1,348 research outputs found
Time-resolved charge fractionalization in inhomogeneous Luttinger liquids
The recent observation of charge fractionalization in single
Tomanga-Luttinger liquids (TLLs) [Kamata et al., Nature Nanotech., 9 177
(2014)] opens new routes for a systematic investigation of this exotic quantum
phenomenon. In this Letter we perform measurements on two adjacent TLLs and put
forward an accurate theoretical framework to address the experiments. The
theory is based on the plasmon scattering approach and can deal with injected
charge pulses of arbitrary shape in TLL regions. We accurately reproduce and
interpret the time-resolved multiple fractionalization events in both single
and double TLLs. The effect of inter-correlations between the two TLLs is also
discussed.Comment: 5 pages + Supplementary Material. To appear in Phys. Rev. B: Rapid.
Com
A q-analog of the ADHMN construction and axisymmetric multi-instantons
In the preceding paper (Phys. Lett. B463 (1999) 257), the authors presented a
q-analog of the ADHMN construction and obtained a family of anti-selfdual
configurations with a parameter q for classical SU(2) Yang-Mills theory in
four-dimensional Euclidean space. The family of solutions can be seen as a
q-analog of the single BPS monopole preserving (anti-)selfduality. Further
discussion is made on the relation to axisymmetric ansatz on anti-selfdual
equation given by Witten in the late seventies. It is found that the
q-exponential functions familiar in q-analysis appear as analytic functions
categorizing the anti-selfdual configurations yielded by axisymmetric ansatz.Comment: 11pages, Latex2e, to appear in Journal of Physics A: Mathematical and
General as a `Special Issue/Difference Equations
Stable reduction of CCR5 by RNAi through hematopoietic stem cell transplant in non-human primates
RNAi is a powerful method for suppressing gene expression that has tremendous potential for therapeutic applications. However, because endogenous RNAi plays a role in normal cellular functions, delivery and expression of siRNAs must be balanced with safety. Here we report successful stable expression in primates of siRNAs directed to chemokine (c-c motif) receptor 5 (CCR5) introduced through CD34+ hematopoietic stem/progenitor cell transplant. After hematopoietic reconstitution, to date 14 months after transplant, we observe stably marked lymphocytes expressing siRNAs and consistent down-regulation of chemokine (c-c motif) receptor 5 expression. The marked cells are less susceptible to simian immunodeficiency virus infection ex vivo. These studies provide a successful demonstration that siRNAs can be used together with hematopoietic stem cell transplant to stably modulate gene expression in primates and potentially treat blood diseases such as HIV-1
Characterisation of the electromagnetic component in ultra-high energy inclined air showers
Inclined air showers - those arriving at ground with zenith angle with
respect to the vertical theta > 60 deg - are characterised by the dominance of
the muonic component at ground which is accompanied by an electromagnetic halo
produced mainly by muon decay and muon interactions. By means of Monte Carlo
simulations we give a full characterisation of the particle densities at ground
in ultra-high energy inclined showers as a function of primary energy and mass
composition, as well as for different hadronic models assumed in the
simulations. We also investigate the effect of intrinsic shower-to-shower
fluctuations in the particle densities.Comment: 31 pages, 18 figures, accepted for publication in Astroparticle
Physic
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A shared neural ensemble links distinct contextual memories encoded close in time.
Recent studies suggest that a shared neural ensemble may link distinct memories encoded close in time. According to the memory allocation hypothesis, learning triggers a temporary increase in neuronal excitability that biases the representation of a subsequent memory to the neuronal ensemble encoding the first memory, such that recall of one memory increases the likelihood of recalling the other memory. Here we show in mice that the overlap between the hippocampal CA1 ensembles activated by two distinct contexts acquired within a day is higher than when they are separated by a week. Several findings indicate that this overlap of neuronal ensembles links two contextual memories. First, fear paired with one context is transferred to a neutral context when the two contexts are acquired within a day but not across a week. Second, the first memory strengthens the second memory within a day but not across a week. Older mice, known to have lower CA1 excitability, do not show the overlap between ensembles, the transfer of fear between contexts, or the strengthening of the second memory. Finally, in aged mice, increasing cellular excitability and activating a common ensemble of CA1 neurons during two distinct context exposures rescued the deficit in linking memories. Taken together, these findings demonstrate that contextual memories encoded close in time are linked by directing storage into overlapping ensembles. Alteration of these processes by ageing could affect the temporal structure of memories, thus impairing efficient recall of related information
Quasi-periodic X-ray Flares from the Protostar YLW15
With ASCA, we have detected three X-ray flares from the Class I protostar
YLW15. The flares occurred every ~20 hours and showed an exponential decay with
time constant 30-60 ks. The X-ray spectra are explained by a thin thermal
plasma emission. The plasma temperature shows a fast-rise and slow-decay for
each flare with kT_{peak}~4-6 keV. The emission measure of the plasma shows
this time profile only for the first flare, and remains almost constant during
the second and third flares at the level of the tail of the first flare. The
peak flare luminosities L_{X,peak} were ~5-20 * 10^{31} erg s^{-1}, which are
among the brightest X-ray luminosities observed to date for Class I protostars.
The total energy released in each flare was 3-6*10^{36} ergs. The first flare
is well reproduced by the quasi-static cooling model, which is based on solar
flares, and it suggests that the plasma cools mainly radiatively, confined by a
semi-circular magnetic loop of length ~14 Ro with diameter-to-length ratio
\~0.07. The two subsequent flares were consistent with the reheating of the
same magnetic structure as of the first flare. The large-scale magnetic
structure and the periodicity of the flares imply that the reheating events of
the same magnetic loop originate in an interaction between the star and the
disk due to the differential rotation.Comment: Accepted by ApJ, 9 pages incl. 4 ps figure
Cohesion, team mental models, and collective efficacy: Towards an integrated framework of team dynamics in sport
A nomological network on team dynamics in sports consisting of a multi-framework perspective is introduced and tested. The aim was to explore the interrelationship among cohesion, team mental models (TMM), collective-efficacy (CE), and perceived performance potential (PPP). Three hundred and forty college-aged soccer players representing 17 different teams (8 female and 9 male) participated in the study. They responded to surveys on team cohesion, TMM, CE and PPP. Results are congruent with the theoretical conceptualization of a parsimonious view of team dynamics in sports. Specifically, cohesion was found to be an exogenous variable predicting both TMM and CE beliefs. TMM and CE were correlated and predicted PPP, which in turn accounted for 59% of the variance of objective performance scores as measured by teams’ season record. From a theoretical standpoint, findings resulted in a parsimonious view of team dynamics, which may represent an initial step towards clarifying the epistemological roots and nomological network of various team-level properties. From an applied standpoint, results suggest that team expertise starts with the establishment of team cohesion. Following the establishment of cohesiveness, teammates are able to advance team-related schemas and a collective sense of confidence. Limitations and key directions for future research are outlined
Nodal Structure of Unconventional Superconductors Probed by the Angle Resolved Thermal Transport Measurements
Over the past two decades, unconventional superconductivity with gap symmetry
other than s-wave has been found in several classes of materials, including
heavy fermion (HF), high-T_c, and organic superconductors. Unconventional
superconductivity is characterized by anisotropic superconducting gap
functions, which may have zeros (nodes) along certain directions in the
Brillouin zone. The nodal structure is closely related to the pairing
interaction, and it is widely believed that the presence of nodes is a
signature of magnetic or some other exotic, rather than conventional
phonon-mediated, pairing mechanism. Therefore experimental determination of the
gap function is of fundamental importance. However, the detailed gap structure,
especially the direction of the nodes, is an unresolved issue in most
unconventional superconductors. Recently it has been demonstrated that the
thermal conductivity and specific heat measurements under magnetic field
rotated relative to the crystal axes are a powerful method for determining the
shape of the gap and the nodal directions in the bulk. Here we review the
theoretical underpinnings of the method and the results for the nodal structure
of several unconventional superconductors, including borocarbide YNiBC,
heavy fermions UPdAl, CeCoIn, and PrOsSb, organic
superconductor, -(BEDT-TTF)Cu(NCS), and ruthenate
SrRuO, determined by angular variation of the thermal conductivity and
heat capacity.Comment: topical review, 55 pages, 35 figures. Figure quality has been reduced
for submission to cond-mat, higher quality figures available from the authors
or from the publishe
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