bluuebunny/crossref_metadata_2025 huggingface dataset:
Ketogenic Diet Therapies for Seizures and Status Epilepticus
Authors: McDonald Tanya J. W. , Cervenka Mackenzie C.
Published: November 2020

Ketogenic diet therapies are high-fat, low-carbohydrate diets designed to mimic a fasting state. Although initially developed nearly one century ago for seizure management, most clinical trials for the management of drug-resistant epilepsy in children as well as adults have been conducted over the last 3 decades. Moreover, ketogenic diets offer promising new adjunctive strategies in the critical care setting for the resolution of acute status epilepticus when traditional antiseizure drugs and anesthetic agents fail. Here, we review the history of ketogenic diet development, the clinical evidence supporting its use for the treatment of drug-resistant epilepsy in children and adults, and the early evidence supporting ketogenic diet feasibility, safety, and potential efficacy in the management of status epilepticus.
4.4.28.17 α-Silyl Alcohols, Ethers, and Amines (Update 2020)
Authors: Zhang Q.-W. , An K. , He W.
Published: November 2020

This chapter is an update to the earlier Science of Synthesis contribution (Section 4.4.28) describing methods for the synthesis of α-silyl alcohols, ethers, and amines. Recent approaches in this area have been achieved by virtue of transition-metal catalysis and ligand-controlled asymmetric synthesis. This review focuses on the literature published from 2000 to 2019.
14.7.5 Benzothiopyrylium Salts (Update 2020)
Authors: Lu J.-M. , Shao L.-X.
Published: November 2020

This chapter is an update to the original Science of Synthesis contribution (Section 14.7) describing methods for the synthesis of benzothiopyrylium salts. Although this update also covers new approaches to 1- and 2-benzothiopyrylium salts, most methods developed during recent years have focused on dibenzo[b,e]thiopyrylium salts.
14.4.20 9H-Xanthene-9-thiones (Update 2020)
Authors: Gao W.-C. , Tian J.
Published: November 2020

This chapter is an update to the earlier Science of Synthesis contribution (Section 14.4.11) describing methods for the synthesis of 9H-xanthene-9-thiones. This update describes the use of thionation reagents for the preparation of 9H-xanthene-9-thiones from pre-existing xanthene-type cyclic frameworks.
Discovering new electronic materials despite the small data problem
Authors: Patrick Chris
Published: November 2020

An adaptive optimization engine identifies 12 functional and synthesizable metal-insulator transition materials without a large starting data set.
Theoretical study of the decomposition mechanism of C5F10O in the presence of Cu vapor
Authors: Fu Yuwei , Yang Lei , Li Xingdi , He Mengsha
Published: November 2020

C5F10O is one of the promising SF6 replacements in power switchgears due to its low global warm potential and high dielectric strength. As Cu metal evaporated by discharges and overheat faults in power switchgears will change the decomposition mechanism and products of C5F10O, the interaction between C5F10O and Cu vapor is important to evaluate the arc-quenching behavior but seldom reported yet. Therefore, this paper is focused on the impacts of Cu vapor, mainly released from the contacts in circuit breakers, on the decomposition mechanism and products of C5F10O. The molecular geometries, harmonic vibrational frequencies, and energetic information of products, reactants, and transition states in C5F10O + Cu decomposition pathways including 19 reactions were calculated by density functional theory. The main decomposition reactions and products were selected based on the analysis of rate constants. This work is hopeful to evaluate the arc-quenching behavior of C5F10O-insulated power equipment considering the evaporation from Cu contacts.
1986
Authors: Crane H. Richard
Published: November 2020

It sometimes happens that an old device or method has a rebirth because of new materials or components that have become available from neighboring fields. That happened to the ring interferometer, in a striking way. What does it do? If the entire apparatus is mounted on a turntable, and the turntable is rotated, it will measure the rate of turning with respect to the cosmic inertial reference frame; that is, with respect to the universe of stars. Let’s see what the old, basic idea is, and then see how modern improvements have increased its precision by many orders of magnitude.
STUDENT ASSIGNMENTS
Authors: Feltyberger Earl R. , Mallmann James , Schmidt Judy M. , Senior Thomas
Published: November 2020

For each of the arrangements of metal plates shown below, the plate on the left is attached to the negative terminal of a five volt D.C. power supply and the plate on the right is attached to the positive terminal of the power supply. Based on your experience in mapping electric fields, draw the +4V, +3V, +2V, and +1V lines for each field. Be sure to label each line with its proper voltage.
PHYSICS OLYMPICS EVENTS
Authors: Feltyberger Earl R. , Mallmann James , Schmidt Judy M. , Senior Thomas
Published: November 2020

Two ring stands will be set up 1.0 m apart and connected together electrically with a 1.5 V or 3.0 V battery in series with an ammeter and a small light bulb.(to protect the meter from accidental extreme currents).
Space
Authors: Nelson Jane Bray , Nelson Jim
Published: November 2020

The following activities are presented: Activity 5. Traveling Washer in One Dimension.Activity 6. Traveling Washer in Two Dimensions.Activity 7. Position vs. Time Graphs Using a Motion Probe.Activity 8. Where Am I?Miscellaneous Demonstrations and Activities for Study of Space.
Acceleration
Authors: Nelson Jane Bray , Nelson Jim
Published: November 2020

The following activities are presented: Activity 23. Position, Velocity, & Acceleration vs. Time Graphs Using “Moving Man”.Activity 24. Freely Falling Object I.Activity 25. Freely Falling Object II.Activity 26. Freely Falling Object III.Activity 27. Freely Falling Object IV, Free Fall Simulation.Activity 28. The Case of the Slope Shifter (Four Chapters).Activity 29. Worksheet — Straight Line Motion Equations and Graphs.Activity 30. Measurement of Acceleration Due to Gravitational Force.Activity 31. Measurement of Acceleration on an Inclined PlaneActivity 32. Measurement of Reaction Time with a Falling Ruler.Activity 33. Foot and Hand Reaction Times.Activity 34. Finding Speed and Acceleration Using a Vibrating Timer.Activity 35. Worksheet — Graph Hopscotching.Activity 36. Acceleration Due to Gravitational Force Using a Vibrating Timer.Activity 37. Worksheet — Going Up and Coming Down.Activity 38. Using a Liquid Level Accelerometer to Classify Motion on a Level Surface.Activity 39. Using a Liquid Level Accelerometer to Classify Motion on an Inclined Plane.Activity 40. Using a Liquid Level Accelerometer to Classify Circular Motion.Activity 41. Using a Liquid Level Accelerometer to Classify Simple Harmonic Motion.Activity 42. Kinematics of a Student — Acceleration.Activity 43. Differentiating Among Position, Velocity, & Acceleration.Activity 44. Signs for Our Times (A Line Dance).Activity 45. Worksheet — Graphs with Direction.Activity 46. An Acceleration Song (First Movement!).Activity 47. The “Racetrack” Game.Activity 48. Yellow Light Problem.Activity 49. Constant Acceleration (Whiteboard Problem).
Distance Measurement by Triangulation
Authors: Kallard T.
Published: November 2020

The laser is set up on a sturdy table. The beam is directed at a distant object or at a spot O marked on a wall.
Laser Optical Plummet
Authors: Kallard T.
Published: November 2020

A collimated He-Ne laser beam gives a natural visible reference line for any type of alignment survey.
“Double-Spot” Technique for Measuring Small Wedge Angles
Authors: Kallard T.
Published: November 2020

One of the applications for the optical arrangement shown in Fig. 78 is the measurement of very small wedge angles in optical flats. The technique involves measuring the angular separation between the beams reflected from the front and back surfaces of the flat.
The Luminous Fountain
Authors: Kallard T.
Published: November 2020

In order for total reflection to take place the light at the interface must originate in the medium of greater optical density. In the case of air and water total reflection can take place only when the source of light is inside the water. Figure 85 shows the technique to make the water stream appear luminous.
Demonstrating the Penetration of Laser Light Beyond a Totally Reflecting Interface
Authors: Kallard T.
Published: November 2020

The penetration of light beyond a totally reflecting interface can be demonstrated as follows: A prism and lens assembly is set to form a variable thickness airgap. The plane surface of a plano-convex lens (borrowed from the Newton’s rings apparatus) is optically coupled to the hypotenuse of a 90-degree prism (P2) using silicone grease (such as Dow Corning 20-057 Optical Coupling Compound). The convex surface is held lightly against the hypotenuse of the other 90-degree prism (P1). A gap is formed between the prisms which varies gradually from zero thickness in the center to many times the wavelength of light. Figure 87 shows the arrangement.
“Sliding Lens” Type Rangefinder
Authors: Kallard T.
Published: November 2020

Two equally weak lenses, one positive and one negative, form a zero-power lens combination which functions as a variable wedge through the lateral translation of one lens with respect to the other.
Laser Stroboscope
Authors: Kallard T.
Published: November 2020

The function of a stroboscope is to make moving things appear to the eye to be standing still. Strobe action may be accomplished by mechanical, optical and lighting means. Electronic strobes accomplish stop-action by flashing a very short duration light pulse in synchronism with moving objects. If, for example, the object is rotating and the flash occurs at the same instant of rotation each time, the object appears to the eye to be standing still.
Measurement of the Speed of Light
Authors: Kallard T.
Published: November 2020

Since light can travel about seven and half times around the earth in one second, measurements of this speed in the laboratory have been difficult and expensive.
Lens-Pinhole Spatial Filter
Authors: Kallard T.
Published: November 2020

In many experiments a clean, uncluttered laser beam is required for the recording or the observation of the fine details of interference and diffraction patterns. This is especially important for the needs of holography and optical data processing.
Measuring the Concentration of Colloidal Solutions or the Dirt Content of Water
Authors: Kallard T.
Published: November 2020

First a simple apparatus is described for measuring the concentration of a colloidal solution.

As shown in Fig. 106, the direct laser beam is incident on the colloidal solution (C) within the sample cell (Sc) made of glass. A ray shielding layer is formed on the surface of a lens (L). At the center portion of the ray shielding layer a small circular aperture (1) about the diameter of the laser beam, and a ring shaped thin slit (2) concentrically surrounding the center aperture are provided. A photo-detector (PD1) is provided on the axis of the direct laser beam, and a similar photo-detector (PD2) is provided at the imaging position of the solution (C). The outputs of these light sensitive elements are amplified (Amp) and fed to a ratio meter (M) such as a potentiometer type or wattmeter type device.
Optics Experiments with Liquid Crystals
Authors: Kallard T.
Published: November 2020

Liquid crystals were first identified at least ninety years ago, but it has been only during the last fifteen, or so, years that their unique physical properties and technical applications received any real attention.
The Twisted Nematic Effect
Authors: Kallard T.
Published: November 2020

This electro-optical effect in twisted nematic liquid crystals was discovered by Schadt and Helfrich. Twisted NLC cells produce high contrast, exhibit low threshold potentials, driving voltages of 2-5 volts, and power consumptions of 1-50 μW/cm2.
Thin Film Interference Using an Air Wedge
Authors: Kallard T.
Published: November 2020

Fizeau fringes result from essentially two beam interference occurring near a thin layer. Figure 156 illustrates this effect for a very thin “air wedge” between two glass plates.
Method and Procedure for Eye Testing with Laser Speckle
Authors: Kallard T.
Published: November 2020

An expanded laser beam is projected on a diffusing screen and thereby a visual pattern (speckle) is produced. If relative movement between an observer and the diffusing screen is provided, the perceived movement of the speckle pattern is an indication of the observer’s visual condition. The optical setup (Fig. 184) consists of a low-power Ne-Ne laser, a spatial filter to “clean” and expand the beam, and a means for diffusing the laser beam.
Laser Doppler Velocimetry
Authors: Kallard T.
Published: November 2020

The previous exercise was performed with a Michelson interferometer assembly. The loudspeaker emitted a low ‘rumble’ when mirror M1 was moved slowly, and an ever higher Doppler ‘whistle’ when faster and faster mirror movement was used. When the mirror was moved too rapidly, the signal became too high in frequency to be heard. This demonstrated the excellent velocity resolution of the Laser Doppler Radar, which is directly proportional to the carrier frequency, f. If we know the velocity of the mirror and match the beat frequency (Δf = Doppler frequency change) on a calibrated signal generator, we can obtain a fairly close approximation for the wavelength of the laser light (λ = 2v/Δf).
Making Photographic Diffraction Apertures and Masks
Authors: Kallard T.
Published: November 2020

Diffraction with visible light produces some beautiful patterns. Any sort of aperture will produce a diffraction pattern. Good apertures of various shapes can be made for qualitative and quantitative work by preparing a black-on-white master, photographically reducing its size, and then using the film negative (transparency) itself as the diffraction target.
Fresnel Diffraction Experiments
Authors: Kallard T.
Published: November 2020

The theory of Fresnel diffraction can be found in almost any textbook on optics. By using a low-power He-Ne laser it is also possible not only to observe Fresnel diffraction visually but also to study, experimentally, the intensity distribution in the Fresnel diffraction pattern of various apertures and obstacles.
Electrically Controllable Diffraction Grating
Authors: Kallard T.
Published: November 2020

R. Williams discovered in 1963 that application of an electric field to a thin layer of nematic liquid crystal (NLC) causes the formation of a lattice of cylindrical lenses within the liquid crystal material. For small a.c. potentials (5-10 volts) the minute deformation takes place regardless of whether the layer was originally of homogeneous or homeotropic alignment. A system of largely parallel striations is observed under a polarizing microscope. The line textures are called Williams domains after their discoverer. The stationary pattern usually gives way to turbulence at higher voltages, thus producing dynamic light scattering. The far-field diffraction pattern of light transmitted through these domains is similar to that from a phase grating. The diffraction pattern consists of equally spaced fringes.
Interferometric Method of Producing Optical Diffraction Gratings
Authors: Kallard T.
Published: November 2020

Interferograms as well as holograms are recordings of the interference pattern created by an object wave and a reference wave.
Experiments in Magnetism
Authors: Edge R. D.
Published: November 2020

Additional equipment is needed to perform experiments in magnetism, specifically a magnet! Cheap magnets can be obtained at any dime store, and such magnets can be used for the experiments below. The most suitable magnet, however, is one of the chubby alnico type, and a small bar magnet is probably best. For a class, the small cylinder magnets (2/3″ diameter), or even the break-off magnets sold by the Edmund Co. of Barrington, N. J. 08007, are quite suitable. The cylinder magnets cost about 8 for $2.50.
Technology Use
Authors: McCullough Jodi , McCullough Roy
Published: November 2020

American Association of Physics Teachers

One Physics Ellipse

College Park, MD 20740-3845

301-209-3300; Fax: 301-209-0845

Toys in Space, VT-3 1987

NASA Teacher Resource Center (http://education.nasa.gov/educators.html)
Index of Suppliers
Authors: McCullough Jodi , McCullough Roy
Published: November 2020

American Association of Physics TeachersOne Physics EllipseCollege Park, MD 20740301-209-3300www.aapt.org
Physics is Physics
Authors: Richtmyer F. K.
Published: November 2020

Perhaps I can best elucidate the rather cryptic title of this paper by quoting a remark of the late Professor G. W. Jones, Professor of Mathematics at Cornell University from 1877 to 1907 and one of the best teachers who ever occupied a professorial chair. It is told that an embryo teacher, taking one of Professor Jones’ courses, once asked him: “What must one do to become a successful teacher of mathematics?”; to which Jones replied: “To become a successful teacher of mathematics one must acquire a thorough knowledge of mathematics.”
The Opportunity of the Physics Teacher
Authors: Millikan Robert A.
Published: November 2020

It will generally be agreed that physics is the most fundamental of the sciences, that some knowledge of it underlies them all and is therefore their indispensable prerequisite. For this reason alone the job of the teacher of physics takes on unusual significance. But from my point of view it is much more vital in the present stage of development of the United States than most physics teachers themselves realize. The main purpose of this paper is to point out why.
Philip Morrison: Oersted Medalist for 1964
Authors: Parker Vincent E.
Published: November 2020

Recipient of the 1964 Oersted Medal for Notable Contribution to the Teaching of Physics.
The Evolution of Physics Teaching
Authors: Strassenburg Arnold A.
Published: November 2020

I wonder how many of you are familiar with the work of “The Committee on the Ideal Undergraduate Curriculum.” This committee published the following statement describing its preliminary deliberations.
Force Particle – Inertia
Authors:   NASA and AAPT
Published: November 2020

Determine the relationship between air drag and terminal velocity.
F = ma Contests
Authors: Kisačanin Branislav , Zhang Eric K.
Published: November 2020

This book presents clear and detailed solutions to all problems from the annual F=ma contest hosted by the American Association of Physics Teachers (AAPT) between 2011 and 2019. The competition is the precursor to the USAPhO (United States National Physics Olympiad) and the IPhO (International Physics Olympiad).

F = ma Contests: 2011-2019 Solutions Manual bridges a significant gap in existing literature for competition preparation and is a great resource for students preparing for physics exams and competitions.
Year 2013 F=ma Contest
Authors: Kisačanin Branislav , Zhang Eric K.
Published: November 2020

This chapter contains year 2013 F = ma exam problems and solutions.
Year 2015 F=ma Contest
Authors: Kisačanin Branislav , Zhang Eric K.
Published: November 2020

This chapter contains year 2015 F = ma Contest problems and solutions.
Year 2019 F=ma Contest
Authors: Kisačanin Branislav , Zhang Eric K.
Published: November 2020

In 2019, two F = ma exams were offered, Exam A and Exam B. This chapter contains problems and solutions for both exams.
What does it mean to be
Authors: Borrelle Stephanie B. , Koch Jonathan B. , MacKenzie Caitlin McDonough , Ingeman Kurt E. , McGill Bonnie M. , Lambert Max R. , Belasen Anat M. , Dudney Joan , Chang Charlotte H. , Teffer Amy K. , Wu Grace C.
Published: November 2020

Indigenous knowledge is a multilayered knowledge system that can effectively manage global ecosystem and biodiversity conservation. Conservation is an applied discipline with the goal of preserving the world’s biodiversity and ecosystems. However, settler–coloniser conservation practices often fail to fully examine how settler–coloniser epistemologies are centred at the expense of Indigenous conservation praxis. Evaluating how conservation practices outside of an Indigenous lens can become more inclusive and just is a critical area for research and reflection. We draw on our own experiences as early-career researchers working towards anticolonial, just and inclusive approaches to conservation science and practice by discussing what it means to be for a Place. We believe that a non-Indigenous conservationist who is for a Place advocates for inclusive stewardship with Indigenous Peoples and other marginalised communities to conserve species and ecosystems and the connections that bind communities to their landscapes. As an example of how settler–coloniser conservation practitioners can be for a Place, we discuss writing a policy statement in 2019 on behalf of the Society for Conservation Biology opposing the construction of the Thirty Meter Telescope on the summit of Mauna Kea, Hawai‘i. We describe the thought process behind our policy statement and provide examples of other actions for conservation researchers and practitioners working to be for a Place. We aim to provide our colleagues, particularly those trained in settler–coloniser conservation practices, an opportunity to identify more just practices for the Places we aspire to conserve.
Nebkhas play important roles in desertification control and biodiversity protection in arid and semi-arid regions of China
Authors: Luo Weicheng , Zhao Wenzhi , Liu Bing , Zhou Hai
Published: November 2020

Nebkhas are isolated mounds vegetated with burial-tolerant desert plants that trap windborne sediment within their canopies. Nebkhas are critical to desertification control and biodiversity protection of oases in arid and semi-arid regions of China, as they (ⅰ) trap windborne sediments and ensure oasis security; (ⅱ) as “fertile islands,” nebkhas can trap and provide a suitable micro-environment for seeds, birds, and small soil animals, and increase biodiversity; (ⅲ) increase the soil surface roughness and significantly reduce soil erosion following heavy rain. However, the establishment of sand-fixing vegetation and over-grazing significantly limits the development and accelerate the degradation of nebkhas, threatening oasis ecosystems. We provide background and recommendations for protective measures for nebkha landscapes in arid and semi-arid areas of China to aid managers in oasis protection.
Impacts of close-to-nature management on the stand states of Masson pine forests
Authors: Chai Zongzheng , Tan Wei
Published: November 2020

Introduction:
Research on the effect of close-to-nature management (CTNM) on stand states and dynamics of forests is crucial for the evaluation of CTNM implemented and sustainable development of forestry.

Outcomes:
We analyzed and compared the stand states and dynamics of Masson pine (
Pinus massoniana
) plantations in the young, middle-aged, and near-mature stages under CTNM eight years after selective cutting and unmanaged control. Both paired-sample T-tests and RDA ordination results demonstrated that the overall stand states with CTNM were superior to the control treatment in all three stages. The interaction of the CTNM and stand age significantly affected The Shannon-Wiener index of diameter class and regeneration density.

Discussion and Conclusion:
CTNM and stand age jointly affected the stand state of forests and CTNM accelerated the forest development, which promoted an increase in the heterogeneity of stand parameters and shortened the formation time of a target stand. Greater tree size differentiation and adequate regeneration are particularly important aspects for improving the quality of Masson pineforests during the management processes.
Conversion coefficients from total air kerma to the newly proposed ICRU/ICRP operational quantities for radiation protection for photon reference radiation qualities
Authors: Behrens Rolf , Otto Thomas
Published: November 2020

The International Commission on Radiation Units and Measurements (ICRU) has recently proposed a set of new operational quantities for radiation protection. ICRU supplied conversion coefficients for mono-energetic photons but not for photon reference radiation qualities defined by the International Organization for Standardization (ISO) in ISO 4037 and by the International Electrotechnical Commission (IEC) in IEC 61267. Therefore, in this work, conversion coefficients from total air kerma to the newly proposed operational quantities are averaged for photon reference radiation qualities. Also, parameters necessary to determine the influence of the air density on the conversion coefficients are determined. Finally, the impact of the newly proposed quantities upon the response of dosemeters is investigated.
Quantifying changes in size of arrhythmic photoplethysmography waveforms during a Valsalva maneuver for assessing cardiac filling pressure
Authors: Silber Harry A , Win Theingi Tiffany , Monti Jennifer , Galiatsatos Panagis
Published: November 2020

Objective: We previously showed that the change in amplitude of a finger photoplethysmography waveform during the Valsalva maneuver reflects cardiac filling pressure. However, the automated determination of peaks and valleys to calculate amplitude is limited in significant arrhythmias such as atrial fibrillation and premature ventricular complexes, which are common in heart failure. The purpose of this study was to assess the change in size of the waveform by calculating the change in root mean square (RMS) of the signal, thereby utilizing the entire cardiac cycle, and to compare it to change in size of peak-to-valley amplitude. Approach: We compared the two approaches in signals obtained from participants of a prior study who were tested prior to a clinically indicated cardiac catheterization. Correlation between the two methods was assessed in cases without, and then with, significant arrhythmias including atrial fibrillation or premature ventricular complexes. Main results: Calculations from the two methods of peak-valley amplitude and RMS were highly correlated with each other in signals without (0.99, p < 0.0001, n = 252) and with significant arrhythmias (0.90, p < 0.0001, n = 34). Significance: RMS analysis of photoplethysmography signal size during the Valsalva maneuver is highly correlated with the method of analyzing changes in peak-valley amplitude, but does not rely on identifying peaks and valleys. The RMS method may be a more robust automated method of assessing cardiac filling pressure in patients with significant arrhythmias.
Lab-on-CMOS — an in-vitro diagnostic (IVD) tool for a healthier society
Authors: Mak Pui-In
Published: November 2020

Towards a sustainable healthcare system, the clinical-grade diagnostic platform should be decentralized into low-cost consumer-grade handheld devices, for broadly and early disease screening and diagnosis. The joint advancement of CMOS biosensors and signal-processing capability has recently transformed bulky laboratory instruments into handheld devices, leading to cost, size and weight reduction by orders of magnitude. This article gives a glimpse of the lab-on-CMOS in-vitro diagnostic (IVD) tools for point-of-care applications.
A survey of high-speed high-resolution current steering DACs
Authors: Li Xing , Zhou Lei
Published: November 2020

Digital to analog converters (DAC) play an important role as a bridge connecting the analog world and the digital world. With the rapid development of wireless communication, wideband digital radar, and other emerging technologies, better performing high-speed high-resolution DACs are required. In those applications, signal bandwidth and high-frequency linearity often limited by data converters are the bottleneck of the system. This article reviews the state-of-the-art technologies of high-speed and high-resolution DACs reported in recent years. Comparisons are made between different architectures, circuit implementations and calibration techniques along with the figure of merit (FoM) results.
Analysis of cerebral electrical propagation generated by deep brain stimulation using finite elements
Authors: Devia D M , Mesa F , Ospina R
Published: November 2020

The surgical intervention called deep brain stimulation, is a stereotactic surgery that allows the control of some motor functions in the human body. For its execution it is necessary to make use of software engineering and an understanding of the operation and electrical activation in the brain. Based on the finite element method, this document will provide a solution to the Laplace differential equation that models the electrical potential generated during deep brain stimulation. To achieve this objective, we will initially present the theoretical foundations of the finite element method that include the approximation of Galerkin and the Max Milgram and Poincaré theorems; then assuming that the model of the human head is isotropic and uniform, the brain regions will be modeled with the characteristics of the environment (external skin of the skull, skull and brain) in such a way that the attenuation, direction and value of the potential a can be visualized as it changes material and moves along the surfaces that make up the human head model. The simulations obtained using the finite element method allowed determining which areas of the brain are involved by the interaction of potential sources, observing that bioelectric sources originate electrochemical activity in brain cells that are inactive in such a way that they generate controlled movements in the human body.
Overall heat transfer coefficient optimization in a spiral-plate heat exchanger
Authors: Rodriguez-Cabal M A , Arias Londoño A , Ardila-Marin J G , Grisales-Noreña L F , Castro-Vargas A
Published: November 2020

Heat exchangers are widely used in the industry to allow the heat transfer between two fluids. For that reason, correctly sizing said devices poses a design problem in order to guarantee the efficiency and appropriate conditions of the equipment and the processes. In this paper, the geometry of a spiral-plate heat exchanger is optimized by means of a particle swarm optimization algorithm, whose objective function is the maximization of the overall heat transfer coefficient. The process variables considered in the model were channel spacing, spiral length, spiral width, and wall thickness. The mathematical model and the particle swarm optimization were programmed in Matlab®, where the parameters and the constraints were defined, limiting the pressure drop and guaranteeing the heat transfer required for a study case taken from Minton’s work. In this study, the overall heat transfer coefficient was increased by 12.73% in comparison with the original design.
Modelling of the response of the generators to the automatic generation control commands under communication protocols based on the international standard
Authors: Molina J E , Holguin M , Rivas-Trujillo E
Published: November 2020

The frequency of an electrical power system is controlled by generators doing primary frequency regulation, which stands for maintaining the stability and reliability in short times and secondary frequency regulation, also known as Automatic Generation Control, which its main goal is to maintain the frequency in a set-point. This last is done remotely from the control centre of an electric power system operator in most cases, and to carry it out supervisory control and data acquisition -automatic generation control- energy management system. These systems are used that make use of current international standards of the International Electrotechnical Commission that adapt in any case to many supervision and control mechanisms. Using those standards supposes the use of a range of available options; particularly, the commands used to control electric power generators fall into 2 possible options, and to evaluate responses under disturbances, a study of the modelling of generators under automatic generation control becomes necessary. A study of the response in closed loop control of automatic generation control is discussed to determine its models under different scenarios. Then, this is the input to determine responses to simulated deviations on the commands due to known failures or disturbances.
Estimation of the parameters of the particular solution of a partial differential equation through Cramer Rao
Authors: Mesa F , Devia D M , Ospina R
Published: November 2020

The parameter estimation task is given by statistical exploration of probability density functions. The volume of samples and characteristics of a database is an advantage to solve the problem of parameter estimation but finding a function that models the behavior of a database or its distribution is complex and without this step it is not possible to use advanced statistical techniques. This document solves the problem of parameter estimation of a particular solution of a partial differential diffusion equation, the parameters found are suitable for the distribution in a domain of the amount of concentration of a material by means of the Cramer Rao limit and the value expected coefficients. With the non-linear technique used to find the optimal value of the constants, it was possible to observe the convergence of the coefficients at a given value thanks to the performance of this technique and the intrinsic characteristics of the database combined with a Gaussian normal distribution.
Trans-complexity: a management fad or a mathematical construct
Authors: Bravo A , Salazar-Torres J , Madriz D , Vergel-Ortega M
Published: November 2020

Trans–complex organizations concept has been introduced in the management science, even becoming an object of study. In the global context, definitions, concepts, research and philosophical or practical proposals have emerged for the understanding of organizations from a trans-complex perspective. In this work, a critical position of trans-complexity is presented as a historical discovery that associates a new characterization of phenomena: for example, in exchange for trans–complex organizations, a trans-complex epistemic vision of social organizations is proposed. Thus, the trans-complexity is ratified not as a quality, but as a requirement of epistemic order of scientific research. From this perspective, that complex organization can be explained through elements such as uncertainty, chaos and self-organization, with an epistemological explanation of systems theory, decision theory and dynamic systems theory. This paper shows the trans-complexity more than a management fad, an analysis model or a management topic, as an element to be incorporated by researchers in the construction of theoretical frameworks and methodical designs of their researches in order to purpose significant contributions to science, and to the organization itself, based on such important mathematical theories.
Microstructure and corrosion resistance of in-suit coating on copper alloy using laser shock melt injection of fine-CeO2 particles
Authors: Wang Hongyu , Zhai Xuqiang , Sun Yongyi
Published: November 2020

In order to improve the marine corrosion resistance of the copper alloy, the method of synergistic modification was introduced to prepare the in situ coating on the surface of HSn62-1 by laser shock melt injection of fine-CeO2 particles. The micrograph and microstructure of the Hsn62-1, in situ coating, and the laser-treated sample were investigated in contrast. Besides, the electrochemical corrosion resistance of the three specimens in 3.5% NaCl solution was studied. The results demonstrated that the in situ coating had good compactness and no apparent defects. The upper part of the in-suit coating was mainly cellular solidification microstructure, while the microstructure in the middle and lower part was coarse dendrite. Compared with Hsn62-1 copper alloy, the corrosion resistance of the laser-treated sample and the in-suit coating were improved, which proved that the synergistic modification of laser and rare earth could improve the corrosion resistance of the copper alloy. The analysis indicated that the rare earth elements in the in-suit coating would undergo hydrolysis reaction to form the dense rare-earth hydroxide in an ‘island growth’ way, which effectively prevented the invasion of corrosion ions.
The Effectiveness of Non-Benzodiazepine, Non-Barbiturate Medications for Alcohol Withdrawal Syndrome: A Rapid Systematic Review
Authors: Ghosh Abhishek , Mahintamani Tathagata , Choudhury Shinjini , Sharma Nidhi , Das Sauvik
Published: November 2020

Aim

There are potential clinical, ethical and legal concerns with overdosing benzodiazepines (or barbiturates) for the treatment of moderate to severe alcohol withdrawal symptoms (AWS) through telemedicine or ambulatory outpatients. A rapid systematic review to (a) qualitatively summarize the non-benzodiazepine treatment alternatives, (b) evaluate the quality of evidence for the same to effectively manage moderate to severe AWS.

Methods

We conducted searches on PubMed (January 1990 to 31 March 2020), Cochrane Central Register of Controlled Trials, and Google Scholar. We selected the English language randomized controlled trials (RCTs) assessing the efficacy and adverse effects of non-benzodiazepine and non-barbiturate medications among adults with a diagnosis of AWS. Data extraction was done in a predefined format. Risk of bias (RoB) assessment and qualitative synthesis of evidence was done with the RoB2 tool and Grading of Recommendations Assessment, Development, and Evaluation (GRADE) proGDT.

Results

Thirty-four RCTs were included. Gabapentin (n = 6), carbamazepine (n = 5), baclofen (n = 5), valproate (n = 3), clonidine/lofexidine (n = 3) and acamprosate (n = 2) had more than one trial with a particular comparison group. Four studies were found to have a low ROB. The GRADE evidence summary showed gabapentin had a ‘moderate’ level of evidence against standard benzodiazepine treatments for reducing the severity of AWS. The level of certainty was ‘low’ for carbamazepine, baclofen and valproate and ‘very low’ for acamprosate and clonidine/lofexidine. Reported adverse events between these alternative medications and benzodiazepines or placebo were generally unremarkable.

Conclusions

Although benzodiazepines remain the treatment of choice for AWS, during particular circumstances, gabapentin could be an alternative although like benzodiazepines is not without risk when used in the community. Future RCTs must aim to improve upon the quality of evidence.
Providing Opportunities for Patients to Say More about Their Pain without Overtly Asking: A Conversation Analysis of Doctors Repeating Patient Answers in Palliative Care Pain Assessment
Authors: Jenkins Laura , Parry Ruth , Pino Marco
Published: November 2020

As the main symptom in palliative care, pain requires careful assessment. Repeating patient answers is one recommended communication technique for helping convey to patients that they have been heard, and to encourage them to say more. We examined 23 episodes where experienced doctors repeat patients' answers with mirrored rhythm and downward-final intonation, captured in pain assessments video-recorded in 37 consultations in a large UK hospice. Using conversation analysis, our aim was to determine whether or not the repeats invite additional talk, and if so, how they do so. Our findings reveal lexical and prosodic features of doctors’ repeated pain answers that signal completion of the sequence. At the same time, because the patient has greater epistemic access to their own pain, a repeat can also invite confirmation or disconfirmation. The patients in our data sometimes—but not always—respond to the repeat with confirmation or further talk. We conclude that repeating patient answers with mirrored rhythm and downward-final intonation provides a no-obligation opportunity for patient-led confirmation, disconfirmation, or expansion of pain descriptions, particularly when the pain matter is new, revised, or has been problematic to report.
Magnetic resonance imaging biomarkers of cerebrospinal fluid tracer dynamics
in idiopathic normal pressure hydrocephalus
Authors: Eide Per Kristian , Pripp Are H , Ringstad Geir
Published: November 2020

Disturbed clearance of toxic metabolites from the brain via cerebrospinal fluid is emerging as an important mechanism behind dementia and neurodegeneration. To this end, magnetic resonance imaging work-up of dementia diseases is largely focused on anatomical derangements of the brain. This study explores magnetic resonance imaging biomarkers of cerebrospinal fluid tracer dynamics in patients with the dementia subtype idiopathic normal pressure hydrocephalus and a cohort of reference subjects. All study participants underwent multi-phase magnetic resonance imaging up to 48 h after intrathecal administration of the contrast agent gadobutrol (0.5 ml, 1 mmol/ml), serving as cerebrospinal fluid tracer. Imaging biomarkers of cerebrospinal fluid tracer dynamics (i.e. ventricular reflux grades 0–4 and clearance) were compared with anatomical magnetic resonance imaging biomarkers of cerebrospinal fluid space anatomy (Evans’ index, callosal angle and disproportional enlargement of subarachnoid spaces hydrocephalus) and neurodegeneration (Schelten’s medial temporal atrophy scores, Fazeka’s scores and entorhinal cortex thickness). The imaging scores were also related to a pulsatile intracranial pressure score indicative of intracranial compliance. In shunt-responsive idiopathic normal pressure hydrocephalus, the imaging biomarkers demonstrated significantly altered cerebrospinal fluid tracer dynamics (ventricular reflux grades 3–4 and reduced clearance of tracer), deranged cerebrospinal fluid space anatomy and pronounced neurodegeneration. The altered MRI biomarkers were accompanied by pressure indices of impaired intracranial compliance. In conclusion, we present novel magnetic resonance imaging biomarkers characterizing idiopathic normal pressure hydrocephalus pathophysiology, namely measures of cerebrospinal fluid molecular redistribution and clearance, which add information to traditional imaging scores of cerebrospinal fluid space anatomy and neurodegeneration.
The dirty little secret of urate-lowering therapy: useless to stop chronic kidney disease progression and may increase mortality
Authors: Gonzalez-Martin Guillermo , Cano Jaime , Carriazo Sol , Kanbay Mehmet , Perez-Gomez Maria Vanessa , Fernandez-Prado Raul , Ortiz Alberto
Published: November 2020

Hyperuricaemia is frequent in chronic kidney disease (CKD). Observational studies have shown an association with adverse outcomes and acquired hyperuricaemia (meaning serum urate levels as low as 1.0 mg/dL) in animal models induces kidney injury. This evidence does not justify the widespread use of urate-lowering drugs for asymptomatic hyperuricaemia in CKD. However, promising results from small, open-label studies led some physicians to prescribe urate-lowering drugs to slow CKD progression. Two recent, large, placebo-controlled trials (CKD-FIX and PERL) showed no benefit from urate lowering with allopurinol on the primary endpoint of CKD progression, confirming prior negative results. Despite these negative findings, it was still argued that the study population could be optimized by enrolling younger non-proteinuric CKD patients with better preserved glomerular filtration rate (GFR). However, in these low-risk patients, GFR may be stable under placebo conditions. Additionally, the increased mortality trends already identified in gout trials of urate-lowering therapy were also observed in CKD-FIX and PERL, sending a strong safety signal: 21/449 (4.7%) and 10/444 (2.2%) patients died in the combined allopurinol and placebo groups, respectively [chi-squared P-value 0.048; relative risk 2.07 (95% CI 0.98–4.34); P = 0.06]. Given the absent evidence of benefit in multiple clinical trials and the potentially serious safety issues, the clear message should be that urate-lowering therapy should not be prescribed for the indication of slowing CKD progression. Additionally, regulatory agencies should urgently reassess the safety of chronic prescription of urate-lowering drugs for any indication.
Assisting Elementary School Personnel to Better Serve and Support Immigrant and Latine Heritage Children
Authors: Garcia Martha Lucia
Published: November 2020

A 2019 United Nations (UN) report declared the need for educational support by teachers for immigrant and refugee children across the world. These children directly or indirectly experience trauma throughout the migration process, which manifests in different aspects of their development. At the educational level, trauma can affect children’s ability to concentrate and learn. Trainings on trauma-informed teaching may not include the specific forms of trauma experienced by immigrant children during stages of migration or the impact of trauma caused by war, or the hatred that leads to genocide. This makes invisible the extreme, repeated, or varied traumatic events that may have been lived by children escaping from Central America’s Northern Triangle, which includes El Salvador, Guatemala, and Honduras. Teachers working with immigrant children need this information to be able to adapt their lessons and teaching style to meet children’s needs. The study discussed in this article attempts to address the reactions of trauma and fear on immigrant children by training and supporting teachers and staff in an elementary school who work with “Latine” children. This article presents a tested training module that responds to the call by the UN to assist immigrant children through the training of school personnel.
EACVI survey on the management of patients with patent foramen ovale and cryptogenic stroke
Authors: D'Andrea Antonello , Dweck Marc R , Holte Espen , Fontes-Carvalho Ricardo , Cameli Matteo , Aboumarie Hatem Soliman , Diener Hans Christoph , Haugaa Kristina H
Published: November 2020

Aims 

The European Association of Cardiovascular Imaging (EACVI) Scientific Initiatives Committee performed a global survey to evaluate the current practice for the assessment and management of patients with suspected patent foramen ovale (PFO) and cryptogenic stroke.

Methods and results 

In total, 79 imaging centres from 34 countries across the world responded to the survey, which comprised 17 questions. Most non-invasive investigations for PFO were widely available in the responding centres, with the exception of transcranial colour Doppler which was only available in 70% of sites, and most commonly performed by neurologists. Standard transthoracic echocardiography, with or without bubbles, was considered the first-level test for suspected PFO in the majority of the centres, whereas transoesophageal echocardiography was an excellent second-level modality. Most centres would rule out atrial fibrillation (AF) as a source of embolism in all patients with cryptogenic stroke (63%), with the remainder reserving investigation for patients with multiple AF risk factors (33%). Cardiac magnetic resonance was the preferred tool for identifying other unusual aetiologies, like cardiac masses or thrombi. After PFO closure, there was variation in the use of antiplatelet therapy: a quarter recommended treatment for life, while only 12% recommended 5 years as stipulated in the guidelines (12%). Antibiotic prophylaxis prior to dental or endoscopic procedures was not recommended in 41% of centres, contrary to what the guidelines recommended.

Conclusion 

Our survey revealed a variable adherence to the current recommendations for the diagnosis and management of patients with cryptogenic stroke and PFO. Efforts should focus on optimizing and standardizing diagnostic tests and treatment of this condition.