Spelling suggestions: "subject:"ensitive"" "subject:"asensitive""
11 |
Characterisation of the Redox Sensitive NMDA ReceptorAlzahrani, Ohood 05 1900 (has links)
Glucose entry into the brain and its subsequent metabolism to L-lactate, regulated by
astrocytes, plays a major role in synaptic plasticity and memory formation. A recent
study has shown that L-lactate produced by the brain upon stimulation of glycolysis, and
glycogen-derived L-lactate from astrocytes and its transport into neurons, is crucial for
memory formation.
A recent study revealed the molecular mechanisms that underlie the role of L-lactate in
neuronal plasticity and long-term memory formation. L-lactate was shown to induce a
cascade of molecular events via modulation of redox-sensitive N-Methyl-D-aspartate
(NMDA) receptor activity that was mimicked by nicotinamide adenine dinucleotide
hydride (NADH) co-enzyme. This indicated that changes in cellular redox state,
following L-lactate transport inside the cells and its subsequent metabolism, production
of NADH, and favouring a reduced state are the key effects of L-lactate. Therefore, we
are investigating the role of L-lactate in modulating NMDA receptor function via redox
modulatory sites. Accordingly, crucial redox-sensitive cysteine residues, Cys320 and
Cys87, of the NR2A NMDA receptor subunit are mutated using site-directed mutation,
transfected, and expressed in HEK293 cells. This cellular system will then be used to characterise and monitor its activity upon Llactate
stimulation, compared to the wild type. This will be achieved by calcium imaging,
using fluorescent microscopy.
Our data shows that L-lactate potentiated NMDA receptor activity and increased
intracellular calcium influx in NR1/NR2A wild type compared to the control condition
(WT NR1/NR2A perfused with (1μM) glutamate and (1μM) glycine agonist only),
showing faster response initiation and slower decay rate of the calcium signal to the
baseline. Additionally, stimulating with L-lactate associated with greater numbers of cells
having high fluorescent intensity (peak amplitude) compared to the control. Furthermore,
L-lactate rescued the mutated NMDA NR1/NR2A C320A C87A receptor response that
showed altered activity upon mutation up to the control level. Future experiments need to
be carried out on different redox-sensitive residues of various NMDA receptor subunits
to reveal the exact molecular mechanisms of L-lactate.
|
12 |
A sensitive spectropolarimeter for the measurement of circular polarization of luminescenceAl-Akir, Ziad I. January 1990 (has links)
No description available.
|
13 |
Delay Sensitive Routing for High Speed Packet-switching Networks / 高速封包交換網路中考量網路延遲的路由黃玉昇, Yu-Sheng Huang Unknown Date (has links)
在如同全IP網路(ALL-IP Network)這類的分封交換網路(packet-switching network)中提供具時效性的服務(time-sensitive services)必須嚴格的控制時間。路由規劃是網路管理中重要的一環,所以這類網路的路由規劃必須考慮網路延遲。然而就我們目前所知,多數的傳統路由演算法並不以傳輸延遲(path delay)為主要考量因素;例外少數有考量延遲時間的演算法也僅限於鍊結延遲(link delay),而未考慮節點延遲(node delay)。此乃肇因於以往頻寬的成本極為昂貴,因而造成演算法設計者在設計時會儘可能有效利用頻寬,如此免不了會犧牲傳遞速度。在過去幾年間,由於光通訊技術的提升,網路頻寬的成長速度遠遠已超過路由器(router)處理能力的成長。在這樣不對等的成長比例驅使下,節點延遲,亦即路由器處理封包時所耗時間,在傳輸延遲中所佔的比例亦隨之快速增長。也因此我們認為,在為高速封包交換網路設計路由演算法時,必須同時考量鍊結延遲和節點延遲。在本論文中,我們設計了一個訊務流為基礎的路由演算法(flow-based routing algorithm),KLONE,來驗證我們的論點。在規劃路由時,KLONE會把發生在鍊結和節點上的延遲時間一併列入計算,並以全體延遲時間為主要考量。透過我們反覆的測試實驗,我們發現其較之於常用的OSPF演算法,可以在效能上有30%的勝出。藉此,我們的論點得到初步的證實。 / Providing time sensitive services becomes an essential task for some packet-switching networks such as All-IP networks, which will carry all the traffics supported by both circuit-switching and packet-switching networks. To fulfill this demand, such networks require a delay sensitive routing mechanism to provide time-related QoS for delay sensitive services. However, most of traditional routing algorithms do not take delay time as a major concern. Only a few are designed for time sensitive services. These time sensitive routing algorithms are designed at the time when the link bandwidth is the only scarce resource. As the bandwidth of communication links grows rapidly in recent years due to the advance of optical communication technologies, link bandwidth is no longer the only scarce resource. The processing speed of nodes, for example, routers, becomes another critical source of delay time. In this thesis, we designed a new flow-based routing algorithm, the KLONE algorithm, which takes average delay time as its minimization objective and takes both nodes and links as delay components. Through an intensive evaluation using simulation method, we demonstrate that a routing algorithm that considers both link and node delay might outperform the traditional OSPF algorithm.
|
14 |
A multiple criteria decision-making approach to establishing environmental and economic trade-offs in Pennine Dales agricultureBarron, Nicola-Jo January 1997 (has links)
No description available.
|
15 |
Ion-selective field-effect transistors with fast atom bombardment sputtered membranes for pH, sodium and potassium measurementDodgson, John January 1995 (has links)
No description available.
|
16 |
The Development of a Sensitive Manipulation End EffectorColeman, Catherine 10 February 2014 (has links)
This thesis designed and realized a two-degree of freedom wrist and two finger manipulator that completes the six-degree of freedom Sensitive Manipulation Platform, the arm of which was previously developed. This platform extends the previous research in the field of robotics by covering not only the end effector with deformable tactile sensors, but also the links of the arm. Having tactile sensors on the arm will improve the dynamic model of the system during contact with its environment and will allow research in contact navigation to be explored. This type of research is intended for developing algorithms for exploring dynamic environments. Unlike traditional robots that focus on collision avoidance, this platform is designed to seek out contact and use it to gather important information about its surroundings. This small desktop platform was designed to have similar proportions and properties to a small human arm. These properties include compliant joints and tactile sensitivity along the lengths of the arms. The primary applications for the completed platform will be research in contact navigation and manipulation in dynamic environments. However, there are countless potential applications for a compliant arm with increased tactile feedback, including prosthetics and domestic robotics. This thesis covers the details behind the design, analysis, and evaluation of the two degrees of the Wrist and two two-link fingers, with particular attention being given to the integration of series elastics actuators, the decoupling of the fingers from the wrist, and the incorporation of tactile sensors in both the forearm motor module and fingers.
|
17 |
Plant Spacing: A Size Sensitive Model With Implications for CompetitionBayn, Robert L, Jr. 01 May 1982 (has links)
An algorithm is presented which partitions space among mapped plants according to their relative sizes and positions using one of eight rules for locating boundaries between individuals. The performance of those rules is examined using several natural and artificial data sets with diverse measures of individual size. The relative performance of the rules was the same for all natural data sets examined. The best rule, as measured by a high correlation between individual size and assigned space, placed the boundary at a distance between neighbors proportional to the relative sizes of neighbors as long as a maximum distance (also a function of size) was not exceeded. It is inferred that the algorithm identifies contact neighbors and quantifies the extent of their contact. Afield experiment is proposed to test this inference.
|
18 |
Fabrication and Characterization of Photon Radiation DetectorsMattsson, Claes January 2007 (has links)
<p>This thesis involves a study the fabrication and characterization of photon radiation detectors. The focus has been to develop and improve the performance of optical measurement systems, but also to reduce their cost. The work is based on the study of two types of detectors, the position sensitive detector and the thermal detector.</p><p>Infrared detectors are usually subcategorized into photonic detectors and thermal detectors. In the thermal detectors, heat generated from the incident infrared radiation is converted into an electrical output by some sensitive element. The basic structure of these detectors consists of a temperature sensitive element connected to a heat sink through a thermally isolating structure. Thin membranes of Silicon and Silicon nitride have been commonly used as thermally insulation between the heat sink and the sensitive elements. However, these materials suffer from relatively high thermal conductivity, which lowers the response of the detector. The fabrication of these membranes also requires rather advanced processing techniques and equipment. SU-8 is an epoxy based photoresist, which has low thermal conductivity and requires only standard photolithography. A new application of SU-8 as a self-supported membrane in a thermal detector is presented. This application is demonstrated by the fabrication and characterization of both an infrared sensitive thermopile and a bolometer detector. The bolometer consists of nickel resistances connected in a Wheatstone bridge configuration, whereas the thermopile uses serially interconnected Ti/Ni thermocouple junctions.</p><p>The position sensitive detectors include the lateral effect photodiodes and the quadrant detectors. Typical applications for these detectors are distance measurements and as centering devices. In the quadrant detectors, the active region consists of four pn-junctions separated by a narrow gap. The size of the active region in these detectors depends on the size of the light spot. In outdoor application, this spot size dependence degrades the performance of the four-quadrant detectors. In this thesis, a modified four-quadrant detector having the pn-junctions separated by a larger distance has been fabricated and characterized. By separating the pn-junctions the horizontal electric filed in the active region is removed, making the detector spot size insensitive.</p><p>Linearity of the lateral effect photodiodes depends on the uniformity of the resistive layer in the active region. The introduction of mechanical stress in an LPSD results in a resistance change mainly due to resistivity changes, and this affects the linearity of the detector. Measurements and simulations, where mechanical stress is applied to LPSDs are presented, and support this conclusion.</p>
|
19 |
Fabrication and Characterization of Photon Radiation DetectorsMattsson, Claes January 2007 (has links)
This thesis involves a study the fabrication and characterization of photon radiation detectors. The focus has been to develop and improve the performance of optical measurement systems, but also to reduce their cost. The work is based on the study of two types of detectors, the position sensitive detector and the thermal detector. Infrared detectors are usually subcategorized into photonic detectors and thermal detectors. In the thermal detectors, heat generated from the incident infrared radiation is converted into an electrical output by some sensitive element. The basic structure of these detectors consists of a temperature sensitive element connected to a heat sink through a thermally isolating structure. Thin membranes of Silicon and Silicon nitride have been commonly used as thermally insulation between the heat sink and the sensitive elements. However, these materials suffer from relatively high thermal conductivity, which lowers the response of the detector. The fabrication of these membranes also requires rather advanced processing techniques and equipment. SU-8 is an epoxy based photoresist, which has low thermal conductivity and requires only standard photolithography. A new application of SU-8 as a self-supported membrane in a thermal detector is presented. This application is demonstrated by the fabrication and characterization of both an infrared sensitive thermopile and a bolometer detector. The bolometer consists of nickel resistances connected in a Wheatstone bridge configuration, whereas the thermopile uses serially interconnected Ti/Ni thermocouple junctions. The position sensitive detectors include the lateral effect photodiodes and the quadrant detectors. Typical applications for these detectors are distance measurements and as centering devices. In the quadrant detectors, the active region consists of four pn-junctions separated by a narrow gap. The size of the active region in these detectors depends on the size of the light spot. In outdoor application, this spot size dependence degrades the performance of the four-quadrant detectors. In this thesis, a modified four-quadrant detector having the pn-junctions separated by a larger distance has been fabricated and characterized. By separating the pn-junctions the horizontal electric filed in the active region is removed, making the detector spot size insensitive. Linearity of the lateral effect photodiodes depends on the uniformity of the resistive layer in the active region. The introduction of mechanical stress in an LPSD results in a resistance change mainly due to resistivity changes, and this affects the linearity of the detector. Measurements and simulations, where mechanical stress is applied to LPSDs are presented, and support this conclusion.
|
20 |
Pressure Sensitive Paint Suitable to High Knudsen Number RegimeMori, Hideo, Niimi, Tomohide, Hirako, Madoka, Uenishi, Hiroyuki January 2006 (has links)
No description available.
|
Page generated in 0.039 seconds