Search results for "on-line"
showing 10 items of 206 documents
More is not always better—non-linear effects in crowdfunding
2019
Abstract This research focuses on crowdfunding project features and its relation with the success of this project. The main purpose is to improve probability of success of crowdfunding projects. One can argue that “more is always better” resulting in attempts of daily updates. Contrarily, backers may be weary of numerous updates to work through, indicating a possible wear-out effect, implying the existence of an optimal level of updates. Our preliminary results show that previous research, built upon linear modeling, widely ignores important aspects of the relationship between key variables. We therefore picked six key variables that were previously marked as success drivers in crowdfunding…
Distributed Leadership and the Visibility/Invisibility Paradox in On-line Communities
2011
This paper analyzes the role of distributed leadership in three on-line communities, reflecting on an observed visibility/invisibility paradox in leadership within these communities. Leaders who downplay their seniority and assume a degree of invisibility, allocating discretionary powers to subordinate levels in an organizational hierarchy, may facilitate the emergence of distributed leadership. Yet, simultaneously, leader-led relations are enabled by high leadership visibility. This paradox—that leaders need to be both highly visible and also invisible, or hands-off, when the occasion requires it—was derived from prior research into e-learning communities and tested in the analysis of disc…
Comparing Different approaches - Data mining, Geostatistic, and Deterministic pedology - to assess the Frequency of WRB reference soil groups in the …
2014
Estimating frequency of soil classes in map unit is always affected by some degree of uncertainty, especially at small scales, with a larger generalization. The aim of this study was to compare different possible approaches - data mining, geostatistic, deterministic pedology - to assess the frequency of WRB Reference Soil Groups (RSG) in the major Italian soil regions. In the soil map of Italy (Costantini et al., 2012), a list of the first five RSG was reported in each major 10 soil regions. The soil map was produced using the national soil geodatabase, which stored 22,015 analyzed and classified pedons, 1,413 soil typological unit (STU) and a set of auxiliary variables (lithology, land-use…
Evaluation of Superparamagnetic Silica Nanoparticles for Extraction of Triazines in Magnetic in-Tube Solid Phase Microextraction Coupled to Capillary…
2014
The use of magnetic nanomaterials for analytical applications has increased in the recent years. In particular, magnetic nanomaterials have shown great potential as adsorbent phase in several extraction procedures due to the significant advantages over the conventional methods. In the present work, the influence of magnetic forces over the extraction efficiency of triazines using superparamagnetic silica nanoparticles (NPs) in magnetic in tube solid phase microextraction (Magnetic-IT-SPME) coupled to CapLC has been evaluated. Atrazine, terbutylazine and simazine has been selected as target analytes. The superparamagnetic silica nanomaterial (SiO2-Fe3O4) deposited onto the surface of a capil…
Discovery of slow X-ray pulsations in the high-mass X-ray binary 4U 2206+54
2008
Context. The source 4U 2206+54 is one of the most enigmatic high-mass X-ray binaries. In spite of intensive searches, X-ray pul- sations have not been detected in the time range 10−3–103 s. A cyclotron line at ∼30 keV has been suggested by various authors but never detected with significance. The stellar wind of the optical companion is abnormally slow. The orbital period, initially reported to be 9.6 days, disappeared and a new periodicity of 19.25 days emerged. Aims. The main objective of our RXTE monitoring of 4U 2206+54 is to study the X-ray orbital variability of the spectral and timing parameters. The new long and uninterrupted RXTE observations allow us to search for long (∼1 h) puls…
The Role of General and Selective Task Instructions on Students’ Processing of Multiple Conflicting Documents
2019
This study was designed to test the role of general and selective task instructions when processing documents, which vary as regards trustworthiness and position toward a conflicting topic. With selective task instructions, we refer to concrete guidelines as how to read the texts and how to select appropriate documents and contents, in contrast to general task instructions. Sixty-one secondary school students were presented with four different conflicting documents in an electronic learning environment and were told to write an essay based on the information from the texts. Only half of the students were told to only use information from two out of the four texts to write their essay (i.e.,…
Contrasting patterns of temperature related mortality and hospitalization by cardiovascular and respiratory diseases in 52 Spanish cities.
2020
Climate change is a severe public health challenge. Understanding to what extent fatal and non-fatal consequences of specific diseases are associated with temperature may help to improve the effectiveness of preventive public health efforts. This study examines the effects of temperature on deaths and hospital admissions by cardiovascular and respiratory diseases, empathizing the difference between mortality and morbidity.
Design and realization of a DC/DC converter with a partially saturated inductor
2017
DC/DC converters, in some types of applications such as portable equipments, can require more space than it is actually available. The inductor is typically the most bulky element and the possibility to reduce its size can save up to 50% of the converter volume and area [1][2], thus increasing the power density. This reduction, however, comes with nonlinear effects caused by the saturation of the ferromagnetic core. An appropriate modelling of the inductor and of the converter circuit is needed for guaranteeing a good output power quality (Fig. 1). A Boost converter with an inductor in the partially saturated roll-off operating zone was designed and realized to study the behaviour of DC/DC …
Non-Linear Inductor Models Comparison for Switched-Mode Power Supplies Applications
2022
The use of non-linear power inductors, intended as devices exploited up to a current at which the inductance is halved, is of great interest in switched-mode power supplies (SMPSs). Indeed, it allows the use of lighter and cheaper inductors improving the power density. On the other hand, the analysis of SMPSs equipped with non-linear inductors requires appropriate modeling of the inductor reproducing the inductance versus current. This paper compares two main analytical models proposed in the literature: the former is based on a polynomial, and the latter exploits the arctangent function to reproduce the non-linearity of the inductance. Performance is compared by considering the effort of r…