Publications by authors named "Lena Kaufmann"

Since Jane Goodall's famous observations of stick tool use by chimpanzees, animal tool use has been observed in numerous species, including many primates, dolphins, and birds. Some animals, such as New Caledonian crows, even craft tools. Elephants frequently use tools and also modify them.

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Article Synopsis
  • The study examines the development of trunk wrinkles in Asian and African elephants, noting significant differences in wrinkle characteristics between the two species.
  • Asian elephants exhibit more pronounced dorsal trunk wrinkles compared to African elephants, with distinct density patterns based on anatomical location and trunk usage.
  • The research also highlights that trunk wrinkle formation is influenced by factors such as behavior, environment, and trunk lateralization, with specific growth patterns occurring during fetal development.
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Behavior and innervation suggest a high tactile sensitivity of elephant trunks. To clarify the tactile trunk periphery we studied whiskers with the following findings. Whisker density is high at the trunk tip and African savanna elephants have more trunk tip whiskers than Asian elephants.

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The cellular mechanisms of emotional contagion are unknown. We investigated tickle contagion and the underlying neuronal representations in playful rats. We recorded trunk somatosensory cortex activity of observer rats while they received tickling and audiovisual playback of tickling footage and while they witnessed tickling of demonstrator rats.

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We studied facial motor control in elephants, animals with muscular dexterous trunks. Facial nucleus neurons (~54,000 in Asian elephants, ~63,000 in African elephants) outnumbered those of other land-living mammals. The large-eared African elephants had more medial facial subnucleus neurons than Asian elephants, reflecting a numerically more extensive ear-motor control.

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The COVID-19 pandemic led to an abrupt change from in-person to online teaching in higher education, resulting in increased use of information and communication technology (ICT) and students' stress and uncertainty. Integrating theories of human motivation, stress, and humane work design, we investigated whether different types of action regulation hindrances (ARH) pertaining to human (ICT competence deficits), technology (technical problems), interaction (coordination difficulties), and task aspects (work overload) related to technostress (H1). Furthermore, we examined if this relationship was mediated by satisfaction of the basic human needs for competence, autonomy, and relatedness (H2).

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Sensory nerves are information bottlenecks giving rise to distinct sensory worlds across animal species. Here, we investigate trigeminal ganglion and sensory nerves of elephants. The elephant trigeminal ganglion is very large.

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The relationship between tickling, sensation, and laughter is complex. Tickling or its mere anticipation makes us laugh, but not when we self-tickle. We previously showed rat somatosensory cortex drives tickling-evoked vocalizations and now investigated self-tickle suppression and tickle anticipation.

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Both noncovalent and covalent encapsulations of active biomolecules, for example, proteins and oligonucleotides, for a new biosensor matrix in an in situ bioorthogonal hydrogel formation via a strain-promoted azide-alkyne cycloaddition reaction were investigated. Unspecific interaction between the gel and the biomolecules as well as protein denaturation was prevented by the bioorthogonal gel components, which ensure a uniform aqueous environment in the hydrogel network. No leaching of the active biomolecules was observed.

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We present two approaches to low-molecular-weight supramolecular gels bearing hydrophobic cavities based on calixarene-containing building blocks. Gels are formed by a calixarene based tetrahydrazide gelator or a co-gel of a calixarene diammonium salt and a bis-crown ether. The calixarene hydrophobic cavity enables the complexation of hydrophobic drug molecules in a generic fashion thus providing an anchor site on the surface of the gel fibre to initiate drug crystal nucleation and growth.

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The binding behaviour of differently substituted diamide axle molecules to Hunter/Vögtle tetralactam macrocycles was studied with a combination of NMR titration, isothermal titration calorimetry (ITC) experiments and calculations employing density functional theory (DFT), along with dispersion-corrected exchange-correlation functionals. Guests with alkyl or alkenyl chains attached to the diamide carbonyl groups have a significantly higher binding affinity to the macrocycle than guests with benzoyl amides and their substituted analogues. While the binding of the benzoyl and alkenyl substituted axles is enthalpically driven, the alkyl-substituted guest binds mainly because of a positive binding entropy.

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The non-covalent interactions of different upper-rim-substituted C(2)-resorcinarenes with tetramethylammonium salts were analyzed in the gas phase in an Electrospray Ionization Fourier-transform ion-cyclotron-resonance (ESI-FTICR) mass spectrometer and by (1)H NMR titrations. The order of binding strengths of the hosts towards the tetramethylammonium cation in the gas phase reflects the electronic nature of the substituents on the upper rim of the resorcinarene. In solution, however, a different trend with particularly high binding constants for halogenated resorcinarenes has been observed.

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A series of di-, tri- and tetravalent axles and wheels for the synthesis of pseudorotaxanes bearing the tetralactam macrocycle/diamide axle binding motif was prepared. Starting from iodinated monovalent precursors, Sonogashira cross-coupling reactions were utilized to couple the binding sites to appropriate spacer groups. Through this "Lego" or "toolbox" approach, the convergent synthesis of host and guests with a well-defined number of the binding sites is possible.

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Two amide [2]rotaxanes were synthesized in high yields using a novel N,N'-dipropargyl diketopiperazine axle centerpiece as the template to which the stoppers are attached through "click chemistry". (1)H and 2D NMR spectra provide evidence for two different H-bonding motifs, in one of which the triazole CH groups form C-H···O═C bonds with the wheel carbonyl O atoms. This motif can be controlled and switched reversibly by competitive anion binding.

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Tetralactam macrocycles can be functionalized by a variety of cross-coupling reactions. A modular "toolbox" strategy is presented that allows 1) several tetralactam macrocycles to be covalently connected with each other or with a central spacer, 2) the macrocycles to be substituted with or connected to different chromophores, and 3) metal-coordination sites to be attached to the macrocycles. With this approach a series of different oligo-macrocyclic hosts was obtained with great structural diversity and enormous potential for further functionalization.

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