bluuebunny/crossref_metadata_2025_split huggingface dataset:
Generating infinitesimal transformations with second-order-infinitesimal accuracy for proving covariance of commutation relations under finite transformations
Authors: Belinfante Frederik J. 
Published: July 2002

As dynamical quantization of Einstein’s gravitational theory meets unsolved problems, it is worth considering the alternative method of quantization suggested by Fermi’s quantization of special-relativistic electrodynamics, which for that theory has been the starting point of most modern applications of quantum electrodynamics. This method avoids first-class constraints by an alteration of the Lagrangian. In physical formulas, this introduces unwanted terms, that are at the end equated weakly to zero by auxiliary conditions. By absence of first-class constraints, this theory could be quantized canonically, if it would not contain fermion fields. As shown by Dirac, in the presence of fermion fields the canonical commutation relations of the altered theory have to be replaced by modified commutation relations. The ultimate purpose of this and following papers is to prove the covariance of Dirac’s modified commutation relations, first under infinitesimal transformations, and thence under finite transformations. As usual, this requires the proof of existence of a conserved and invariant generator for the transformations admitted, here coordinate transformations and local Lorentz transformations of the tetrad field. For infinitesimal transformations, the conventional method of deriving from the Lagrangian density ℒ a generator T1 linear in the infinitesimal parameters that determine the transformations is used. However, for guaranteeing integrability of the procedure for generating transformations of the field variables, from infinitesimal transformations to finite transformations, it is necessary to show the existence of a more accurate generator T, no longer linear in the parameters, which will by eiTFe−iT−F generate the transformations δ̄F of the field variables F with second-order accuracy.
While it is left to a following paper to discuss the exact form of Dirac’s modified commutation relations and to prove the conservation and covariance of the generator T and to prove that the conventional first-order generator T1 will, this time by Dirac’s modified commutation relations, generate the first-order substantial variations δ̄1F of the field variables, in the present paper formulas are derived for expressing the second-order-infinitesimal terms in the transformation formulas by means of the first-order terms, and a method is derived for obtaining from T1 the more accurate generator T. Finally, it is verified that the transformations F(x)→F′(x′) =F(x)+δ̄F generated by the generators T do satisfy the transformation group property with second-order accuracy.
Chemical energy release and dynamics of transitional, reactive shear flows
Authors: Grinstein F. F. , Kailasanath K. 
Published: July 2002

Results are reported from numerical studies of a compressible, subsonic reactive mixing layer, on the the effects of chemical-reaction exothermicity on the shear-layer development, and the dependence of these effects on initial conditions. The model solves the unsteady, conservation equations for mass, momentum, energy, and species concentrations. The convective transport equations are solved using the flux-corrected transport (FCT) algorithm and appropriate inflow and outflow boundary conditions. A one-step, irreversible, Arrhenius chemical reaction rate, and realistic (species- and temperature-dependent) modeling of diffusive transport are coupled with the convective transport using time-step splitting. The system studied consists of nonpremixed coflowing streams, where both the fuel (faster stream, hydrogen) and the oxidizer (slower stream, oxygen) are diluted in nitrogen. To facilitate the analysis of the results the flow is organized by low-level, single-frequency velocity perturbation at the inflow. The simulations show that energy release has the effect of reducing the shear layer growth and the amount of chemical product formed−relative to the corresponding cases for which exothermicity is not accounted for, in qualitative agreement with results from previous investigations. The relative mixing-layer growth reduction becomes more pronounced for larger energy release and lower Re, and is significant in terms of both, Reynolds stress, ρu′v′, and the velocity-fluctuation correlation u′v′.
In spite of the relatively fast flows studied, for the regimes considered, the results on the initial mixing-layer growth are significantly sensitive to diffusive transport effects−more so in terms of Reynolds stress, than in terms of product formation. With larger energy release here associated to larger free-stream reactant molar fractions c0, the amount of chemical product in absolute terms is found to increase with energy release−but slower than c0, so that the product formation becomes effectively less efficient. The results of the present work highlight the difficulties involved in making general statements about the effects of exothermicity on the mixing-layer growth, indicating that a careful conceptualization of these properties in terms of initial conditions and other characteristic parameters of the reactive systems under study is required.
Values of the Legendre chi and Hurwitz zeta functions at rational arguments
Authors: Cvijović Djurdje , Klinowski Jacek 
Published: July 2002

We show that the Hurwitz zeta function,

ζ
(
ν
,
a
)

\zeta (\nu ,a)

, and the Legendre chi function,

χ
ν

(
z
)

\chi _\nu (z)

, defined by
\[

ζ
(
ν
,
a
)
=

∑

k
=
0

∞

1

(
k
+
a

)
ν

,

0
>
a
≤
1
,
Re

ν
>
1
,

\zeta (\nu ,a)=\sum _{k=0}^\infty \frac {1}{(k+a)^\nu },\quad 0>a\le 1,\operatorname {Re}\,\nu >1,

\]
and
\[

χ
ν

(
z
)
=

∑

k
=
0

∞

z

2
k
+
1

(
2
k
+
1

)
ν

,

|

z

|

≤
1
,
Re

ν
>
1
with
ν
=
2
,
3
,
4
,
…
,

\chi _\nu (z)=\sum _{k=0}^\infty \frac {z^{2k+1}}{(2k+1)^\nu },\quad |z|\le 1,\operatorname {Re}\,\nu >1 \text {with} \nu =2,3,4,\dotsc ,

\]
respectively, form a discrete Fourier transform pair. Many formulae involving the values of these functions at rational arguments, most of them unknown, are obtained as a corollary to this result. Among them is the further simplification of the summation formulae from our earlier work on closed form summation of some trigonometric series for rational arguments. Also, these transform relations make it likely that other results can be easily recovered and unified in a more general context.
Findings From Severe Maternal Morbidity Surveillance and Review in Maryland
Authors: Wolfson Carrie , Qian Jiage , Chin Pamela , Downey Cathy , Mattingly Katie Jo , Jones-Beatty Kimberly , Olaku Joanne , Qureshi Sadaf , Rhule Jane , Silldorff Danielle , Atlas Robert , Banfield Anne , Johnson Clark T. , Neale Donna , Sheffield Jeanne S. , Silverman David , McLaughlin Kacie , Koru Güneş , Creanga Andreea A. 
Published: November 2022

ImportanceIn the US, more than 50 000 women experience severe maternal morbidity (SMM) each year, and the SMM rate more than doubled during the past 25 years. In response, professional organizations called for birthing facilities to routinely identify and review SMM events and identify prevention opportunities.ObjectiveTo examine SMM levels, primary causes, and factors associated with the preventability of SMM using Maryland’s SMM surveillance and review program.Design, Setting, and ParticipantsThis cross-sectional study included pregnant and postpartum patients at 42 days or less after delivery who were hospitalized at 1 of 6 birthing hospitals in Maryland between August 1, 2020, and November 30, 2021. Hospital-based SMM surveillance was conducted through a detailed review of medical records.ExposuresHospitalization during pregnancy or within 42 days post partum.Main Outcomes and MeasuresThe main outcomes were admission to an intensive care unit, having at least 4 U of red blood cells transfused, and/or having COVID-19 infection requiring inpatient hospital care.ResultsA total of 192 SMM events were identified and reviewed. Patients with SMM had a mean [SD] age of 31 [6.49] years; 9 [4.7%] were Asian, 27 [14.1%] were Hispanic, 83 [43.2%] were non-Hispanic Black, and 68 [35.4%] were non-Hispanic White. Obstetric hemorrhage was the leading primary cause of SMM (83 [43.2%]), followed by COVID-19 infection (57 [29.7%]) and hypertensive disorders of pregnancy (17 [8.9%]). The SMM rate was highest among Hispanic patients (154.9 per 10 000 deliveries), primarily driven by COVID-19 infection. The rate of SMM among non-Hispanic Black patients was nearly 50% higher than for non-Hispanic White patients (119.9 vs 65.7 per 10 000 deliveries). The SMM outcome assessed could have been prevented in 61 events (31.8%). Clinician-level factors and interventions in the antepartum period were most frequently cited as potentially altering the SMM outcome. Practices that were performed well most often pertained to hospitals’ readiness and adequate response to managing pregnancy complications. Recommendations for care improvement focused mainly on timely recognition and rapid response to such.Conclusions and RelevanceThe findings of this cross-sectional study, which used hospital-based SMM surveillance and review beyond the mere exploration of administrative data, offers opportunities for identifying valuable quality improvement strategies to reduce SMM. Immediate strategies to reduce SMM in Maryland should target its most common causes and address factors associated with preventability identified at individual hospitals.
The effect of microlevel and macrolevel signaling on learning with 360° videos
Authors: Beege Maik , Nebel Steve , Schneider Sascha , Rey Günter Daniel 
Published: November 2022

AbstractThe application of 360° videos raised the attention of educators and researchers, as it appears to be an approachable option to mediate complete environments in educational settings. However, challenges emerge from the perspective of educational psychology. Learning irrelevant cognitive strains might be imposed because it is necessary to navigate through spherical material. However, these potential downsides could be compensated for using signaling techniques. In a two (macrolevel vs. no macrolevel signaling) × two (microlevel vs. no microlevel signaling) factorial between‐subjects design plus control group, 215 fifth‐and sixth‐grade students will watch a 360° video about visual and behavioral characteristics of animals. Learning outcomes, cognitive load, disorientation, and presence will be investigated. It is expected that macrolevel signaling will enhance learning and presence and reduce cognitive load and disorientation. Microlevel signaling will have comparable advantages, but these effects will be more pronounced when macrolevel signaling is implemented.
Command filter‐based adaptive neural network controller design for uncertain nonsmooth nonlinear systems with output constraint
Authors: Xu Qian , Zong Guangdeng , Chen Yunjun , Niu Ben , Shi Kaibo 
Published: November 2022

SummaryThis paper investigates the command filter‐based adaptive neural network tracking control problem for uncertain nonsmooth nonlinear systems. First, an integral barrier Lyapunov function is introduced to deal with the symmetric output constraint and make the output comply with prescribed restrictions. Second, by the Filippov's differential inclusion theory and approximation theorem, the considered nonsmooth nonlinear system is converted to an equivalent smooth nonlinear system. Third, the Levant's differentiator is used to deal with the “explosion of complexity” problem. An error compensation mechanism is established to attenuate the effect of the filtering error on control performance. Then, an adaptive neural network controller is set up by resorting to the backstepping technique. It is strictly mathematically proved that the tracking error can converge to an arbitrarily small neighborhood of the origin and all the signals in the closed‐loop system are semi‐globally uniformly ultimately bounded. Finally, a numerical example and an application example of the robotic manipulator system are provided to demonstrate the availability of the proposed control strategy.
Nanosonosensitizer‐Augmented Sono‐Immunotherapy for Glioblastoma by Non‐Invasive Opening of the Blood–Brain Barrier
Authors: Lin Danmin , Wang Zhen , Long Wei , Xu Mingze , Liu Aolu , Gao Yifei , Wen Zhu , Liu Chao , He Jiecheng , Cheng Yuxue , Jiang Siyuan , Chen Jiapeng , Liu Qingpeng , Zhang Lingkun , You Rong , Yin Liang , Guan Yanqing 
Published: November 2022

AbstractThe presence of blood–brain barrier (BBB) that limits effective penetration of therapeutics is the main reason for poor outcomes of glioblastoma (GBM) treatment. Ultrasound (US) combined with microbubbles (MBs) can precisely disrupt the tight junctions of brain endothelial cells, thus creating “acoustic pores” and non‐invasive opening the BBB. Here, chitosan oligosaccharide (COS) is conjugated with a sonosensitizer protoporphyrin IX (PpIX) and an immune‐enhancing adjuvant Poly(I:C) via electrostatic adsorption, and cross‐linked with a tumor‐targeting molecule hyaluronic acid (HA) affording nanosonosensitizers HA‐Poly(I:C)/COS‐PpIX (abbreviated as “HP/CP” NSs). HP/CP NSs can target and penetrate GBMs, and trigger reactive oxygen species production upon US, simultaneously causing mitochondrial dysfunction and DNA damage. Tumor‐associated antigens released by sonodynamic therapy‐induced immunogenic cell death and loaded Poly(I:C) form an in situ vaccine together to potentiate antitumor immune responses. In orthotopic GBM mice models, the HP/CP+US treatments prolong mice survival, enhance cytotoxic T‐lymphocytes infiltration, and activate peripheral immune circulation. Besides, HP/CP NSs possess favorable biosafety profiles. Collectively, this study sheds light on the application of HP/CP NSs for synergistic sono‐immunotherapy of GBMs after non‐invasive opening of the BBB.
Segregated and Non‐Settling Liquid Metal Elastomer via Jamming of Elastomeric Particles
Authors: Xue Xiaoting , Zhang Dongguang , Wu Yali , Xing Ruizhe , Li Hong , Yu Tingting , Bai Bowen , Tao Yebo , Dickey Michael D. , Yang Jiayi 
Published: November 2022

AbstractLiquid metal elastomer (LME)—that is, liquid metal particles dispersed in elastomer—is a soft material that has useful electric, dielectric, and thermal properties. Two issues with LME are sought to be addressed: 1) the dense liquid metal (LM) particles can settle before curing of the elastomer, and 2) the LM particles are separated by a thin layer of insulating elastomer and therefore require some “mechanical sintering” to break this layer to create conductive paths. These issues are addressed using an LME containing elastic particles (LMEP). Elastic polydimethylsiloxane particles (PPs) and LM particles jam to prevent particle settling. Meanwhile, the PPs reduce the loading necessary to create conductive paths, thus decreasing the density and cost relative to LME. Surprisingly, the particles percolate into conductive paths prior to curing the LMEP but not in LME. The dielectric constant, electrical conductivity, and thermal conductivity of LMEPs are investigated by changing the volume fraction of LM particles, polydimethylsiloxane pre‐polymer and PPs, and propose an LMEP with the optimal ratio. In addition, LMEP‐based sensors and circuits are demonstrated for wearable electronics.
Panoramic Mapping of Phonon Transport from Ultrafast Electron Diffraction and Scientific Machine Learning
Authors: Chen Zhantao , Shen Xiaozhe , Andrejevic Nina , Liu Tongtong , Luo Duan , Nguyen Thanh , Drucker Nathan C. , Kozina Michael E. , Song Qichen , Hua Chengyun , Chen Gang , Wang Xijie , Kong Jing , Li Mingda 
Published: November 2022

AbstractOne central challenge in understanding phonon thermal transport is a lack of experimental tools to investigate frequency‐resolved phonon transport. Although recent advances in computation lead to frequency‐resolved information, it is hindered by unknown defects in bulk regions and at interfaces. Here, a framework that can uncover microscopic phonon transport information in heterostructures is presented, integrating state‐of‐the‐art ultrafast electron diffraction (UED) with advanced scientific machine learning (SciML). Taking advantage of the dual temporal and reciprocal‐space resolution in UED, and the ability of SciML to solve inverse problems involving coupled Boltzmann transport equations, the frequency‐dependent interfacial transmittance and frequency‐dependent relaxation times of the heterostructure from the diffraction patterns are reliably recovered. The framework is applied to experimental Au/Si UED data, and a transport pattern beyond the diffuse mismatch model is revealed, which further enables a direct reconstruction of real‐space, real‐time, frequency‐resolved phonon dynamics across the interface. The work provides a new pathway to probe interfacial phonon transport mechanisms with unprecedented details.
Complex Living Materials Made by Light‐Based Printing of Genetically Programmed Bacteria
Authors: Binelli Marco R. , Kan Anton , Rozas Luis E. A. , Pisaturo Giovanni , Prakash Namita , Studart André R. 
Published: November 2022

AbstractLiving materials with embedded microorganisms can genetically encode attractive sensing, self‐repairing, and responsive functionalities for applications in medicine, robotics, and infrastructure. While the synthetic toolbox for genetically engineering bacteria continues to expand, technologies to shape bacteria‐laden living materials into complex 3D geometries are still rather limited. Here, it is shown that bacteria‐laden hydrogels can be shaped into living materials with unusual architectures and functionalities using readily available light‐based printing techniques. Bioluminescent and melanin‐producing bacteria are used to create complex materials with autonomous chemical‐sensing capabilities by harnessing the metabolic activity of wild‐type and engineered microorganisms. The shaping freedom offered by printing technologies and the rich biochemical diversity available in bacteria provides ample design space for the creation and exploration of complex living materials with programmable functionalities for a broad range of applications.
Electropneumatic Surfaces: Pairing Electrowetting and Air Pressure for Reversible Droplet Mobility Switching
Authors: Markodimitrakis Ioannis E. , Vourdas Nikolaos , Papathanasiou Athanasios G. 
Published: November 2022

AbstractDesigning surfaces with controllable wettability and exploring methodologies for manipulating liquid motion on solid surfaces is an important research challenge. The impact on various interdisciplinary applications, ranging from self‐cleaning technology to the handling of droplets on Lab‐on‐a‐Chip self‐diagnostic devices, is expected to be significant. In this work, it is studied how the combined action of electric fields and pneumatic actuation can be used to achieve wetting transitions from states where droplets stick to surfaces, to states where droplets slide easily with low friction. The manipulation of water droplets on air‐permeable porous surfaces using both electric fields (electrowetting) and air‐pressure is investigated. The control over droplet mobility is achieved by tuning the solid‐liquid adhesion upon voltage application, in order to pin the droplet; de‐pinning is achieved by air pressure application through surface pores. This way low energy consumption and efficient switching between extreme wetting states and droplet mobility are realized.
In Vivo Anchoring Bis‐Pyrene Probe for Molecular Imaging of Early Gastric Cancer by Endoscopic Techniques
Authors: Luo Qiang , Fan Chaoqiang , Ying Wang , Peng Xue , Hu Yiyang , Luan Zhaohui , Ye Shaosong , Gong Chunli , Huang Yu , Xiao Yufeng , Chen Yang , Xing Malcolm , Wang Lei , Yang Shiming 
Published: November 2022

AbstractWith the development of blue laser endoscopy (BLE) technique, it's often used to diagnose early gastric cancer (EGC) by the morphological changes of blood vessels through BLE. However, EGC is still not obvious to identify, resulting in a high rate of missed diagnosis. Molecular imaging can show the changes in early tumors at molecular level, which provides a possibility for diagnosing EGC. Therefore, developing a probe that visually monitors blood vessels of EGC under BLE is particularly necessary. Herein, a bis‐pyrene (BP) based nanoprobe (BP‐FFVLK‐(PEG)‐RGD, M1) is designed, which can target angiogenesis and self‐assemble into fibers in situ, resulting in stable and long‐term retention in tumor. Moreover, M1 probe can emit yellow‐green fluorescence for imaging under BLE. M1 probe is confirmed to steadily remain in tumor for up to 96 hours in mice transplanted subcutaneously. In addition, the M1 probe is able to target angiogenesis for molecular imaging of isolated human gastric cancer tissue under BLE. Finally, M1 probe i.v. injected into primary gastric cancer model rabbits successfully highlighted the tumor site under BLE, which is confirmed by pathological analysis. It's the first time to develop a probe for diagnosing EGC by visualizing angiogenesis under BLE, showing great clinical significance.
Multiplexed Complementary Signal Transmission for a Self‐Regulating Artificial Nervous System
Authors: Choi Young Jin , Roe Dong Gue , Choi Yoon Young , Kim Seongchan , Jo Sae Byeok , Lee Hwa Sung , Kim Do Hwan , Cho Jeong Ho 
Published: November 2022

AbstractNeuromorphic engineering has emerged as a promising research field that can enable efficient and sophisticated signal transmission by mimicking the biological nervous system. This paper presents an artificial nervous system capable of facile self‐regulation via multiplexed complementary signals. Based on the tunable nature of the Schottky barrier of a complementary signal integration circuit, a pair of complementary signals is successfully integrated to realize efficient signal transmission. As a proof of concept, a feedback‐based blood glucose level control system is constructed by incorporating a glucose/insulin sensor, a complementary signal integration circuit, an artificial synapse, and an artificial neuron circuit. Certain amounts of glucose and insulin in the initial state are detected by each sensor and reflected as positive and negative amplitudes of the multiplexed presynaptic pulses, respectively. Subsequently, the pulses are converted to postsynaptic current, which triggered the injection of glucose or insulin in a way that confined the glucose level to a desirable range. The proposed artificial nervous system demonstrates the notable potential of practical advances in complementary control engineering.
Revealing Photodegradation Pathways of Organic Solar Cells by Spectrally Resolved Accelerated Lifetime Analysis
Authors: Weitz Paul , Le Corre Vincent Marc , Du Xiaoyan , Forberich Karen , Deibel Carsten , Brabec Christoph J. , Heumüller Thomas 
Published: November 2022

AbstractA method for organic solar cell (OSC) stability testing is presented that aims to provide more unique insight into the causes of degradation patterns of OSCs. The method involves using monochromatic light at high irradiation doses to accelerate isolated degradation mechanisms while monitoring the device with a series of in‐situ steady‐state and transient electrical measurements. The experimental results are accompanied by drift‐diffusion simulations to localize degradation pathways. PM6:Y6‐based OSCs are tested, which are known to show a rather broad range of lifetimes as a function of device architecture, material batches, or degradation conditions. The experiments reveal a degradation mechanism that causes an increased trap‐state density inside the PM6:Y6 layer. The transient simulations suggest that these states are formed at or around the interface between the PM6:Y6 and the electron transport layer. Furthermore, the surprisingly dominant impact of the illuminating wavelength on the degradation pattern is evidenced. Lastly, the degradation rate of the devices scales linearly with light intensity, making high intensity and spectrally selective degradation the most promising way to accelerate stability testing for the faster development of stable OSCs.