On the definition of phase and amplitude variability in functional data analysis

We introduce a modeling and mathematical framework in which the problem of registering a functional data set can be consistently set. In detail, we show that the introduction, in a functional data analysis, of a metric/semi-metric and of a group of warping functions, with respect to which the metric/semi-metric is invariant, enables a sound and not ambiguous definition of phase and amplitude variability. Indeed, in this framework, we prove that the analysis of a registered functional data set can be re-interpreted as the analysis of a set of suitable equivalence classes associated to original functions and induced by the group of the warping functions. Moreover, an amplitude-to-total variability index is proposed. This index turns out to be useful in practical situations for measuring to what extent phase variability affects the data and for comparing the effectiveness of different registration methods.     

Uncover the predictive structure of healthcare efficiency applying a bootstrapped data envelopment analysis

One of the main problems in efficiency analysis is to determinate the environmental variables that have an impact on the production process. This paper shows that applying bootstrap to data envelopment analysis (DEA) before performing classification and regression trees (CART) increase the quality of the results. In particular, employing data on the Italian Health System, the paper highlights that bias corrected DEA allows to individuate variables affecting health efficiency which would remain undiscovered when the traditional DEA model is applied.     

Physical and chemical characterization of Pescabivona,a Sicilian white flesh peach cultivar [Prunus persica (L.) Batsch]

Pescabivona is an autochthonous white flesh peach cultivar population from Sicily. The composition of four Pescabivona peach landraces (Murtiddara, Bianca, Agostina, and Settembrina) at three different growing altitudes was studied. Color, color distance, weight, pulp firmness, pH, soluble solid content (SSC), titratable acidity (TA), SSC/TA ratio, organic acids, sugars, phenolics, antioxidant capacity, and lactone compounds were determined.In general for the analyzed parameters, univariate statistical analysis highlighted only a few significant differences among the landraces and the altitudes, thus demonstrating a general homogeneity of this local cultivar population. Principal component analysis, as well, did not show a clear separation among the different landraces, in particular for Bianca, Agostina, and Settembrina.The physico-chemical analysis showed high pulp firmness, high lactone content, and a balanced SSC/TA ratio. Moreover, even if the pulp firmness values were quite high for Agostina and Settembrina, sugar and acid content were typical of fresh-market quality peaches.     

Mycobacterial and Human Ferrous Nitrobindins: Spectroscopic and Reactivity Properties

Structural and functional properties of ferrous Mycobacterium tuberculosis (Mt-Nb) and human (Hs-Nb) nitrobindins (Nbs) were investigated. At pH 7.0 and 25.0 °C, the unliganded Fe(II) species is penta-coordinated and unlike most other hemoproteins no pH-dependence of its coordination was detected over the pH range between 2.2 and 7.0. Further, despite a very open distal side of the heme pocket (as also indicated by the vanishingly small geminate recombination of CO for both Nbs), which exposes the heme pocket to the bulk solvent, their reactivity toward ligands, such as CO and NO, is significantly slower than in most hemoproteins, envisaging either a proximal barrier for ligand binding and/or crowding of H₂O molecules in the distal side of the heme pocket which impairs ligand binding to the heme Fe-atom. On the other hand, liganded species display already at pH 7.0 and 25 °C a severe weakening (in the case of CO) and a cleavage (in the case of NO) of the proximal Fe-His bond, suggesting that the ligand-linked movement of the Fe(II) atom onto the heme plane brings about a marked lengthening of the proximal Fe-imidazole bond, eventually leading to its rupture. This structural evidence is accompanied by a marked enhancement of both ligands dissociation rate constants. As a whole, these data clearly indicate that structural–functional relationships in Nbs strongly differ from what observed in mammalian and truncated hemoproteins, suggesting that Nbs play a functional role clearly distinct from other eukaryotic and prokaryotic hemoproteins.     

Poly(vinyl chloride) hollow‐fiber membranes for ultrafiltration applications: Effects of the internal coagulant composition

Poly(vinyl chloride) (PVC) hollow‐fiber membranes were spun by a dry/wet phase‐inversion technique from dopes containing 15 wt % PVC to achieve membranes with different pore sizes for ultrafiltration (UF) applications. The effects of the N,N‐dimethylacetamide (DMAc) concentration in the internal coagulant on the structural morphology, separation performance, and mechanical properties of the produced PVC hollow fibers were investigated. The PVC membranes were characterized by scanning electron microscopy, average pore size, pore size distribution, void volume fraction measurements, and solubility parameter difference. Moreover, the UF experiments were conducted with pure water and aqueous solutions of poly(vinyl pyrrolidone) as feeds. The mechanical properties of the PVC hollow‐fiber membranes were discussed in terms of the tensile strength and Young's modulus. It was found that the PVC membrane morphology changed from thin, fingerlike macrovoids at the inner edge to fully spongelike structure with DMAc concentration in the internal coagulant. The effective pores showed a wide distribution, between 0.2 and 1.1 μm, for the membranes prepared with H₂O as the internal coagulant and a narrow distribution, between 0.114 and 0.135 μm, with 50 wt % DMAc. The results illustrate that the difference in the membrane performances was dependent on the DMAc concentration. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Development of improved PPARβ/δ inhibitors

GSK0660 (1) is the first peroxisome proliferator-activated receptor (PPAR) β/δ-selective inhibitory ligand described in the literature. Based on its structure, we designed and synthesized a series of modified compounds to establish preliminary structure-activity relationships. Most beneficial for increased binding affinity towards the PPARβ/δ ligand binding domain was the replacement of the 4'-aminophenyl substituent by medium-length n-alkyl chains, such as n-butyl or iso-pentyl. These compounds show activity down to the one-digit nanomolar range, thus possessing up to a tenfold higher binding affinity compared with GSK0660. Additionally, the subtype-specific inhibition of PPARβ/δ was confirmed in a cell-based assay making these compounds invaluable tools for the further exploration of the functions of PPARβ/δ.     

Optimal design of capacitated production networks

In this work we present a mixed-integer model for the optimal design of production/transportation systems. In contrast to standard design problems, our model is originally based on a coupled system of differential equations capturing the dynamics of manufacturing processes and stocks. The problem is to select an optimal parameter configuration from a predefined set such that respective constraints are fulfilled. We focus on single commodity flows over large time scales as well as highly interconnected networks and propose a suitable start heuristic to ensure feasibility and to speed up the solution procedure.     

Ordered mesoporous α-Fe2O3 (hematite) thin-film electrodes for application in high rate rechargeable lithium batteries

Herein is reported the synthesis of ordered mesoporous α-Fe(2)O(3) thin films produced through coassembly strategies using a poly(ethylene-co-butylene)-block-poly(ethylene oxide) diblock copolymer as the structure-directing agent and hydrated ferric nitrate as the molecular precursor. The sol-gel derived α-Fe(2)O(3) materials are highly crystalline after removal of the organic template and the nanoscale porosity can be retained up to annealing temperatures of 600 °C. While this paper focuses on the characterization of these materials using various state-of-the-art techniques, including grazing-incidence small-angle X-ray scattering, time-of-flight secondary ion mass spectrometry, X-ray photoelectron spectroscopy, and UV-vis and Raman spectroscopy, the electrochemical properties are also examined and it is demonstrated that mesoporous α-Fe(2)O(3) thin-film electrodes not only exhibit enhanced lithium-ion storage capabilities compared to bulk materials but also show excellent cycling stabilities by suppressing the irreversible phase transformations that are observed in microcrystalline α-Fe(2)O(3).     

Extending timescales and narrowing linewidths in NMR

Among the different fields of research in nuclear magnetic resonance (NMR) which are currently investigated in the Laboratory of Biomolecular Magnetic Resonance (LRMB), two subjects that are closely related to each other are presented in this article. On the one hand, we show how to populate long-lived states (LLS) that have long lifetimes T(LLS) which allow one to go beyond the usual limits imposed by the longitudinal relaxation time T1. This makes it possible to extend NMR experiments to longer time-scales. As an application, we demonstrate the extension of the timescale of diffusion measurements by NMR spectroscopy. On the other hand, we review our work on long-lived coherences (LLC), a particular type of coherence between two spin states that oscillates with the frequency of the scalar coupling constant J(IS) and decays with a time constant T(LLC). Again, this time constant T(LLC) can be much longer than the transverse relaxation time T2. By extending the coherence lifetimes, we can narrow the linewidths to an unprecedented extent. J-couplings and residual dipolar couplings (RDCs) in weakly-oriented phases can be measured with the highest precision.