Paraquat, MPTP, and rotenone reproduce features of Parkinson's disease (PD) in experimental animals. The exact mechanisms by which these compounds damage the dopamine system are not firmly established, but selective damage to dopamine neurons and inhibition of complex I are thought to be involved. We and others have previously documented that the toxic metabolite of MPTP, MPP+, is transported into dopamine neurons through the dopamine transporter (DAT), while rotenone is not transported by DAT. We have also demonstrated the requirement for complex I inhibition and oxidative damage in the dopaminergic neurodegeneration produced by rotenone. Based on structural similarity to MPP+, it has been proposed that paraquat exerts selective dopaminergic toxicity through transport by the DAT and subsequent inhibition of mitochondrial complex I. In this study we report that paraquat is neither a substrate nor inhibitor of DAT. We also demonstrate that in vivo exposure to MPTP and rotenone, but not paraquat, inhibits binding of 3H-dihydrorotenone to complex I in brain mitochondria. Rotenone and MPP+ were both effective inhibitors of complex I activity in isolated brain mitochondria, while paraquat exhibited weak inhibitory effects only at millimolar concentrations. These data indicate that, despite the apparent structural similarity to MPP+, paraquat exerts its deleterious effects on dopamine neurons in a manner that is unique from rotenone and MPTP.
Although synaptic behaviours of memristors have been widely demonstrated, implementation of an even simple artificial neural network is still a great challenge. In this work, we demonstrate the associative memory on the basis of a memristive Hopfield network. Different patterns can be stored into the memristive Hopfield network by tuning the resistance of the memristors, and the pre-stored patterns can be successfully retrieved directly or through some associative intermediate states, being analogous to the associative memory behaviour. Both single-associative memory and multi-associative memories can be realized with the memristive Hopfield network.
We study the paired-pulse-induced response of a NiO x -based memristor. The behavior of the memristor is surprisingly similar to the paired-pulse facilitation of a biological synapse. When the memristor is stimulated with a pair of electrical pulses, the current of the memristor induced by the second pulse is larger than that by the first pulse. In addition, the magnitude of the facilitation decreases with the pulse interval, while it increases with the pulse magnitude or pulse width.
Aims
Determine whether 18 months of telephone continuing care improves 24 month outcomes for patients with alcohol dependence. Subgroup analyses were done to identify patients who would most benefit from continuing care.
Design
Comparative effectiveness trial of continuing care that consisted of monitoring and feedback only (TM) or monitoring and feedback plus counseling (TMC). Patients were randomized to treatment as usual (TAU), TAU plus TM, or TAU plus TMC, and followed quarterly for 24 months.
Setting
Publicly funded intensive outpatient programs (IOP)
Participants
252 alcohol dependent patients (49% with current cocaine dependence) who completed 3 weeks of IOP.
Measurements
Percent days drinking, any heavy drinking, and a composite good clinical outcome.
Findings
In the intent to treat sample, group differences in alcohol outcomes out to 18 months favoring TMC over TAU were no longer present in months 19–24. Approximately 50% of participants met criteria for Good Clinical Outcomes throughout treatment and follow-up with a non-significant trend for TMC to perform better than usual care. Overall significant effects favoring TMC and TM over TAU were seen for women; and TMC was also superior to TAU for participants with social support for drinking, low readiness to change, and prior alcohol treatments. Most of these effects were obtained on at least 2 of 3 outcomes. However, no effects remained significant at 24 months.
Conclusions
The benefits of an extended telephone-based continuing care programme to treat alcohol dependence did not persist after the end of the intervention. A post-hoc analysis suggested that women and individuals with social support for drinking, low readiness to change, or prior alcohol treatments may benefit from the intervention.
Zn2SnO4 nanowires and Zn2SnO4 diameter-modulated (DM) nanowires were successfully synthesized,
accompanied by the formation of ZnO nanowires, via the thermal evaporation
of a mixture of ZnO and SnO2
powders, using gold as a catalyst. Their morphologies and structures
were characterized by scanning electron
microscopy, X-ray spectroscopy, and high-resolution transmission electron
microscopy. The ZnO nanowires
were single crystalline, with an axis of [011̄0], which is different
from the conventional [0001] orientation
and might be determined by the vapor components involved in the reaction.
Zn2SnO4 nanowires and Zn2SnO4 DM nanowires were single crystalline, with [302] and [111]
growth directions, respectively. A vapor−liquid−solid
(VLS) growth mechanism is proposed, to interpret the growth of nanowires
in the experiment.
In regard to the formation of Zn2SnO4 DM nanowires,
we suggest that the disturbance of vapor concentration
is a major factor that changes the size of the catalyst alloy droplets
and the growth velocity of nanowires, and
ultimately results in the diameter-modulated feature.
The well-known Ebbinghaus forgetting curve, which describes how information is forgotten over time, can be emulated using a NiO-based memristor with conductance that decreases with time after the application of electrical pulses. Here, the conductance is analogous to the memory state, while each electrical pulse represents a memory stimulation or learning event. The decrease in the conductance with time depends on the stimulation parameters, including pulse height and width and the number of pulses, which emulates memory loss behavior well in that the time taken for the memory to be lost depends on how the information is learned.
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