Strings of group endomorphisms

Recently the strings and the string number of self-maps were used in the computation of the algebraic entropy of special group endomorphisms. We introduce two special kinds of strings, and their relative string numbers. We show that a dichotomy holds for all these three string numbers; in fact, they admit only zero and infinity as values on group endomorphisms.Comment: 17 page

The relationship between thyroid disorders and vitamin A. A narrative minireview

: The terms "vitamin A" and "retinoids" encompass a group of fat-soluble compounds essential for human nutrition. Some of them (retinol, retinal, 9-cis-retinoic acid, tretinoin, and 13-cis-retinoic acid) are fully natural, while others are synthetic compounds used mostly for therapeutic purposes. Some evidence indicates that the nutritional status of these retinoids (i.e., the presence or absence of deficiency) is able to modulate thyroid gland metabolism. Vitamin A deficiency is tightly correlated with structural and functional impairment of the thyroid gland and is often associated with iodine deficiency. Furthermore, retinoids are involved in different immune functions, as well as in the process of activation, proliferation, and differentiation of regulatory T cells (Treg). This is particularly significant given the high prevalence of thyroid autoimmune disorders, whose pathogenesis seems to be related to the altered homeostasis of regulatory T cells. Retinoids are also involved in the modulation of gene expression via their interaction with nuclear receptors, and they also act as cofactors in cell growth and differentiation. The ability of retinoic acid to increase iodine uptake and sodium-iodine symporter activity in human thyroid cancer cell lines suggests that some retinoids and their derivatives may be of use in the treatment of different thyroid tumors. This minireview summarizes the current knowledge on the link between nutritional intake of vitamin A and various thyroid disorders

EH Performance of an Hybrid Energy Harvester for Autonomous Nodes

This paper reports the Energy Harvesting (EH) performance of a hybrid energy harvester able to collect energy form different energy sources: thermal, solar and electromagnetic. The main block of the system is the quarter-wavelength patch antenna, operating in the Industrial, Scientific and Medical (ISM) frequency band 2.4-2.5 GHz. The antenna has been designed and optimized to support a Thermo-Electric Generator (TEG) and a Solar Cell on its top. Moreover, a rectifier has been designed to work with the antenna and a DC-DC converter has been used to manage the TEG output voltage

Value generation in e-government from service-based IT integration

Understanding how value is actually generated in e-government projects is one of the most challenging, and relevant, issues in e-government research. This paper aims to investigate the contribution of service-based information technology (IT) integration for generating value in the public sector, proposing a theoretical framework based on the theory of IT conversion effectiveness. The paper illustrates this novel approach to electronic government evaluation with an exploratory case study of a service-based IT integration project developed by the City of Genoa, showing how and why IT integration can substantially contribute to value generation in the public sector. Contrarily to what one would expect according to the original theory of IT conversion effectiveness, value generation may happen even with no substantial growth in the pre-existing IT asset portfolio. In fact, what is truly important is not only the availability of IT assets (policy output), but also their proper use (policy outcome) and their final effects on policy takers (policy impact). The case study shows how a low-cost and small IT integration project based on agile information system development practices can significantly leverage the legacy systems, enhancing the overall degree of IT conversion effectiveness (first stage), with expected positive effects on policy outcomes (second stage) and policy impacts (third stage). The enabling effect of the web services technology has a central role in the overall value generation process. While addressing a literature void in the context of public sector, this theoretical approach is substantial as it can be used to evaluate and maximize the value generated by e-government projects, with a special focus on service-based IT integration project

NETWORK EFFECTS IN TECHNOLOGY ACCEPTANCE: LABORATORY EVIDENCE

This research analyzes network effects in technology acceptance on the hypothesis that larger user network the more likely is technology acceptance. Still today, empirical measurement of network effects is challenging and there is a lack of experimental evidence, particularly in technology acceptance research. To overcome this limitation we reproduce set of technology acceptance processes in a laboratory experiment, controlling for the user network size to verify if it can affect the user perceptions. The experiments conducted confirm our working hypothesis showing a significant role of network effects on key user perceptions influencing technology acceptance

Network effects in technology acceptance: Laboratory experimental evidence

This research analyzes network effects in technology acceptance. The hypothesis is that the size of the user network affects technology acceptance. Even today, empirical measurement of network effects is challenging and there is a lack of experimental evidence. In order to investigate and measure the relation- ship between network size (number of adopters) and user acceptance, technology acceptance research needs to broaden its scope and approaches. To overcome this limitation we reproduce a particular type of technology acceptance process in a laboratory experiment, controlling for user network size and testing its influence on user perceptions and, ultimately, on acceptance decisions. We measured user perceptions and analyzed the data using consolidated and tested technology acceptance models. The results confirm our hypothesis, showing a significant effect of user network size on user perceptions. Finally, we discuss the theoretical and managerial implications of our approach and findings

The enabling role of Web services in information system development practices : a grounded theory study

This study presents a grounded theory analysis of a case study in the banking industry with a view to showing the enabling role of \u201cWeb services\u201d technology in information system development practices. The grounded theory analysis of the Cashier Management System development project at the Central Europe Bank (a pseudonym) shows that Web services technology is a key technological enabler for more agile forms of IS development, characterized by incremental analysis, requirements revision, requirements emerging in use and incremental implementation. In particular, an initial in-depth analysis phase, conducted in a traditional way, is then followed, during system development, by several iterative phases of requirements revision/addition, in fulfilment of emerging or previously unplanned user needs discovered along the way. Such system development practices, enabled by the Web services technology and influenced by a variety of contextual factors, cover a middle ground between methodical and amethodical development processe