bluuebunny/crossref_metadata_2025_split huggingface dataset:
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

AbstractThis 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

Abstract
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

Abstract
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

AbstractIn 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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract
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

Abstract

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

Abstract
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.