Continued investigation of LDEF's structural frame and thermal blankets by the Meteoroid and Debris Special Investigation Group

This report focuses on the data acquired by detailed examination of LDEF intercostals, 68 of which are now in possession of the Meteoroid and Debris Special Investigation Group (M&D SIG) at JSC. In addition, limited data will be presented for several small sections from the A0178 thermal control blankets that were examined/counted prior to being shipped to Principal Investigators (PI's) for scientific study. The data presented here are limited to measurements of crater and penetration-hole diameters and their frequency of occurrence which permits, yet also constrains, more model-dependent, interpretative efforts. Such efforts will focus on the conversion of crater and penetration-hole sizes to projectile diameters (and masses), on absolute particle fluxes, and on the distribution of particle-encounter velocities. These are all complex issues that presently cannot be pursued without making various assumptions which relate, in part, to crater-scaling relationships, and to assumed trajectories of natural and man-made particle populations in LEO that control the initial impact conditions

Current activities and results of the Long Duration Exposure Facility Meteoroid and Debris Special Investigation Group

Fiscal Year 1994 will bring to a close the initial investigative activities associated with the Long Duration Exposure Facility (LDEF). LDEF was a 14-faced spacecraft (i.e., 12-sided cylinder and two ends) which housed 54 different experimental packages in low-Earth orbit (LEO) from Apr. 1984 to Jan. 1990 (i.e., for approx. 5.75 years). Since LDEF's return, the Meteoroid & Debris Special Investigation Group (M&D SIG) has been examining various LDEF components in order to better understand and define the LEO particulate environment. Members of the M&D SIG at JSC in Houston, TX have been contributing to these studies by carefully examining and documenting all impact events found on LDEF's 6061-T6 aluminum Intercostals (i.e., one of the spacecraft's structural frame components). Unlike all other hardware on LDEF, the frame exposed significantly large surface areas of a single homogeneous material in all (i.e., 26) possible LDEF pointing directions. To date, 28 of the 68 Intercostals in the possession of the M&D SIG have been documented. This data, as well as similar information from various LDEF investigators, can be accessed through the M&D SIG Database which is maintained at JSC

Stability of Single Particle Tracers for Differentiating Between Heavy- and Light-Duty Vehicle Emissions

To determine the size and chemical composition of particles derived from on-road vehicle emissions, individual particles were sampledcontinuously with an aerosol time-of-flight mass spectrometer (ATOFMS) at the Caldecott Tunnel in Northern California. In this tunnel, traffic is segregated, such that in theory only light duty vehicle emissions or a mix of heavy- (HDV) and light-duty vehicle (LDV) emissions can be sampled separately. Two studies were carried out, one in November 1997 anda secondin July 2000, time periods with average ambient temperatures of 10–15 and 26–32 1C, respectively, with the instrument operating at ambient outdoor temperatures. Analysis of the chemical composition of the particles sampled in these studies shows that sampling conditions can strongly impact the determination of suitable markers for identifying particles emitted from different vehicle types during ambient studies

Effects of donor cause of death, ischemia time, inotrope exposure, troponin values, cardiopulmonary resuscitation, electrocardiographic and echocardiographic data on recipient outcomes: A review of the literature

BackgroundHeart transplantation has become standard of care for pediatric patients with either end‐stage heart failure or inoperable congenital heart defects. Despite increasing surgical complexity and overall volume, however, annual transplant rates remain largely unchanged. Data demonstrating pediatric donor heart refusal rates of 50% suggest optimizing donor utilization is critical. This review evaluated the impact of donor characteristics surrounding the time of death on pediatric heart transplant recipient outcomes.MethodsAn extensive literature review was performed to identify articles focused on donor characteristics surrounding the time of death and their impact on pediatric heart transplant recipient outcomes.ResultsPotential pediatric heart transplant recipient institutions commonly receive data from seven different donor death‐related categories with which to determine organ acceptance: cause of death, need for CPR, serum troponin, inotrope exposure, projected donor ischemia time, electrocardiographic, and echocardiographic results. Although DITs up to 8 hours have been reported with comparable recipient outcomes, most data support minimizing this period to <4 hours. CVA as a cause of death may be associated with decreased recipient survival but is rare in the pediatric population. Otherwise, however, in the setting of an acceptable donor heart with a normal echocardiogram, none of the other data categories surrounding donor death negatively impact pediatric heart transplant recipient survival.ConclusionsEchocardiographic evaluation is the most important donor clinical information following declaration of brain death provided to potential recipient institutions. Considering its relative importance, every effort should be made to allow direct image visualization.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/154939/1/petr13676.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/154939/2/petr13676_am.pd

The Application of Novel Research Technologies by the Deep Pelagic Nekton Dynamics of the Gulf of Mexico (DEEPEND) Consortium

The deep waters of the open ocean represent a major frontier in exploration and scientific understanding. However, modern technological and computational tools are making the deep ocean more accessible than ever before by facilitating increasingly sophisticated studies of deep ocean ecosystems. Here, we describe some of the cutting-edge technologies that have been employed by the Deep Pelagic Nekton Dynamics of the Gulf of Mexico (DEEPEND; www.deependconsortium.org) Consortium to study the biodiverse fauna and dynamic physical-chemical environment of the offshore Gulf of Mexico (GoM) from 0 to 1,500 m

Surface Morphologies in a Mars-Analog Ca-Sulfate Salar, High Andes, Northern Chile

Salar de Pajonales, a Ca-sulfate salt flat in the Chilean High Andes, showcases the type of polyextreme environment recognized as one of the best terrestrial analogs for early Mars because of its aridity, high solar irradiance, salinity, and oxidation. The surface of the salar represents a natural climate-transition experiment where contemporary lagoons transition into infrequently inundated areas, salt crusts, and lastly dry exposed paleoterraces. These surface features represent different evolutionary stages in the transition from previously wetter climatic conditions to much drier conditions today. These same stages closely mirror the climate transition on Mars from a wetter early Noachian to the Noachian/Hesperian. Salar de Pajonales thus provides a unique window into what the last near-surface oases for microbial life on Mars could have been like in hypersaline environments as the climate changed and water disappeared from the surface. Here we open that climatological window by evaluating the narrative recorded in the salar surface morphology and microenvironments and extrapolating to similar paleosettings on Mars. Our observations suggest a strong inter-dependence between small and large scale features that we interpret to be controlled by extrabasinal changes in environmental conditions, such as precipitation-evaporation-balance changes and thermal cycles, and most importantly, by internal processes, such as hydration/dehydration, efflorescence/deliquescence, and recrystallization brought about by physical and chemical processes related to changes in groundwater recharge and volcanic processes. Surface structures and textures record a history of hydrological changes that impact the mineralogy and volume of Ca-sulfate layers comprising most of the salar surface. Similar surface features on Mars, interpreted as products of freeze-thaw cycles, could, instead, be products of water-driven, volume changes in salt deposits. On Mars, surface manifestations of such salt-related processes would point to potential water sources. Because hygroscopic salts have been invoked as sources of localized, transient water sufficient to support terrestrial life, such structures might be good targets for biosignature exploration on Mars

FLIM FRET Technology for Drug Discovery: Automated Multiwell-Plate High-Content Analysis, Multiplexed Readouts and Application in Situ**

A fluorescence lifetime imaging (FLIM) technology platform intended to read out changes in Förster resonance energy transfer (FRET) efficiency is presented for the study of protein interactions across the drug-discovery pipeline. FLIM provides a robust, inherently ratiometric imaging modality for drug discovery that could allow the same sensor constructs to be translated from automated cell-based assays through small transparent organisms such as zebrafish to mammals. To this end, an automated FLIM multiwell-plate reader is described for high content analysis of fixed and live cells, tomographic FLIM in zebrafish and FLIM FRET of live cells via confocal endomicroscopy. For cell-based assays, an exemplar application reading out protein aggregation using FLIM FRET is presented, and the potential for multiple simultaneous FLIM (FRET) readouts in microscopy is illustrated

LKB1 Destabilizes Microtubules in Myoblasts and Contributes to Myoblast Differentiation

Background: Skeletal muscle myoblast differentiation and fusion into multinucleate myotubes is associated with dramatic cytoskeletal changes. We find that microtubules in differentiated myotubes are highly stabilized, but premature microtubule stabilization blocks differentiation. Factors responsible for microtubule destabilization in myoblasts have not been identified. Findings: We find that a transient decrease in microtubule stabilization early during myoblast differentiation precedes the ultimate microtubule stabilization seen in differentiated myotubes. We report a role for the serine-threonine kinase LKB1 in both microtubule destabilization and myoblast differentiation. LKB1 overexpression reduced microtubule elongation in a Nocodazole washout assay, and LKB1 RNAi increased it, showing LKB1 destabilizes microtubule assembly in myoblasts. LKB1 levels and activity increased during myoblast differentiation, along with activation of the known LKB1 substrates AMPactivated protein kinase (AMPK) and microtubule affinity regulating kinases (MARKs). LKB1 overexpression accelerated differentiation, whereas RNAi impaired it. Conclusions: Reduced microtubule stability precedes myoblast differentiation and the associated ultimate microtubule stabilization seen in myotubes. LKB1 plays a positive role in microtubule destabilization in myoblasts and in myoblast differentiation. This work suggests a model by which LKB1-induced microtubule destabilization facilitates the cytoskeleta

Impacts of 1.5°C Global Warming on Natural and Human Systems

An IPCC Special Report on the impacts of global warming of 1.5°C above pre-industrial levels and related global greenhouse gas emission pathways, in the context of strengthening the global response to the threat of climate change, sustainable development, and efforts to eradicate povert

Global transpiration data from sap flow measurements : the SAPFLUXNET database

Plant transpiration links physiological responses of vegetation to water supply and demand with hydrological, energy, and carbon budgets at the land-atmosphere interface. However, despite being the main land evaporative flux at the global scale, transpiration and its response to environmental drivers are currently not well constrained by observations. Here we introduce the first global compilation of whole-plant transpiration data from sap flow measurements (SAPFLUXNET, https://sapfluxnet.creaf.cat/, last access: 8 June 2021). We harmonized and quality-controlled individual datasets supplied by contributors worldwide in a semi-automatic data workflow implemented in the R programming language. Datasets include sub-daily time series of sap flow and hydrometeorological drivers for one or more growing seasons, as well as metadata on the stand characteristics, plant attributes, and technical details of the measurements. SAPFLUXNET contains 202 globally distributed datasets with sap flow time series for 2714 plants, mostly trees, of 174 species. SAPFLUXNET has a broad bioclimatic coverage, with woodland/shrubland and temperate forest biomes especially well represented (80 % of the datasets). The measurements cover a wide variety of stand structural characteristics and plant sizes. The datasets encompass the period between 1995 and 2018, with 50 % of the datasets being at least 3 years long. Accompanying radiation and vapour pressure deficit data are available for most of the datasets, while on-site soil water content is available for 56 % of the datasets. Many datasets contain data for species that make up 90 % or more of the total stand basal area, allowing the estimation of stand transpiration in diverse ecological settings. SAPFLUXNET adds to existing plant trait datasets, ecosystem flux networks, and remote sensing products to help increase our understanding of plant water use, plant responses to drought, and ecohydrological processes. SAPFLUXNET version 0.1.5 is freely available from the Zenodo repository (https://doi.org/10.5281/zenodo.3971689; Poyatos et al., 2020a). The "sapfluxnetr" R package - designed to access, visualize, and process SAPFLUXNET data - is available from CRAN.Peer reviewe