Deconstructing Spinal Interneurons, one cell type at a time

Documenting the extent of cellular diversity is a critical step in defining the functional organization of the nervous system. In this context, we sought to develop statistical methods capable of revealing underlying cellular diversity given incomplete data sampling - a common problem in biological systems, where complete descriptions of cellular characteristics are rarely available. We devised a sparse Bayesian framework that infers cell type diversity from partial or incomplete transcription factor expression data. This framework appropriately handles estimation uncertainty, can incorporate multiple cellular characteristics, and can be used to optimize experimental design. We applied this framework to characterize a cardinal inhibitory population in the spinal cord. Animals generate movement by engaging spinal circuits that direct precise sequences of muscle contraction, but the identity and organizational logic of local interneurons that lie at the core of these circuits remain unresolved. By using our Sparse Bayesian approach, we showed that V1 interneurons, a major inhibitory population that controls motor output, fractionate into diverse subsets on the basis of the expression of nineteen transcription factors. Transcriptionally defined subsets exhibit highly structured spatial distributions with mediolateral and dorsoventral positional biases. These distinctions in settling position are largely predictive of patterns of input from sensory and motor neurons, arguing that settling position is a determinant of inhibitory microcircuit organization. Finally, we extensively validated inferred cell types by direct experimental measurement and then, extend our Bayesian framework to full transcriptome technologies. Together, these findings provide insight into the diversity and organizational logic through which inhibitory microcircuits shape motor output

Estudio de la transferencia de materia sólido-líquido en un reactor de lecho mojado

Fil: Gabitto, Jorge Federico. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

TRANSPORT AND PHASE EQUILIBRIA PROPERITIES FOR STEAM FLOODING OF HEAVY OILS

Hydrocarbon/water and CO{sub 2} systems are frequently found in petroleum recovery processes, petroleum refining, and gasification of coals, lignites and tar sands. Techniques to estimate the phase volume and phase composition are indispensable to design and improve oil recovery processes such as steam, hot water, or CO{sub 2}/steam combinations of flooding techniques typically used for heavy oils. An interdisciplinary research program to quantify transport, PVT, and equilibrium properties of selected oil/CO{sub 2}/water mixtures at pressures up to 10,000 psia and at temperatures up to 500 F has been put in place. The objectives of this research include experimental determination and rigorous modeling and computation of phase equilibrium diagrams, and volumetric properties of hydrocarbon/CO{sub 2}/water mixtures at pressures and temperatures typical of steam injection processes for thermal recovery of heavy oils. Highlighting the importance of phase behavior, researchers ([1], and [2]) insist on obtaining truly representative reservoir fluids samples for experimental analysis. The prevailing sampling techniques used for compositional analysis of the fluids have potential for a large source of error. These techniques bring the sample to atmospheric conditions and collect the liquid and vapor portion of the samples for further analysis. We developed a new experimental technique to determine phase volumes, compositions and equilibrium K-values at reservoir conditions. The new methodology is able to measure phase volume and composition at reservoir like temperatures and pressures. We use a mercury free PVT system in conjunction with a Hewlett Packard gas chromatograph capable of measuring compositions on line at high pressures and temperatures. This is made possible by an essentially negligible disturbance of the temperature and pressure equilibrium during phase volume and composition measurements. In addition, not many samples are withdrawn for compositional analysis because a negligible volume (0.1 {micro}l to 0.5 {micro}l) is sent directly to the gas chromatograph through sampling valves. These amounts are less than 1 x 10{sup -5} % of total volume and do not affect the overall composition or equilibrium of the system. A new method to compute multi-component phase equilibrium diagrams based on an improved version of the Peng-Robinson equation has been developed [3]. This new version of the Peng-Robinson equation uses a new volume translation scheme and new mixing rules to improve the accuracy of the calculations. Calculations involving multicomponent mixtures of CO{sub 2}/water and hydrocarbons have been completed. A scheme to lump multi-component materials such as, oils into a small set of ''pseudo-components'' according to the technique outlined by Whitson [4] has been implemented. This final report presents the results of our experimental and predicted phase behavior diagrams and calculations for mixtures of CO{sub 2}/water and real oils at high pressures and temperatures

Gas Hydrates Research Programs: An International Review

Gas hydrates sediments have the potential of providing a huge amount of natural gas for human use. Hydrate sediments have been found in many different regions where the required temperature and pressure conditions have been satisfied. Resource exploitation is related to the safe dissociation of the gas hydrate sediments. Basic depressurization techniques and thermal stimulation processes have been tried in pilot efforts to exploit the resource. There is a growing interest in gas hydrates all over the world due to the inevitable decline of oil and gas reserves. Many different countries are interested in this valuable resource. Unsurprisingly, developed countries with limited energy resources have taken the lead in worldwide gas hydrates research and exploration. The goal of this research project is to collect information in order to record and evaluate the relative strengths and goals of the different gas hydrates programs throughout the world. A thorough literature search about gas hydrates research activities has been conducted. The main participants in the research effort have been identified and summaries of their past and present activities reported. An evaluation section discussing present and future research activities has also been included

Aerodynamics of long fibres settling in air at 10<Re<100

The aerodynamics of long aspect ratio nylon fibrous particles has been investigated experimentally whilst settling in air under super dilute conditions without any influence of secondary flows and at fibre Reynolds numbers of 10–100 based on fibre length. Measurement of the orientations and velocities of fibrous particles is undertaken by two-dimensional Particle Tracking Velocimetry (PTV), based on the two end-points. A statistical evaluation of fibres' mean vertical and horizontal components of settling velocities, angular velocity, orientation, number density is presented and used to assess particle aerodynamics.Guo Q. Qi, Graham J. Nathan, Richard M. Kels

PTV measurement of drag coefficient of fibrous particles with large aspect ratio

The aerodynamic behaviour of long aspect ratio nylon fibrous particles has been investigated experimentally while settling in air under super dilute conditions without any influence of secondary flows and at fibre Reynolds numbers of 0.5-2 based on fibre diameter. A method for laser-based measurement of the orientations and velocities of fibrous particles is also presented. The experimental apparatus employs a two-dimensional Particle Tracking Velocimetry (PTV) to calculate orientation and velocity based on the two end-points. The controlling length scale in the relationship between Reynolds number and drag coefficient was investigated and the equivalent diameter of settling fibre in air was reported. Finally the influence of volume fraction and fibre straightness were assessed. © 2012.Guo Q. Qi, Graham J. Nathan, Richard M. Kels

A new era for space life science: international standards for space omics processing

10 p.-2 fig.Space agencies have announced plans for human missions to the Moon to prepare for Mars. However, the space environment presents stressors that include radiation, microgravity, and isolation. Understanding how these factors affect biology is crucial for safe and effective crewed space exploration. There is a need to develop countermeasures, to adapt plants and microbes for nutrient sources and bioregenerative life support, and to limit pathogen infection. Scientists across the world are conducting space omics experiments on model organisms and, more recently, on humans. Optimal extraction of actionable scientific discoveries from these precious datasets will only occur at the collective level with improved standardization. To address this shortcoming, we established ISSOP (International Standards for Space Omics Processing), an international consortium of scientists who aim to enhance standard guidelines between space biologists at a global level. Here we introduce our consortium and share past lessons learned and future challenges related to spaceflight omics.European (D.B., H.C., N.J.S., R.H., and S. Giacomello) contribution is supported by ESA Topical Team “Space Omics: Towards an integrated ESA/NASA –omics database for spaceflight and ground facilities experiments” grant 4000131202/20/NL/PG/pt to R.H. S. Giacomello is supported by Formas grant 2017-01066_3. H.C. is supported by the Horizon Centre for Doctoral Training at the University of Nottingham (UKRI grant no. EP/S023305/1) and by the NASA GeneLab Animal Analysis Working Group. N.J.S. is supported by the National Aeronautics and Space Administration (NNX15AL16G). NASA GeneLab members (J.M.G., S.V.C., S.S.R., L.D., S. Gebre) are supported by the NASA Space Biology program within the NASA Science Mission Directorate's (SMD) Biological and Physical Sciences (BPS) Division. R.B. and S. Gilroy are supported by NASA (80NSSC19K0132). L.R. and M.M. represent the Omics Subgroup of Japan Society for the Promotion of Science (JSPS) KAKENHI funding group Living in Space and are supported by JP15K21745, JP15H05940, and JP20H03234. L.R. is supported by JSPS postdoctoral fellowship P20382. D.T. is supported by the Department of Biomedical and Health Informatics and The Children’s Hospital of Philadelphia Research Institute. K.F. is supported by the UC San Diego Department of Medicine and National Institutes of Health, grant UL1TR001442 of CTSA (Clinical and Translational Science Awards). C.E.M. is funded from the WorldQuant Foundation, The Pershing Square Sohn Cancer Research Alliance, and the National Institutes of Health (R01MH117406).Peer reviewe

Emerging CO2 capture systems

In 2005, the IPCC SRCCS recognized the large potential for developing and scaling up a wide range of emerging CO2 capture technologies that promised to deliver lower energy penalties and cost. These included new energy conversion technologies such as chemical looping and novel capture systems based on the use of solid sorbents or membrane-based separation systems. In the last 10 years, a substantial body of scientific and technical literature on these topics has been produced from a large number of R&D projects worldwide, trying to demonstrate these concepts at increasing pilot scales, test and model the performance of key components at bench scale, investigate and develop improved functional materials, optimize the full process schemes with a view to a wide range of industrial applications, and to carry out more rigorous cost studies etc. This paper presents a general and critical review of the state of the art of these emerging CO2 capture technologies paying special attention to specific process routes that have undergone a substantial increase in technical readiness level toward the large scales required by any CO2 capture system

Estudio de la transferencia de materia sólido-líquido en un reactor de lecho mojado

Fil: Gabitto, Jorge Federico. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina

One- and Two-Equation Models to Simulate Ion Transport in Charged Porous Electrodes

Energy storage in porous capacitor materials, capacitive deionization (CDI) for water desalination, capacitive energy generation, geophysical applications, and removal of heavy ions from wastewater streams are some examples of processes where understanding of ionic transport processes in charged porous media is very important. In this work, one- and two-equation models are derived to simulate ionic transport processes in heterogeneous porous media comprising two different pore sizes. It is based on a theory for capacitive charging by ideally polarizable porous electrodes without Faradaic reactions or specific adsorption of ions. A two-step volume averaging technique is used to derive the averaged transport equations for multi-ionic systems without any further assumptions, such as thin electrical double layers or Donnan equilibrium. A comparison between both models is presented. The effective transport parameters for isotropic porous media are calculated by solving the corresponding closure problems. An approximate analytical procedure is proposed to solve the closure problems. Numerical and theoretical calculations show that the approximate analytical procedure yields adequate solutions. A theoretical analysis shows that the value of interphase pseudo-transport coefficients determines which model to use