Regulation of Na-K-ATPase by arachidonic acid metabolites in intestinal epithelial cells

The integral membrane protein sodium potassium adenosine triphosphate (Na-K-ATPase), has been extensively studied in various animal cell models. Na-K-ATPase is a multifunctional enzyme which plays a significant role in cellular physiology by regulating electrochemical potential, cell volume, pH, cytosolic calcium, and many nutrient and electrolyte transport processes. As such, it has been implicated in the pathogenesis of inflammatory bowel diseases (IBD) and has been shown to play a vital role in the malabsorption of nutrients and electrolytes. In this context, a significant amount of research has been done over the last two decades to understand the mechanisms of alteration of various nutrient absorptive processes in IBD. Though it has been well acknowledged that Na-K-ATPase plays an essential role in the alteration of nutrient absorptive mechanisms during inflammation of the intestine, the molecular mechanisms responsible for the modulation of Na-K-ATPase in IBD was not known. To study the regulation of Na-K-ATPase, we used an in vitro model (rat intestinal epithelial cell line, IEC-18 cells) of intestinal epithelial cells that matured from the crypt to villus cells, very similar to that seen in the mammalian system. During the maturation process, these cells show an increase in Na-K-ATPase activity to support the absorptive capacity of the villus cells. The increased activity of Na-K-ATPase was found to be likely due to phosphorylation of the α1 subunit of Na-K-ATPase rather than altered transcription or trafficking of the enzyme. Numerous inflammatory mediators are produced during IBD; therefore, it is beneficial to uncover the role of individual inflammatory mediators in regulating transport processes regulated by Na-K-ATPase. We found that the inflammatory mediator leukotriene D4 (LTD4) stimulates the activity of Na-K-ATPase through a Ca-activated PKC pathway in crypt-like cells, while prostaglandin E2 (PGE2) reduces the activity of Na-K-ATPase through cAMP-activated PKA pathway in villus-like IEC-18 cells

Big Gulp Gets Even Bigger: Effects of Apparent Mass and Momentum Flux on the Forces during Baleen Whale Feeding

The feeding behavior of the Balaenoptera physalus, or more commonly known as fin whales, is some of the most extreme and somewhat curious feeding techniques among mammals and other aquatic vertebrate animals. The specific process includes a lunge deep into the ocean, and large gulp of water to catch many krill at one dive. These dives are relatively short due to the high energy expenditure, most likely due to the high drag exerted on the animal during the process. However, this drag is even more significant than previously thought. Due to the effects of apparent mass and momentum flux, the overall force is much greater than previously modeled. By mathematically modeling these effects during the lunge feeding process, researchers can have a more accurate understanding of additional inertial factors of ellipsoids, thus giving a better understanding in airship design

The SARFID technique for discriminating tagged items moving through a UHF-RFID gate

The discrimination of tagged items moving along a conveyor belt from other tagged items that are present in the scenario is investigated, when a UHF-RFID gate is installed at a conveyor section. Indeed, tagged items that are static or randomly moving in the scenario (nomad tags) around the reader antenna could be detected even if they are not on the conveyor (false positive readings). The classification procedure here proposed exploits the SARFID phase-based technique used to localize tags on a conveyor belt, which takes advantage of the fact that the tagged items move along a conveyor, whose path and instantaneous speed are both known. The latter can be implemented with only a firmware upgrade, in any conveyor belt scenario already equipped with an RFID system, without any modification of the system infrastructure and additional (reference tags/multiple antennas) or ad hoc hardware. From experimental results in a real scenario, the discrimination between moving tags from static/nomad tags can be obtained with an overall accuracy greater than 99.9%, by employing only one reader antenna

UHF-RFID desktop reader antennas: performance analysis in the near-field region

In this letter, a metric is proposed to qualitatively predict the achievable reading performance of a near-field (NF) UHF-RFID (865-928 MHz) desktop reader antenna, through a numerical analysis. Specifically, since the typical far-field antenna parameters (gain, radiation pattern, axial ratio) are not effective in the near-field region, the normalized power density is here proposed as a near-field antenna performance parameter. For a given NF antenna, the mean value of the normalized power density is evaluated on an area parallel to the antenna surface, at a set of different distances. Then, its decay rate is studied as a function of the distance from the antenna surface, which is useful to compare reading range performance of different antenna layouts. Additionally, the probability density function of the normalized power density at a given distance from the antenna surface is considered to investigate the field uniformity characteristics, the latter being important to guarantee tag reading independently on its location with respect to the reader antenna. The proposed analysis is applied to a set of NF UHF-RFID printed antennas, and conclusions are validated through a set of experimental tests

A reconfigurable layout for a self-structuring life-jacket-integrated antenna of a SAR system

A reconfigurable layout to implement a self-structuring wearable antenna for the local user terminal of a Search and Rescue system (Cospas-Sarsat at 406MHz) is presented. The proposed antenna layout has been designed for integration on a commercial life jacket for use in a maritime environment. The shape of the antenna can be reconfigured by means of RF switches to ensure the best possible transmission conditions, in terms of overall antenna efficiency, even if part of the antenna goes under the sea level. The shape of the components of the self-structuring antenna has been optimized for different antenna positions with respect to the water level and immersion angles

A phase-based technique for localization of uhf-rfid tags moving on a conveyor belt: Performance analysis and test-case measurements

A new phase-based technique for localization and tracking of items moving along a conveyor belt and equipped with ultrahigh frequency-radio frequency identification (UHF-RFID) tags is described and validated here. The technique is based on a synthetic-array approach that takes advantage of the fact that the tagged items move along a conveyor belt whose speed and path are known apriori. In this framework, a joint use is done of synthetic-array radar principles, knowledge-based processing, and efficient exploitation of the reader-tag communication signal. The technique can be easily implemented in any conventional reader based on an in-phase and quadrature receiver and it does not require any modification of the reader antenna configurations usually adopted in UHF-RFID portals. Numerical results are used to investigate the performance analysis of such methods, and also to furnish system design guidelines. Finally, the localization capability is also demonstrated through a measurement campaign in a real conveyor belt scenario, showing that a centimeter-order accuracy in the tag position estimation can be achieved even in a rich multipath environment

Electromagnetic analysis and performance comparison of fully 3D-printed antennas

In this work, the possibility of directly prototyping antennas by exploiting additive manufacturing 3D-printing technology is investigated. In particular, the availability of printable filaments with interesting conductive properties allows for printing of even the antenna conductive elements. Three samples of a 2.45 GHz microstrip patch antenna have been 3D-printed by using different approaches and materials, and their performance evaluated and compared. In particular, the same dielectric substrate printed in polylactic acid (PLA) has been adopted in all cases, whilst copper tape and two different conductive filaments have been used to realize the conductive parts of the three antenna samples, respectively. Even if an expected radiation efficiency reduction has been observed for the conductive filament case, the comparative analysis clearly demonstrates that 3D-printing technology can be exploited to design working fully-printed antennas, including the conductive parts

Experimental validation of a SAR-Based RFID localization technique exploiting an automated handling system

The synthetic aperture radar (SAR) approach has attracted a considerable interest in the context of phase-based techniques for the localization of UHF-RFID passive tags. In this letter, the results of an extensive experimental activity are presented, when the reader antenna is moved in front of a set of static passive UHF-RFID tags by means of a planar handling system. Measured performance is evaluated with respect to several system parameters: tag number and typology, tag reciprocal distance and orientation, trajectory and speed of the moving reader antenna. It is shown that the SAR processing can guarantee an accurate two-dimensional localization of multiple tags, with a localization error comparable to the size of typical commercial tags, by using a single reader antenna and without the need for any reference tag