Quantm Magnetoresistance of the PrFeAsO oxypnictides

We report the observation of an unusual $B$ dependence of transverse magnetoresistance (MR) in the PrFeAsO, one of the parent compound of pnictide superconductors. Below the spin density wave transition, MR is large, positive and increases with decreasing temperature. At low temperatures, MR increases linearly with $B$ up to 14 T. For $T$$\geq$40 K, MR vs $B$ curve develops a weak curvature in the low-field region which indicates a crossover from $B$ linear to $B^2$ dependence as $B$$\rightarrow$0. The $B$ linear MR originates from the Dirac cone states and has been explained by the quantum mechanical model proposed by Abrikosov.Comment: accepted for publication in Appl. Phys. Let

Magnetoresistance behavior of a ferromagnetic shape memory alloy: Ni_1.75Mn_1.25Ga

A negative-positive-negative switching behavior of magnetoresistance (MR) with temperature is observed in a ferromagnetic shape memory alloy Ni_1.75Mn_1.25Ga. In the austenitic phase between 300 and 120 K, MR is negative due to s-d scattering. Curiously, below 120K MR is positive, while at still lower temperatures in the martensitic phase, MR is negative again. The positive MR cannot be explained by Lorentz contribution and is related to a magnetic transition. Evidence for this is obtained from ab initio density functional theory, a decrease in magnetization and resistivity upturn at 120 K. Theory shows that a ferrimagnetic state with anti-ferromagnetic alignment between the local magnetic moments of the Mn atoms is the energetically favoured ground state. In the martensitic phase, there are two competing factors that govern the MR behavior: a dominant negative trend up to the saturation field due to the decrease of electron scattering at twin and domain boundaries; and a weaker positive trend due to the ferrimagnetic nature of the magnetic state. MR exhibits a hysteresis between heating and cooling that is related to the first order nature of the martensitic phase transition.Comment: 17 pages, 5 figures. Accepted in Phys. Rev.

Authentic Occupational Therapy: A genealogy of normative technology in occupational therapy

Drawing on a Foucauldian genealogical methodology this dissertation critically examines the historical lineage of occupational therapy. During the latter half of the 20th century academics in occupational therapy repeatedly argued that reengagement with the values and beliefs that provided an historical foundation for the profession must occur to ensure that occupational therapy remained relevant and continued to flourish. Critics have also called into question the legitimacy of many of the traditional notions which supported the establishment of occupational therapy at the beginning of the 20th century. In critically examining the moral treatment of the 19th century, occupational therapy practice described as moral treatment in the 20th century, and occupational therapy practice that relates to spirituality, some of the normative assumptions that guide practice in different temporal contexts are explored. Specifically, the genealogical methodology employed helped to outline how particular therapeutic technologies work with normative content. A critical examination of historical and contemporary literature revealed an array of therapeutic techniques that, for better or worse, occupation workers had available to them. Practicing authentically would require occupational therapists to attend to the normative ends of treatment. Concluding arguments highlight the necessity of practice that considers the normative dimensions of occupation and the potential for critical research to help outline limits beyond which occupational therapists risk jeopardizing the wellbeing of clients and communities that seek professional attention

Baryonic hybrids: Gluons as beads on strings between quarks

We analyze the ground state of the heavy-quark hybrid system composed of three quarks and a gluon. The known string tension K and approximately-known gluon mass M lead to a precise specification of the long-range non-relativistic part of the potential binding the gluon to the quarks with no undetermined phenomenological parameters, in the limit of large interquark separation R. Our major tool (also used earlier by Simonov) is the use of proper-time methods to describe gluon propagation within the quark system, which reveals the gluon Wilson line as a composite of co-located quark and antiquark lines. We show that (aside from color-Coulomb and similar terms) the gluon potential energy in the presence of quarks is accurately described via attaching these three strings to the gluon, which in equilibrium sits at the middle of the Y-shaped string network joining the three quarks. The gluon undergoes small harmonic fluctuations that slightly stretch these strings and quasi-confine the gluon to the neighborhood of the middle. In the non-relativistic limit (large R) we use the Schrodinger equation, ignoring mixing with l=2 states. Relativistic corrections (smaller R) are applied with a variational principle for the relativistic harmonic oscillator. We also consider the role of color-Coulomb contributions. We find leading non-relativistic large-R terms in the gluon string energy which behave like the square root of K/(MR). The relativistic energy goes like the cube root of K/R. We get an acceptable fit to lattice data with M = 500 MeV. We show that in the quark-antiquark hybrid the gluon is a bead that can slide without friction on a string joining the quark and anti-quark. We comment briefly on the significance of our findings to fluctuations of the minimal surface.Comment: 18 pages, revtex4 plus 8 .eps figures in one .tar.gz fil

Single Secret Key Crptosystem for Secure and Efficient Exchange of Data in Cloud

Nowadays users are storing their personal data on a cloud storage because of its numerous advantages. One of the important advantage in cloud storage is sharing of data between users or between organizations. In this paper we propose a simple, flexible, efficient and secure data sharing method for the cloud users. Here we are describing a special type of public key encryption scheme where public key, master-secret key, single secret key and cipher text sizes are constant. Single secret key can be obtained by combining number of secret keys. The sender can securely share multiple files with receiver by encrypting each file using a separate public key. Then the sender will combine all the public keys to form a single secret key which is exchanged with receiver by using Diffie-Hellman algorithm. Advantage of small single secret key is user can store this decryption key on a resource constraint devices like smart cards, smart cell phones or sensor nodes. Receiver can download the number of files by using single secret key

James Ricketts to Susan Kean, December 25, 1795

James Ricketts in New York, NY wrote to Susan Kean, unaddressed. Both James and Sarah Ricketts wrote Susan a Christmas Letter about the recent goings on and Susan\u27s decision to leave for New York without Peter. There was a measles outbreak at the time. People included: Mr. Biddle, Mrs. A., Peter Kean, Phil, Hannah, Mrs. L., Cato, Mr. K., Mr. L, Mrs. L. Places Included Camelo at William Street [in NYC].https://digitalcommons.kean.edu/lhc_1790s/1294/thumbnail.jp

Design and Analysis of Centrifugal Impeller

Centrifugal pumps are used widely in different industries for various industrial purposes. Since performance of pump is affected by vibrations and depends on the blade inlet or outlet angle. The performance of the centrifugal pumps can be improved by alternating the geometric characteristics of impeller in the pumps. Centrifugal pump performance mainly depends upon blade exit angle. The vibration is mainly caused by blade exit angle. The rotating of the blade is based on the natural frequency and mode shapes. The impeller chosen for the study was a single- entry impeller with radial vanes. Using Creo 4.0 and ANSYS Workbench software the modeling and simulation of the impeller have been carried out. The respective frequencies and corresponding mode shapes impeller were measured by using eigenvalues and eigenvectors respectively. The results showed that the varying impeller blade exit angle had significant effect on natural frequency of the impeller