Conditionals for representing implicational and causal knowledge

This thesis proposes a model-theoretic approach to address two foundational issues: the semantic conception of indicative conditionals, and that of causation. For many years both issues have remained a tangled series of open problems that attracted great efforts and heated debates among logicians and analytic philosophers, and it is no surprise that these open problems are very fundamental challenges for Artificial Intelligence. The solution proposed in this thesis includes two formal theories introduced in separate chapters. The first theory presents a logic that has a type of conditional for which the exact truth condition is defined, and we argue that using such conditionals enables the appropriate representation of indicative conditionals, or, more assertively, they are indicative conditionals. The second theory is an extension of the first one, where another type of conditional is defined to capture a unified notion of both general causation and specific actual causation. Both theories provide the semantic constructions that realise the desirable properties for representing and reasoning with implicational and causal knowledge without the traditional dilemma of sacrificing some other desirable properties for a formal logic. The Tarskian notion of entailment is preserved in the model theory. Some of these properties are expressed as theorems with proofs provided; other properties are shown by using the semantics to model a series of scenarios in the benchmark examples where we analyse how the difficulties for traditional approaches are resolved in this approach. The logical tools and fundamental claims resulting from this pair of semantic theories may bring a fresh viewpoint or even a general solution to the open problems mentioned above, and contribute to laying a better foundation for the formalisation of commonsense reasoning

Laser Beam Propagation through Oceanic Turbulence

Using a recently proposed model for the refractive index fluctuations in oceanic turbulence, optical beam propagation through seawater is explored. The model provides an accurate depiction of the ocean through the inclusion of both temperature and salinity fluctuations to the refractive index. Several important statistical characteristics are explored including spatial coherence radius, angle-of-arrival fluctuations, and beam wander. Theoretical values of these parameters are found based on weak fluctuation theory using the Rytov method. The results presented serve as a foundation for the study of optical beam propagation in oceanic turbulence, which may provide an important support for further researches in applications for underwater communicating, imaging, and sensing systems

Verification of the utility of molecular markers linked to the multiple-allele male-sterile gene Ms in the breeding of male-sterile lines of Chinese cabbage (Brassica rapa)

To verify the molecular markers linked to the genic multiple-allele male-sterile gene Ms, an F1 plant, which was generated by crossing the inbred line a20 and the male-sterile plant of the genic multipleallele male-sterile AB line, was backcrossed with an a20 plant to develop BC4 and BC5 populations. Sequence-characterized amplified region (SCAR) marker syau_scr01 and simple sequence repeat (SSR) marker syau_m13, which were linked to Ms, exhibited polymorphism between the 2 parents. The accuracies of these 2 markers in determining the plant genotype was 85 and 91.7%, respectively. The accuracy reached 100% when the 2 markers were used in combination. These results indicate that these 2 markers can be applied in the marker-assisted selection of the genic multiple-allele male-sterile line of Chinese cabbage.Keywords: Chinese cabbage, genic multiple-allele male sterility, marker-assisted selection, simple sequence repeat, sequence-characterized amplified regionAfrican Journal of Biotechnology Vol. 9(35), pp. 5623-5628, 30 August, 201

Polarized electron-beam acceleration driven by vortex laser pulses

We propose a new approach based on an all-optical set-up for generating relativistic polarized electron beams via vortex Laguerre-Gaussian (LG) laser-driven wakefield acceleration. Using a pre-polarized gas target, we find that the topology of the vortex wakefield resolves the depolarization issue of the injected electrons. In full three-dimensional particle-in-cell simulations, incorporating the spin dynamics via the Thomas-Bargmann Michel Telegdi equation, the LG laser preserves the electron spin polarization by more than 80% at high beam charge and flux. The method releases the limit on beam flux for polarized electron acceleration and promises more than an order of magnitude boost in peak flux, as compared to Gaussian beams. These results suggest a promising table-top method to produce energetic polarized electron beams.Comment: We replace some results and revise some description

A novel target state detection method for accurate cardiopulmonary signal extraction based on FMCW radar signals

Frequency-modulated continuous wave radar is capable of constant, real-time detection of human presence and monitoring of cardiopulmonary signals such as respiration and heartbeat. In highly cluttered environments or when the human body moves randomly, noise signals may be relatively large in some range bins, making it crucial to accurately select the range bin containing the target cardiopulmonary signal. In this paper, we propose a target range bin selection algorithm based on a mixed-modal information threshold. We introduce a confidence value in the frequency domain to determine the state of the human target and employ the range bin variance in the time domain to determine the range bin change status of the target. The proposed method accurately detects the state of the target and effectively selects the range bin containing the cardiopulmonary signal with a high signal-to-noise ratio. Experimental results demonstrate that the proposed method achieves better accuracy in cardiopulmonary signal rate estimation. Moreover, the proposed algorithm is lightweight in data processing and has good real-time performance

Simultaneous Determination of 49 Antibiotics Residues in Pork by a Modified QuEChERS Method Based on Silanized Melamine Sponge Coupled with Ultra-high Performance Liquid Chromatography-Tandem Mass Spectrometry

Two new types of elastic porous silanized melamine sponges (MeS) were prepared by silylation reaction using octadecyltrichlorosilane (OTS) and N-[3-(trimethoxysilyl)propyl]ethylenediamine (ATS), which were respectively designated as OTS@MeS and ATS@MeS. The silanized sponges were used to develop a modified quick, easy, check, effective, rugged, and safe (QuEChERS) method that can quickly and efficiently separate interfering matrices from the extract through spontaneous solution infiltration and physical extrusion. In this study, an analytical method using the modified QuEChERS procedure combined with ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) was established for the simultaneous determination of 49 antibiotic residues in pork. Samples were extracted with 10 mL of acetonitrile containing 0.1% acetic acid, and then salted out with 2.0 g of Na2SO4 and 0.5 g of NaCl. After centrifugation, a 1 mL aliquot of the supernatant was cleaned up with a mixture of OTS@MeS and ATS@MeS. The chromatographic separation was conducted on an Agilent ZORBAX Eclipse Plus C18 column with gradient elution using a mobile phase comprised of methanol and aqueous solution (methanol/water, 5:95, V/V) containing 0.1% formic acid and 5 mmol/L ammonium acetate. The qualitative and quantitative detection were performed by multiple-reaction monitoring (MRM) using an electrospray ionization source in the positive ion mode. The results showed that the correlation coefficients for all analytes were greater than 0.999. The matrix effects (ME) were in the range of −13.5%−10.9%. The limits of detection (LOQ) and quantitation (LOQ) were 0.1–10.0 and 0.3–33.3 μg/kg, respectively. The recoveries at three spiked levels ranged from 65.0% to 112.7%, with intra- and interday relative standard deviations (RSDs) of 0.3%–11.8% and 2.4%–18.4%, respectively. The developed method was simple, rapid, highly sensitive and accurate, and could be used for the efficient and rapid determination of the 49 antibiotics residues in pork

Plasmonic‐enhanced NIR‐II downconversion fluorescence beyond 1500 nm from core–shell–shell lanthanide nanoparticles

This paper reports on the light amplification of NaGdF4:Yb,Er,Ce@NaGdF4:Yb,Nd@NaGdF4 core–shell–shell downconversion nanoparticles (CSS‐DCNPs) in the near‐infrared second biological window (NIR‐II: 1000–1700 nm) by plasmonic nanostructures. Through a precisely controlled plasmonic metallic nanostructure, fluorescence from Yb3+ induced 1000 nm emission, Nd3+ induced 1060 nm emission, and Er3+ induced 1527 nm emission are enhanced 1.6‐fold, 1.7‐fold, and 2.2‐fold, respectively, under an 808 nm laser excitation for the CSS‐DCNPs coupled with a gold hole‐cap nanoarray (Au‐HCNA), while the Er3+ induced 1527 nm emission under a 980 nm laser excitation is enhanced up to 6‐fold. To gain insight into the enhancement mechanism, the plasmonic modulation of Er3+ induced NIR‐II emission at 1550 nm under 980 nm excitation is studied by FDTD simulation and lifetime measurements, showing the observed fluorescence enhancement can be attributed to a combination of enhanced excitation and an increased radiative decay rate

The 2023 wearable photoplethysmography roadmap

Photoplethysmography is a key sensing technology which is used in wearable devices such as smartwatches and fitness trackers. Currently, photoplethysmography sensors are used to monitor physiological parameters including heart rate and heart rhythm, and to track activities like sleep and exercise. Yet, wearable photoplethysmography has potential to provide much more information on health and wellbeing, which could inform clinical decision making. This Roadmap outlines directions for research and development to realise the full potential of wearable photoplethysmography. Experts discuss key topics within the areas of sensor design, signal processing, clinical applications, and research directions. Their perspectives provide valuable guidance to researchers developing wearable photoplethysmography technology

Real-time virtual reference service based on applicable artificial intelligence technologies: The début of the robot Xiaotu at Tsinghua University Library

The adoption of applicable artificial intelligence technologies to library real-time virtual reference services is an innovative experimentation in one of the key areas of library services. Based on the open source software Artificial Linguistic Internet Computer Entity (A.L.I.C.E.) and a combined application of several other relevant supporting technologies for facilitating the use of the current existing library resources, Tsinghua University Library has recently developed a real-time smart talking robot, named Xiaotu, for the enhancement of its various service functions, such as reference services, book searching, Baidu Baike searching, self-directed learning, etc. The operation of Xiaotu is programmed into Renren website (a social networking website), which adds significantly an innovative feature to the modus operandi of the real-time virtual reference service at Tsinghua University Library.</p