2,565 research outputs found
A 3-D Track-Finding Processor for the CMS Level-1 Muon Trigger
We report on the design and test results of a prototype processor for the CMS
Level-1 trigger that performs 3-D track reconstruction and measurement from
data recorded by the cathode strip chambers of the endcap muon system. The
tracking algorithms are written in C++ using a class library we developed that
facilitates automatic conversion to Verilog. The code is synthesized into
firmware for field-programmable gate-arrays from the Xilinx Virtex-II series. A
second-generation prototype has been developed and is currently under test. It
performs regional track-finding in a 60 degree azimuthal sector and accepts 3
GB/s of input data synchronously with the 40 MHz beam crossing frequency. The
latency of the track-finding algorithms is expected to be 250 ns, including
geometrical alignment correction of incoming track segments and a final
momentum assignment based on the muon trajectory in the non-uniform magnetic
field in the CMS endcaps.Comment: 7 pages, 5 figures, proceedings for the conference on Computing in
High Energy and Nuclear Physics, March 24-28 2003, La Jolla, Californi
General principles of uncomplicated cystitis therapy during pregnancy
Urinary tract infections during pregnancy are associated with severe complications. Earlier initiation of antibiotic treatment for acute uncomplicated cystitis, reduces the various complications.Objective. To assess the effectiveness of fosfomycin in the treatment of acute uncomplicated cystitis during II and III trimester of pregnancy.Material and methods. The study included 74 pregnant women who had acute uncomplicated cystitis in II or III trimesters. All patients received fosfomycin trometamol 3.754 g (equivalent to 3 g fosfomycin) as antimicrobial therapy for acute uncomplicated cystitis. The drug was prescribed to 24 pregnant women in the II, and 50 in the III trimester of pregnancy.Results. After treatment with fosfomycin signs of acute cystitis gone in all patients. At the same time, regression of clinical symptoms was noted during the next days after therapy in 95.9% (n = 71) of cases. Repeated microbiological test of the middle portion of urine was performed 7 days after the end of antibiotic therapy. In 94.6% (n = 70) cases, total elimination of the pathogen was achieved. In 5.4% (n = 4) cases, there was a significant decrease of colonization Follow-up for three months showed the absence of recurrence of acute cystitis in all pregnant women who were included in the study.Conclusion. Fosfomycin is a highly effective drug in the treatment of uncomplicated cystitis during pregnancy
The effects of matter density uncertainties on neutrino oscillations in the Earth
We compare three different methods to evaluate uncertainties in the Earth's
matter density profile, which are relevant to long baseline experiments, such
as neutrino factories.Comment: 3 pages, 1 figure. Talk given at the NuFact'02 Workshop, London, 1-6
July, 200
Complex zeros of real ergodic eigenfunctions
We determine the limit distribution (as ) of complex
zeros for holomorphic continuations \phi_{\lambda}^{\C} to Grauert tubes of
real eigenfunctions of the Laplacian on a real analytic compact Riemannian
manifold with ergodic geodesic flow. If is an
ergodic sequence of eigenfunctions, we prove the weak limit formula
\frac{1}{\lambda_j} [Z_{\phi_{j_k}^{\C}}] \to \frac{i}{\pi} \bar{\partial}
{\partial} |\xi|_g, where [Z_{\phi_{j_k}^{\C}}] is the current of
integration over the complex zeros and where is with respect
to the adapted complex structure of Lempert-Sz\"oke and Guillemin-Stenzel.Comment: Added some examples and references. Also added a new Corollary, and
corrected some typo
Coexistence of antiferromagnetic order and unconventional superconductivity in heavy fermion compounds CeRh_{1-x}Ir_xIn_5: nuclear quadrupole resonance studies
We present a systematic ^{115}In NQR study on the heavy fermion compounds
CeRh_{1-x}Ir_xIn_5 (x=0.25, 0.35, 0.45, 0.5, 0.55 and 0.75). The results
provide strong evidence for the microscopic coexistence of antiferromagnetic
(AF) order and superconductivity (SC) in the range of 0.35 \leq x \leq 0.55.
Specifically, for x=0.5, T_N is observed at 3 K with a subsequent onset of
superconductivity at T_c=0.9 K. T_c reaches a maximum (0.94 K) at x=0.45 where
T_N is found to be the highest (4.0 K). Detailed analysis of the measured
spectra indicate that the same electrons participate in both SC and AF order.
The nuclear spin-lattice relaxation rate 1/T_1 shows a broad peak at T_N and
follows a T^3 variation below T_c, the latter property indicating
unconventional SC as in CeIrIn_5 (T_c=0.4 K). We further find that, in the
coexistence region, the T^3 dependence of 1/T_1 is replaced by a T-linear
variation below T\sim 0.4 K, with the value \frac{(T_1)_{T_c}}{(T_1)_{low-T}}
increasing with decreasing x, likely due to low-lying magnetic excitations
associated with the coexisting magnetism.Comment: 20 pages, 14 figure
Scale Dependent Dimension of Luminous Matter in the Universe
We present a geometrical model of the distribution of luminous matter in the
universe, derived from a very simple reaction-diffusion model of turbulent
phenomena. The apparent dimension of luminous matter, , depends linearly
on the logarithm of the scale under which the universe is viewed: , where is a correlation length.
Comparison with data from the SARS red-shift catalogue, and the LEDA database
provides a good fit with a correlation length Mpc. The
geometrical interpretation is clear: At small distances, the universe is
zero-dimensional and point-like. At distances of the order of 1 Mpc the
dimension is unity, indicating a filamentary, string-like structure; when
viewed at larger scales it gradually becomes 2-dimensional wall-like, and
finally, at and beyond the correlation length, it becomes uniform.Comment: 6 pages, 2 figure
Optimizing end-labeled free-solution electrophoresis by increasing the hydrodynamic friction of the drag-tag
We study the electrophoretic separation of polyelectrolytes of varying
lengths by means of end-labeled free-solution electrophoresis (ELFSE). A
coarse-grained molecular dynamics simulation model, using full electrostatic
interactions and a mesoscopic Lattice Boltzmann fluid to account for
hydrodynamic interactions, is used to characterize the drag coefficients of
different label types: linear and branched polymeric labels, as well as
transiently bound micelles.
It is specifically shown that the label's drag coefficient is determined by
its hydrodynamic size, and that the drag per label monomer is largest for
linear labels. However, the addition of side chains to a linear label offers
the possibility to increase the hydrodynamic size, and therefore the label
efficiency, without having to increase the linear length of the label, thereby
simplifying synthesis. The third class of labels investigated, transiently
bound micelles, seems very promising for the usage in ELFSE, as they provide a
significant higher hydrodynamic drag than the other label types.
The results are compared to theoretical predictions, and we investigate how
the efficiency of the ELFSE method can be improved by using smartly designed
drag-tags.Comment: 32 pages, 11 figures, submitted to Macromolecule
Appearance of Flat Bands and Edge States in Boron-Carbon-Nitride Nanoribbons
Presence of flat bands and edge states at the Fermi level in graphene
nanoribbons with zigzag edges is one of the most interesting and attracting
properties of nanocarbon materials but it is believed that they are quite
fragile states and disappear when B and N atoms are doped at around the edges.
In this paper, we theoretically investigate electronic and magnetic properties
of boron-carbon-nitride (BCN) nanoribbons with zigzag edges where the outermost
C atoms on the edges are alternately replaced with B and N atoms using the
first principles calculations. We show that BCN nanoribbons have the flat bands
and edge states at the Fermi level in both H_2 rich and poor environments. The
flat bands are similar to those at graphene nanoribbons with zigzag edges, but
the distributions of charge and spin densities are different between them. A
tight binding model and the Hubbard model analysis show that the difference in
the distribution of charge and spin densities is caused by the different site
energies of B and N atoms compared with C atoms.Comment: 5 pages; 3 figure
Electronic and Magnetic Properties of Partially-Open Carbon Nanotubes
On the basis of the spin-polarized density functional theory calculations, we
demonstrate that partially-open carbon nanotubes (CNTs) observed in recent
experiments have rich electronic and magnetic properties which depend on the
degree of the opening. A partially-open armchair CNT is converted from a metal
to a semiconductor, and then to a spin-polarized semiconductor by increasing
the length of the opening on the wall. Spin-polarized states become
increasingly more stable than nonmagnetic states as the length of the opening
is further increased. In addition, external electric fields or chemical
modifications are usable to control the electronic and magnetic properties of
the system. We show that half-metallicity may be achieved and the spin current
may be controlled by external electric fields or by asymmetric
functionalization of the edges of the opening. Our findings suggest that
partially-open CNTs may offer unique opportunities for the future development
of nanoscale electronics and spintronics.Comment: 6 figures, to appear in J. Am. Chem. So
"Narrow" Graphene Nanoribbons Made Easier by Partial Hydrogenation
It is a challenge to synthesize graphene nanoribbons (GNRs) with narrow
widths and smooth edges in large scale. Our first principles study on the
hydrogenation of GNRs shows that the hydrogenation starts from the edges of
GNRs and proceeds gradually toward the middle of the GNRs so as to maximize the
number of carbon-carbon - bonds. Furthermore, the partially
hydrogenated wide GNRs have similar electronic and magnetic properties as those
of narrow GNRs. Therefore, it is not necessary to directly produce narrow GNRs
for realistic applications because partial hydrogenation could make wide GNRs
"narrower"
- …