The influence of opioid antagonists and of morphine on rat hippocampal slices in a model of reversible hypoxia/hypoglycemia was investigated by assessment of evoked field potentials (population spike ...amplitude). In control slices, a brief hypoxia/hypoglycemia led to a loss of field potentials followed by an impaired recovery (40–50% of baseline) during reperfusion. In contrast, restoration was significantly improved when the opioid receptor antagonists funaltrexamine (μ) or naltrindole (δ) were administered prior to and during hypoxia/hypoglycemia. In addition, recovery was improved in brain slices derived from μ-opioid receptor-deficient mice as compared to wild-type mice, indicating a deleterious role of endogenous opioids in hypoxia/hypoglycemia.
Exogenous opiate exposure with morphine (0.1, 1.0, 10
μM) prior to hypoxia/hypoglycemia caused a slight concentration dependent increase of evoked field potentials. When morphine exposure was terminated after 1
h and immediately followed by hypoxia/hypoglycemia, an impaired recovery of population spike amplitude was obtained, dependent on morphine concentration during preincubation. These results demonstrate that morphine aggravates neurotoxic effects of hypoxia/hypoglycemia.
Conversely, when onset of hypoxia/hypoglycemia was delayed for 3
h after morphine termination, a significantly improved recovery was observed. Similarly, in vivo administration of morphine 12
h prior to slice preparation resulted in a dose dependent improved recovery of field potentials after hypoxia/hypoglycemia. These results provide evidence that preconditioning with morphine is able to induce neuroprotective effects.
Congress, for example, enacted the Automobile Dealers' Day in Court Act in 1956 to (1) shift at least some power in the manufacturer-dealer relationship in favor of the dealers and (2) override ...dealership agreement provisions inhibiting a "judicial determination" of whether the manufacturer acted in good faith.11 States have a significant interest in the protection of new automobile dealerships, which generate nearly 18 percent of all sales tax revenue, from overreaching and abuse by manufacturers.12 Today, a literal patchwork of laws enacted by all fifty states regulates, if not mandates, the automobile franchised dealer relationship. Tesla's direct sales model is just one potential threat of many, but if defensive efforts are concentrated on extending market dominance through legislation, dealers may be caught flat-footed when those measures prove unsuccessful-just as the taxi industry's longtime reliance on government regulation created massive inroads for alternatives.101 The legislation of dealer franchises as the exclusive source of new vehicles is nothing more than an anti-competitive mandate powered by lobbying and political pressures, producing results that are the antithesis of the democratic, free market system.
Studies dealing with the bonding behavior of silicon wafers coated with thermal oxide, plasma-enhanced chemical vapor deposition (PE-CVD) oxide, PE-CVD oxynitride, PE-CVD nitride and low-pressure ...(LP) CVD nitride are presented. The PE-CVD layers require a chemo-mechanical polishing (CMP) before bonding to reduce the surface roughness. The bonding energies of the wafer pairs with different interface layers are similar to those of bonded hydrophilic silicon wafers. Infrared microscopy of patterned wafer pairs reveals interfaces which are almost free of bubbles. Presumably, the gas, which usually generates such interface bubbles, diffuses into the interface cavities. The tensile strengths of patterned wafer pairs including a PE-CVD oxide or a PE-CVD oxynitride interface layer are about twice as high as for patterned hydrophilic silicon wafer pairs.
Abstract Background: In rat hippocampal slices, a short hypoxia/hypoglycemia causes immediate loss of evoked potentials (population spike amplitude) in the CA1 region and the extent of ...electrophysiological restoration during reperfusion can serve as a parameter for cell function. Previous experiments using this model revealed that exposure to morphine aggravates the neurotoxic effects of a subsequent hypoxia/hypoglycemia in a concentration-dependent manner. Therefore, the aim of the present study was to evaluate the effects of additional mu-opioid receptor (MOPr) agonists on the electrophysiological restoration after hypoxia/hypoglycemia. Methods: Rat hippocampal slices were exposed to either morphine (10 μM), pethidine (10 μM), fentanyl (100 nM/1 μM) or to the synthetic peptide d -Ala2 , N -Me-Phe4 , Glycinol5 -enkephalin (DAMGO, 10 μM) for 60 min; thereafter, slices underwent a brief hypoxic/hypoglycemic episode followed by reperfusion (drug-free) for 2.5 h. Electrophysiological recording consisted of determination of population spike amplitude in CA1 in response to constant stimulation of Schäffer's collaterals. Results: Exposure to morphine prior to hypoxia/hypoglycemia resulted in a significantly impaired electrophysiological recovery during reperfusion when compared to controls. Following exposure to pethidine, the electrophysiological recovery was slightly reduced, whereas fentanyl or DAMGO did not affect restoration of population spike amplitude during reperfusion. Conclusions: The results of the present study demonstrate that different MOPr agonists differentially influence the electrophysiological recovery of hippocampal slices following a brief hypoxia/hypoglycemia. It is speculated that known receptor-internalizing opioids such as fentanyl or DAMGO may have less neurotoxic effect in hypoxia/hypoglycemia than the non-internalizing drug morphine.
Silicon detectors for the sLHC Affolder, A.; Allport, P.P.; Bates, R. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2011, Letnik:
658, Številka:
1
Journal Article
Recenzirano
In current particle physics experiments, silicon strip detectors are widely used as part of the inner tracking layers. A foreseeable large-scale application for such detectors consists of the ...luminosity upgrade of the Large Hadron Collider (LHC), the super-LHC or sLHC, where silicon detectors with extreme radiation hardness are required. The mission statement of the CERN RD50 Collaboration is the development of radiation-hard semiconductor devices for very high luminosity colliders. As a consequence, the aim of the R&D programme presented in this article is to develop silicon particle detectors able to operate at sLHC conditions. Research has progressed in different areas, such as defect characterisation, defect engineering and full detector systems. Recent results from these areas will be presented. This includes in particular an improved understanding of the macroscopic changes of the effective doping concentration based on identification of the individual microscopic defects, results from irradiation with a mix of different particle types as expected for the sLHC, and the observation of charge multiplication effects in heavily irradiated detectors at very high bias voltages.
Radiation-hard semiconductor detectors for SuperLHC Bruzzi, M.; Alfieri, G.; Assouak, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
04/2005, Letnik:
541, Številka:
1
Journal Article
Recenzirano
An option of increasing the luminosity of the Large Hadron Collider (LHC) at CERN to 10
35
cm
−2
s
−1 has been envisaged to extend the physics reach of the machine. An efficient tracking down to a ...few centimetres from the interaction point will be required to exploit the physics potential of the upgraded LHC. As a consequence, the semiconductor detectors close to the interaction region will receive severe doses of fast hadron irradiation and the inner tracker detectors will need to survive fast hadron fluences of up to above 10
16
cm
−2. The CERN-RD50 project “Development of Radiation Hard Semiconductor Devices for Very High Luminosity Colliders” has been established in 2002 to explore detector materials and technologies that will allow to operate devices up to, or beyond, this limit.
The strategies followed by RD50 to enhance the radiation tolerance include the development of new or defect engineered detector materials (SiC, GaN, Czochralski and epitaxial silicon, oxygen enriched Float Zone silicon), the improvement of present detector designs and the understanding of the microscopic defects causing the degradation of the irradiated detectors. The latest advancements within the RD50 collaboration on radiation hard semiconductor detectors will be reviewed and discussed in this work.
Silicon detectors for the sLHC Affolder, A.; Allport, P. P.; Barber, T. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
12/2011, Letnik:
658, Številka:
1
Journal Article
The envisaged upgrade of the Large Hadron Collider (LHC) at CERN towards the Super-LHC (SLHC) with a 10 times increased luminosity of 10
35
cm
−2
s
−1 will present severe challenges for the tracking ...detectors of the SLHC experiments. Unprecedented high radiation levels and track densities and a reduced bunch crossing time in the order of 10
ns as well as the need for cost effective detectors have called for an intensive R&D program. The CERN RD50 collaboration “Development of Radiation Hard Semiconductor Devices for Very High Luminosity Colliders” is working on the development of semiconductor sensors matching the requirements of the SLHC. Sensors based on defect engineered silicon like Czochralski, epitaxial and oxygen enriched silicon have been developed. With 3D, Semi-3D and thin detectors new detector concepts have been evaluated and a study on the use of standard and oxygen enriched p-type silicon detectors revealed a promising approach for radiation tolerant cost effective devices. These and other most recent advancements of the RD50 collaboration are presented.
The proposed luminosity upgrade of the Large Hadron Collider (S-LHC) at CERN will demand the innermost layers of the vertex detectors to sustain fluences of about 10
16 hadrons/cm
2. Due to the high ...multiplicity of tracks, the required spatial resolution and the extremely harsh radiation field new detector concepts and semiconductor materials have to be explored for a possible solution of this challenge. The CERN RD50 collaboration “Development of Radiation Hard Semiconductor Devices for Very High Luminosity Colliders” has started in 2002 an R&D program for the development of detector technologies that will fulfill the requirements of the S-LHC. Different strategies are followed by RD50 to improve the radiation tolerance. These include the development of defect engineered silicon like Czochralski, epitaxial and oxygen-enriched silicon and of other semiconductor materials like SiC and GaN as well as extensive studies of the microscopic defects responsible for the degradation of irradiated sensors. Further, with 3D, Semi-3D and thin devices new detector concepts have been evaluated. These and other recent advancements of the RD50 collaboration are presented and discussed.
This study validates transcranial Doppler sonography (TCD) for determination of the lower limit of cerebral blood flow (CBF) autoregulation and establishes a relation between global CBF and mean flow ...velocity (Vmean) in the middle cerebral artery.
Relative changes in CBF and in Vmean were compared in 12 normal volunteers (2 women and 10 men; median age, 30 years range, 21 to 61 years). Catheters was placed in the left radial artery and in the bulb of the right internal jugular vein, respectively. Baseline CBF was measured by single-photon emission computed tomography scanning; concomitantly, blood samples were drawn for calculation of the cerebral arteriovenous oxygen difference. Then changes in mean arterial pressure (MAP) were induced, and relative changes in global CBF were calculated according to Fick's principle assuming a constant cerebral oxygen metabolism. MAP was increased 30 mm Hg by norepinephrine infusion and was decreased by lower body negative pressure. Vmean was measured in the right middle cerebral artery by a 2-MHz probe, and blood samples were drawn at intervals of 5 mm Hg.
MAP values between 122 (range, 110 to 140) and 48 (range, 34 to 75) mm Hg were measured. The lower limit of autoregulation (the blood pressure under which autoregulation is off) as determined by Vmean did not differ significantly from that determined by relative changes in global CBF: 91 (range, 41 to 108) and 79 (range, 53 to 113) mm Hg, respectively. A significant correlation between Vmean and relative changes in global CBF was demonstrated below the lower limit of autoregulation (R2 = .73, P < .001; CBF = -6.3 + 1.0.Vmean). Above the lower limit both values were stable.
TCD is valid for determination of the lower limit of CBF autoregulation, and changes in CBF may be reliably evaluated by TCD during changes in cerebral perfusion pressure in normal subjects.
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