Effect of a period of cervical flexion on upper extremity muscle strength

Background: Technology is prevalent in almost every aspect of life, from handheld phones to computers. Increases in cervical flexion can cause a strain on the neck and muscles of the upper extremity. Objective: To examine the effect of 30 minutes of cervical flexion at 45 degrees. It was hypothesized that muscle strength will decrease after flexion, and there would be no significant differences between dominant and nondominant arms or genders. Study design: Twenty-four participants (12 male, 12 female) (n = 24; height = 173.1 + 9.3 cm; weight = 73.33 + 22.58kg) were measured before and after cervical flexion using a MicroFET2 Hand Held Digital Muscle Tester to test the middle deltoid, biceps brachii, and triceps brachii of each arm. Results: Compared to pre-measures significant differences were found in both middle deltoids and both biceps brachii, but not in either triceps brachii (p < 0.05). Overall no limited significant differences were found between genders of muscles of either arm. Significant differences (p < 0.05) were found in the dominant biceps brachii, non-dominant biceps brachii, dominant triceps brachii, dominant deltoid, and non-dominant deltoid. Conclusion: These results suggest that a normal daily degree of cervical flexion will decrease some upper extremity strength over the course of 30 minutes

Nitrous oxide and methane in the Atlantic Ocean between 50 degrees North and 52 degrees South: Latitudinal distribution and sea-to-air flux

We discuss nitrous oxide (N2O) and methane (CH4) distributions in 49 vertical profiles covering the upper 300 m of the water column along two 13,500 km transects between 50°N and 52°S during the Atlantic Meridional Transect (AMT) programme (AMT cruises 12 and 13). Vertical N2O profiles were amenable to analysis on the basis of common features coincident with Longhurst provinces. In contrast, CH4 showed no such pattern. The most striking feature of the latitudinal depth distributions was a well-defined “plume” of exceptionally high N2O concentrations coincident with very low levels of CH4, located between 23.5°N and 23.5°S; this feature reflects the upwelling of deep waters containing N2O derived from nitrification, as identified by an analysis of N2O, apparent oxygen utilization (AOU) and NO3-, and presumably depleted in CH4 by bacterial oxidation. Sea-to-air emissions fluxes for a region equivalent to 42% of the Atlantic Ocean surface area were in the range 0.40–0.68 Tg N2O yr-1 and 0.81–1.43 Tg CH4 yr-1. Based on contemporary estimates of the global ocean source strengths of atmospheric N2O and CH4, the Atlantic Ocean could account for 6–15% and 4–13%, respectively, of these source totals. Given that the Atlantic Ocean accounts for around 20% of the global ocean surface, on unit area basis it appears that the Atlantic may be a slightly weaker source of atmospheric N2O than other ocean regions but it could make a somewhat larger contribution to marine-derived atmospheric CH4 than previously thought

Lessons from a large scale deployment of DGT in the Seine basin

Diffusive Gradient in Thin film (DGT) is a speciation technique now commonly used in the scientific literature to assess metallic contamination in water. However applications usually take place in a same watercourse or in neighbouring sites. We propose here to present the first results of a large scale deployment of DGTs. The main objective of the project, which is supported by the French water agency of the Seine-Normandie basin, is to evaluate the potential of passive samplers as monitoring tools. DGT devices were deployed in 45 sites, on 30 locations in the entire Seine river basin. The sampling area was 500 km long and 200 km wide around Paris. The total sampling period lasted over the whole 2009 year. Restricted gels of 0.78 were used to measure labile Cd, Cr, Co, Cu, Mn, Ni, Pb and Zn. In parallel, raw and filtered water samples were collected to measure total and dissolved metals. General physico-chemical parameters were also measured. The whole set of measurements constitute a rich dataset including large and small rivers, and reference as well as impacted sites. The results first allow us to draw a map of total, dissolved and labile metal concentrations, representing the spatial variability of metal contamination in the Seine basin. Moreover, considering the temporal variability, different behaviours, depending on the metal, can be identified. The large scale deployment of DGT in the Seine river basin was successful: all the samples have been interpreted and are exploitable, whereas the dissolved metal samples are sometimes under the detection limit. We have then built a representative data set on the water contamination in labile metal of an urban impacted basin. The results are also interpreted as labile percentage, showing the operationally possible values of lability in contrasted environmental conditions. A first approach of the factors influencing the lability highlights the significance of the nature of the organic matter to interpret the lability of the metals

Epitaxial strain, metastable structure, and magnetic anisotropy in Co‐based superlattices (invited)

We explore the relationship between interface structure and magnetic anisotropy in three types of Co‐based superlattices: Cohcp‐Au; Cofcc‐Cu; and Cohcp‐Cr, grown epitaxially on GaAs(110). For very thin layers of Co, Co‐Au, and Co‐Cu superlattices exhibit a perpendicular easy axis due to magnetoelastic contributions to the anisotropy energy. The magnetic anisotropy in Co‐Cr is found to be strongly dependent on growth conditions. At slow deposition rates of Co the interface between Co and Cr becomes diffuse as is evidenced by a low saturation moment and a shift toward perpendicular anisotropy whereas samples with abrupt interfaces show predominantly parallel anisotropy. The Cr layers grow in a metastable hcp phase which appears to be paramagnetic. The results illustrate the influence of the heterointerface on magnetic properties.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/69828/2/JAPIAU-70-10-5775-1.pd

Superconductivity in novel Ge-based skutterudites: {Sr,Ba}Pt_4Ge_{12}

Combining experiments and ab initio models we report on $\rm SrPt_4Ge_{12}$ and $\rm BaPt_4Ge_{12}$ as members of a novel class of superconducting skutterudites, where Sr or Ba atoms stabilize a framework entirely formed by Ge-atoms. Below $T_c=5.35$ K, and 5.10 K for $\rm BaPt_4Ge_{12}$ and $\rm SrPt_4Ge_{12}$, respectively, electron-phonon coupled superconductivity emerges, ascribed to intrinsic features of the Pt-Ge framework, where Ge-$p$ states dominate the electronic structure at the Fermi energy.Comment: 4 pages, 4 figures, accepted for publication in PR

How should we interpret the two transport relaxation times in the cuprates ?

We observe that the appearance of two transport relaxation times in the various transport coefficients of cuprate metals may be understood in terms of scattering processes that discriminate between currents that are even, or odd under the charge conjugation operator. We develop a transport equation that illustrates these ideas and discuss its experimental and theoretical consequences.Comment: 19 pages, RevTeX with 8 postscript figures included. To appear in ``Non Fermi Liquid Physics'', J. Phys:Cond. Matt. (1997

Observation of Magnetic Flux Generated Spontaneously During a Rapid Quench of Superconducting Films

We report observations of spontaneous formation of magnetic flux lines during a rapid quench of YBa$_{2}$Cu$_{3}$O$_{7-\delta}$ films through T$_{c}$. This effect is predicted according to the Kibble-Zurek mechanism of creation of topological defects of the order parameter during a symmetry-breaking phase transition. Our previous experiment, at a quench rate of 20K/sec, gave null results. In the present experiment, the quench rate was increased to \TEXTsymbol{>} 10$^{8}$ K/sec. Within experimental resolution, the dependence of the measured flux on the cooling rate is consistent with the prediction

Structure inhomogeneities, shallow defects, and charge transport in the series of thermoelectric materials K2Bi8−xSbxSe13

The charge transport properties of the low-dimensional thermoelectric materials K2Bi8-xSbxSe13 (02Bi8-xSbxSe13 was analyzed on the basis of the classical semiconductor theory and discussed in the context of recent band calculations. The results suggest that the K2Bi8-xSbxSe13 materials possess coexisting domains with semimetallic and semiconducting characters whose ratio is influenced by the value of x and by local defects. The extent and relative distribution of these domains control the charge transport properties. Electron diffraction experiments performed on samples of K2Bi8-xSbxSe13 with x=1.6 show evidence for such domains by indicating regions with long range ordering of K+/Bi3+ atoms and regions with increased disorder. The semiconducting behavior is enhanced with increasing x (i.e., Sb/Bi ratio) in the composition through a decrease of the semimetallic fraction

Temperature dependence of the magnetization reversal in Co(fcc)–BN–Co(poly hcp) structures

The magnetic properties of multilayer structures with two magnetic layers of the same metal (Co) but with different crystallographic structures separated by an insulating BN layer have been studied. These structures were prepared on Si (001) substrates by a combination of molecular beam epitaxy (metallic layers) and electron cyclotron resonance-assisted sputtering (BN layer). An fcc Co single-crystal layer (60 Å) was first stabilized by growing it on a copper fcc buffer layer and subsequently a polycrystalline Co layer (70 Å) with hcp structure was grown on top of the insulating BN layer. A CoO antiferromagnetic layer, formed adjacent to this hcp Co layer, significantly influenced the magnetic behavior of the polycrystalline hcp Co layer. The magnetic hysteresis loops for these structures were measured at temperatures ranging from 5 to 350 K with the magnetic field applied along the easy (110) in-plane axis of the fcc Co. A very sharp flipping of the magnetization was found for the fcc Co layer with a nearly temperature-independent coercive field that increased from 14 mT below 100 K to 16 mT at 300 K. In contrast, the magnetization reversal in the hcp Co layer was smoother and its coercivity varied significantly with temperature depending on the strength of the exchange coupling with the adjacent CoO layer. At 5 K the coercivity was greater than 0.2 T and decreased with increasing temperature, becoming essentially zero above room temperature. When cooling in a magnetic field, an exchange offset was observed below 150 K that increased to about 0.1 T at 5 K.© 1999 American Institute of Physics.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/70977/2/JAPIAU-85-8-5765-1.pd

Evidence for field-induced excitations in low-temperature thermal conductivity of Bi_2Sr_2CaCu_2O_8

The thermal conductivity ,$\kappa$, of Bi_2Sr_2CaCu_2O_8 was studied as a function of magnetic field. Above 5 K, after an initial decrease, $\kappa(H)$ presents a kink followed by a plateau, as recently reported by Krishana et al.. By contrast, below 1K, the thermal conductivity was found to \emph{increase} with increasing field. This behavior is indicative of a finite density of states and is not compatible with the existence of a field-induced fully gapped $d_{x^{2}-y^{2}}+id_{xy}$ state which was recently proposed to describe the plateau regime. Our low-temperature results are in agreement with recent works predicting a field-induced enhancement of thermal conductivity by Doppler shift of quasi-particle spectrum.Comment: 4 pages including 4 eps figures, submitted to Phys. Rev. Let