13,931 research outputs found
Type II superconductivity in SrPd2Ge2
Previous investigations have shown that SrPd2Ge2, a compound isostructural
with "122" iron pnictides but iron- and pnictogen-free, is a conventional
superconductor with a single s-wave energy gap and a strongly three-dimensional
electronic structure. In this work we reveal the Abrikosov vortex lattice
formed in SrPd2Ge2 when exposed to magnetic field by means of scanning
tunneling microscopy and spectroscopy. Moreover, by examining the differential
conductance spectra across a vortex and estimating the upper and lower critical
magnetic fields by tunneling spectroscopy and local magnetization measurements,
we show that SrPd2Ge2 is a strong type II superconductor with \kappa >>
sqrt(2). Also, we compare the differential conductance spectra in various
magnetic fields to the pair breaking model of Maki - de Gennes for dirty limit
type II superconductor in the gapless region. This way we demonstrate that the
type II superconductivity is induced by the sample being in the dirty limit,
while in the clean limit it would be a type I superconductor with \kappa\ <<
sqrt(2), in concordance with our previous study (T. Kim et al., Phys. Rev. B
85, (2012)).Comment: 9 pages, 4 figure
Anisotropic ferromagnetism in carbon doped zinc oxide from first-principles studies
A density functional theory study of substitutional carbon impurities in ZnO
has been performed, using both the generalized gradient approximation (GGA) and
a hybrid functional (HSE06) as exchange-correlation functional. It is found
that the non-spinpolarized C impurity is under almost all
conditions thermodynamically more stable than the C impurity which
has a magnetic moment of , with the exception of very O-poor
and C-rich conditions. This explains the experimental difficulties in sample
preparation in order to realize -ferromagnetism in C-doped ZnO. From GGA
calculations with large 96-atom supercells, we conclude that two
C-C impurities in ZnO interact ferromagnetically, but
the interaction is found to be short-ranged and anisotropic, much stronger
within the hexagonal -plane of wurtzite ZnO than along the c-axis. This
layered ferromagnetism is attributed to the anisotropy of the dispersion of
carbon impurity bands near the Fermi level for C impurities in
ZnO. From the calculated results, we derive that a C
concentration between 2% and 6% should be optimal to achieve
-ferromagnetism in C-doped ZnO.Comment: 9 pages, 7 figure
Social Workers' Attitudes Towards Public Accountability
The public demand for accountability of human services has been increasing in the United States. Despite the growing importance of public accountability as a special responsibility of social workers, little information is available in U.S. on how these pro fessionals react to the implementation of accountability programs. The survey reported in this paper was made to explore the attitudes of social workers in U.S. hospitals toward PSRO, a nationwide health care service review system. The paper presents a descriptive overview of significant aspects of American social workers' personal attitudes toward various issues of current concern about this accountability system.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/67090/2/10.1177_002087288402700307.pd
The Effects of d_{x^2-y^2}-d_{xy} Mixing on Vortex Structures and Magnetization
The structure of an isolated single vortex and the vortex lattice, and the
magnetization in a -wave superconductor are investigated within a
phenomenological Ginzburg-Landau (GL) model including the mixture of the
-wave and -wave symmetry. The isolated single vortex
structure in a week magnetic field is studied both numerically and
asymptotically. Near the upper critical field , the vortex lattice
structure and the magnetization are calculated analytically.Comment: 14 pages, REVTeX, 2 EPS figures, Journal of Physics: Condensed Matter
(in press
Fragmented and Single Condensate Ground States of Spin-1 Bose Gas
We show that the ground state of a spin-1 Bose gas with an antiferro-
magnetic interaction is a fragmented condensate in uniform magnetic fields. The
number fluctuations in each spin component change rapidly from being enormous
(order ) to exceedingly small (order 1) as the magnetization of the system
increases. A fragmented condensate can be turned into a single condensate state
by magnetic field gradients. The conditions for existence and the method of
detecting fragmented states are presented.Comment: 4 pages, no figure
UBVI Surface Photometry of the Spiral Galaxy NGC 300 in the Sculptor Group
We present UBVI surface photometry for 20.'5 X 20.'5 area of a late-type
spiral galaxy NGC 300. In order to understand the morphological properties and
luminosity distribution characteristics of NGC 300, we have derived isophotal
maps, surface brightness profiles, ellipticity profiles, position angle
profiles, and color profiles. By merging the I-band data of our surface
brightness measurements with those of Boeker et al. (2002) based on Hubble
Space Telescope observations, we have made combined I-band surface brightness
profiles for the region of 0."02 < r < 500" and decomposed the profiles into
three components: a nucleus, a bulge, and an exponential disk.Comment: 16 pages(cjaa209.sty), Accepted by the Chinese J. Astron. Astrophys.,
Fig 2 and 8 are degraded to reduce spac
Design and Construction of a Double Inversion Recombination Switch for Heritable Sequential Genetic Memory
Background: Inversion recombination elements present unique opportunities for computing and information encoding in biological systems. They provide distinct binary states that are encoded into the DNA sequence itself, allowing us to overcome limitations posed by other biological memory or logic gate systems. Further, it is in theory possible to create complex sequential logics by careful positioning of recombinase recognition sites in the sequence. Methodology/Principal Findings: In this work, we describe the design and synthesis of an inversion switch using the fim and hin inversion recombination systems to create a heritable sequential memory switch. We have integrated the two inversion systems in an overlapping manner, creating a switch that can have multiple states. The switch is capable of transitioning from state to state in a manner analogous to a finite state machine, while encoding the state information into DNA. This switch does not require protein expression to maintain its state, and ââremembersâ â its state even upon cell death. We were able to demonstrate transition into three out of the five possible states showing the feasibility of such a switch. Conclusions/Significance: We demonstrate that a heritable memory system that encodes its state into DNA is possible, and that inversion recombination system could be a starting point for more complex memory circuits. Although the circuit di
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