Inverted orbital polarization in strained correlated oxide films

Manipulating the orbital occupation of valence electrons via epitaxial strain in an effort to induce new functional properties requires considerations of how changes in the local bonding environment affect the band structure at the Fermi level. Using synchrotron radiation to measure the x-ray linear dichroism of epitaxially strained films of the correlated oxide CaFeO3, we demonstrate that the orbital polarization of the Fe valence electrons is opposite from conventional understanding. Although the energetic ordering of the Fe 3d orbitals is confirmed by multiplet ligand field theory analysis to be consistent with previously reported strain-induced behavior, we find that the nominally higher energy orbital is more populated than the lower. We ascribe this inverted orbital polarization to an anisotropic bandwidth response to strain in a compound with nearly filled bands. These findings provide an important counterexample to the traditional understanding of strain-induced orbital polarization and reveal a new method to engineer otherwise unachievable orbital occupations in correlated oxides

The GPS craze: six questions to address before deciding to deploy GPS technology on wildlife

GPS and satellite technology for studies on wildlife have improved substantially over the past decade. It is now possible to collect fine-scale location data from migratory animals, animals that have previously been too small to deploy GPS devices on, and other difficult-to-study species. Often researchers and managers have formatted well-defined ecological or conservation questions prior to deploying GPS on animals, whereas other times it is arguably done simply because the technology is now available to do so. We review and discuss six important interrelated questions that should be addressed when planning a study requiring location data. Answers will clarify whether GPS technology is required and whether its use would increase efficiency of data collection and learning from location data. Specifically, what are required: (1) ecological question(s); (2) frequency and duration of data collection; (3) sample size; (4) hardware (VHF or GPS or satellite) and accessories; (5) environmental data; and (6) data-management and analysis procedures? This approach increases the chance that the appropriate technology will be deployed, budgets will be realistic, and data will be sufficient (but not excessive) to answer the ecological questions of interest. The expected results are important advances in ecological science and evidence-based management decisions

Hand controller commonality evaluation process

Hand controller selection for NASA's Orbiter and Space Station Freedom is an important area of human-telerobot interface design and evaluation. These input devices will control remotely operated systems that include large crane-like manipulators (e.g., Remote Manipulator System or RMS), smaller, more dexterous manipulators (e.g., Flight Telerobotic Servicer or FTS), and free flyers (e.g., Orbital Maneuvering Vehicle or OMV). Candidate hand controller configurations for these systems vary in many ways: shape, size, number of degrees-of-freedom (DOF), operating modes, provision of force reflection, range of movement, and 'naturalness' of use. Unresolved design implementation issues remain, including such topics as how the current Orbiter RMS rotational and translational rate hand controllers compare with the proposed Space Station Freedom hand controllers, the advantages that position hand controllers offer for these applications, and whether separate hand controller configurations are required for each application. Since previous studies contain little empirical hand controller task performance data, a controlled study is needed that tests Space Station Freedom candidate hand controllers during representative tasks. This study also needs to include anthropometric and biomechanical considerations

Reliability of Unilateral Isometric and Dynamic Leg Press Force and Power

Strength and power are critical components of athletic performance. Athletes commonly perform sport-specific movements off a single leg, but there are few reliable, easily administered unilateral leg force and power assessments. PURPOSE: To determine 1) the reliability of unilateral leg press maximal isometric force (MIF) and peak power tests and 2) the percentage of MIF that elicits unilateral peak power during a dynamic throw. We hypothesized that the tests would be reliable for the assessment of unilateral MIF and peak power and that unilateral peak power would be achieved at 50% of MIF. METHODS: Eighteen apparently healthy, recreationally active adults (17M: 1F; 27.4 ± 5.0 years; 1.78 ± 0.01 m; 93.5 ± 22.5 kg; 3159 ± 807 N bilateral MIF) completed three testing sessions. After a brief standardized warm-up, each subject performed three maximal unilateral isometric leg presses (MIF) with each leg at 90° of knee flexion on a modified leg press sled equipped with a force plate, linear encoder, and magnetic brake. Subsequently, the sled was unlocked and loaded in ascending fashion with 30%, 40%, 50%, 60%, and 70% of MIF; with an initial knee angle of 90°, subjects used maximal effort to throw each load twice, unilaterally, with each leg. Subjects rested and reset for 10-30 s between efforts. Data were sampled at 300 Hz, low pass filtered at 4 Hz, and peak instantaneous power (W) was calculated for each throw using the measured sled force and velocity. Intraclass correlation coefficients (ICC) were computed for the highest force and power repetition at each load across the three sessions. The ICC (95% CI) and peak power output were determined for both right and left legs. ICCs were considered excellent if ≥ 0.95, high if ≥ 0.90, good if ≥ 0.80, fair if ≥ 0.70, poor if ≤ 0.70, and very poor if ≤ 0.40. RESULTS: MIF showed good reliability between sessions [ICC: 0.85 (0.62, 0.94; left leg); 0.86 (0.58, 0.95; right leg)]. Unilateral peak power also showed good to high reliability between sessions across all loads: ICC (left leg) 30%: 0.91 (0.81, 0.96); 40%: 0.91 (0.81, 0.96); 50%: 0.95 (0.88, 0.98); 60%: 0.93 (0.86, 0.97); 70%: 0.81 (0.64, 0.92); (right leg) 30%: 0.95 (0.89, 0.98); 40%: 0.94 (0.87, 0.97); 50%: 0.92 (0.84, 0.97); 60%: 0.92 (0.84, 0.97); 70%: 0.90 (0.80, 0.96). Across all three sessions, peak power by the left leg was achieved at: 30% (11 of 18 participants); 40% (6 of 18); 50% (1 of 18). Peak power by the right leg was achieved at: 30% (13 of 18 participants); 40% (4 of 18); 50% (1 of 18). CONCLUSION: Unilateral leg press MIF and peak power can be reliably assessed with a modified leg press equipped with a force plate, linear encoder, and magnetic brake in a recreationally active population. Sport teams and coaches can use single leg isometric presses and throws as reliable methods to test their athletes’ unilateral force and peak power, respectively, with loads of 30-50% MIF appropriate for peak power measurement

Dual-stage structural response to quenching charge order in magnetite

The Verwey transition in magnetite (Fe3O4 ) is the prototypical metal-insulator transition and has eluded a comprehensive explanation for decades. A major element of the challenge is the complex interplay between charge order and lattice distortions. Here we use ultrafast electron diffraction (UED) to disentangle the roles of charge order and lattice distortions by tracking the transient structural evolution after charge order is melted via ultrafast photoexcitation. A dual stage response is observed in which X3, X1, and Delta5 type structural distortions occur on markedly different timescales of 0.7 to 3.2 ps and longer than 3.2 ps. We propose that these distinct timescales arise because X3 type distortions strongly couple to the trimeron charge order, whereas the Delta5-distortions are more strongly associated with monoclinic to cubic distortions of the overall lattice. Our work aids in clarifying the charge lattice interplay using UED method and illustrates the disentanglement of the complex phases in magnetite.Comment: 7 figures and 7 table