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<p>Chloride ion channels are macromolecular pores providing for passage of chloride ions (and certain other inorganic and organic anions) through the cell membrane, down their electrochemical gradients. Chloride channels are differentially expressed in various cells, to best suit specific cellular activities. They are present in practically all living cells, and regardless of cell specialization they play an important role in vital housekeeping functions of cell-volume and pH regulation and in membrane potential stabilization. Regulation of cell volume underlies the structural integrity and constancy of the intracellular milieu. A variety of metabolic pathways have been shown to be sensitive to cell volume, and alterations of cell volume and osmoregulation processes can influence various intracellular signaling and organizing factors.</p><p>Volume-regulated anion channels (VRACs) are believed to play a pivotal role in cell-volume regulating processes. In this report I present data from macroscopic patch-clamp studies of VRACs performed in a fibroblast cell line and from single channel studies of chloride channels (tentatively related to VRACs) in mouse brown adipocytes in primary culture.</p><p>One of the characteristic features of the VRACs is their dependence on the presence of cytoplasmic ATP. In whole-cell experiments, removal of ATP from the pipette solution almost completely prevented activation of VRACs, whereas substitution of ATP with the nonhydrolyzable analog ATPγS did not alter the activation of VRACs. The inhibitors of protein tyrosine kinases (PTK) tyrphostin A25 and B46 depressed VRAC currents in both cases (ATP and ATPγS), but a PTK ineffective analog (tyrphostin A1) did not affect VRAC currents. We infer that in the cell preparation we used, ATP has a dual role in VRAC regulation: it is required for channel-protein phosphorylation and it can influence channel activity through non-hydrolytic binding in a ligand-receptor manner. It can additionally be suggested that tyrosine-specific protein kinases can be involved in the regulation of VRACs, independently of the effects of ATP. We also studied cell cycle-related changes in activation of VRACs by osmotic swelling of cells chemically arrested at different phases of the cell cycle. We found no significant changes during most of the cell cycle, except short periods before and after mitosis and in the quiescent G0 state.</p><p>The single Cl^-channels of brown adipocytes resemble in their electrophysiological phenotype outwardly rectifying Cl^- channels (ORCCs). We investigated the sensitivity of these channels to intracellular Ca²⁺. It appeared that the commonly used Ca²⁺-chelators EGTA and BAPTA could influence the ORCCs currents by themselves, independently of their calcium chelating effects. In some channels, these chelators induced classical flickery-type block of activity, whereas in others there was quasi-blockage, i.e. a peculiar combination of flickery blockage and overall channel activation. The chloride channel blocking agents DIDS and SITS mimicked the true/quasi blockage of EGTA and BAPTA. These phenomena add to the structure-function characteristics of the ORCC molecule. Moderate inhibitory effect of Ca²⁺ within a physiological range of intracellular concentrations (sub-µM) was also detected; however, the biological relevance of this observation, as well as of these Cl^- channels in general, remains to be clarified.</p>

Chloride ion channels are macromolecular pores providing for passage of chloride ions (and certain other inorganic and organic anions) through the cell membrane, down their electrochemical gradients. Chloride channels are differentially expressed in various cells, to best suit specific cellular activities. They are present in practically all living cells, and regardless of cell specialization they play an important role in vital housekeeping functions of cell-volume and pH regulation and in membrane potential stabilization. Regulation of cell volume underlies the structural integrity and constancy of the intracellular milieu. A variety of metabolic pathways have been shown to be sensitive to cell volume, and alterations of cell volume and osmoregulation processes can influence various intracellular signaling and organizing factors. Volume-regulated anion channels (VRACs) are believed to play a pivotal role in cell-volume regulating processes. In this report I present data from macroscopic patch-clamp studies of VRACs performed in a fibroblast cell line and from single channel studies of chloride channels (tentatively related to VRACs) in mouse brown adipocytes in primary culture. One of the characteristic features of the VRACs is their dependence on the presence of cytoplasmic ATP. In whole-cell experiments, removal of ATP from the pipette solution almost completely prevented activation of VRACs, whereas substitution of ATP with the nonhydrolyzable analog ATPγS did not alter the activation of VRACs. The inhibitors of protein tyrosine kinases (PTK) tyrphostin A25 and B46 depressed VRAC currents in both cases (ATP and ATPγS), but a PTK ineffective analog (tyrphostin A1) did not affect VRAC currents. We infer that in the cell preparation we used, ATP has a dual role in VRAC regulation: it is required for channel-protein phosphorylation and it can influence channel activity through non-hydrolytic binding in a ligand-receptor manner. It can additionally be suggested that tyrosine-specific protein kinases can be involved in the regulation of VRACs, independently of the effects of ATP. We also studied cell cycle-related changes in activation of VRACs by osmotic swelling of cells chemically arrested at different phases of the cell cycle. We found no significant changes during most of the cell cycle, except short periods before and after mitosis and in the quiescent G0 state. The single Cl- channels of brown adipocytes resemble in their electrophysiological phenotype outwardly rectifying Cl- channels (ORCCs). We investigated the sensitivity of these channels to intracellular Ca2+. It appeared that the commonly used Ca2+-chelators EGTA and BAPTA could influence the ORCCs currents by themselves, independently of their calcium chelating effects. In some channels, these chelators induced classical flickery-type block of activity, whereas in others there was quasi-blockage, i.e. a peculiar combination of flickery blockage and overall channel activation. The chloride channel blocking agents DIDS and SITS mimicked the true/quasi blockage of EGTA and BAPTA. These phenomena add to the structure-function characteristics of the ORCC molecule. Moderate inhibitory effect of Ca2+ within a physiological range of intracellular concentrations (sub-µM) was also detected; however, the biological relevance of this observation, as well as of these Cl- channels in general, remains to be clarified.

High quality perovskite manganites, La1-xAxMnO3 (A = Ca, Sr, Ba) are very attractive materials due to their great application potential for magnetic memory, uncooled infrared (IR) microbolometer and spintronics devices. This thesis presents studies of the growth and material characterization (including structural, electrical, magnetic and noise) of epitaxial manganite films on Si and GaAs. Furthermore, investigations about strain effect on structural and electrical properties of manganites, and finally fabrication of self-supported free standing microstructures for uncooled IR bolometer are also demonstrated. To obtain high quality epitaxial manganite films on semiconductor substrates at room temperature, using a combination of La0.67Sr0.33MnO3 (LSMO) and La0.67Ca0.33MnO3 (LCMO) compounds, La0.67(Sr,Ca)0.33MnO3 (LSCMO) films were successfully grown on Si substrates with Bi4Ti3O12(BTO)/CeO2/YSZ buffers by pulsed laser deposition (PLD) technique. Crystallographic relations between layers shows cube-on-cube for BTO/CeO2/YSZ/Si and diagonal-on-side for LSCMO films on BTO layer. 4.4 %K-1 maximum temperature coefficient of resistivity (TCR = 1/ρ·dρ/dT) and 2.9 %kOe-1 colossal magnetoresistance (CMR) were obtained at room temperature. Assuming of a prototype of temperature sensor, 1.2 μK/√Hz of noise equivalent temperature difference (NETD) and 2.9×108 cm√Hz/W of detectivity are expected to achieve at 294 K, 30 Hz. For GaAs substrates, using MgO buffer layer, LCMO films shows 9.0 %K-1 of TCR at 223 K while LSMO exhibits 2 %K-1 at 327 K. Systematic strain effects on structural and electrical properties of La0.75Sr0.25MnO3 LSMO) films on BTO/CeO2/YSZ-buffered Si, Si1-xGex/Si (compressive strain, x = 0.05-0.20) and Si1-yCy/Si (tensile, y = 0.01) were investigated. The strain induced from Si1-xGex/Si and Si0.99C0.01/Si has a tendency to decrease the roughness of CMR films compared to Si sample. High resistivity and low TCR values are observed for Si0.8Ge0.2/Si and Si0.99C0.01/Si samples due to excessive strains whereas Si0.9Ge0.1/Si and Si0.95Ge0.05/Si show slight improvements of films quality and TCR value. To fabricate LSCMO manganite bolometer on Si, wet etching with KOH and BHF and dry etching methods with Ar ion beam etching (IBE) were studied. For KOH wet etching, LSCMO films show high chemical resistance with lower than 0.2 nm/min of etch rate. BHF wet etching shows high etching selectivity over photoresist mask and silicon substrates. The etch rates for LSCMO and BTO layers are 22 and 17 nm/min. For Ar IBE, LSCMO films and oxide buffer layers show similar etch rates, 16-17 nm/min that are lower compared to 24 nm/min for Si. Free standing, self-supported heteroepitaxial LSCMO/BTO/CeO2/YSZ membranes for bolometer pixels on Si was successfully fabricated by Ar IBE and ICP etching techniques using a preannealed photoresist. The structural investigation by TEM revealed the sharp interfaces between layers. The electrical property of the free standing membrane was slightly degraded due to strain release and multi-step etching effect. These results demonstrate feasibility to use heteroepitaxial oxide structures as a thermally isolated membrane with conventional photoresist patterning. / QC 20101101

Wireless local area networks (WLANs) and wireless sensor networks (WSNs) technologies have been comprehensively developed and deployed during recent years. Since commercial WLAN and WSN products share the same free of license frequency band, the low power, low rate ZigBee based WSNs are vulnerable to the interference from Wi-Fi WLANs. Therefore, it is important to evaluate the performance of ZigBee WSNs that are subjected to interference generated by collocated Wi-Fi WLANs and to design effective counter-measuring techniques should performance improvement is needed. In this research, a versatile testbed for conducting various experiments is established and the ZigBee system’s performance with different clear channel assessment (CCA) modes and energy detection (ED) thresholds are evaluated through extensive experimental measurements in the testbed. It can be concluded from the results that CCA has significant impact on ZigBee’s performance. An existing theoretical analysis approach that is based on the collision time model between ZigBee and Wi-Fi packets is suitably modified to provide analytical evaluation means of the cases we examined. In order to mitigate the interference from the collocated Wi-Fi system, a novel and effective interference-aware adaptive CCA (IAACCA) scheme is proposed and implemented as firmware flashed into Crossbow motes. Experiments confirmed the ability of IAACCA to countermeasure effectively interference generated by Wi-Fi and thus improve the performance of ZigBee WSNs. Finally, a thorough statistical analysis is performed to understand the factors impacting the performance of ZigBee system and is used to further verify our experimental methods.

Vi lever idag i ett kommunikationsrikt samhälle där vi har möjlighet att dagligen delta i och höra ett flertal samtal. Samtalen kan vara av både formell och informell karaktär och kräver olika ansträngningar av oss. Av de här anledningarna vore det naturligt att vi övar oss i att samtala i skolan, speciellt eftersom mycket tyder på att samtal är en förutsättning för lärande. Syftet med den här studien är således att öka kunskap om hur samtal inleds i ett klassrum i svensk skola.   Ämnet har undersökts genom att videofilma fyra lektioner i en femteklass och därefter analysera materialet med hjälp av konversationsanalys (CA). Samtalsdeltagarna har varit de 21 elever, i åldrarna 11-12 år, som ingår i klassen och deras klasslärare. Resultatet visar bland annat att skillnader i typ av lektion påverkar vem som får tala. Under de lektioner som präglas av helklassdiskussioner tar läraren oftare initiativ till samtal och under sådana lektioner där eleverna arbetar självständigt inleder de oftare samtal. Slutligen kan sägas att mycket av elevernas möjlighet att initiera samtal påverkas av lärarens implicita metoder för att organisera undervisningen.

Industrial wireless sensor network (IWSN) is an application area of WSN used in industrial process monitoring and control with strict time and reliability requirement. WirelessHART standard is the first international standard for IWSN approved by International Electrotechnical Commission (IEC). This is worthwhile to implement this standard on simulator platform. Based on the study of WirelessHART standard, this thesis set up a primary implementation of the MAC layer of WirelessHART standard. To our best knowledge, this is the first comprehensive implementation of WirelessHART using OPNET simulator. The implementation has been evaluated rational. And some improvement of current implementation and standard have also been proposed and implemented. Flexible dedicated slot assignment has also been proposed to reduce the packet loss rate caused by influences of the physical channel.

Le problème du statut ontologique des universaux fut et demeure un des problèmes majeurs de la philosophie. Différentes réponses peuvent être apportées à ce problème. Nous chercherons ici à déterminer ce qu'aurait été la position défendue par Nicole Oresme. En nous fondant sur des questions tirées de son traité Expositio et Quaestiones in Aristotelis De Anima, nous exposerons la pensée oresmienne de la connaissance afin de nous donner l'instrumentation nécessaire à la réalisation du projet. La théorie de la connaissance qui émergera de ces questions sera comparée avec deux contemporains d'Oresme, à savoir Guillaume d'Ockham et Jean Buridan. Les théories de la connaissance de ces deux auteurs servent de références dans l'élaboration de la théorie de la connaissance d'Oresme et du statut ontologique à attribuer aux universaux. Nous chercherons à établir le nominalisme d'Oresme. De là émergera un nouveau problème: est-ce que l'on acquiert la connaissance d'une chose par l'entremise d'un concept avec comme représentation la singularité, ou bien est-ce que c'est par l'entremise d'un concept avec comme représentation l'universalité? L'hypothèse à laquelle notre recherche nous a conduit consiste à dire que chez Oresme il y a un concept qui est à la fois singulier et universel. La question se pose alors de savoir si on connaît premièrement une chose par l'entremise de l'universalité ou de la singularité de ce concept.

IEEE 802.15.4 is a standard defined for wireless sensor network applications with limited power and relaxed throughput needs. The devices transmit data during two periods: Contention Access Period (CAP) by accessing the channel using CSMA/CA and Contention Free Period (CFP), which consists of Guaranteed Time Slots (GTS) allocated to individual devices by the network coordinator. The GTS is used by devices for cyclic data transmission and the coordinator can allocate GTS to a maximum of only seven devices. In this work, we have proposed two algorithms for an efficient GTS allocation. The first algorithm is focused on improving the bandwidth utilization of devices, while the second algorithm uses traffic arrival information of devices to allow sharing of GTS slots between more than seven devices. The proposed schemes were tested through simulations and the results show that the new GTS allocation schemes perform better than the original IEEE 802.15.4 standard.

The Kuroshio, one of the most important western boundary currents of world, controls modern hydrology conditions of the East China Sea (ECS) and carries warm and saline water to high latitudes. Previous researches mentioned that the Kuroshio might change its flow path and volume in the ECS by East Asia monsoon (EAM), Equatorial climate conditions, or global sea level change during glacials. However, shifting or not of the Kuroshio out of the Okinawa Trough during Last Glacial Maximum (LGM) is still in debate. In this study, records derived from multi-proxies, include of Mg/Ca-based paleotemperatures and stable isotopes and foraminiferal census data, of core GH08-2004 was conducted for comparing with records derived from core MD012404 to understand the possible changes of the Kuroshio in the ESC since 26 ka. Our comparing results reveal that the surface hydrological environments have no obvious difference between eastern and western sides of the Ryukyu Arc and imply that the Kuroshio might not shifted outside of the OT during LGM. Otherwise, our reconstructed temperatures, oxygen isotopes and foraminiferal assemblages infer that the flowing volume of the Kuroshio was gradually increased since 19 ka associated with rising sea level. Thus we believe that emerged terrain caused by shallow sea level may be an important factor controlling the flowing path of the Kuroshio. In this study, differences of paleotemperatures and oxygen isotopes between G. ruber and N. dutertrei, surface and subsurface dweller, were decreased at the Holocene, whereas the delta values of carbon isotopes were larger meanwhile. This descrapncy implies that the East Asian winter and summer monsoons were enhanced synchronously.