Minutes Of Real Time Research Articles

DEFINING PARAMETERS OF EQUILIBRIUM STRANDING OF A SHIP USING SIMULATION MODELLING

Equilibrium stranding of a ship is a necessary preliminary step for application of other decision support system algorithms, such as identification of a flooded compartment, predicting an emergency vessel capsize probability, and others. The equilibrium stranding using a real ship as an example based on the heel angle sensors readings for rolling and pitching, and the water column pressure sensors readings for the vertical roll, is calculated. In the linear case, the mean value of an individual value coincides with the equilibrium position on the corresponding coordinate axis. However, a ship rolling in a sea is, as a rule, non-linear process, and hence the mathematical average correction is required. The use of the Nechaev’s method for determining the equilibrium position of a floating vessel in a heavy sea is illustrated in the paper. An algorithm based on simulation modeling in the Virtual Testbed software package is proposed. It has been proved that complication of wave model used for coefficients obtaining in Y. I. Nechaev’s algorithm changes obtained equilibrium parameter value insignificantly, but in this case time spent for generation of one simulation is increased significantly enough. When using linear waves or Stokes waves, the generation of two minutes of simulation is faster than two minutes of real time; when using Gerstner waves, the simulation time approaching three minutes of real time, which already exceeds the simulation time. In this case, when using the Stokes waves model, it is possible to achieve the results closer to the Gerstner model than when using the linear waves model without consuming additional time. This fact allows us to conclude about the optimal use of the algorithm.

Diagnostic Significance of Wet Mount Microscopy- A Retrospective Observational Study

Introduction: Wet mount microscopy is a rapid and easy conventional technique that provides a quick answer when positive and it provides an approximation of the infection burden. In this era of modern medicine where almost every infection is being diagnosed, using expensive and sophisticated molecular techniques, a simple wet mount examination of a clinical sample can still be relevant in several infections and play a significant role in the early diagnosis and treatment of infectious diseases. Aim: To focus and review the significance of wet mount examination of clinical specimens for diagnosis. Materials and Methods: A retrospective observational study with 11 cases was conducted at a superspeciality hospital in New Delhi over a period of six months from March 2019 to August 2019. Direct microscopic demonstration of motile E. histolytica trophozoites in saline wet mount of colonic biopsy specimens was done in patients presenting with non specific gastrointestinal symptoms. Positive cases were immediately reported to the clinician for further management. In view of this study, literature search was done on PubMed and Google scholar platforms for studies on wet mount examination of clinical specimens, data was analysed and all infectious diseases were identified for which wet mount microscopy will help in decreasing the Turn around Time (TAT) for diagnosing the infection from 24 hours to 20-30 minutes in real time. Results: Motile trophozoites of E. histolytica were seen in eight out of 11 cases studied. Amoebic serology by Enzyme-linked Immunoassay (ELISA) and histopathology for amoebic trophozoites was positive in all eight patients with 100% association between microscopic demonstrations of motile E. histolytica trophozoites in saline wet mount for amoebiasis. Conclusion: Right test at right time for clinical management of infectious diseases requires good communication between laboratory and clinicians. Direct Wet mount microscopy of clinical samples is rapid, simple, cost-effective method to decrease TAT and guide the clinicians to rule out infections and avoid unnecessary empirical use of antimicrobial drugs.

A class of particulate problems suited to FDEM requiring accurate simulation of shape effects in packed granular structures

In many granular material simulation applications, DEM capability is focused on the dynamic solid particulate flow properties and on systems in which millions of particles are involved. The time of relevance is many seconds or even minutes of real time. Simplifying assumptions are made to achieve run completion in practical timescales. There are certain applications, typically involving manufactured particles, where a representative pack is of the order of a thousand particles. More accurate capturing of the influence of complex shape is then often possible. Higher accuracies are necessary to model the topology of the void space, for example, for further CFD simulation and optimisation of fluid flow properties. Alternatively, the accuracy may be critical for structural performance and the force or stress transmission through the contact points is to be controlled to avoid material damage and poor function. This paper briefly summarises methods for simulation of shape effects on packing structures in the granular community and narrows the scope to problems where shape effects are of overriding concern. Two applications of mono-sized, mono-shaped packing problems are highlighted: catalyst support pellets in gas reforming and concrete armour units in breakwater structures. The clear advantages of FDEM for complex-shaped particle interactions in packed systems with relatively few particles are discussed. A class of particulate problems, ‘FDEM-suited’ problems, ones that are ideal to be solved by FDEM rather than by DEM, is proposed for science and engineering use.

Evolution of a Video-Learning Object Format

In a previous article, Peter J. Fadde emphasized the value of creating an identifiable format for video-learning objects. Developing such a format requires an investment of time and creativity, yet the return-on-investment is significant. In addition, viewers (or learners) know what to expect from each video-learning object -- of key importance with video objects because they can't be perused in a glance. Here, I analyze a series of mini-lecture video-learning objects called 'Real Time Minutes' (RTMs) produced by Jonathan Finkelstein, the creator/curator of Learning Times, an online community for teachers.

The role of magma composition and water content in explosive eruptions: 2. Pyroclastic dispersion dynamics

The net effect of magma composition and water content on the behavior of explosive volcanic eruptions was investigated by the use of thermofluid-dynamic models and numerical simulation. The two-phase flow models employed allowed the description of the eruptive process from the conduit entrance at the top of the magma chamber up to the pyroclastic dispersion process in the atmosphere. In this paper, vent conditions computed in the companion paper by Papale et al. [Papale, P., Neri, A., Macedonio, G., this issue. The role of magma composition and water content in explosive eruptions: I. Conduit ascent dynamics. J. Volcanol. Geotherm. Res.], as a function of magma composition and water content, are employed as boundary conditions at the crater base of the pyroclastic dispersion model. The eruptive mixture was described as a two-phase gas–particle fluid. Pyroclasts are represented as solid particles of one size whereas the gas phase consists of superheated water vapor leaving the vent and atmospheric air. Simulations were performed on physical domains extending several kilometers in both radial and vertical directions and for several minutes of real time. The results clearly show the net effects of the anhydrous magma composition, crystals, and water content on the spatial and temporal distribution of pyroclastic material during the first minutes of eruption. In detail, the results indicate a strong influence of magma composition on eruption intensity, whereas the eruptive style, i.e., the generation of Plinian, transitional, or collapsing columns, appears to be mainly controlled by the total water content of the magma, i.e., the weight fraction of water with respect to the entire magmatic mixture. The main effect of the crystals is to reduce the total water content of the mixture and lead to a less buoyant behavior of the column. As a summary, for the investigated ranges of variations, simulation results indicate a progressive change to a more collapsing behavior of the column whenever water-poorer or crystal-richer magma is erupted from the vent with the anhydrous composition of magma affecting just the intensity of the eruption. For most conditions, such a conclusion does not appear to be strongly dependent on a relatively large variation of vent diameter and, therefore, of the scale of the event. Simulation results appear to be consistent with field studies even though more complete data on specific eruptions are recommended for a more thorough comparison.

Visualization of a single myelination process of an oligodendrocyte in culture by video microscopy.

We described the initial events in the interaction between an oligodendrocyte process and an axon in culture utilizing video time-lapse microscopy. Myelination of an axon by the lamellipodium of an oligodendrocyte was achieved in several steps of cellular process development and coordinated interaction between axon and oligodendrocyte. The initial stage of contact included the formation of a lamellipodium process at the end of an oligodendrocyte process. It appeared that this process contacted the axon several times and was then retracted, and that the filopodia and lamellipodium underwent morphological changes prior to the onset of the myelination. In the second stage, the lamellipodium appeared to thicken and anchor to the axon. Finally, when rippling of the lamellipodial ruffling occurred, the angle between the anchoring filopodium and the axon changed depending on the direction of lamellipodial movement, and the lamellipodium, which was folded in layers, wrapped around the axon like a transverse wave in one motion as observed on the video screen. Thereafter, the lamellipodium assumed a "bursting" form within minutes in real time. This is the first comprehensive overview of how an oligodendrocyte plasma membrane wraps around an axon to form myelin.

Vertex packing problem application to the design of electronic testing fixtures

In this paper, we report on the use of combinatorial optimization techniques to design testing fixtures for Printed Circuit Boards (PCBs). For testing the functionality of a PCB, nail-like testing devices (probes) on the surface of a testing fixture are brought in contact with prespectified test points (pads) on the surface of the PCB. The two design decisions for the testing fixture are: (a) to select from an available set of pads the ones to test (this determines the location of the probes on the fixture) subject to the restriction that in prespecified subsets of the set of pads (these subsets are referred to as “nets”) and a priori determined number of pads have to be tested (this is referred to as the “net restriction”), and (b) to choose the probe size to be used for testing each pad (only two available sizes: a large (100 mil) and a small (50 mil)) subject to the considerations that larger size probes are more reliable for testing purposes and probes that are assigned to pads in close proximity should not come in physical contact with each other (it creates short circuits and erroneous test result). Thus, the problem the testing engineer faces is to assign the maximum number of 100 mil probes to an appropriately selected set of pads in a way that avoids the creation of short circuits and accounts for the “net restriction”. We develop an efficient algorithm to solve the problem using results from the vertex packing literature, which exploit the special structure of an appropriate geometric graph we can define in this application. The algorithm can handle the large size real problem within 2–3 minutes of real time on a microcomputer.

One‐dimensional hybrid simulations of current sheets in the quiet magnetotail

Hybrid simulations (kinetic ions, massless fluid electrons) have been performed of the magnetotail current sheet for parameters characteristic of the quiet magnetotail (υD, bn < 1). Here bn = Bn/B0,υD = (cEy/Bn)/υi,Bn is the north / south (z) magnetic field, B0 the asymptotic value of the tailward (x) field and υi the ion thermal speed, where the magnetospheric coordinate system is used. It is shown that the current sheet is more stable than in previously examined cases with high υD and / or large bn. A clear single reversal in Bx persists over the entire simulation and a By component is created, with a slow rate of growth (hundreds of Ωi−1, where Ωi = eB0/miC). This is many minutes in real time. It is suggested that the waves are due to an electromagnetic instability of the cross‐field ion current.

How do oligodendrocytes ensheath and myelinate nerve fibers?

Oligodendrocyte precursor cells were cultured from newborn rat brain and studied their differentiation and proliferation. They have identified type-1, type-2, and type-3 oligodendrocytes based on the expression of characteristic marker molecules that frequently used to stage oligodendrocyte development. The type-3 oligodendrocytes were observed to send but tentative that locate axons prior to myelination. These processes terminate in lamellipodia, which eventually enwrap the axon and begin the myelination process with several steps. At the first stage, ruffling is immediately induced at the lamellipodia with filopodia made of oligodendrocyte processes, and the axon is contacted several times; then process retraction occurs to reform the filopodial and lamellipodial parts prior to the onset of the myelination. Second, after filopodia] movements and lamellipodial ruffling occur again, their morphology is dramatically changed to become three thick filopodia that anchor to the axon. Finally, lamellipodial ruffling parts ripple, the angle between the position of the resting filopodium and the axon change, depending on the start of axonal movement, and the lamellipodia turn around the axon like a transverse wave with one stroke of the brush, as observed on the video screen, and their rolling membrane changes to the bursting form within minutes in real time.

Determination of spherical voids in layered structures (void program)

An APL program has been written to compute the locations and the radii of spherical voids between two packing layers of atoms, and to obtain plottings which correspond to the various types of standard sheets used for the representation of crystal structures according to the condensed-model technique. Conversational facilities, together with the use of original APL routines, enable the crystallographer to get the results in a few minutes of real time.