Tunable steady-state domain wall oscillator with perpendicular magnetic anisotropy

We theoretically study domain wall oscillations upon the injection of a dc current through a geometrically constrained wire with perpendicular magnetic anisotropy. The oscillation frequency spectrum can be tuned by the injected current density, but additionally by the application of an external magnetic field independent of the power. The results of analytical calculations are supported by micromagnetic simulations based on the Landau-Lifshitz-Gilbert equation. The simple concept of our localized steady-state oscillator might prove useful as a nanoscale microwave generator with possible applications in telecommunication or for rf-assisted writing in magnetic hard drives.Comment: 10 pages, 3 figure

The Vibrational Spectrum of the hydrated Alanine-Leucine Peptide in the Amide region from IR experiments and First Principles Calculation

We have combined infrared (IR) experiments with molecular dynamics (MD) simulations in solution at finite temperature to analyse the vibrational signature of the small floppy peptide Alanine-Leucine. IR spectra computed from first- principles MD simulations exhibit no distinct differences between conformational clusters of alpha-helix/beta-sheet-like folds with different orientations of the bulky leucine side chain. All computed spectra show two prominent bands, in good agreement with the experiment, that are assigned to the stretch vibrations of the carbonyl and carboxyl group, respectively. Variations in band widths and exact maxima are likely due to small fluctuations in the backbone torsion angles

Age and Intrinsic Fitness Affect the Female Rotator Cuff Tendon Tissue

The risk of the development of tendon disorders or ruptures increases with age, but it is unclear whether intrinsic fitness during lifetime might also affect tendon properties. To investigate this, a contrasting rat model of high-capacity runners (HCR with high intrinsic fitness) and low-capacity runners (LCR with low intrinsic fitness) was employed. Histological and molecular changes in rotator cuff (RC) tendons from 10 weeks old (young; HCR-10 and LCR-10) and 100 weeks old (old; HCR-100 and LCR-100) female rats were investigated. Age-dependent changes of RC tendons observed in HCR and LCR were increase of weight, decrease of tenocytes and RNA content, reduction of the wavy pattern of collagen and elastic fibers, repressed expression of Col1a1 , Eln , Postn , Tnmd , Tgfb3 and Egr1 and reduction of the Col1 : Col3 and Col1 : Eln ratio. The LCR rats showed less physical activity, increased body weight, signs of metabolic disease and a reduced life expectancy. Their RC tendons revealed increased weight (more than age-dependent) and enlargement of the tenocyte nuclei (consistent with degenerative tendons). Low intrinsic fitness led to repressed expression of a further nine genes ( Col3a1 , Fbn1 , Dcn , Tnc , Scx , Mkx , Bmp1 , Tgfb1 , Esr1 ) as well as the rise of the Col1 : Col3 and Col1:Eln ratios (related to the lesser expression of Col3a1 and Eln ). The intrinsic fitness influences the female RC tendons at least as much as age. Lower intrinsic fitness accelerates aging of RC tendons and leads to further impairment; this could result in decreased healing potential and elasticity and increased stiffness

Domain-wall depinning assisted by pure spin currents

We study the depinning of domain walls by pure diffusive spin currents in a nonlocal spin valve structure based on two ferromagnetic permalloy elements with copper as the nonmagnetic spin conduit. The injected spin current is absorbed by the second permalloy structure with a domain wall and from the dependence of the wall depinning field on the spin current density we find an efficiency of 6*10^{-14}T/(A/m^2), which is more than an order of magnitude larger than for conventional current induced domain wall motion. Theoretically we reproduce this high efficiency, which arises from the surface torques exerted by the absorbed spin current that lead to efficient depinning.Comment: 11 pages, 3 figures, accepted for publication in Phys. Rev. Let

Purification and Reconstitution of the Glutamate Carrier GltT of the Thermophilic Bacterium Bacillus stearothermophilus

An affinity tag consisting of six adjacent histidine residues followed by an enterokinase cleavage site was genetically engineered at the N-terminus of the glutamate transport protein GltT of the thermophilic bacterium Bacillus stearothermophilus. The fusion protein was expressed in Escherichia coli and shown to transport glutamate. The highest levels of expression were observed in E. coli strain DH5α grown on rich medium. The protein could be purified in a single step by Ni2+-NTA affinity chromatography after solubilization of the cytoplasmic membranes with the detergent Triton X100. Purified GltT was reconstituted in an active state in liposomes prepared from E. coli phospholipids. The protein was reconstituted in detergent-treated preformed liposomes, followed by removal of the detergent with polystyrene beads. Active reconstitution was realized with a wide range of Triton X100 concentrations. Neither the presence of glycerol, phospholipids, nor substrates of the transporter was necessary during the purification and reconstitution procedure to keep the enzyme in an active state. In B. stearothermophilus, GltT translocates glutamate in symport with protons or sodium ions. In membrane vesicles derived from E. coli cells expressing GltT, the Na+ ion dependency seems to be lost, suggesting a role for the lipid environment in the cation specificity. In agreement with the last observation, glutamate transport catalyzed by purified GltT reconstituted in E. coli phospholipid is driven by an electrochemical gradient of H+ but not of Na+.

Relationship between nonadiabaticity and damping in permalloy studied by current induced spin structure transformations

By direct imaging we determine spin structure changes in Permalloy wires and disks due to spin transfer torque as well as the critical current densities for different domain wall types. Periodic domain wall transformations from transverse to vortex walls and vice versa are observed, and the transformation mechanism occurs by vortex core displacement perpendicular to the wire. The results imply that the nonadiabaticity parameter β does not equal the damping α, in agreement with recent theoretical predictions. The vortex core motion perpendicular to the current is further studied in disks revealing that the displacement in opposite directions can be attributed to different polarities of the vortex core

SMARTER Teamwork: System for Management, Assessment, Research, Training, Education, and Remediation for Teamwork

SMARTER Teamwork: System for Management, Assessment, Research, Training, Education, and Remediation for TeamworkThe rapid adoption of Team-Maker and the Comprehensive Assessment of Team MemberEffectiveness (CATME) tools for team formation and peer evaluation make it possible to extendtheir success to have a significant impact on the development of team skills in higher education.The web-based systems have been used by more than 110,000 students of more than 2400faculty at more than 500 institutions internationally—the figure below shows the growth of theuser base. 2400 The system has had 113,373 unique student users. 2200 Fitted curves are third order. 2000 1800 Faculty and staff 1600 1400 1200 Number of 1000 users 800 Institutions 600 400 Aug Oct. 2005 2012 200 0 0 1 2 3 4 5 6 7 Years since software was releasedThis paper and its accompanying poster will describe strategies for broadening the scope of thosetools into a complete system for the management of teamwork in undergraduate education. TheSystem for the Management, Assessment, Research, Training, Education, and Remediation ofTeamwork (SMARTER Teamwork) has three specific goals: 1) to equip students to work inteams by providing them with training and feedback, 2) to equip faculty to manage student teamsby providing them with information and tools to facilitate best practices, and 3) to equipresearchers to understand teams by broadening the system’s capabilities to collect additionaltypes of data so that a wider range of research questions can be studied through a secureresearcher interface. The three goals of the project support each other in hierarchical fashion:research informs faculty practice, faculty determine the students’ experience, which, if wellmanaged based on research findings, equips students to work in teams. Our strategies forachieving these goals are based on a well-accepted training model that has five elements:information, demonstration, practice, feedback, and remediation.The paper that will be submitted and the poster presented at the conference will focus on newfeatures of the system, the development of training materials, and the deployment of a partnerwebsite that shares information about the SMARTER tools for teamwork and provides basicinformation about teamwork and team management

Paternal Diet Defines Offspring Chromatin State and Intergenerational Obesity

The global rise in obesity has revitalized a search for genetic and epigenetic factors underlying the disease. We present a Drosophila model of paternal-diet-induced intergenerational metabolic reprogramming (IGMR) and identify genes required for its encoding in offspring. Intriguingly, we find that as little as 2 days of dietary intervention in fathers elicits obesity in offspring. Paternal sugar acts as a physiological suppressor of variegation, desilencing chromatin-state-defined domains in both mature sperm and in offspring embryos. We identify requirements for H3K9/K27me3-dependent reprogramming of metabolic genes in two distinct germline and zygotic windows. Critically, we find evidence that a similar system may regulate obesity susceptibility and phenotype variation in mice and humans. The findings provide insight into the mechanisms underlying intergenerational metabolic reprogramming and carry profound implications for our understanding of phenotypic variation and evolution

AEGIS at CERN: Measuring Antihydrogen Fall

The main goal of the AEGIS experiment at the CERN Antiproton Decelerator is the test of fundamental laws such as the Weak Equivalence Principle (WEP) and CPT symmetry. In the first phase of AEGIS, a beam of antihydrogen will be formed whose fall in the gravitational field is measured in a Moire' deflectometer; this will constitute the first test of the WEP with antimatter.Comment: Presented at the Fifth Meeting on CPT and Lorentz Symmetry, Bloomington, Indiana, June 28-July 2, 201