10,350 research outputs found
The central configurations of four masses x, -x, y, -y
The configuration of a homothetic motion in the N-body problem is called a
central configuration. In this paper, we prove that there are exactly three
planar non-collinear central configurations for masses x, -x, y, -y with x
different from y (a parallelogram and two trapezoids) and two planar
non-collinear central configurations for masses x, -x, x, -x (two diamonds).
Except the case studied here, the only known case where the four-body central
configurations with non-vanishing masses can be listed is the case with equal
masses (Albouy, 1996), which requires the use of a symbolic computation
program. Thanks to a lemma used in the proof of our result, we also show that a
co-circular four-body central configuration has non-vanishing total mass or
vanishing multiplier
Computational Results for Extensive-Form Adversarial Team Games
We provide, to the best of our knowledge, the first computational study of
extensive-form adversarial team games. These games are sequential, zero-sum
games in which a team of players, sharing the same utility function, faces an
adversary. We define three different scenarios according to the communication
capabilities of the team. In the first, the teammates can communicate and
correlate their actions both before and during the play. In the second, they
can only communicate before the play. In the third, no communication is
possible at all. We define the most suitable solution concepts, and we study
the inefficiency caused by partial or null communication, showing that the
inefficiency can be arbitrarily large in the size of the game tree.
Furthermore, we study the computational complexity of the equilibrium-finding
problem in the three scenarios mentioned above, and we provide, for each of the
three scenarios, an exact algorithm. Finally, we empirically evaluate the
scalability of the algorithms in random games and the inefficiency caused by
partial or null communication
On the potential of Cherenkov Telescope Arrays and KM3 Neutrino Telescopes for the detection of extended sources
We discuss the discovery potential of extended very-high-energy (VHE)
neutrino sources by the future KM3 Neutrino Telescope (KM3NeT) in the context
of the constraining power of the Cherenkov Telescope Array (CTA), designed for
deep surveys of the sky in VHE gamma rays. The study is based on a comparative
analysis of sensitivities of KM3NeT and CTA. We show that a minimum gamma-ray
energy flux of E^2{\phi}_{\gamma}(10 TeV) > 1x10^{-12} TeV cm^{-2} s^{-1} is
required to identify a possible neutrino counterpart with a 3{\sigma}
significance and 10 years of KM3NeT observations with upgoing muons, if the
source has an angular size of R_{src} = 0.1 deg and emits gamma rays with an
E^{-2} energy spectrum through a full hadronic mechanism. This minimum
gamma-ray flux is increased to the level of E^2{\phi}_{\gamma}(10 TeV) >
2x10^{-11} TeV cm^{-2} s^{-1} in case of sources with radial extension of
R_{src} = 2.0 deg. The analysis methods are applied to the supernova remnant RX
J1713.7-3946 and the Galactic Center Ridge, as well as to the recent HAWC
catalog of multi-TeV gamma-ray sources.Comment: 15 pages, 7 figure
Clinical and biochemical response to neridronate treatment in a patient with osteoporosis-pseudoglioma syndrome (OPPG)
Osteoporosis-pseudoglioma syndrome (OPPG) is a rare autosomal recessive syndrome characterized by juvenile-onset osteoporosis and ocular abnormalities due to a low-density lipoprotein receptor-related protein 5 (LRP5) gene mutation. Treatment with bisphosphonates, particularly with pamidronate and risedronate, has been reported to be of some efficacy in this condition. We report on a patient with OPPG due to an LRP5 gene mutation, who showed an encouraging response after a 36-month period of neridronate therapy. We report a case of a patient treated with bisphosphonates. Bisphosphonates should be administered in OPPG patients as a first-line therapy during early childhood
Serum creatine kinase isoenzymes in children with osteogenesis imperfecta
This study evaluates serum creatine kinase isoenzyme
activity in children with osteogenesis imperfecta to determine
its usefulness as a biochemical marker during treatment
with bisphosphonate. The changes of creatine kinase
(CK) isoenzyme activity during and after discontinuation therapy
were observed. These results could be useful in addressing
over-treatment risk prevention.
Introduction The brain isoenzyme of creatine kinase (CKbb)
is highly expressed in mature osteoclasts during osteoclastogenesis,
thus plays an important role in bone resorption. We
previously identified high serum CKbb levels in 18 children
with osteogenesis imperfect (OI) type 1 treated for 1 year with
bisphosphonate (neridronate). In the present study, serum CK
isoenzymes were evaluated in the same children with continuous
versus discontinued neridronate treatment over a further
2-year follow-up period.
Methods This study included 18 children with OI type 1, 12
with continued (group A) and 6 with ceased (group B)
neridronate treatment. Auxological data, serum biochemical
markers of bone metabolism, bone mineral density z-score,
and serum total CK and isoenzyme activities were determined
in both groups.
Results Serum CKbb was progressively and significantly increased
in group A (p < 0.004) but rapidly decreased to undetectable
levels in group B. In both groups, the cardiac muscle
creatine kinase isoenzyme (CKmb) showed a marked decrease,
while serum C-terminal telopeptide (CTx) levels were
almost unchanged.
Conclusions This study provides evidence of the cumulative
effect of neridronate administration in increasing serum CKbb
levels and the reversible effect after its discontinuation. This
approach could be employed for verifying the usefulness of
serum CKbb as a biochemical marker in patients receiving
prolonged bisphosphonate treatment. Moreover, the decreased
serum CKmb levels suggest a systemic effect of these drugs
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