Itinerant magnetism in metallic CuFe2Ge2

Theoretical calculations are performed to understand the electronic structure and magnetic properties of CuFe$_2$Ge$_2$. The band structure reveal large electron density $N(E_F)$ at the Fermi level suggesting strong itinerant character of magnetism. The Fermi surface is dominated by two dimensional sheet like structures, with potentially strong nesting between them. The magnetic ground state appears to be ferromagnetic along $a$ and antiferromagnetic in other directions. The results show that CuFe$_2$Ge$_2$ is an antiferromagnetic metal, with similarities to the Fe-based superconductors; such as magnetism with substantial itinerant character and coupling between magnetic order and electrons at the Fermi energy.Comment: 5 pages, 6 figure

Magnetic properties of Mn-doped Ge46 and Ba8Ge46 clathrates

We present a detailed study of the magnetic properties of unique cluster assembled solids namely Mn doped Ge46 and Ba8Ge46 clathrates using density functional theory. We find that ferromagnetic (FM) ground states may be realized in both the compounds when doped with Mn. In Mn2Ge44, ferromagnetism is driven by hybridization induced negative exchange splitting, a generic mechanism operating in many diluted magnetic semiconductors. However, for Mn-doped Ba8Ge46 clathrates incorporation of conduction electrons via Ba encapsulation results in RKKY-like magnetic interactions between the Mn ions. We show that our results are consistent with the major experimental observations for this system.Comment: 6 pages, 4 figure

A study to evaluate the effect of mirror therapy on upper extremity motor functions in stroke patients.

INTRODUCTION : Mirror therapy is relatively new therapeutic intervention for stroke patients. It is a simple, inexpensive and, most importantly, patientdirected treatment that may improve upper-extremity function. It involves performing movements of unimpaired limb while watching its mirror reflection superimposed over the (unseen) impaired limb (motor imagery). It creates a visual illusion of enhanced movement capability of the impaired limb. AIM AND OBJECTIVE : To evaluate the effect of Mirror therapy on upper extremity motor functions in stroke patients. METHODS : 22 patients with one attack of stroke, duration of illness between 2 to 12 months and brunnstrom stage of motor recovery between 1 to 3 with no cognitive impairment (MMSE>23). Patients were randomly divided into 2 groups: Group A and Group B. Patients in group A were treated with Mirror therapy and conventional therapy; where as in group B, patients were treated with placebo Mirror therapy and conventional therapy. ARAT and FGMR were used to assess motor functions before and after intervention. RESULT : Then data was tabulated and analyzed statistically. Paired and unpaired t-tests were used to evaluate effect of interventions in both groups and the effect of mirror therapy on upper extremity motor functions compared to control group respectively. The analysis leads to inference that mirror therapy along with conventional therapy showed batter result when compared to intervention in control group. Mirror therapy was found to be effective in improving upper extremity motor functions in stroke patients. CONCLUSION : This study concludes that Mirror therapy improves upper extremity motor functions in stroke patients

Growth and Characterization of Ce- Substituted Nd2Fe14B Single Crystals

Single crystals of (Nd1-xCex)2Fe14B are grown out of Fe-(Nd,Ce) flux. Chemical and structural analysis of the crystals indicates that (Nd1-xCex)2Fe14B forms a solid solution until at least x = 0.38 with a Vegard-like variation of the lattice constants with x. Refinements of single crystal neutron diffraction data indicate that Ce has a slight site preference (7:3) for the 4g rare earth site over the 4f site. Magnetization measurements show that for x = 0.38 the saturation magnetization at 400 K, a temperature important to applications, falls from 29.8 for the parent Nd2Fe14B to 27.6 (mu)B/f.u., the anisotropy field decreases from 5.5 T to 4.7 T, and the Curie temperature decreases from 586 to 543 K. First principles calculations carried out within density functional theory are used to explain the decrease in magnetic properties due to Ce substitution. Though the presence of the lower-cost and more abundant Ce slightly affects these important magnetic characteristics, this decrease is not large enough to affect a multitude of applications. Ce-substituted Nd2Fe14B is therefore a potential high-performance permanent magnet material with substantially reduced Nd content.Comment: 11 Pages, 8 figures, 5 table

Enhancement of Friction between Carbon Nanotubes: An Efficient Strategy to Strengthen Fibers

Interfacial friction plays a crucial role in the mechanical properties of carbon nanotube based fibers, composites, and devices. Here we use molecular dynamics simulation to investigate the pressure effect on the friction within carbon nanotube bundles. It reveals that the intertube frictional force can be increased by a factor of 1.5 ~ 4, depending on tube chirality and radius, when all tubes collapse above a critical pressure and when the bundle remains collapsed with unloading down to atmospheric pressure. Furthermore, the overall cross-sectional area also decreases significantly for the collapsed structure, making the bundle stronger. Our study suggests a new and efficient way to reinforce nanotube fibers, possibly stronger than carbon fibers, for usage at ambient conditions.Comment: revtex, 5 pages, accepted by ACS Nano 10 Dec 200

Blast phase myeloproliferative neoplasm: Mayo-AGIMM study of 410 patients from two separate cohorts

A total of 410 patients with blast phase myeloproliferative neoplasm (MPN-BP) were retrospectively reviewed: 248 from the Mayo Clinic and 162 from Italy. Median survival was 3.6 months, with no improvement over the last 15 years. Multivariable analysis performed on the Mayo cohort identified high risk karyotype, platelet count < 100 × 109 /L, age > 65 years and transfusion need as independent risk factors for survival. Also in the Mayo cohort, intensive chemotherapy resulted in complete remission (CR) or CR with incomplete count recovery (CRi) rates of 35 and 24%, respectively; treatment-specified 3-year/5-year survival rates were 32/10% for patients receiving allogeneic stem cell transplant (AlloSCT) (n = 24), 19/13% for patients achieving CR/CRi but were not transplanted (n = 24), and 1/1% in the absence of both AlloSCT and CR/CRi (n = 200) (p < 0.01). The survival impact of AlloSCT (HR 0.2, 95% CI 0.1–0.3), CR/CRi without AlloSCT (HR 0.3, 95% CI 0.2–0.5), high risk karyotype (HR 1.6, 95% CI 1.1–2.2) and platelet count < 100 × 109 /L (HR 1.6, 95% CI 1.1–2.2) were confirmed to be interindependent. Similar observations were made in the Italian cohort. The current study identifies the setting for improved short-term survival in MPN-BP, but also highlights the limited value of current therapy, including AlloSCT, in securing long-term survival

Gate-tunable giant nonreciprocal charge transport in noncentrosymmetric oxide interfaces

A polar conductor, where inversion symmetry is broken, may exhibit directional propagation of itinerant electrons, i.e., the rightward and leftward currents differ from each other, when time-reversal symmetry is also broken. This potential rectification effect was shown to be very weak due to the fact that the kinetic energy is much higher than the energies associated with symmetry breaking, producing weak perturbations. Here we demonstrate the appearance of giant nonreciprocal charge transport in the conductive oxide interface, LaAlO3/SrTiO3, where the electrons are confined to two-dimensions with low Fermi energy. In addition, the Rashba spin???orbit interaction correlated with the sub-band hierarchy of this system enables a strongly tunable nonreciprocal response by applying a gate voltage. The observed behavior of directional response in LaAlO3/SrTiO3 is associated with comparable energy scales among kinetic energy, spin???orbit interaction, and magnetic field, which inspires a promising route to enhance nonreciprocal response and its functionalities in spin orbitronics

Towards colloidal spintronics through Rashba spin-orbit interaction in lead sulphide nanosheets

Employing the spin degree of freedom of charge carriers offers the possibility to extend the functionality of conventional electronic devices, while colloidal chemistry can be used to synthesize inexpensive and tuneable nanomaterials. In order to benefit from both concepts, Rashba spin-orbit interaction has been investigated in colloidal lead sulphide nanosheets by electrical measurements on the circular photo-galvanic effect. Lead sulphide nanosheets possess rock salt crystal structure, which is centrosymmetric. The symmetry can be broken by quantum confinement, asymmetric vertical interfaces and a gate electric field leading to Rashba-type band splitting in momentum space at the M points, which results in an unconventional selection mechanism for the excitation of the carriers. The effect, which is supported by simulations of the band structure using density functional theory, can be tuned by the gate electric field and by the thickness of the sheets. Spin-related electrical transport phenomena in colloidal materials open a promising pathway towards future inexpensive spintronic devices.Comment: 25 pages, 4 figure