Self-organization of channels and hillslopes in models of fluvial landform evolution and its potential for solving scaling issues

Including hillslope processes in models of fluvial landform evolution is still challenging. Since applying the respective models for fluvial and hillslope processes to the entire domain causes scaling problems and makes the results dependent on the spatial resolution, the domain is explicitly subdivided into channels and hillslopes in some models. The transition from hillslopes to channels is typically attributed to a given threshold catchment size as a proxy for a minimum required discharge. Here we propose a complementary approach for delineating channels based on the discrete representation of the topography. We assume that sites with only one lower neighbor are channelized. In combination with a suitable model for hillslope processes, this concept initiates the self-organization of channels and hillslopes. A numerical analysis with a simple model for hillslope dynamics reveals no scaling issues, so the results appear to be independent of the spatial resolution. The approach predicts a break in slope in the sense that all channels are distinctly less steep than hillslopes. On a regular lattice, the simple D8 flow-routing scheme (steepest descent among the eight nearest and diagonal neighbors) harmonizes well with the concept proposed here. The D8 scheme works well even when applied to the hillslopes. This property simplifies the numerical implementation and increases its efficiency.</p

Self-Organization and Regulation of Intrinsically Disordered Proteins with Folded N-Termini

How do mostly disordered proteins coordinate the specific assembly of very large signal transduction protein complexes? A newly emerging hypothesis may provide some clues towards a molecular mechanism

SH3 Domain-Mediated Recruitment of Host Cell Amphiphysins by Alphavirus nsP3 Promotes Viral RNA Replication

Among the four non-structural proteins of alphaviruses the function of nsP3 is the least well understood. NsP3 is a component of the viral replication complex, and composed of a conserved aminoterminal macro domain implicated in viral RNA synthesis, and a poorly conserved carboxyterminal region. Despite the lack of overall homology we noted a carboxyterminal proline-rich sequence motif shared by many alphaviral nsP3 proteins, and found it to serve as a preferred target site for the Src-homology 3 (SH3) domains of amphiphysin-1 and -2. Nsp3 proteins of Semliki Forest (SFV), Sindbis (SINV), and Chikungunya viruses all showed avid and SH3-dependent binding to amphiphysins. Upon alphavirus infection the intracellular distribution of amphiphysin was dramatically altered and colocalized with nsP3. Mutations in nsP3 disrupting the amphiphysin SH3 binding motif as well as RNAi-mediated silencing of amphiphysin-2 expression resulted in impaired viral RNA replication in HeLa cells infected with SINV or SFV. Infection of Balb/c mice with SFV carrying an SH3 binding-defective nsP3 was associated with significantly decreased mortality. These data establish SH3 domain-mediated binding of nsP3 with amphiphysin as an important host cell interaction promoting alphavirus replication

Analysis of a storm situation over the southern Baltic Sea using direct hydrometeorological and remote sensing measurements results

The paper presents results of research concerning meteorological and hydrological conditions in the storm related with the Xaver cyclone moving fast over the Baltic Sea. The analyses were based on remote sensing data from radars in Świdwin and Gdańsk-Rębiechowo and hydrometeorological data from direct measurements conducted at the coastal stations of the Polish Navy, marine stations of the Institute of Meteorology and Water Management, hydrometeorological station on the “Baltic Beta” oil rig and the Coastal Research Station of the Institute of Hydroengineering of the Polish Academy of Sciences in Lubiatowo. The assessment of the synoptic situation was made using surface weather charts, satellite images of cloud cover and meteorological radars products. The measurement data were used to analyze the surface and upper air wind fields for assessment of the hydrological situation (water condition, height and direction of the significant and maximum waves) and evaluation of threats to sea navigation and coastal infrastructure

Wind field numerical forecasts at high dynamic of pressure field changes

The paper presents an analysis of a rapid atmospheric process which in the beginning of December of 2013 moved over Europe from NNW in the form of a deep cyclone. The analysis aim is to verify the Weather Research & Forecasting Model results of daily numerical weather forecasts of extremely dynamic atmospheric processes. The applied spatial resolution of the computational grid of 36.3 km does not reveal the sub-grid processes. In case of the Xaver cyclone development and movement, the spatial step may be of significant importance. It is planned to analyze the case using data computed at better resolutions

A Real-Time PE-Malware Detection System Based on CHI-Square Test and PE-File Features

Part 11: Security and Network Technologies: SecurityInternational audienceConstructing an efficient malware detection system requires taking into consideration two important aspects, which are the accuracy and the detection time. However, finding an appropriate balance between these two characteristics remains at this time a very challenging problem. In this paper, we present a real-time PE (Portable Executable) malware detection system, which is based on the analysis of the information stored in the PE-Optional Header fields (PEF). Our system used a combination of the Chi-square (KHI2) score and the Phi (ϕ) coefficient as feature selection method. We have evaluated our system using Rotation Forest classifier implemented in WEKA and we reached more than 97% of accuracy. Our system is able to categorize a file in 0.077 seconds, which makes it adequate for real-time detection of malware

Driving forces behind phase separation of the carboxy-terminal domain of RNA polymerase II

Abstract Eukaryotic gene regulation and pre-mRNA transcription depend on the carboxy-terminal domain (CTD) of RNA polymerase (Pol) II. Due to its highly repetitive, intrinsically disordered sequence, the CTD enables clustering and phase separation of Pol II. The molecular interactions that drive CTD phase separation and Pol II clustering are unclear. Here, we show that multivalent interactions involving tyrosine impart temperature- and concentration-dependent self-coacervation of the CTD. NMR spectroscopy, molecular ensemble calculations and all-atom molecular dynamics simulations demonstrate the presence of diverse tyrosine-engaging interactions, including tyrosine-proline contacts, in condensed states of human CTD and other low-complexity proteins. We further show that the network of multivalent interactions involving tyrosine is responsible for the co-recruitment of the human Mediator complex and CTD during phase separation. Our work advances the understanding of the driving forces of CTD phase separation and thus provides the basis to better understand CTD-mediated Pol II clustering in eukaryotic gene transcription