8,038 research outputs found
Velocity, energy and helicity of vortex knots and unknots
In this paper we determine the velocity, the energy and estimate writhe and
twist helicity contributions of vortex filaments in the shape of torus knots
and unknots (toroidal and poloidal coils) in a perfect fluid. Calculations are
performed by numerical integration of the Biot-Savart law. Vortex complexity is
parametrized by the winding number , given by the ratio of the number of
meridian wraps to that of the longitudinal wraps. We find that for vortex
knots and toroidal coils move faster and carry more energy than a reference
vortex ring of same size and circulation, whereas for knots and poloidal
coils have approximately same speed and energy of the reference vortex ring.
Helicity is dominated by the writhe contribution. Finally, we confirm the
stabilizing effect of the Biot-Savart law for all knots and unknots tested,
that are found to be structurally stable over a distance of several diameters.
Our results also apply to quantized vortices in superfluid He.Comment: 17 pages, 8 figures, 2 table
Distributed storage and cloud computing: a test case
Since 2003 the computing farm hosted by the INFN Tier3 facility in Trieste supports the activities of many scientific communities. Hundreds of jobs from 45 different VOs, including those of the LHC experiments, are processed simultaneously. Given that normally the requirements of the different computational communities are not synchronized, the probability that at any given time the resources owned by one of the participants are not fully utilized is quite high. A balanced compensation should in principle allocate the free resources to other users, but there are limits to this mechanism. In fact, the Trieste site may not hold the amount of data needed to attract enough analysis jobs, and even in that case there could be a lack of bandwidth for their access. The Trieste ALICE and CMS computing groups, in collaboration with other Italian groups, aim to overcome the limitations of existing solutions using two approaches: sharing the data among all the participants taking full advantage of GARR-X wide area networks (10 GB/s) and integrating the resources dedicated to batch analysis with the ones reserved for dynamic interactive analysis, through modern solutions as cloud computing
Lie group analysis of a generalized Krichever-Novikov differential-difference equation
The symmetry algebra of the differential--difference equation
where , and are arbitrary analytic functions is shown to have the
dimension 1 \le \mbox{dim}L \le 5. When , and are specific second
order polynomials in (depending on 6 constants) this is the integrable
discretization of the Krichever--Novikov equation. We find 3 cases when the
arbitrary functions are not polynomials and the symmetry algebra satisfies
\mbox{dim}L=2. These cases are shown not to be integrable. The symmetry
algebras are used to reduce the equations to purely difference ones. The
symmetry group is also used to impose periodicity and thus to
reduce the differential--difference equation to a system of coupled
ordinary three points difference equations
Evaluation Techniques and Systems for Answer Set Programming: a Survey
Answer set programming (ASP) is a prominent knowledge representation and reasoning paradigm that found both industrial and scientific applications. The success of ASP is due to the combination of two factors: a rich modeling language and the availability of efficient ASP implementations. In this paper we trace the history of ASP systems, describing the key evaluation techniques and their implementation in actual tools
De novo 1q21.3q22 duplication revaluation in a “cold” complex neuropsychiatric case with syndromic intellectual disability
Syndromic intellectual disability often obtains a genetic diagnosis due to the combination of first and next generation sequencing techniques, although their interpretation may require revaluation over the years. Here we report on a composite neuropsychiatric case whose phenotype includes moderate intellectual disability, spastic paraparesis, movement disorder, and bipolar disorder, harboring a 1.802 Mb de novo 1q21.3q22 duplication. The role of this duplication has been reconsidered in the light of negativity of many other genetic exams, and of the possible pathogenic role of many genes included in this duplication, potentially configuring a contiguous gene-duplication syndrome
Historical evolution of the concept of anorexia nervosa and relationships with orthorexia nervosa, autism, and obsessive-compulsive spectrum
Eating disorders have been defined as "characterized by persistence disturbance of eating or eating-related behavior that results in the altered consumption or absorption of food and that significantly impairs health or psychosocial functioning". The psychopathology of eating disorders changed across time under the influence of environmental factors, determining the emergence of new phenotypes. Some of these conditions are still under investigation and are not clearly identified as independent diagnostic entities. In this review, the historic evolution of the eating disorder concept up to the recent Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition, has been evaluated. We also examined literature supporting the inclusion of new emergent eating behaviors within the eating disorder spectrum, and their relationship with anorexia, autism, and obsessive-compulsive disorder. In particular, we focused on what is known about the symptoms, epidemiology, assessment, and diagnostic boundaries of a new problematic eating pattern called orthorexia nervosa that could be accepted as a new psychological syndrome, as emphasized by an increasing number of scientific articles in the last few years
Hubungan Baik Dengan Orang Yang Signifikan Dan Kontribusinya Terhadap Kebahagiaan Remaja Indonesia
Budaya memainkan peran penting terhadap upaya orang dalam meraih kebahagiaan. Di budaya kolektif, kebahagiaan dikonstruksikan sebagai harmoni sosial. Dengan demikian,bagi individu yang besar di budaya kolektif hubungan baik dengan orang-orang yang signifikan, seperti di Indonesia, akan mempengaruhi kebahagiaannya. Penelitian ini memiliki tiga tujuan yaitu untuk mengidentifikasi faktor-faktor yang membuat individubahagia, orang-orang yang mendukung kebahagiaan individu, dan orang-orang yang kepada mereka individu akan berbagi kebahagiaan. Responden penelitian adalah411 orang mahasiswa dari berbagai universitas di Pekanbaru.. Hasil analisis data menunjukkan bahwa memiliki relasi positif (49,7%), mendapatkan apreasiasi (23,9%), menikmati waktu luang (22,4%), dan melakukan aktifitas religius (2,8%) merupakan faktor utama bagi kebahagiaan individu di dalam kehidupan sehari-hari. Orang-orang yang mendukung dan membuat individu merasa bahagia adalah keluarga (66,8%), teman-teman (20,6%), dan orang-orang spesial (12,3%). Sementara itu, individu berbagikebahagiaan pada sahabat (47,5%), keluarga (31,9%), and pacar (14,1%). Ketiga hasil ini memperkuat gagasan bahwa hubungan dengan orang-orang yang signifikan memiliki kontribusi penting bagi kebahagiaan individu, khususnya remaja
Is baryon number violated when electroweak strings intercommute?
We reexamine the self-helicity and the intercommutation of electroweak
strings. A plausible argument for baryon number conservation when electroweak
strings intercommute is presented. The connection between a segment of
electroweak strings and a sphaleron is also discussed.Comment: CALT-68-1948, 11 pages, 5 figures available upon request. Replaced
with revised version. (Request should be sent to [email protected]
Localized induction equation and pseudospherical surfaces
We describe a close connection between the localized induction equation
hierarchy of integrable evolution equations on space curves, and surfaces of
constant negative Gauss curvature.Comment: 21 pages, AMSTeX file. To appear in Journal of Physics A:
Mathematical and Genera
Evidence for the naphthalene cation in a region of the interstellar medium with anomalous microwave emission
We report high resolution spectroscopy of the moderately reddened (A=3)
early type star Cernis 52 located in a region of the Perseus molecular cloud
complex with anomalous microwave emission. In addition to the presence of the
most common diffuse interstellar bands (DIBs) we detect two new interstellar or
circumstellar bands coincident to within 0.01% in wavelength with the two
strongest bands of the naphthalene cation (CH) as measured in
gas-phase laboratory spectroscopy at low temperatures and find marginal
evidence for the third strongest band.
Assuming these features are caused by the naphthalene cation, from the
measured intensity and available oscillator strengths we find that 0.008 % of
the carbon in the cloud could be in the form of this molecule. We expect
hydrogen additions to cause hydronaphthalene cations to be abundant in the
cloud and to contribute via electric dipole radiation to the anomalous
microwave emission. The identification of new interstellar features consistent
with transitions of the simplest polycyclic aromatic hydrocarbon adds support
to the hypothesis that this type of molecules are the carriers of both diffuse
interstellar bands and anomalous microwave emission.Comment: Accepted for publication in The Astrophysical Journa
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