935 research outputs found
GROUND REACTION FORCE AND RATE OF FORCE DEVELOPMENT DURING LOWER BODY RESISTANCE TRAINING EXERCISES
This study quantified the differences in the kinetic profiles of the back squat, deadlift, step-up, and lunge. Eleven subjects performed 2 repetitions of their 5 repetition maximum in each of the 4 exercises. Kinetic data were collected using a force platform. The exercises were compared based on their peak vertical ground reaction force (GRFP) and rate of force development (RFD) in both the eccentric and concentric phase. A repeated measures ANOVA indicated differences (p ≤ 0.001) in GRFP
attained for the different exercises in both the eccentric and concentric phase. No significant differences (p ≥ 0.05) were found for RFD for any of the exercises in either the eccentric or concentric phase. Results can guide the development of training programs that are specific to strength, explosiveness, or osteogenesis
THE TIME COURSE OF RECOVERY FROM A MESOCYCLE OF PERIODIZED PLYOMETRIC TRAINING
This study evaluated the effectiveness of a mesocycle of periodized plyometric training and the influence of the duration of the post training recovery period. All subjects’ countermovement jump height, peak power, and body mass were assessed with a force platform prior to and 2, 4, 6, 8, and 10 days after training. Jump height was 25.0% greater (p ≤ 0.05) after training with no difference (p > 0.05) between the recovery periods of 2, 4, 6, 8, or 10 days. Peak power was 11.6 to 14.3 % greater (p ≤ 0.001) after training for the training group with no difference (p > 0.05) between recovery periods of 2, 4, 6, 8, or 10 days. Periodized plyometric programs with decreasing volume and increasing intensity improve jump performance without a need for a post training recovery period
Electronic tuneability of a structurally rigid surface intermetallic and Kondo lattice: CePt / Pt(111)
We present an extensive study of structure, composition, electronic and
magnetic properties of Ce--Pt surface intermetallic phases on Pt(111) as a
function of their thickness. The sequence of structural phases appearing in low
energy electron diffraction (LEED) may invariably be attributed to a single
underlying intermetallic atomic lattice. Findings from both microscopic and
spectroscopic methods, respectively, prove compatible with CePt formation
when their characteristic probing depth is adequately taken into account. The
intermetallic film thickness serves as an effective tuning parameter which
brings about characteristic variations of the Cerium valence and related
properties. Soft x-ray absorption (XAS) and magnetic circular dichroism (XMCD)
prove well suited to trace the changing Ce valence and to assess relevant
aspects of Kondo physics in the CePt surface intermetallic. We find
characteristic Kondo scales of the order of 10 K and evidence for
considerable magnetic Kondo screening of the local Ce moments.
CePt/Pt(111) and related systems therefore appear to be promising
candidates for further studies of low-dimensional Kondo lattices at surfaces.Comment: 14 pages, 11 figure
Was the GLE on May 17, 2012 linked with the M5.1-class flare the first in the 24th solar cycle?
On May 17, 2012 an M5.1-class flare exploded from the sun. An O-type coronal
mass ejection (CME) was also associated with this flare. There was an instant
increase in proton flux with peak at MeV, leading to S2 solar
radiation storm level. In about 20 minutes after the X-ray emission, the solar
particles reached the Earth.It was the source of the first (since December
2006) ground level enhancement (GLE) of the current solar cycle 24. The GLE was
detected by neutron monitors (NM) and other ground based detectors. Here we
present an observation by the Tupi muon telescopes (Niteroi, Brazil, , , 3 m above sea level) of the enhancement of muons at ground
level associated with this M5.1-class solar flare. The Tupi telescopes
registered a muon excess over background in the 5-min binning time
profile. The Tupi signal is studied in correlation with data obtained by
space-borne detectors (GOES, ACE), ground based neutron monitors (Oulu) and air
shower detectors (the IceTop surface component of the IceCube neutrino
observatory). We also report the observation of the muon signal possibly
associated with the CME/sheath striking the Earth magnetosphere on May 20,
2012. We show that the observed temporal correlation of the muon excess
observed by the Tupi muon telescopes with solar transient events suggests a
real physical connection between them. Our observation indicates that
combination of two factors, the low energy threshold of the Tupi muon
telescopes and the location of the Tupi experiment in the South Atlantic
Anomaly region, can be favorable in the study and detection of the solar
transient events. Our experiment provides new data complementary to other
techniques (space and ground based) in the study of solar physics.Comment: 9 pages, 10 figure
A different look at the spin state of Co ions in CoO pyramidal coordination
Using soft-x-ray absorption spectroscopy at the Co- and O- edges,
we demonstrate that the Co ions with the CoO pyramidal
coordination in the layered SrCoOCl compound are unambiguously in the
high spin state. Our result questions the reliability of the spin state
assignments made so far for the recently synthesized layered cobalt
perovskites, and calls for a re-examination of the modeling for the complex and
fascinating properties of these new materials.Comment: 5 pages 3 figure
Recommended from our members
In situ Raman spectroscopy on silicon nanowire anodes integrated in lithium ion batteries
Rapid decay of silicon anodes during lithiation poses a significant challenge in application of silicon as an anode material in lithium ion batteries. In situ Raman spectroscopy is a powerful method to study the relationship between structural and electrochemical data during electrode cycling and to allow the observation of amorphous as well as liquid and transient species in a battery cell. Herein, we present in situ Raman spectroscopy on high capacity electrode using uncoated and carbon-coated silicon nanowires during first lithiation and delithiation cycle in an optimized lithium ion battery setup and complement the results with operando X-ray reflection diffraction measurements. During lithiation, we were able to detect a new Raman signal at 1859 cm−1 especially on uncoated silicon nanowires. The detailed in situ Raman measurement of the first lithiation/delithiation cycle allowed to differentiate between morphology changes of the electrode as well as interphase formation from electrolyte components
ANTAGONIST CONDITIONING CONTRACTIONS IMPAIR AGONIST FUNCTIONING
This study assessed the effect of antagonist conditioning contractions (ACC) on the subsequent force and electromyography of an agonist. Twelve subjects performed isokinetic elbow flexion on a dynamometer in 4 test conditions including a baseline condition without, and 1, 3 and 6 seconds after, isometric triceps extension. Average peak torque (T), peak torque/body weight (T:BW), average power (P), and rate of torque development (RTD) were assessed. Electromyographic data were obtained from elbow extensors and flexors. A repeated measures ANOVA with post hoc analysis demonstrated that T, T:BW, P, and RTD were higher in the baseline, compared to the post ACC conditions (P ≤ 0.05), and appears to be due to higher brachioradialis activation in the baseline condition in compared to some post ACC conditions (P ≤ 0.05)
Systematics of electronic and magnetic properties in the transition metal doped SbTe quantum anomalous Hall platform
The quantum anomalous Hall effect (QAHE) has recently been reported to emerge
in magnetically-doped topological insulators. Although its general
phenomenology is well established, the microscopic origin is far from being
properly understood and controlled. Here we report on a detailed and systematic
investigation of transition-metal (TM)-doped SbTe. By combining density
functional theory (DFT) calculations with complementary experimental
techniques, i.e., scanning tunneling microscopy (STM), resonant photoemission
(resPES), and x-ray magnetic circular dichroism (XMCD), we provide a complete
spectroscopic characterization of both electronic and magnetic properties. Our
results reveal that the TM dopants not only affect the magnetic state of the
host material, but also significantly alter the electronic structure by
generating impurity-derived energy bands. Our findings demonstrate the
existence of a delicate interplay between electronic and magnetic properties in
TM-doped TIs. In particular, we find that the fate of the topological surface
states critically depends on the specific character of the TM impurity: while
V- and Fe-doped SbTe display resonant impurity states in the vicinity
of the Dirac point, Cr and Mn impurities leave the energy gap unaffected. The
single-ion magnetic anisotropy energy and easy axis, which control the magnetic
gap opening and its stability, are also found to be strongly TM
impurity-dependent and can vary from in-plane to out-of-plane depending on the
impurity and its distance from the surface. Overall, our results provide
general guidelines for the realization of a robust QAHE in TM-doped
SbTe in the ferromagnetic state.Comment: 40 pages, 13 figure
Magnetic Structures of High Temperature Phases of TbBaCo2O5.5
Neutron diffraction studies have been carried out on a single crystal of
oxygen-deficient perovskite TbBaCo2O5.5 in the temperature range of 7-370 K.
There have been observed several magnetic or structural transitions. Among
these, the existence of the transitions to the insulating phase from the
metallic one at ~340 K, to the one with the ferromagnetic moment at ~280 K and
possibly to the antiferromagnetic one at ~260 K, with decreasing temperature T
correspond to those reported in former works. We have studied the magnetic
structures at 270 K and 250 K and found that all Co3+ ions of the CoO6
octahedra are in the low spin state and those of the CoO5 pyramids carry spins
which are possibly in the intermediate spin state. Non-collinear magnetic
structures are proposed at these temperatures. Two other transitions have also
been observed at the temperatures, ~100 K and ~250 K.Comment: 9 pages, 2 tables, 10 figure
- …