Search results for "force"
showing 10 items of 3423 documents
Energy-related optimal control accounts for gravitational load: comparing shoulder, elbow, and wrist rotations.
2013
International audience; Gaveau J, Berret B, Demougeot L, Fadiga L, Pozzo T, Papaxanthis C. Energy-related optimal control accounts for gravitational load: comparing shoulder, elbow, and wrist rotations. J Neurophysiol 111: 4-16, 2014. First published October 16, 2013; doi: 10.1152/jn.01029.2012.-We permanently deal with gravity force. Experimental evidences revealed that moving against gravity strongly differs from moving along the gravity vector. This directional asymmetry has been attributed to an optimal planning process that optimizes gravity force effects to minimize energy. Yet, only few studies have considered the case of vertical movements in the context of optimal control. What kin…
Contactless magnetic excitation of acoustic cavitation in liquid metals
2015
A steady axial magnetic field is applied to a liquid metal zone heated by induction currents. The resulting alternating Lorentz force causes pressure oscillations that being strong enough lead to cavitation in the molten metal. Amplitude of the pressure oscillations is proportional to the product of the induced currents and the steady axial magnetic field induction. We follow an approach where the acoustic pressure is maximized by the induction currents. The onset of cavitation is identified by the occurrence of sub-harmonics of the drive frequency in sound recorded at the surface of the experimental cell. It is demonstrated that cavitation in a liquid metal may be excited by a superimposed…
Three-dimensional solvation structure of ethanol on carbonate minerals
2020
Calcite and magnesite are important mineral constituents of the earth’s crust. In aqueous environments, these carbonates typically expose their most stable cleavage plane, the (10.4) surface. It is known that these surfaces interact with a large variety of organic molecules, which can result in surface restructuring. This process is decisive for the formation of biominerals. With the development of 3D atomic force microscopy (AFM) it is now possible to image solid–liquid interfaces with unprecedented molecular resolution. However, the majority of 3D AFM studies have been focused on the arrangement of water at carbonate surfaces. Here, we present an analysis of the assembly of ethanol – an o…
Modal Analysis of a Reinforced Concrete Frame in Various States of Damage
2005
The purpose of this paper is to report selected results of an experiment in which two, natural size r/c frames were put on shaking table and subjected to a sequence of seismic excitations with increasing intensity interlaced with low level, diagnostic tests. The shaking table experiment aimed at working out new methodology for monitoring vibrations of r/c structures to assess their state. Characteristic decrease of natural frequencies and increase of structural damping was observed and analyzed in detail. It was interesting to note 20 per cent drop in natural frequencies prior to visual detection of any cracks.
Limit on the production of a light vector gauge boson in $\phi $ mesondecays with the KLOE detector
2012
We present a new limit on the production of a light dark-force mediator with the KLOE detector at DAPHNE. This boson, called U, has been searched for in the decay phi --> eta U, U --> e+ e-, analyzing the decay eta --> pi0 pi0 pi0 in a data sample of 1.7 fb-1. No structures are observed in the e+e- invariant mass distribution over the background. This search is combined with a previous result obtained from the decay eta --> pi+ pi- pi0, increasing the sensitivity. We set an upper limit at 90% C.L. on the ratio between the U boson coupling constant and the fine structure constant of alpha'/alpha < 1.7x10^-5 for 30<M_U<400 MeV and alpha'/alpha < 8x10^-6 for the sub-region 50<M_U<210 MeV. This…
Criminal networks analysis in missing data scenarios through graph distances.
2021
Data collected in criminal investigations may suffer from: (i) incompleteness, due to the covert nature of criminal organisations; (ii) incorrectness, caused by either unintentional data collection errors and intentional deception by criminals; (iii) inconsistency, when the same information is collected into law enforcement databases multiple times, or in different formats. In this paper we analyse nine real criminal networks of different nature (i.e., Mafia networks, criminal street gangs and terrorist organizations) in order to quantify the impact of incomplete data and to determine which network type is most affected by it. The networks are firstly pruned following two specific methods: …
Unprecedented intramolecular pancake bonding in a {Dy2} single-molecule magnet
2020
The first example of unique coordination induced intramolecular pancake bonding was achieved through the reduction of two bis(pyrazolyl)-tetrazine ligands, affording [MIII2(μ-(bpytz)2)(THMD)4](M = Dy, Y; bpytz = 3,6-bis(3,5-dimethyl-pyrazolyl)-1,2,4,5-tetrazine; TMHD = 2,2,6,6-tetramethyl-3,5-heptanedionate). To provide a cohesive magneto-structural correlation, the mono bis(pyrazolyl)-tetrazine bridged congener [DyIII2(μ-bpytz)(THMD)6]·4(C6H6) was also isolated. Both metal complexes exhibit single-molecule magnet behaviour under an applied dc field.
Enhanced β-turn conformational stability of tripeptides containing Δphe in cis over trans configuration
2013
Conformations of three pairs of dehydropeptides with the opposite configuration of the Delta Phe residue, Boc-Gly-Delta(Z/E)Phe-Phe-p-NA (Z- p -NA and E- p -NA), Boc-Gly-Delta(Z/E)Phe-Phe-OMe (Z-OMe and E-OMe), and Boc-Gly-Delta(Z/E)Phe-Phe-OH (Z-OH and E-OH) were compared on the basis of CD and NMR studies in MeOH, TFE, and DMSO. The CD results were used as the additional input data for the NMR-based calculations of the detailed solution conformations of the peptides. It was found that Z- p -NA, E- p -NA, Z-OMe, and Z-OH adopt the beta-turn conformations and E-OMe and E-OH are unordered. There are two overlapping type III beta-turns in Z- p -NA, type II' beta-turn in E- p -NA, and type II …
Influence of solvents on conformation of dehydropeptides
2013
Abstract Structural investigations of dehydropeptides containing (Z)-dehydrophenylalanine in solvents characterized by different polarity are discussed. The conformational analysis are based on spectroscopic methods (NMR, CD), molecular modeling techniques and in case of the tripeptide, ab initio methods. The results of temperature experiment indicate, that the only conformation of the investigated hexapeptide 3 is stabilized by intramolecular hydrogen bonds. Depending on the length of the peptide chain, the polarity of solvent influences on arrangement of the side chain of the amino acids or of the main chain of the peptide.
Conformational analysis of α,β-dehydropeptide models at the HF and DFT levels
2004
Abstract The Ramachandran potential energy surfaces of N-acetyl-α,β-dehydroamino acid N′-monomethylamides Ac-ΔXaa-NHMe (ΔXaa=ΔAla, (Z)-ΔPhe; 1, 2) and N-acetyl-α,β-dehydroamino acid N′,N′-dimethylamides Ac-ΔXaa-NMe2 (ΔXaa=ΔAla, (Z)-ΔPhe, (Z)-ΔAbu; 3–5) were calculated at the HF/6-31G*//HF/3-21G level. The conformers localised were fully optimised at the DFT/B3LYP/6-31+G** level and their relative stabilities were analysed in terms of both π-conjugation and internal hydrogen bonding. The Ac-ΔXaa-NMe2 molecules reveal the low-energy conformer H/F, φ=−41±4°, ψ=128±4°, which is not too easily accessible for common amino acid residues. This conformer is stabilised by the bifurcated N2–CH3 O1 int…