G. Frilli, M. Lodone (a cura di), La profezia nel pensiero del Rinascimento e della prima età moderna, Edizioni ETS 2022

Recensione del volume G. Frilli, M. Lodone (a cura di), La profezia nel pensiero del Rinascimento e della prima età moderna, Edizioni ETS 202

Current-Controlled Nanospray Ionization Mass Spectrometry

The hypothesis that direct determination of electrospray current would provide a viable method for maintaining spray stability to enable optimal nanospray analysis was tested by building a feedback apparatus capable of reading the current and readjusting the emitter voltage in real time. The apparatus consists of a current-sensing circuit that reads the voltage drop across a resistor located between the high-voltage power supply and the nanospray emitter. A low voltage proportional to the observed current is generated and sent to a data acquisition card. The information is used by a proportional-derivative-integral (PID) algorithm to calculate the magnitude of a low-voltage signal that is used to control the power supply output. Any variation of current across the sensing resistor is thus counteracted by an opposite-direction variation of the high voltage applied to the nanospray emitter. In this way, the apparatus adjusts the emitter voltage to achieve a preset value of current, which it strives to maintain over time in spite of any possible variation of the parameters influencing the spray regime. Preliminary results have shown that the feedback apparatus is capable of establishing and maintaining stable spray for samples that are usually considered challenging in traditional voltage-controlled analysis, such as those consisting of nucleic acid solutions with high salt loads. For these types of samples, the total ion count recorded in current-controlled mode was significantly more stable than that observed in voltage-controlled mode. At the same time, overall signal intensities and signal-to-noise ratios were also significantly improved. Setting the target nanospray current to a predefined value and letting the apparatus reach the target without operator intervention enabled the acquisition of viable data from solutions containing up to 2.5 M ammonium acetate, which are ordinarily difficult by traditional manual tuning. A deeper understanding of the current–voltage relationships for samples of very different compositions is expected to enable one not only to predict the target current that should be used for a certain analysis, but also to devise algorithms to change such target as a function of predictable variations of sample properties and analytical conditions. This will allow for optimal performance to be maintained during on-line gradient chromatography in which the nature of the sprayed solution may vary very widely during the course of the analysis

An information-oriented paradigm in evaluating accuracy and agreement in radiology

The goal of any radiological diagnostic process is to gain information about the patient's status. However, the mathematical notion of information is usually not adopted to measure the performance of a diagnostic test or the agreement among readers in providing a certain diagnosis. Indeed, commonly used metrics for assessing diagnostic accuracy (e.g., sensitivity and specificity) or inter-reader agreement (Cohen [Formula: see text] statistics) use confusion matrices containing the number of true- and false positives/negatives results of a test, or the number of concordant/discordant categorizations, respectively, thus lacking proper information content. We present a methodological paradigm, based on Shannon's information theory, aiming to measure both accuracy and agreement in diagnostic radiology. This approach models the information flow as a "diagnostic channel" connecting the state of the patient's disease and the radiologist or, in the case of agreement analysis, as an "agreement channel" linking two or more radiologists evaluating the same set of images. For both cases, we proposed some measures, derived from Shannon's mutual information, which can represent an alternative way to express diagnostic accuracy and agreement in radiology.Key points• Diagnostic processes can be modeled with information theory (IT).• IT metrics of diagnostic accuracy are independent from disease prevalence.• IT metrics of inter-reader agreements can overcome Cohen κ pitfalls

Philosopher dans la mort. Les Essais comme exercice de congé du soi

Figures majeures de la Renaissance, Montaigne et Bruno partagent une atmosphère culturelle analogue et se nourrissent souvent des mêmes références textuelles. En nous concentrant surtout sur Montaigne, nous verrons comment la tentative de penser le passage de l’un au multiple et du fini à l’infini les amène à théoriser une véritable herméneutique de la transformation

Pic de la Mirandole

L'entrée analyse la conception anthropologique développée par Pic de la Mirandole en passant en revue quelques points clés de sa pensée et de son œuvre

The quest for Diophantine finite-fold-ness

The Davis-Putnam-Robinson theorem showed that every partially computable $m$-ary function f(a1, ..., am) = c on the natural numbers can be specified by means of an exponential Diophantine formula involving, along with parameters a1, ... am, c,  some number k of existentially quantified variables. Yuri Matiyasevich improved this theorem in two ways: on the one hand, he proved that the same goal can be achieved with no recourse to exponentiation and, thereby, he provided a negative answer to  Hilbert's 10th problem; on the other hand, he showed how to construct an exponential Diophantine equation specifying f which, once a1, ... am have been fixed, is solved by at most one tuple < v0, ..., vk > of values for the remaining variables. This latter property is called single-foldness. Whether there exists a single- (or, at worst, finite-) fold polynomial Diophantine representation of any partially computable function on the natural numbers is as yet an open problem. This work surveys relevant results on this subject and tries to draw a route towards a hoped-for positive answer to the finite-fold-ness issue