Diagonal Interface Research Articles

Customizable OpenGUS immunoassay: A homogeneous detection system using β-glucuronidase switch and label-free antibody

We developed a customizable OpenGUS immunoassay that enables rapid and sensitive detection of analytes without requiring antibody modification. This immunoassay employs label-free whole antibodies, an antibody-binding Z domain (ZD) derived from Staphylococcal protein A, and a β-glucuronidase (GUS) switch mutant, allowing for easy replacement of antibodies to tailor the immunoassays for various targeted antigens. The working principle is that the OpenGUS probe, the fusion protein of ZD and a GUS switch, converts the antibody-antigen interaction into GUS activation in a one-pot reaction. To enhance the signal-to-background ratio of the immunoassay, a GUS switch mutant that exhibits reduced background activation was developed by screening several additional mutations at the diagonal interface residue H514. Moreover, we optimized the composition of the reaction buffer, including organic solvents, salt, and surfactant. Under optimal conditions, we customized OpenGUS immunoassays for Cry j 1, human C-reactive protein, and human lactoferrin, achieving around 10–20-fold maximum fluorescence (15 min) or colorimetric (2 h) responses with picomolar to low nanomolar level detection limit, simply by using commercially available IgGs. Additionally, the three analytes were successfully detected in complex matrices similar to those used in practical applications. We believe that this customizable OpenGUS immunoassay will pave the way for the prompt development of rapid and sensitive homogeneous immunoassays for point-of-care diagnostics, high-throughput testing, and onsite environmental assessments.

The effect of terrain-influenced winds on fire spread in QUIC-Fire

In this manuscript, we describe the implementation of the terrain-following version of QUIC-URB into QUIC-Fire and a demonstration of the impacts of terrain-influenced winds on QUIC-Fire-simulated fire spread. No changes to the underlying QUIC-Fire fire spread algorithm were made other than what was required to correctly account for the inclusion of terrain. This paper summarizes simulations used to understand how the QUIC-URB terrain-influenced winds affect upslope fire behavior without additional changes to the QUIC-Fire fire spread algorithm. Previously published FIRETEC results are compared to simulation results from the modified QUIC-Fire (incorporating terrain-influenced winds) that use the same topographies and fuels. QUIC-Fire results showed overall similar behaviors in terms of how the topographies affected fire shapes and trends in spread rates. Due to the terrain-following version of QUIC-URB being unable to generate flow separations at the crest of hills, fire spread rates in these regions across all non-flat topographies were over-predicted when compared to FIRETEC. Lateral fire growth showed similar trends with FIRETEC between topographies but did not capture the increase in spread due to a diagonal interface between grassland and forested fuel regions in the test domain. These simulations suggest possible refinements that are necessary to improve QUIC-Fire and thus guide ongoing efforts related to: how flame tilt angle is accounted for, the incorporation of non-local drag effects, and the inclusion of the wake-eddy parameterizations that are used in QUIC-URB.

The Serpentine Illusion: A Visual Motion Illusion Induced by Phase-Shifted Line Gratings.

In a pattern of horizontal lines containing ± 45° zigzagging phase-shifted strips, vivid illusory motion is perceived when the pattern is translated up or down at a moderate speed. Two forms of illusory motion are seen: [i] a motion “racing” along the diagonal interface between the strips and [ii] lateral (sideways) motion of the strip sections. We found the relative salience of these two illusory motions to be strongly influenced by the vertical spacing and length of the line gratings, and the period length of the zigzag strips. Both illusory motions are abolished when the abutting strips are interleaved, separated by a gap or when a real line is superimposed at the interface. Illusory motion is also severely weakened when equiluminant colored grating lines are used. Illusory motion perception is fully restored at < 20% luminance contrast. Using adaptation, we find that line-ends alone are insufficient for illusory motion perception, and that both physical carrier motion and line orientation are required. We finally test a classical spatiotemporal energy model of V1 cells that exhibit direction tuning changes that are consistent with the direction of illusory motion. Taking this data together, we constructed a new visual illusion and surmise its origin to interactions of spatial and temporal energy of the lines and line-ends preferentially driving the magnocellular pathway.

A new apparent shear stress-based approach for predicting discharge in uniformly roughened straight compound channels

Accurately predicting flow discharge in a compound river channel becomes increasingly important when in river eco-environment design and flood risk management, in which the conventional methods, such as divided channel method (DCM) and single channel method, do not meet precision requirement. In the present paper, a new approach is proposed to improve the prediction of flow based on the concept of the apparent shear stress at the diagonal interface between main channel and floodplains. The new approach is compared with a wide range of the author's experimental data and the data available in the literature. The 27 datasets used in this study cover homogenous symmetric channels (22 datasets) and asymmetric channels (5 datasets), which have various width ratios [channel total width (B) at bankfull / main channel bottom (b) = 1.5 ~ 15.8] and bed slopes (So = 2.6 × 10−4 ~2.5 × 10−3). It was found that the new approach can significantly improve the accuracy of flow prediction compared with the conventional DCM for all the datasets, particularly for relatively low flow depths of floodplain (e.g. Dr < 0.15) where the flow discharge was very difficult to predict correctly. The new approach predicts the total discharge well for straight homogeneously symmetric and asymmetric channels, within a mean absolute percentage error (MAPE) of 5%. Furthermore, compared with the DCM, the new approach can also have a better prediction of zonal discharge percentage and it has less variation of discharge prediction error over the flow depth.

Φ-indices approach and multivariable regression analysis for prediction of discharge in asymmetric straight compound open channel flows

This study is related to flow measurement structures of asymmetric compound cross section mostly suggested for sediment laden-rivers, streams and wadis. Nine different models of asymmetrical rectangular cross sections were tested for a wide range of discharges. In each model, the stages and corresponding discharges were measured. From these measurements, the average discharges utilizing the Φ-indices Approach were determined. In addition, a multivariable regression model was derived with high accuracy for the prediction of discharge in asymmetric compound channels using five dimensionless parameters.The measured discharges were compared with the predicted ones obtained from the Φ-indices methods with vertical, horizontal and diagonal interface planes; FI-V, FI-D and FI-H, respectively, with the use of three well-known methods for the computation of the apparent shear stress acting on the interface perimeter, τa, and the multivariable regression model for discharge prediction. At lower relative depth values, almost all the tested methods predict discharge with acceptable accuracy. In addition, as the relative depth increases, the results demonstrate a suitable accuracy of the FI-V with the vertical division lines and the multivariable regression model method. The multivariable regression model presented has been identified as the best-fit model in 26 cases out of 29 through minimization of the mean squared errors.

Human-induced geological hazards along the Dead Sea coast

The Dead Sea is a terminal lake whose level is currently dropping at a rate of about 1 m per year due to the over exploitation of all its tributaries. The lowering started about four decades ago but geological hazards appeared more and more frequently from the end of the 1980s. The water level lowering is matched by a parallel groundwater level drop, which results in an increasing intensity of underground and surface water flow. The diagonal interface between the Dead Sea brine and the fresh groundwater is pushed downwards and seawards. Nowadays, sinkholes, subsidence, landslides and reactivated salt-karsts affect wide coastal segments. Until now, mainly infrastructures were damaged and few people/animals were injured, but the ongoing development of tourism in this very attractive situation will increase the risk if precautionary measures are not included in the development plans. This paper discusses the main observations made all around the Dead Sea and shed a light on the differences between the geological hazards of the western shore (Israel, Palestinian Authority) and the eastern shore (Jordan). It is the first attempt to bring together an overview of the human-induced geological hazards encountered along the Dead Sea coast.

DISCHARGE ESTIMATION METHODS FOR STEADY COMPOUND CHANNEL FLOWS

This study evaluates various alternatives to account for flood plain conveyance in steady compound channel flows. Evaluations are based on applying several traditional discharge estimation methods to a steady, uniform flow laboratory data set. Many of the applied techniques overestimate compound channel discharge. Six interface and two other standard methods for computing discharge in open channels were compared. Each interface method uses a particular arrangement of imaginary interface planes to artificially sub-divide the compound flow field into homogeneous zones. These methods are named for the particular interface plane arrangement adopted. The two standard methods do not involve interface planes. In general, among the methods tested, the outward-facing diagonal interface plane method and the vertical interface plane method produced the most accurate simulations.

Modelling floodplain conveyance in compound channel flows

Floodplain conveyance in compound channel flows is examined through applications of the dynamic flow routing model DWOPER to both laboratory and field data sets. Three different approaches regarding the modelling of off-channel storage are considered, namely, the single-channel approach and two interface-plane methods, which artificially separate main channel flows from floodplain flows, using (i) vertical and (ii) diagonal interface planes. The single-channel method, which views composite flow fields as single units without storage, produced significant differences between simulated and observed stage and discharge hydrographs. The vertical interface method gave generally good results in the case of the laboratory data, but was less successful when applied to the field data. The diagonal interface method, which in this instance applied outward-facing diagonal interface planes at the junctions of the main channel and floodplain zones, produced superior results overall. Key words: floodplain, conveyance, unsteady flow, compound channels, off-channel storage, interface planes.

Interface free energy and critical line for the ising model with nearest and next-nearest-neighbor interactions

A method due to Muller-Hartmann and Zittartz is used to calculate the free energy of a diagonal interface in an Ising model on a square lattice with interactions between nearest and next-nearest neighbors. Instead of solving the full bulk problem, one only takes into account a simple subset of interface configurations. The subset, which is somewhat different from that considered by Muller-Hartmann and Zittartz, is chosen in such a way that exact results for the interface free energy are reproduced if the system has only nearest or only next-nearest-neighbor interactions. When the critical line of ferromagnetic transitions is obtained by demanding that the interface free energy as a function of both couplings vanish, a surprisingly accurate approximation is obtained.

Diagonal interface in the two-dimensional Ising ferromagnet

The surface tension of a diagonal interface for the two-dimensional Ising ferromagnet is determined; it is direction dependent, but the critical exponent is always unity. The associated interface is diffuse.