The active control of wing rotation by Drosophila

This paper investigates the temporal control of a fast wing rotation in flies, the ventral flip, which occurs during the transition from downstroke to upstroke. Tethered flying Drosophila actively modulate the timing of these rapid supinations during yaw responses evoked by an oscillating visual stimulus. The time difference between the two wings is controlled such that the wing on the outside of a fictive turn rotates in advance of its contralateral partner. This modulation of ventral-flip timing between the two wings is strongly coupled with changes in wing-stroke amplitude. Typically, an increase in the stroke amplitude of one wing is correlated with an advance in the timing of the ventral flip of the same wing. However, flies do display a limited ability to control these two behaviors independently, as shown by flight records in which the correlation between ventral-flip timing and stroke amplitude transiently reverses. The control of ventral-flip timing may be part of an unsteady aerodynamic mechanism that enables the fly to alter the magnitude and direction of flight forces during turning maneuvers

A sub-Doppler resolution double resonance molecular beam infrared spectrometer operating at chemically relevant energies (~2 eV)

A molecular beam spectrometer capable of achieving sub-Doppler resolution at 2 eV (~18 000 cm^–1) of vibrational excitation is described and its performance demonstrated using the CH stretch chromophore of HCN. Two high finesse resonant power-buildup cavities are used to excite the molecules using a sequential double resonance technique. A v = 0-->2 transition is first saturated using a 1.5 µm color center laser, whereupon a fraction of the molecules is further excited to the v = 6 level using an amplitude modulated Ti:Al2O3 laser. The energy absorbed by the molecules is detected downstream of both excitation points by a cryogenically cooled bolometer using phase sensitive detection. A resolution of approximately 15 MHz (i.e., three parts in 10^8) is demonstrated by recording a rotational line in the v = 6 manifold of HCN. Scan speeds of up to several cm^–1/h were obtained, with signal-to-noise ratios in excess of 100. The high signal-to-noise ratio and a dynamic range of 6×10^4 means that future experiments to study statistical intramolecular vibrational energy redistribution in small molecules and unimolecular isomerizations can be attempted. We would also like to point out that, with improved metrology in laser wavelengths, this instrument can also be used to provide improved secondary frequency standards based upon the rovibrational spectra of molecules

Preparation, Structure, and Reactivity of Nonstabilized Organoiron Compounds. Implications for Iron-Catalyzed Cross Coupling Reactions

A series of unprecedented organoiron complexes of the formal oxidation states −2, 0, +1, +2, and +3 is presented, which are largely devoid of stabilizing ligands and, in part, also electronically unsaturated (14-, 16-, 17- and 18-electron counts). Specifically, it is shown that nucleophiles unable to undergo β-hydride elimination, such as MeLi, PhLi, or PhMgBr, rapidly reduce Fe(3+) to Fe(2+) and then exhaustively alkylate the metal center. The resulting homoleptic organoferrate complexes [(Me4Fe)(MeLi)][Li(OEt2)]2 (3) and [Ph4Fe][Li(Et2O)2][Li(1,4-dioxane)] (5) could be characterized by X-ray crystal structure analysis. However, these exceptionally sensitive compounds turned out to be only moderately nucleophilic, transferring their organic ligands to activated electrophiles only, while being unable to alkylate (hetero)aryl halides unless they are very electron deficient. In striking contrast, Grignard reagents bearing alkyl residues amenable to β-hydride elimination reduce FeXn (n = 2, 3) to clusters of the formal composition [Fe(MgX)2]n. The behavior of these intermetallic species can be emulated by structurally well-defined lithium ferrate complexes of the type [Fe(C2H4)4][Li(tmeda)]2 (8), [Fe(cod)2][Li(dme)]2 (9), [CpFe(C2H4)2][Li(tmeda)] (7), [CpFe(cod)][Li(dme)] (11), or [Cp*Fe(C2H4)2][Li(tmeda)] (14). Such electron-rich complexes, which are distinguished by short intermetallic Fe−Li bonds, were shown to react with aryl chlorides and allyl halides; the structures and reactivity patterns of the resulting organoiron compounds provide first insights into the elementary steps of low valent iron-catalyzed cross coupling reactions of aryl, alkyl, allyl, benzyl, and propargyl halides with organomagnesium reagents. However, the acquired data suggest that such C−C bond formations can occur, a priori, along different catalytic cycles shuttling between metal centers of the formal oxidation states Fe(+1)/Fe(+3), Fe(0)/Fe(+2), and Fe(−2)/Fe(0). Since these different manifolds are likely interconnected, an unambiguous decision as to which redox cycle dominates in solution remains difficult, even though iron complexes of the lowest accessible formal oxidation states promote the reactions most effectively

Social robots in educational contexts: developing an application in enactive didactics

Due to advancements in sensor and actuator technology robots are becoming more and more common in everyday life. Many of the areas in which they are introduced demand close physical and social contact. In the last ten years the use of robots has also increasingly spread to the field of didactics, starting with their use as tools in STEM education. With the advancement of social robotics, the use of robots in didactics has been extended also to tutoring situations in which these \u201csocially aware\u201d robots interact with mainly children in, for example, language learning classes. In this paper we will give a brief overview of how robots have been used in this kind of settings until now. As a result it will become transparent that the majority of applications are not grounded in didactic theory. Recognizing this shortcoming, we propose a theory driven approach to the use of educational robots, centred on the idea that the combination of enactive didactics and social robotics holds great promises for a variety of tutoring activities in educational contexts. After defining our \u201cEnactive Robot Assisted Didactics\u201d approach, we will give an outlook on how the use of humanoid robots can advance it. On this basis, at the end of the paper, we will describe a concrete, currently on-going implementation of this approach, which we are realizing with the use of Softbank Robotics\u2019 Pepper robot during university lectures

Photometric and spectroscopic variability of 53 Per

A new investigation of the variability of the SPB-type star 53 Per is presented. The analysis of the BRITE photometry allowed us to determine eight independent frequencies and the combination one. Five of these frequencies and the combination one were not known before. In addition, we gathered more than 1800 new moderate and high-resolution spectra of 53 Per spread over approximately six months. Their frequency analysis revealed four independent frequencies and the combination one, all consistent with the BRITE results.Comment: 2 pages, accepted for publication in the Proceedings of the PAS (Proc. of the 2nd BRITE Science conference, Innsbruck

The non-destructive study of museums objects by means of neutrons imaging methods and results of investigations

Based on experience from many kinds of investigations with neutron imaging methods (radiography, tomography, time-dependent studies) and in comparison to conventional X-ray methods, the authors discuss the potential of future improved studies for cultural-heritage purposes. Whereas the focus of the paper is on the imaging aspect, other established techniques as neutron activation analysis (NAA), prompt gamma activation analysis (PGAA), neutron-induced autoradiography and neutron scattering are mentioned too. Although a great potential for studies similar to those described in the paper exists, a considerable effort is needed to define the best-suited methods for the dedicated cultural historical request. A real barrier between the experts at large research facilities (as, e.g., neutron sources are) and the partners from the museums side has to be overcome in order to solve the problems. A joint European approach will help in this respect

Neutron radiography, tomography, and diffraction of commercial lithium-ion polymer batteries

Imaging an intact, commercial battery as it cycles and wears is proved possible with neutron imaging. The wavelength range of imaging neutrons corresponds nicely with crystallographic dimensions of the electrochemically active species and the metal electrodes are relatively transparent. The time scale of charge/discharge cycling is well matched to dynamic tomography as performed with a golden ratio based projection angle ordering. The hydrogen content does create scatter which tends to blur internal structure. In this report, three neutron experiments will be described: 3D images of charged and discharged batteries were obtained with monochromatic neutrons at the FRM II reactor. 2D images (PSI) of fresh and worn batteries as a function of charge state may show a new wear pattern. In situ neutron diffraction (SNS) of the intact battery provides more information about the concentrations of electrochemical species within the battery as a function of charge state and wear. The combination of 2D imaging, 3D imaging, and diffraction data show how neutron imaging can contribute to battery development and wear monitoring. © 2013 The Authors. © 2013 The Authors