Johns Hopkins Research Data Repository
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Data associated with “Direct Effects of CO2 Radiative Forcing on Ocean Heat Content and Circulation”
No full textOutput of atmospheric general circulation model (GCM) simulations are used to force an ocean-only GCM with comprehensive boundary conditions to examine the impact of direct atmospheric effects on ocean heat content. Perturbation simulations with prescribed response to quadrupling of atmospheric CO2 include altered surface winds, freshwater fluxes, and downwelling shortwave radiation
Land cover map of the Ethiopian Blue Nile River Basin
No full textThis dataset is a land cover map of the Ethiopian portion of the Blue Nile Basin, called the Abay Basin in Ethiopia. It was generated using remotely sensed data to classify land cover into eight broad classes: agriculture, grassland, woodland/shrub, forest, bare ground, urban/impervious surfaces, water, and seasonal water/marsh areas. We used data from Landsat spectral bands from 2000 to 2011, the Normalized Difference Vegetation Index (NDVI) and its temporal mean and variance, together with a digital elevation model, all at 30-m spatial resolution, as inputs to a supervised classifier. A Support Vector Machines algorithm (SVM) was chosen to deal with the size, variability and non-parametric nature of these data stacks. In post-processing, an image segmentation algorithm with a minimum mapping unit of about 0.5 hectares was used to convert per pixel classification results into an object based final map
Data associated with the publication "Cytokine, chemokine and cytokine receptor changes are associated with metabolic improvements after bariatric surgery."
No full textObesity is associated with a chronic state of inflammation characterized by changes in adipokines and cytokines. We conducted a large, comprehensive profiling of cytokines, chemokines and secreted cytokine receptors in lean and obese individuals, and in obese patients undergoing bariatric surgery
Data associated with publication “Where does Titan Sand Come From: Insight from Mechanical Properties of Titan Sand Candidates”
No full textThe data files include original indentation data (load, depth, modulus, hardness) produced by a nanoindenter (Nanomechanics, Inc) for various Titan sand related materials, and AFM/SEM images of the indented cracks of some of materials.
Extensive equatorial linear dunes exist on Titan, but the origin of the sand, which appears to be organic, is unknown. We used nanoindentation to study the mechanical properties of a few Titan sand candidates, several natural sands on Earth, and common materials used in the Titan Wind Tunnel, to understand the mobility of Titan sand. We measured the elastic modulus (E), hardness (H), and fracture toughness (Kc) of these materials. Tholin's elastic modulus (10.4+/-0.5 GPa) and hardness (0.53+/-0.03 GPa) are both an order of magnitude smaller than silicate sand, which is also smaller than the mechanically weak white gypsum sand. With a magnitude smaller fracture toughness (Kc=0.036+/-0.007 MPa-m^(1/2)), tholin is also much more brittle than silicate sand. This indicates that sand formation mechanisms that require liquid hydrocarbons must be possible in the equatorial regions or sand formation does not require liquid, because tholin is too soft and brittle to transport from the poles, where the current lakes and seas are, to the equator.</p
Computing in the Engineering Core Curriculum at JHU
No full textReport prepared at the behest of the dean of engineering at JHU between Summer 2016 and Spring 2017, 17 pages
Data and software associated with publication "Closed-Loop Control of Active Sensing Movements Regulates Sensory Slip”
No full textThis project includes datasets of experiments conducted with weakly electric fish Eigenmannia virescens while tracking a moving refuge. In this project we studied how the reafferent feedback shapes the active movement of E. viresecens. To test this, we created a novel experimental apparatus that allowed us to manipulate the gain of reafferent feedback in freely swimming weakly electric fish in different experimental topologies -- open- and closed-loop control. The data were collected in the LIMBS laboratory at JHU in 2016. The project includes raw (.csv) as well as the processed data (.mat) files for closed-loop and open-loop experimental framework, MATLAB scripts for data analysis, reproduction of the result figures and table data of statistical analysis from Biswas et al., Current Biology, 2018
Data associated with publication “Highly Contrasting Static Charging and Bias Stress Effects in Pentacene Transistors with Polystyrene Heterostructures Incorporating Oxidizable N,N’-bis(4-Methoxyphenyl)aniline Side Chains as Gate Dielectrics”
No full textCharge storage and trapping properties of polymer dielectrics govern the charge densities of adjacent semiconductors and greatly influence the on-off switching voltage (threshold voltage, Vth) of organic field-effect transistors (OFETs) when the polymers are used as gate insulators. Intentional charging of polymer dielectrics in OFETs can change Vth and affect the bias stress. We describe a chemical design and fabrication protocol to construct multilayer-stack dielectrics for pentacene-based OFETs using different polystyrene (PS)-based polymers in each layer, with oxidizable N,N-bis(4-methoxyphenyl)anilino (TPAOMe)-substituted styrene copolymers in arbitrary vertical positions in the stacks. Thermal, byproduct-free crosslinking of benzocyclobutene subunits provides integrity to the multilayer structure by preventing dissolution of the previous deposited layer. Neutron reflectivity data verified the multilayer morphology. We compared the Vth shift before and after charging the stacks by application of ±100V across 0.5-1 µm total film thicknesses. Bias stress was the dominant effect in bilayer devices with a TPAOMe layer in contact with the pentacene, indicated by the direction of Vth shift associated with either polarity of external electric field. In structures with no TPAOMe subunit in contact with the pentacene, when charging with -100V on top of the source and drain electrodes, electron injection from pentacene to dielectric was the major charging mechanism, again consistent with the bias stress direction. When charging with +100V, bilayer devices without TPAOMe showed little change in Vth, suggesting there was no bias stress effect or charge injection in these devices for this charging polarity. For the bilayer devices with the TPAOMe layer in the bottom, and the trilayer devices with TPOMe in the middle, when +100V was applied, the Vth shifts were opposite those expected from bias stress. Dipole formation or partial ionization of chargeable groups at the interface between the dielectric layers are likely polarization mechanisms in these cases. A simple analytical model supports the plausibility of these mechanisms. This work provides examples of both stabilization and shifting of Vth, and therefore controlling charge carrier density, in semiconductors overlying the dielectric multilayers
Light attenuation in the ocean by yellowing materials: Earth System Model simulations
No full textColored detrital matter (CDM) consists of dissolved organic molecules and detrital materials that impart a yellow shift to the ocean’s color. We ran two climate model simulations: one of an ocean including CDM (”Yellow Ocean”) and one without (”Green Ocean”). The differences between these simulations show the impacts of decreased water clarity in the Yellow Ocean. Implications for ocean biogeochemistry and physics are presented in the associated publications
Data associated with the publication: Variations in ocean deoxygenation across Earth System Models: Isolating the role of parametrized lateral mixing
No full textExamines the impact of changing the lateral mixing coefficient within a single Earth System Model on oxygen distribution under global warming. Results from six simulations are shown, four with constant values of mixing coefficient and two with spatially varying values of mixing coefficient
Data associated with the publication 'Nonvolatile Solid-State Charged-Polymer Gating of Topological Insulators into the Topological Insulating Regime'
No full textData tables and graphs in Igor Pro graphing software format producing figures in the associated publication. Abstract: We demonstrate the ability to reduce the carrier concentration of thin films of the topological insulator (TI) Bi2Se3 by utilizing a nonvolatile electrostatic gating via corona charging of electret polymers. Sufficient electric field can be imparted to a polymer-TI bilayer to result in significant electron density depletion, even without the continuous connection of a gate electrode or the chemical modification of the TI. We show that the Fermi level of Bi2Se3 is shifted toward the Dirac point with this method. Using terahertz spectroscopy, we find that the surface chemical potential is lowered into the bulk band gap (approximately 50 meV above the Dirac point and 170 meV below the conduction-band minimum), and it is stabilized in the intrinsic regime while enhancing electron mobility. The mobility of surface state electrons is enhanced to a value as high as approximately 1600cm2/Vs at 5 K