173 research outputs found
A Mode-Sum Prescription for Vacuum Polarization in Even Dimensions
We present a mode-sum regularization prescription for computing the vacuum
polarization of a scalar field in static spherically-symmetric black hole
spacetimes in even dimensions. This is the first general and systematic
approach to regularized vacuum polarization in higher even dimensions, building
upon a previous scheme we developed for odd dimensions. Things are more
complicated here since the even-dimensional propagator possesses logarithmic
singularities which must be regularized. However, in spite of this
complication, the regularization parameters can be computed in closed form in
arbitrary even dimensions and for arbitrary metric function . As an
explicit example of our method, we show plots for vacuum polarization of a
massless scalar field in the Schwarzschild-Tangherlini spacetime for even
. However, the method presented applies straightforwardly to
massive fields or to nonvacuum spacetimes.Comment: arXiv admin note: text overlap with arXiv:1609.0816
Gesture Decoding Using ECoG Signals from Human Sensorimotor Cortex: A Pilot Study
Electrocorticography (ECoG) has been demonstrated as a promising neural signal source for developing brain-machine interfaces (BMIs). However, many concerns about the disadvantages brought by large craniotomy for implanting the ECoG grid limit the clinical translation of ECoG-based BMIs. In this study, we collected clinical ECoG signals from the sensorimotor cortex of three epileptic participants when they performed hand gestures. The ECoG power spectrum in hybrid frequency bands was extracted to build a synchronous real-time BMI system. High decoding accuracy of the three gestures was achieved in both offline analysis (85.7%, 84.5%, and 69.7%) and online tests (80% and 82%, tested on two participants only). We found that the decoding performance was maintained even with a subset of channels selected by a greedy algorithm. More importantly, these selected channels were mostly distributed along the central sulcus and clustered in the area of 3 interelectrode squares. Our findings of the reduced and clustered distribution of ECoG channels further supported the feasibility of clinically implementing the ECoG-based BMI system for the control of hand gestures
Antibiotics in the offshore waters of the Bohai Sea and the Yellow Sea in China: Occurrence, distribution and ecological risks
The ocean is an important sink of land-based pollutants. Previous studies showed that serious antibiotic pollution occurred in the coastal waters, but limited studies focused on their presence in offshore waters. In this study, eleven antibiotics in three different categories were investigated in offshore waters of the Bohai Sea and the Yellow Sea in China. The results indicated that three antibiotics dehydration erythromycin, sulfamethoxazole and trimethoprim occurred throughout the offshore waters at concentrations of 0.10-16.6 ng L-1 and they decreased exponentially from the rivers to the coastal and offshore waters. The other antibiotics all presented very low detection rates (<10%) and concentrations (<0.51 ng L-1). Although the concentrations were very low, risk assessment based on the calculated risk quotients (RQs) showed that sulfamethoxazole, dehydration erythromycin and clarithromycin at most of sampling sites posed medium or low ecological risks (0.01 < RQ < 1) to some sensitive aquatic organisms, including Synechococcus leopoliensis and Pseudokirchneriella subcapitata. (C) 2012 Elsevier Ltd. All rights reserved.The ocean is an important sink of land-based pollutants. Previous studies showed that serious antibiotic pollution occurred in the coastal waters, but limited studies focused on their presence in offshore waters. In this study, eleven antibiotics in three different categories were investigated in offshore waters of the Bohai Sea and the Yellow Sea in China. The results indicated that three antibiotics dehydration erythromycin, sulfamethoxazole and trimethoprim occurred throughout the offshore waters at concentrations of 0.10-16.6 ng L-1 and they decreased exponentially from the rivers to the coastal and offshore waters. The other antibiotics all presented very low detection rates (<10%) and concentrations (<0.51 ng L-1). Although the concentrations were very low, risk assessment based on the calculated risk quotients (RQs) showed that sulfamethoxazole, dehydration erythromycin and clarithromycin at most of sampling sites posed medium or low ecological risks (0.01 < RQ < 1) to some sensitive aquatic organisms, including Synechococcus leopoliensis and Pseudokirchneriella subcapitata. (C) 2012 Elsevier Ltd. All rights reserved
Milestones in Autonomous Driving and Intelligent Vehicles Part II: Perception and Planning
Growing interest in autonomous driving (AD) and intelligent vehicles (IVs) is
fueled by their promise for enhanced safety, efficiency, and economic benefits.
While previous surveys have captured progress in this field, a comprehensive
and forward-looking summary is needed. Our work fills this gap through three
distinct articles. The first part, a "Survey of Surveys" (SoS), outlines the
history, surveys, ethics, and future directions of AD and IV technologies. The
second part, "Milestones in Autonomous Driving and Intelligent Vehicles Part I:
Control, Computing System Design, Communication, HD Map, Testing, and Human
Behaviors" delves into the development of control, computing system,
communication, HD map, testing, and human behaviors in IVs. This part, the
third part, reviews perception and planning in the context of IVs. Aiming to
provide a comprehensive overview of the latest advancements in AD and IVs, this
work caters to both newcomers and seasoned researchers. By integrating the SoS
and Part I, we offer unique insights and strive to serve as a bridge between
past achievements and future possibilities in this dynamic field.Comment: 17pages, 6figures. IEEE Transactions on Systems, Man, and
Cybernetics: System
Evidence of strong and mode-selective electron–phonon coupling in the topological superconductor candidate 2M-WS 2
The interaction between lattice vibrations and electrons plays a key role in various aspects of condensed matter physics — including electron hydrodynamics, strange metal behavior, and high-temperature superconductivity. In this study, we present systematic investigations using Raman scattering and angle-resolved photoemission spectroscopy (ARPES) to examine the phononic and electronic subsystems of the topological superconductor candidate 2M-WS2. Raman scattering exhibits an anomalous nonmonotonic temperature dependence of phonon linewidths, indicative of strong phonon–electron scattering over phonon–phonon scattering. The ARPES results demonstrate pronounced dispersion anomalies (kinks) at multiple binding energies within both bulk and topological surface states, indicating a robust and mode-selective coupling between the electronic states and various phonon modes. These experimental findings align with previous calculations of the Eliashberg function, providing a deeper understanding of the highest superconducting transition temperature observed in 2M-WS2 (8.8 K) among all transition metal dichalcogenides as induced by electron–phonon coupling. Furthermore, our results may offer valuable insights into other properties of 2M-WS2 and guide the search for high-temperature topological superconductors
Gene therapy: an emerging therapy for hair cells regeneration in the cochlea
Sensorineural hearing loss is typically caused by damage to the cochlear hair cells (HCs) due to external stimuli or because of one’s genetic factors and the inability to convert sound mechanical energy into nerve impulses. Adult mammalian cochlear HCs cannot regenerate spontaneously; therefore, this type of deafness is usually considered irreversible. Studies on the developmental mechanisms of HC differentiation have revealed that nonsensory cells in the cochlea acquire the ability to differentiate into HCs after the overexpression of specific genes, such as Atoh1, which makes HC regeneration possible. Gene therapy, through in vitro selection and editing of target genes, transforms exogenous gene fragments into target cells and alters the expression of genes in target cells to activate the corresponding differentiation developmental program in target cells. This review summarizes the genes that have been associated with the growth and development of cochlear HCs in recent years and provides an overview of gene therapy approaches in the field of HC regeneration. It concludes with a discussion of the limitations of the current therapeutic approaches to facilitate the early implementation of this therapy in a clinical setting
Fenofibrate suppresses corneal neovascularization by regulating lipid metabolism through PPARα signaling pathway
Purpose: The purpose of this study was to explore the potential underlying mechanism of anti-vascular effects of peroxisome proliferator–activated receptor α (PPARα) agonist fenofibrate against corneal neovascularization (CNV) through the changes of lipid metabolism during CNV.Methods: A suture-induced CNV model was established and the clinical indications were evaluated from day 1 to day 7. Treatments of vehicle and fenofibrate were performed for 5 days after suture and the CNV areas were compared among the groups. The eyeballs were collected for histological analysis, malondialdehyde (MDA) measurement, terminal deoxynucleotidyl transferase 2′-deoxyuridine 5′-triphosphate nick end labeling (TUNEL) staining, western blot, quantitative real-time PCR (qRT-PCR) assays and immunohistochemical (IHC) staining to elucidate pathological changes and the underlying mechanism.Results: Lipi-Green staining and MDA measurement showed that lipid deposition and peroxidation were increased in the CNV cornea while the expression of long-chain acyl-coenzyme A synthetase 1 (ACSL1), carnitine palmitoyltransterase 1A(CPT1A) and medium-chain acyl-coenzyme A dehydrogenase (ACADM), which are key enzymes of fatty acid β-oxidation (FAO) and targeted genes of peroxisome proliferator-activated receptor alpha (PPARα) pathway, were decreased in CNV cornea. Fenofibrate suppressed lipid accumulation and peroxidation damage in the CNV cornea. Fenofibrate upregulated the expression levels of PPARα, ACSL1, CPT1A, and ACADM compared with vehicle group. IHC staining indicated that fenofibrate also decreased the expression of VEGFa, VEGFc, TNFα, IL1β and CD68.Conclusion: Disorder of lipid metabolism may be involved in the formation of suture-induced CNV and fenofibrate played anti-neovascularization and anti-inflammatory roles on cornea by regulating the key enzymes of lipid metabolism and ameliorating lipid peroxidation damage of cornea through PPARα signaling pathway
Analysis of epidemiological characteristics of risk factors for cardiovascular diseases and malignant tumors based on the Shanghai community elderly cohort
Objective·To analyze the epidemiological characteristics of risk factors for cardiovascular diseases and malignant tumors based on the Shanghai community elderly cohort.Methods·The study subjects were selected from the Shanghai community elderly cohort established from February to August 2019, with a total of 17 948 people. The study subjects were divided into 4 groups according to self-reported presence or absence of tumors and/or cardiovascular diseases during the baseline survey: tumor-free and non-cardiovascular disease group, single cardiovascular disease group, single tumor group and tumor cardiovascular disease co-occurrence group. The differences among the four groups of subjects were collected and compared in terms of demographic characteristics and physiological indicators, daily living habits (smoking, drinking tea, drinking coffee, drinking carbonated drink, drinking alcohol, sedentary time, physical activity level and sleep quality), past medical history, psychological status (depression and anxiety) and dietary compliance.Results·Among the study subjects, 60.1% of tumor patients were complicated with cardiovascular diseases. The differences among the four groups of subjects in age, gender, educational level, pre-retirement occupation, waist circumference, hip circumference and body mass index were statistically significant (all P<0.05). Compared with the tumor-free and non-cardiovascular disease group, the single cardiovascular disease group, single tumor group and tumor cardiovascular disease co-occurrence group all exhibited lower proportions of smoking and high physical activity levels (all P<0.05), and higher proportion of sedentary time exceeding 4 h/d and poor sleep quality (all P<0.05); the proportion of subjects with past medical histories including hyperlipidemia, peripheral vascular disease, endocrine system disease, respiratory system disease, urinary system disease and digestive system disease of the single cardiovascular disease group and the tumor cardiovascular disease co-occurrence group was higher (all P<0.05), and the proportion of subjects with depression and anxiety was also higher (all P<0.05). Furthermore, compared with the tumor-free and non-cardiovascular disease group, the single cardiovascular disease group had lower compliance rates of poultry, fish, fruit and liquid milk (all P<0.05). Among the four groups, only the compliance rate of vegetable intake exceeded 50%, while the compliance rates of poultry, fish, fruit, liquid milk and tubers were all below 20%.Conclusion·In the elderly population of Shanghai communities, over half of malignant tumor patients are concomitant with cardiovascular diseases. Unhealthy daily habits are prevalent among those with cardiovascular diseases, tumors and tumor-cardiovascular disease co-occurrence. The intake of many foods in the elderly of the community do not reach the levels recommended by Chinese Dietary Guidelines
Milestones in autonomous driving and intelligent vehicles: survey of surveys
Interest in autonomous driving (AD) and intelligent vehicles (IVs) is growing at a rapid pace due to the convenience, safety, and economic benefits. Although a number of surveys have reviewed research achievements in this field, they are still limited in specific tasks, lack of systematic summary and research directions in the future. Here we propose a Survey of Surveys (SoS) for total technologies of AD and IVs that reviews the history, summarizes the milestones, and provides the perspectives, ethics, and future research directions. To our knowledge, this article is the first SoS with milestones in AD and IVs, which constitutes our complete research work together with two other technical surveys. We anticipate that this article will bring novel and diverse insights to researchers and abecedarians, and serve as a bridge between past and future
- …