Promotion of structural plasticity in area V2 of visual cortex prevents against object recognition memory deficits in aging and Alzheimer's disease rodents

Memory deficit,which is often associated with aging and many psychiatric,neurological,and neurodegenerative diseases,has been a challenging issue for treatment.Up till now,all potential drug candidates have failed to produce satisfa ctory effects.Therefore,in the search for a solution,we found that a treatment with the gene corresponding to the RGS14414protein in visual area V2,a brain area connected with brain circuits of the ventral stream and the medial temporal lobe,which is crucial for object recognition memory(ORM),can induce enhancement of ORM.In this study,we demonstrated that the same treatment with RGS14414in visual area V2,which is relatively unaffected in neurodegenerative diseases such as Alzheimer s disease,produced longlasting enhancement of ORM in young animals and prevent ORM deficits in rodent models of aging and Alzheimer’s disease.Furthermore,we found that the prevention of memory deficits was mediated through the upregulation of neuronal arbo rization and spine density,as well as an increase in brain-derived neurotrophic factor(BDNF).A knockdown of BDNF gene in RGS14414-treated aging rats and Alzheimer s disease model mice caused complete loss in the upregulation of neuronal structural plasticity and in the prevention of ORM deficits.These findings suggest that BDNF-mediated neuronal structural plasticity in area V2 is crucial in the prevention of memory deficits in RGS14414-treated rodent models of aging and Alzheimer’s disease.Therefore,our findings of RGS14414gene-mediated activation of neuronal circuits in visual area V2 have therapeutic relevance in the treatment of memory deficits.

Robust stability characterizations of active metamaterials with non-Foster loads

Active metamaterials incorporating with non-Foster elements have been considered as one of the means of overcoming inherent limitations of the passive counterparts, thus achieving broadband or gain metamaterials. However, realistic active metamaterials, especially non-Foster loaded medium, would face the challenge of the possibility of instability. Moreover,they normally appear to be time-variant and in unsteady states, which leads to the necessity of a stability method to cope with the stability issue considering the system model uncertainty. In this paper, we propose an immittance-based stability method to design a non-Foster loaded metamaterial ensuring robust stability. First, the principle of this stability method is introduced after comparing different stability criteria. Based on the equivalent system model, the stability characterization is used to give the design specifications to achieve an active metamaterial with robust stability. Finally, it is applied to the practical design of active metamaterial with non-Foster loaded loop arrays. By introducing the disturbance into the nonFoster circuit（NFC）, the worst-case model uncertainty is considered during the design, and the reliability of our proposed method is verified. This method can also be applied to other realistic design of active metamaterials.

Switchable Electromagnetic Absorber/Reflectors Using Back-Loaded Active Radio Frequency Circuits

In this paper,three switchable electromagnetic absorbers/reflectors using back-loaded active radio frequency circuits are presented.In the first design,the incident waves are received by an antenna array,transmitted to the back-loaded active circuits and then reflected into the free space when the PIN diode in series in the circuit is off.When the diode is on,the incident waves can be absorbed by a matching load.In the second design,the phase of the reflected waves in the unit cell can be manipulated by adjusting the length of the microstrip lines,allowing the reflection polarization to be tuned.In the third design,by integrating RF switching chips into the back-loaded circuits,a switchable absorber/reflector with a switching polarization state is presented.The first design is fabricated and measured.The profile of the switchable absorber/reflector is approximately 0.14.A total of 2 PIN diodes are used per unit cell for both TE and TM polarizations.By using active circuits,flat in-band reflection performance and stable absorption performance can be achieved in the frequency band of 7 to 18.5 GHz(FBW of 90%)for normal incidence,and an angular stability of 45°for TE and TM polarizations is realized.

Active quenching circuit for a InGaAs single-photon avalanche diode

We present a novel gated operation active quenching circuit （AQC）. In order to simulate the quenching circuit a complete SPICE model of a InGaAs SPAD is set up according to the I-V characteristic measurement resuits of the detector. The circuit integrated with a ROIC （readout integrated circuit） is fabricated in an CSMC 0.5 μm CMOS process and then hybrid packed with the detector. Chip measurement results show that the functionality of the circuit is correct and the performance is suitable for practical system applications.