4,308 research outputs found
CLPdyn: a cheap and reliable tool for molecular dynamics studies of organic molecules in condensed phase
No full textWe present CLPdyn, a freely available code intended to perform Molecular Dynamics simulations of organic molecules in condensed phase.[1–3] CLPdyn can handle both continuous phases (liquids, crystals) and finite-size clusters (liquid droplets, nanoparticles), and exploits the thoroughly tested Coulomb-London-Pauli atom-atom intermolecular potential[4,5]. The implementation relies on standard MD algebra, but also includes new algorithms, specifically designed to deal with isolated clusters, to (i) suppress net overall translational and rotational momenta, (ii) handle the evaporation of molecules from the cluster surface, and (iii) measure the amount of residual symmetry from the number and kind of isometries present in the cluster. Application to organic solvents (benzene, chloroform, methanol and pyridine) [2] and crystals spanning very different intermolecular recognition patterns (maleic/succinic anhydrides, alanine/glutamic acid, methylurea, 1,4-cyclohexadiene and methyl-2-amino-5-hydroxybenzoate) [3], shows that CLPdyn reliably reproduces macroscopic thermodynamic quantities, and highlights the effect of the relative strengths of intermolecular forces on rotational correlation times, self-diffusion coefficients and pair distribution functions. Possible applications of CLPdyn to the molecular–level study of non–equilibrium solution chemistry, including the early stages of crystal nuclei formation, are also discussed.
[1] A. Gavezzotti, CLPdyn, Monte Carlo and Molecular Dynamics modules, Description and user manual, www.angelogavezzotti.it (2018).
[2] A. Gavezzotti, L. Lo Presti, New J. Chem., 2019,43, 2077-2084.
[3] A. Gavezzotti, L. Lo Presti, in preparation
[4] A. Gavezzotti, New J. Chem. 2011, 35, 1360–1368.
[5] A. Gavezzotti and L. Lo Presti, Crystal Growth Des. 2016, 16, 2952–2962
Time-lagged test of Lo Presti & Pluviano (2016) employability model
No full textData were collected in three times on Italian employees from the private sector
Didattica a Distanza e ICT come fattori propulsivi di cambiamento: quali impatti sociali nelle scuole secondarie di II grado di Roma
No full textDi fronte all’emergenza nazionale legata alla diffusione del Covid-19 in Italia, le tecnologie digitali hanno consentito di portare avanti le attività ordinarie delle varie agenzie educative, attraverso lo strumento principale della Didattica a Distanza (DaD). Partendo da queste premesse, il presente contributo focalizza l’attenzione sull’impatto sociale (OEC-DAC in Stern, 2016) della DaD per valutare: la portata e l’intensità dell’innovazione metodologico-didattica richiesta ai docenti per l’organizzazione e lo svolgimento delle lezioni a distanza; l’accrescimento – negli studenti – delle competenze trasversali e di digital literacy (team working, problem solving, ecc..) potenzialmente associabili all’utilizzo delle ICT; il coinvolgimento e la collaborazione delle famiglie nel processo di valutazione e verifica degli apprendimenti. all’interno del framework della Positive Thinking Evaluation (Lo Presti, 2020)
Molecular dynamics simulation of organic crystals: Introducing the CLP-dyncry environment
No full textThe CLP-dyncry molecular dynamics (MD) program suite and force field environment is introduced and validated with its ad hoc features for the treatment of organic crystalline matter. The package, stemming from a preliminary implementation on organic liquids (Gavezzotti & Lo Presti, 2019), includes modules for the preliminary generation of molecular force field files from ab initio derived force constants, and for the preparation of crystalline simulation boxes from general crystallographic information, including Cambridge Structural Database CIFs. The intermolecular potential is the atom-atom Coulomb-London-Pauli force field, well tested as calibrated on sublimation enthalpies of organic crystals. These products are then submitted to a main MD module that drives the time integration and produces dynamic information in the form of coordinate and energy trajectories, which are in turn processed by several kinds of crystal-oriented analytic modules. The whole setup is tested on a variety of bulk crystals of rigid, non-rigid and hydrogen-bonded compounds for the reproduction of radial distribution functions and of crystal-specific collective orientational variables against X-ray data. In a series of parallel tests, some advantages of a dedicated program as opposed to software more oriented to biomolecular simulation (Gromacs) are highlighted. The different and improved view of crystal packing that results from joining static structural information from X-ray analysis with dynamic upgrades is also pointed out. The package is available for free distribution with I/O examples and Fortran source codes
Drawing (on) Cartographic Intimacies
No full textThis chapter provides both a conceptual and practice-based perspective on the ways in which emotions can be grasped, and spatially interpreted, through creative and critical map-centred activities. It also highlights the potential of the cartographic humanities to access inner worlds differently, by enhancing understanding of the psychic, somatic and social dimensions of one’s being through body mapping experiences. Drawing on examples from the HuMaps Lab (Laboratory of Cartographic Humanities) in which undergraduates mapped out both personal and larger public stories by drawing and assembling pieces of literary, visual, lyric and video narratives, the emotional force of mapping is unfolded in the terms of ‘cartographic intimacies’; here, maps are addressed as infrastructures of feelings, deep surfaces that emerge out of visceral emotions but conceived to be shareable with the outside, driving dis-orientations toward—as well as agitation and care for—humans, non-humans, memories, bodies and places
The Cartographic Lives of the Italian Fascist Empire
No full textThis chapter examines the pervasive and obsessive circulation of maps during the Italian Fascist Empire, particularly in contexts beyond traditional surveys and expeditions. While Italy’s first attempts at colonization began after its unification in 1861, it was under Mussolini's regime (1922–1943) that a more coherent imperial order was established, shaping cultural, political, economic, and social life. During this period, the relationship between geography and power became more pronounced, with the Fascist state using maps as key tools of empire-building. These maps were not merely geographic representations but were woven into the fabric of everyday life, serving as instruments of propaganda. The chapter argues that the widespread and repetitive circulation of these maps, often in subtle or unconscious ways, played a crucial role in both imagining and enacting the empire. By engaging with the sensory and embodied experiences associated with various forms of mapping—whether physical maps, map-like objects, or everyday interactions with cartographic representations—the author highlights how these tools of imperialism were integrated into daily routines, shaping perceptions and political realities. Ultimately, this study seeks to reveal how cartographic practices during Fascist rule helped sustain imperial power, acting as both vehicles for ideological control and sites of potential resistance.
The (Aesth)Ethics of Publishing Geopolitical Maps
No full textThis chapter stems from a decade of ethnographic encounters between the editors of the Handbook of Cartographic Humanities and Laura Canali, designer of geopolitical maps for the popular magazine Limes: Italian Review of Geopolitics and map artist based in Rome. Drawing from a selection of excerpts from those recurring encounters, this conversation unfolds and reflects upon the complexities of the craft of making geopolitical/poetical cartography for different publics, from that of the magazine’s readers to the map/art exhibition’s audience. The idiosyncratic experience of this mapmaker shows how ethnography is a crucial way to investigate the public dimension of cartographic authorship as it is felt by the mapmaker, as well as the decisions, ethical interrogations and precariousness it always implies, particularly in the case of geopolitical maps
Introduction: Why Cartographic Humanities?
No full textThe humanities have been part of geographical knowledge and its expression for centuries,
finding in maps and cartographic imaginations useful and intimate companions to reflect
with, challenge and advance new spatial paradigms, methods and metaphors. After the more
recent rise of the ‘spatial turn’ in the arts and humanities and the proliferation of digital
technologies in several cultural domains, new research areas such as spatial digital humanities,
geohumanities, deep mapping and map art, to name a few, have shown that the engagements
of scholars and practitioners with cartography and mapping practices have expanded
further, becoming increasingly diverse and highly mutable. In parallel to the growing fascination
with cartography that arose within various humanistic fields, in the last 15 years, we
have witnessed the emergence of ‘map studies’ as a transversal research area that is strongly
affected by humanistic approaches and methodologies. This area intersects not only more
established traditions such as the history of cartography and critical cartography but also the
multifaceted realm of ‘cultural cartography’ (Cosgrove, 2008). The Routledge Handbook of
Cartographic Humanities is precisely designed to explore the intersection and convergence
between cultural map studies and the humanities, expressing multifaceted traditions and
inclinations coming from different disciplinary, geographical and cultural contexts
Using X-ray derived charge densities to detect electron delocalization effects and non-covalent interactions
No full textBeing based on a quantum observable and measurable quantity, the Electron Density (ED) based descriptors retain the advantage of enabling a direct comparison of theoretical predictions with experimental results. We review here our most recent work aimed at evaluating whether two of such descriptors, the Source Function, SF, [1] and the Reduced Density Gradient (RDG), are able to unveil electron delocalization effects (EDEs) and non covalent interactions (NCI), respectively.
Making use of ab-initio EDs, we recently proved that the SF clearly detects EDEs in a series of supposedly electron-conjugated compounds [2]. That study is here extended to molecular crystals (benzene, a substituted binaphtyl-2-ol, citrinin), whose ED is derived from X-ray diffraction data. Regardless of the ED origin, the SF appears a useful tool to study fine details of EDEs, and independently from any symmetry constraint (e.g. / separation of the ED).
A novel NCI descriptor, based on the RDG and enabling an easy-to-catch image of either the supposedly attractive (dispersive, hydrogen bonding) or allegedly repulsive (steric) interactions, was recently proposed [3]. We have applied [4] this same tool to experimentally-derived ED’s of molecular solids (austdiol, benzene, famotidine), and discussed its performance in synergy with Bader’s analysis. We have also explored [5] the amount and type of information that is lost when the IAM replaces the “true” ED in evaluating the RDG.
References
[1] R.F.W. Bader, C. Gatti, Chem. Phys. Lett. 287 (1998) 233-238.
[2] E. Monza, C. Gatti, L. Lo Presti, E. Ortoleva, J. Phys. Chem. A 115 (2011) 12864-12878.
[3] E.R. Johnson, S. Keinan, P. Mori-Sanchez, J. Contreras-Garcia JACS 132 (2010), 6498.
[4] G. Saleh, C. Gatti, L. Lo Presti, J. Contreras-Garcia, submitted (2012)
[5] G. Saleh, C. Gatti, L. Lo Presti, submitted (2012
A realizable paraunitary perfect reconstruction QMF bank based on IIR filters
No full textIn this paper, we address the problem of realizing a paraunitary perfect reconstruction quadrature mirror filter bank based on IIR filters. The bank is devoted to the analysis of transient phenomena, in particular of seismic traces from which the information of the arrival times of the incoming phases must be extracted. We have shown recently (Lo Presti and Olmo, To be submitted) that this task requires the realization of highly selective filter banks, which makes it necessary to resort to IIR solutions. The details of the implementation of such a filter bank are addressed, with particular emphasis on the border effects which arise due to the presence of noncausal filters. Solutions which avoid both the signal scattering and the initial condition errors are proposed for the particular class of signals at hand, namely vanishing ones. The addition of zeros at the head and tail of the sequence can effectively combat distorsion in the recovered signal, and at the same time does not affect the coefficients of the decomposition. A signal support enlargement can be tolerated for the application at hand, which is focused on the data analysis. Rules are given in order to evaluate the number of zeros to be added, as a function of the employed filters. The results in terms of the reconstruction error are rather satisfactory for the considered class of signals
- …
