118,530 research outputs found
An overview of blockchain-based systems and smart contracts for digital coupons
No full textAmong the accessory applications of the blockchain, the idea of using it as an immutable register for tracking and certifying documents is recently gaining interest in research and industry. The problems of traceability, non-counterfeiting and unique usage of digital coupons fall within this area; many couponing platforms are hence exploring the possibility of addressing the above limitations with blockchain technologies. In view of the foregoing, in this work we analyse and compare several blockchain-based couponing systems. To do so, we first propose a general schema of digital coupon and define the desirable properties of a couponing system. Then, we select a sample of these systems and we examine them, describing their design choices and summarizing their relevant properties. Finally, we inspect their code and study how the notion of couponing system is interpreted in their smart contracts. We also highlight their distinctive features and relevant implementation solutions. We conclude by discussing what emerged from our analysis and proposing some possible future investigations
Cholesterol metabolism in primary biliary cirrhosis during simvastatin and UDCA administration
No full textLittle is known about the effects of cholesterol-lowering agents in hypercholesterolemic patients with primary biliary cirrhosis (PBC). The aim of this study was to compare the changes induced by simvastatin and ursodeoxycholic acid (UDCA) on cholesterol metabolism in patients with PBC and preserved liver function. Six patients with PBC were administered simvastatin (40 mg/day) for 30 days and, after a washout period of 30 days, ursodeoxycholic acid (600 mg/day) for 30 days. Serum levels of lathosterol, campesterol, 7 alpha-hydroxycholesterol, and 27-hydroxycholesterol were measured by gas chromatography-mass spectrometry. During simvastatin administration, reduction of cholesterol levels (34% in 30 days) was paralleled by the decrease of lathosterol (55%), whereas concentrations of campesterol and of the two hydroxysterols were not substantially modified. During ursodeoxycholic acid administration, a trend toward a decrease of serum cholesterol concentrations was observed after only one year of treatment, and these changes were paralleled by the decrease of campesterol serum levels. Both simvastatin and UDCA were well tolerated, and a reduction of serum liver enzyme levels occurred with the latter. Simvastatin proved to be safe and effective in reducing serum cholesterol levels in patients with PBC by an inhibitory effect on cholesterol synthesis occurring within 24 h. --Del Puppo, M., M. Galli Kienle, A. Crosignani, M. L. Petroni, B. Amati, M. Zuin, and M. Podda. Cholesterol metabolism in primary biliary cirrhosis during simvastatin and UDCA administration. J. Lipid Res. 2001. 42: 437--441
Data Protection and Rule of Law: A Challenging Perspective
No full textEvery person has the right to a legal identity, the right to recognition as a person before the law, enabling that person to assert rights, enforce contracts, assert or defend a case in court. This right is freestanding thus, not dependent on official identification, and it has been recognized and codified in different international human rights treaties (UDHR in 1948, ICCPR), and in the modern Constitutions. However, in today’s globalized world, there is an increase in linking access to services such as health, education, etc., to possession of several form of identification that, while collecting evidence of people life events, grant them digital identity. To this aim, the most advanced technological tools are used to solve the challenges of traditional weak identification systems and, relying on modern technology, several forms of identification have been presented, studied and still implemented (Allen, C. 2016). In most developed countries, this approach follows the scrutiny of democratic institutions, committees and boards, raising questions linked to de-anonymization problems and focused on privacy and data protections. Concerning less developed countries, some authors (Johnston, S.F. 2018) argue that technology seems to represent a “technological fix” thus, a generic tool for circumventing problems commonly conceived as social, political or cultural. In these contexts, indeed, these systems certainly represents a valuable tool for granting civil rights, but also represents a valuable source of statistics, used as a key tool for shaping public interventions and allowing policy making based on forecasting, for monitoring new trends and planning feasible policies (UN Data Revolution for Sustainable Development, 2014). Often, in such contexts, the rule of law is weak and data collected with technological systems of identification can be misused, leading not only to a greater concentration of power in the hands of non-governmental organizations, but also to complex relationships between asymmetric information and power (Khan & Roy, 2019). It emerges the need of brainstorming on whether group privacy (Taylor, L., van der Sloot, B., and Floridi, L. 2017) remains the main problem, or whether new scenario can emerge, primarily depending on local context and local perception
Environmental mineralogy in the mining area of Montevecchio Ponente (SW Sardinia)
No full textThe Montevecchio mining area (Arbus – Guspini, Sardinia SW) has been exploited for centuries, for the
extraction of lead and zinc minerals.
The following work focuses on the study and characterization of the sources and contaminants present in
the “Cantieri Sanna” from the area of Montevecchio Ponente.
There is a large amount of mining residues in the area downstream of the washing plants, affected by
important erosion phenomena, which involve a solid transport of contaminants in solution.
These mineral residues were characterized by diffractometric (XRD) and chemical analysis (ICP-MS), after
their solubilization. The whitish biomineral patinas present along the Rio Roia Cani were also analyzed by
means of diffractometric analysis and a scanning electron microscope (SEM).
From the analysis carried out, the presence of secondary phases emerged, such as: epsomite, glaucocerinite,
goethite, hydroxyapatite, minium, nantokite, plumbojarosite and zincite, indicating a remarkable reactivity
of the tailings with atmospheric agents; these results made it possible to identify tailings as a source of
contamination. Furthermore, the presence of sub-economic contents of rare earths elements (REE), more
particularly of light rare earths elements (LREE), and of Al, Fe, Pb and Zn emerged.
Biomineralization occurs in the area was found in the streambed of rio Roja Cani; it appears like that which
forms in the bed of the rio Naracauli, described in detail in Medas et al. (2014).
SEM-EDS analysis confirm that biomineralization is mediated by bacterial activity, due to the filamentous
and tubular structures present in biofilms; furthermore, the presence of zinc and oxygen emerges from the
compositional maps, confirming that the biomineralization is composed of hydrozincite, as revealed by the
XRD analysis.
We argued that this biomineralization rules natural attenuation of zinc as already found in rio Naracauli
(Wanty et al., 2013; De Giudici et al., 2014)
Il corso integrato di Metodologia clinica : sua sperimentazione e valutazione presso il Polo S. Paolo di Milano
No full text
The pollination biology to study biological structure of natural populations
No full textWe studied the pollination biology of some species of Faboideae, with special attention to the pollination mechanisms. We calculated the pollen/ovule ratio (P/O) to obtain indirect information about breeding system and efficiency of pollen transfer. We calculated correlation between quantitative characters: P(total number of pollen grains per flower), O (total number of ovule per flower), P/O (Pollen/Ovule ratio), V (volume of single pollen grain), Vtot (total volume of pollen per flower) and flower dry weight (size of flower), to assess the energy investment in reproduction. All species resulted xenogamus. The pollination mechanism didn't result correlated either with taxonomic position of species, or with P/O ratio.There is no trade-off between number and volume of pollen grains, while a positive correlation has been verified between: P and O; flower size and volume of single pollen grain and flower size and total volume of pollen
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