Division of labour among culms in the clonal reed Arundo donax (Poaceae) is underlain by their pre-determined hydraulic structure

Clonal plants present an interesting example of division of labour among their ramets. Here we elaborated on hydraulic structure in respect to the division of labour among ramets in Arundo donax, a perennial clonal reed. Mature clones have three shoot types: (1) large mostly flowering; (2) medium mostly vegetative and (3) small vegetative. The shoots grow from buds initiating in the upper side of underground rhizomes, and the shoot growth is primary with vasculature produced from the procambium. We tested whether the number of vascular strands in a shoot has a fixed developmental programme or follows a flexible developmental pattern, and we found that the number of vascular strands strongly differs between shoot types. Large shoots on average have 560 vascular strands with both the widest vessels and significantly highest hydraulic conductivity. Medium ones and small shoots have 409 and 102 on average, respectively, with narrower vessels and with low conductivity. Thus, the shoot apices have three alternative developmental programmes. Apparently, a clone is built of functionally different modular units that enable Arundo donax to maximize its potential in a heterogeneous environment. Although the smaller culms do not contribute directly to the sexual reproduction of the clone, under stress their safer hydraulic system offers them a better chance of survival.

An Image Reconstruction Algorithm with Experimental Validation for Electrical Impedance Tomography Imaging Applications

In the Non-Invasive Bio Impedance Technique (NIBIT) a low current pulse with high frequency inserted between two electrodes of the object while measuring voltages from the other remaining electrodes with respect to the reference electrode. The electrode arrangement is defined in the form of cylindrical shapes of the surface of the phantom. After these arrangements, it inserts the current pulse and measures the voltages according to the selected data acquisition method of bio impedance. The presented algorithm analyzes and defines each obtained data sample from the used phantoms and also allows Image Reconstruction (IR) based on developed Graphical User interface (GUI) on MATLAB. The used IR approach is based on Tikhonov regularization and FEM. The FEM and Tikhonov regularization are mathematical approaches that deal with Forward Problem (FP) and Inverse Problem (IP) of images. In our approach, the FP solution is identified first in order to reconstruct the conductivity distribution through the EIT inverse solution. Thereafter, This FP is solved through the known current pulse of a given conductivity medium. Likewise, the IP is identified and solved through the boundary potential of the object. The end of the obtained result provides a comparable result for the used phantom according to its internal structure. This proposed technique is still reliable despite having some standardization issue according to the procedure.

Lab-On-A-Chip Device for Yeast Cell Characterization in Low-Conductivity Media Combining Cytometry and Bio-Impedance

This paper proposes a simple approach to optimize the operating frequency band of a lab-on-a-chip based on bio-impedance cytometry for a single cell. It mainly concerns applications in low-conductivity media. Bio-impedance allows for the characterization of low cell concentration or single cells by providing an electrical signature. Thus, it may be necessary to perform impedance measurements up to several tens of megahertz in order to extract the internal cell signature. In the case of single cells, characterization is performed in a very small volume down to 1 pL. At the same time, measured impedances increase from tens of kilo-ohms for physiological liquids up to several mega-ohms for low conductivity media. This is, for example, the case for water analysis. At frequencies above hundreds of kilohertz, parasitic effects, such as coupling capacitances, can prevail over the impedance of the sample and completely short-circuit measurements. To optimize the sensor under these conditions, a complete model of a cytometry device was developed, including parasitic coupling capacitances of the sensor to take into account all the impedances. It appears that it is possible to increase the pass band by optimizing track geometries and placement without changing the sensing area. This assumption was obtained by measuring and comparing electrical properties of yeast cells in a low-conductivity medium (tap water). Decreased coupling capacitance by a factor higher than 10 was obtained compared with a previous non-optimized sensor, which allowed for the impedance measurement of all electrical properties of cells as small as yeast cells in a low-conductivity medium.

Precursory Response of Low Frequency Signals for Detection of Seismic Rapture in Indian Region

Recognition of seismic precursors is exigent task. Its study depends upon the environmental parameters, ground motion emissions (Low frequency signals), geological and tectonic structure. The theory of signal conductivity of two crust model between the epicenter region and above the ground surface calculated the amplitude enhancement of electromagnetic emissions. Extremely low frequency signals generate due to seismic emissions and penetrate the crystal layer to change the earth’s surrounding and upper atmosphere conditions. These outputs are used to correlate the seismogenic VLF signals (f=3 KHz), which are recorded by borehole antenna system. It is observed that the low frequency signals goes to vertically and accumulated as low conductivity medium in the outer most layer through which transmitted to the atmosphere. The seismogenic ULF emissions, DEMETER satellite data, TEC anomalies, ionospheric disturbances and bio-electric amplitude was recorded at places nearby active fault line in Indian region and it is used to recognized the pre- seismic behaviour. We have also observed the stimulus data (solar flux, audio frequency signals, or electric charge emissions) as abnormal signals. These relations are verified and correlated by statistical analysis with null hypothesis testing and power spectrum magnitude which is helping us to understand the precursory signature of earthquakes.

Impact of glycerol on Zinc Oxide based thin film transistors with Indium Molybdenum Oxide electrodes

ABSTRACTThin-film transistors (TFT) were fabricated at a room-temperature (RT) with zinc oxide (ZnO) channel and indium molybdenum oxide (IMO) electrodes. To isolate the gate oxide and gate electrode influence on the device performance, common gate configuration on a commercial substrate with thermal SiO2 (100 nm) was selected. A threshold voltage (VTh) of 10 V and ION/IOFF ratio of 1 × 10-5 were obtained. Once the reference data was taken transistors were exposed to glycerol. Temporary changes in device characteristics were observed due to the influence of glycerol, a low conductivity medium. To exclude the possibility of sugar alcohol being the main conductor, measurement on dummy transistor electrode was performed retaining the distance between probes. The TFT device under test revealed ten times higher drain current but also a change in threshold voltage and leakage current. Transistors under glycerol influence were always open with the positive gate bias.