796 research outputs found
Studying Form, Color, and Pictorial Composition in the New England Landscape
When I applied for a grant through the Research and Apprenticeship Program (REAP) at the University of New Hampshire (UNH) during the spring of 2016, my intention was to gain more experience in the art of painting outdoors. By looking through the student work of my favorite painters I realized that most of them had spent some concentrated period of time studying landscape painting and producing dozens or even hundreds of small sketches of different scenes and times of day outdoors. I knew that if I was going to advance toward my own artistic goals, I needed to apply myself to those studies as well. First, I wanted to study different effects of light outdoors and learn more about color relations through the constant practice of observation and color mixing. Second, I wanted to learn more about how to express complex forms in a broad and simplified way, an underlying principle of theway nearly all great painters see the world. Third, I wanted to learn more about composing pictures by persistently producing small studies (usually between 8 x 10 inches and 12 x 16 inches) and thinking about the principles of good composition for each one. The complexity of landscape as a subject made it a great source of practice for all three of my goals.The best thing I gained from the summer’s work was actually something I lost. I lost the crippling timidity that often kept me from painting outside.I can deal with the fear of failure that stares back at you when you look at a blank canvas. I can deal with people laughing at my silly painting outfit or coming up and asking questions, with the wind blowing a wet canvas off my easel and into my clothing, with standing in the sun for hours on a hot day wearing long pants and a long-sleeved shirt to shield my Irish skin. All that is part of the fun of landscape painting, and none of it distracts me much anymore. That’s good, because a landscape painter has too much else to think about
The use of survey weights in regression analysis
While there is a wide consensus in using survey weights when estimating population parameters, it is not clear what to do when using survey data for analytic purposes (i.e. with the objective of making inference about model parameters). In the model-based framework (MB), under the hypothesis that the underlying model is correctly specified, using survey weights in regression analysis potentially involves a loss of efficiency. In a design-based perspective (DB), weighted estimates are both design consistent and can provide robustness to model mis-specification. In this paper, I suggest that the choice of using survey weights can be seen in a regression diagnostic set. The survey data analyst should check if the design information included in survey weights has some explanatory power in describing the model outcome. To accomplish this task a set of econometric tests is suggested, that could be supplemented by the analysis of model features under the two strategies.survey methods, model evaluation and testing
The demand for energy of Italian households
This paper studies the impact of demographic shifts, energy prices and climate factors on Italian households’ energy budget. The pattern of energy expenditure of Italian households is studied using the Italian Household Budget Survey. The expenditure for heating, private transport and electricity are jointly modelled and the relevant parameters are simulated under different scenarios. According to this exercise, the ageing of the Italian population - coupled with the increase in energy prices and surface temperature - could reduce the share of energy-related expenditure by about 2 percentage points in the next few decades and increase its polarization. Energy policies should take into consideration households’ characteristics and behaviour, and in turn the impact of this heterogeneity on the demand for energy.household energy demand, demographics, climate change
Accounting for sampling design in the SHIW
This paper analyses how sampling design affects variance estimates and inference using the data collected by the Survey on Household Income and Wealth (SHIW). The SHIW combines three basic features: stratification, clustering, and weighting to correct for unequal probabilities of selection among sampling units. A model to assess variance is presented and a Jackknife Repeated Replication method is suggested to estimate variance. Empirical evidence shows that: 1) simple random sampling formula for variance underestimates by a factor of between 3 and 2 the estimates that take into account all the design features; 2) the bias of unweighted estimates may be fairly substantial; 3) all these factors can seriously mislead inference based on SHIW data.Survey Methods
The Weighting Process in the SHIW
The design of a probability sample jointly determines the method used to select sampling units from the population and the estimator of the population parameter. If the sampling fraction is constant for all the units in the sample, then the unweighted sampling mean is an unbiased estimator. In the Survey on Household Income and Wealth (SHIW), units included in the sample have unequal probabilities of selection and each observation is weighted using the inverse of the proper sampling fraction (design weight) adjusted for the response mechanism (nonresponse weight) and for other factors such as imperfect coverage. In this paper we present the weighting scheme of the SHIW and assess its impact on bias and variance of selected estimators. Empirical evidences show that the increasing variability induced by using weighted estimators is compensated by the bias reduction even when performing analysis on sample domains. A set of longitudinal weights is also proposed to account for the selection process and the attrition of the SHIW panel component. These weights, giving their enhanced description of the “panel population”, should be better suited to perform longitudinal analysis; nevertheless their higher variance implies that they wouldn’t always be preferable in terms of mean square error.Survey Methods
"Household Wealth Distribution in Italy in the 1990s"
This paper describes the composition and distribution of household wealth in Italy. First, the evolution of household portfolios over the last 40 years is described on the basis of newly reconstructed aggregate balance sheets. Second, the characteristics and quality of the main statistical source on wealth distribution, the Bank of Italy’s Survey of Household Income and Wealth, are examined together with the statistical procedures used to adjust for nonresponse, nonreporting and underreporting. The distribution of household net worth is then studied using both adjusted and unadjusted data. Wealth inequality is found to have risen steadily during the 1990s. The increased concentration of financial wealth was an important factor in determining this path.
Household Wealth Distribution in Italy in the 1990s
This paper describes the composition and distribution of household wealth in Italy. First, the evolution of household portfolios over the last forty years is described on the basis of newly reconstructed aggregate balance sheets. Second, the characteristics and quality of the main statistical source on wealth distribution, the Bank of ItalyÂ’s Survey of Household Income and Wealth, are examined together with the statistical procedures used to adjust for non-response, non-reporting and under-reporting. The distribution of household net worth is then studied using both adjusted and unadjusted data. Wealth inequality is found to have risen steadily during the 1990s. The increased concentration of financial wealth was an important factor in determining this path.household wealth, wealth inequality, Italy
Metalloprotein models: developing catalytic systems
Metal–containing proteins are of particular interest: they are responsible for catalysing important biological process, such as photosynthesis, respiration, water oxidation, molecular oxygen reduction and nitrogen fixation. Understanding the structure-function relationship in protein science is an outstanding issue to disclose how macromolecules work, with the ultimate goal to reproduce or modify their activity and to design new enzymes for tailored applications.To this end, metalloprotein mimetics have been developed through the introduction of novel metal-binding sites into naturally occurring proteins as well as through de novo protein design. In this thesis, the challenge of reproducing metalloprotein active sites was approached by using a miniaturization process. The attention was centered on natural iron-containing proteins and on artificial models called DFs and Mimochromes, which encompass the structural and functional features of di-iron-oxo proteins and heme-proteins, respectively. Both classes of miniaturized models demonstrate the importance of considering numerous structural issues in protein design, to obtain soluble and stable molecules, and to optimize metal-binding sites for function.
This thesis reports the functional and chemico-physical properties of DF3, a de novo designed di-iron protein model. DF3 is the latest member of the DF family of synthetic proteins. They consist of helix–loop–helix hairpins, designed to dimerize and form an antiparallel four-helix bundle that encompasses a metal-binding site similar to those of non-heme carboxylate-bridged di-iron proteins. All the spectroscopic and structural features reported herein demonstrate the ability of a designed protein to finely tune the active-site structure to accommodate different metal ions and exogenous ligands. Further, the complete analysis of the di-iron complex supports the ability of di-Fe(III)–DF3 to catalyze oxidation reactions, in particular of phenols to quinines. To confirm the structural basis for DF3 catalytic activity, its NMR solution structure was solved using the diamagnetic di-Zn(II) derivative.
Then, structural features of DFs and natural di-iron proteins, as well as functional elements of Mimochromes and natural horseradish peroxidase, were borrowed to obtain a de novo protein class with five-coordinated heme-complex and peroxidase activity, named MPs (Mini-Peroxidases). The basic structure of these models consists in a deuterohemin covalently linked to two helix-loop-helix peptide chains. The active site presents (i) an homo-Cys/His residue in a single chain that acts as axial ligand to the iron ion, leaving the sixth coordination site able to accommodate exogenous ligands or substrates; (ii) an Arg residue in the distal site that should be able to activate hydrogen peroxide to give HRP-like catalytic process. The last analogue MP3 was partially characterized as the iron ion species, and its biocatalytic efficiency respect to natural systems was evaluated.
In summary, this thesis reports the last achievements in protein design of di-iron-oxo-proteins with desired catalytic activity; it also reports design, synthesis and characterization of a new class of peptide-based heme-models, named MPs, as well as preliminary catalytic activity studies
Agriculture damage data collection: A model for reconstructing comprehensive damage dynamics
The number of disasters, and particularly the number of weather-related events, which strongly threaten the Agriculture Sector given the sector's crucial dependence on climate, has increased significantly over the last decades. In such a context, accurate sector- specific disaster losses and damage data are a crucial indication for policy-making and for evaluating progress in reducing disaster risk. A better understanding of the mechanisms impacting the Agriculture Sector is needed. This paper responds to the necessity of improved damage and loss data collection for the Agriculture sector proposing a comprehensive conceptual model supporting damage assessment. On the one hand, the proposed conceptual model has been designed with the aim to be compliant to the Sendai Framework requirements while enforcing the assessment of damages in agriculture with a multi-temporal dimension. Considering a multi-step assessment of damages is one of the main results that are implemented in the model. On the other hand, Agriculture damage data stored in the proposed relational database would allow tracking the damage evolution enabling the damage dynamics reconstruction. Another key factor resides in the conception behind the database which begins from the theory – international policies and guidelines– till the practice – adopted damage assessment forms–, this exploratory approach allowed to create a model that represents not only the immediate, direct, physical impact of an event, but also the indirect and systemic consequences related to the inter- and intra-dependencies of the different elements constituting the Agriculture sector
Isolation and structural characterization of diterpenoidic compounds and identification of their molecular targets
As part of an ongoing research program on plants biosynthesizing diterpenes, it was performed a project aimed to create a diterpenes library from different plant’s species. The attention was paid on plants known to be rich on diterpenes, since they are a class of natural terpenoids with a great structural variability and a wide spectrum of biological activities.
Podocarpus elongatus (Aiton) L’Hèr. ex Pers, Podocarpus gracilior Pilger (Podocarpaceae), Clerodendrum splendens G. Don. (Verbenaceae), and Sideritis pullulans Vent. (Lamiaceae) were selected.
The new diterpenes nagilactone C 7-O-alpha-L-arabinopyranosyl-(1-4)-beta-D-xylopyranoside, nagilactone C 7-O-beta-D-glucopyranosyl-(1-4)-beta-D-xylopyranoside, nagilactone C 7-O-beta-D-xylopyranoside, nagilactone A 7-O-alpha-L-arabinopyranosyl-(1-4)-beta-D-xylopyranoside, 2beta,15S,16,17,19-pentahydroxy-isopimar-8(14)-ene 17-O-beta-D-glucopyranoside, 2beta,15R,16,17,19-pentahydroxy-isopimar-8(14)-ene 17-O-beta-D-glucopyranoside, and the known diterpenes 4-carboxy-19-nor-totarol, nagilactone B, and nagilactone C were isolated from P. elongatus leaves.
The new diterpenes 2alpha,16-dihydroxy-4beta-carboxy-O-beta-D-glucopyranosyl-19-nor-totarol, nagilactone K together with the known nagilactone B, nagilactone C, nagilactone D, and podolactone B were isolated from P. gracilior leaves.
The new diterpenoidic compounds 2alpha-acetoxy-3beta-(2’,3’-diacetoxy-2’-methyl)-butanoyloxy-14-hydro-15-hydroxyclerodin, 3,15-dihydroxy-14-hydro-clerodin, 2alpha,15-dihydroxy-3beta-(2’-hydroxy-3’-acetoxy-2’-methyl)-butanoyloxy-6alpha,18-diacetoxy-4alpha,17-epoxy-clerodan-11,16-lactone, 3beta,14S,15-trihydroxy-6alpha,18-diacetoxy-4alpha,17-epoxy-clerodan-11,16-lactone, and the only known 14,15-dihydroxy-3-epicarioptin were found in C. splendens leaves.
The new diterpenes, ent-1α,3α,7β,18-tetrahydroxykaur-16-ene, ent-3α,11α,18-trihydroxy-17-norkauran-16-ene, ent-3α,7β,18-trihydroxy-17-norkauran-16-one, ent-3α,7β-dihydroxy-18-acetyloxy-17-norkauran-16-one, ent-3α,7β,16α,17-tetrahydroxy-18-acetyloxy-kaurane, ent-7β,16α,17,18-tetrahydroxykaurane, and the known foliol, linearol, ent-3α,7β,17-trihydroxy-18-acetyloxy-15α,16α-epoxykaurane were isolated from S. pullulans leaves.
Finally, some diterpenes of our library were subjected to a chemical proteomics study as a strategy for the molecular target identification of natural bioactive compounds, setting up a method for the research of their molecular targets.
A fishing for partners study reveals Hsp70 and PPARγ as potential proteic target of 15-ketoatractyligenin methyl ester, a semi-synthetic ent-kaurane, while studies based on limited proteolysis-mass spectrometry strategy, free cell assays, and pro-apoptotic activity of hardwiickik acid in human monocytes allowed to validate Hsp27 as target for the clerodane diterpene
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