Search results for "top-down"

The complexity of graph languages generated by hyperedge replacement

1990

Although in many ways, hyperedge replacement graph grammars (HRGs) are, among all graph generating mechanisms, what context-free Chomsky grammars are in the realm of string rewriting, their parsing problem is known to be, in general, NP-complete. In this paper, the main difficulty in HRG parsing is analysed and some conditions on either grammar or input graphs are developed under which parsing can be done in polynomial time. For some of the cases, the parsing problem is shown to be log-space reducible to context-free string parsing.

Rajallinen työmuisti S2-oppijoiden puheenymmärtämisvaikeuksien selittäjänä

2019

Tässä artikkelissa käsittelen työmuistin rajallisuuden ja aikuisten suomenoppijoiden puheenymmärtämisvaikeuksien yhteyttä tarkastelemalla oppijoiden kuuntelutehtäväsuorituksia ja niitä seuraavia stimulated recall -haastatteluja. Lisäksi selvitän, millaisilla muistitoiminnoilla oppijat kompensoivat työmuistin rajallisuutta ja helpottavat ymmärtämistä. Tutkimukseen osallistui 12 arabiankielistä alkeis- ja perustason aikuista suomenoppijaa, ja aineisto koostuu oppijoiden kuuntelutehtäväsuoritusten ja stimulated recall -haastattelujen videotallenteista. Työmuistin rajallisuuden vaikutus ymmärtämisvaikeuksissa tuli esiin erityisesti silloin, kun yhteen sanaan tai ilmaukseen keskittyminen aiheutt…

Bottom-up construction of dynamic density functional theories for inhomogeneous polymer systems from microscopic simulations

2020

We propose and compare different strategies to construct dynamic density functional theories (DDFTs) for inhomogeneous polymer systems close to equilibrium from microscopic simulation trajectories. We focus on the systematic construction of the mobility coefficient, $\Lambda(r,r')$, which relates the thermodynamic driving force on monomers at position $r'$ to the motion of monomers at position $r$. A first approach based on the Green-Kubo formalism turns out to be impractical because of a severe plateau problem. Instead, we propose to extract the mobility coefficient from an effective characteristic relaxation time of the single chain dynamic structure factor. To test our approach, we study…

Microfluidics and Macromolecules: Top-Down Analytics and Bottom-Up Engineering of Soft Matter at Small Scales

2016

Microfluidics is the art of creating and manipulating small portions of fluids. A typical variant of this art is fluid transport within small channels, either in form of laminar co-flow of miscible streams or in form of segmented-flow dripping and jetting of immiscible streams. Either method provides means to expose components of interest to defined local conditions such as spatially controlled concentration profiles that could not be established without the microfluidic auxiliaries. This ability renders microfluidics uniquely useful as both a method for advanced analytics and synthesis. This article sheds a spotlight on the use and utility of this method in macromolecular chemistry and phy…

Register affects language comprehension: ERP evidence from article omission in newspaper headlines

2011

Abstract Language processing involving syntax-discourse interface operations has been claimed to be particularly resource-consuming. In production, this additional complexity is claimed to be the source of article omission in the speech of young children and certain language-impaired speakers. In comprehension, article omission in some “special registers” (e.g., newspaper headlines) has been attributed to the trade-off between spending more processing resources and increasing processing speed. We investigated the comprehension of noun phrases (NPs) with and without articles (e.g., (a) policeman arrests (a) monk) when readers were or were not aware of reading headlines by recording electroph…

From top-down urban planning to culturally sensitive planning? Urban renewal and artistic activism in a neo-bohemian district in Barcelona

2020

The city of Barcelona in general and its historic center in particular have undergone a sea change from an industrial city to a global tourism and service center. Some authors argue that urban rene...

Ocean acidification as a driver of community simplification via the collapse of higher-order and rise of lower-order consumers

2017

AbstractIncreasing oceanic uptake of CO2 is predicted to drive ecological change as both a resource (i.e. CO2 enrichment on primary producers) and stressor (i.e. lower pH on consumers). We use the natural ecological complexity of a CO2 vent (i.e. a seagrass system) to assess the potential validity of conceptual models developed from laboratory and mesocosm research. Our observations suggest that the stressor-effect of CO2 enrichment combined with its resource-effect drives simplified food web structure of lower trophic diversity and shorter length. The transfer of CO2 enrichment from plants to herbivores through consumption (apparent resource-effect) was not compensated by predation, becaus…

Response of seagrasses and marine biofilms to natural acidification at CO2 vents

Nel corso degli ultimi 200 anni, circa il 30% delle emissioni antropogeniche di CO2 nell’atmosfera sono state assorbite dagli oceani, provocando un abbassamento medio dei livelli di pH oceanici pari a circa 0.1 unità. Questo fenomeno, noto come acidificazione degli oceani, sta determinando conseguenze negative sugli ecosistemi marini e sul loro funzionamento. Le attuali proiezioni climatiche suggeriscono che, in futuro, i cambiamenti climatici continueranno e si intensificheranno se non verranno adottate efficaci misure di mitigazione. Riuscire a valutare la risposta degli ecosistemi marini ai cambiamenti climatici costituisce una vera sfida per la ricerca scientifica, non solo per la diffi…

The Lean Urban Policies’ Design A values-centered method for sustainable urban planning.

In these past years, the necessity and urgency has emerged for policies tied to an alternate development to be efficiently applied, and not limited to single operations. The policies must be defined by a clear and effective method of action.
 Starting by investigating what are the relationship among human being, built environment and natural sources, in fact, we think it is possible to enrich the sustainable urban planning policies with new contents and possibly, new tools. By describing the frame, the objective is to define the most effective method, to be able to convey an effective project action and governance for the territory, to achieve predefined social and energy based objectives. …

Interferenza tra il livello dell’oggetto e attributi di base in stimuli visivi: studio su pazienti con lesione cerebrale.

2011

Introduzione. In compiti di ricerca visiva i processi top-down coinvolti nel riconoscimento della forma dell’oggetto possono interferire nella elaborazione bottom-up degli attributi elementari che compongono l’oggetto. La performance in tali compiti può essere facilitata dopo inibizione selettiva della corteccia parietale destra tramite r-TMS. In questo studio abbiamo indagato il ruolo di lesioni cerebrali nei compiti di ricerca visiva per singole caratteristiche caratterizzati da interferenza tra il livello dell’oggetto e degli attributi elementari. Pazienti con lesione focale del lobo parietale potrebbero paradossalmente non risentire dell’effetto interferente esercitato dal riconosciment…