Pattern formation

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Pattern formation in clonal plants

Pattern formation in clonal plants

In Sec. 1.2 we describe how we derived the equation and the assumptions we took. In Sec. 2.1 we perform the linear stability analysis of the homogeneous system showing that it reproduces the basic bifurcation diagram (transcritical bifurcation and saddle node) of the numerical model, then we expand the analysis introducing the spacial derivatives in Sec. 2.2 thus determining the modulation instability points. Such study lead us to the conclusion that an additional factor was missing to the original formulation, as exposed in Sec. 2.2.3. Thus in Sec. 2.3 we repeat the analysis including the new term and see that the equation reproduces exactly the dynamical results of the ABD model. Starting from Sec. 3 we perform numerical validations, firstly we show that the terms we inserted reproduce the expected features (Sec. 3.1) then we verify that the regions of pattern formation are in accordance with the analytical results (Sec. 3.2 ). Finally we use the model to show the potentiality in designing effective re-population strategies for seagrasses (Sec. 4).
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33 Lee mas

Vegetation pattern formation in a fog dependent ecosystem

Vegetation pattern formation in a fog dependent ecosystem

The study of pattern formation may provide a way to better understand and create early warning systems (see Scheffer et al., 2009) for the impacts of global environmental change, one of the major challenges ahead of us. Along this line, ecosystems modeling has allowed considerable advances generating strong predictions about the behavior of real ecosystems under extreme conditions. For example, the desertification phenomenon (an abrupt shift to a desert state), which is irreversible and manly attributed to a decrease in rainfall (Rietkerk et al., 2004), can also occur due to changes in external conditions that reduce resilience without affecting the equilibrium state of the system, which appears unaltered until it suddenly shifts to a more degraded state (Scheffer et al., 2001; Scheffer and Carpenter, 2003). Several authors have emphasized that the shape of the vegetation pattern should be taken as an early warning signal of the fact that ecosystems may suddenly undergo irreversible shifts (Rietkerk et al., 2004; Kefi et al., 2008; Ursino, 2009). This is specially important if it is considered that arid and semi-arid ecosystems are among the most sensitive to climate change (Kefi et al., 2008). In summary, we show in this study, for the first time, that the formation of banded vegetation patterns can develop under advective water inputs as in the fog-dependent ecosystems in the Atacama Desert. Further, we show that the mechanisms, based on scale-dependent feedbacks, are common to a variety of arid runoff-dependent ecosystems. We also show that the
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9 Lee mas

Travelling waves in a nonlinear degenerate diffusion model for bacterial pattern formation

Travelling waves in a nonlinear degenerate diffusion model for bacterial pattern formation

Bacterial colonies grown on the surface of thin agar plates can develop various types of spatial patterns including rings, spots, disks and patterns with a dense- branching morphology (DBM). The nature of the pattern exhibited depends on the particular bacterial species used and the environmental conditions imposed. The spatio-temporal patterns generated by the bacterium Bacillus subtilis were investigated in Kawasaki et al. [5] using a reaction diffusion type model, and the authors presented the first demonstration of branching pattern formation of bacte- rial colonies in the framework of a reaction diffusion system. Closer investigation of these patterns revealed that, although the colony grows on the two-dimensional surface of the agar plate, each tip elongates in one dimension apart from occasion- ally branching. The authors therefore considered a one-dimensional version of their model and showed, using numerical simulations, that the model exhibited travelling wave solutions with a constant speed that closely approximated the speed of the solution profile to the full two-dimensional problem.
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24 Lee mas

1 LOCALIZED STRUCTURES AND PATTERN FORMATION IN ACOUSTIC RESONATOR CONTAINING VISCOUS FLUID

1 LOCALIZED STRUCTURES AND PATTERN FORMATION IN ACOUSTIC RESONATOR CONTAINING VISCOUS FLUID

We report on a new type of localized structure, an ultrasonic cavity soliton, supported by large aspect-ratio acoustic resonators containing viscous media. These states of the acoustic and thermal fields are robust structures, existing whenever a spatially uniform solution and a periodic pattern coexist. We derive the equations which describe the system including spatial effects. The spatio-temporal dynamics of the system is analyzed from the microscopic model, and the results are in good agreement with the numerical results, such as with previous experimental works.
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7 Lee mas

Pattern formation of parametrically driven surface waves induced by vibration

Pattern formation of parametrically driven surface waves induced by vibration

The goal of chapter 2 is to obtain the above mentioned general ampli- tude equation and the boundary appropriate conditions that apply to the amplitude equation. These are the foundations of the theoretical analysis that is developed in the thesis and and will be used, in particular, to analyze the subharmonic surfaces waves that are driven by horizontal vibration in a rectangular container. The usual approach in rectangular containers is to decompose the patterns into plane waves whose amplitudes evolve slowly according to an associated set of amplitude equations. Here, instead, a new approach is undertaken in which no particular pattern is assumed. Specifi- cally, a purely two-dimensional, linear evolution equation for the free surface elevation is derived that has substantial interest in itself. It is a general amplitude equation since it is independent of the container geometry and allows for any possible spatially modulated pattern composed by waves in arbitrary orientations. Similar equations have been derived by phenomeno- logical arguments for Faraday waves (Zhang & Viñals 1995). The boundary conditions account for wave reflection at the sidewalls and endwalls, and they are derived using the Fourier transform of the local solution in a region near the container walls. A linear stability analysis using normal mode ex- pansions is applied to obtain the neutral stability curves. The minima of these curves select the critical amplitude and the orientation of the patterns. Weak mode interaction is also considered to study the secondary bifurca- tion. Then, the effect of varying the different non-dimensional parameters of the problem is studied. The model is validated with the experimental made by Porter et al. (2012).
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145 Lee mas

Nonequilibrium Statistical Physics in Ecology: Vegetation Patterns, Animal Mobility and Temporal Fluctuations

Nonequilibrium Statistical Physics in Ecology: Vegetation Patterns, Animal Mobility and Temporal Fluctuations

kernels are more peaked around x = 0 for p < 2 and more box-like when p > 2. It turns out that this family of functions has non-negative Fourier transform for 0 ≤ p < 2, so that no patterns appear in this case. A lengthy discussion of this property in the context of competition of species can be found in Pigolotti et al. [2007]. Thus, the shape of the competition kernel dictates whether or not patterns will appear in the system. If pattern formation is possible, then the values of the fire and competition parameters govern the type of solution (see Sec. 2.2.3). Our central result for nonlocal competition is that, contrary to conventional wisdom, it can, in the limit of infinitesimally short (purely local) facilitation, promote the clustering of trees. Whether or not this occurs depends entirely on the shape of the competition kernel. For large p we have a box-like shape, and in these cases trees compete strongly with other trees, roughly within a distance R from their position. The mechanism behind this counterintuitive result is that trees farther than R away from a resident tree area are not able to invade the zone defined by the radius R around the established tree (their seeds do not establish there), so that an exclusion zone develops around it. For smaller p there is less competition and the exclusion zones disappear. We will develop longer this concept in the next chapter.
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174 Lee mas

Pattern Definitions and Semantically Annotated Instances

Pattern Definitions and Semantically Annotated Instances

Regarding the expressiveness of the pattern definition language, it currently allows roles, concepts and individuals to be treated as parameters. This may be sufficient in most cases, but it might be interesting to have other parametrisable parts of an ontology. For instance, numbers in cardinality restrictions could also be parameters. Note that the introduction of parametricity at this level would likely make the pattern definition no longer be an ontology.

8 Lee mas

The distributed nature of pattern generalization

The distributed nature of pattern generalization

Radford notes that the entry into, and presence of, variable-based generaliza- tions do not necessarily convey meaningful algebraic generalizations. This claim underscores his much larger view in which the presence and use of letters do not necessarily “amount to doing algebra,” that “just as not all symbolization is alge- braic, not all patterning activity leads to algebraic thinking” (Radford, 2006, p. 3). There are students, for example, who produce symbolic generalizations on the basis of some “procedural mechanism” following a “trial-and-error” heuristic that they are sometimes unable to explain beyond the response “Uh… because it works!” on the basis of a number of additional extensional generalizations (Rad- ford, 2000, p. 82). Radford (2006) categorizes this process as naïve induction. Also, there are those who produce recursively additive formulas (in the form Next = Current + Common Difference, which Radford (2006) classifies as arith- metical generalizations), however, they are unable to use them correctly when confronted with a far generalization task. Even in situations when some students are able to verbalize regularities and talk about the general through the particular, in some cases their underlying understanding of the pattern under investigation appears to remain at either the iconical or indexical level in which case they fail to establish equivalent structures. Suffice it to say, PGs that yield symbolic vari- able-based generalizations depend significantly on the context in which individu- al learners understand variables and, more generally, sign use.
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27 Lee mas

A Security Pattern for Cloud service certification

A Security Pattern for Cloud service certification

As it was previously pointed out, this paper presents an approach built on a combination of software certification and hardware based certification techniques [Muñoz and Maña 2014]. The cornerstone in our model is Trusted Computing technology, we take advantage of its functionalities as secure element. TPM becomes the anchor of our certification chain. Consequently, bringing the gap existing between the software certification and the means for hardware certification becomes as a target. Since the secure systems based on Trusted Computing tends to be hard to implement in real scenarios, we present a security pattern [Gallego-Nicasio et al. ; Schumacher et al. 2005].
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8 Lee mas

Pattern-based OWL Ontology Debugging Guidelines

Pattern-based OWL Ontology Debugging Guidelines

- Guidelines (G). They represent complex expressions used in an ontology component denition that are correct from the logical and cognitive points of view, but for which the ontology developer could have used other simpler alternatives or more accurate ones for encoding the same knowledge. In the rest of this section we describe the antipatterns identied in each group, providing their name and acronym, their template logical expressions and a brief explanation of why this antipattern can appear and how it should be checked by the ontology developer. It is important to note that DLAPs generate unsatis- able classes that are normally identied by existing ontology debugging tools, although the information that is provided back to the user is not described ac- cording to such a pattern, what makes it dicult for ontology developers to nd a good solution according to their domain formalisation. With respect to CLAP and G, they are not detected by these tools as such, although in some cases their combination may lead to unsatisable classes that are detected (although not appropriately explained) by tools. As we mention in our future work section, we think that tool support for them could be a major step forward in this task.
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15 Lee mas

Landscape evolution and depositional processes in the Miocene Amazonian Pebas lake/wetland system: evidence from exploratory boreholes in northeastern Peru

Landscape evolution and depositional processes in the Miocene Amazonian Pebas lake/wetland system: evidence from exploratory boreholes in northeastern Peru

Key words – Miocene, Marañon basin, Peru, Pebas Formation, Chambira Formation, stratigraphy. This study of the type and scales of depositional processes and landscape development in western Am- azonia during the Miocene is based on the description and interpretation of three boreholes from the Marañon basin (Peru). The Miocene Pebas Formation, and the overlying Marañon Formation and un- derlying Chambira Formation are lithologically characterised. An age calculation model indicates an Oligocene age for the Chambira Formation, and an Early – early Late Miocene age for the Pebas Forma- tion. The base of the Chambira Formation is placed at a sequence boundary and corresponds to the be- ginning of a regression. The succession was deposited in fl oodplains included in a RST and a LST under a seasonal climate with a pronounced dry season. The base of the Pebas Formation is placed at a TS. It represents TST and HST lacustrine and swamp settings at or near sealevel, formed in a tropical mon- soon climate alike the present-day climate in the region. At the time, the area was a mosaic of lakes, swamps and fl uvial belts, but experienced tidal infl uence as well. During apparently regularly recurring base level highstands, open aquatic settings (lakes at sea level) were widespread. The depositional sys- tem was driven by tectonic subsidence in the area, uplift and erosion in the Andean hinterland and the western rim of the Pebas system (the developing Subandean zone), delta lobe switching and river belt avulsions, as well as presumable Milankovitch scale precipitation/erosion cycles and eustatic sea level variation. The base of the Marañon Formation is placed at a sequence boundary. It represents the end of the Pebas lake/wetland system, and the change to permanent fl uvial conditions during the Late Mi- ocene RST and LST.
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40 Lee mas

Liquid bridge formation

Liquid bridge formation

The formation process of a liquid bridge has been studied. The interest of this process lies in reducing the setting up time of experiments with liquid columns, due to time con- straints in performing experiments in space. In first place, some concepts of relevance to this study has been extracted from the literature. A dimensional analysis has been per- formed which allows to detect the dimensionless parameters of relevance, and a simplified model of the process has been developed valid for a < 1 (almost-steady evolution) and in a limited range of R and B. The simplified model is based in the assumption that the jet momentum gives rise to a pres-
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9 Lee mas

SECTION INSTRUMENT DE PLANIFICATION

SECTION INSTRUMENT DE PLANIFICATION

Action 15.1.3 - Pour les Parties qui ont des organismes d’aide au développement bilatéraux, répondre aux sections E1, E2, E5, E7, E10, E11, E14 et E15 des Lignes directrices pour la coopération internationale dans le cadre de la Convention sur les zones humides (Manuel Ramsar 9 pour l’utilisation rationnelle), et examiner en particulier des questions telles que des mécanismes propres à générer des fonds à long terme, le suivi approprié des projets, la formation du personnel des organismes d’aide au développement, la priorité à accorder au renforcement des institutions, la nécessité d’instaurer la coopération entre les organismes d’aide au développement et l’importance de la coordination entre les organizmes bilatéraux d’aide au développement et les Autorités administratives Ramsar dans les pays donateurs et les pays bénéficiaires.
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37 Lee mas

INSTRUMENT DE PLANIFICATION NATIONALE POUR L’APPLICATION DES DISPOSITIONS DE LA CONVENTION DE RAMSAR SUR LES ZONES HUMIDES

INSTRUMENT DE PLANIFICATION NATIONALE POUR L’APPLICATION DES DISPOSITIONS DE LA CONVENTION DE RAMSAR SUR LES ZONES HUMIDES

Action 15.1.3 - Pour les Parties qui ont des organismes d’aide au développement bilatéraux, répondre aux sections E1, E2, E5, E7, E10, E11, E14 et E15 des Lignes directrices pour la coopération internationale dans le cadre de la Convention sur les zones humides (Manuel Ramsar 9 pour l’utilisation rationnelle), et examiner en particulier des questions telles que des mécanismes propres à générer des fonds à long terme, le suivi approprié des projets, la formation du personnel des organismes d’aide au développement, la priorité à accorder au renforcement des institutions, la nécessité d’instaurer la coopération entre les organismes d’aide au développement et l’importance de la coordination entre les organizmes bilatéraux d’aide au développement et les Autorités administratives Ramsar dans les pays donateurs et les pays bénéficiaires.
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38 Lee mas

Contribution of artificial metaplasticity to pattern recognition

Contribution of artificial metaplasticity to pattern recognition

• In 2009 Tsui [104] applied a unsupervised learning technique to the problem of hardware variance degradation of the WiFi based localization systems. Although manual adjustment was able to reduce positional error, it was proposed to use an unsupervised learning method to automatically solve the hardware variance problem. • In 2010 Shen & Hasegawa [105] presented a Self-Organizing Incremental Neural Network (SOINN). SOINN was able to represent the topology structure of input data, incrementally learn new knowledge without destroy of learned knowledge, and process online non-stationary data. It was free of prior conditions such as a suitable network structure or network size, and it was also robust to noise. SOINN has been adapted for unsupervised learning, supervised learning, semi-supervised learning, and active learning tasks. Chang et al [106] studied the phenomenon of evaporation and the effects on the distribution of water in the hydrological cycle. The authors proposed a SOM to assess the variability of daily evaporation based on meteorological variables. The daily meteorological data sets from a climate gauge were collected as inputs to the SOM and then were classified into a topology map based on their similarities to investigate their relationships to assess their effort in the evaporation. To accurately estimate the daily evaporation based on the input pattern, the weights that connect the clustered centers in a hidden layer with the output were trained by using the least square regression method.
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282 Lee mas

Optimizing multi-core algorithms for pattern search

Optimizing multi-core algorithms for pattern search

In this work we use the OpenMP[OMP] library, which allows for a very simple implementation of intra-node shared memory parallelism by only adding a few compiler directives. The strategy is to distribute the NQ pattern queries between execution cores. The OpenMP parallelization is made with some simple changes to the sequential code. To avoid read/write conflict, every thread should have a local buff variable which stores a suffix of length L, also local left, right and cmp variables which are used to decide the subsection of the SA where to continue the search (see Fig. 2 above). To avoid using a critical section which incurs into an overhead (delay in execution time), we replace the result variable of Fig. 3 by an array results[1..NQ]. Therefore, each thread stores the results for the pattern Xi into results[i]. The “for” instruction is divided among all threads by means of the “#pragma omp for” directive. Fig. 4 shows the threaded execution using the OpenMP terminology. Also, the sched_setaffinity function is used in this implementation to obtain performance benefits and to ensure that threads are allocated in cores belonging to the same sockets.
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10 Lee mas

La lectura de Fitting the Pattern en el aula

La lectura de Fitting the Pattern en el aula

La obra de narrativa digital creada en el 2008 y modificada en el 2009 por Chris- tine Wilks es una obra interactiva, animada, producida en Flash (programa que ya no se comercializa pero con el que podemos seguir visualizando la obra si lo activamos) que como ella misma describía (Mencia, M y Husárová 2015, p. 37), es una memoria en piezas, en fragmentos. Son recuerdos a los que llegar cortándolos, cosiéndolos, prendiéndoles con alfileres, descosiendo el pasado, explorando la relación que tenía con su madre que era costurera. El crear esta memoria así se debe, según Wilks, a que los misterios de la vida no suelen estar dominados por la lógica o por un proceso lineal de deducción, sino que a él se llega a través de respuestas a ideas, a intuiciones, al azar, a fragmentos que nos surgen en nuestra mente. Y, solo con el tiempo se llega a construir la idea, pieza a pieza, cambiando las fechas, mezclando hasta llegar a ver el patrón que emerge. Señala que si nuestras memorias no son lineares, ¿por qué resistirse a ello? Pues no tienen un proceso lineal sino que son caóticas, desordenadas, fragmentadas, cíclicas, variables, etc. Esta ex- periencia es la que se intenta reproducir en Fitting the Pattern. Or being a dressmarker’s daughter. Por tanto es una memoria en piezas que puede ser explorada por el lector.
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14 Lee mas

Authenticator Pattern

Authenticator Pattern

The Authenticator pattern can be used to create a dialog between the requestor and the server prior to creating or granting access to a protected object. The negotiation can support identification (e.g., login), authentication (e.g., simple password, challenge response, multiple challenge responses), encryption method negotiation, key exchange, greatest common denominator version negotiation, parameterization of the protected object (i.e., a parameter to pass to the object factory for the protected object construction), and any other requirements of the application.

8 Lee mas

Materia resonante: patrones que correlacionan con modelos-in-formativos

Materia resonante: patrones que correlacionan con modelos-in-formativos

Similarly, we are composed of and by highly versatile encoded cells (i.e., stem cells and pacemaker cells) and hierarchically organized multi-cellular structures and organisms that are inextricably embedded within a rich and complex matrix of biological and physical phenomena. Investigating the inherent attributes of this pro- creative matrix can lead to insightfully understanding and appreciating the correlations between developmental processes, growth, form and reciprocally related multi-cellular configurations, patterns and metapatterns. This embodied-mind and environmentally embedded-body matrix offers a wealth of possible “readings” through its reciprocal relationship with the nature of the material world. The sheer complexity of this intricately layered interplay inspired the neurophysiologist Sir Charles Sherrington to rely on layered and interweaving metaphors centered around Jacquard’s Loom as a way to envision and describe the inner working of the human mind: “The brain is waking and with it the mind is returning. It is as if the Milky Way entered upon some cosmic dance. Swiftly the head-mass becomes an enchanted loom where millions of flashing shuttles weave a dissolving pattern, always a meaningful pattern though never an abiding one; a shifting harmony of sub-patterns. Now as the waking body rouses, sub-patterns of this great harmony of activity stretch down into the unlit tracks of the stalk-piece [spine] of the scheme. Strings of flashing and traveling sparks engage the lengths of it. This means that the body is up and rises to meet its waking day.” (Sherrington, p. 178).
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27 Lee mas

Spatial structures in nonlinear optical cavities at IFISC

Spatial structures in nonlinear optical cavities at IFISC

Depending on parameter values, DS develop different kinds of instabilities. Some instabilities, such as azimuthal instabilities, lead to the formation of an extended pattern. More interesting are the instabilities that, while preserving its localized character, induce the DS to start moving, breathing, or oscillating [8]. Remarkably enough, since DS can be considered as individual entities, these instabilities may lead to dynamical regimes that appear not to be present in the local dynamics of the extended system. In particular, we have shown the existence of a regime of excitability mediated by DS [9,10] in optical cavities filled with a nonlinear Kerr medium (Fig. 3). Excitability is a concept arising originally from biology (e.g., neuroscience) found in a variety of systems. Typically a system is said to be excitable if, while it sits at a stable steady state, perturbations beyond a certain threshold induce a large response before coming back to the rest state, while smaller perturbations decay immediately. We have also shown that coherence resonance, a typical behavior encountered in excitable systems when noise is
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7 Lee mas

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