia these factors have less effect on customers’ judgment and behavior, towards the corporate logo, corporate image and reputation. The research findings suggest that the selection of color in a corporate logo is related to its marketing objectives, cultural values, desired customer relationship levels with the organisation, and organisation’s corporate communications. Practical implications - Corporate logo should be considered a constructive tool that can be effectively applied to managing the image and reputation of any organization. Moreover we suggest that regional or cultural variants can play an important role while selecting the logos in different cultures. The results are helpful for communication professionals who deal with organization’s corporate identity, branding, and communication, and aim to enhance the consistency of messages both visual and written within their organization Originality/value - Corporate logo has received little attention in marketing literature and barely been researched in emerging market. This is the first research of its kind to find the effect of the compound logo in emerging markets of Persia and Mexico. It thereby adds to the corporate visual identity literature by developing of the sphere of influence of the corporate logo and its antecedents and consequences (corporate image and corporate reputation)

Some results on injectivity and multistationarity in chemical reaction networks

The goal of this paper is to gather and develop some necessary and sufficient criteria for injectivity and multistationarity in vector fields associated with a chemical reaction network under a variety of more or less general assumptions on the nature of the network and the reaction rates. The results are primarily linear algebraic or matrix-theoretic, with some graph-theoretic results also mentioned. Several results appear in, or are close to, results in the literature. Here, we emphasise the connections between the results, and where possible, present elementary proofs which rely solely on basic linear algebra and calculus. A number of examples are provided to illustrate the variety of subtly different conclusions which can be reached via different computations. In addition, many of the computations are implemented in a web-based open source platform, allowing the reader to test examples including and beyond those analysed in the paper

Pheochromocytoma – clinical manifestations, diagnosis and current perioperative management

Pheochromocytoma is a neuroendocrine tumor characterized by the excessive production of catecholamines (epinephrine, norepinephrine, and dopamine). The diagnosis is suspected due to hypertensive paroxysms, associated with vegetative phenomena, due to the catecholaminergic hypersecretion. Diagnosis involves biochemical tests that reveal elevated levels of catecholamine metabolites (metanephrine and normetanephrine). Functional imaging, such as 123I-metaiodobenzylguanidine scintigraphy (123I-MIBG), has increased specificity in identifying the catecholamine-producing tumor and its metastases. The gold-standard treatment for patients with pheochromocytoma is represented by the surgical removal of the tumor. Before surgical resection, it is important to optimize blood pressure and intravascular volume in order to avoid negative hemodynamic events

Continuance interaction intention in retailing: relations between customer values, satisfaction, loyalty, and identification

Purpose - Social media as a competitive marketing tool deliver online platforms for retailers to get closer to their consumers/visitors/shoppers through continued interaction. This study scrutinizes how customer values (functional, social, and experimental) enhance satisfaction, loyalty, identification and how such relationships, in turn, impact on user-continuance interaction intention. Design/methodology/approach – A mixed method approach was designed to identify the consumers perception towards high-end retailers of worldwide brands. 12 interviews were conducted with experts in retailing and a survey with 390 respondents. Structural equation modeling/AMOS was employed to gain insight into the various relationships and influences. Findings - To augment user-continuance interaction intention, results indicate that retail managers should focus more on customer-based values when they design marketing strategies for brand pages on social media. The findings also provide guidelines for retail marketing and social media managers to generate consumer value in the retail environment via information quality, product-related learning, and economic benefits (functional value), interaction, collaboration, and social presence (social value), and experiential value (intellectual and effective value). Originality/value - The paper offers critical managerial contributions by presenting a comprehensive picture of the condition in which a favorable brand social media page could be constructed within a brand to satisfy consumers value and achieve satisfaction, loyalty, identification, and continuance interaction intention; all of which are critical objectives for every company. In other words, a clear knowledge of the dimensions of consumer value concepts can assist retail communication managers to improve consumers/visitors/shoppers intention to continue their interaction in a competitive market. The current study is one of the very few emerging research studies to have examined the relationships between consumers/visitors/shoppers functional, values, social values, and experimental values empirically, to have further explored the relationships between the research constructs

Enhancing University Brand Image and Reputation through Customer Value Co-Creation Behaviour

This study examines the causality between university website, customer value co-creation behaviour, university brand image and reputation. Drawing upon a sample of 285 students from a London-based university and using partial least squares structural equation modelling, the findings argue that a university website is critical to generate students’ co-creation behaviour. The research findings confirm the positive impact from website features on customer participation behaviour and customer citizenship behaviour; however, website applications and features have different impacts on the dimensions of customer value cocreation behaviour, i.e. customer participation and citizenship behaviour. This study asserts the pivotal role of students’ value co-creation behaviour in creating and sustaining university brand image and reputation. This research is particularly useful for higher education (HE) institutions, by investigating and investing in their website design they can enhance students’ co-creation behaviour in the context of the increasingly competitive UK HE market. Based upon the findings, this paper offers managerial implementations for decision-makers, brand managers, graphic and web designers who wish to understand the relationship between a website and its outcomes, especially relating to corporate image and reputation

Cardio metabolic risk factors for atrial fibrillation in type 2 diabetes mellitus: Focus on hypertension, metabolic syndrome and obesity

Objective. Atrial fibrillation (AF) in type 2 diabetes mellitus (T2DM) has been little explored so far. However, there are several cardio metabolic risk factors for AF in T2DM patients, such as arterial hypertension, obesity or the metabolic syndrome. Our objective was to evaluate cardio metabolic risk factors for AF in T2DM patients. Methods. We studied the medical records of T2DM patients hospitalized in the Internal Medicine department of an emergency referral hospital in Bucharest, Romania. The study was observational, retrospective and carried out between January-June 2018. Results. The study group included 221 T2DM patients (with a mean age of 68.65 ± 10.64, ranging between 37-93 years): 116 women (52.49%; with a mean age of 70.53 ± 10.69, ranging between 37-93 years) and 105 men (47.51%; with a mean age of 66.57 ± 10.23, ranging between 38-91 years). 92 patients had AF (41.63%): 40 women (34.48%) and 52 men (49.52%). 180 patients (81.45%) were hypertensive: 103 women (88.79%) and 77 men (73.33%). 113 patients (51.13%) had metabolic syndrome: 58 women (50.00%) and 55 men (52.38%). 77 patients (34.84%) were obese: 45 women (38.79%) and 32 men (30.48%). AF patients associated obesity in 26 cases (28.26%), hypertension in 73 cases (79.35%) and metabolic syndrome in 56 cases (60.87%). Conclusions. Out of the study group, 92 T2DM patients (41.63%) had AF, men being more likely to suffer from AF than women (p=0.0288). Hypertension affected 180 patients (81.45%) and in greater proportion women vs. men (p=0.0051). The metabolic syndrome and obesity were discovered in 113 patients (51.13%) and 77 patients (34.84%), respectively, with no significant differences in terms of gender. In our research, the highest cardio metabolic risk factors for AF in T2DM were hypertension (OR = 3.6675) and the metabolic syndrome (OR = 3.3388)