506 research outputs found
Extinction with varenicline and nornicotine, but not ABT-418, weakens conditioned responding evoked by the interoceptive stimulus effects of nicotine
The interoceptive stimulus effects of nicotine acquire control over behavior. This observation, among others, suggests that the stimulus effects of nicotine are important in the development and tenacity of tobacco dependence. Despite this importance, there has been little research examining whether non-reinforced presentations (extinction) of a ligand that share stimulus effects of nicotine will weaken responding controlled by nicotine. Rats were trained to discriminate nicotine (0.4 mg/kg) from saline using a discriminated goal-tracking task in which nicotine signaled intermittent access to sucrose; sucrose was withheld on saline sessions. Experiment 1 examined substitution for nicotine by ABT-418, nornicotine, epibatidine, varenicline, or cytisine in 4-min extinction tests. Experiments 2 to 5 [low dose nicotine (0.05 mg/kg), ABT-418, nornicotine, or varenicline, respectively] examined whether substitution for nicotine would persist if extinction tests were increased to 20 min and repeated daily for 6 days. Finally, generalization of this extinction back to the nicotine training stimulus was assessed. Full substitution in brief 4-min extinction tests was seen for ABT-418, nornicotine, epibatidine, varenicline, and cytisine. Low-dose nicotine, ABT-418, nornicotine, and varenicline, evoked only a partial ‘nicotine-like’ response in the first 20-min extinction test. With repeated extinction, only low-dose nicotine, nornicotine, and varenicline continued to substitute. Extinction with nornicotine and varenicline transferred back to nicotine as indicated by a partial conditioned response to the training stimulus. Interpretations regarding ‘nicotine-like’ effects of a ligand depend on the nature of the test. Understanding the processes mediating transfer of extinction learning with potential pharmacotherapies may reveal new treatment targets
Extinction with varenicline and nornicotine, but not ABT-418, weakens conditioned responding evoked by the interoceptive stimulus effects of nicotine
The interoceptive stimulus effects of nicotine acquire control over behavior. This observation, among others, suggests that the stimulus effects of nicotine are important in the development and tenacity of tobacco dependence. Despite this importance, there has been little research examining whether non-reinforced presentations (extinction) of a ligand that share stimulus effects of nicotine will weaken responding controlled by nicotine. Rats were trained to discriminate nicotine (0.4 mg/kg) from saline using a discriminated goal-tracking task in which nicotine signaled intermittent access to sucrose; sucrose was withheld on saline sessions. Experiment 1 examined substitution for nicotine by ABT-418, nornicotine, epibatidine, varenicline, or cytisine in 4-min extinction tests. Experiments 2 to 5 [low dose nicotine (0.05 mg/kg), ABT-418, nornicotine, or varenicline, respectively] examined whether substitution for nicotine would persist if extinction tests were increased to 20 min and repeated daily for 6 days. Finally, generalization of this extinction back to the nicotine training stimulus was assessed. Full substitution in brief 4-min extinction tests was seen for ABT-418, nornicotine, epibatidine, varenicline, and cytisine. Low-dose nicotine, ABT-418, nornicotine, and varenicline, evoked only a partial ‘nicotine-like’ response in the first 20-min extinction test. With repeated extinction, only low-dose nicotine, nornicotine, and varenicline continued to substitute. Extinction with nornicotine and varenicline transferred back to nicotine as indicated by a partial conditioned response to the training stimulus. Interpretations regarding ‘nicotine-like’ effects of a ligand depend on the nature of the test. Understanding the processes mediating transfer of extinction learning with potential pharmacotherapies may reveal new treatment targets
Prospectus, August 28, 1989
https://spark.parkland.edu/prospectus_1989/1017/thumbnail.jp
Prospectus, March 29, 1990
https://spark.parkland.edu/prospectus_1990/1009/thumbnail.jp
Local-Oscillator Noise Coupling in Balanced Homodyne Readout for Advanced Gravitational Wave Detectors
The second generation of interferometric gravitational wave detectors are
quickly approaching their design sensitivity. For the first time these
detectors will become limited by quantum back-action noise. Several back-action
evasion techniques have been proposed to further increase the detector
sensitivity. Since most proposals rely on a flexible readout of the full
amplitude- and phase-quadrature space of the output light field, balanced
homodyne detection is generally expected to replace the currently used DC
readout. Up to now, little investigation has been undertaken into how balanced
homodyne detection can be successfully transferred from its ubiquitous
application in table-top quantum optics experiments to large-scale
interferometers with suspended optics. Here we derive implementation
requirements with respect to local oscillator noise couplings and highlight
potential issues with the example of the Glasgow Sagnac Speed Meter experiment,
as well as for a future upgrade to the Advanced LIGO detectors.Comment: 7 pages, 5 figure
Prospectus, November 8, 1989
https://spark.parkland.edu/prospectus_1989/1027/thumbnail.jp
Effects of static and dynamic higher-order optical modes in balanced homodyne readout for future gravitational waves detectors
With the recent detection of Gravitational waves (GW), marking the start of the new field of GW astronomy, the push for building more sensitive laser-interferometric gravitational wave detectors (GWD) has never been stronger. Balanced homodyne detection (BHD) allows for a quantum noise (QN) limited readout of arbitrary light field quadratures, and has therefore been suggested as a vital building block for upgrades to Advanced LIGO and third generation observatories. In terms of the practical implementation of BHD, we develop a full framework for analyzing the static optical high order modes (HOMs) occurring in the BHD paths related to the misalignment or mode matching at the input and output ports of the laser interferometer. We find the effects of HOMs on the quantum noise limited sensitivity is independent of the actual interferometer configuration, e.g. Michelson and Sagnac interferometers are effected in the same way. We show that misalignment of the output ports of the interferometer (output misalignment) only effects the high frequency part of the quantum noise limited sensitivity (detection noise). However, at low frequencies, HOMs reduce the interferometer response and the radiation pressure noise (back action noise) by the same amount and hence the quantum noise limited sensitivity is not negatively effected in that frequency range. We show that the misalignment of laser into the interferometer (input misalignment) produces the same effect as output misalignment and additionally decreases the power inside the interferometer. We also analyze dynamic HOM effects, such as beam jitter created by the suspended mirrors of the BHD. Our analyses can be directly applied to any BHD implementation in a future GWD. Moreover, we apply our analytical techniques to the example of the speed meter proof of concept experiment under construction in Glasgow. We find that for our experimental parameters, the performance of our seismic isolation system in the BHD paths is compatible with the design sensitivity of the experiment
Prospectus, October 11, 1989
https://spark.parkland.edu/prospectus_1989/1023/thumbnail.jp
Demonstration of a switchable damping system to allow low-noise operation of high-Q low-mass suspension systems
Low mass suspension systems with high-Q pendulum stages are used to enable
quantum radiation pressure noise limited experiments. Utilising multiple
pendulum stages with vertical blade springs and materials with high quality
factors provides attenuation of seismic and thermal noise, however damping of
these high-Q pendulum systems in multiple degrees of freedom is essential for
practical implementation. Viscous damping such as eddy-current damping can be
employed but introduces displacement noise from force noise due to thermal
fluctuations in the damping system. In this paper we demonstrate a passive
damping system with adjustable damping strength as a solution for this problem
that can be used for low mass suspension systems without adding additional
displacement noise in science mode. We show a reduction of the damping factor
by a factor of 8 on a test suspension and provide a general optimisation for
this system.Comment: 5 pages, 5 figure
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