Articulated blade tip devices for load alleviation on wind turbines

This paper investigates the load alleviation capabilities of an articulated tip device, where the outermost portion of the blade can rotate with respect to the rest of the blade. Passive, semi-passive and active solutions are developed for the tip rotation. In the passive and semi-passive configurations tip pitching is mainly driven by aerodynamic loads, while for the active case the rotation is obtained with an actuator commanded by a feedback control law. Each configuration is analyzed and tested using a high-fidelity aeroservoelastic simulation environment, by considering standard operative conditions as well as fault situations. The potential benefits of the proposed blade tip concepts are discussed in terms of performance and robustness

Synchronized onset of nuclear and cell surface modifications in U937 cells during apoptosis

In this study we investigated the relationship between nuclear and cell surface modifications (i.e. blebbing, phosphatidylserine [PS] and sugar residues exposure) in a monocytic cell line, U937, during apoptosis induced by oxidative stress (1mM H2O2) or inhibition of protein synthesis (10 mg/ml puromycin). Dying cells were simultaneously observed for nuclear modifications, presence of superficial blebs and plasma membrane alterations. Morphological analysis performed by conventional fluorescence microscopy, or by transmission and scanning electron microscopy showed that the courses of nuclear and membrane alterations occured concomitantly, but the phenotype was dependent on the stage of the apoptotic process and the type of apoptogenic inducer used. The progression of apoptosis in U937 cells beyond early stages resulted in the extensive formation of blebs which concomitantly lost some typical markers of apoptosis, such as PS and sugar residues. Therefore, the modality by which the nucleus condenses, or the amount and the pattern of distribution of PS on the cell surface were, for each cell line, strictly related to the apoptogenic inducer. The morphological data reported in the present paper should lead to a more precise quantification of apoptosis by improving the detection of apoptotic cells in vivo (i.e. in tissue, organs), which is a crucial point in the evaluation of efficiency of antiproliferative drugs, such as antiblastic or immunosuppressive compounds

Do we become more cautious for others when large amounts of money are at stake?

A considerable proportion of financial decisions are made by agents acting on behalf of other people. Although people are more cautious for others when making medical decisions, this does not seem to be the case for economic decisions. However, studies with large amounts of money are particularly absent from the literature, which precludes a clear comparison to studies in the medical domain. To address this gap, we investigated the effect of outcome magnitude in two experiments where participants made choices between safe and risky options. Decision-makers were not more cautious for others over large amounts. In fact, risk-taking was accentuated for large amounts in the gain domain. We did not find self-other differences in the loss domain for either outcome magnitude. This suggests that the caution observed in medical decisions does not replicate in financial decisions with large amounts, or at least not in the same way. These results echo the concerns that have been raised about excessive risk-taking by financial agents

pH-Dependent structuring and fluorescence properties of tryptophan-derived polyamidoamino acids

The binding sites of proteins often contain tryptophan residues, whose fluorescent properties may be altered upon ligand binding. Conformational changes within the binding site can result in either fluorescence quenching or enhancement, which may be utilized to quantitatively investigate protein-ligand interactions. Amphoteric fluorescent (L)-, (D)- and (D,L)-tryptophan-deriving polyamidoamino acid (PAAC) homopolymers and their copolymers with glycine and arginine PAAC copolymers were synthesized by the polyaddition of N,N'-methylenebisacrylamide (MBA) with (L)-, (D)- and (D,L)-tryptophan and, respectively, glycine- and (L)-arginine/(L)-tryptophan mixtures. The polymerization reaction was run at 50\ub0C and pH>10 for 7 days under nitrogen atmosphere. All polymers were characterized by NMR spectrometry, UV-Visible spectroscopy, dynamic light scattering (DLS), steady state and time-resolved fluorescence (TRF) spectroscopy. Solubility in aqueous systems at different pH\u2019s was determined by measuring the transmittance at 450 nm. Homopolymers showed similar pH-dependent solubility patterns, with steep solubility drop at pH < 8. Volumetric particle size distribution obtained by DLS analysis showed hydrodynamic radii (Rh) 48 100 nm and negligible changes with pH. Fluorescence quantum yield of the MBA-L-tryptophan measured at 10-5 M repeating unit concentration decreased from 6 to 4 % from pH 11 to 8 respectively. Excitation and emission spectra showed maxima at 279 nm and 370 nm respectively, the latter showing a 20 nm blue shift by decreasing pH from 11 to 8. The excited-state lifetimes of the MBA-(L)-tryptophan at the maximum emission wavelength decreased from \u3c41 = 0.90 ns, \u3c42 = 4.40 ns to \u3c41 = 0.81 ns, \u3c42 = 3.49 ns passing from pH 11 to 8, with a population redistribution in favour of the shortest time. PAAC copolymers were synthesized under the same conditions of the homopolymers. The solubility curves in water of copolymers showed complete solubility for tryptophan content up to 20 % on a molar basis. For tryptophan content up to 30 and 40%, transmittance dropped down, respectively, to 60 % and 5 % in the pH range 2-7. DLS measurements at different pH\u2019s showed average volume particle size 2.5 nm in the range considered. Preliminary TRF spectroscopy data proved that PAAC copolymers were endowed with pH-dependent emission properties. Moreover, significant fluorescence quantum yield was detected at the tryptophan content as low as 5 %. Finally, preliminary circular dichroism measurements showed pH-dependent patterns. In conclusion, tryptophan-based PAAC polymers displayed tunable amphiphilicity, chirality and self-assembly properties

pH-Dependent structuring and fluorescence properties of tryptophan-derived polyamidoamino acids

The binding sites of proteins often contain tryptophan residues, whose fluorescent properties may be altered upon ligand binding. Conformational changes within the binding site can result in either fluorescence quenching or enhancement, which may be utilized to quantitatively investigate protein-ligand interactions. Amphoteric fluorescent (L)-, (D)- and (D,L)-tryptophan-deriving polyamidoamino acid (PAAC) homopolymers and their copolymers with glycine and arginine PAAC copolymers were synthesized by the polyaddition of N,N'-methylenebisacrylamide (MBA) with (L)-, (D)- and (D,L)-tryptophan and, respectively, glycine- and (L)-arginine/(L)-tryptophan mixtures. The polymerization reaction was run at 50\ub0C and pH>10 for 7 days under nitrogen atmosphere. All polymers were characterized by NMR spectrometry, UV-Visible spectroscopy, dynamic light scattering (DLS), steady state and time-resolved fluorescence (TRF) spectroscopy. Solubility in aqueous systems at different pH\u2019s was determined by measuring the transmittance at 450 nm. Homopolymers showed similar pH-dependent solubility patterns, with steep solubility drop at pH < 8. Volumetric particle size distribution obtained by DLS analysis showed hydrodynamic radii (Rh) 48 100 nm and negligible changes with pH. Fluorescence quantum yield of the MBA-L-tryptophan measured at 10-5 M repeating unit concentration decreased from 6 to 4 % from pH 11 to 8 respectively. Excitation and emission spectra showed maxima at 279 nm and 370 nm respectively, the latter showing a 20 nm blue shift by decreasing pH from 11 to 8. The excited-state lifetimes of the MBA-(L)-tryptophan at the maximum emission wavelength decreased from \u3c41 = 0.90 ns, \u3c42 = 4.40 ns to \u3c41 = 0.81 ns, \u3c42 = 3.49 ns passing from pH 11 to 8, with a population redistribution in favour of the shortest time. PAAC copolymers were synthesized under the same conditions of the homopolymers. The solubility curves in water of copolymers showed complete solubility for tryptophan content up to 20 % on a molar basis. For tryptophan content up to 30 and 40%, transmittance dropped down, respectively, to 60 % and 5 % in the pH range 2-7. DLS measurements at different pH\u2019s showed average volume particle size 2.5 nm in the range considered. Preliminary TRF spectroscopy data proved that PAAC copolymers were endowed with pH-dependent emission properties. Moreover, significant fluorescence quantum yield was detected at the tryptophan content as low as 5 %. Finally, preliminary circular dichroism measurements showed pH-dependent patterns. In conclusion, tryptophan-based PAAC polymers displayed tunable amphiphilicity, chirality and self-assembly properties

Am I My Peer's Keeper? Social Responsibility in Financial Decision Making

Decision makers often take risky decisions on the behalf of others rather than for themselves. Competing theoretical models predict both, higher as well as lower levels of risk aversion when taking risk for others, and the experimental evidence is mixed. In our within-subject design, money managers have substantial responsibility by taking investment decisions for themselves and for a group of six clients, when payments are either fixed or perfectly aligned. We find that money managers invest significantly less for others than for themselves (cautious shift) which is mainly driven by a less risk averse sub sample. Digging deeper we find money managers to rather act in line with what they believe the clients would invest for themselves. We derive a responsibility weighting function to show that with a perfectly aligned payment the money manager weights egoistic and social preferences. Finally we bring our results in perspective with the mixed experimental literature.Ein großer Teil risikoreicher, ökonomischer Entscheidungen wird von Dritten anstelle der Betroffenen getroffen. In solchen Fällen sagt die eine Klasse theoretischer Modelle geringere Risikoaversion voraus, eine andere Klasse aber höhere Risikoaversion im Vergleich zur Situation, bei der der Betroffene selbst die Entscheidung trifft. Die bisherigen empirischen Ergebnisse aus Laborexperimenten sind ebenso gemischt oder finden keine Unterschiede zwischen der Entscheidung für sich selbst oder für andere Personen. Wir verwenden ein 'within-subjects' für unser Experiment, bei dem Vermögensverwalter in unterschiedlichen Stufen für sich selbst, für eine Gruppe von Klienten, oder für sich selbst und eine Gruppe von Klienten Investitionsentscheidungen treffen. Wir erhöhen dabei die Soziale Verantwortung über die Größe der Gruppe von Investoren, um Verantwortungseffekte zu verstärken. Unsere Ergebnisse zeigen, dass das Risiko bei der Investition für andere signifikant geringer ist als bei der Investition für sich selbst. Dieses Aggregat-Ergebnis ist allerdings nur durch eine unterdurchschnittlich risikoaverse Subpopulation unserer Stichprobe getrieben. Eine genauere Analyse der Investitionsmotive zeigt, dass die Vermögensverwalter gemäß ihrer Erwartung der Klienten-Präferenzen handeln. Wir passen eine Nutzenfunktion mit Verantwortungs-Gewichten an und finden, dass die beobachtete Riskioaversion bei gemeinschaftlichen Investitionen durch egoistische und soziale Präferenzen erklärt werden kann. Abschließend stellen wir unsere Ergebnisse in den Kontext der bisherigen Literatur und versuchen die gemischten, bisherigen Ergebnisse aufgrund unserer Erkenntnisse zu erklären