On the stability analysis of periodic sine-Gordon traveling waves

We study the spectral stability properties of periodic traveling waves in the sine-Gordon equation, including waves of both subluminal and superluminal propagation velocities as well as waves of both librational and rotational types. We prove that only subluminal rotational waves are spectrally stable and establish exponential instability in the other three cases. Our proof corrects a frequently cited one given by Scott.Comment: 22 pages, 6 figure

Annotating Synapses in Large EM Datasets

Reconstructing neuronal circuits at the level of synapses is a central problem in neuroscience and becoming a focus of the emerging field of connectomics. To date, electron microscopy (EM) is the most proven technique for identifying and quantifying synaptic connections. As advances in EM make acquiring larger datasets possible, subsequent manual synapse identification ({\em i.e.}, proofreading) for deciphering a connectome becomes a major time bottleneck. Here we introduce a large-scale, high-throughput, and semi-automated methodology to efficiently identify synapses. We successfully applied our methodology to the Drosophila medulla optic lobe, annotating many more synapses than previous connectome efforts. Our approaches are extensible and will make the often complicated process of synapse identification accessible to a wider-community of potential proofreaders

Knowing Values and Public Inspection

We present a basic dynamic epistemic logic of "knowing the value". Analogous to public announcement in standard DEL, we study "public inspection", a new dynamic operator which updates the agents' knowledge about the values of constants. We provide a sound and strongly complete axiomatization for the single and multi-agent case, making use of the well-known Armstrong axioms for dependencies in databases

Towards a computational- and algorithmic-level account of concept blending using analogies and amalgams

Concept blending–a cognitive process which allows for the combination of certain elements (and their relations) from originally distinct conceptual spaces into a new unified space combining these previously separate elements, and enables reasoning and inference over the combination–is taken as a key element of creative thought and combinatorial creativity. In this article, we summarise our work towards the development of a computational-level and algorithmic-level account of concept blending, combining approaches from computational analogy-making and case-based reasoning (CBR). We present the theoretical background, as well as an algorithmic proposal integrating higher-order anti-unification matching and generalisation from analogy with amalgams from CBR. The feasibility of the approach is then exemplified in two case studies

Peranan Elit dalam Rekonstruksi Budaya Lokal “Ingot-ingot” di Desa Panribuan Kabupaten Simalungun

The research was based on the strong position of a group of elite in a village in Karo Tribe called "Simantek kuta". Position is Obtained through elite role when Reconstructing a culture called "Ingot-ingot" meaning returning the favor. The purpose of this research was to know and describe the role of the elite in the reconstruction of the local culture Ingot-ingot in the village of Panribuan, Simalungun Regency. The theory used is the elite theory and the theory of cultural studies. The methods used by qualitative research. The technique of collecting data through observation, interviews, literature and documentation. This study yields findings where the reconstruction is done by doing a social approach, cultural hegemony and build relations of power in society. The culture of Ingot-ingot is a culture that is very sacred because when a debt of gratitude to appear then this debt is not just a personal debt but also debt into spirit, family debt, and debt of the ancestors, so that if not paid or dibalaskan then it can be a catastrophe. This definition is used by the elite through the power of capital in the form of material wealth and knowledge of the cultural aspects to revive culture of ingot-Ingot in an attempt to menghegemoni the community. Social approach undertaken to understand culture in a diverse community in the Batak tribe. This approach then yields the reconstruction of Ingot-ingots that was built through the existing cultural concept that already exist namely the awarding of "Jabatan" as the Organization of indigenous institutions, the granting of "Marga" as a form of tribal identity and "Perkawinan" in the concept formation of kinship. Elite calculations appear on each value from the third awarding it. On the other hand, the concept of marriage even produce power relations in the system of kinship

On the spectral and modulational stability of periodic wavetrains for nonlinear Klein-Gordon equations

In this contribution, we summarize recent results [8, 9] on the stability analysis of periodicwavetrains for the sine-Gordon and general nonlinearKlein-Gordon equations. Stability is considered both from the point of view of spectral analysis of the linearized problem and from the point of view of the formal modulation theory of Whitham [12]. The connection between these two approaches is made through a modulational instability index [9], which arises from a detailed analysis of the Floquet spectrum of the linearized perturbation equation around the wave near the origin. We analyze waves of both subluminal and superluminal propagation velocities, as well as waves of both librational and rotational types. Our general results imply in particular that for the sine-Gordon case only subluminal rotationalwaves are spectrally stable. Our proof of this fact corrects a frequently cited one given by Scott [11]

Crustal processes sustain Arctic abiotic gas hydrate and fluid flow systems

The Svyatogor Ridge and surroundings, located on the sediment-covered western flank of the Northern Knipovich Ridge, host extensive gas hydrate and related fluid flow systems. The fluid flow system here manifests in the upper sedimentary sequence as gas hydrates and free gas, indicated by bottom simulating reflections (BSRs) and amplitude anomalies. Using 2D seismic lines and bathymetric data, we map tectonic features such as faults, crustal highs, and indicators of fluid flow processes. Results indicate a strong correlation between crustal faults, crustal highs and fluid accumulations in the overlying sediments, as well as an increase in geothermal gradient over crustal faults. We conclude here that gas generated during the serpentinization of exhumed mantle rocks drive the extensive occurrence of gas hydrate and fluid flow systems in the region and transform faults act as an additional major pathway for fluid circulation