496 research outputs found
Measuring Luttinger Liquid Correlations from Charge Fluctuations in a Nanoscale Structure
We suggest an experiment to study Luttinger liquid behavior in a
one-dimensional nanostructure, avoiding the usual complications associated with
transport measurements. The proposed setup consists of a quantum box, biased by
a gate voltage, and side-coupled to a quantum wire by a point contact. Close to
the degeneracy points of the Coulomb blockaded box, and in the presence of a
magnetic field sufficiently strong to spin polarize the electrons, the setup
can be described as a Luttinger liquid interacting with an effective Kondo
impurity. Using exact nonperturbative techniques we predict that the
differential capacitance of the box will exhibit distinctive Luttinger liquid
scaling with temperature and gate voltage.Comment: REVTeX, 4 pages, 1 figure included. Final version, two references
adde
Evaluation of the Galalpha1-3Gal epitope as a host modification factor eliciting natural humoral immunity to enveloped viruses
Human sera contain high levels of natural antibody (Ab) to Galalpha1-3Gal, a terminal glycosidic structure expressed on the surface of cells of mammals other than Old World primates. Incorporation of this determinant onto retroviral membranes by passage of viruses in cells encoding alpha-1-3-galactosyltransferase (GT) renders retroviruses sensitive to lysis by natural Ab and complement in normal human serum (NHS). Plasma membrane-budding viruses representing four additional virus groups were examined for their sensitivities to serum inactivation after passage through human cell lines that lack a functional GT or human cells expressing recombinant porcine GT. The inactivation of lymphocytic choriomeningitis virus (LCMV) by NHS directly correlated with host modification of the virus via expression of Galalpha1-3Gal and was blocked by incorporation of soluble Galalpha1-3Gal disaccharide into the inactivation assay. GT-deficient mice immunized to make high levels of Ab to Galalpha1-3Gal (anti-Gal Ab) were tested for resistance to LCMV passaged in GT-expressing cells. Resistance was not observed, but in vitro analyses of the mouse immune sera revealed that the antiviral activity of the sera was insufficient to eliminate LCMV infectivity on its natural targets of infection, macrophages, which express receptors for Ab and complement. Newcastle disease virus and vesicular stomatitis virus (VSV) were inactivated by NHS regardless of cell passage history, whereas Sindbis virus (SV) passaged in human cells resisted inactivation. Both VSV and SV passaged in Galalpha1-3Gal-expressing human cells incorporated this sugar moiety onto their major envelope glycoproteins. SV passaged in mouse cells expressing Galalpha1-3Gal was moderately sensitive to inactivation by NHS. These results indicate that enveloped viruses expressing Galalpha1-3Gal differ in their sensitivities to NHS and that a potent complement source, such as that in NHS, is required for efficient inactivation of sensitive viruses in vitro and in vivo
Intrinsic Tunneling in Cuprates and Manganites
The most anisotropic high temperature superconductors like Bi2Sr2CaCu2O8, as
well as the recently discovered layered manganite La1.4Sr1.6Mn2O7 are layered
metallic systems where the interlayer current transport occurs via sequential
tunneling of charge carriers. As a consequence, in Bi2Sr2CaCu2O8 adjacent CuO2
double layers form an intrinsic Josephson tunnel junction while in in
La1.4Sr1.6Mn2O7 tunneling of spin polarized charge carriers between adjacent
MnO2 layers leads to an intrinsic spin valve effect. We present and discuss
interlayer transport experiments for both systems. To perform the experiments
small sized mesa structures were patterned on top of single crystals of the
above materials defining stacks of a small number of intrinsic Josephson
junctions and intrinsic spin valves, respectively.Comment: 6 pages, 8 figure
Image Co-localization by Mimicking a Good Detector's Confidence Score Distribution
Given a set of images containing objects from the same category, the task of
image co-localization is to identify and localize each instance. This paper
shows that this problem can be solved by a simple but intriguing idea, that is,
a common object detector can be learnt by making its detection confidence
scores distributed like those of a strongly supervised detector. More
specifically, we observe that given a set of object proposals extracted from an
image that contains the object of interest, an accurate strongly supervised
object detector should give high scores to only a small minority of proposals,
and low scores to most of them. Thus, we devise an entropy-based objective
function to enforce the above property when learning the common object
detector. Once the detector is learnt, we resort to a segmentation approach to
refine the localization. We show that despite its simplicity, our approach
outperforms state-of-the-art methods.Comment: Accepted to Proc. European Conf. Computer Vision 201
Shape and structure of N=Z 64Ge; Electromagnetic transition rates from the application of the Recoil Distance Method to knock-out reaction
Transition rate measurements are reported for the first and the second 2+
states in N=Z 64Ge. The experimental results are in excellent agreement with
large-scale Shell Model calculations applying the recently developed GXPF1A
interactions. Theoretical analysis suggests that 64Ge is a collective
gamma-soft anharmonic vibrator. The measurement was done using the Recoil
Distance Method (RDM) and a unique combination of state-of-the-art instruments
at the National Superconducting Cyclotron Laboratory (NSCL). States of interest
were populated via an intermediate-energy single-neutron knock-out reaction.
RDM studies of knock-out and fragmentation reaction products hold the promise
of reaching far from stability and providing lifetime information for excited
states in a wide range of nuclei
Observation of isotonic symmetry for enhanced quadrupole collectivity in neutron-rich 62,64,66Fe isotopes at N=40
The transition rates for the 2_{1}^{+} states in 62,64,66Fe were studied
using the Recoil Distance Doppler-Shift technique applied to projectile Coulomb
excitation reactions. The deduced E2 strengths illustrate the enhanced
collectivity of the neutron-rich Fe isotopes up to N=40. The results are
interpreted by the generalized concept of valence proton symmetry which
describes the evolution of nuclear structure around N=40 as governed by the
number of valence protons with respect to Z~30. The deformation suggested by
the experimental data is reproduced by state-of-the-art shell calculations with
a new effective interaction developed for the fpgd valence space.Comment: 4 pages, 2 figure
Efficient Project Delivery Using Lean Principles - An Indian Case Study
Construction industry in India is growing at a rapid pace. Along with this growth, the industry is facing numerous challenges that are making delivery of projects inefficient. Experts believe that capacity constraints in the industry need to be addressed immediately. Government has recommended ‘introduction of efficient technologies and modern management techniques’ to increase the productivity of the industry. In this context, lean principles can act as a lever to make project delivery more efficient and provide the much needed impetus to the Indian construction sector. Around the globe lean principles are showing positive results on the projects. Project teams are reporting improvements in construction time, cost and quality along with softer benefits of enhanced collaboration, coordination and trust in project teams. Can adoption of lean principles provide similar benefits in the Indian construction sector? This research was conducted to answer this question. Using an action research approach a key lean construction tool called Last Planner System (LPS) was tested on a large Indian construction project. The work described in this work investigates the improvements achieved in project delivery by adopting LPS in Indian construction sector. Comparison in pre- and post-implementation data demonstrates increase in the certainty of work-flow and improves schedule compliance. This is measured through a simple LPS metric called percent plan complete. Explicit improvements in schedule performance are seen during 8 week LPS implementation along with implicit improvements in coordination, collaboration and trust in the project team. This work reports the findings of LPS implementation on the case study project outlining the barriers and drivers to adoption, strategies needed to ensure successful implementation and roadmap for implementation. Based on the findings the authors envision that lean construction can make project delivery more efficient in India
Excited-state transition-rate measurements in C-18
Excited states in C-18 were populated by the one-proton knockout reaction of an intermediate energy radioactive N-19 beam. The lifetime of the first 2(+) state was measured with the Koln/NSCL plunger via the recoil distance method to be tau (2(1)(+)) = 22.4 +/- 0.9(stat)(-2.2)(+3.3)(syst) ps, which corresponds to a reduced quadrupole transition strength of B(E2; 2(1)(+) -> 0(1)(+)) = 3.64(-0.14)(+ 0.15)(stat)(-0.47)(+0.40)(syst) e(2)fm(4). In addition, an upper limit on the lifetime of a higher-lying state feeding the 2(1)(+) state was measured to be tau < 4.6 ps. The results are compared to large-scale ab initio no-core shell model calculations using two accurate nucleon-nucleon interactions and the importance-truncation scheme. The comparison provides strong evidence that the inclusion of three-body forces is needed to describe the low-lying excited-state properties of this A = 18 system
- …