179,350 research outputs found
Impact estimates for static spatial panel data models in R
No full textIn the present note we demonstrate how to implement the Lee and Yu (J Econom 154:165--185, 2010) procedure for fixed effects spatial panel data models available from the R (R Development Core Team, http://www.R-project.org/, 2012) package splm (Millo and Piras, J Stat Soft 47(1):1--38, 2012). Additionally, we also show how to compute the impact estimates (Kelejian et al. Open Econ Rev 17(4--5):423--441, 2006; LeSage and Pace, Introduction to Spatial Econometrics. CRC Press, Boca Raton, 2009). Unlike Matlab (MATLAB version 7.13, 2011), there was no R function specific to static panel data models for the calculation of the impact measures. After receiving numerous requests from the users of splm, we decided to extend the cross sectional functions available from spdep (Bivand, R package version 0.5-56, 2013) to spatial panel data models
Acceptance and Gamification Models of the Agon Framework, an Acceptance Requirements Framework Based on Gamification
No full textWe have been interested in developing a generic framework for modelling, analyzing and fulfilling acceptance requirements for software systems through gamification [Piras, 2016, 2017]. Our objective is to support the systematic design of engaging software that meets acceptance requirements. To meet our objective we conducted a wide review of the literature to select the most important, effective and representative user acceptance models [Ajzen, 1991, Compeau et al., 1999, Davis, 1986, Davis et al., 1992, Moore and Benbasat, 1991, Sheppard et al., 1988, Taylor and Todd, 1995, Thompson et al., 1991, Venkatesh and Davis, 2000, Venkatesh et al., 2003]. We have integrated elements of existing models to create an Acceptance Model based on goal modeling techniques [Chung et al., 2012, Horkoff et al., 2017, Li et al., 2013, Mylopoulos et al., 1992]. This model gives a generic characterization of the problem space for acceptance requirements.We have also developed a Gamification Model [Piras, 2016, 2017] that defines a design space for gamified solutions to acceptance requirements, also through a literature review. This model includes gamification concepts such as point systems (i.e., experience, redeemable, skill, karma, reputation and training points), badges, leader-boards, levels, paths, gamified training (i.e., suggestions, tricks, tours, tutorials, training paths), gamified market (i.e., rewards and market policies of redeeming, making gifts, purchasing), game roles, powers, unlockable powers, gamified community [Deterding et al., 2011, Hamari, 2015, Schell, 2014, Zichermann and Cunningham, 2011], etc., and the alternative choices a designer has when designing a gamified solution [Deterding et al., 2011, Hamari, 2015, Schell, 2014, Zichermann and Cunningham, 2011]. Our framework, named Agon5, recognizes the importance of understanding game mechanics and dynamics by applying well-known gamification patterns and guidelines Schell [2014], Zichermann and Cunningham [2011] in producing an effective gamified design.In order to obtain more details and the description of such models, the Agon Framework and its method, "Acceptance Requirements Analysis Based on Gamification", please read the following published papers:- L. Piras, E. Paja, P. Giorgini and J. Mylopoulos, “Goal Models for Acceptance Requirements Analysis and Gamification Design”, in 36th International Conference on Conceptual Modeling (ER), Springer, Valencia (Spain), 2017.- L. Piras, E. Paja, R. Cuel, D. Ponte, P. Giorgini and J. Mylopoulos, “Gamification Solutions for Software Acceptance: A Comparative Study of Requirements Engineering and Organizational Behavior Techniques”, in 11th IEEE International Conference on Research Challenges in Information Science (RCIS), IEEE, Brighton (UK), 2017.- L. Piras, P. Giorgini, and J. Mylopoulos, “Acceptance Requirements and their Gamification Solutions”, in 24th IEEE International Requirements Engineering Conference (RE), IEEE, Beijing, 2016
Impact estimates for static spatial panel data models in R
No full textIn the present note we demonstrate how to implement the Lee and Yu (2010) procedure for fixed effects spatial panel data models available from the R (R Development Core Team 2012) package splm (Millo and Piras 2012). Additionally, we also show how to compute the impact estimates introduced by Kelejian, Tavlas, and Hondroyiannis (2006) and formalized in LeSage and Pace (2009). Unlike Matlab (MATLAB 2011), there was no R function specific to static panel data models for the calculation of the impact measures. After receiving numerous requests from the users of splm, we decided to extend the cross sectional functions available from spdep (Bivand 2013) to spatial panel data models
splm : Spatial Panel Data Models in R
No full textsplm is an R package for the estimation and testing of various spatial panel data specifications. We consider the implementation of both maximum likelihood and generalized moments estimators in the context of xed as well as random effects spatial panel data models. This paper is a general description of splm and all functionalities are illustrated using a well-known example taken from Munnell(1990)with productivity data on 48 US states observed over 17 years. We perform comparisons with other available software; and, when this is not possible, Monte Carlo results support our original implementation
Splm: Spatial panel data models in R
No full textsplm is an R package for the estimation and testing of various spatial panel data specifications. We consider the implementation of both maximum likelihood and generalized moments estimators in the context of fixed as well as random effects spatial panel data models. This paper is a general description of splm and all functionalities are illustrated using a well-known example taken from Munnell (1990) with productivity data on 48 US states observed over 17 years. We perform comparisons with other available software; and, when this is not possible, Monte Carlo results support our original implementation
Funding sources, colonial legacy, and new firms’ creation in Africa
No full textThis study examines the determinants of new firm creation in Africa, focusing on external and internal funding sources and their interactions. It also explores the influence of colonial history by separately analyzing former British and French colonies. The primary goal is to help fill crucial gaps in African literature on the determinants of entrepreneurship. Given Africa's widespread poverty and underdevelopment, understanding what drives entrepreneurship is essential for job creation and economic growth. The study reveals three key findings. First, at the full sample level, remittances are the only external financing source positively associated with new firm creation, while foreign aid and foreign direct investment obstacle it. Internal sources, like savings and credit, do not show significant effects. Second, the subsample analysis reveals heterogeneous results: former British colonies' funding sources align with the overall findings, while in former French colonies, only savings support entrepreneurship. Third, considering control variables, the subsample analysis indicates two distinct entrepreneurship models: opportunity-based in former British colonies and necessity-based in former French colonies. These findings are noteworthy and provide significant policy implications at both national and international levels. Crucially, the positive role of remittances in financing new business initiatives, confirms that migration serves as a mutually beneficial arrangement for both sending African countries and the host countries
Arothron: an R package for virtual anthropology to build endocast and to perform digital reconstruction
No full textArothron is an R package [1] containing brand new tools for geometric morphometric analysis. The package comes with examples
pertaining to the field of virtual anthropology, yet it is addressed to the entire audience of geometric morphometricians. The functions
embedded in the package allow aligning disarticulated parts belonging to a single specimen (i.e. broken skull fragments), to
build internal cavities such as endocasts, and to reproduce and analyse the shapes of three-dimensional objects. Arothron functions
import and export landmark coordinates and 3D paths into ’landmarkAscii’ and ’am’ format files. The Digital Tool for Alignment
(DTA) is a landmark-based methodology which allows aligning two or more portions of a 3D mesh (i.e. a disarticulated model,
DM) by using a reference sample or model (RM) for comparison. To run DTA, a set of anatomical landmarks is defined on two
separated portions of the DM. Each point of the landmark sets is moved to the nearest vertex of the triangles. This way, each landmark
is identified by a number corresponding to a row of the vertex matrix of the mesh and its position is tracked on the 3D models
moved in the Cartesian coordinate system.The second step is the alignment via Generalized Procrustes Analysis (GPA) of each part
of the DM on each RM of the comparative sample, where the same landmark configuration as with the DM has been previously
defined. The items of the reference sample are previously scaled to the mean of the single scale factors calculated for each half of
the DM, separately, and symmetrized via reflection and relabelling, thereby producing a perfectly symmetrical, bilateral, and scaled
landmark configurations (to avoid alignment error as introduced by asymmetry). The last step consists in the quantification of the
morphological (Euclidean) distances between each part of the DM and the corresponding landmark configurations on each item in
the RM set. Computer-Aided Laser Scanner Emulator (CA-LSE) and Automatic Segmentation Tool for 3D objects (AST-3D) are
two new tools designed for the reconstruction of virtual cavities and external shapes [2]. CA-LSE provides the reconstruction of the
external portions of a 3D mesh by simulating the action of a laser scanner. AST-3D performs the digital reconstruction of anatomical
cavities as endocasts. Both tools use the definition of points of views that can be placed externally to the object (CA-LSE) or
inside the object (AST-3D). By applying these tools is possible in few minutes to build virtual cavities as endocast, maxillary sinuses
and trabecular bone. In the Arothron R package, we supplied three examples of reconstructing: the dental pulp cavity within a deciduous
Neanderthal tooth, the network of blood vessels within a human malleus bone, and an endocast of a human skull.The tools
could be used in virtual anthropology application.The digital alignment tool is efficient in find ideal alignments of broken pieces. It
could be applied as the first step in virtual reconstruction on human fossil specimens that often consist of a disarticulated fragments
such as BOU-VP12/130 (Australopithecus garhi), AL-442 (Australopithecus afarensis), OH5 (Paranthropus boisei), ATD6-15 and
ATD6-69 (Homo antecessor), Amud 1 (Homo neanderthalensis), Le Moustier 1 (Homo neanderthalensis). The easily and quickly
use of the Arothron R package to build virtual cavities may provide a new means largely applicable in virtual Anthropology.
References:[1] Profico A., Veneziano A., Melchionna M., Piras P. & Raia P., 2018. Arothron: Geometric Morphometrics Analyses. R package version 1.0.1, developer version available at
https://github/Arothron DOI:10.5281/zenodo.1218712.[2] Profico A., Schlager S., Valoriani V., Buzi C., Melchionna M., Veneziano A., Raia P., MoggifiCecchi J. & Manzi G., 2018. Reproducing the
internal and external anatomy of fossil bones: Two new automatic digital tools. American Journal of Physical Anthropology
Il Manicheismo, volume II. Il mito e la dottrina: i testi manichei copti e la polemica antimanichea
No full textIntroduzioni e traduzioni:
testi copti (a cura di S. Pernigotti e S. Demaria)
testi greci e latini (a c. di A. Piras)
testi siriaci (a c. di R. Contini)
testi medio-persiani (a c. di C.G. Cereti)
testi arabi (a c. di Alberto Ventura)
Commento ai testi:
da pp. 279 a 35
Testi greci e latini: Alessandro di Licopoli, Contro le dottrine di Mani; Egemonio, Acta Archelai, in Epifanio, Panarion 25-31; Agostino, De natura boni, Contra Faustum
No full textIntroduzione, traduzione e commento di alcuni testi classici di polemica antimanichea
QuaderniCIRD n. 16
No full textVedere la Presentazione di L. Zuccheri: http://hdl.handle.net/10077/21895. La rivista QuaderniCIRD, con il numero 16 (2018), continua a proporre contributi relativi a diverse discipline di insegnamento ampiamente fruibili in contesto didattico. In questo caso, le discipline interessate sono la Letteratura italiana, le Geoscienze e la Matematica. La prima parte del numero è monografica, essendo completamente dedicata alla letteratura e soprattutto perché, come ben illustrato nell’introduzione di Tiziana Piras, tutti e tre i contributi in essa riportati prendono spunto da testi letterari di autori giuliani e li mettono in relazione al territorio. Nel primo di questi, Edda Serra propone suggestivi itinerari nell’isola di Grado collegati a struggenti testi del poeta e scrittore Biagio Marin. Nel secondo, Daniela Picamus presenta la lettura di alcuni passi tratti da “Primavera a Trieste” di Pier Antonio Quarantotti Gambini, ripercorrendo le vie della città nel corso dell’occupazione militare da parte dell’esercito jugoslavo avvenuta alla fine della seconda guerra mondiale. Il terzo articolo, di Chiara Mattioni, conduce ancora il lettore per le vie di Trieste, con la mediazione delle narrazioni autobiografiche e dei testi dello scrittore Stelio Mattioni. La seconda parte del numero contiene tre recensioni, due relative a testi scritti e una a software. La prima, nel contesto delle Scienze geologiche, è di Michele Stoppa e riguarda il testo Geologie der Berchtesgadener Berge. Eine Einfürung in Stratigraphie, Fazies und Tektonik, di LANGENSCHEIDT E. La seconda, nel contesto della didattica della matematica, è di Verena Zudini e riguarda il testo Didattica della matematica, di BACCAGLINI-FRANK A., DI MARTINO P., NATALINI R., ROSOLINI G. La terza recensione, ancora nel contesto della didattica della matematica, è di Daniel Doz e riguarda l’app per tablet e smartphone (disponibile anche in versione online per pc) Euclidea, della HORIS INTERNATIONAL LIMITED
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