Silicon photonics devices for integrated analog signal processing and sampling

Silicon photonics offers the possibility of a reduction in size weight and power for many optical systems, and could open up the ability to build optical systems with complexities that would otherwise be impossible to achieve. Silicon photonics is an emerging technology that has already been inserted into commercial communication products. This technology has also been applied to analog signal processing applications. MIT Lincoln Laboratory in collaboration with groups at MIT has developed a toolkit of silicon photonic devices with a focus on the needs of analog systems. This toolkit includes low-loss waveguides, a high-speed modulator, ring resonator based filter bank, and all-silicon photodiodes. The components are integrated together for a hybrid photonic and electronic analog-to-digital converter. The development and performance of these devices will be discussed. Additionally, the linear performance of these devices, which is important for analog systems, is also investigated

VEGF-A and Semaphorin3A: Modulators of vascular sympathetic innervation

AbstractSympathetic nerve activity regulates blood pressure by altering peripheral vascular resistance. Variations in vascular sympathetic innervation suggest that vascular-derived cues promote selective innervation of particular vessels during development. As axons extend towards peripheral targets, they migrate along arterial networks following gradients of guidance cues. Collective ratios of these gradients may determine whether axons grow towards and innervate vessels or continue past non-innervated vessels towards peripheral targets. Utilizing directed neurite outgrowth in a three-dimensional (3D) co-culture, we observed increased axon growth from superior cervical ganglion explants (SCG) towards innervated compared to non-innervated vessels, mediated in part by vascular endothelial growth factor (VEGF-A) and Semaphorin3A (Sema3A) which both signal via neuropilin-1 (Nrp1). Exogenous VEGF-A, delivered by high-expressing VEGF-A–LacZ vessels or by rhVEGF-A/alginate spheres, increased sympathetic neurite outgrowth while exogenous rhSema3A/Fc decreased neurite outgrowth. VEGF-A expression is similar between the innervated and non-innervated vessels examined. Sema3A expression is higher in non-innervated vessels. Spatial gradients of Sema3A and VEGF-A may promote differential Nrp1 binding. Vessels expressing high levels of Sema3A favor Nrp1-PlexinA1 signaling, producing chemorepulsive cues limiting sympathetic neurite outgrowth and vascular innervation; while low Sema3A expressing vessels favor Nrp1-VEGFR2 signaling providing chemoattractive cues for sympathetic neurite outgrowth and vascular innervation

Animal Housing—Dietary Manipulation Overview

This fact sheet features diet manipulation as a management practice to address odor and emissions coming from animal housing and manure storage systems. Reducing nutrients in manure can lead to reductions in emissions. Reducing nutrients in manure is broken into two main areas, nutrient input reduction and nutrient form modification. This fact sheet describes both methods.This fact sheet is part of the Air Management Practices Assessment Tool (AMPAT) developed at Iowa State University and funded by the National Pork Board. Additional resources can be found on the AMPAT web page at: www.agronext.iastate.edu/ampathttps://lib.dr.iastate.edu/extension_ag_pubs/1210/thumbnail.jp

Animal Housing—Barriers Overview

Barriers can be used to address dust and odor coming from animal housing. Barriers, or “windbreak walls” are used downwind of fans to reduce forward momentum of airflow, settle out dust particles, and push the exiting plume higher into the atmosphere.https://lib.dr.iastate.edu/extension_ag_pubs/1207/thumbnail.jp