15,121 research outputs found
Exchange Field-Mediated Magnetoresistance in the Correlated Insulator Phase of Be Films
We present a study of the proximity effect between a ferromagnet and a
paramagnetic metal of varying disorder. Thin beryllium films are deposited onto
a 5 nm-thick layer of the ferromagnetic insulator EuS. This bilayer arrangement
induces an exchange field, , of a few tesla in low resistance Be films
with sheet resistance , where is the quantum resistance.
We show that survives in very high resistance films and, in fact,
appears to be relatively insensitive to the Be disorder. We exploit this fact
to produce a giant low-field magnetoresistance in the correlated insulator
phase of Be films with .Comment: To be published in Physical Review Letter
Structural and Physical Properties of CaFe4As3 Single Crystals
We report the synthesis, and structural and physical properties of CaFe4As3
single crystals. Needle-like single crystals of CaFe4As3 were grown out of Sn
flux and the compound adopts an orthorhombic structure as determined by X-ray
diffraction measurements. Electrical, magnetic, and thermal properties indicate
that the system undergoes two successive phase transitions occurring at TN1 ~
90 K and TN2 ~ 26 K. At TN1, electrical resistivities (\rho(b) and \rho(ac))
are enhanced while magnetic susceptibilities (\chi(b) and \chi(ac)) are reduced
in both directions parallel and perpendicular to the b-axis, consistent with
the scenario of antiferromagnetic spin-density-wave formation. At TN2, specific
heat reveals a slope change, and \chi(ac) decreases sharply but \chi(b) has a
clear jump before it decreases again with decreasing temperature. Remarkably,
both \rho(b) and \rho(ac) decrease sharply with thermal hysteresis, indicating
the first-order nature of the phase transition at TN2. At low temperatures,
\rho(b) and \rho(ac) can be described by {\rho} = {\rho}0 + AT^\alpha ({\rho}0,
A, and {\alpha} are constants). Interestingly, these constants vary with
applied magnetic field. The ground state of CaFe4As3 is discussed.Comment: 15 pages, 8 figures, Submitted to Physical Review
Robust Subjective Visual Property Prediction from Crowdsourced Pairwise Labels.
The problem of estimating subjective visual properties from image and video
has attracted increasing interest. A subjective visual property is useful
either on its own (e.g. image and video interestingness) or as an intermediate
representation for visual recognition (e.g. a relative attribute). Due to its
ambiguous nature, annotating the value of a subjective visual property for
learning a prediction model is challenging. To make the annotation more
reliable, recent studies employ crowdsourcing tools to collect pairwise
comparison labels because human annotators are much better at ranking two
images/videos (e.g. which one is more interesting) than giving an absolute
value to each of them separately. However, using crowdsourced data also
introduces outliers. Existing methods rely on majority voting to prune the
annotation outliers/errors. They thus require large amount of pairwise labels
to be collected. More importantly as a local outlier detection method, majority
voting is ineffective in identifying outliers that can cause global ranking
inconsistencies. In this paper, we propose a more principled way to identify
annotation outliers by formulating the subjective visual property prediction
task as a unified robust learning to rank problem, tackling both the outlier
detection and learning to rank jointly. Differing from existing methods, the
proposed method integrates local pairwise comparison labels together to
minimise a cost that corresponds to global inconsistency of ranking order. This
not only leads to better detection of annotation outliers but also enables
learning with extremely sparse annotations. Extensive experiments on various
benchmark datasets demonstrate that our new approach significantly outperforms
state-of-the-arts alternatives.Comment: 14 pages, accepted by IEEE TPAM
Comment on "Isoelectronic Ru substitution at Fe-site in Sm(FeRu)AsOF compound and its effects on structural, superconducting and normal state properties" (arXiv:1004.1978)
Based on the five-orbital model, we derive the reduced impurity scattering
rate in Sm(FeRu)AsOF
from the residual resistivity. At , the transition temperature is
K. For ) the obtained value
of ranges from 1.5 to 2.9, which suggests that the -wave state
cannot survive. We point out that the magnetoresistance frequently gives an
underestimated value of in correlated electron systems.Comment: 2 page
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Nerve-targeted probes for fluorescence-guided intraoperative imaging.
A fundamental goal of many surgeries is nerve preservation, as inadvertent injury can lead to patient morbidity including numbness, pain, localized paralysis and incontinence. Nerve identification during surgery relies on multiple parameters including anatomy, texture, color and relationship to surrounding structures using white light illumination. We propose that fluorescent labeling of nerves can enhance the contrast between nerves and adjacent tissue during surgery which may lead to improved outcomes. Methods: Nerve binding peptide sequences including HNP401 were identified by phage display using selective binding to dissected nerve tissue. Peptide dye conjugates including FAM-HNP401 and structural variants were synthesized and screened for nerve binding after topical application on fresh rodent and human tissue and in-vivo after systemic IV administration into both mice and rats. Nerve to muscle contrast was quantified by measuring fluorescent intensity after topical or systemic administration of peptide dye conjugate. Results: Peptide dye conjugate FAM-HNP401 showed selective binding to human sural nerve with 10.9x fluorescence signal intensity (1374.44 ± 425.96) compared to a previously identified peptide FAM-NP41 (126.17 ± 61.03). FAM-HNP401 showed nerve-to-muscle contrast of 3.03 ± 0.57. FAM-HNP401 binds and highlight multiple human peripheral nerves including lower leg sural, upper arm medial antebrachial as well as autonomic nerves isolated from human prostate. Conclusion: Phage display has identified a novel peptide that selectively binds to ex-vivo human nerves and in-vivo using rodent models. FAM-HNP401 or an optimized variant could be translated for use in a clinical setting for intraoperative identification of human nerves to improve visualization and potentially decrease the incidence of intra-surgical nerve injury
Effect of synthesized temperature on the assembly and properties of four lanthanide supramolecular frameworks
Four new lanthanide coordination polymers, [H3O][Ln3(HPA)10(H2O)3·2H2O] (Ln = Pr for 1, Ln = Nd for 2), [Ln2(HPA)6(H2O)4·2H2O] (Ln = Sm for 3, Ln = Tb for 4) (HHPA =3-(4-hydroxyphenyl)propanoic acid), were successfully synthesized and characterized. 1 and 2 are isostructural and have 1D metal chain structure, while 3 and 4 show 0D network with binuclear subunits. The results indicated that the effect of reaction temperature can modulate the final structures. The HPA ligands adopt bidentate chelating and tridentate chelating bridging modes to coordinate with Ln(III) ions in 1-4. It has been shown that 4 can act as a fluorescent sensor for highly sensitive detection of nitroaromatics and Fe3+.               KEY WORDS: Sensor, Lanthanide, Structure, Temperature Bull. Chem. Soc. Ethiop. 2019, 33(1), 113-125DOI: https://dx.doi.org/10.4314/bcse.v33i1.1
Magnetic and Transport Properties in (=00.4)
Magnetic and transport properties of () system have been investigated. A broad maximum in M(T) curve,
indicative of low-dimensional antiferromagnetic ordering originated from
layers, is observed in Ca-free sample. With increasing Ca
doping level up to 0.2, the M(T) curve remains almost unchanged, while
resistivity is reduced by three orders. Higher Ca doping level leads to a
drastic change of magnetic properties. In comparison with the samples with
, the temperature corresponding to the maximum of M(T) is much
lowered for the sample =0.3. The sample =0.4 shows a small kink instead
of a broad maximum and a weak ferromagnetic feature. The electrical transport
behavior is found to be closely related to magnetic properties for the sample
=0.2, 0.25, 0.3, 0.4. It suggests that layers are involved
in charge transport in addition to conducting planes to interpret the
correlation between magnetism and charge transport. X-ray photoelectron
spectroscopy studies give an additional evidence of the the transfer of the
holes into the charge reservoir
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