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La cessazione della materia del contendere: profili di diritto interno e comparato
No full textSotto il nome di cessazione della materia del contendere è nota quella particolare tipologia di pronuncia, di origine pretoria, cui si fa ricorso quando sopravvenga, pendente il giudizio, un accadimento dotato dell’attitudine a eliminare la ragione del contrasto insorto tra le parti. Nel presente lavoro, si è inteso calare la locuzione “cessazione della materia del contendere” nel più ampio contesto relativo allo studio della problematica riconducibile al fatto sopravvenuto. La formula, infatti, non rappresenta che la sintesi della soluzione congegnata dalla giurisprudenza civile per fronteggiare simile eventualità. Tale più ampia prospettiva d’indagine ha consentito di ravvisare dinamiche e questioni comuni anche in altre branche processuali (quali il sistema processuale amministrativo e tributario) o in altri ordinamenti giuridici (in particolare l’ordinamento tedesco, austriaco e francese); ciò ha reso fecondo, e allo stesso tempo familiare, lo studio del fatto sopravvenuto al di fuori del processo civile italiano.
L’analisi ha consentito di mettere in luce alcuni profili di grande rilievo: anzitutto, quanto all’ambito applicativo della formula, si è inteso operare una bipartizione fondamentale tra le ipotesi in cui il sopraggiungere del fatto determini la sopravvenuta estinzione della situazione giuridica dedotta a titolo della domanda (comportandone così la sopravvenuta infondatezza o inammissibilità) e quelle in cui l’evento non rappresenti altro che la concreta manifestazione dell’avvenuta autocomposizione della lite. L’indagine ha messo in luce come il ricorso alla formula di cessata materia del contendere sia avvenuto sulla base di esigenze diverse: ragioni di schietta giustizia per il primo gruppo di ipotesi (la giurisprudenza non reputava, semplicemente, giusto che la parte sostanzialmente vincitrice risultasse soccombente dal punto di vista processuale) e ragioni di opportunità per l’altra categoria di fattispecie (il ricorso alla formula de qua è stato suggerito dalla volontà di arginare il potere dispositivo delle parti, al fine di salvaguardare la libertà di apprezzamento e giudizio del giudice). Una volta ricostruito il perimetro applicativo si sono indagati i caratteri dell’istituto: la soluzione congegnata dalla giurisprudenza civile risulta essere completamente imperniata sul requisito dell’accordo. Più precisamente, all’incontro delle volontà delle parti viene riconosciuta una duplice valenza e una duplice sfera di efficacia: l’accordo relativo al sopraggiungere dell’evento può determinare, in alcuni casi, la sopravvenuta carenza di interesse ad agire e, in altri casi, l’estinzione radicale del processo. In quest’ultima eventualità, l’accordo va inteso quale esercizio congiunto del potere dispositivo riconosciuto alle parti, al quale la giurisprudenza ricollega la conseguenza di porre nel nulla il giudizio e la pregressa attività processuale, ad eccezione delle sentenze già passate in giudicato.
In definitiva, la soluzione predisposta dalla giurisprudenza civile relativamente alla problematica del fatto sopravvenuto consiste nell’attribuire una particolare efficacia – dispositiva del processo oppure modificativa dei caratteri propri del fatto – all’accordo tra le parti, il che potrà avvenire solamente allorquando il fatto sopravvenuto possegga la qualità di elemento risolutore della controversia dedotta in giudizio. Non sempre, però, l’avvento del fatto sortisce l’effetto di acquietare le parti: può darsi che l’accordo non si formi perché il convenuto non concordi sulle conseguenze giuridiche riconducibili all’evento oppure perché l’attore ambisca a ottenere una pronuncia di merito quanto alla domanda spiegata. Il permanere del dissenso tra le parti preclude una terminazione anzitempo del processo per avvenuta cessazione della materia del contendere. Preso atto dei limiti della soluzione giurisprudenziale, ci si è soffermati sull’ipotesi di mancato accordo, analizzando l’efficacia e l’incidenza, sul processo in corso, dei diversi fatti sopravvenuti. La soluzione proposta si presenta diversificata a seconda della tipologia di fatto sopravvenuto: per le ipotesi di autocomposizione della lite si ritiene che la soluzione auspicabile sia quella in grado di preservare l’autonomia e la libertà decisionale dell’organo giudicante, mentre, per le ipotesi di sopravvenuta estinzione della situazione giuridica dedotta a titolo della domanda, la soluzione potrebbe essere nel senso di onerare l’attore di porre in essere una riduzione della propria domanda. Pertanto, qualora il fatto sopravvenuto non comporti la riappacificazione tra gli originari contendenti, oppure, semplicemente, la parte ambisca a ottenere una pronuncia di merito idonea al giudicato, si ritiene che l’attore possa adeguare la situazione processuale alla mutata realtà sostanziale mediante una riduzione della domanda al substrato di mero accertamento (proprio di tutte le tipologie di domanda giudiziale). Così facendo, la domanda – ridotta – conserverebbe la propria efficacia propulsiva, in grado di condurre il processo sino a una sentenza di merito favorevole all’attore
Downstream suspended sediment dynamics of reservoir sediment flushing
No full textReservoir sediment flushing is increasingly considered beneficial to reduce sedimentation of reservoirs and maintain sediment supply downstream of impounded rivers. Nevertheless, flushing of the accumulated sediments downstream of the dam also bears numerous negative impacts. In this study, first the most important downstream impacts of fine sediment releases of flushing were identified based on previously published research of twenty case studies in eleven countries. The results showed that the long-term as well as short term biological and physical impacts decreased with distance from the dam. The temporal scale of impacts on macro-invertebrates could span from few weeks or a month to several months while the effect on fish could last for a number of years. The impacts on downstream vegetation dynamics is driven by many years of flushing activities. The study also enabled proposing generic management strategies aimed to reduce the impacts. Second, fine sediment transport in coarse immobile bed, which is a common phenomenon downstream of dams during flushing releases, dam removal and also in many mountain and canyon rivers, was investigated. Particularly, the dynamics of the downstream erosion and transport of fine sediments released during sediment flushing was investigated based on a series of flume experiments that were carried out in immobile gravel bed and using a one-dimensional (1-D) suspended sediment transport model developed in the present study. In the framework of the flume experiment, firstly gravel bed roughness, porosity and roughness density were exclusively extracted from gravel surface elevation data in which developing a spatial filter to overcome elevation errors was carried out. Secondly a new technique to acquire fine sediment erosion in immobile coarse bed in running water condition was developed. The method proved to be the back bone of all fine sediment erosion experiments conducted in the present study and could be used for similar studies. This study presents a first work of direct measurement of erosion rate and characterizing its spatial heterogeneity in gravel bed. The experimental data of erosion rate of fine sediments showed that it varied spatially with high erosion rate on the stoss side of gravels and less on the lee side conforming to sweeps and ejections characteristics in coherent flow structure of gravel bed flows. Erosion rate was significantly affected by increase in roughness of immobile gravel bed with high erosion rate noticed when sand level was reduced although the effect on stream-wise velocity was not significant. The vertical profile of erosion rate was found to decrease linearly and showed an exponential decay in time in the gravel matrix.
Third, a new non-equilibrium erosion rate relation is proposed. Drag force profile in the interfacial sublayer of clean gravel bed was found to be scaled well with roughness density and allowed predicting the effective shear stress distribution available for fine sediment entrainment with an empirical equation. The new relation is a modified version of the pick-up rate function of van Rijn (1984b) in which the predicted shear stress in the roughness layer was implemented. The most important finding was that if the shear stress distribution in the interfacial sublayer is predicted, a relation for sand bed condition can be applied to predict fine sediment erosion rate in immobile gravel bed. This approach is conceptually superior to previous approaches where erosion rate in sand bed condition was scaled empirically for various fine sediment bed level within the interfacial sublayer. Finally, the effect of the interaction between hydrodynamic and sediment wave dynamics of sediment flushing on spatial pattern of sediment deposition was investigated. The 1-D model was developed to include major processes observed in sediment flushing: sediment wave celerity correction, variable bed roughness, bed exchange in immobile bed, hindered settling velocity and rough bed porosity. The proposed erosion rate relation showed encouraging results when implemented in the 1-D model. The wave celerity factor did not show significant effect on the spatial lag in immobile bed condition although was significant in sand bed condition. Variable bed roughness modified both the flow field and sediment deposition in which larger length of sediment deposit was noted. The immobile bed porosity allowed modelling clogged depth of fine sediments. The model was also found to be very valuable to investigate flushing scenarios that reduce significant deposition through the analysis of the dependence of deposition on peak-to-base flow and intermittence of releases. The highest peak-to-base flows produced the longest and thickest region of deposition while those with the lowest ratio produced the shortest and thinnest. A single flushing release followed by clear water release reduced area or length of sediment deposition more than intermittent flushing followed by inter- and post-flushing clear water releases. In the latter case, the peak of concentration reduced but remained higher for longer duration than the former, which suggests that a large quantity of clear water release has to be available.
Overall, the present research represents a step forward in understanding relevant processes involved in the downstream transport of fine sediments released during sediment flushing and the associated impacts that can help the development of better management strategies and predictive tools
I profili processuali dell'automatic stay nel diritto fallimentare statunitense
No full textLa locuzione automatic stay è oramai entrata a far parte del comune lessico dello studioso di diritto fallimentare italiano, a ragione delle più recenti riforme che, nell’ambito delle cd. procedure negoziali di composizione della crisi, hanno introdotto meccanismi volti a produrre in via automatica una protezione anticipata a favore del debitore, in evidente recezione del sunnominato istituto statunitense. Il presente studio si prefigge dunque l’obiettivo di analizzare in profondità, e per la prima volta nella letteratura giuridica italiana, l’automatic stay nel diritto fallimentare statunitense, al fine di verificare se ed entro quali confini l’odierna equiparazione possa dirsi giustificata. Lo studio procederà, dunque, dall’analisi storica dell’istituto, al fine di individuarne l’esatta scaturigine e la reale natura giuridica – la quale avrà diverse ricadute sul piano della disciplina operativa della protezione, specie con riguardo all’ipotesi di sua violazione -, per poi trascorrere alla disamina dei profili funzionali ed applicativi del medesimo, con speciale riguardo alle ripercussioni che la sua operatività esplica sul piano processuale. L’analisi condotta consentirà alfine di verificare che, a discapito dell’impressione che si possa maturare prima facie, di un meccanismo di protezione assai più rigido e garantistico rispetto a quello predisposto dall’ordinamento italiano, l’automatic stay presenti, viceversa, aspetti di flessibilità – e con essa di derogabilità alle regole del concorso -, del tutto inediti e sconosciuti nella realtà domestica
Le scepticisme comme méthode dans l'œuvre de Denis Diderot
No full textSkepticism as method in the work of Denis Diderot.
The aim of this research is to point out the characteristics of the reception of Skepticism in Diderot’s work, through an analysis of the Skeptic arguments and rhetorical devices
that can be identified in Diderot’s writingsέ τur investigation reveals the presence of recurring Skeptic elements both in the early works and in the maturity, including the contributions to the Encyclopédie. Another essential topic is the use of Skepticism as a
method that does not consist only in the preliminary application of skeptic’s arguments to the subject discussed by the philosopherέ We also show that Diderot’s Skeptic
method entails not only the use of some typical arguments, but also the adoption of peculiar stylistic choices. We claim that this Skeptic streak explains some singularities
of Diderot’s philosophy and of his materialismέ A deeper understanding of the central role played by the Skeptic themes in Diderot’s thinking makes a significant contribution to the studies on Skepticism in the Enlightenment, which emerges like a plurality of
positions and forms of philosophical heritages. For these reasons we do not only present a comparison between Diderot and his skeptic sources, but also with others Enlightenment philosophers like εontesquieu, Voltaire, D’Alembert and David Hume
Biodegradable stents made of pure Mg and AZ91 alloy through SPS sintering
No full textThe implantation of stents is an effective procedure to unblock the arteries of patients with serious heart problems. Traditionally, stents are made of inert materials such as stainless steel and titanium alloys. It has been shown that the traditional stents can cause restenosis or thrombosis. In recent years the proposal of biodegradable stents is attracting the interest of the industry and the research, since the stent is mechanically needed only in the first year, eliminating the problems caused by the long duration of the implant. Magnesium (Mg) alloys are of increasing interest because of their engineering properties, including the high strength to density ratio. Recently, they have been also proposed as biomaterials for the production of bioabsorbable stents and for other medical devices due to its harmless effect to human body when compared with other structural materials. In this work, the possibility to produce biodegradable stents made of magnesium starting from the powder is investigated. Pure Mg and the AZ91 Mg powders were used in the present study. Pure Mg powder was sintered by Spark Plasma Sintering at 400 and 470 °C, and the AZ91 powder was sintered at 400 °C without homogenization and at 470 °C after homogenization. The preforms produced by sintering were then submitted to hot compression, rod extrusion and tube extrusion at 330 and 380 °C with different strain rates. During all the process was not possible to obtain recrystallization or grain refinement on pure Mg, and after the tube extrusion it has shown a high brittleness and sever defects, which led to the decision of proceed only with AZ91 alloy. The AZ91 presented good recrystallization in al process, always following the Zener-Hollomon relation. The grain size obtained was as small as 1.5 μm. The AZ91 tube was then submitted to manual machining and laser cutting and it was possible to obtain the stent precursors. The results of the present investigation have demonstrated the suitability of the proposed route for producing Mg-based stents. It is clear, however, that the process has to be further optimized, investigating also the possibility of using different types of powder with a tailored composition
Commodity Price Volatility: Causes, Effects and Implications
No full textAgricultural commodities experienced substantial increases in prices over the most recent decade with major surges in both 2007-08 and again in 2010-11. These price movements coincided with sharp rises in energy prices, in particular crude oil. Sharp increases in agricultural prices were not uncommon, but it is the short period between the recent two price surges that has drawn concerns and raised questions. What were the causes of the increase in world agricultural prices and what are the prospects for future price movements? Were the trend driven by fundamental changes in global agricultural supply and demand relationships that may bring about a different outcome? What are its implication on global food security and sustainability? Several authors have discussed the factors lying behind the sharp food price increases over the period 2007-11 though no consensus has been reached on the cause of these phenomena. Rapid economic growth in China and other Asian emerging economies, decades of underinvestment in agriculture, low inventory levels, poor harvests, depreciation of the U.S. dollar, and financializiation and speculative influences are among the factors cited as leading to high levels of commodity prices. The diversion of food crops as bio-fuels stands out as an important and new factor that many have seen as accountable for the food price spikes. The price spikes were also associated with increased price volatility in commodity prices. The sudden and unexpected rise in world food prices in recent decade has drawn the attention of policy makers to agriculture and this has led to the debate about the future reliability of world markets as a source for food. Increasing volatility has been a concern for most agricultural producers and for other agents along the food chain as it renders planning very difficult for all market participants. Price volatility can have a long run impact on the incomes of many producers and the trading positions of countries and can make planning on production more difficult. The fear of further spells of volatility in food prices has prompted efforts in designing and proposing price stabilizing mechanisms both at international and national levels. This fear has been driven by the recognition that a new set of forces may be driving drive food prices and their volatility trend. These forces emerge from linkages between the agricultural and the energy markets, the role of financial and currency markets, collectively with the wider macroeconomy, which together, render agricultural markets much more exposed to shocks. The first chapter examines food and energy commodity price volatility over the past decade. The objective of this chapter is to analyse the evolution of this relationship considering the role played by biofuels. It aims at verifying whether the increased grains-crude correlations has led to greater grains volatility as shocks from the crude oil markets are transmitted into the grains market. It focuses on two main issues. Firstly, it establishes whether food and energy commodity markets have become more volatile in recent times. Secondly, it analyses the nature of relationship between food and crude oil prices. In particular, it investigates whether the volatility in food commodities is now driven by the transmission of shocks from the crude oil market as a result of increased biofuel production and consumption. The second chapter focuses on the structural changes in food and energy prices and price relationships given the role of biofuels and biofuel policies in the United States. Increases in energy prices, the boom in biofuel production and government policy interventions have led to questions in relation to the stability in the long run relationships between food and energy commodity prices. This chapter investigates the assertion that the advent of biofuels has altered the nature of the relationship between energy and agricultural markets. The main hypothesis of this second chapter is that recent market and policy events may have induced changes in the relationship between food and energy markets. The third chapter quantitatively assesses households’ welfare dynamics in the recent years. Given the recent international shocks and market related shocks, the objective of this chapter is to quantitatively assess poverty and vulnerability dynamics in Tanzania between 2008 and 2012
NMR Characterization of Sol-Gel derived Hybrid Nanonmaterials: insight on organic-inorganic Interfaces
No full textThis thesis is focused on the synthesis and structural characterization of hybrid Organic-Inorganic materials with different application fields (materials for VOC sensing and for polymer–based nanocomposites), exploiting the conventional sol-gel method or the Nano Building Block (NBBs) approach with the in situ water production route.
In the first part of the work the co-condensation of TEOS and organofunctional alkoxysilanes allowed preparation of Hybrid Sol-Gel Networks The synergic use of XRD with NMR allowed to study in deep the phase interaction. The hybrid coatings, prepared by dip-coating technique demonstrated similarity in structural features with the bulk xerogels. Two different approaches were combined to study the coatings sorption ability towards selected Volatile Organic Compounds (VOC). The coatings appeared promising in the field of detection and removal of VOCs at low temperatures, possessing the ability to quickly desorb entrapped volatiles. Fine adjustments of such hybrids can allow to discriminate between similar compounds and decrease the water sorption phenomenon, since not only the microstructure, but the polarity of the effective hybrid coatings surface plays decisive role in sorption process.
In the second part of the work the synthesis parameters were fine-tuned in order to obtain Si-based SH–functionalized NBBs. The water provided in-situ through the esterification reaction of chloroacetic acid and 1-propanol enabled the hydrolysis-condensation of –SH functionalized alkoxysilane. The choice of exploited catalyst (TFA or DBTL) and esterification reaction parameters variations clearly ruled out the preferences in NBBs structural units formation. Varying the reaction temperature conditions allowed to follow the kinetics of esterification reaction and relate the water production rate to the kinetics of NBBs growth, highlighting strong correlation of H2O availability to condensation extent. The complementary exploitation of multi-nuclear NMR, FTIR and GPC techniques elucidated in full complexity the NBBs structural features development during the reaction
Eco-hydraulic quantication of hydropeaking and thermopeaking: development of modeling and assessment tools
No full textRiver reaches worldwide historically experience morphological regulations, as channelization, as well as flow regime alterations, which often lead to degradation of freshwater ecosystems. In last seven decades a large number of dams have been designed and built worldwide contributing to such river hydromorphological alterations. In alpine and piedmont regions river reaches often experience anthropogenic flow regime alteration due to hydropower production. The fluctuating flow regime typical of river reaches downstream hydropower plant releases (hydropeaking) is known to produce several adverse ecological effects, strongly linked to morphological characteristics of the downstream channel. Hydropeaking can also alter the thermal regime of the receiving water body (thermopeaking) if released hypolimnetic water has different temperature from surface water; also thermopeaking can have adverse consequences on river environment. In a changing world with respect to renewable energy production but also to global warming, the understanding of hydropeaking and thermopeaking ecological impacts represent a lively research challenge.
The first part of the present thesis is dedicated to the characterization and quantification of hydropeaking and thermopeaking alterations. Adopting a statistical approach on an extended dataset of Alpine and Norwegian rivers, a suite of indicators have been designed and exploited to identify the degree of alteration of both hydrological and thermal regime. The study provides two screening tools that can be exploited by environmental managers in the identification of critically altered river reaches. The second part is dedicated to the development of a two-dimensional numerical shallow-water model able to simulate surface water passive tracer transport over complex morphologies, exploitable in the numerical investigation of river thermal transport dynamics. In the third part the interaction between hydropeaking waves and receiving reach morphology has been investigated via numerical modeling. The work consists on a first quantitative attempt to investigate the eco-hydraulic response of river reaches with different channel morphologies to hydropeaking waves of different intensities. Such general approach can be applied to a specific case to support the choice of the most effective river restoration strategy leading to the optimal specific eco-hydraulic conditions. Finally, the last part reports an application of the designed approaches and tools to Lundesokna River, a Norwegian river affected by hydropeaking
The mechanics of submerged granular flows
No full textThe thesis tackles the mechanics of submerged granular flows driven by gravity, focusing on the rheological formulations and on the numerical solutions of the equations that govern this type of flow. In particular, a two-phase approach is assumed. The liquid phase, usually water, is described with a Newtonian rheology. The rheology of the granular phase depends on the type of contacts among the particles. Two opposite conditions are identified: if the contacts among particles are instantaneous the regime is named collisional, while, when the contacts become long lasting and involved more particles at the same time the regime is called frictional. In the thesis a proper model for the rheology of the granular phase, able to account for
both the regimes, is presented. This model is based on the fundamental evidence that the granular phase is characterized by the coexistence of the collisional regime, which dominates near the free surface, and of the frictional
regime, which becomes relevant approaching the loose static bed Armanini et al. [5]. The kinetic theories of dense gases Jenkins and Savage [48] are adopted to describe the collisional regime, while for the frictional regime a
new rheological formulation, dependent on the Savage number, which comes from the analysis of the force involved, is given. In addition, the model, named heuristic model [11], introduces a specific equation of state also for
the frictional regime. The model is based only on a single parameter, which presumably depends on the properties of the contact forces of the material. A numerical code able to integrate the equations of the mass, momentum and energy of the two-phase, in uniform flow conditions, was developed by Armanini et al. [6] and the results are compared with the experimental data.
In the applications to hyperconcentrated channel flows the effect of the side walls and of the internal stresses of the liquid phase are neglected in the momentum balance equations, therefore the drag force is balanced by the weight of the liquid phase. The heuristic model is able to predict in a satisfactory way the distributions across the flow depth of the velocity, concentration, granular temperature and stresses and in particular, it allows to discriminate between the collisional and the frictional components of the shear and of the normal stresses.
Another important issue addressed in the thesis concerns the balances of the energy of the granular phase. The model is able to describe the mechanisms of production, diffusion and dissipation of energy, relevant to both the mean component of the flow and the fluctuating component (i.e., the collisional component). In uniform flow conditions, near the static loose bed, the model predicts that the flux of the diffused fluctuating energy exceeds an order of magnitude the locally dissipated flux of fluctuating energy. This suggests that the motion of the grains, even at concentrations close to that of packing, is always accompanied by a certain degree of granular temperature as already observed by Armanini et al. [10].
Furthermore, the description of the mechanisms of exchange among the terms of the total energy balance and of the kinetic energy balance, and between the two energy balances is given. In the thesis, the role of the interaction between the liquid and the solid phase in the kinetic energy balance is analysed [59]. A specific experimental investigation to understand the difference between the drag averaged over time and the drag calculated with respect the average velocities and concentration is carried out. This difference between the two drags represents the contribution to the drag due to the correlations between the fluctuating components of the concentration and of the velocities. By integrating the heuristic model across the flow depth, it is possible, in principle, to derive a set of shallow water equations that are able to describe the behaviour of debris flows and wet avalanches
Innovation and Knowledge: An Explorative Study of Entrepreneurial Firms in Germany
No full textEntrepreneurial firms are considered to be vehicles for employment and growth and as such have become targets for public policy measures in all OECD countries. At the same time there is a lack of micro-level data about these firms, their characteristics, innovation activity, relationships with external sources of knowledge, links with universities, and the role of the entrepreneur in these, which renders public policy analysis difficult. Entrepreneurial firms, following the definition applied in this thesis, have as business foundation purpose the implementation of a radical innovation, and are characterised by an initial lack of existing repository of knowledge and capabilities, and a continuity of their innovation activity. From an exploratory study of 86 entrepreneurial firms, located in the metropolitan areas of Munich and Berlin, and elsewhere in Germany, we found evidence of the dominant presence of the entrepreneur in organising the firm’s innovation activity and in setting the search scope and the repertoire of external knowledge sources. Firms were undertaking multiple innovation projects in parallel, and firm characteristics, such as organisation in subunits, and multiple teams R&D teams spread across the firm, were found to positively influence the combination of new and incremental innovation projects. Firms selectively involved external sources of knowledge in their innovation activity, with involvement in new innovation projects being more frequent than in incremental projects. We found evidence that relationships between firms and universities and other public research organisations differ from inter-firm and market relationships in that the former exhibit a much higher degree of creativity, novelty and reconfiguration. Young firms, in overcoming the double-constraint of organisational and environmental factors were active networkers and likely to revert to the entrepreneur’s own networks to circumvent entry and establishment barriers in existing networks. For this, contacts maintained with the entrepreneur’s alma mater were found to be of salient relevance. We argued that science is organised in epistemic communities, which are built upon shared identities, and in which members share the same tacit and experiential knowledge, which is passed on through personal contacts, eliminating and punishing opportunistic behaviour. We found evidence that membership in these epistemic communities has lasting effects in that members will turn to other members as part of their search for related or new knowledge