1,535 research outputs found
Convergent Analytic Solutions for Homoclinic Orbits in Reversible and Non-reversible Systems
In this paper, convergent, multi-infinite, series solutions are derived for
the homoclinic orbits of a canonical fourth-order ODE system, in both
reversible and non-reversible cases. This ODE includes traveling-wave
reductions of many important nonlinear PDEs or PDE systems, for which these
analytical solutions would correspond to regular or localized pulses of the
PDE. As such, the homoclinic solutions derived here are clearly topical, and
they are shown to match closely to earlier results obtained by homoclinic
numerical shooting. In addition, the results for the non-reversible case go
beyond those that have been typically considered in analyses conducted within
bifurcation-theoretic settings.
We also comment on generalizing the treatment here to parameter regimes where
solutions homoclinic to exponentially small periodic orbits are known to exist,
as well as another possible extension placing the solutions derived here within
the framework of a comprehensive categorization of ALL possible traveling-wave
solutions, both smooth and non-smooth, for our governing ODE.Comment: arXiv admin note: text overlap with arXiv:math-ph/060606
Post-Double Hopf Bifurcation Dynamics and Adaptive Synchronization of a Hyperchaotic System
In this paper a four-dimensional hyperchaotic system with only one
equilibrium is considered and its double Hopf bifurcations are investigated.
The general post-bifurcation and stability analysis are carried out using the
normal form of the system obtained via the method of multiple scales. The
dynamics of the orbits predicted through the normal form comprises possible
regimes of periodic solutions, two-period tori, and three-period tori in
parameter space.
Moreover, we show how the hyperchaotic synchronization of this system can be
realized via an adaptive control scheme. Numerical simulations are included to
show the effectiveness of the designed control
Investigation of perognathus as an experi- mental organism for research in space biology progress report, 1 apr. - 30 jun. 1965
Reproduction of mice in confinemen
Investigation of perognathus as an experimen- tal organism for research in space biology fourth quarterly progress report, 1 jul. - 30 sep. 1964
Perognathus investigated as experimental organism for space biology researc
Investigation of Perognathus as an experimental organism for research in space biology Progress report, 1 Jul. - 30 Sep. 1965
Histopathology of pocket mouse intestine mucous after irradiation - growth and development data on laboratory pocket mous
Towards a Typology of Corporate Responsibility in Different Governance Contexts
This paper develops a typology of different country governance contexts, in which we propose four broad categories of countries in Sub-Saharan Africa. Our analysis measures the most appropriate methods for helping to create a climate that is receptive to fostering corporate accountability. Our criteria are based on several different factors, none of which is determinative: the natural resources of the country; the country\u27s dependence on one commodity; the corruption level; the stability and accountability of the government; the state of civil society; and the existence of ongoing conflict. Examining these factors together results in measuring not just the country\u27s receptivity to change, but also the means for producing change. At one end of the spectrum, what we label Category 0 countries, are nations with economies and governments that are so poorly managed that there is little multinational investment - sometimes even in the context of lucrative investment opportunities. At the other end lie those countries with acceptable levels of good governance, more developed economies and markets, and with, consequently, a comparatively high level of both domestic and multinational corporate investment. We examine the appropriateness of strategies to apply external or internal pressure in different types of countries. Next, we discuss the affects of applying the proposed intervention strategies to the countries, addressing both short and long-term expected results. We find that in Category 0 countries, with extremely low levels of international investment, strategies should focus on improving governance and overall human welfare, which often could lead to welcoming international corporate investment. Other categories of countries, with greater - and often problematic - international corporate involvement, require different types of approaches
Towards a Typology of Corporate Responsibility in Different Governance Contexts
This paper develops a typology of different country governance contexts, in which we propose four broad categories of countries in Sub-Saharan Africa. Our analysis measures the most appropriate methods for helping to create a climate that is receptive to fostering corporate accountability. Our criteria are based on several different factors, none of which is determinative: the natural resources of the country; the country\u27s dependence on one commodity; the corruption level; the stability and accountability of the government; the state of civil society; and the existence of ongoing conflict. Examining these factors together results in measuring not just the country\u27s receptivity to change, but also the means for producing change. At one end of the spectrum, what we label Category 0 countries, are nations with economies and governments that are so poorly managed that there is little multinational investment - sometimes even in the context of lucrative investment opportunities. At the other end lie those countries with acceptable levels of good governance, more developed economies and markets, and with, consequently, a comparatively high level of both domestic and multinational corporate investment. We examine the appropriateness of strategies to apply external or internal pressure in different types of countries. Next, we discuss the affects of applying the proposed intervention strategies to the countries, addressing both short and long-term expected results. We find that in Category 0 countries, with extremely low levels of international investment, strategies should focus on improving governance and overall human welfare, which often could lead to welcoming international corporate investment. Other categories of countries, with greater - and often problematic - international corporate involvement, require different types of approaches
La pietra naturale nei beni culturali
Le pietre ornamentali ricoprono un ruolo fondamentale per quei beni culturali costituiti parzialmente o interamente in materiale lapideo. In un contesto come quello italiano, la conoscenza dei litotipi utilizzati in ciascun ambito regionale, sia per le produzioni artistiche di pregio che per l’edilizia corrente, riveste certamente una particolare importanza. Infatti, l’impiego della pietra ha da sempre connotato in maniera determinante il paesaggio urbano e rurale. Lo studio dei litotipi ornamentali, la loro caratterizzazione e la loro conservazione rivolge l’attenzione sui materiali posti in opera e rappresenta una branca delle Scienze Geologiche e delle Scienze applicate ai Beni Culturali. Tale ricerca, regolata e normata secondo standard nazionali e internazionali, permette di ampliare l’esperienza scientifica e culturale. I materiali lapidei, la cui scelta d’impiego fu ed è tutt’oggi tutt’altro che casuale, rappresentano parte della storia e ne rappresentano il patrimonio tangibil
A re-analysis of the NuSTAR and XMM-Newton broad-band spectrum of Ser~X-1
Context: Ser X-1 is a well studied LMXB which clearly shows a broad iron
line. Recently, Miller et al. (2103) have presented broad-band, high quality
NuSTAR data of SerX-1.Using relativistically smeared self-consistent reflection
models, they find a value of R_in close to 1.0 R_ISCO (corresponding to 6 R_g),
and a low inclination angle, less than 10 deg. Aims: The aim of this paper is
to probe to what extent the choice of reflection and continuum models (and
uncertainties therein) can affect the conclusions about the disk parameters
inferred from the reflection component. To this aim we re-analyze all the
available public NuSTAR and XMM-Newton. Ser X-1 is a well studied source, its
spectrum has been observed by several instruments, and is therefore one of the
best sources for this study. Methods: We use slightly different continuum and
reflection models with respect to those adopted in literature for this source.
In particular we fit the iron line and other reflection features with
self-consistent reflection models as reflionx (with a power-law illuminating
continuum modified with a high energy cutoff to mimic the shape of the incident
Comptonization spectrum) and rfxconv. With these models we fit NuSTAR and
XMM-Newton spectra yielding consistent spectral results. Results: Our results
are in line with those already found by Miller et al. (2013) but less extreme.
In particular, we find the inner disk radius at about 13 R_g and an inclination
angle with respect to the line of sight of about 27 deg. We conclude that,
while the choice of the reflection model has little impact on the disk
parameters, as soon as a self-consistent model is used, the choice of the
continuum model can be important in the precise determination of the disk
parameters from the reflection component. Hence broad-band X-ray spectra are
highly preferable to constrain the continuum and disk parameters.Comment: 13 pages including 8 figures. Accepted for publication in A&
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