bluuebunny/crossref_metadata_2025 huggingface dataset:
The Michelson Interferometer
Authors: Kallard T.
Published: November 2020

The Michelson interferometer is an optical apparatus which includes a beam splitter for dividing an input beam of light into two beams of approximately equal intensity. The two separated beams of light are made to traverse paths of differing optical lengths and are subsequently combined. If the optical path lengths do not differ by too large an amount, interference effects occur.
The Point-diffraction (“Smartt”) Interferometer
Authors: Kallard T.
Published: November 2020

The Point Diffraction Interferometer (PDI) was first described in 1972 by Dr. Raymond N. Smartt of the University of Massachusetts. The PDI is a simple but powerful interferometric system.
Demonstrations Illustrating Temporal and Spatial Coherence
Authors: Kallard T.
Published: November 2020

In many laser applications, such as interference and holography, the coherence properties of the laser are extremely important. The beam of light emitted by a laser can have the property of being almost completely coherent. In practice, light from a laser is not coherent. It is simply much more coherent than light from any other source. Just how much more coherent depends on the definition of the word “coherent.”
Dynamic Scattering Effect
Authors: Kallard T.
Published: November 2020

This electro-optical effect was discovered in 1918 by Y. Bjornstahl. It was first discussed in depth by Heilmeier and his co-workers in 1968.
Examining Vibrating Objects by Means of Laser Speckle
Authors: Kallard T.
Published: November 2020

With this simple method one can obtain data (visually or photographically) about the movement, or the state of rest, of various surface elements of a vibrating object to be examined.
Simple Optical System for Fraunhofer Diffraction Experiments
Authors: Kallard T.
Published: November 2020

When an aperture (or obstacle) is placed within the cross section of a beam of light and the transmitted light is observed on a screen, the resulting distribution of light is called a diffraction pattern. There are two basic forms of diffraction: Fresnel and Fraunhofer. If both source and observation screen are at a finite distance from the diffracting object, the pattern is called a Fresnel diffraction pattern (near-field diffraction). Under these conditions an image of the aperture (or obstacle) is projected onto the observation screen. The image is clearly recognizable despite some fringing around its periphery. If the observation screen is placed very far from the diffracting object, the pattern is called a Fraunhofer diffraction pattern (far-field diffraction). At a very great distance the projected pattern will bear little or no resemblance to the diffracting object. Moving the observation screen even further away will only change the size of the pattern but not its shape.
Diffraction Patterns
Authors: Kallard T.
Published: November 2020

The diffraction patterns shown below were recorded on Kodak Panatomic-X film. A 0.9 mW laser (Metrologic ML-968) was the light source. The Fresnel patterns were photographed with the setup shown in Fig. 213. The arrangement shown in Fig. 208 was used to photograph the Fraunhofer patterns. The film in the 35-mm single lens reflex camera took the place of the screen, W. Exposure times ranged from 1/60 to 1/250 second.
Measuring the Wavelength of Light with a Ruler
Authors: Kallard T.
Published: November 2020

Diffraction of light may be observed in common everyday objects. One such object is an LP phonograph record. The grooves act as a reflecting grating and good diffraction spectra can be observed on a nearby wall if a laser beam is bounced off the LP record at an oblique angle.
Diffraction Refractometer
Authors: Kallard T.
Published: November 2020

The wavelength of light can be measured easily by use of the diffraction grating. A laser, a fish tank and an inexpensive replica grating is all that is needed to calculate the wavelength of the laser light in air and in water. From the ratio of the two wavelengths the index of refraction of water can be obtained.
Spatial Filtering Experiments
Authors: Kallard T.
Published: November 2020

Spatial filtering is one of the most important tools for the optical processing of optical information. A simple but striking demonstration of the image-filtering operations can be performed with coherent optical filters as presented by A.B. Porter in 1906, to illustrate the Abbe theory of the microscope.
360° Holography
Authors: Kallard T.
Published: November 2020

When viewing planar holograms, it appears that one is looking through a window at the object. Thus, one can only view an object in a 10xl2.5 cm (4”x5”) hologram as if one were looking through a window of the same size as the film. The advantage of 360-degree holograms is that the ‘window’ wraps all the way around the object. T.H. Jeong was the first to describe cylindrical holography. Today there are commercial kits available (Metrologic No. 60-634) which not only include the optical parts but also vibration mounts, chemicals and the special 70-mm wide recording film. Figure 258 shows the arrangement for producing 360-degree holograms.
Producing Fourier Holograms
Authors: Kallard T.
Published: November 2020

Fresnel holograms refer to a photographic record describing the interference between a Fresnel diffraction pattern (arising from transmission through or reflection from the diffracting object) and an off-axis reference beam. Upon reconstruction these holograms give rise to twin images which are physically separated in space transverse to the optical axis.
Current Electricity
Authors: Edge R. D.
Published: November 2020

It is impossible to employ the same simple equipment for experiments in electricity as it is for mechanics, heat and light, for example.

The primary requirement is a source of D.C. Batteries are most commonly used, but are a poor idea, since, from one semester to the next, new batteries must be found, the old ones having died on the shelf. It follows, a power supply running off the 120V A.C. is much preferable.
Introduction for Group Leaders
Authors: McCullough Jodi , McCullough Roy
Published: November 2020

The literature is replete with testimonials to the enjoyment that both students and instructors feel when toys are used in the physics classroom. At American Association of Physics Teachers meetings, the sessions on toys are always well attended. Many instructors have run workshops on toys for elementary teachers. The Physics Teacher, a journal published by AAPT for instructors of introductory physics courses, contains articles as early as 1966 describing how various teachers have used toys in their classrooms and, as can be seen from the graph on page 1.2, the number of articles on physics toys has grown significantly during the past ten years.
Homework Questions
Authors: McCullough Jodi , McCullough Roy
Published: November 2020

1.1 — What happens to the speed of an object thrown into the air?

ANS.

The object slows down as it rises.
Basic Concept and Forms of Energy
Authors: Roeder John L.
Published: November 2020

Activity 1. Designing a Roller Coaster (Teacher’s Notes)

PROCESS SKILLS: Measure, Observe, Compare, Test, Explain
War Problems of the Physics Teacher
Authors: Compton Arthur H.
Published: November 2020

In presenting today the first Richtmyer Memorial Lecture we are doing honor to a physicist who was more than a physicist. He trained men who are now among the nation’s leaders. His teaching enabled his students to acquire the technic of exact thinking. He had that breadth of vision which helped both his students and his colleagues to understand the setting of their scientific labors and to form intelligent objectives as their goals. He thus helped to lay the foundation of a strong society.
New Frontiers
Authors: Dodge Homer L.
Published: November 2020

All who have given the Richtmyer Memorial Lectures have shared the feeling that they were dealing with matters that would be close to the heart of Floyd Karker Richtmyer (1881–1939). When one considers the range of subjects treated in these lectures and the variety of points of view represented, this means that Richtmyer was a many-sided man who touched physics on all of its principal frontiers. He was not one of the founders of the American Physical Society, but he had a part in the expansion of the interests of physicists that resulted in the formation of other societies concerned with physics. He was also one of the first to realize the dangers inherent in the multiplication of societies and the need for unification in the American Institute of Physics.
Quarter Century of Progress in the College Physics Laboratory
Authors: Overbeck C. J.
Published: November 2020

If you were to take from your bookshelf any one of the recently written college physics laboratory manuals and read the titles of the experiments you would find the following.
Remarks by Dr. Marsh W. White, February 2, 1956
Authors: White Marsh W.
Published: November 2020

This occasion is especially noteworthy in view of the historic significance of the Twenty-Fifth Anniversary of the founding of both the American Association of Physics Teachers and the American Institute of Physics. Just a quarter-century ago, on December 29, 1930, I had the pleasure of participating in that momentous luncheon conference in Cleveland, Ohio, when the AAPT was officially organized. A short time later, on January 27, 1932, the fledgling Association acquired equal status with the other physics societies in the plans for the work of the AIP, this Institute having been officially activated on May 3, 1931.
On Colleagues and Clients
Authors: Kirkpatrick Paul
Published: November 2020

Thank you, Professor Eaton and President Overbeck. I haven’t often been honored by a two-stage introduction and certainly never by one so eloquent, so specific, or so favorably biased. I think, ladies and gentlemen, I have never before been awarded a medal, either for heroism, good conduct, great achievement, or academic fortitude. The Oersted medal—at its best—calls for a measure of all four qualifications, and I have never thought of myself as a fit candidate for it. I have served the American Association of Physics Teachers in various capacities but wouldn’t think it right for the officers of the Association just to give prizes to each other.
Newton and the American political tradition
Authors: Arons A. B.
Published: November 2020

Students of intellectual history establish a clear line of connection from Newton and Locke through the philosophy of the Enlightenment and the evolution of deism to the American political tradition reflected in the Constitution and the Declaration of Independence. This paper briefly traces the historical sequence and indicates readily available sources (mostly in paperback) in which students and lecturers can find deeper background and additional detail.
Uniform Acceleration
Authors:   NASA and AAPT
Published: November 2020

Given the cruising speed of the plane, angle of descent, landing speed, and time until landing, compare the calculated angle of deflection to the actual measured angle of deflection.
Terminal Velocity
Authors:   NASA and AAPT
Published: November 2020

Identify the variables that influence the drag and time of fall on various objects.
Year 2011 F=ma Contest
Authors: Kisačanin Branislav , Zhang Eric K.
Published: November 2020

This chapter contains year 2011 F=ma exam problems and solutions.
Year 2014 F=ma Contest
Authors: Kisačanin Branislav , Zhang Eric K.
Published: November 2020

This chapter contains year 2014 F = ma exam problems and solutions.
Year 2017 F=ma Contest
Authors: Kisačanin Branislav , Zhang Eric K.
Published: November 2020

This chapter contains year 2017 F = ma exam problems and solutions.
Advances in neural networks and potential for their application to steel metallurgy
Authors: Smith J. L.
Published: November 2020

This review provides a timely exploration of several novel neural network (NN) architectures and learning methods, following a concise overview of the fundamentals of NNs and some important associated challenges. There are many benefits to using NNs, including deep learning models, in scientific research and, by understanding novel techniques better suited to certain applications, this benefit can be maximised. Finally, a few developed and emerging alternative learning paradigms are surveyed for their potential benefit to future research. The reviewed literature and accompanying discussion are of generic value well beyond steel metallurgy, and there is much to be gained from assessing methods used in other areas of materials science and further afield in order to apply them to steel metallurgy.
The Consideration of Indigenous Peoples in High Stakes Evaluations of Risk
Authors: Almond Madison F. E. , Cook Alana N. , Storey Jennifer E.
Published: November 2020

While Indigenous peoples account for a small portion of the Canadian population, they are overrepresented in the Canadian Criminal Justice System. Research and case law suggest culture should always be considered in violence risk assessments (VRAs), but it is unknown whether this recommendation is followed. The present study examined the role of Indigenous versus non-Indigenous culture in judicial opinions regarding evaluators’ VRA and expert witness testimony in Dangerous Offender and Long-Term Offender (DO/LTO) hearings under Canadian Law. 214 DO/LTO hearings from 2009-2016 where judges commented on VRAs submitted to the court were systematically identified via the Canadian Legal Information Institute database. Judicial comments were analyzed in cases with Indigenous and non-Indigenous defendants for discussions of culture and the prevalence of comments regarding qualities of the evaluator(s), qualities of the VRA(s) completed, and qualities of the evaluators’ expert testimony about the VRA. Judges considered culture meaningfully in 64% of Indigenous offenders’ cases. Discussion of VRA tools’ content was significantly more frequent in non-Indigenous cases; otherwise, frequency of non-cultural themes did not vary between case groups. Given the importance of considering culture in VRA, it is concerning that culture was considered in just over half of cases; improving this deficit is discussed.
Examining the policy-practice gap- The issue of crop burning induced Particulate Matter pollution in Northwest India
Authors: Kaushal Leena Ajit
Published: November 2020

The study examine the efficacy of government policy interventions initiated since 2014 to curb FCRB in NW Indian states and the related air pollution in Delhi-NCR during 2014-2019. The regression analysis suggests an increase in PM2.5 of ~69 µg/m3/1000 surge in fires. VIIRS retrieved data suggest an overall declining trend of ~1606 and ~4308 fire counts per year across NW states during October-November respectively. The monthly PM2.5 concentrations in New Delhi exhibits a decline of ~2.18 µg/m3 and ~5.17 µg/m3 per year over the same period. Despite an overall increase of ~17.6 % rice productivity, a noted decrease in fire activity over the period is an encouraging move, likely a result of some control imposed by authorities on FCRB. Owing to a significant ~35.5% rise in wheat productivity, data records rising trend in wheat residue burning activities in April (~1298/year) and May (~2402/year) but do not trigger extreme pollution due to difference in intensity of fires across harvesting seasons and relatively weak northwesterly wind direction.
Nevertheless, the overall high PM2.5 levels in October-November and April-May compared to NAAQS 24-hour average of 60µg/m3, disproves the overall efficacy of government policies to curb FCRB and related air pollution in IGP region.
Critical properties of symmetric nuclear matter in low-density regime using effective-relativistic mean field formalism
Authors: Parmar Vishal , Sharma M K , Patra S K
Published: November 2020

The effective field theory motivated relativistic mean-field (E-RMF) formalism is employed to study the equation of state (EoS) for the infinite symmetric nuclear matter (SNM) at finite temperature using the recently developed forces FSUGarnet, IOPB-I, G3, and the well known NL3 force parameter. The EoS is then used to estimate the critical temperature T
c, pressure P
c and density ρ
c of the SNM for the liquid–gas phase transition. As T
c is not a constrained parameter in both experiments and theoretical calculations, there is a large uncertainty around its value. Although, the critical parameters are correlated among themselves. It is revealed that vector self-coupling ζ
0 of used forces play determining role in EoS in finite temperature limit. Keeping the incompressibility in acceptable limit i.e. 240 ± 20 MeV, the lower value of ζ
0 gives a better result of T
c when compared to the several experimental data. The critical parameters however show weak correlation with the properties at saturation density at zero temperature. The compressibility factors calculated with these parameters are in agreement with the universal value of liquid–gas systems. Stability conditions are examined along with binodal and spinodal regions. Besides this, the thermodynamic properties like specific heat and latent heat are also worked out. We have carried out detailed consistency check of our calculations using critical exponents and standard scaling laws. All the exponents are well within the theoretical mean-field results.
Beam characterization and feasibility study for a small animal irradiation platform at clinical proton therapy facilities
Authors: Gerlach S , Pinto M , Kurichiyanil N , Grau C , Hérault J , Hillbrand M , Poulsen P R , Safai S , Schippers J M , Schwarz M , Søndergaard C S , Tommasino F , Verroi E , Vidal M , Yohannes I , Schreiber J , Parodi K
Published: November 2020

A deeper understanding of biological mechanisms to promote more efficient treatment strategies in proton therapy demands advances in preclinical radiation research. However this is often limited by insufficient availability of adequate infrastructures for precision image guided small animal proton irradiation. The project SIRMIO aims at filling this gap by developing a portable image-guided research platform for small animal irradiation, to be used at clinical facilities and allowing for a precision similar to a clinical treatment, when scaled down to the small animal size. This work investigates the achievable dosimetric properties of different lowest energy clinical proton therapy beams, manipulated by a dedicated portable beamline including active focusing after initial beam energy degradation and collimation. By measuring the lateral beam size in air close to the beam nozzle exit and the laterally integrated depth dose in water, an analytical beam model based on the beam parameters of the clinical beam at the Rinecker Proton Therapy Center was created for the lowest available clinical beam energy. The same approach was then applied to estimate the lowest energy beam model of different proton therapy facilities, Paul Scherrer Institute, Centre Antoine Lacassagne, Trento Proton Therapy Centre and the Danish Centre for Particle Therapy, based on their available beam commissioning data. This comparison indicated similar beam properties for all investigated sites, with emittance values of a few tens of mm·mrad. Finally, starting from these beam models, we simulated propagation through a novel beamline designed to manipulate the beam energy and size for precise small animal irradiation, and evaluated the resulting dosimetric properties in water. For all investigated initial clinical beams, similar dosimetric results suitable for small animal irradiation were found. This work supports the feasibility of the proposed SIRMIO beamline, promising suitable beam characteristics to allow for precise preclinical irradiation at clinical treatment facilities.
Error suppression techniques for energy-efficient high-resolution SAR ADCs
Authors: Liu Jiaxin , Tang Xiyuan , Shen Linxiao , Li Shaolan , Li Zhelu , Guo Wenjuan , Sun Nan
Published: November 2020

The successive approximation register (SAR) is one of the most energy-efficient analog-to-digital converter (ADC) architecture for medium-resolution applications. However, its high energy efficiency quickly diminishes when the target resolution increases. This is because a SAR ADC suffers from several major error source, including the sampling kT/C noise, the comparator noise, and the DAC mismatch. These errors are increasing hard to address in high-resolution SAR ADCs. This paper reviews recent advances on error suppression techniques for SAR ADCs, including the sampling kT/C noise reduction, the noise-shaping (NS) SAR, and the mismatch error shaping (MES). These techniques aim to boost the resolution of SAR ADCs while maintaining their superior energy efficiency.
A comparative study of digital low dropout regulators
Authors: Huang Mo , Lu Yan , Martins Rui P.
Published: November 2020

Granular power management in a power-efficient system on a chip (SoC) requires multiple integrated voltage regulators with a small area, process scalability, and low supply voltage. Conventional on-chip analog low-dropout regulators (ALDOs) can hardly meet these requirements, while digital LDOs (DLDOs) are good alternatives. However, the conventional DLDO, with synchronous control, has inherently slow transient response limited by the power-speed trade-off. Meanwhile, it has a poor power supply rejection (PSR), because the fully turned-on power switches in DLDO are vulnerable to power supply ripples. In this comparative study on DLDOs, first, we compare the pros and cons between ALDO and DLDO in general. Then, we summarize the recent DLDO advanced techniques for fast transient response and PSR enhancement. Finally, we discuss the design trends and possible directions of DLDO.
Optical frequency ratio of a 171Yb+ single-ion clock and a 87Sr lattice clock
Authors: Dörscher S , Huntemann N , Schwarz R , Lange R , Benkler E , Lipphardt B , Sterr U , Peik E , Lisdat C
Published: November 2020

We report direct measurements of the frequency ratio of the 642 THz

S

1
/
2

2

(

F
=
0

)

–

F

7
/
2

2

(

F
=
3

)

electric octupole transition in 171Yb+ and the 429 THz

S

0

1

–

P

0

3

transition in 87Sr. A series of 107 measurements has been performed at the Physikalisch-Technische Bundesanstalt between December 2012 and October 2019. Long-term variations of the ratio are larger than expected from the individual measurement uncertainties of few 10−17. The cause of these variations remains unknown. Even taking these into account, we find a fractional uncertainty of the frequency ratio of 2.5 × 10−17, which improves upon previous knowledge by one order of magnitude. The average frequency ratio is

ν

Y
b

+

/

ν

S
r

=
1.495

991

618

544

900

537

(

38

)

. This represents one of the most accurate measurements between two different atomic species to date.
Non-linear controller for Boost converter via extended linearization
Authors: Mesa F , González J R , Correa G
Published: November 2020

This document describes the extended linearization method for system control. The purpose of which is to determine a non-linear control signal in such a way that linearization of said signal around an operating point results in the approximate linear controller. When the approximate linear controller is obtained, a non-linear control signal is inferred from it, which allows the system to be controlled around the family of points associated with the initially established operating point. The importance of this type of control technique allows to analyze non-linear systems around the operating points with a wider margin than what could be done traditionally. its implementation on a converter is of great importance since electrical systems every day incorporate more elements of power electronics.
A spectral element method to compute approximations of the anisotropic diffusion operator with bidimensional tensor coefficient
Authors: Calderon-Barreto E A , Acosta-Minoli C A , Quiroga-Méndez J E
Published: November 2020

We derived a continuous Galerkin spectral element method to compute approximations of the anisotropic diffusion operator with the tensorial coefficient of order two. After writing the operator in the weak form, we calculated spatial integration using the Legendre base. Then, we applied three different methods for the solution of the associated linear system: The Lower-Upper factorization, the biconjugate gradient method and the biconjugate gradient stabilized method with the Richardson preconditioner. To validate the algorithm, we present a convergence study for the Poisson equation when varying the functions of the tensor coefficient. Results show how the algorithm can be used to construct solvers for more complex problems like the anisotropic diffusion-reaction equation.
Influence of COVID-19 confinement on physics learning in engineering and science students
Authors: Mendoza-Lizcano S M , Palacios Alvarado W , Medina Delgado B
Published: November 2020

Due to the global alert about the risk of contagion and propagation of Covid-19, a situation that has changed in the educational processes, this has forced the system to migrate towards a more dynamic and connected model of teaching and learning, which has allowed not to interrupt and to continue with the training processes, in a remote and assisted way. In this research, the profile of the engineering and science student is analyzed, and its relationship with the learning of physics in this crisis. For this purpose, the technique of simple random sampling of a certain population was applied, a research instrument was designed and validated by pairs of experts, its reliability was established based on Cronbach’s Alpha test, and the instrument was applied to 354 students of the faculty of engineering and basic sciences, of the Universidad Francisco de Paula Santander, located in the city of Cúcuta, Colombia, during a 15-day time window, the analysis of the data and variables is carried out from the design of a mathematical model of logistic regression, where the dependent variable represents the feeling of emotional affect by the obligatory social isolation. The results indicated that the students feel emotionally affected in 88.56% generating implications in the learning of physics and in their academic performance, especially those who comply the profile: being female, single, not having received training in the use of digital platforms, without academic difficulties but who feel that their academic performance has been affected.
Fast frequency discrimination and phoneme recognition using a biomimetic membrane coupled to a neural network
Authors: Lee Woo Seok , Kim Hyunjae , Cleland Andrew N , Ahn Kang-Hun
Published: November 2020

In the human ear, the basilar membrane plays a central role in sound recognition. When excited by sound, this membrane responds with a frequency-dependent displacement pattern that is detected and identified by the auditory hair cells combined with the human neural system. Inspired by this structure, we designed and fabricated an artificial membrane that produces a spatial displacement pattern in response to an audible signal, which we used to train a convolutional neural network. When trained with single frequency tones, this system can unambiguously distinguish tones closely spaced in frequency. When instead trained to recognize spoken vowels, this system outperforms existing methods for phoneme recognition, including the discrete Fourier transform, zoom FFT and chirp z-transform, especially when tested in short time windows. This sound recognition scheme therefore promises significant benefits in fast and accurate sound identification compared to existing methods.
Decadal-scale hotspot methane ebullition within lakes following abrupt permafrost thaw
Authors: Walter Anthony K M , Lindgren P , Hanke P , Engram M , Anthony P , Daanen R P , Bondurant A , Liljedahl A K , Lenz J , Grosse G , Jones B M , Brosius L , James S R , Minsley B J , Pastick N J , Munk J , Chanton J P , Miller C E , Meyer F J
Published: November 2020

Thermokarst lakes accelerate deep permafrost thaw and the mobilization of previously frozen soil organic carbon. This leads to microbial decomposition and large releases of carbon dioxide (CO2) and methane (CH4) that enhance climate warming. However, the time scale of permafrost-carbon emissions following thaw is not well known but is important for understanding how abrupt permafrost thaw impacts climate feedback. We combined field measurements and radiocarbon dating of CH4 ebullition with (a) an assessment of lake area changes delineated from high-resolution (1–2.5 m) optical imagery and (b) geophysical measurements of thaw bulbs (taliks) to determine the spatiotemporal dynamics of hotspot-seep CH4 ebullition in interior Alaska thermokarst lakes. Hotspot seeps are characterized as point-sources of high ebullition that release 14C-depleted CH4 from deep (up to tens of meters) within lake thaw bulbs year-round. Thermokarst lakes, initiated by a variety of factors, doubled in number and increased 37.5% in area from 1949 to 2009 as climate warmed. Approximately 80% of contemporary CH4 hotspot seeps were associated with this recent thermokarst activity, occurring where 60 years of abrupt thaw took place as a result of new and expanded lake areas. Hotspot occurrence diminished with distance from thermokarst lake margins. We attribute older 14C ages of CH4 released from hotspot seeps in older, expanding thermokarst lakes (14CCH4 20 079 ± 1227 years BP, mean ± standard error (s.e.m.) years) to deeper taliks (thaw bulbs) compared to younger 14CCH4 in new lakes (14CCH4 8526 ± 741 years BP) with shallower taliks. We find that smaller, non-hotspot ebullition seeps have younger 14C ages (expanding lakes 7473 ± 1762 years; new lakes 4742 ± 803 years) and that their emissions span a larger historic range. These observations provide a first-order constraint on the magnitude and decadal-scale duration of CH4-hotspot seep emissions following formation of thermokarst lakes as climate warms.
Nutrient supply affects the yield stability of major European crops—a 50 year study
Authors: Ahrends Hella Ellen , Siebert Stefan , Rezaei Ehsan Eyshi , Seidel Sabine Julia , Hüging Hubert , Ewert Frank , Döring Thomas , Rueda-Ayala Victor , Eugster Werner , Gaiser Thomas
Published: November 2020

Yield stability is important for food security and a sustainable crop production, especially under changing climatic conditions. It is well known that the variability of yields is linked to changes in meteorological conditions. However, little is known about the long-term effects of agronomic management strategies, such as the supply of important nutrients. We analysed the stability of four major European crops grown between 1955 and 2008 at a long-term fertilization experiment located in Germany. Six fertilizer treatments ranged from no fertilization over the omission of individual macronutrients to complete mineral fertilization with all major macronutrients (nitrogen, phosphorus, potassium and calcium). Yield stability was estimated for each crop × treatment combination using the relative yield deviation in each year from the corresponding (nonlinear) trend value (relative yield anomalies (RYA)). Stability was lowest for potato, followed by sugar beet and winter wheat and highest for winter rye. Stability was highest when soils had received all nutrients with the standard deviation of RYA being two to three times lower than for unfertilized plots. The omission of nitrogen and potassium was associated with a decrease in yield stability and a decrease in the number of simultaneous positive and negative yield anomalies among treatments. Especially in root crops nutrient supply strongly influenced both annual yield anomalies and changes in anomalies over time. During the second half of the observation period yield stability decreased for sugar beet and increased for winter wheat. Potato yields were more stable during the second period, but only under complete nutrient supply. The critical role of potassium supply for yield stability suggests potential links to changes in the water balance during the last decades. Results demonstrate the need to explicitly consider the response of crops to long-term nutrient supply for understanding and predicting changes in yield stability.
Resetting dynamics in a confining potential
Authors: Singh R K , Metzler R , Sandev T
Published: November 2020

We study Brownian motion in a confining potential under a constant-rate resetting to a reset position x
0. The relaxation of this system to the steady-state exhibits a dynamic phase transition, and is achieved in a light cone region which grows linearly with time. When an absorbing boundary is introduced, effecting a symmetry breaking of the system, we find that resetting aids the barrier escape only when the particle starts on the same side as the barrier with respect to the origin. We find that the optimal resetting rate exhibits a continuous phase transition with critical exponent of unity. Exact expressions are derived for the mean escape time, the second moment, and the coefficient of variation (CV).
A random matrix perspective of cultural structure: groups or redundancies?
Authors: Băbeanu Alexandru-Ionuţ
Published: November 2020

Recent studies have highlighted interesting properties of empirical cultural states—collections of cultural trait sequences of real individuals. Matrices of similarity between individuals may be constructed from these states, allowing for more insights to be gained using random matrix techniques, approach first exploited in this study. We propose a null model that enforces, on average, the empirical occurrence frequency of each possible trait. With respect to this null model, the empirical matrices show deviating eigenvalues, which may be signatures of subtle cultural groups. However, they can conceivably also be artifacts of arbitrary redundancies between cultural variables. We study this possibility in a highly simplified setting, allowing for a side-by-side mathematical comparison of the two scenarios (groups and redundancies). The scenarios are shown to be completely indistinguishable in terms of deviating eigenvalues, confirming that the latter can in general be signatures of either redundancies or groups. The scenarios can be distinguished after evaluating the eigenvector uniformities and the associated deviations from null model expectations. This provides a uniformity-based validation criterion, which is reliable when searching for groups that are internally uniform, but fails when these exhibit significant internal non-uniformity. For empirical data, all the relevant eigenvector uniformities are compatible with the null model, indicating the absence of any internally uniform groups. Although there are various indications that some of the deviating eigenvalues could correspond to internally non-uniform groups, a generic procedure for distinguishing such groups from redundancy artifacts requires further research.
Choice of Si doping type for optimizing the performances of a SiOx-based tunneling electron source fabricated on SiOx/Si substrate
Authors: Yang Wei , Kong Siqi , Zhan Fangyuan , Li Zhiwei , Wang Yuwei , Wei Xianlong
Published: November 2020

A new type on-chip electron source based on electroformed SiOx is recently reported to show dense and efficient electron emission under low working voltage. Here we study the effect of the Si doping type of SiOx/Si substrate on the performances of the SiOx-based electron source fabricated on it. The electron source is composed of an array of parallelly integrated micro-emitters. Each micro-emitter is composed of a square nanogap with a width about 100 nm which is spaced by two concentric graphene films on the SiOx substrate. The inner graphene film contact with bottom Si electrode through a via hole opening to the bottom Si layer and the outer graphene film contact with the common metal electrode. Effective emission current and efficiency of the electron source are found to be significantly influenced by both the polarity of the driven voltage applied between the metal electrode and bottom Si layer and the polarity of the Schottky barrier at graphene-Si contact. The performances of electron sources can be optimized by choosing n-type doping of SiOx/Si substrate to make the positive influence of the two aspects achieved at the same time. An emission current up to 100 μA and emission density of 250 mA cm−2 are achieved for an optimized device with 64 micro-emitters at bias voltage of 32.8 V.
Rotigotine patch prescription in inpatients with Parkinson’s disease: evaluating prescription accuracy, delirium and end-of-life use
Authors: Ibrahim Hussein , Woodward Zoe , Pooley Jennifer , Richfield Edward William
Published: November 2020

Background

Rotigotine patch, a trans-dermal dopamine agonist, is used acutely to replace oral dopaminergic medications for inpatients with Parkinson’s disease where enteral routes are no longer available, and is also an option in end-of-life care where patients can no longer swallow. Concerns regarding acute use of Rotigotine include difficulty achieving dopaminergic equivalence, promotion of delirium/hallucinations and promotion of terminal agitation.

Objective

our objectives were to establish: (i) accuracy of Rotigotine prescribing, (ii) rates of delirium/hallucinations and (iii) rates of terminal agitation.

Method

we retrospectively evaluated the use of Rotigotine in an inpatient population at a UK teaching hospital. Prescriptions between January 2018 and July 2019 were identified and inpatient records were analysed. OPTIMAL Calculator 2 was used as a gold standard for assessing conversion of oral dopaminergic medication to Rotigotine.

Results

a total of 84 inpatients were included. 25 (30%) patients were prescribed the recommended dose of Rotigotine; 31 (37%) higher and 28 (33%) lower than recommended. A total of 15 of 41 (37%) patients with dementia and 22 of 49 (45%) patients with delirium before initiation of Rotigotine inappropriately received the higher dose; 20 (24%) patients developed new/worsening delirium and 8 (10%) patients developed new/worsening hallucinations; and 59 (70%) patients were dead at time of evaluation, of these 40 (68%) died in hospital, 10 (25%) of whom experienced terminal agitation.

Conclusions

acute conversion of oral dopaminergic medication to trans-dermal Rotigotine patch remains problematic despite the availability of validated tools. Inappropriate dosing may precipitate or worsen delirium/hallucinations. Use at end-of-life requires further evaluation.
Uterine decidual niche modulates the progressive dedifferentiation of spiral artery vascular smooth muscle cells during human pregnancy†
Authors: Ma Yeling , Yu Xin , Zhang Lanmei , Liu Juan , Shao Xuan , Li Yu-xia , Wang Yan-Ling
Published: November 2020

Uterine spiral artery (SPA) remodeling is a crucial event during pregnancy to provide enough blood supply to maternal–fetal interface and meet the demands of the growing fetus. Along this process, the dynamic change and the fate of spiral artery vascular smooth muscle cells (SPA–VSMCs) have long been debatable. In the present study, we analyzed the cell features of SPA–VSMCs at different stages of vascular remodeling in human early pregnancy, and we demonstrated the progressively morphological change of SPA–VSMCs at un-remodeled (Un-Rem), remodeling, and fully remodeled (Fully-Rem) stages, indicating the extravillous trophoblast (EVT)-independent and EVT-dependent phases of SPA–VSMC dedifferentiation. In vitro experiments in VSMC cell line revealed the efficient roles of decidual stromal cells, decidual natural killer cells (dNK), decidual macrophages, and EVTs in inducing VSMCs dedifferentiation. Importantly, the potential transformation of VSMC toward CD56+ dNKs was displayed by immunofluorescence-DNA in-situ hybridization-proximity ligation and chromatin immunoprecipitation assays for H3K4dime modification in the myosin heavy chain 11 (MYH11) promoter region. The findings clearly illustrate a cascade regulation of the progressive dedifferentiation of SPA–VSMCs by multiple cell types in uterine decidual niche and provide new evidences to reveal the destination of SPA–VSMCs during vascular remodeling.
Temporal Dynamics of Functional Brain States Underlie Cognitive Performance
Authors: Gu Hong , Schulz Kurt P , Fan Jin , Yang Yihong
Published: November 2020

The functional organization of the human brain adapts dynamically in response to a rapidly changing environment. However, the relation of these rapid changes in functional organization to cognitive functioning is not well understood. This study used a graph-based time-frame modularity analysis approach to identify temporally recurrent functional configuration patterns in neural responses to an n-back working memory task during fMRI. Working memory load was manipulated to investigate the functional relevance of the identified brain states. Four distinct brain states were defined by the predominant patterns of activation in the task-positive, default-mode, sensorimotor, and visual networks. Associated with escalating working memory load, the occurrence of the task-positive state and the probability of transitioning into this state increased. In contrast, the occurrence of the default-mode and sensorimotor states and the probability of these 2 states transitioning away from the task-positive state decreased. The task-positive state occurrence rate and the probability of transitioning from the default-mode state back to the task-positive state explained a significant and unique portion of the variance in task performance. The results demonstrate that dynamic brain activities support successful cognitive functioning and may have heuristic value for understanding abnormal cognitive functioning associated with multiple neuropsychiatric disorders.
Impact of intestinal ultrasound with a portable system in the management of Crohn’s disease
Authors: Gonen Can , Surmelioglu Ali , Kochan Koray , Ozer Serhat , Aslan Ekrem , Tilki Metin
Published: November 2020

Background

Intestinal ultrasound (IUS) is a valid cross-sectional imaging technique for the evaluation of Crohn’s disease (CD). With advancements in technology, portable ultrasound systems are becoming widely available, and the inevitable change to their use by non-radiologist clinicians would be a valuable contribution to improving patient care. This study aimed to investigate the diagnostic yield of IUS examination performed by a gastroenterologist with a portable system as an adjunct imaging modality in the routine care of CD patients.

Methods

A total of 117 CD patients were assessed by IUS imaging. Pre- and post-IUS clinical-management decisions were recorded. The primary outcome was to evaluate the change in the patients’ clinical-management decision following the IUS examination. The diagnostic accuracy was compared against the reference decision reached via a multidisiplinary meeting after the evaluation of all patient-related data. The endoscopic disease activity was determined using the simple endoscopic score for Crohn's disease (SES-CD).

Results

The initial clinical-management decision was changed in 47 patients (40.2%) after the IUS examination (P = 0.001). The accuracy of patient-management decisions improved from 63.2% to 90.6% in comparison to reference decisions (P < 0.001). After IUS examination, a further 13 cases (11.1%) were identified for urgent surgical/interventional procedures. The accuracy of colonoscopic (SES-CD ≥3) assessment was shown to be comparable to that of IUS (94% vs 91%). The sensitivity for disease presence was 95% with colonoscopy and 94% with the IUS assessment.

Conclusion

IUS examination with the use of a portable ultrasonography system significantly improves clinical-management decisions. With further supporting data, this practice would possibly become a requirement for CD management.
“She’s Dying and I Can’t Say We’re Married?”: End-of-Life Care for LGBT Older Adults
Authors: Candrian Carey , Cloyes Kristin G
Published: November 2020

Lesbian, gay, bisexual, and transgender (LGBT) older adults are at particular risk for receiving inequitable end-of-life care. Their health care wishes may be ignored or disregarded, their families of choice are less likely to be included in their decision making, and they may experience increased isolation, bullying, mistreatment, or abuse, which ultimately contribute to receipt of poor-quality health care. This is particularly important during sensitive transitions along the care continuum to end-of-life settings; 43% of respondents of a 2018 survey of 865 hospice professionals reported having directly observed discriminatory behavior toward LGBT patients. Lack of visibility and accountability perpetuates vulnerabilities and the potential for discriminatory treatment. Unfortunately, while other areas of health care have prioritized and normalized collecting sexual orientation and gender identity (SOGI) data, hospices do not routinely assess patients’ SOGI in the context of end-of-life wishes and decisions. Drawing insight from a sample of 31 in-depth interviews with older LGBT adults, this paper focuses on one participant’s story—Esther’s. We chose her story to illustrate how care can be compromised at the end of life if an open discussion with patients about what and who matters most to them at the end of life, is avoided.
War across the life course: examining the impact of exposure to conflict on a comprehensive inventory of health measures in an aging Vietnamese population
Authors: Zimmer Zachary , Fraser Kathryn , Korinek Kim , Akbulut-Yuksel Mevlude , Young Yvette Marie , Toan Tran Khanh
Published: November 2020

Background

The majority of evidence indicates that exposure to war and other traumatic events continue to have negative impacts on health across the life course. However, existing research on health effects of war exposure primarily concentrates on short-term impacts among veterans in high-income countries sent elsewhere to battle. Yet, most wars situate in lower- and middle-income countries, where many are now or will soon be entering old age. Consequently, the current burden of exposure to war has ignored an important global population.

Methods

The Vietnam Health and Aging Study (VHAS) is a longitudinal study designed to examine historical exposure to highly stressful events during the American War. Two modes of data collection, involving a sample of 2447 individuals aged 60+ years in northern Vietnam, took place between May and August 2018. Using this first wave of data, we generate indexed measures of war exposure and analyze their associations with a set of 12 health outcomes, accounting for confounding variables.

Results

Results indicate that greater exposure to three types of war exposure (death and injury, stressful living conditions, and fearing death and/or injury) in earlier life is associated with worse health in later-life across a large number of health outcomes, such as number of diagnosed health conditions, mental distress, somatic symptoms, physical functioning, post-traumatic stress symptoms and chronic pain.

Conclusions

Findings support a life course theory of health and point to long-term effects of war on health that require detailed attention.