2,528,252 research outputs found
A proof of the Riemann hypothesis based on the Koch theorem, on primes in short intervals, and distribution of nontrivial zeros of the Riemann zeta function
Part One: Let define the truncation of the logarithmic integral as First, we
prove which implies that the point of
the truncation depends on x, Next, let . We prove
that is greater than for and tends to
as . Thirdly, we prove Finally, we prove
Part Two: Let define where we proved that the pair of
numbers and in satisfy inequalities
, and the number is approximately a
step function of the variable with a finite amount of deviation, and
proportional to . We obtain much more accurate estimation
of prime numbers, the error range of which is less than
for or less than for
.
Part Three: We show the closeness of and and give the
difference being less than or equal to where
is a constant. Further more, we prove the estimation
. Hence we obtain so
that the Riemann hypothesis is true.
Part Four: Different from former researches on the distribution of primes in
short intervals, we prove a theorem: Let , ,
and which satisfies . Then there are and Comment: 95 page
A study of the kinetics of the oxidative coupling of methane over a Li/Sn/MgO catalyst
The rate of reaction of methane with oxygen in the presence of a Li/Sn/MgO catalyst has been studied as a function of the partial pressures of CH4, O2 and CO2 using a well-mixed reaction system which is practically gradientless with respect to gas-phase concentrations. It is concluded that the rate-determining step involves reaction of a molecule of CH4 adsorbed on the catalyst surface with an adsorbed di-atomic oxygen species. The kinetics are consistent with a Langmuir-Hinshelwood type mechanism involving competitive adsorption of CH4, O2 and CO2 on a single site. A comparison is made with previously published results for the Li/MgO material
On the lithium content of the globular cluster M92
I use literature data and a new temperature calibration to determine the Li
abundances in the globular cluster M 92. Based on the same data, Boesgaard et
al. have claimed that there is a dispersion in Li abundances in excess of
observational errors. This result has been brought as evidence for Li depletion
in metal-poor dwarfs. In the present note I argue that there is no strong
evidence for intrinsic dispersion in Li abundances, although a dispersion as
large as 0.18 dex is possible. The mean Li abundance, A(Li)=2.36, is in good
agreement with recent results for field stars and TO stars in the metal-poor
globular cluster NGC 6397. The simplest interpretation is that this constant
value represents the primordial Li abundance.Comment: A&A accepte
First-principles prediction of redox potentials in transition-metal compounds with LDA+U
First-principles calculations within the Local Density Approximation (LDA) or
Generalized Gradient Approximation (GGA), though very successful, are known to
underestimate redox potentials, such as those at which lithium intercalates in
transition metal compounds. We argue that this inaccuracy is related to the
lack of cancellation of electron self-interaction errors in LDA/GGA and can be
improved by using the DFT+ method with a self-consistent evaluation of the
parameter. We show that, using this approach, the experimental lithium
intercalation voltages of a number of transition metal compounds, including the
olivine LiMPO (M=Mn, Fe Co, Ni), layered LiMO (Co,
Ni) and spinel-like LiMO (M=Mn, Co), can be reproduced
accurately.Comment: 19 pages, 6 figures, Phys. Rev. B 70, 235121 (2004
Lithium distribution across the membrane of motoneurons in the isolated frog spinal cord
Lithium sensitive microelectrodes were used to investigate the transmembrane distribution of lithium ions (Li+) in motoneurons of the isolated frog spinal cord. After addition of 5 mmol·l–1 LiCl to the bathing solution the extracellular diffusion of Li+ was measured. At a depth of 500 m, about 60 min elapsed before the extracellular Li+ concentration approached that of the bathing solution. Intracellular measurements revealed that Li+ started to enter the cells soon after reaching the motoneuron pool and after up to 120 min superfusion, an intra — to extracellular concentration ratio of about 0.7 was obtained. The resting membrane potential and height of antidromically evoked action potentials were not altered by 5 mmol·l–1 Li+
The Median Largest Prime Factor
Let denote the median largest prime factor of the integers in the
interval . We prove that
where . From this, we obtain the asymptotic
where is the Euler Mascheroni constant. This answers a
question posed by Martin, and improves a result of Selfridge and Wunderlich.Comment: 7 page
Cerium: the lithium substitute in post-AGB stars
In this letter we present an alternative identification for the line detected
in the spectra of s-process enriched low-mass post-AGB stars around 6708A and
which was interpreted in the literature as due to Li. Newly released line lists
of lanthanide species reveal, however, the likely identification of the line to
be due to a CeII transition. We argue that this identification is consistent
with the Ce abundance of all the objects discussed in the literature and
conclude that in none of the low-mass s-process enriched post-AGB stars there
is indication for Li-production.Comment: 5 pages, 2 figures, accepted for publication as A&A Lette
Constraints to the Masses of Brown Dwarf Candidates from the Lithium Test
We present intermediate dispersion (0.7-2.2 \AA ~pix) optical
spectroscopic observations aimed at applying the ``Lithium Test'' to a sample
of ten brown dwarf candidates located in the general field, two in young open
clusters, and two in close binaries. We find evidence for strong Li depletion
in all of them, and thus infer lower mass limits of 0.065~M, depending
only slightly (0.005~M) on the interior models. None of the field
brown dwarf candidates in our sample appears to be a very young (age
~10~yr) substellar object. For one of the faintest proper motion
Pleiades members known (V=20.7) the Li test implies a mass greater than
0.08~M, and therefore it is not a brown dwarf. From our spectra
we estimate spectral types for some objects and present measurements of Halpha
emission strengths and radial velocities. Finally, we compare the positions in
the H-R diagram of our sample of brown dwarf candidates with the theoretical
region where Li is expected to be preserved (Substellar Lithium Region). We
find that certain combinations of temperature calibrations and evolutionary
tracks are consistent with the constraints imposed by the observed Li depletion
in brown dwarf candidates, while others are not.Comment: 20 pp.; 4 figs, available under request; plain LaTeX, ApJ in press,
OACatania-94-00
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