534 research outputs found
On the choosability of -minor-free graphs
Given a graph , let us denote by and ,
respectively, the maximum chromatic number and the maximum list chromatic
number of -minor-free graphs. Hadwiger's famous coloring conjecture from
1943 states that for every . In contrast, for list
coloring it is known that
and thus, is bounded away from the conjectured value for
by at least a constant factor. The so-called -Hadwiger's
conjecture, proposed by Seymour, asks to prove that
for a given graph (which would be implied by Hadwiger's conjecture). In
this paper, we prove several new lower bounds on , thus exploring
the limits of a list coloring extension of -Hadwiger's conjecture. Our main
results are:
For every and all sufficiently large graphs we have
, where
denotes the vertex-connectivity of .
For every there exists such that
asymptotically almost every -vertex graph with edges satisfies .
The first result generalizes recent results on complete and complete
bipartite graphs and shows that the list chromatic number of -minor-free
graphs is separated from the natural lower bound by a
constant factor for all large graphs of linear connectivity. The second
result tells us that even when is a very sparse graph (with an average
degree just logarithmic in its order), can still be separated from
by a constant factor arbitrarily close to . Conceptually
these results indicate that the graphs for which is close to
are typically rather sparse.Comment: 14 page
On the cost of misperception: general results and behavioural applications
In a choice model, we characterize the loss induced by misperceptions of payoff-relevant parameters across a distribution of decision problems. When the agent cannot avoid misperceptions but has some control over the distribution of errors, we show that strategies that minimize loss from misperception exhibit systematic biases, akin to some documented in the behavioural and psychological literatures. We include illusion of control, order effect, overprecision, and overweighting of small probabilities as illustrative examples
Attention please!
We study the impact of manipulating the attention of a decision-maker who learns sequentially about a number of items before making a choice. Under natural assumptions on the decision-maker’s strategy, directing attention toward one item increases its likelihood of being chosen regardless of its value. This result applies when the decisionmaker can reject all items in favor of an outside option with known value; if no outside option is available, the direction of the effect of manipulation depends on the value of the item. A similar result applies to manipulation of choices in bandit problems
Pflegen medienkompetente Eltern eine gute Medienerziehung? Ergebnisse einer Repräsentativbefragung von Eltern 10- bis 17-jähriger Kinder
"Eltern sehen sich gegenwärtig vor die Herausforderung der Medienerziehung in einer sich rasch entwickelnden neuen Medienlandschaft gestellt. In einer explorativen Studie wurde der Frage nachgegangen, welche Faktoren die Medienkompetenz und das medienerzieherische Handeln von Eltern 10- bis 17- jähriger Kinder beeinflussen. Im Fokus der Studie stehen insbesondere auch bisher nicht untersuchte Zusammenhänge zwischen der Medienkompetenz und dem medienerzieherischen Handeln der Eltern. Die Ergebnisse verdeutlichen die Notwendigkeit zielgruppenspezifischer Angebote zur Förderung der Medienkompetenz von Eltern. Bei der Ausgestaltung von Angeboten zur Förderung der Medienkompetenz sollten insbesondere der formale Bildungshintergrund und das Geschlecht der Eltern berücksichtigt werden." (Autorenreferat)"Parents today face challenges educating their children in a rapidly evolving new media landscape. This exploratory study investigates factors influencing media literacy and media education of parents of 10- to 17-year-old children. The study focuses in particular on the relationship between media literacy and media education of parents. The results highlight the need for targeted offers to promote media literacy among parents. In particular, the design of services for the promotion of media literacy should take into account the formal educational background and gender of parents." (author's abstract
Generation Smartphone : ein partizipatives Forschungsprojekt mit Jugendlichen
Unter www.generationsmartphone.ch finden Sie weitere Materialien (u.a. Videobeiträge), die aus dem Projekt entstanden sind.Im Projekt «Generation Smartphone» haben acht Erwachsene und acht Jugendliche gemeinsam zur Smartphone-Nutzung von dreissig Jugendlichen geforscht. Durch den partizipativen Forschungsansatz – Jugendliche beteiligen sich aktiv am Forschungsprozess – wurden die Sichtweisen der Jugendlichen systematisch miteinbezogen. Die Forschungsziele waren einerseits die Bedeutung des Smartphones im Alltag Jugendlicher zu erfassen und andererseits Chancen und Risiken der Smartphone-Nutzung aus Sicht der Jugendlichen sichtbar zu machen.
Einige wichtige Ergebnisse:
- Das Smartphone ist für fast alle Jugendlichen unverzichtbar im Alltag, weil in einem Gerät alles gebündelt ist: Musik, Fotoapparat, Wecker, Games, Mails, Videos/Fotos, das Internet, Kontaktmöglichkeit mit allen möglichen Menschen, Bücher, Stadtpläne.
- Viele Aktivitäten auf dem Smartphone sind vieles zugleich: Information, Unterhaltung und Kommunikation. «Spass» und «Ernsthaftes» sind nicht getrennt.
- Viele Jugendliche haben ambivalente Gefühle gegenüber dem Smartphone («es ist mein bester Freund und mein grösster Feind»): Es ermöglicht all das oben Aufgezählte, und gleichzeitig kann man sich ihm nicht entziehen.
- «Chancen» und «Risiken» treten oft gemeinsam auf: z.B. kann man ständig in Kontakt sein mit anderen Menschen, aber man muss auch ständig erreichbar sein und schnell reagieren. Man kann die meisten Risiken nicht durch einfache Massnahmen vermeiden, sie sind ein Teil des Gesamtpakets.
- Jugendliche nutzen ihre Smartphones sehr unterschiedlich, z.B. je nach Alter: vor allem jüngere Jugendliche spielen Games auf dem Smartphone, ältere Jugendliche verwenden es oft für die Schule
The evolution of GX 339-4 in the low-hard state as seen by NuSTAR and Swift
We analyze eleven NuSTAR and Swift observations of the black hole X-ray
binary GX 339-4 in the hard state, six of which were taken during the end of
the 2015 outburst, five during a failed outburst in 2013. These observations
cover luminosities from 0.5%-5% of the Eddington luminosity. Implementing the
most recent version of the reflection model relxillCp, we perform simultaneous
spectral fits on both datasets to track the evolution of the properties in the
accretion disk including the inner edge radius, the ionization, and temperature
of the thermal emission. We also constrain the photon index and electron
temperature of the primary source (the "corona"). We find the disk becomes more
truncated when the luminosity decreases, and observe a maximum truncation
radius of . We also explore a self-consistent model under the framework
of coronal Comptonization, and find consistent results regarding the disk
truncation in the 2015 data, providing a more physical preferred fit for the
2013 observations.Comment: 15 pages, 8 figures, 6 tables, accepted for publication in The
Astrophysical Journa
PARCOURS ATTENTIONNEL ET RÉGULARITÉS VISUOSPATIALES DANS L’ÉCRITURE
International audienceL’apprentissage de l’écriture est une activité complexe qui implique d’importantes modifications au niveau psychomoteur et cognitif chez l ’apprenant. Bien qu’essentiellement centrées sur la problématique du contrôle graphomoteur dans des tâches de tracés discrétisés (dimensions finies), les recherches et théories sur l’apprentissage de l’écriture mentionnent l’importance des régularités visuo-spatiales régissant les tracés entre eux dans l’espace d’écriture (dimensions ouvertes de type topologique). L’étude de la nature, du rôle et du fonctionnement de l’attention vis-à-vis de ces régularités nous guidera vers des hypothèses didactiques pouvant être complémentaires des approches existantes. Nous testerons celles-ci au travers de la conception et de l’expérimentation de dispositifs adaptatifs d’entrainement attentionnel (au sein du projet DESCRIPT, UTC, Gapenne), qui devront nous permettre d’observer l’émergence d’une pratique attentionnelle porteuse de stabilité et d’adaptabilité pour le tracé
Den digitalen Wandel konzeptionell fassen - das Beispiel Hochschule für Soziale Arbeit FHNW
Der Beitrag reflektiert den Erarbeitungsprozess des Grundlagenpapiers „Digitalisierung und Soziale Arbeit“ an der Hochschule für Soziale Arbeit FHNW. Ziel des Grundlagenpapiers ist es, den digitalen Wandel theoretisch zu rahmen und in seinen möglichen Auswirkungen für die Hochschule einzuschätzen. Der Artikel zeigt insbesondere auf, wie das Grundlagenpapier erarbeitet und das Thema Digitalisierung zu diesem Zweck anhand verschiedener Überlegungen dimensioniert wurde
Animazione socioculturale dell'infanzia e della gioventù
This book presents an overview of the results of the first standardised survey of services of open child and youth work in Switzerland, which was conducted in 2018 as a sub-project of the project Language Regions of the umbrella organisation Open Child and Youth Work Switzerland (DOJ/AFAJ) and other cooperation partners and was published in the three national languages of Switzerland which are German, French and Italian. A total of 620 services of open child and youth work, in which at least one permanently employed and/or paid professional worked, took part in the survey. In the book, the following aspects of the field of action are described in an overview and then contextualised: Types of services, opportunities for participation, quality work, professional orientation, financing, sponsorship and governance and management structures, statements on the target group, clients and staff, as well as on spatial or financial resources, founding year, opening hours etc., but also assessments of the professionals on specific topics. The results were also compared between the different linguistic regions and in the three different types of communes "urban", "intermediate" and "rural". The results of the study show a picture of a differentiated and complex field of action, illustrate achievements to date and point out the potential for future development
Offene Kinder- und Jugendarbeit
This book presents an overview of the results of the first standardised survey of services of open child and youth work in Switzerland, which was conducted in 2018 as a sub-project of the project Language Regions of the umbrella organisation Open Child and Youth Work Switzerland (DOJ/AFAJ) and other cooperation partners and was published in the three national languages of Switzerland which are German, French and Italian. A total of 620 services of open child and youth work, in which at least one permanently employed and/or paid professional worked, took part in the survey. In the book, the following aspects of the field of action are described in an overview and then contextualised: Types of services, opportunities for participation, quality work, professional orientation, financing, sponsorship and governance and management structures, statements on the target group, clients and staff, as well as on spatial or financial resources, founding year, opening hours etc., but also assessments of the professionals on specific topics. The results were also compared between the different linguistic regions and in the three different types of communes "urban", "intermediate" and "rural". The results of the study show a picture of a differentiated and complex field of action, illustrate achievements to date and point out the potential for future development
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