Neural correlates of sensation and navigation in the retrosplenial cortex

By virtue of its anatomical connections, the retrosplenial cortex (RSC) is well suited to mediate bidirectional communication between the hippocampal formation and the neocortex. However, what information is encoded in the firing of RSC neurons is largely unclear. I used 2-photon calcium imaging to measure RSC population activity during a goal-directed virtual spatial task that was sometimes complemented by drifting gratings visual stimuli. Over 10% of RSC neurons, mainly in superficial layers, showed place fields with properties similar to CA1 place cells measured in the same task. A distinct subset of neurons (~15%), predominantly in agranular RSC, showed pronounced responses to the visual stimuli. Some of these RSC visual neurons were specifically selective for the speed and direction of visual motion. The results suggest that RSC contains multiple functional cell types distributed differentially across depths and subregions showing responses to external sensory stimulation and internal navigational signals.NERF AIHS NSER

Hippocampus-dependent emergence of spatial sequence coding in retrosplenial cortex.

Retrosplenial cortex (RSC) is involved in visuospatial integration and spatial learning, and RSC neurons exhibit discrete, place cell-like sequential activity that resembles the population code of space in hippocampus. To investigate the origins and population dynamics of this activity, we combined longitudinal cellular calcium imaging of dysgranular RSC neurons in mice with excitotoxic hippocampal lesions. We tracked the emergence and stability of RSC spatial activity over consecutive imaging sessions. Overall, spatial activity in RSC was experience-dependent, emerging gradually over time, but, as seen in the hippocampus, the spatial code changed dynamically across days. Bilateral but not unilateral hippocampal lesions impeded the development of spatial activity in RSC. Thus, the emergence of spatial activity in RSC, a major recipient of hippocampal information, depends critically on an intact hippocampus; the indirect connections between the dysgranular RSC and the hippocampus further indicate that hippocampus may exert such influences polysynaptically within neocortex

Closed-loop control of epilepsy by transcranial electrical stimulation

Many neurological and psychiatric diseases are associated with clinically detectable, altered brain dynamics. The aberrant brain activity, in principle, can be restored through electrical stimulation. In epilepsies, abnormal patterns emerge intermittently, and therefore, a closed-loop feedback brain control that leaves other aspects of brain functions unaffected is desirable. Here, we demonstrate that seizure-triggered, feedback transcranial electrical stimulation (TES) can dramatically reduce spike-and-wave episodes in a rodent model of generalized epilepsy. Closed-loop TES can be an effective clinical tool to reduce pathological brain patterns in drug-resistant patients.Fil: Berényi, Antal. Rutgers University; Estados Unidos. University of New York; Estados Unidos. University of Szeged; HungríaFil: Belluscio, Mariano Andres. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Rutgers University; Estados UnidosFil: Mao, Dun. Rutgers University; Estados UnidosFil: Buzsáki, György. Rutgers University; Estados Unidos. University of New York; Estados Unido

COVID 19:assessment of crisis management in China and the United States

The article is an exploratory study to understand the United States and Chinese governments’ response, with different governance models, to the COVID-19 pandemic. This article looks at initial responses during the crisis, how important resources were managed, and the interplay between government and civil society during the containment phase. It employs qualitative methods by drawing on primary and secondary data. The findings reveal that a top-down government structure, as exemplified by China, has provided greater leeway to respond to the crisi

COVID -19 pandemic : a litmus test of the resilience of Chinese and US governance models

The article is an exploratory study to understand the United States and Chinese governments’ response, with different governance models, to the COVID-19 pandemic. This article looks at both governments’ initial reactions during the crisis, how essential resources were managed, and the interplay between government and civil society during the containment phase. This qualitative study uses a case study method to explore the contemporary phenomenon of COVID-19. It draws on secondary data such as government and international organisation reports, newspaper articles, journal articles, and books. The findings reveal that a top-down government structure has provided greater leeway to respond to the crisis, as exemplified by China. Since this research is a preliminary study, the authors do not draw far-reaching conclusions about which model fared better in the management of the pandemic; nevertheless, the analysis notes the increased capacity of governments to act during public health crises if power and resources are concentrated, including the ability to mobilise civil actors to help with the problem. Assessing the response of the U.S. and Chinese governments significantly contributes to the literature on governance and crisis management, and thus benefits both pundits and policymakers

Spatially controlled electrostatic doping in graphene p-i-n junction for hybrid silicon photodiode

Sufficiently large depletion region for photocarrier generation and separation is a key factor for two-dimensional material optoelectronic devices, but few device configurations has been explored for a deterministic control of a space charge region area in graphene with convincing scalability. Here we investigate a graphene-silicon p-i-n photodiode defined in a foundry processed planar photonic crystal waveguide structure, achieving visible - near-infrared, zero-bias and ultrafast photodetection. Graphene is electrically contacting to the wide intrinsic region of silicon and extended to the p an n doped region, functioning as the primary photocarrier conducting channel for electronic gain. Graphene significantly improves the device speed through ultrafast out-of-plane interfacial carrier transfer and the following in-plane built-in electric field assisted carrier collection. More than 50 dB converted signal-to-noise ratio at 40 GHz has been demonstrated under zero bias voltage, with quantum efficiency could be further amplified by hot carrier gain on graphene-i Si interface and avalanche process on graphene-doped Si interface. With the device architecture fully defined by nanomanufactured substrate, this study is the first demonstration of post-fabrication-free two-dimensional material active silicon photonic devices.Comment: NPJ 2D materials and applications (2018

Cosmic Radiation Reduced Photo-Thermal Dispersion in Silicon Micro-Ring Resonators

We show post-spaceflight results for a silicon photonic integrated circuit micro-ring resonator. The free-carrier lifetime reduced by factor of 2 after radiation damage events in space

Traditional Chinese Herb Combined with Surgery versus Surgery for Varicocele Infertility: A Systematic Review and Meta-Analysis

Objective. The objective of this study was to conduct a systematic review to assess the effectiveness and safety of traditional Chinese herb combined with surgery for male varicocele infertility compared to surgery. Methods. Randomized controlled trials (RCTs) data of traditional Chinese herbs combined with surgery for male varicocele fertility versus surgery were collected by searching the Cochrane Library, Embase, PubMed, and Chinese databases. The risk of bias was assessed using Cochrane Handbook. Study outcomes were presented as risk ratios (RRs) for dichotomous data. Results. Seventeen of 72 potentially relevant trials met the inclusion criteria. The methodological qualities of the RCTs were low. Compared with the surgery group, the traditional Chinese herb combined with surgery group had superiority in pregnancy rate at 3-month (RR=1.76, and P=0.008), 6-month (RR=1.58, and P=0.0005), and 2-year (RR=1.58, and P=0.0005) follow-ups. No RCT was found to describe the side effects. Conclusion. On considering the low methodological quality of RCTs, there was no enough evidence on traditional Chinese herb with surgery for male varicocele infertility, and more high-quality RCTs of large sample sizes are required

Dynamic Covalent Synthesis of Crystalline Porous Graphitic Frameworks

Porous graphitic framework (PGF) is a two-dimensional (2D) material that has emerging energy applications. An archetype contains stacked 2D layers, the structure of which features a fully annulated aromatic skeleton with embedded heteroatoms and periodic pores. Due to the lack of a rational approach in establishing in-plane order under mild synthetic conditions, the structural integrity of PGF has remained elusive and ultimately limited its material performance. Here, we report the discovery of the unusual dynamic character of the C=N bonds in the aromatic pyrazine ring system under basic aqueous conditions, which enables the successful synthesis of a crystalline porous nitrogenous graphitic framework with remarkable in-plane order, as evidenced by powder X-ray diffraction studies and direct visualization using high-resolution transmission electron microscopy. The crystalline framework displays superior performance as a cathode material for lithium-ion batteries, outperforming the amorphous counterparts in terms of capacity and cycle stability. Insertion of well-defined, evenly spaced nanoscale pores into the two-dimensional (2D) layers of graphene invokes exciting properties due to the modulation of its electronic band gaps and surface functionalities. A bottom-up synthesis approach to such porous graphitic frameworks (PGFs) is appealing but also remains a great challenge. The current methods of building covalent organic frameworks rely on a small collection of thermodynamically reversible reactions. Such reactions are, however, inadequate in generating a fully annulated aromatic skeleton in PGFs. With the discovery of dynamic pyrazine formation, we succeeded in applying this linking chemistry to obtain a crystalline PGF material, which has displayed high electrical conductivity and remarkable performance as a cathode material for lithium-ion batteries. We envision that the demonstrated success will open the door to a wide array of fully annulated 2D porous frameworks, which hold immense potential for clean energy applications. We report the unusual dynamic characteristics of the C=N bonds in the pyrazine ring promoted under basic aqueous conditions, which enables the successful synthesis of two-dimensional porous graphitic frameworks (PGFs) featuring fully annulated aromatic skeletons and periodic pores. The PGF displayed high electrical conductivity and remarkable performance as a cathode material for lithium-ion batteries, far outperforming the amorphous counterparts in terms of capacity and cycle stability

Performance Evaluation of Silicon Mach-Zehnder Modulator after Cosmic Radiation to Enable Small Satellite Laser Communication

To evaluate the performance change of Photonic integrated circuits after real cosmic radiation, silicon Mach-Zehnder Modulators were mounted on International Space Station on Low Earth Orbit for 6 months’ radiation harshness. Measured data of the device before and after radiation showed the permanent change of the effective index (around 10-3), the reduced carrier recombination lifetime, and the extended high speed bandwidth