University of Jena

About: University of Jena is a education organization based out in Jena, Thüringen, Germany. It is known for research contribution in the topics: Laser & Population. The organization has 22198 authors who have published 45159 publications receiving 1401514 citations. The organization is also known as: Friedrich-Schiller-Universität Jena & Friedrich Schiller University Jena.

Basic limb kinematics of small therian mammals

Abstract: A comparative study of quantitative kinematic data of fore- and hindlimb movements of eight different mammalian species leads to the recognition of basic principles in the locomotion of small therians. The description of kinematics comprises fore- and hindlimb movements as well as sagittal spine movements including displacement patterns of limb segments, their contribution to step length, and joint movements. The comparison of the contributions of different segments to step length clearly shows the proximal parts (scapula, femur) to produce more than half of the propulsive movement of the whole limb at symmetrical gaits. Basically, a three-segmented limb with zigzag configuration of segments is mainly displaced at the scapular pivot or hip joint, both of which have the same vertical distance to the ground. Two segments operate in matched motion during retraction of the limb. While kinematic parameters of forelimbs are independent of speed and gait (with the scapula as the dominant element), fundamental changes occur in hindlimb kinematics with the change from symmetrical to in-phase gaits. Forward motion of the hindlimbs is now mainly due to sagittal lumbar spine movements contributing to half of the step length. Kinematics of small therian mammals are independent of their systematic position, their natural habitat, and also of specific anatomical dispositions (e.g. reduction of fingers, toes, or clavicle). In contrast, the possession of a tail influences 'pelvic movements'.

Magnetic properties of the znfe2o4 spinel

Abstract: Using neutron diffraction (ND), muon-spin rotation/relaxation ($\ensuremath{\mu}\mathrm{SR}$), and $^{57}\mathrm{Fe}$ and $^{67}\mathrm{Zn}$ M\"ossbauer spectroscopy (MS) we investigated magnetic properties of the normal spinel Zn${\mathrm{Fe}}_{2}$${\mathrm{O}}_{4}$. Inversion is below limits of detection in samples which were slowly cooled from 1200 \ifmmode^\circ\else\textdegree\fi{}C to room temperature. Below ${T}_{N}=10.5$ K the spinel exhibits long-range antiferromagnetic order (LRO). However, already at temperatures of about $T\ensuremath{\approx}10{T}_{N}$ a short-range antiferromagnetic order (SRO) develops which extends through \ensuremath{\approx}70% of the sample volume just above ${T}_{N}$. Below ${T}_{N}$ antiferromagnetic SRO and LRO coexist. At 4.2 K still \ensuremath{\approx}20% of the sample are short-range ordered. The regions exhibiting SRO are very small (\ensuremath{\approx}3 nm). Their fluctuation rates as estimated from $\ensuremath{\mu}\mathrm{SR}$ are in the GHz range. For this reason the SRO above ${T}_{N}$ remains hidden in MS and is only seen in ND and $\ensuremath{\mu}\mathrm{SR}$ with their more appropriate time windows. Although the physical origin of the SRO remains an enigma, our experiments show that it is not caused by partial inversion but rather is an intrinsic property of Zn${\mathrm{Fe}}_{2}$${\mathrm{O}}_{4}$. Modern ab initio cluster calculations successfully describe the magnetic hyperfine field as well as the electric field gradient tensor at the Fe site as seen by MS.

Observation of optical solitons in PT-symmetric lattices

Abstract: Controlling light transport in nonlinear active environments is a topic of considerable interest in the field of optics. In such complex arrangements, of particular importance is to devise strategies to subdue chaotic behaviour even in the presence of gain/loss and nonlinearity, which often assume adversarial roles. Quite recently, notions of parity-time (PT) symmetry have been suggested in photonic settings as a means to enforce stable energy flow in platforms that simultaneously employ both amplification and attenuation. Here we report the experimental observation of optical solitons in PT-symmetric lattices. Unlike other non-conservative nonlinear arrangements where self-trapped states appear as fixed points in the parameter space of the governing equations, discrete PT solitons form a continuous parametric family of solutions. The possibility of synthesizing PT-symmetric saturable absorbers, where a nonlinear wave finds a lossless path through an otherwise absorptive system is also demonstrated.