2,262 research outputs found
A probabilistic graphical model for assessing equivocal evidence
No full textThe Bayes’ theorem can be generalized to account for uncertainty on reported evidence. This has an impact on the value of the evidence, making the computation of the Bayes factor more demanding, as discussed by Taroni, Garbolino, and Bozza (2020). Probabilistic graphical models can however represent a suitable tool to assist the scientist in their evaluative task. A Bayesian network is proposed to deal with equivocal evidence and its use is illustrated through examples
The decisionalization of individualization
No full textThroughout forensic science and adjacent branches, academic researchers and practitioners continue to diverge in their perception and understanding of the notion of ‘individualization’, that is the claim to reduce a pool of potential donors of a forensic trace to a single source. In particular, recent shifts to refer to the practice of individualization as a decision have been revealed as being a mere change of label [1], leaving fundamental changes in thought and understanding still pending. What is more, professional associations and practitioners shy away from embracing the notion of decision in terms of the formal theory of decision in which individualization may be framed, mainly because of difficulties to deal with the measurement of desirability or undesirability of the consequences of decisions (e.g., using utility functions). Building on existing research in the area, this paper presents and discusses fundamental concepts of utilities and losses with particular reference to their application to forensic individualization. The paper emphasizes that a proper appreciation of decision tools not only reduces the number of individual assignments that the application of decision theory requires, but also shows how such assignments can be meaningfully related to constituting features of the real-world decision problem to which the theory is applied. It is argued that the decisonalization of individualization requires such fundamental insight to initiate changes in the fields’ underlying understandings, not merely in their label
Decoding a black hole metric from the interferometric pattern of the relativistic images of a compact source
No full textPhotons emitted by light sources in the neighbourhood of a black hole can wind several times around it before fleeing towards the observer. For spherically symmetric black holes, two infinite sequences of images are created for any given source, asymptotically approaching the shadow border with decreasing magnitude. These sequences are reflected by a characteristic staircase structure in the complex visibility function that may be used to decode the properties of the black hole metric. Recalling the formalism of gravitational lensing in the strong deflection limit, we derive analytical formulae for the height, the width and the periodicities of the steps in the visibility as functions of the black hole parameters for the case of a single compact and distant source. With respect to diffuse emission by the whole accretion flow, this ideal framework provides clean insight and model-independent information on the metric. These basic formulae can then be used to build visibilities for more complicated sources and track the changes induced by alternative metrics and ultimately test General Relativity. As simple examples, we include visibilities for Reissner-Nordström and Janis-Newman-Winicour metrics
Why AC/DC matters
No full textFormer "Rolling Stone" journalist, rock critic, and "New York Times"-bestselling author Bozza pens a fan's tribute to one of the bestselling--and underrated--rock acts of all time: AC/DC
A Study of Bozza\u27s Eighteen Etudes In The Form of Improvisation For Horn and New Preparatory Etudes on the Works of Bozza
No full textThis document serves as an analysis of Eugene Bozza\u27s Dix-Huit Études en Forme d\u27Improvisation pour Cor (1961), translated to Eighteen Etudes in the Form of Improvisation for Horn for the purposes of this document. I found and documented all motifs within the eighteen etudes, and categorized connections between them and Bozza\u27s compositional ouerve as displayed in Dr. Lois Kuyper-Rushing\u27s A Thematic Index of the Works of Bozza. My research takes inspiration from Dr. Kuyper-Rushing\u27s work as well as Dr. Hsing-Fang Liu\u27s research involving Bozza\u27s use of “Adoptive Transcription”, or taking old melodies from previous works and using them in new works. Involved with this document is a recording of all eighteen etudes, recorded and performed by the author at the Barth House, a local Episcopalian center in Memphis, Tennessee. A discussion of each of the 18 etudes, their connections, and the process I had taken in practicing and recording them makes up the middle section of the document. Finally, using the knowledge gained from the connections made and the recordings provided, this document will conclude with three new preparatory etudes for the horn composed by the author in the spirit of making the performance of Bozza\u27s body of work easier for future horn students. In their current state, most of Bozza\u27s Eighteen Etudes in the Form of Improvisation are simply too difficult to be played well by intermediate students
Probabilistic evidential assessment of gunshot residue particle evidence (Part I): Likelihood ratio calculation and case pre-assessment using Bayesian networks
No full textWell developed experimental procedures currently exist for retrieving and analyzing particle evidence from hands of individuals suspected of being associated with the discharge of a firearm. Although analytical approaches (e.g. automated Scanning Electron Microscopy with Energy Dispersive X-ray (SEM-EDS) microanalysis) allow the determination of the presence of elements typically found in\ud
gunshot residue (GSR) particles, such analyses provide no information about a given particle’s actual source. Possible origins for which scientists may need to account for are a primary exposure to the\ud
discharge of a firearm or a secondary transfer due to a contaminated environment. In order to approach such sources of uncertainty in the context of evidential assessment, this paper studies the construction\ud
and practical implementation of graphical probability models (i.e. Bayesian networks). These can assist forensic scientists inmaking the issue tractable within a probabilistic perspective. The proposed models\ud
focus on likelihood ratio calculations at various levels of detail as well as case pre-assessment
Decision theoretic properties of forensic identification: underlying logic and argumentative implications.
No full textThe field of forensic science has profited from recent advances in the elicitation of various kinds probabilistic data. These provide the basis
for implementing probabilistic inference procedures (e.g., in terms of likelihood ratios) that address the task of discriminating among
competing target propositions. There is ongoing discussion, however, whether forensic identification, that is, a conclusion that associates a
potential source (such as an individual or object) with a given item of scientific evidence (e.g., a biological stain or a tool mark), can, if ever,
be based on purely probabilistic argument. With regard to this issue, the present paper proposes to analyze the process of forensic
identification from a decision theoretic point of view. Existing probabilistic inference procedures are used therein as an integral part. The idea underlying the proposed analyses is that inference and decision are connected in the sense that the former is the point of departure for the latter. As such the approach forms a coordinated whole, that is a framework also known in the context as ‘full Bayesian (decision) approach’. This study points out that, as a logical extension to purely probabilistic reasoning, a decision theoretic conceptualization of forensic identification allows the content and structure of arguments to be examined from a reasonably distinct perspective and common fallacious interpretations to be avoided
Effects of nanofluid contaminated coolant on the performance of a spark ignition engine
No full textIn this work, the effects of alumina nanoparticle contaminated coolant on the performance of a small Spark Ignition engine are investigated by 1D and 3D models. An analysis regarding the alumina nanofluid properties is carried out, and, in particular, a reliable correlation for the thermal conductivity ratio between nanofluid and base coolants is selected. Firstly, a single-cylinder 3D-CFD model of a similar engine cooling system is developed in Star-CCM+ and it is employed to derive the relative increase of the convective in-cylinder heat transfer coefficient. The latter takes into account the geometrical effects of the cooling system, the flow conditions and the nanofluid characteristics. Secondly, a 1D engine model is developed and validated against the available experimental findings with standard coolant fluid. The model is then employed, in a predictive way, to perform full and part load analyses, where the 3D-predicted heat transfer coefficient of the nanofluid contaminated coolant is imposed as an input. The outcomes reveal the potential of the considered nanofluid to achieve fuel consumption improvements (up to about 5.4%) at full load, mainly due to decreased knock tendency and reduced mixture over-fuelling, while minor fuel consumption penalizations (about 1.0 %) are observed at low loads
Il significato delle evidenze: l'importanza dello scienziato forense nella prevenzione dell'errore
No full textIl ruolo della scienza forense è quello di garantire la qualità scientifica dell’elemento di prova trasmesso e discusso in sede dibattimentale, e che – sempre più sovente – rappresenta il perno fondamentale sul quale si basa un verdetto di condanna.
In riferimento alla prova detta scientifica, cioè all’utilizzo in sede dibattimentale di elementi di prova come il DNA, le impronte digitali o le micro-tracce (frammenti di vetro o di pitture, fibre tessili, residui di polvere da sparo, ecc.), è ormai accertato che errori d’analisi e di valutazione abbiano dato origine ad errori giudiziari. Ne sono la prova i casi analizzati dalla fondazione Innocent Project e pubblicati in alcuni articoli scientifici. Non è così infrequente che vengano commessi errori da parte degli operatori di polizia scientifica durante la fase di ricerca delle tracce sui luoghi di un crimine, di raccolta e di trasporto delle stesse o durante la raccolta di elementi comparativi provenienti dai luoghi, da persone sospettate o dalle vittime. Anche durante la fase di analisi nei laboratori specializzati dei reperti raccolti possono verificarsi errori. Contaminazioni sia sui luoghi dell’intervento o in fase di analisi possono caratterizzare in modo errato i reperti. Le analisi possono infatti mettere
in evidenza false associazioni tra le caratteristiche analizzate sui reperti e quelle degli elementi di comparazione (per esempio il profilo genetico di un sospetto) e contribuire
all’incriminazione di un sospetto erroneamente ritenuto all’origine di un dato reperto. Questi aspetti hanno indotto in errore varie Corti di giustizia.
Secondo i dati pubblicati dalla fondazione Innocent Project americana, e inerenti
prevalentemente a casi da loro analizzati dove la prova genetica del DNA ha svolto un ruolo fondamentale nel giudizio, una parte cospicua degli errori giudiziari individuati, sono stati alimentati da criticità connesse ai risultati delle analisi sui reperti scientifici. Il problema non si limita alla sola gestione della prova genetica; sono stati ugualmente riconosciuti casi di errori giudiziari alimentati da un apporto informativo fuorviante connesso ad altri tipi di tracce.
Oltre alla negligenza colpevole da parte di scienziati forensi, che può portare a perseguire e successivamente condannare persone innocenti per crimini che non hanno commesso, vi sono lacune di base caratterizzanti l’uso delle scienze forensi che possono talvolta spingere gli investigatori in direzioni sbagliate o i giudici a verdetti ingiustificati da un punto di vista scientifico. Questo capitolo presenterà alcuni esempi e cercherà di sottolineare come lo scienziato forense debba garantire la necessaria qualità al suo operato.
Sembra dunque superfluo ricordare come il ruolo svolto dagli esperti che operano sui luoghi e nei laboratori sia di primaria importanza per garantire credibilità al risultato scientifico. Questo aspetto, seppur fondamentale, non è sufficiente a scongiurare errori giudiziari. È imperativo saper inquadrare logicamente le conclusioni peritali, ed è su questo punto che si focalizzerà questo capitolo.
Partendo dal diffuso ricorso alla prova del DNA nella pratica legale e dal generale
riconoscimento di un’aura d’infallibilità che spesso lo contraddistingue, sarà possibile illustrare questo aspetto facendo luce su alcuni errori commessi quotidianamente nella gestione di questo elemento di prova
Un monumento nel monumento. L’esedra marmorea di epoca pre-neroniana reimpiegata nel vano F del Ploutonion
No full textNel 2018 sono state scavate le sostruzioni del vano F, fino a raggiungere il piano di roccia al di sopra della grotta del Ploutonion. Questo lavoro ha permesso di documentare i blocchi marmorei e calcarei di reimpiego di cui è composto il vano F, riconoscendo numerosi elementi pertinenti a edifici più antichi smantellati prima della costruzione del portico neroniano
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