2,458 research outputs found
A new kind of Lax-Oleinik type operator with parameters for time-periodic positive definite Lagrangian systems
In this paper we introduce a new kind of Lax-Oleinik type operator with
parameters associated with positive definite Lagrangian systems for both the
time-periodic case and the time-independent case. On one hand, the new family
of Lax-Oleinik type operators with an arbitrary as
initial condition converges to a backward weak KAM solution in the
time-periodic case, while it was shown by Fathi and Mather that there is no
such convergence of the Lax-Oleinik semigroup. On the other hand, the new
family of Lax-Oleinik type operators with an arbitrary
as initial condition converges to a backward weak KAM solution faster than the
Lax-Oleinik semigroup in the time-independent case.Comment: We give a new definition of Lax-Oleinik type operator; add some
reference
Weak KAM for commuting Hamiltonians
For two commuting Tonelli Hamiltonians, we recover the commutation of the
Lax-Oleinik semi-groups, a result of Barles and Tourin ([BT01]), using a direct
geometrical method (Stoke's theorem). We also obtain a "generalization" of a
theorem of Maderna ([Mad02]). More precisely, we prove that if the phase space
is the cotangent of a compact manifold then the weak KAM solutions (or
viscosity solutions of the critical stationary Hamilton-Jacobi equation) for G
and for H are the same. As a corrolary we obtain the equality of the Aubry
sets, of the Peierls barrier and of flat parts of Mather's functions.
This is also related to works of Sorrentino ([Sor09]) and Bernard ([Ber07b]).Comment: 23 pages, accepted for publication in NonLinearity (january 29th
2010). Minor corrections, fifth part added on Mather's function (or
effective Hamiltonian
Periodic orbits of period 3 in the disc
Let f be an orientation preserving homeomorphism of the disc D2 which
possesses a periodic point of period 3. Then either f is isotopic, relative the
periodic orbit, to a homeomorphism g which is conjugate to a rotation by 2 pi
/3 or 4 pi /3, or f has a periodic point of least period n for each n in N*.Comment: 7 page
The quality of life in boys with Duchenne muscular dystrophy
We conducted a study to evaluate the quality of life in boys with Duchenne muscular dystrophy aged 8–18 years, compared with that in matched healthy controls. A total of 85 boys with Duchenne muscular dystrophy aged 8–18 years and 136 age, sex and living place matched healthy controls were included in this study. Patients and one of their parents separately completed the 27-item Persian version of KIDSCREEN questionnaire (child and adolescent version and parent version). From the children's perspective, the quality of life in patients was found to be lower in two subclasses: “physical activities and health” (p < 0.001) and “friends” (p = 0.005). Parental estimation of their sick child's quality of life was significantly lower than children's own assessment in two subclasses: “physical activities and health” (p < 0.001) and “general mood and feelings” (p < 0.001). Our results indicate that boys with Duchenne muscular dystrophy have quite a satisfactory quality of life. A happier and more hopeful life can be promoted through increasing social support and improving the parental knowledge regarding their child's more positive life perspective. © 2016 Elsevier B.V
Patent foramen ovale and neurosurgery in sitting position: a systematic review
We have conducted a systematic review of air embolism complications of neurosurgery in the sitting position and patent foramen ovale (PFO) closure. It assesses the risk and benefit of PFO closure before neurosurgery in the sitting position. The databases Medline, Embase, and Cochrane Controlled Trial Register were systematically searched from inception to November 2007 for keywords in both topics separately. In total, 4806 patients were considered for neurosurgery in sitting position and 5416 patients underwent percutaneous PFO closure. The overall rate of venous air embolism during neurosurgery in sitting position was 39% for posterior fossa surgery and 12% for cervical surgery. The rate of clinical and transoesophageal echocardiography detected paradoxical air embolism was reported between 0% and 14%. The overall success rate for PFO closure using new and the most common closure devices was reported 99%, whereas the average risk of major complications is <1%. On the basis of our systematic review, we recommend screening for PFO and considering closure in cases in which the sitting position is the preferred neurosurgical approach. Our proposed management including the time of PFO closure according to available data is presented. However, the conclusions from our systematic review may be limited due to the lack of level A evidence and from using data from observational cohort studies. Thus, definite evidence-based recommendations require prospective evaluation of the issue in well-designed studie
MicroRNA-129-1 acts as tumour suppressor and induces cell cycle arrest of GBM cancer cells through targeting IGF2BP3 and MAPK1
Background MicroRNA-129-1 (miR-129-1) seems to behave as a tumour suppressor since its decreased expression is associated with different tumours such as glioblastoma multiforme (GBM). GBM is the most common form of brain tumours originating from glial cells. The impact of miR-129-1 downregulation on GBM pathogenesis has yet to be elucidated. Methods MiR-129-1 was overexpressed in GBM cells, and its effect on proliferation was investigated by cell cycle assay. MiR-129-1 predicted targets (CDK6, IGF1, HDAC2, IGF2BP3 and MAPK1) were also evaluated by western blot and luciferase assay. Results Restoration of miR-129-1 reduced cell proliferation and induced G1 accumulation, significantly. Several functional assays confirmed IGF2BP3, MAPK1 and CDK6 as targets of miR-129-1. Despite the fact that IGF1 expression can be suppressed by miR-129-1, through 30-untranslated region complementary sequence, we could not find any association between IGF1 expression and GBM. MiR-129-1 expression inversely correlates with CDK6, IGF2BP3 and MAPK1 in primary clinical samples. Conclusion This is the first study to propose miR129-1 as a negative regulator of IGF2BP3 and MAPK1 and also a cell cycle arrest inducer in GBM cells. Our data suggests miR-129-1 as a potential tumour suppressor and presents a rationale for the use of miR-129-1 as a novel strategy to improve treatment response in GBM
Topological Entropy of Braids on the Torus
A fast method is presented for computing the topological entropy of braids on
the torus. This work is motivated by the need to analyze large braids when
studying two-dimensional flows via the braiding of a large number of particle
trajectories. Our approach is a generalization of Moussafir's technique for
braids on the sphere. Previous methods for computing topological entropies
include the Bestvina--Handel train-track algorithm and matrix representations
of the braid group. However, the Bestvina--Handel algorithm quickly becomes
computationally intractable for large braid words, and matrix methods give only
lower bounds, which are often poor for large braids. Our method is
computationally fast and appears to give exponential convergence towards the
exact entropy. As an illustration we apply our approach to the braiding of both
periodic and aperiodic trajectories in the sine flow. The efficiency of the
method allows us to explore how much extra information about flow entropy is
encoded in the braid as the number of trajectories becomes large.Comment: 19 pages, 44 figures. SIAM journal styl
Weak Liouville-Arnold Theorems & Their Implications
This paper studies the existence of invariant smooth Lagrangian graphs for
Tonelli Hamiltonian systems with symmetries. In particular, we consider Tonelli
Hamiltonians with n independent but not necessarily involutive constants of
motion and obtain two theorems reminiscent of the Liouville-Arnold theorem.
Moreover, we also obtain results on the structure of the configuration spaces
of such systems that are reminiscent of results on the configuration space of
completely integrable Tonelli Hamiltonians.Comment: 24 pages, 1 figure; v2 corrects typo in online abstract; v3 includes
new title (was: A Weak Liouville-Arnold Theorem), re-arrangement of
introduction, re-numbering of main theorems; v4 updates the authors' email
and physical addresses, clarifies notation in section 4. Final versio
Streaming Motions Towards the Supermassive Black Hole in NGC 1097
We have used GMOS-IFU and high resolution HST-ACS observations to map, in
unprecedented detail, the gas velocity field and structure within the 0.7 kpc
circumnuclear ring of the SBb LINER/Seyfert 1 galaxy NGC 1097. We find clear
evidence of radial streaming motions associated with spiral structures leading
to the unresolved (<3.5 parsecs) nucleus, which we interpret as part of the
fueling chain by which gas is transported to the nuclear starburst and
supermassive black hole.Comment: 4 pages, 3 figures using emulateapj. Accepted for publication in
Astrophysical Journal Letters. Download high-resolution version from
http://www.astro.uu.se/~kambiz/DOC/paper-N1097.pd
Perancangan Sistem Rain Water Harvesting, Studi Kasus: Hotel Novotel YOGYAKARTA
Perhatian pada sektor air bersih semakin meningkat secara signifikan. Pada World Summit on Sustainable Development (WSSD) di Johanesburg, 2-4 September 2002, air bersih menjadi salah satu perhatian dari lima sektor yang dibahas, yaitu water, energy, health, agriculture, dan biodiversity (disingkat sebagai WEHAB). Air bersih memiliki tingkat kepentingan yang tinggi dalam perkembangan aspek ekonomi, sosial, dan lingkungan. Banyak upaya dilakukan untuk menjaga pasokan air, termasuk penghematan air, waste water management, dan rain water harvesting (RWH). Pada penelitian ini, dilakukan analisis terhadap perancangan sistem RWH pada bangunan publik dengan studi kasus Hotel Novotel Yogyakarta. Kegiatan utamanya yaitu melakukan studi kelayakan pada existing building condition dan menganalisis potensi penghematan dengan pemanfaatan sistem RWH.Air hujan yang biasanya langsung dibuang ke saluran drainase kota dikumpulkan, kemudian diberikan pengolahan agar sesuai dengan standar kualitas air minum yang dikembangkan oleh World Health Organization (WHO) sehingga dapat dimanfaatkan sebagai sumber air bersih pada hotel. Selain itu, perancangan sistem RWH ini juga mengacu pada Greenship Rating Tools yang dikeluarkan oleh GBCI (Green Building Council Indonesia). Dari perhitungan yang dilakukan, rata-rata air hujan yang dapat ditampung dalam satu bulan yaitu 478.820 liter dan dalam satu tahun dapat terkumpul sebesar 5.745.809 liter. Pada musim hujan, air hujan pada Hotel Novotel dapat memasok hingga 21% dari total kebutuhan air bersih dalam satu bulan. Rata-rata konsumsi air yang dapat ditangani oleh air hujan dalam setahun adalah 8,6%
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