Ladar/radar dual mode operation system for enhancing tracking range and accuracy

Previously investigated LADAR Cooperative target acquisition and tracking systems, are enhanced from 10 to 40 km in good visibility conditions. The choice of an optimal LADAR source and the ranges improvements of accurate tracking operation are described. For enhancing detection ranges, specific dual mode LADAR/RADAR systems have been proposed. The optimal solutions for all weather ranges above 400 km are L band RADAR characterized by very high power complex transmitters and bulky antennas.     

An investigation of the desensitizing effects by high power HFbroadcast transmitters on HF airborne receivers

The actual increase in power and number of high-frequency (HF) broadcasting transmitters (Tx) may strongly interfere with collocated (and even remote) radio receivers (Rx) over broad frequency ranges. The most vulnerable to harmful desensitization interference effects are airborne HF Rx flying in the proximity to the HF broadcasting Tx. In these cases extensive analysis and computational developments are essential to assess the feasibility of reliable operation of HF radio communication links. A general semi-empirical computational method is developed for quantifying the dominant mutual interference desensitization effects on a victim Rx followed by the investigation of a specific modern HF Rx used for communication with aircraft. Realistic worst-case scenarios of the airborne HF victim Rx are developed     

Effects of systemic, intracerebral, or intrathecal administration on an N-methyl-D-aspartate receptor antagonist on associative morphine analgesic tolerance and hyperalgesia in rats.

A flavor paired with morphine shifted to the right the function relating morphine dose to tail-flick latencies and provoked hyperalgesic responses when rats were tested in the absence of morphine. These learned increases in nociceptive sensitivity were not mediated by alterations in tail-skin temperature. Microinjection of the competitive N-methyl-D-aspartate (NMDA) receptor antagonist D,L-2-amino-5-phosphonopentanoic acid (AP-5) into the lateral ventricle reversed the hyperalgesic responses but spared the tolerance to morphine analgesia. By contrast, systemic administration of the noncompetitive NMDA receptor antagonist MK-801 or intrathecal infusion of AP-5 reversed the hyperalgesic responses as well as the tolerance to morphine analgesia. The results demonstrate that associatively mediated tolerance to morphine analgesia can co-occur with hyperalgesic responses and are discussed relative to learned activation of endogenous pronociceptive mechanisms. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The role of prefrontal cortex in predictive fear learning.

Pavlovian fear conditioning depends on prediction error, or the discrepancy between actual and expected outcomes. We used immunohistochemistry, neuronal tract tracing, and reversible inactivation to study the role of prefrontal cortex and thalamocortical pathways in predictive fear learning. Unexpected, but not expected, conditioned stimulus (CS)–unconditioned stimulus (US) presentations caused increased c-Fos expression in the prefrontal cortex (PFC), midline thalamus, lateral amygdala, as well as retrograde labeled midline thalamic afferents to PFC. Reversible inactivation of dorsomedial PFC, but not infralimbic PFC, prevented the associative blocking of fear learning. These results suggest a role for dorsomedial PFC (dmPFC), and a thalamic → dmPFC pathway, in signaling whether or not aversive events are expected or unexpected and so whether they are to be learned about. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Unblocking in Pavlovian fear conditioning.

Six experiments used rats to study blocking and unblocking of fear learning. An excitatory stimulus (A) blocked fear learning to a neutral stimulus (B). Unblocking of B occurred if the AB compound signaled an increase in unconditioned stimulus (US) intensity or number. Assessments of associative change during blocking showed that more was learned about B than A. Such assessments during unblocking revealed that more was learned about B than A following an increase in US intensity but not US number. These US manipulations had no differential effects on single-cue learning. The results show that variations in US intensity or number produce unblocking of fear learning, but for each there is a different profile of associative change and a potentially different mechanism. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Blocking, Unblocking, and Overexpectation of Fear: A Role for Opioid Receptors in the Regulation of Pavlovian Association Formation.

Injection of the opioid receptor antagonist naloxone facilitated acquisition of fear to contextual and auditory conditioned stimuli (CSs) in Experiments 1A and 1B. Experiment 2 showed that prior conditioning to a distinctive context blocked conditioning to an auditory CS. Blocking of CS fear was prevented by administrations of naloxone or increases in footshock intensity. Blocking of CS fear was facilitated by decreases in footshock intensity in a naloxone-reversible manner. Experiment 3 showed that compound conditioning of two CSs, each previously and separately paired with shock, produced overexpectation of fear that was reversed by naloxone. These results are consistent with a role for opioid receptors controlling Pavlovian association formation by regulating the discrepancy (A--ΣV) described by R. A. Rescorla and A. R. Wagner (1972). (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Improved computation method for radio systems single-tone spuriousprohibited frequencies list

For reliability purposes, a realistic computation method that presents, for each desired receiver channel, a list of single-tone spurious (STS) prohibited frequencies is useful. A previously developed STS computation method is significantly improved by applying the results of comparing the former computer-based prohibited values with the measured values based on two UHF receiver engineering models. The new approach incorporates a correction factor for the nonlinear amplitude-dependent effects from the receiver frequency converter stages. A more realistic STS prohibited list that includes accurate values for the system receiver rejection ratio is obtained. It helps to improve radio interference immunity from the initial stages of radio system design and to optimize the frequency allocation management policy     

The role of context in re-acquisition of extinguished alcoholic beer-seeking.

We studied the role of context in reacquisition of extinguished reward-seeking. Rats were trained to respond for alcoholic beer, then extinguished and retrained. Reacquisition was faster than acquisition regardless of whether retraining occurred in the original training context, the extinction context, a novel context, or a context with a mixed history of reinforcement. Reacquisition was also rapid after extended extinction training. Nonetheless, context did significantly influence reacquisition via affecting latency to first response: rats took significantly longer to initiate responding when tested in the extinction context. These results suggest that reacquisition of drug and reward seeking is determined by an inhibitory influence caused by the extinction context and a facilitatory influence caused by reintroduction of the reinforcer (Bouton, 1993). (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Method of interpolation factorization (MIF) for the solution oftwo-dimensional diffraction problems

A method for the exact solution of two-dimensional diffraction problems is presented. The method allows the problems to be solved practically in closed form and all the required calculations to be realized using small computers only. Among the most interesting diffraction problems solved by this method are: a thick semi-insulating plate, an infinite periodic corrugated structure, and an echelett