The relevance of ontological commitments

In this introductory note, I describe my particular view of the notion of ontological commitments as honest and pragmatic working hypotheses that assume the existence (out there) of certain entities represented by the symbols in our theory. I argue that this is not naive, in the sense that it does not entail the belief that the hypotheses could ever be proved to be true (or false), but it is nevertheless justified by the success and predictive power of the theory that contains the concepts assumed to exist. I also claim that the ontological commitments one holds (even if tacitly so) have a great influence on what kind of science is produced, how it is used, and how it is understood. Not only I justify this claim, but I also propose a sketch of a possible falsification of it. As a natural conclusion, I defend the importance of identifying, clarifying and making explicit one's ontological commitments if fruitful scientific discussions are to be had. Finally, I compare my point of view with that of some philosophers and scientists who have put forward similar notions.Comment: Submitted for peer-revie

Some lessons for us scientists (too) from the "Sokal affair"

In this little non-technical piece, I argue that some of the lessons that can be learnt from the bold action carried out in 1996 by the physicist Alan Sokal and typically known as the "Sokal affair" not only apply to some sector of the humanities (which was the original target of the hoax), but also (with much less intensity, but still) to the hardest sciences

Anorganski katodni materiali za magnezijeve akumulatorje

High-capacity battery systems are needed for further development of portable electronics and electric vehicles. Current lithium-ion batteries are getting close to their theoretical limitations, and this research is focused on new alternatives. One of them is the use of magnesium anode, desirable for its high volumetric capacity, relative safety, availability and price. Theoretically, pairing magnesium anode with an inorganic insertion cathode offers high voltages, while conversion cathodes boast high specific capacities. Realizing these theoretical promises is not simple,and a better understanding of the basic mechanisms is needed. In the presented work, we have researched two manganese oxide polymorphs as potential insertion cathodes. Magnesium insertion into spinel and birnessite structure was investigated in aqueous and organic electrolytes. Structural changes were analysed with transmission electronmicroscopy. We confirmed the successful insertion of Mg into both structures. Severe structural degradation and transformation were detected in samples, influencing electrochemical responses of the cells. Our work on conversion materials was focused on the Mg-S system. First, we investigated the proposed mechanism of sulfur reduction and determined the final discharge product. With operando techniques, we showed that the sulfur reduction proceeds through polysulfide formation during high-voltage plateau and the precipitation of the MgS as the final product in the low-voltage plateau. Precipitated MgS was found to be amorphous with tetrahedral coordination of Mg, resembling the wurtzite structure. With obtained information and understanding, we tried to improve high polarisation and fast capacity fade of the system. The addition of Se to the S cathode did not significantly improve polarisation or capacity fading. Concentrated electrolytes, used to lower polysulfide solubility, only partially improved cycling stability. Finally, we evaluated the influence of Cu current collector on the electrochemical properties of the Mg-S system. We confirmed that the presence of Cu decreases the polarisation and improves the stability by actively participating in redox reactions. With that, the energy density of such a cell is unattractive for commercialization. With the presented research, we deepened our understanding of magnesium batteries and their fundamental issues. Hopefully, this insight will help us solve the remaining challenges preventing the practical application of the system.Razvoj prenosne elektronike in električnih vozil zahteva razvoj novih shranjevalnikov električne energije z visoko energijsko gostoto. Trenutni litij-ionski akumulatorji se približujejo teoretičnim omejitvam in raziskave se počasi osredotočajo na iskanje alternativnih rešitev. Ena od teh je uporaba magnezijeve anode, ki je privlačna predvsem zaradi visoke volumetrične kapacitete, relativne varnosti, dostopnosti in seveda cene. Kombinacija magnezijeve anode z anorganskimi insercijskimi katodami v teoriji obljublja visoke napetosti, medtem ko je glavna prednost konverzijskih materialov njihova visoka specifična kapaciteta. Razumevanje temeljnih zakonitosti delovanja tovrstnih sistemov pa je nujno, da se bomo sploh lahko približali teoretičnim vrednostim. V predstavljeni doktorski disertaciji smo med mogočimi insercijskimi katodami raziskovali dva polimorfa manganovega oksida. Vgradnjo magnezija v spinelno in birnesitno strukturo smo proučevali v vodnem in organskem elektrolitu. Strukturne spremembe smo analizirali z uporabo transmisijskega elektronskega miksroskopa. Reverzibilno vgradnjo magnezija smo potrdili v obeh materialih, v vzorcih smo zaznali večje strukturne spremembein transformacije, ki so vplivale na elektrokemijsko aktivnost celice. Naše raziskave na področju konverzijskih katod so bile usmerjene v razumevanje Mg-S sistema. Začeli smo s potrditvijo mehanizma redukcije žvepla in določitvijo končnega produkta. Z operando tehnikami smo pokazali, da redukcija žvepla v Mg-S akumulatorjih poteka prek nastanka polisulfidov na višjem platoju do formacije MgS kot končnega produkta na nižjem platoju. Ugotovili smo, da je nastali MgS amorfen, s tetraedrično koordinacijo, ki je podobna vurcitni strukturi. Z zbranimi informacijami smo želeli izboljšati visoko polarizacijo in hiter padec kapacitete v Mg-S akumulatorjih. Dodatek Se k žveplovi katodi ni bistveno vplival na zmanjšanje polarizacije. Koncentrirani elektroliti, ki smo jih uporabili za znižanje topnosti polisulfidov, so le delno izboljšali stabilnost delovanja celice. Na koncu smo analizirali še vpliv uporabe bakrovega tokovnega nosilca na elektrokemijske značilnosti sistema. Potrdili smo, da lahko prisotnost Cu zniža polarizacijo in izboljša stabilnost, tako da aktivno sodeluje v elektrokemijskih reakcijah. S tem pa se močno zniža energijska gostota sistema, kar zmanjša njegovo potencialno uporabnost. S predstavljenim delom smo poglobili razumevanje magnezijevih akumulatorjev in njihovih glavnih slabosti. S pridobljenim znanjem bomo lahko uspešneje pristopali k reševanju izzivov, ki ovirajo praktično uporabo tovrstnih akumulatorjev

Ultrasound-based non invasive intracranial pressure

Intracranial pressure (ICP) is an important monitoring modality in the clinical management of several neurological diseases carrying the intrinsic risk of potentially lethal intracranial hypertension (ICH). Considering that the brain is in an enclosed compartment, ICH leads to brain hypoperfusion and eventually ischaemia followed by irreversible neuronal damage. Traumatic brain injury (TBI), for instance, is a condition in which ICH is strongly associated with unfavourable outcome and death. Although ICP can guide patient management in neurocritical care settings, this parameter is not commonly monitored in many clinical conditions outside this environment. The invasive character of the standard methods for ICP assessment and their associated risks to the patient (like infections, brain tissue lesions, haemorrhage) contribute to this scenario. Such risks have prevented ICP assessment in a broad range of diseases like in patients with risk of coagulopathy, as well as in other conditions in which invasive assessment is not considered or outweighed by the risks of the procedure. Provided that knowledge of ICP can be crucial for the successful management of patients in many sub-critical conditions, non-invasive estimation of ICP (nICP) may be helpful when indications for invasive ICP assessment are not met and when it is not immediately available or even contraindicated. Several methods for non-invasive assessment of ICP (nICP) have been described so far. Transcranial Doppler (TCD), for instance, is primarily a technique for diagnosing various intracranial vascular disorders such as emboli, stenosis, or vasospasm, but has been broadly utilised for non-invasive ICP monitoring due to its ability to detect changes in cerebral blood flow velocity derived from ICP variations. Moreover, TCD allows monitoring of these parameters as they may change in time. Optic nerve sheath diameter ultrasonography (ONSD) is another non-invasive tool which gained interest in the last years. The optic nerve sheath is in continuous with the subarachnoid space, and when ICP increased, the diameter of ONSD enlarges proportionally to ICP. The focus of this thesis is on the assessment, applications and development of ultrasoundbased for nICP assessment in different clinical conditions where this parameter is relevant but in many circumstances not considered, including TBI and other neurological diseases ULTRASOUND BASED NON-INVASIVE INTRACRANIAL PRESSURE 17 associated with impairment of cerebral blood flow circulation. As main results, ONSD and TCD-based non-invasive methods could replicate changes in direct ICP across time confidently, and could provide reasonable accuracy in comparison to the standard invasive techniques. These findings support the use of ultrasound based non-invasive ICP methods in a variety of clinical conditions requiring management of intracranial pressure and brain perfusion. More importantly, the low costs associated with nICP methods, ultrasound machines are widely available medical devices, could contribute to its widespread use as a reliable alternative for ICP monitoring in everyday clinical practice