1,149 research outputs found
Hierarchy problem and fine-tuning in a decoupling approach to multiscale effective potentials
In many realizations of beyond the Standard Model theories, new massive
particles are introduced, leading to a multi-scale system with widely separated
energy scales. In this setting the effective potential, which takes into
account quantum corrections for the scalar sector, has to be supplemented with
a prescription to handle the hierarchy in mass scales. In this paper, we focus
on the so-called decoupling method, which freezes the effects of heavy
particles on the RG running of the light degrees of freedom at low energies.
For a two-scalar theory, we disentangle the effects of the high-energy degrees
of freedom on the shape of the potential and on the fine-tuning of the model
parameters. We find that, while the decoupling method leads to an acceptable
and convergent effective potential, the method does not solve the fine-tuning
problem that is inherent to the hierarchy problem of multi-scale theories. We
also consider two alternative implementations of the decoupling, which give
different results for the shape of the potential, but still lead to similar
conclusions on the amount of fine-tuning in the model.Comment: 19 pages, 7 figure
On the equivalence of different approaches for generating multisoliton solutions of the KPII equation
The unexpectedly rich structure of the multisoliton solutions of the KPII
equation has been explored by using different approaches, running from dressing
method to twisting transformations and to the tau-function formulation. All
these approaches proved to be useful in order to display different properties
of these solutions and their related Jost solutions. The aim of this paper is
to establish the explicit formulae relating all these approaches. In addition
some hidden invariance properties of these multisoliton solutions are
discussed
Homogenization of magnitudes of the ISC Bulletin
We implemented an automatic procedure to download the hypocentral data of the online Bulletin of the International Seismological Centre (ISC) in order to produce in near real-time a homogeneous catalogue of the Global and EuroMediterranean instrumental seismicity to be used for forecasting experiments and other statistical analyses. For the interval covered by the reviewed ISC Bulletin, we adopt the ISC locations and convert the surface wave magnitude (Ms) and short-period body-wave magnitude (mb) as computed by the ISC to moment magnitude (Mw), using empirical relations. We merge the so obtained proxies with real Mw provided by global and EuroMediterranean moment tensor catalogues. For the most recent time interval (about 2 yr) for which the reviewed ISC Bulletin is not available, we do the same but using the preferred (prime) location provided by the ISC Bulletin and converting to Mw the Ms and mb provided by some authoritative agencies. For computing magnitude conversion equations, we use curvilinear relations defined in a previous work and the chi-square regression method that accounts for the uncertainties of both x and y variables
TRANSPERITONEAL LAPAROSCOPIC ADRENALECTOMY IN CHILDREN: INITIAL EXPERIENCE
PURPOSE: The use of mini-invasive approach for adrenalectomy is poorly defined in pediatric
patients, although laparoscopic adrenalectomy is considered a standard procedure in adults. The
aim of our study is to describe the safety and feasibility of minimally invasive adrenalectomy in
children based on surgical skills and results.
MATERIALS AND METHODS: This is a retrospective study of four pediatric laparoscopic
adrenalectomies performed in our centre between 2009 and 2012. All patients underwent
transperitoneal lateral laparoscopic adrenalectomy two of which were right adrenalectomies and
two were left.
RESULTS: Four laparoscopic adrenalectomies were performed. Indications for surgery were
neuroblastoma in two patients, secernent adrenocortical tumor in one patient and adrenocortical
nodular hyperplasia in the last one. Patients had a mean age of 87 months (range 17-156) at
diagnosis and the average lesion size was 3.23 cm (range 0.7-6.4). All laparoscopic
adrenalectomies were successful, no conversions to open surgery were required and no post-
operative complications or deaths occurred. The average operating time was 105 minutes (range
80-130), blood loss during surgery was minimal and the mean post-operative hospital stay was
3.75 days (range 3-5). None of the patients showed signs of recurring disease at 15-months follow-
up.
CONCLUSIONS: Laparoscopic adrenalectomy is a safe, feasible and reproducible technique
offering numerous advantages including shortening of operating times and post-operative hospital
stays, as well as reduction of blood loss and complications. It also provides good visibility and easy
access to other organs
KP line solitons and Tamari lattices
The KP-II equation possesses a class of line soliton solutions which can be
qualitatively described via a tropical approximation as a chain of rooted
binary trees, except at "critical" events where a transition to a different
rooted binary tree takes place. We prove that these correspond to maximal
chains in Tamari lattices (which are poset structures on associahedra). We
further derive results that allow to compute details of the evolution,
including the critical events. Moreover, we present some insights into the
structure of the more general line soliton solutions. All this yields a
characterization of possible evolutions of line soliton patterns on a shallow
fluid surface (provided that the KP-II approximation applies).Comment: 49 pages, 36 figures, second version: section 4 expande
Noise-induced perturbations of dispersion-managed solitons
We study noise-induced perturbations of dispersion-managed solitons by
developing soliton perturbation theory for the dispersion-managed nonlinear
Schroedinger (DMNLS) equation, which governs the long-term behavior of optical
fiber transmission systems and certain kinds of femtosecond lasers. We show
that the eigenmodes and generalized eigenmodes of the linearized DMNLS equation
around traveling-wave solutions can be generated from the invariances of the
DMNLS equations, we quantify the perturbation-induced parameter changes of the
solution in terms of the eigenmodes and the adjoint eigenmodes, and we obtain
evolution equations for the solution parameters. We then apply these results to
guide importance-sampled Monte-Carlo simulations and reconstruct the
probability density functions of the solution parameters under the effect of
noise.Comment: 12 pages, 6 figure
Once-daily intrapleural urokinase treatment of complicated parapneumonic effusion in pediatric patients
In this paper, we describe our experience in the treatment of childhood empyema using urokinase. Patients' ages ranged from 2 to 12 years. Urokinase (dosage: 3,100 IU/kg/day) was diluted in normal saline to produce 1000 IU/ml (maximum dosage 100,000 IU in 100 ml of normal saline). After 2 hours, the clamped catheters were released and connected to water-seal suction at a negative pressure of 10 cm H2O. Pleural irrigations were continued once a day until thoracostomy tube output decreased to less than 10 ml/day (urokinase treatment mean duration: 11.5 days). The complete resolution of the chest effusion was assessed on chest ultrasound scan and radiographs. None of the patients experienced any side effects due to urokinase. It would now seem reasonable to advocate small chest tube thoracostomy and intrapleural urokinase as first-line treatment of pleural empyema in children, with surgery indicated as a secondaryintervention
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