5,595 research outputs found
On the Estimation of Euler Equations in the Presence of a Potential Regime Shift
The concept of a peso problem is formalized in terms of a linear Euler equation and a nonlinear marginal model describing the dynamics of the exogenous driving process. It is shown that, using a threshold autoregressive model as a marginal model, it is possible to produce time-varying peso premia. A Monte Carlo method and a method based on the numerical solution of integral equations are considered as tools for computing conditional future expectations in the marginal model. A Monte Carlo study illustrates the poor performance of the generalized method of moment (GMM) estimator in small and even relatively large samples. The poor performance is particularly acute in the presence of a peso problem but is also serious in the simple linear case.peso problem; Euler equations; GMM; threshold autoregressive models
Applied research by design: an experimental collaborative and interdisciplinary design charrette
This article reports on one experimental case of interdisciplinary collaboration on a design and planning exercise across several scales ā local through urban to regional ā and sectors ā private, public, scholarly, and interest groups. The case is a collaborative and interdisciplinary design charrette on sustainable urbanism for envisioning the future of the Greater Metropolitan Area of Florence in Italy. The experiment entailed the attempt to integrate complex urban conditions via the design charrette in order to create more healthy and sustainable cities. This collaborative work shows how conditions that are at times not addressed comprehensively nor holistically can be combined through doing applied research by design; where design is understood as a process of discovery and creation that results in synthesis. The article details the methodology applied, and provides an initial assessment on the process that the charrette employed. Moreover, it highlights some professional and policy implications of the effort. Finally, it provides a provisional assessment on learning outcomes and addresses opportunities to improve future exercises of this nature
The effects of reduced physical activity on the lipid profile in patients with high cardiovascular risk during covid-19 lockdown
Background: The COVID-19 pandemic is a serious global health problem. In Italy, to limit the infections, the government ordered lockdown from March 2020. This measure, designed to contain the virus, led to serious limitations on the daily life of the individuals it affected, and in particular in the limitation of physical exercise. The aim of this study was to evaluate the effects of reduced physical activity on the lipid profile in patients with high cardiovascular risk. Methods: We enrolled 38 dyslipidemic patients, 56% male, with an age range of 44ā62 years, considered to be at high cardiovascular risk. All patients were prescribed statin drug therapy (atorvastatin 40 mg) and a vigorous physical activity program four times a week, 1 h per session. In addition, a personalized Mediterranean diet was prescribed to all the patients. Total cholesterol, LDL, HDL and triglycerides were measured in patients at T0 before lockdown and at T1 during lockdown. Results: Data showed a significant increase (p < 0.01) in total cholesterol (+6,8%) and LDL (+15,8%). Furthermore, the analysis of the data revealed a reduction in HDL (ā3%) and an increase in triglycerides (+3,2%), although both were not significant (p > 0.05). Conclusions: Our study showed that the reduction in physical activity during lockdown led to an increase in LDL levels, and therefore, in the risk of ischemic heart disease in dyslipidemic patients with high cardiovascular risk
Instantaneous cell migration velocity may be ill-defined
Cell crawling is critical to biological development, homeostasis and disease.
In many cases, cell trajectories are quasi-random-walk. In vitro assays on flat
surfaces often described such quasi-random-walk cell trajectories as
approximations to a solution of a Langevin process. However, experiments show
quasi-diffusive behavior at small timescales, indicating that instantaneous
velocity and velocity autocorrelations are not well-defined. We propose to
characterize mean-squared cell displacement using a modified F\"urth equation
with three temporal and spatial regimes: short- and long-time/range diffusion
and intermediate time/range ballistic motion. This analysis collapses
mean-squared displacements of previously published experimental data onto a
single-parameter family of curves, allowing direct comparison between movement
in different cell types, and between experiments and numerical simulations. Our
method also show that robust cell-motility quantification requires an
experiment with a maximum interval between images of a few percent of the
cell-motion persistence time or less, and a duration of a few
orders-of-magnitude longer than the cell-motion persistence time or more.Comment: 5 pages, plus Supplemental materia
Cyclooxygenase Inhibition Safety and Efficacy in Inflammation-Based Psychiatric Disorders
According to the World Health Organization, the major psychiatric and neurodevelopmental disorders include major depression, bipolar disorder, schizophrenia, and autism spectrum disorder. The potential role of inflammation in the onset and progression of these disorders is increasingly being studied. The use of non-steroidal anti-inflammatory drugs (NSAIDs), well-known cyclooxygenase (COX) inhibitors, combined with first-choice specific drugs have been long investigated. The adjunctive administration of COX inhibitors to classic clinical treatments seems to improve the prognosis of people who suffer from psychiatric disorders. In this review, a broad overview of the use of COX inhibitors in the treatment of inflammation-based psychiatric disorders is provided. For this purpose, a critical analysis of the use of COX inhibitors in the last ten years of clinical trials of the major psychiatric disorders was carried out
Direct radiative effects by anthropogenic particles at a polluted site: Rome (Italy)
The direct radiative effect (DRE) by all (anthropogenic plus natural) and anthropogenic aerosols is calculated at the solar (0.3ā4 Ī¼m) and infrared (4ā200 Ī¼m) spectral range to better address the annual cycle of the anthropogenic
aerosol impact at a site (Rome, Italy) significantly affected by pollution. Aerosol optical and microphysical properties from 2003 AERONET Sun/sky-photometer
measurements and solar surface albedos based on MODIS satellite sensor data constitute the necessary input to radiative transfer simulations. Clear- and all-sky
conditions are investigated by adopting ISCCP monthly products for high-, mid-, and low-cloud cover. It is shown that monthly mean values of aerosol optical depths by anthropogenic particles (AODa) are on average more than 50% of the corresponding all-aerosol-optical-depth (AOD) monthly means. In particular, the AODa/AOD ratio that varies within the (0.51ā0.83) on autumn-winter (AW,
October-March), varies within the (0.50ā0.71) range on spring-summer (SS, April-September) as a consequence of the larger contribution of natural particles on SS. The surface (sfc), all-sky DRE by anthropogenic particles that is negative all year round at solar wavelengths, represents on average 60% and 51% of the all-sky sfc-DRE by all aerosols
on AW and SS, respectively. The all-sky atmospheric forcing by anthropogenic particles (AFa) that is positive all year round, is little dependent on seasons: it varies within the (1.0ā4.1)W/m2 and (2.0ā4.2)W/m2 range on AW and SS, respectively. Conversely, the all-sky AF by all aerosols is characterized by a marked seasonality. As a consequence, the atmospheric forcing by anthropogenic particles that on average is 50% of the AF value on AW, decreases down to 36% of the AF value on SS. Infrared aerosol DREs that are positive all year round are significantly smaller than the corresponding absolute values of solar DREs. Clouds decrease on average ToA- and sfc-DRE absolute values by anthropogenic particles of 36% and 23%, respectively and are quite responsible of the seasonal dependence of aerosol forcing efficiencies by all and anthropogenic aerosols
A simplified approach for the seismic loss assessment of rc buildings at urban scale: The case study of Potenza (Italy)
Comprehensive methodologies based on a fully probabilistic approach (i.e., the performance- based earthquake engineering approach, PBEE), represent a refined and accurate tool for the seismic performance assessment of structures. However, those procedures are suitable for building-specific evaluations, appearing extremely time-consuming if applied at the urban scale. In the proposed contribution, simplified loss assessment procedure will be applied at the urban scale with reference to the residential building stock of the center of Potenza. After the identification of the main reinforced concrete (RC) structural typologies and the definition of specific archetype building numerical models, the direct estimation of expected annual loss (DEAL) methodology will be applied to derive the EAL (i.e., expected annual loss) of RC buildings, deriving information on the effectively seismic quality (or seismic resilience) of the aforementioned built heritage at urban scale. Similarly, the monetary losses associated with downtime are evaluated. Preliminary considerations on the socio-economic effects of seismic scenarios on the territorial scale are also proposed
High brightness 100 W-50 Ī¼m delivery blue laser diode module
Blue laser diodes are emerging as the next revolution in laser material processing, especially for high reflective materials, such as copper and gold. The paper presents the most recent evolution of a family of medium-high power and high brightness devices specifically conceived for micro-machining applications. The modules make use of a proprietary architecture based on the combination of commercial laser diodes in TO9 package. The diodes are first organized in rows staggered along the fast axis, then the rows are multiplexed along the fast axis; finally, wavelength and polarization multiplexing are exploited to achieve up to 100W of power into a 50 Ī¼m/0.22NA fiber
Lead-free piezoelectrics: V3+ to V5+ ion conversion promoting the performances of V-doped Zinc Oxide
Vanadium doped ZnO (VZO) thin films were grown by RF magnetron sputtering, starting from a ZnO:V
ceramic target. The crystal structure, chemical composition, electric and piezoelectric properties of
the films were investigated either on the as-grown thin films or after a post-deposition rapid thermal
annealing (RTA) treatment performed at 600 Ā°C for different lengths of time (1 and 5 min) in an oxygen
atmosphere. Substitutional doping of Zn2+ with V3+ and V5+ ions strongly deteriorated the hexagonal
wurtzite ZnO structure of the as-grown thin films due to lattice distortion. The resulting slight
amorphization led to a poor piezoelectric response and higher resistivity. After the RTA treatment,
strong c-axis oriented VZO thin films were obtained, together with a partial conversion of the starting
V3+ ions into V5+. The improvement of the crystal structure and the stronger polarity of both V3+ ā O
and V5+ ā O chemical bonds, together with the corresponding easier rotation under the application of
an external electric field, positively affected the piezoelectric response and increased conductivity. This
was confirmed by closed-loop butterfly piezoelectric curves, by a maximum d33 piezoelectric coefficient
of 85 pmĀ·Vā1, and also by ferroelectric switching domains with a well-defined polarization hysteresis
curve, featuring a residual polarization of 12.5 Ī¼Cācmā2
foF2 prediction in Rome observatory
A prediction procedure of the hourly values of the critical frequency of the F2 ionospheric layer, foF2, based on the local geomagnetic index ak, is presented. The geomagnetic index utilised is the time-weighted accumulation magnetic index ak(Ļ) based on recent past history of the index ak. It is utilised an empirical relationship between the log(NmF2(t)/ NmF2M), where NmF2(t) is the hourly maximum electron density at the F2 peak layer and NmF2M is its 'quiet' value, and the time weighted magnetic index. The prediction of foF2 is calculated during periods of severe magnetic activity in the current solar cycle 23 in Rome observatory
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