6,289 research outputs found
Sachs' free data in real connection variables
We discuss the Hamiltonian dynamics of general relativity with real
connection variables on a null foliation, and use the Newman-Penrose formalism
to shed light on the geometric meaning of the various constraints. We identify
the equivalent of Sachs' constraint-free initial data as projections of
connection components related to null rotations, i.e. the translational part of
the ISO(2) group stabilising the internal null direction soldered to the
hypersurface. A pair of second-class constraints reduces these connection
components to the shear of a null geodesic congruence, thus establishing
equivalence with the second-order formalism, which we show in details at the
level of symplectic potentials. A special feature of the first-order
formulation is that Sachs' propagating equations for the shear, away from the
initial hypersurface, are turned into tertiary constraints; their role is to
preserve the relation between connection and shear under retarded time
evolution. The conversion of wave-like propagating equations into constraints
is possible thanks to an algebraic Bianchi identity; the same one that allows
one to describe the radiative data at future null infinity in terms of a shear
of a (non-geodesic) asymptotic null vector field in the physical spacetime.
Finally, we compute the modification to the spin coefficients and the null
congruence in the presence of torsion.Comment: 23 pages + Appendix, 2 figures. v2: Improved text and some amendments
throughout, added more details on the relation between 2+2 foliations and
null tetrads, updated references. Version submitted for peer reviewing. v3:
Few minor amendments, footnote added on a null congruence in the presence of
torsion; matches published versio
Responsible Research and Innovation between \u201cnew governance\u201d and fundamental rights
This chapter frames RRI as an emerging governance approach in the EU regulatory context. We argue that reference to fundamental rights makes RRI a distinctive approach to responsibility compared to other existing paradigms and that human rights, in particular those laid down in the Charter of Fundamental Rights of the European Union, are not necessarily a constraint but can instead be a catalyst of innovation. Eventually we maintain that a governance framework based on the complementarity between legal norms and voluntary commitments might successfully combine the respect of fundamental rights with the openness and flexibility of the innovation process
Modelling Private Wealth Accumulation and Spend-down in the Italian Microsimulation Model CAPP_DYN: A Life-Cycle Approach
In microsimulation literature a limited number of
models include a module aimed
at analyzing and projecting the evolution of privat
e wealth over time. However, this issue appears
crucial in order to comprehensively evaluate the li
kely distributional effects of institutional
reforms adopted to cope with population ageing. In
this work we describe the implementation in
the Italian dynamic micro simulation model CAPP_DYN
of a new module in which households\u2019
savings and asset allocation are modelled. In parti
cular, we aim to account for possible
behavioural responses to pension reforms in househo
ld savings. To this end, we rely on an
approximate life cycle structural framework for est
imating saving behaviour, while adopting a
traditional stochastic micro simulation approach fo
r asset allocation. In line with Ando and
Nicoletti Altimari (2004), we emphasize the role of
lifetime economic resources in households\u2019
consumption decisions, yet we further account for i
nternal habit formation and subjective
expectations on pension outcomes in the econometric
stage. In addition, we model
intergenerational transfers of private wealth in a
probabilistic fashio
Probing Gravitational Lensing of the CMB with SDSS-IV Quasars
We study the cross-correlation between the Planck CMB lensing convergence map
and the eBOSS quasar overdensity obtained from the Sloan Digital Sky Survey
(SDSS) IV, in the redshift range . We detect the CMB lensing
convergence-quasar cross power spectrum at significance. The cross
power spectrum provides a quasar clustering bias measurement that is expected
to be particularly robust against systematic effects. The redshift distribution
of the quasar sample has a median redshift , and an effective
redshift about . The best fit bias of the quasar sample is , corresponding to a host halo mass of . This is broadly
consistent with the previous literature on quasars with a similar redshift
range and selection. Since our constraint on the bias comes from the
cross-correlation between quasars and CMB lensing, we expect it to be robust to
a wide range of possible systematic effects that may contaminate the auto
correlation of quasars. We checked for a number of systematic effects from both
CMB lensing and quasar overdensity, and found that all systematics are
consistent with null within . The data is not sensitive to a possible
scale dependence of the bias at present, but we expect that as the number of
quasars increases (in future surveys such as DESI), it is likely that strong
constraints on the scale dependence of the bias can be obtained.Comment: 8 pages, 6 figures, 1 table; matches published version on MNRA
The Introduction of a Private Wealth Module in CAPP_DYN: an Overview
Household saving rate in Italy declined over the last two decades.This trend still persists despite three pension reforms have been enacted since the beginning of the nineties. In this paper we search further evidence of general macroeconomic effects through the analysis of households behaviour. In the first part of the paper we use data from five surveys of the Bank of Italy Surveys of Household Income and Wealth (SHIW) to estimate the lifetime profiles of saving and wealth accumulation. Estimates show that the age profile of the propensity to save has been influenced more by cohort effects than by general trend effects; whereas the age profile of the ratios of financial assets to disposable income has been subject to relevant trend effects. In the second part of the paper we analyse the effects of pension reforms on saving behaviour of Italian Households. Firstly we use a difference-in-difference estimator in order to test whether the groups more severely hit by the reforms actually increased their saving rate relative to the other groups. Then we estimate the Social Security Net Wealth (SSWN) for each individual in the SHIW in the analysed period (1989-2000). Finally we estimate the substitution coefficient between SSWN and private wealth taking into account that the reaction of saving to a change in SSWN depends also on age of the individual. Our results show that the reduction of SSWN is unequally distributed across individuals. The cut is stronger for self employed, young workers and women. Most of the groups more severely hit by the reforms did not increase their saving rate relative to the control group: younger households, in particular, did not increase the saving rate. On the whole a reduction of one Euro in SSWN seems to induce, on the average, a compensating increase in private wealth by about fifty cents. The substitution coefficient between private and social security wealth is higher for the richest and oldest part of the sample. Finally when we split the sample observations by year we find that the more dramatised is the impact of the reform, the higher is the substitution coefficient.Pension reform; household saving; social security wealth; difference-in-difference
Gestione delle acque in una raffineria di olio vegetale
Il presente lavoro di tesi ha come obiettivo primario la definizione qualitativa e quantitativa delle correnti di acqua utilizzate nella raffineria di olio alimentare Salov s.p.a.
In secondo luogo si definiscono alcune modifiche al processo produttivo, e alcune semplici soluzioni impiantistiche per la riduzione dei consumi di acqua.
Infine si analizza l'impianto di trattamento di acque reflue dello stabilimento proponendo eventuali miglioramenti
Application of process analytical technology (PAT) tools for the better understanding and control of the crystallization of polymorphic and impure systems
This work presents a comprehensive study on the application of PAT tools to study, monitor and control polymorphism during batch cooling crystallization processes. For the first time, the same techniques were used to control and adjust polymorphic purity of the solid phase but also to investigate the relation between chemical equilibrium in solution and polymorphic outcome of cooling crystallization.
Crystallization is an important unit operation used as separation and purification technique. It is widely employed in the pharmaceutical, chemical, agrochemical, food and cosmetics industries but also in the electronic, metallurgic and material industries. More than 90% of the APIs on the market are produced by crystallization, therefore, monitoring and control this process is fundamental to ensure the quality of the final product. The implementation of process analytical technology (PAT) tools during the development stage of APIs has largely helped in better understanding and optimizing both batch and, more recently, continuous crystallization.
Polymorphism is the capacity of a compound to crystallize in more than one different crystalline structure, which can have different properties such as density, melting point, bioavailability and solubility. The choice of solvent, pH, kinetic conditions and presence of impurities has very strong effect on the polymorphic outcome of a cooling crystallization in solution. Understanding this phenomenon as well as being able to monitor and control it during industrial crystallization is one the biggest challenges for pharmaceutical industries
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