Contamination study

The time dependence of the angular reflectance from molecularly contaminated optical surfaces in the Vacuum Ultraviolet (VUV) is measured. The light scattering measurements are accomplished in situ on optical surfaces in real time during deposition of molecular contaminants. The measurements are taken using non-coherent VUV sources with the predominant wavelengths being the Krypton resonance lines at 1236 and 1600 A. Detection of the scattered light is accomplished using a set of three solar blind VUV photomultipliers. An in-plane VUV BRDF (Bidirectional Reflectance Distribution Functions) experiment is described and details of the ongoing program to characterize optical materials exposed to the space environment is reported

Submission for Koronivia joint work on agriculture (KJWA) on topics 2(b) and 2(c) for SBI/SBSTA 50

Background At this Koronivia joint work on agriculture (KJWA) in-session workshop in Bonn (SBI/SBSTA 50), adaptation, adaptation co-benefits and resilience (2(b)), as well as the role of soils and integrated agricultural systems in particular (2(c)), will be at the centre of discussions. This submission provides first insights on these topics based on an ongoing scientific review of the empirical evidence for agroecology to tackle climate change in agriculture. The rationale for this review is the need for increased evidence on agroecology’s potential to build resilience to climate change. Its objective is therefore to assess the state of scientific knowledge on this question. Agroecological agricultural systems, for short, are characterised by following and combining priciples such as closed nutrient cycles, increasing soil fertility and diversity as well as building on natural ecosystem processes and services (e.g. for plant protection). Some examples of agroecological practices are organic fertilisers (compost), biological nitrogen fixation, crop rotations, cover crops, agroforestry, or mixed crop and livestock farms. Agroecology also emphasizes social aspects, focusing on e.g. equity issues, collaborative development, farmers to farmers research and education, and bottom-up organisations of value chains. The still ongoing review is conducted in a collaborative effort by Biovision Foundation for ecological development, the Research Institute of Organic Agriculture FiBL and the Food and Agriculture Organization of the United Nations FAO. It is based on an encompassing compilation of peer-reviewed literature published in English (number of studies identified: 193), Spanish (23), French (35), Portuguese (3) and Italian (4). The requirement for comparative studies, i.e. to provide data on both agroecological and some baseline farming system restricted the available studies considerably. This review is complemented with results from meta-analyses on the performance of specific agro-ecological practices and related approaches, such as conservation tillage, permaculture, organic agriculture or silvopastoral systems. The full review is planned to be be published for COP25

Formation of Actin Networks in Microfluidic Concentration Gradients

The physical properties of cytoskeletal networks are contributors in a number of mechanical responses of cells, including cellular deformation and locomotion, and are crucial for the proper action of living cells. Local chemical gradients modulate cytoskeletal functionality including the interactions of the cytoskeleton with other cellular components. Actin is a major constituent of the cytoskeleton. Introducing a microfluidic-based platform, we explored the impact of concentration gradients on the formation and structural properties of actin networks. Microfluidic-controlled flow-free and steady-state experimental conditions allow for the generation of chemical gradients of different profiles, such as linear or step-like. We discovered specific features of actin networks emerging in defined gradients. In particular, we analyzed the effects of spatial conditions on network properties, bending rigidities of network links, and the network elasticity

Integration of AI-2 Based Cell-Cell Signaling with Metabolic Cues in Escherichia coli

Citation: Mitra, A., Herren, C. D., Patel, I. R., Coleman, A., & Mukhopadhyay, S. (2016). Integration of AI-2 Based Cell-Cell Signaling with Metabolic Cues in Escherichia coli. Plos One, 11(6), 19. doi:10.1371/journal.pone.0157532The quorum sensing molecule Autoinducer-2 (AI-2) is generated as a byproduct of activated methyl cycle by the action of LuxS in Escherichia coli. AI-2 is synthesized, released and later internalized in a cell-density dependent manner. Here, by mutational analysis of the genes, uvrY and csrA, we describe a regulatory circuit of accumulation and uptake of AI-2. We constructed a single-copy chromosomal luxS-lacZ fusion in a luxS (+) merodiploid strain and evaluated its relative expression in uvrY and csrA mutants. At the entry of stationary phase, the expression of the fusion and AI-2 accumulation was positively regulated by uvrY and negatively regulated by csrA respectively. A deletion of csrA altered message stability of the luxS transcript and CsrA protein exhibited weak binding to 5' luxS regulatory region. DNA protein interaction and chromatin immunoprecipitation analysis confirmed direct interaction of UvrY with the luxS promoter. Additionally, reduced expression of the fusion in hfq deletion mutant suggested involvement of small RNA interactions in luxS regulation. In contrast, the expression of lsrA operon involved in AI-2 uptake, is negatively regulated by uvrY and positively by csrA in a cell-density dependent manner. The dual role of csrA in AI-2 synthesis and uptake suggested a regulatory crosstalk of cell signaling with carbon regulation in Escherichia coli. We found that the cAMP-CRP mediated catabolite repression of luxS expression was uvrY dependent. This study suggests that luxS expression is complex and regulated at the level of transcription and translation. The multifactorial regulation supports the notion that cell-cell communication requires interaction and integration of multiple metabolic signals

Vacuum Strength of Two Candidate Glasses for a Space Observatory

The strengths of two candidate glass types for use in a space observatory were measured. Samples of ultra-low expansion glass (ULE) and borosilicate (Pyrex) were tested in air and in vacuum at room temperature (20 C) and in vacuum after being heated to 200 C. Both glasses tested in vacuum showed an increase in strength over those tested in air. However, there was no statistical difference between the strength of samples tested in vacuum at room temperature and those tested in vacuum after heating to 200 C

Vacuum Strength of Two Candidate Glasses for a Space Observatory

The strengths of two candidate glass types for use in a space observatory were measured. Samples of ultra-low expansion glass (ULE) and borosilicate (Pyrex) were tested in air and in vacuum at room temperature (20 degrees C) and in vacuum after being heated to 200 degrees C. Both glasses tested in vacuum showed a significant increase in strength over those tested in air. However, there was no statistical difference between the strength of samples tested in vacuum at room temperature and those tested in vacuum after heating to 200 degrees C