2,447 research outputs found
Unusual interplay between copper-spin and vortex dynamics in slightly overdoped La{1.83}Sr{0.17}CuO{4}
Our inelastic neutron scattering experiments of the spin excitations in the
slightly overdoped La{1.83}Sr{0.17}CuO{4} compound show that, under the
application of a magnetic field of 5 Tesla, the low-temperature susceptibility
undergoes a weight redistribution centered at the spin-gap energy. Furthermore,
by comparing the temperature dependence of the neutron data with
ac-susceptibility and magnetization measurements, we conclude that the filling
in of the spin gap tracks the irreversibility/melting temperature rather than
Tc2, which indicates an unusual interplay between the magnetic vortices and the
spin excitations even in the slightly overdoped regime of high-temperature
superconductors.Comment: 7 pages, including 5 figure
Strong Magnetization Measured in the Cool Cores of Galaxy Clusters
Tangential discontinuities, seen as X-ray edges known as cold fronts (CFs),
are ubiquitous in cool-core galaxy clusters. We analyze all 17 deprojected CF
thermal profiles found in the literature, including three new CFs we
tentatively identify (in clusters A2204 and 2A0335). We discover small but
significant thermal pressure drops below all nonmerger CFs, and argue that they
arise from strong magnetic fields below and parallel to the discontinuity,
carrying 10%-20% of the pressure. Such magnetization can stabilize the CFs, and
explain the CF-radio minihalo connection.Comment: PRL accepted, additional control tests adde
Ni-impurity effects on the superconducting gap of LaSrCuO studied from the magnetic field and temperature dependence of the electronic specific heat
The magnetic field and temperature dependence of the electronic specific heat
have been systematically investigated in (LSCNO) in order to study Ni-impurity
effects on the superconducting (SC) gap. In LSCNO with =0.15 and =0.015,
the value of () at =0 K, , is
enhanced under the magnetic field applied along the -axis. The
increment of , , follows the Volovik relation
=, characteristic of the SC gap with line nodes,
with prefactor similar to that of a pure sample. The vs.
curve under =0 shows a d-wave-like SC anomaly with an abrupt increase at
and -linear dependence at , although the
-value in the vs. curve increases with increasing
Ni concentrations. Interestingly, as the SC part of , , decreases in LSCNO, is
reduced in proportion to the decrease of . These findings can
be explained phenomenologically by a simple model in which Ni impurities bring
about strong pair breaking at the edges of the coherent nodal part of the Fermi
surface but in the vicinity of the nodes of the SC gap. The reduction of the SC
condensation energy in LSCNO, evaluated from at
{0.3em}\raisebox{0.4ex}{} {-0.75em}\raisebox{-.7ex}{} {0.3em}, is also understood by the same model.Comment: 7 pages, 6 figures, accepted in Phys. Rev.
STM/STS Study on 4a X 4a Electronic Charge Order and Inhomogeneous Pairing Gap in Superconducting Bi2Sr2CaCu2O8+d
We performed STM/STS measurements on underdoped Bi2212 crystals with doping
levels p ~ 0.11, ~ 0.13 and ~ 0.14 to examine the nature of the nondispersive
4a X 4a charge order in the superconducting state at T << Tc. The charge order
appears conspicuously within the pairing gap, and low doping tends to favor the
charge order. We point out the possibility that the 4a X 4a charge order will
be dynamical in itself, and pinned down over regions with effective pinning
centers. The pinned 4a X 4a charge order is closely related to the spatially
inhomogeneous pairing gap structure, which has often been reported in STS
measurements on high-Tc cuprates.Comment: 12 pages, 16 figures, to be published in Phys. Rev.
Lambda-prophage induction modeled as a cooperative failure mode of lytic repression
We analyze a system-level model for lytic repression of lambda-phage in E.
coli using reliability theory, showing that the repressor circuit comprises 4
redundant components whose failure mode is prophage induction. Our model
reflects the specific biochemical mechanisms involved in regulation, including
long-range cooperative binding, and its detailed predictions for prophage
induction in E. coli under ultra-violet radiation are in good agreement with
experimental data.Comment: added referenc
Dynamics of neural cryptography
Synchronization of neural networks has been used for novel public channel
protocols in cryptography. In the case of tree parity machines the dynamics of
both bidirectional synchronization and unidirectional learning is driven by
attractive and repulsive stochastic forces. Thus it can be described well by a
random walk model for the overlap between participating neural networks. For
that purpose transition probabilities and scaling laws for the step sizes are
derived analytically. Both these calculations as well as numerical simulations
show that bidirectional interaction leads to full synchronization on average.
In contrast, successful learning is only possible by means of fluctuations.
Consequently, synchronization is much faster than learning, which is essential
for the security of the neural key-exchange protocol. However, this qualitative
difference between bidirectional and unidirectional interaction vanishes if
tree parity machines with more than three hidden units are used, so that those
neural networks are not suitable for neural cryptography. In addition, the
effective number of keys which can be generated by the neural key-exchange
protocol is calculated using the entropy of the weight distribution. As this
quantity increases exponentially with the system size, brute-force attacks on
neural cryptography can easily be made unfeasible.Comment: 9 pages, 15 figures; typos correcte
Perancangan Buku Visual Tentang Tempe Sebagai Salah Satu Makanan Masyarakat Indonesia
Perancangan buku ini lebih mengajak masyarakat untuk mengenal lebih jauh tentang segala hal yang berhubungan dengan Tempe baik dari sejarah atau asal-usul, proses pembuatan, bahkan perkembangan Tempe sendiri di negara lain, dimana ternyata Tempe ini memiliki kelebihan dan manfaat positif yang jarang diketahui masyarakat selama ini, mengingat anggapan masyarakat terhadapTempedi masa dewasa ini lebih cenderung mengarah ke hal yang negatif. Padahal Tempe sendiri diyakini merupakan salah satu makanan masyarakatIndonesia. Perancangan buku ini didesain dengan elemen gambar foto secara dokumentatif dan artistik dengan perpaduan tata letak yang memudahkan untuk dibaca
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