262 research outputs found

    Technological change and the demand for currency: An analysis with household data

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    Advances in transaction technology allow agents to economize on the cost of cash management. We argue that accounting for the impact of new transaction technologies on currency holding behaviour is important to obtain theoretically consistent estimates of the demand for money. We modify a standard inventory model to study the effect of withdrawal technology on the demand for currency. An empirical specification for households’ demand schedule is suggested, in which both the level of currency holdings and the interest rate elasticity of demand depend on the withdrawal technology available to agents (e.g. ATM card ownership or a high/low density of bank branches, ATMs). The theoretical implications are tested using a unique panel of Italian household data (on currency holdings, deposit interest rates, consumption, development of banking services, etc.) for the period 1989-2004.money demand, inventory models, technological change

    The Demand for Currency at Low Interest Rates

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    currency, search theory, inflation

    The Wall-Jet Region of a Turbulent Jet Impinging on Smooth and Rough Plates

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    The study reports direct numerical simulations of a turbulent jet impinging onto smooth and rough surfaces at Reynolds number Re = 10,000 (based on the jet mean bulk velocity and diameter). Surface roughness is included in the simulations using an immersed boundary method. The deflection of the flow after jet impingement generates a radial wall-jet that develops parallel to the mean plate surface. The wall-jet is structured into an inner and an outer layer that, in the limit of infinite local Reynolds number, resemble a turbulent boundary layer and a free-shear flow. The investigation assesses the self-similar character of the mean radial velocity and Reynolds stresses profiles scaled by inner and outer layer units for varying size of the roughness topography. Namely the usual viscous units uτu_{\tau} and δυ\delta_{\upsilon} are used as inner layer scales, while the maximum radial velocity umu_{m} and its wall-normal location zmz_{m} are used as outer layer scales. It is shown that the self-similarity of the mean radial velocity profiles scaled by outer layer units is marginally affected by the span of roughness topographies investigated, as outer layer velocity and length reference scales do not show a significantly modified behavior when surface roughness is considered. On the other hand, the mean radial velocity profiles scaled by inner layer units show a considerable scatter, as the roughness sub-layer determined by the considered roughness topographies extends up to the outer layer of the wall-jet. Nevertheless, the similar character of the velocity profiles appears to be conserved despite the profound impact of surface roughness

    Heat Transfer of an Impinging JET : Sensitivity Towards Inflow Conditions

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    The wall-heat transfer in the impingement region of a turbulent incompressible jet impinging onto a flat plate is assessed using direct numerical simulations. For impinging jets, the mean wall-heat transfer distribution along the plate features a global maximum close to the jet axis and, for specific configurations, a secondary peak further downstream of the impingement region. While the appearance of the latter maximum has been the focus of many investigations, the occurrence of the former and its links to the inflow conditions of the jet have only been alluded to by existing studies. The present research considers two different inflow conditions: a fully developed turbulent pipe flow and a slightly convergent nozzle. The study shows that turbulent fluctuations, characterising the impingement region of the fully-developed turbulent inflow case, are significant in determining events of positive wall-heat transfer rates very close to the jet axis. On the contrary, similar events are not observed in the stagnation region of the convergent nozzle case, and the associated mean wall-heat transfer displays a markedly different distribution compared to the fully- developed turbulent inflow case

    DNS of Turbulent Impinging JETS on rough surfaces using a parametric forcing Approach

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    This work presents direct numerical simulations (DNS) of a circular turbulent jet impinging on rough plates. A parametric forcing approach (PFA) accounts for surface roughness effects by applying a forcing term into the Navier-Stokes equations within a thin layer in the near-wall region. The application of the PFA in the context of spatially developing flows is the essential aspect of the investigation. The method is known to produce accurate predictions of the velocity field in fully developed turbulent flows while avoiding the demanding grid resolution required by an immersed boundary method (IBM) approach. The comparison between PFA results and IBM-resolved roughness DNS allows addressing the advantages and limitations of the PFA in the context of spatially developing flows

    Heparanase and macrophage interplay in the onset of liver fibrosis

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    Abstract The heparan sulfate endoglycosidase heparanase (HPSE) is involved in tumor growth, chronic inflammation and fibrosis. Since a role for HPSE in chronic liver disease has not been demonstrated to date, the current study was aimed at investigating the involvement of HPSE in the pathogenesis of chronic liver injury. Herein, we revealed that HPSE expression increased in mouse livers after carbon tetrachloride (CCl4)-mediated chronic induction of fibrosis, but with a trend to decline during progression of the disease. In mouse fibrotic liver tissues HPSE immunostaining was restricted in necro-inflammatory areas, co-localizing with F4/80 macrophage marker and TNF-α. TNF-α treatment induced HPSE expression as well as HPSE secretion in U937 macrophages. Moreover, macrophage-secreted HPSE regulated the expression of α-SMA and fibronectin in hepatic stellate LX-2 cells. Finally, HPSE activity increased in the plasma of patients with liver fibrosis but it inversely correlated with liver stiffness. Our results suggest the involvement of HPSE in early phases of reaction to liver damage and inflammatory macrophages as an important source of HPSE. HPSE seems to play a key role in the macrophage-mediated activation of hepatic stellate cells (HSCs), thus suggesting that HPSE targeting could be a new therapeutic option in the treatment of liver fibrosis

    Una strada parco per la "CittĂ  Pontina"

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    Nel volume è presentato un progetto di parco lineare innervato sulla realizzazione di una pista ciclabile che sfrutta il tracciato ferroviario dismesso della tratta Velletri Terracina. Il parco include aree agricole, siti archeologici e di interesse storico e naturalistico ed una serie di cave dismesse di cui si progetta la rinaturalizzazioned il riuso per servizi del parco. Il progetto prevede inoltre risalite meccaniche ai centri antichi sulla Pedemontana Setina.In this volume is presented a draft innervated linear park on the creation of a bike path that takes advantage of the disused railway line is of Velletri Terracina. The park includes agricultural areas, and archaeological sites of historical and natural interest and a series of disused quarries where you plan to reuse the rinaturalizzazioned for park services. The project also includes the ski lifts to the ancient centers on the foothills Setina

    Turbulent impinging jets on rough surfaces

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    This work presents direct numerical simulations (DNS) of a circular turbulent jet impinging on rough plates. The roughness is once resolved through an immersed boundary method (IBM) and once modeled through a parametric forcing approach (PFA) which accounts for surface roughness effects by applying a forcing term into the Navier–Stokes equations within a thin layer in the near-wall region. The DNS with the IBM setup is validated using optical flow field measurements over a smooth and a rough plate with similar statistical surface properties. In the study, IBM-resolved cases are used to show that the PFA is capable of reproducing mean flow features well at large wall-normal distances, while less accurate predictions are observed in the near-wall region. The demarcation between these two regions is approximately identified with the mean wall height of the surface roughness distribution. Based on the observed differences in the results between IBM- and PFA-resolved cases, plausible future improvements of the PFA are suggested

    Post-Collisional Tectonomagmatic Evolution, Crustal Reworking and Ore Genesis along a Section of the Southern Variscan Belt: The Variscan Mineral System of Sardinia (Italy)

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    Since the early Paleozoic, numerous metallogenic events produced in the Sardinian massif a singular concentration of mineral deposits of various kinds. Among them, the Variscan metallogenic peak represents a late Paleozoic phase of diffuse ore formation linked to the tectonomagmatic evolution of the Variscan chain. Twomain classes of oresmay primarily be attributed to this peak:(1)mesothermal orogenic-type As-Au ±W± Sb ores, only found in E Sardinia, and (2) intrusion-related Sn-W-Mo-F and base metals-bearing ores found in the whole Sardinian Batholith, but mainly occurring in central–south Sardinia. Both deposit classes formed diachronously during the Variscan post-compressional extension. The orogenic-type ores are related to regional-scale flows ofmineralizing fluids, and the intrusion-related ores occur around fertile intrusions of different granite suites. Metallogenic reconstructions suggest almost entirely crustal processes ofmineralizationwithout a significant contribution fromthemantle. We summarized these processes with a holistic approach and conceptualized the Sardinian Variscan Mineral System (SVMS), a crustal-scale physical system of ore mineralization in the Sardinian basement. The SVMS required suitable metal sources in the crust and diffuse crustal reworking triggered by heat that allowed (a) the redistribution of the original metal budget of the crust in magmas by partial melting and (b) the production of metal-bearing fluids by metamorphic dehydration. Heat transfer in the Sardinian Variscan crust involved shear heating in lithospheric shear zones and the role of mantle uplift as a thermal engine in an extensional tectonic setting. Lithospheric shear zones acted as effective pathways in focusing fluid flow through a large-scale plumbing system into regional-scale structural traps for ores. Pre-Variscan metal sources of metallogenic relevance may have been (1) the magmatic arc and magmatic arc-derived materials of Ordovician age, extensively documented in E Sardinia crust, and (2) an inferred Precambrian crystalline basement lying under the Phanerozoic crustal section, whose presence has been assumed from geophysical data and from petrological and geochemical characteristics of granite suites. At shallower crustal levels, important contributions of metals may have come from pre-Variscan ore sources, such as the Pb-ZnMVT Cambrian ores of SWSardinia or the REE-bearing Upper Ordovician paleoplacers of E Sardinia
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