1,356 research outputs found
Long-Range Dependence in Financial Markets: a Moving Average Cluster Entropy Approach
A perspective is taken on the intangible complexity of economic and social
systems by investigating the underlying dynamical processes that produce, store
and transmit information in financial time series in terms of the
\textit{moving average cluster entropy}. An extensive analysis has evidenced
market and horizon dependence of the \textit{moving average cluster entropy} in
real world financial assets. The origin of the behavior is scrutinized by
applying the \textit{moving average cluster entropy} approach to long-range
correlated stochastic processes as the Autoregressive Fractionally Integrated
Moving Average (ARFIMA) and Fractional Brownian motion (FBM). To that end, an
extensive set of series is generated with a broad range of values of the Hurst
exponent and of the autoregressive, differencing and moving average
parameters . A systematic relation between \textit{moving average
cluster entropy}, \textit{Market Dynamic Index} and long-range correlation
parameters , is observed. This study shows that the characteristic
behaviour exhibited by the horizon dependence of the cluster entropy is related
to long-range positive correlation in financial markets. Specifically, long
range positively correlated ARFIMA processes with differencing parameter , and are consistent with
\textit{moving average cluster entropy} results obtained in time series of
DJIA, S\&P500 and NASDAQ
Chemistry through tattoo inks: a multilevel approach to a practice on the rise for eliciting interest in chemical education
Within the framework of a nationwide project to boost studentsâ
enrollment in scientific disciplines in Italy, a multilevel science project was
designed with a focus on the chemistry of tattoo inks, offering immediate
connection with 16â18 year-old high school students. The approach takes into
account time constraints, since all sessions have a maximum span of 8 h, and the
heterogeneity of the audience, made up of students without background
restrictions. Tattoos are perceived as a form of body art and can be conveniently
used as the âAâ in the STEAM (science, technology, engineering, art, and
mathematics) methodology. The project involved active lectures and guided
inquiry into the simple chemical concepts related to tattoo inks, addressed in
practical units with multioutcome experiments and comparative instrumental
analysis. The connections with correlated issues, such as norms regarding tattoo
ink composition and verification, were also discussed. The efficacy of the tattoo ink
Scientific Degree Plan experience was then evaluated through two types of surveys: one on the enjoyment of the plan and the other
on mastery of the chemical concepts at the end of the experience
New insights into the structure of glycols and derivatives: a comparative X-ray diffraction, Raman and molecular dynamics study of ethane-1,2-diol, 2-methoxyethan-1-ol and 1,2-dimethoxy ethane
In this study, we report a detailed experimental and theoretical investigation of three glycol derivatives, namely ethane-1,2-diol, 2-methoxyethan-1-ol and 1,2-dimethoxy ethane. For the first time, the X-ray spectra of the latter two liquids was measured at room temperature, and they were compared with the newly measured spectrum of ethane-1,2-diol. The experimental diffraction patterns were interpreted very satisfactorily with molecular dynamics calculations, and suggest that in liquid ethane-1,2-diol most molecules are found in gauche conformation, with intramolecular hydrogen bonds between the two hydroxyl groups. Intramolecular H-bonds are established in the mono-alkylated diol, but the interaction is weaker. The EDXD study also evidences strong intermolecular hydrogen-bond interactions, with short O¡¡¡O correlations in both systems, while longer methyl-methyl interactions are found in 1,2-dimethoxy ethane. X-ray studies are complemented by micro Raman investigations at room temperature and at 80 °C, that confirm the conformational analysis predicted by X-ray experiments and simulations
Highly specific silver ion detection by fluorescent carbon quantum dots
Nitrogen-doped carbon quantum dots are easily obtainable nanomaterials endowed with remarkable fluorescence properties for the detection of contaminations by heavy metals. In this report, we show that nanometric particles with high specificity for silver cations can be prepared by hydrothermal synthesis starting from citric and folic acid solutions. Solutions of these N-CQDs give a strong fluorescence emission in the violet region (385 nm) when excited at 330 nm, which can be quenched selectively by silver (I) cations at sub-nanomolar concentrations, while other cations do not give any effect. This remarkable feature was tentatively correlated with the stronger interactions between silver ion and small portions of the nanomaterial surface by comparing Ag+ and the isoelectronic Cd2
Type 2 Diabetes Mellitus, Platelet Activation and Alzheimer's Disease: A Possible Connection
: Type 2 diabetes mellitus DM (T2DM) is associated with a 70% increased risk for dementia, including Alzheimer's disease (AD). Insulin resistance has been proposed to play a pivotal role in both T2DM and AD and the concept of "brain insulin resistance" has been suggested as an interpretation to the growing literature regarding cognitive impairment and T2DM. Subjects with T2DM present an abnormal platelet reactivity that together with insulin resistance, hyperglycaemia and dyslipidaemia effect the vascular wall by a series of events including endothelial dysfunction, oxidative stress and low-grade inflammation. Activated platelets directly contribute to cerebral amyloid angiopathy (CAA) by promoting the formation of β-amyloid (Aβ) aggregates and that Aβ, in turn, activates platelets, creating a feed-forward loop suggesting the involvement of platelets in the AD pathogenesis. Moreover, islet amyloid polypeptide deposition, co-localized with Aβ deposits, is a common finding in the brain of patients with T2DM. These observations raise the intriguing prospect that traditional or novel antiplatelet therapeutic strategies may alleviate fibril formation and could be used in the prevention or treatment of AD subjects with diabetes
ZnAl-SO4 Layered Double Hydroxide and Allophane for Cr(VI), Cu(II) and Fe(III) Adsorption in Wastewater: Structure Comparison and Synergistic Effects
Owing to their structure, layered double hydroxides (LDHs) and allophane are nowadays
considered as promising materials for application in different fields. The goal of this work is to
compare the efficacy of allophane and ZnAl-SO4 LDH to remove, by adsorption, some cationic and
anionic pollutants from industrial wastewater. Both compounds were synthesized via the coprecipitation
route (direct method) followed by hydrothermal treatment, obtaining nanoscopic
crystallites with a partially disordered turbostratic (ZnAl-SO4 LDH) or amorphous (allophane)
structure. The characterization of the obtained compounds was performed by means of powder xray
diffraction (PXRD), thermal gravimetry analysis (TGA), field emission scanning electron
microscopy analysis (FESEM), and Fourier-transform infrared spectroscopy (FT-IR). The sorbents
were tested using wastewater produced by a real metalworking plant and containing ionic species
such as Cu(II), Fe(III) and Cr(VI), whose concentration was measured by means of inductively
coupled plasma-optical emission spectrometry (ICP-OES). This investigation represents an
alternative procedure with respect to standard protocols based on customarily made and artificially
lab-produced wastewaters. Both sorbents and their combination proved to be efficient in Cr(VI)
removal, irrespective of the presence of cations like Cu(II) and Fe(III). A synergistic effect was
detected for Cu(II) adsorption in a mixed allophane/LDH sorbent, leading to a Cu(II) removal rate
of 89.5%
NOVEL SYNTHESIS OF METAL OXIDE NANOPARTICLES FROM TYPE IV DEEP EUTECTIC SOLVENTS
One of the fields where DES show remarkable added-values is the synthesis of inorganic
materials, in particular nanoparticles. In this field, the inherent and highly-tunable nano homogeneities of DES structure give origin to a marked templating effect, a precious role that
has led to the recent bloom of a vast number of studies exploiting these new synthesis media to
prepare nanomaterials and composite structures of various kinds. In this contribution, the most
recent developments in the field will be reviewed and some exciting examples of novel metal
oxide nanoparticles syntheses using non-toxic type-IV Deep Eutectic Solvents will be
described. The prepared materials possess nanometric dimensions and show flower-like/thin layered shapes. Use of the prepared nanoparticles as fluorescent materials for the detection of
various contaminants is under development
Hb Vila Real [beta36(C2)ProÂŽHis] in Italy: characterization of the amino acid substitution and the DNA mutation
A rare high oxygen affinity hemoglobin variant was identified in a 22-year-old male patient from Napoli (Naples, Italy) affected by erythrocytosis. A detailed structural characterization of the variant hemoglobin was carried out, both at the protein and DNA levels essentially by mass spectrometric procedures and allele-specific amplification techniques. The amino acid substitution was determined by liquid chromatography tandem mass spectrometric analysis of the tryptic digest as β36(C2)Pro â His; the corresponding DNA mutation was identified as C â A at the second position of codon 36 of the β chain (CCT â CAT). These variations identified the presence of Hb Vila Real, described only once before in a Portuguese woman. Haplotype analysis of DNA polymorphisms showed that the β-globin gene of Hb Vila Real was associated with haplotype I
Analisi G.I.S. per l'individuazione di zone di stress ambientale in aree protette
I processi di urbanizzazione causano notevoli danni allâambiente anche a causa della riduzione degli spazi vitali per le popolazioni animali e vegetali autoctone, che sono legate ad un particolare ambiente in grado di garantire loro la sopravvivenza. Tale riduzione si tramuta infatti in degradazione, frammentazione o perfino perdita degli habitat, con conseguente isolamento tra le specie.
Nel presente studio, localizzato allâinterno del Parco Nazionale Appennino Lucano â Val DâAgri Lagonegrese, attraverso analisi dei trend storici di uso del suolo, allâindividuazione dei vari habitat e dei loro indici di frammentazione, sono state valutate le svariate incongruenze con il sistema antropico dellâarea in esame, individuando le possibili zone di stress ambientale.
La scelta dellâarea di studio è scaturita analizzando il forte contrasto tra quella che negli anni â50 era una zona marginale e con vocazione naturalistica allâattuale zona a forte connotazione antropica come dimostrano sia il bacino articificiale della diga del Pertusillo nato agli inizi degli anni â60 (che ha dato il via ad un forte sviluppo della zootecnia e delle colture intensive) che le aree industriali sorte in relazione allo sviluppo delle politiche di estrazione del petrolio (quale, in particolare, il centro oli sito nel comune di Viggiano)
Functionalization of gold nanoparticles with Ru-porphyrin and their selectivity in the oligomerization of alkynes
Gold nanoparticles (AuNPs) were functionalized by ruthenium porphyrins through a
sulfur/gold covalent bond using a three-steps reaction. The catalyst was characterized by scanning
electron microscopy (SEM) and thermogravimetric analysis (TGA) in order to control the binding
of ruthenium porphyrin on AuNPsâ surface. The catalyst was tested and compared with an analog
system not bound to AuNPs in the oligomerization reaction using 1-phenylacetylene as the substrate
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