840 research outputs found
Recommended from our members
Natural and anthropogenic rapid changes in the Kara-Bogaz Gol over the last two centuries reconstructed from palynological analyses and a comparison to instrumental records
Palynological analyses (pollen and dinocysts) of a sediment core taken in the Kara-Bogaz Gol have been used to
reconstruct rapid and catastrophic environmental changes over the last two centuries (chronology based on 210Pb). A
natural cyclicity (65 years) of water level changes in the Caspian Sea and in the Kara-Bogaz Gol and anthropogenic
factors (building of a dam separating the CS and the KBG waters) combine to induce rapid changes in water levels of
the KBG, in the salinity of its waters and in vegetation cover of its surroundings. The impact of low water levels on
the dinocysts is marked by a lower diversity and the survival of two species that are typical of the KBG, the Caspian
Sea species present in the KBG having disappeared. During periods of higher water levels (AD 1871 to 1878), the
lake is surrounded by a steppe-like vegetation dominated by Artemisia; whereas during periods of low water levels
(AD 1878 to 1913 and AD 1955-1998), the emerged shore are colonised by Chenopodiaceae. The period of AD 1913
to 1955 corresponding to decreasing water levels has an extremely low pollen concentration and a maximum of
reworking of arboreal taxa. During the last low-level period, humans responded by abandoning the shores of the bay.
What happened to the KBG can be used as an example of what may happen in the future for the Aral Sea.
A problem of reworking of Tertiary dinocysts into modern deposits has been detected owing to the knowledge of the
modern dinoflagellate assemblages recently made available through a water survey. A comparison to modern surface
pollen samples from Central Asia (Anzali, Caspian Sea south and central basins, Aral Sea, Lake Balkhash, Lake
Issyk-Kul and the Chinese Tien-Shan range) allows us to establish the potential reworking of at least five arboreal
pollen taxa possibly by run-off and dust storms
Dynamical properties of model communication networks
We study the dynamical properties of a collection of models for communication
processes, characterized by a single parameter representing the relation
between information load of the nodes and its ability to deliver this
information. The critical transition to congestion reported so far occurs only
for . This case is well analyzed for different network topologies. We
focus of the properties of the order parameter, the susceptibility and the time
correlations when approaching the critical point. For no transition to
congestion is observed but it remains a cross-over from a low-density to a
high-density state. For the transition to congestion is discontinuous
and congestion nuclei arise.Comment: 8 pages, 8 figure
Detection of Tephra Layers in Antarctic Sediment Cores with Hyperspectral Imaging
Tephrochronology uses recognizable volcanic ash layers (from airborne pyroclastic deposits, or tephras) in geological strata to set unique time references for paleoenvironmental events across wide geographic areas. This involves the detection of tephra layers which sometimes are not evident to the naked eye, including the so-called cryptotephras. Tests that are expensive, time-consuming, and/or destructive are often required. Destructive testing for tephra layers of cores from difficult regions, such as Antarctica, which are useful sources of other kinds of information beyond tephras, is always undesirable. Here we propose hyperspectral imaging of cores, Self-Organizing Map (SOM) clustering of the preprocessed spectral signatures, and spatial analysis of the classified images as a convenient, fast, non-destructive method for tephra detection. We test the method in five sediment cores from three Antarctic lakes, and show its potential for detection of tephras and cryptotephras.info:eu-repo/semantics/publishedVersio
SAFETY PATROL: MECHANISMS FOR IMPROVING EMERGENCY RESPONSE TIMES
To equip first responders with critical, time-sensitive information and accelerate emergency services response times, various solutions are provided herein through several techniques. Under a first technique, after an emergency event such as a gunshot is either automatically detected by a camera or manually initiated by a user, or when a dangerous object such as a gun is detected by a camera, a network may react by associating the source of the dangerous event or object with a person based on proximity data; identifying the physical characteristics of the person (such as height, hair color, clothing, visible tattoos, etc.); attaching such characteristics as textual metadata; and then transmitting that metadata to first responders. A second technique automatically develops a radio frequency (RF) signature profile of a person of interest (from RF signals emitted by devices carried by the person), associates that profile to the person, and leverages that profile to track the person as they move throughout a building or campus, allowing a user to look back in time (to, for example, identify where a person came from and how they entered a building) by tracking the RF profile over time. The above-described data is extremely important during any ongoing emergency and equips first responders with critical information which only a network can provide
Quaternary evolution of the lower calore and middle volturno valleys (Southern Italy)
The lower Calore and middle Volturno valleys preserve stratigraphical and morphological evidence and tephrostratigraphic markers particularly suitable for reconstructing the long-term geomorphological evolution of the central-southern Apennines. Aim of our study is to identify the main steps of the Quaternary landscape evolution of these valley systems and to improve knowledge about the relationships between fluvial processes and tectonics, volcanic activity, climatic and human influences. To this purpose, we carried out an integrated geomorphological and chronostratigraphical analysis of identified fluvial landforms and related deposits, integrated by230Th/234U datings on travertines from the Telese Plain area. The study highlighted in particular: (1) fluvial sedimentation started in the Middle Pleistocene (~650 ka) within valleys that originated in the lower Pleistocene under the control of high-angle faults; (2) extensional tectonics acted during the Middle and Upper Pleistocene, driving the formation of the oldest fluvial terraces and alluvial fans, and persisted beyond the emplacement of the Campanian Ignimbrite pyroclastic deposits (~39 ka); and (3) from the late Upper Pleistocene onwards (<15 ka), the role of tectonics appears negligible, while climatic changes played a key role in the formation of three orders of valley floor terraces and the youngest alluvial fans
Ultra Wideband Impulse Radio Superregenerative Reception
Postprint (published version
Prediction of the Caspian Sea level using ECMWF seasonal forecasts and reanalysis
This article is made available through the Brunel Open Access Publishing Fund. This article is distributed under the terms of the Creative Commons Attribution License which permits any use, distribution, and
reproduction in any medium, provided the original author(s) and the
source are credited.The hydrological budget of the Caspian Sea (CS) is investigated using the European Centre for Medium-Range Weather Forecasts interim reanalysis (ERAi) and seasonal forecast (FCST) data with the aim of predicting the Caspian Sea Level (CSL) some months ahead. Precipitation and evaporation are used. After precipitation events over the Volga River, the discharge (Volga River discharge (VRD)) follows with delays, which are parameterized. The components of the water budget from ERAi and FCSTs are integrated to obtain time series of the CSL. Observations of the CSL and the VRD are used for comparison and tuning. The quality of ERAi data is sufficiently good to calculate the time variability of the CSL with a satisfactory accuracy. Already the storage of water within the Volga Basin allows forecasts of the CSL a few months ahead, and using the FCSTs of precipitation improves the CSL forecasts. The evaporation in the seasonal forecasts is deficient due to unrealistic sea surface temperatures over the CS. Impacts of different water budget terms on the CSL variability are shown by a variety of validation tools. The importance of precipitation anomalies over the catchment of the Volga River is confirmed, but also impacts from the two southern rivers (Sefidrud and Kura River) and the evaporation over the CS become obvious for some periods. When pushing the FCSTs beyond the limits of the seasonal FCSTs to 1 year, considerable forecast skill can still be found. Validating only FCSTs by the present approach, which show the same trend as one based on a statistical method, significantly enhances the skill scores
Active site-directed inhibitors of prolyl oligopeptidase abolishes its conformational dynamics
Deciphering conformational dynamics is crucial for understanding the biological functions of proteins and for designing compounds targeting them. In particular, providing an accurate description of microsecond-millisecond motions opens the opportunity for regulating protein-protein interactions (PPIs) by modulating the dynamics of one interacting partner. Here we analyzed the conformational dynamics of prolyl oligopeptidase (POP) and the effects of active-site-directed inhibitors on the dynamics. We used an integrated structural biology approach based on NMR spectroscopy and SAXS experiments complemented by MD simulations. We found that POP is in a slow equilibrium in solution between open and closed conformations, and that inhibitors effectively abolished this equilibrium by stabilizing the enzyme in the closed conformation
- …