A study of the relationship between cloud-to-ground lightning and precipitation in the convective weather system in China

International audienceIn this paper, the correlation between cloud-to-ground (CG) lightning and precipitation has been studied by making use of the data from weather radar, meteorological soundings, and a lightning location system that includes three direction finders about 40 km apart from each other in the Pingliang area of east Gansu province in P. R. China. We have studied the convective systems that developed during two cold front processes passing over the observation area, and found that the CG lightning can be an important factor in the precipitation estimation. The regression equation between the average precipitation intensity (R) and the number of CG lightning flashes (L) in the main precipitation period is R = 1.69 ln (L) - 0.27, and the correlation coefficient r is 0.86. The CG lightning flash rate can be used as an indicator of the formation and development of the convective weather system. Another more exhaustive precipitation estimation method has been developed by analyzing the temporal and spatial distributions of the precipitation relative to the location of the CG lightning flashes. Precipitation calculated from the CG lightning flashes is very useful, especially in regions with inadequate radar cover

Design of double-walled carbon nanotubes for biomedical applications

Double-walled carbon nanotubes (DWNTs) prepared by catalytic chemical vapour deposition were functionalized in such a way that they were optimally designed as a nano-vector for the delivery of small interfering RNA (siRNA), which is of great interest for biomedical research and drug development. DWNTs were initially oxidized and coated with a polypeptide (Poly(Lys:Phe)), which was then conjugated to thiol-modified siRNA using a heterobifunctional cross-linker. The obtained oxDWNT–siRNA was characterized by Raman spectroscopy inside and outside a biological environment (mammalian cells). Uptake of the custom designed nanotubes was not associated with detectable biochemical perturbations in cultured cells, but transfection of cells with DWNTs loaded with siRNA targeting the green fluorescent protein (GFP) gene, serving as a model system, as well as with therapeutic siRNA targeting the survivin gene, led to a significant gene silencing effect, and in the latter case a resulting apoptotic effect in cancer cells

Multi-instrumental analysis of large sprite events and their producing storm in southern France

During the night of 01-02 September, 2009, seventeen distinct sprite events including 3 halos were observed above a storm in north-western Mediterranean Sea, with a video camera at Pic du Midi (42.93N; 0.14E; 2877m). The sprites occurred at distances between 280 and 390km which are estimated based on their parent CG location. The MCS-type storm was characterized by a trailing-stratiform structure and a very circular shape with a size of about 70,000km2 (cloud top temperature lower than -35°C) when the TLEs were observed. The cloud to ground (CG) flash rate was large (45min-1) one hour before the TLE observation and very low (<5min-1) during it. Out of the 17 sprite events, 15 parent+CG (P+CG) strokes have been identified and their average peak current is 87kA (67kA for the 14 events without halo), while the associated charge moment changes (CMC) that could be determined, range from 424 to 2088±20%Ckm. Several 2-second videos contain multiple sprite events: one with four events, one with three events and three with two events. Column and carrot type sprites are identified, either together or separately. All P+CG strokes are clearly located within the stratiform region of the storm and the second P+CG stroke of a multiple event is back within the stratiform region. Groups of large and bright carrots reach ~70km height and ~80km horizontal extent. These groups are associated with a second pulse of electric field radiation in the ELF range which occurs ~5ms after the P+CG stroke and exhibits the same polarity, which is evidence for current in the sprite body. VLF perturbations associated with the sprite events were recorded with a station in Algiers. © 2012 Elsevier B.V

Observations of the relationship between sprite morphology and in-cloud lightning processes

[1] During a thunderstorm on 23 July 2003, 15 sprites were captured by a LLTV camera mounted at the observatory on Pic du Midi in the French Pyrénées. Simultaneous observations of cloud-to-ground (CG) and intracloud (IC) lightning activity from two independent lightning detection systems and a broadband ELF/VLF receiver allow a detailed study of the relationship between electrical activity in a thunderstorm and the sprites generated in the mesosphere above. Results suggest that positive CG and IC lightning differ for the two types of sprites most frequently observed, the carrot- and column-shaped sprites. Column sprites occur after a short delay (<30 ms) from the causative +CG and are associated with little VHF activity, suggesting no direct IC action on the charge transfer process. On the other hand, carrot sprites are delayed up to about 200 ms relative to their causative +CG stroke and are accompanied by a burst of VHF activity starting 25–75 ms before the CG stroke. While column sprites associate with short-lasting (less than 30 ms) ELF/VLF sferics, carrot sprites associate with bursts of sferics initiating at the time of the causative +CG discharge and persisting for 50 to 250 ms, indicating extensive in-cloud activity. One carrot event was found to be preceded by vigorous IC activity and a strong, long-lived cluster of ELF/VLF sferics but lacking a +CG. The observations of ELF/VLF sferic clusters associated with lightning and sprites form the basis for a discussion of the reliability of lightning detection systems based on VHF interferometry.Peer ReviewedPostprint (published version

The mesospheric inversion layer and sprites

The vertical structure of temperature observed by SABER (Sounding of Atmosphere using Broadband Emission Radiometry) aboard TIMED (Thermosphere, Ionosphere, Mesosphere Energetics and Dynamics) and sprites observations made during the Eurosprite 2003 to 2007 observational campaign were analyzed. Sprite observations were made at two locations in France, namely Puy de Dome in the French Massif Central and at the Pic du Midi in the French Pyrenees. It is observed that the vertical structure of temperature shows evidence for a Mesospheric Inversion Layer (MIL) on those days on which sprites were observed. A few events are also reported in which sprites were not recorded, although there is evidence of a MIL in the vertical structure of the temperature. It is proposed that breaking gravity waves produced by convective thunderstorms facilitate the production of (a) sprites by modulating the neutral air-density and (b) MILs via the deposition of energy. The same proposition has been used to explain observations of lightings as well as both MILs and lightning arising out of deep convections.Comment: 34 pages, 5figures. Accepted in Journal of Geophysical Research, US

Relativistic electron beams above thunderclouds

Non-luminous relativistic electron beams above thunderclouds have been detected by the radio signals of low frequency &amp;sim;40–400 kHz which they radiate. The electron beams occur &amp;sim;2–9 ms after positive cloud-to-ground lightning discharges at heights between &amp;sim;22–72 km above thunderclouds. Intense positive lightning discharges can also cause sprites which occur either above or prior to the electron beam. One electron beam was detected without any luminous sprite which suggests that electron beams may also occur independently of sprites. Numerical simulations show that beams of electrons partially discharge the lightning electric field above thunderclouds and thereby gain a mean energy of &amp;sim;7 MeV to transport a total charge of &amp;sim;−10 mC upwards. The impulsive current &amp;sim;3 &amp;times; 10&lt;sup&gt;&amp;minus;3&lt;/sup&gt; Am&lt;sup&gt;−2&lt;/sup&gt; associated with relativistic electron beams above thunderclouds is directed downwards and needs to be considered as a novel element of the global atmospheric electric circuit

Cellular localization, accumulation and trafficking of double-walled carbon nanotubes in human prostate cancer cells

Carbon nanotubes (CNTs) are at present being considered as potential nanovectors with the ability to deliver therapeutic cargoes into living cells. Previous studies established the ability of CNTs to enter cells and their therapeutic utility, but an appreciation of global intracellular trafficking associated with their cellular distribution has yet to be described. Despite the many aspects of the uptake mechanism of CNTs being studied, only a few studies have investigated internalization and fate of CNTs inside cells in detail. In the present study, intracellular localization and trafficking of RNA-wrapped, oxidized double-walled CNTs (oxDWNT–RNA) is presented. Fixed cells, previously exposed to oxDWNT–RNA, were subjected to immunocytochemical analysis using antibodies specific to proteins implicated in endocytosis; moreover cell compartment markers and pharmacological inhibitory conditions were also employed in this study. Our results revealed that an endocytic pathway is involved in the internalization of oxDWNT–RNA. The nanotubes were found in clathrin-coated vesicles, after which they appear to be sorted in early endosomes, followed by vesicular maturation, become located in lysosomes. Furthermore, we observed co-localization of oxDWNT–RNA with the small GTP-binding protein (Rab 11), involved in their recycling back to the plasma membrane via endosomes from the trans-golgi network

Symbiotic performance of Medicago ciliaris lines in association with different Sinorhizobium strains

We analyzed nodulation and nitrogen fixation efficiency for seven lines of Medicago ciliaris in association with two references strains of Sinorhizobium medicae (M104) and S. meliloti (RCR2011). These M. ciliaris lines were collected in Northern-East (Enfidha and Soliman) and Western (Rhayet and Mateur) Tunisian areas. The M. truncatula reference line Jemalong A17 (JA17) was also included. Plants were harvested after a culture period of 60 days. Two quantitative traits were measured at the harvest including the mean number of nodules per plant and the aerial dry weight (ADW). Analysis of variance showed that nodulation and nitrogen fixation efficiency (NFE) were dependent on the effects of line, strain and their interaction. The highest levels were observed for strain (45.07%) and line (53.24%) effects, respectively, for nodulation and NFE. While studied lines showed generally more number of nodules with RCR2011, they were more efficient with M104 strain. No significant difference in number of nodules was detected between M. ciliaris lines and JA17 with M104, whereas RCR2011 was generally most infective with JA17. Overall, JA17 line exhibited the largest NFE with both strains. Furthermore, there was no significant (P>0.05) correlation between nodulation and NFE for M. ciliaris line by strain associations

Characteristics and conditions of production of transient luminous events observed over a maritime storm

International audienceOn the night of 15/16 November 2007, cameras in southern France detected 30 transient luminous events (TLEs) over a storm located in the Corsican region (France). Among these TLEs, 19 were sprites, 6 were halos, and 5 were elves. For 26 of them, a positive “parent” cloud‐to‐ground lightning (P+CG) flash was identified. The peak current of the P+CG flashes for the sprites had an average value of 63 kA and had a maximum value of 125 kA. The flashes for the halos and the elves had average values of 272 and 351 kA, respectively, and they had maximum values of 312 and 384 kA, respectively. No TLEs were detected after negative CG flashes with very large peak currents. Among the 26 P+CG flashes, 23 were located in a stratiform region with reflectivity values lower than 45 dBZ. The CG flashes in this region were classified into two groups according to the time interval separating them from the following flash: one group with values less than 2 s and one with values greater than 2 s. About 79% of all CGs were produced in a sequence of at least two flashes less than 2 s apart. For 65.5% of the sequences, the first flash was positive with an average peak current of 73 kA, while the later +CG flashes in a sequence had much lower peak currents. Several triangulated sprites were found to be shifted from their P+CG flashes by about 10 to 50 km and preferentially downstream. The observations suggest that the P+CG flashes can initiate both sprites and other CG flashes in a storm

Building Information Modelling (BIM) value realisation framework for asset owners

The paper is presenting a value realisation framework for asset owners based on an exploratory study. The study is descriptive in nature and adopting a qualitative approach towards data collection. The paper adopts the viewpoint of BIM business value measurement considering that; (i) if the process is better as a result of BIM-based processes, then it is different in some relevant way; (ii) if it is different in some relevant way as a result of certain BIM properties or characteristics, then the change is observable; (iii) if the change is observ-able because of certain direct BIM benefits, then it is countable; (iv) if it is countable using defined measurement metrics, then it is measurable; (v) if it is measurable using established measurement techniques, an organisation can value each unit and therefore, realise the benefits of BIM. The specific contribution of paper is to improve asset owners’ understanding of BIM-business value measurement techniques and approaches