1,791 research outputs found
Spin gap behavior in CuScGeO by Sc nuclear magnetic resonance
We report the results of a Sc nuclear magnetic resonance (NMR) study
on the quasi-one-dimensional compound CuScGeO at
temperatures between 4 and 300 K. This material has been a subject of current
interest due to indications of spin gap behavior. The temperature-dependent NMR
shift exhibits a character of low-dimensional magnetism with a negative broad
maximum at 170 K. Below , the NMR shifts and
spin lattice relaxation rates clearly indicate activated responses, confirming
the existence of a spin gap in CuScGe% O. The experimental
NMR data can be well fitted to the spin dimer model, yielding a spin gap value
of about 275 K which is close to the 25 meV peak found in the inelastic neutron
scattering measurement. A detailed analysis further points out that the nearly
isolated dimer picture is proper for the understanding of spin gap nature in
CuScGeO.Comment: 4 pages, 6 figures, submitted to Phys. Rev.
Compatible actions and non-abelian tensor products
For a pair of groups we study pairs of actions on and on
such that these pairs are compatible and non-abelian tensor products are defined.Comment: 9 page
Comparative study of thermodynamic properties near the structural phase transitions in Sr3 Rh4 Sn13 and Sr3 Ir4 Sn13
[[abstract]]Structural phase transitions in Sr3Rh4Sn13 and Sr3Ir4Sn13 are currently of interest due to the evidence of strong correlation with their superconductivity. To further obtain additional insight into the thermodynamic properties of the phase transitions, we have performed a study of single-crystalline Sr3Rh4Sn13 and Sr3Ir4Sn13 by means of the specific-heat and thermal-expansion measurements, mainly focusing on the features around the phase-transition temperature T∗≃138 and 147 K, respectively. In particular, the specific-heat data have been analyzed in the framework of the critical fluctuation model in addition to a mean-field contribution. Relatively large critical exponents were obtained for Sr3Ir4Sn13, suggesting a shorter coherence length associated with the phase transition. For each compound, an enhancement in the mean-field jump compared to the BCS value has been quantitatively identified, revealing the strong-coupling characteristics for the observed phase transitions. Furthermore, prominent changes in the coefficient of linear thermal expansion and bulk modulus across T∗ have been identified, providing new information about the structural phase transitions in the title compounds.[[notice]]補正完
Tracking intracavernously injected adipose-derived stem cells to bone marrow.
The intracavernous (i.c.) injection of stem cells (SCs) has been shown to improve erectile function in various erectile dysfunction (ED) animal models. However, the tissue distribution of the injected cells remains unknown. In this study we tracked i.c.-injected adipose-derived stem cells (ADSCs) in various tissues. Rat paratesticular fat was processed for ADSC isolation and culture. The animals were then subject to cavernous nerve (CN) crush injury or sham operation, followed by i.c. injection of 1 million autologous or allogeneic ADSCs that were labeled with 5-ethynyl-2-deoxyuridine (EdU). Another group of rats received i.c. injection of EdU-labeled allogeneic penile smooth muscle cells (PSMCs). At 2 and 7 days post injection, penises and femoral bone marrow were processed for histological analyses. Whole femoral bone marrows were also analyzed for EdU-positive cells by flow cytometry. The results show that ADSCs exited the penis within days of i.c. injection and migrated preferentially to bone marrow. Allogenicity did not affect the bone marrow appearance of ADSCs at either 2 or 7 days, whereas CN injury reduced the number of ADSCs in bone marrow significantly at 7 but not 2 days. The significance of these results in relation to SC therapy for ED is discussed
Gravitational Leakage into Extra Dimensions: Probing Dark Energy Using Local Gravity
The braneworld model of Dvali-Gabadadze-Porrati (DGP) is a theory where
gravity is modified at large distances by the arrested leakage of gravitons off
our four-dimensional universe. Cosmology in this model has been shown to
support both "conventional" and exotic explanations of the dark energy
responsible for today's cosmic acceleration. We present new results for the
gravitational field of a clustered matter source on the background of an
accelerating universe in DGP braneworld gravity, and articulate how these
results differ from those of general relativity. In particular, we show that
orbits nearby a mass source suffer a universal anomalous precession as large as
5 microarcseconds/year, dependent only on the graviton's effective linewidth
and the global geometry of the full, five-dimensional universe. Thus, this
theory offers a local gravity correction sensitive to factors that dictate
cosmological history.Comment: 18 pages, 1 figure, revtex. Reference updated. Footnote change
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