Studies on Novel Anti-jamming Technique of Unmanned Aerial Vehicle Data Link

Based on the M-ary spread spectrum （M-ary-SS）, direct sequence spread spectrum （DS-SS）, and orthogonal frequency division multiplex （OFDM）, a novel anti-jamming scheme, named orthogonal code time division multi-subchannels spread spectrum modulation （OC-TDMSCSSM）, is proposed to enhance the anti-jamming ability of the unmanned aerial vehicle （UAV） data link. The anti-jamming system with its mathematical model is presented first, and then the signal formats of transmitter and receiver are derived. The receiver＇s bit error rate （BER） is demonstrated and anti-jamming performance analysis is carded out in an additive white Ganssian noise （AWGN） channel. Theoretical research and simulation results show the anti-jamming performance of the proposed scheme better than that of the hybrid direct sequence frequency hopping spread spectrum （DS/FH SS） system. The jamming margin of the OC-TDMSCSSM system is 5 dB higher than that of DS/FH SS system under the condition of Rician channel and full-band jamming, and 6 dB higher under the condition of Rician channel environment and partial-band jamming.

Combined algorithm of acquisition and anti-jamming based on SFT

A communication and navigation receiver is required to remove hostile jamming signals and synchronize receiving signals effectively especially for satellite communication and navigation whose resources are becoming more and more limited. This paper proposes a novel signal receiving method by combining the pro- cesses of anti-jamming and synchronization to reduce the overall computationa~ complexity at the expense of slightly affecting the detection probability, which is analyzed in detail by derivations. Furthermore, this paper introduces sparse Fourier transformation （SFT） into the proposed algorithm to replace fast Fourier transfor- mation （FFT） so as to further reduce the calculation time especially in large frequency offset environments.

Cognitive anti-jamming receiver under phase noise in high frequency bands

This paper investigates the jamming sensing performance of the simultaneous transmit and receive based cognitive anti-jamming(SCAJ) receiver impaired by phase noise in local oscillators(LO) over fading channels. Firstly, energy detection(ED)based on the jamming to noise ratio(JNR) of the high frequency bands SCAJ receiver with phase noise under different channels is analyzed. Then, the probabilities of jamming detection and false alarm in closed-form for the SCAJ receiver are derived. Finally,the modified Bayesian Cramer-Rao bound(BCRB) of jamming sensing for the SCAJ receiver is presented. Simulation results show that the performance degradation of the SCAJ system due to phase noise is more severe than that due to the channel fading in the circumstances where the signal bandwidth(BW) is kept a constant. Moreover, the signal BW has an effect on the phase noise in LO, and the jamming detection probability of the wideband SCAJ receiver with lower phase noise outperforms that of the narrowband receiver using the same center frequency. Furthermore,an accurate phase noise estimation and compensation scheme can improve the jamming detection capability of the SCAJ receiver in high frequency bands and approach to the upper bound.

Space-borne antenna adaptive anti-jamming method based on gradient-genetic algorithm

A novel space-borne antenna adaptive anti-jamming method based on the genetic algorithm （GA）, which is combined with gradient-like reproduction operators is presented, to search for the best weight for pattern synthesis in radio frequency （RF）. Combined, the GA＇s the capability of the whole searching is, but not limited by selection of the initial parameter, with the gradient algorithm＇s advantage of fast searching. The proposed method requires a smaller sized initial population and lower computational complexity. Therefore, it is flexible to implement this method in the real-time systems. By using the proposed algorithm, the designer can efficiently control both main-lobe shaping and side-lobe level. Simulation results based on the spot survey data show that the algorithm proposed is efficient and feasible.

Comparison of the Radar Receiver Anti-Jamming Circuits Performance

This paper researches on some key technologies of anti-jamming of an air-borne radar receiver, the automatic testing of AGC, IAGC and multi-filtering under one million noisy pulses by the computer simulation system. The system tests the width of the jamming pulse whose width is 100% bigger, 60% bigger and 100% smaller than the Radar signal’s respectively and show the SNR curve.

An Adaptive Anti-jamming and Interference Coding Scheme for Frequency Hop Spread-Spectrum Communication Systems

In this paper, we propose a new adaptive coding scheme for frequency-hop spread-spec-trum communication systems against jamming and interference. The scheme consists of an adaptive decoding algorithm, adaptive forward error-correction using incremental redundancy and adaptive transmission rate control, which ensure the systems with extremely high reliability and efficiency.

EFFICIENT DESIGN OF ANTI-JAMMING RATELESS CODING IN COGNITIVE OFDM

Efficient anti-jamming rateless coding based on cognitive Orthogonal Frequency Division Multiplexing (OFDM) modulation in Cognitive Radio Network (CRN) is mainly discussed. Rateless coding with small redundancy and low complexity is presented, and the optimal design methods of building rateless codes are also proposed. In CRN, anti-jamming rateless coding could recover the lost packets in parallel channels of cognitive OFDM, thus it protects Secondary Users (SUs) from the in-terference by Primary Users (PUs) efficiently. Frame Error Rate (FER) and throughput performance of SU employing anti-jamming rateless coding are analyzed in detail. Performance comparison between rateless coding and piecewise coding are also presented. It is shown that, anti-jamming rateless coding provides low FER and Word Error Rate (WER) performance with uniform sub-channel selection. Meanwhile, it is also verified that, in higher jamming rate and longer code redundancy scenario, rateless coding method could achieve better FER and throughput performance than another anti-jamming coding schemes.

类风湿性关节炎滑膜病变高频超声表现与Anti-ccp、ESR及CRP的相关性

目的分析类风湿性关节炎(RA)滑膜病变高频超声表现与抗环瓜氨酸肽抗体(Anti-CCP)、红细胞沉降率(ESR)和C反应蛋白(CRP)的相关性,以期为该疾病早期诊断及治疗方案的制定提供更为准确和科学的依据。方法选取2020年1月至2023年3月于大庆龙南医院风湿免疫科住院的治疗前RA患者65例(RA组),另选取同期于本院体检中心行体检的健康者55名(对照组)。比较两组高频超声表现、髌上囊液体厚度、滑膜厚度、滑膜动脉RI及实验室指标(Anti-ccp、ESR及CRP水平),RA组根据Anti-ccp、ESR及CRP阳性标准分为阳性、阴性组,比较Anti-ccp、ESR及CRP阳性及阴性组的髌上囊液体厚度、滑膜厚度、滑膜动脉RI。采用Pearson分析滑膜病变高频超声表现各指标与Anti-ccp、ESR及CRP的相关性。结果对照组膝积液少<4 mm;RA组80%膝积液>4 mm,多对称,尤见于内外侧隐窝。对照组滑膜难辨,RA组滑膜增厚、低回声、分界清、表面糙、见绒毛。彩超示RA组81.53%膝滑膜有明显血流信号,多为Ⅱ、Ⅲ级。RA组髌上囊液体厚度、滑膜厚度、Anti-ccp、ESR及CRP水平均高于对照组,滑膜动脉RI则低于对照组,差异有统计学意义(P<0.05);Anti-ccp、ESR及CRP阳性组髌上囊液体厚度、滑膜厚度水平均显著高于阴性组,滑膜动脉RI低于阴性组,差异有统计学意义(P<0.05)。髌上囊液体厚度、滑膜厚度与Anti-ccp、ESR及CRP水平均呈正相关(P<0.05);滑膜动脉RI与Anti-ccp、ESR及CRP水平均呈负相关(P<0.05)。结论高频超声可清晰观察RA患者的滑膜病变情况,且与Anti-ccp、ESR及CRP等实验室指标存在显著关联性,可为临床诊断RA滑膜病变患者提供有力的参考依据,利于制定更具针对性的治疗措施。

类风湿关节炎合并骨关节炎病人血清anti-Sa、anti-CCP水平与骨关节损伤、全身炎症反应的相关性分析

目的:分析类风湿关节炎(RA)病人血清anti-Sa、anti-CCP抗体水平与其骨关节损伤、全身炎症反应的相关性。方法:选择RA合并骨关节损伤病人108例,根据血清anti-Sa、anti-CCP抗体水平分别列入高anti-Sa组和低anti-Sa组、高anti-CCP组和低anti-CCP组。比较各组病人WOMAC骨性关节炎指数、lysholms膝关节功能评分值,血清白细胞介素(IL)-1β、IL-6、IL-27、肿瘤坏死因子α(TNF-α)水平。采用Pearson检验评估有关指标的相关性。结果:高anti-Sa组、高anti-CCP组病人的WOMAC骨性关节炎指数明显高于低anti-Sa组(P<0.01),lysholms膝关节功能评分明显低于低anti-Sa组(P<0.01);血清中IL-1β、IL-6、IL-27、TNF-α的水平明显高于低anti-CCP组(P<0.01)。RA病人血清anti-Sa、anti-CCP抗体水平与骨关节损伤、全身炎症反应严重程度呈正相关关系(P<0.05~P<0.01),与lysholms膝关节功能评分呈负相关关系(P<0.01)。结论:RA病人血清中anti-Sa、anti-CCP抗体水平显著升高与关节损伤及全身炎症反应有一定的相关性,可作为临床判断病情活动性与骨关节损伤的参考指标。

血清anti-β2GPI、FSTL1、PD-1对系统性红斑狼疮免疫功能、疾病活动度的影响

目的探究血清抗β2糖蛋白I抗体(anti-β2GPI)、卵泡抑素样蛋白(FSTL1)、程序性死亡受体1(PD-1)对系统性红斑狼疮(SLE)患者免疫功能、疾病活动度的影响。方法选取我院2019年1月~2022年6月SLE患者113例作为观察组,另选取同期健康体检者105例作为对照组。比较两组、不同疾病活动度患者血清anti-β2GPI、FSTL1、PD-1水平,评价各血清指标与疾病活动度的关系,并根据观察组血清表达水平分为高表达者、低表达者,对比两者免疫功能(CD4+、CD8+、CD4+/CD8+),分析各血清指标与免疫功能相关性。结果观察组血清anti-β2GPI、FSTL1、PD-1高于对照组(P<0.05);血清anti-β2GPI、FSTL1、PD-1高表达患者CD4+、CD4+/CD8+低于低表达患者,CD8+高于低表达患者(P<0.05);血清anti-β2GPI、FSTL1、PD-1与CD4+、CD4+/CD8+呈负相关,与CD8+呈正相关(P<0.05);血清anti-β2GPI、FSTL1、PD-1水平随疾病活动度增加呈升高趋势,且重度活动患者>中度活动患者>轻度活动患者>病情稳定患者(P<0.05);血清anti-β2GPI、FSTL1、PD-1与疾病活动度显著相关(P<0.05)。结论血清anti-β2GPI、FSTL1、PD-1高表达可能参与SLE患者细胞免疫功能紊乱、疾病活动度加重的发生过程。

Assessment of Liver Fibrosis in HBsAg-Negative and Anti HBc Positive Patients

Background: Surface antigen (HBsAg) is the mean marker of hepatitis B virus infection. During the course of the infection, some patients lose the HBsAg and only the presence of anti-HBc antibody indicates previous contact with the virus. Among these patients, some have detectable viral load (occult infection) but most without viral replication. There is no guideline regarding these patients. The aim of this study was to assess hepatic fibrosis in patients with only the hepatitis B virus contact marker “total anti-HBc”. Patients and methods: it was a descriptive and analytical cross-sectional study, conducted in three private hospitals from January to August 2022. Were included HBsAg-negative and HBc-positive patients, consulting in Gastroenterology departments. Noninvasive methods (APRI, FIB-4 and FIBROSCAN) were used to evaluate liver stiffness because of their easy accessibility and low-cost. The hepatic fibrosis was considered significant when the score determined by APRI, FIB-4 and FIBROSCAN® tests was respectively greater than 1.5;2.67 and 8 kPa corresponding to fibrosis level 2 (F2). Results: A total of 63 HBsAg-negative/total HBcAg-positive patients were included. The mean age was 49.9 ± 13.4 years. The male/female sex ratio was 1.78. Of the 63 patients, 19 had significant liver fibrosis (30.1%) among which 9 patients had HCC. The FIB-4 score outperformed the APRI score in assessing liver fibrosis, with a sensitivity of 84.2%, a specificity of 100% and a negative predictive value of 93.6%. In univariate analysis, there was a significant association between the occurrence of significant liver fibrosis and age over 40 years, dyslipidaemia, obesity, alcohol consumption, smoking, herbal medicine, negative anti-HBs immunological status and detectable viral load. Conclusion: Our study revealed a high prevalence of significant to severe hepatic fibrosis in anti-HBc positive patients. In most of the cases, the fibrosis was severe. Progression to HCC has also been possible. There is no consensus on the follow-up strategy for those patients. However, screening for hepatic fibrosis using noninvasive methods should be recommended for patients aged over 40 years, alcohol or herbal medicine users, patients with metabolic syndrome or occult hepatitis B. In HBsAg-negative/anti-HBc-positive patients, liver stiffness should be evaluated and if it is greater than F2, HCC screening should be started.

Anti-GM1影响裸鼠NK细胞分化和杀伤活性研究

目的研究抗单唾液酸神经节苷脂抗体(Anti-GM1)通过调节自然杀伤(NK)细胞分化,抑制裸鼠NK细胞的自然杀伤活性。方法多重免疫荧光染色鉴定人肾癌组织中NK细胞的分型特点。选择雄性BALB/c小鼠6只,GM1皮下注射每周1次,一共三周,以此来免疫小鼠制备Anti-GM1。选取6只BALB/c-Nude裸鼠,采用随机数字表法将裸鼠分为对照组(CON组)及实验组(Anti-GM1组),CON组用IgG连续腹腔注射7 d;Anti-GM1组用Anti-GM1连续腹腔注射7 d。7 d后经颈椎脱臼法处死裸鼠,取裸鼠脾脏并制成单细胞悬液,将脾细胞与YAC-1细胞共培养4 h。用LDH法检测NK细胞的杀伤活力。使用流式细胞术进行检测,根据CD27和CD11b表达来界定NK细胞亚群,同时检测CD107a的表达情况。ELISA检测NK细胞的γ干扰素(IFN-γ)及颗粒酶B(GzmB)分泌水平。结果人肾癌组织标本中有明显的NK细胞浸润现象,并且GzmB也呈现阳性表达。Anti-GM1可以显著抑制NK细胞的杀伤活力。与CON组相比,Anti-GM1组可以促进NK细胞向成熟亚群进行分化。Anti-GM1组NK细胞的CD107a水平显著下降。Anti-GM1组NK细胞的IFN-γ及GzmB分泌水平较CON组下降。结论NK细胞可以浸润在人肾癌组织中,并且能够分泌GzmB,发生自然杀伤作用。Anti-GM1可以促进NK细胞的成熟,但抑制NK细胞的杀伤活力,与其抑制NK细胞CD107a表达和抑制NK细胞的IFN-γ及GzmB分泌有关。

Tumor-infiltrating T-Lymphocyte immunity-related immune tolerance and anti–programmed cell death protein 1/ligand of programmed cell death protein 1 therapy for advanced hepatocellular carcinoma

Systemic therapy has become the standard treatment for patients with advanced hepatocellular carcinoma(HCC)whose treatment options are limited.However,the long-term patient response to drugs and the survival outcomes remain a concern.With increasing exploration of the HCC microenvironment,particularly in terms of T lymphocyte immunity,a new era of immunomolecular targeted therapy,based on molecular signaling,has arrived for advanced HCC.In the study of immune tolerance of the intrinsic HCC microenvironment,we found that multiple immunosuppressive mechanisms and immune checkpoint inhibitors,such as anti–programmed cell death protein 1/ligand of programmed cell death protein 1 therapy,have improved clinical outcomes in some patients with advanced HCC.Furthermore,various combination therapies have been investigated,and HCC types have been categorized into different types based on anti–programmed cell death protein 1(PD-1)/ligand of programmed cell death protein 1(PD-L1)treatment.In this paper,we first discuss the tumor-infiltrating T lymphocyte immunity and immune tolerance of HCC.We then clarify the basic mechanism of anti–PD-1/PD-L1 therapy and discuss the types of HCC based on anti–PD-1/PD-L1 therapy.Thereafter,we explain the relevant studies and mechanisms of combination therapy of anti–PD-1/PD-L1 with antiangiogenesis drugs or multikinase kinase inhibitors,anti–T lymphocyte–related signaling pathways in HCC,and other anti-CD8+T cell immune checkpoints.In this way,this review offers a deeper understanding of anti–PD-1/PD-L1 immunotherapy for advanced HCC,in order to provide better individualized treatments for patients with advanced HCC.

Antibody Pattern: Correlation of Age and Gender in ANA and Anti-ds-DNA Prevalence

The study was designed to find the prevalence of ANA antibodies and anti-dsDNA antibodies in samples tested at AFIP Rawalpindi and their correlation with age and gender and to find positive and negative predictive values of ANA antibodies.For this purpose,twelve thousand nine hundred sixty-seven(12,967)patients were analyzed for ANA with four hundred sixty-eight(468)healthy samples tested as control and four thousand seven hundred three(4,703)patients tested for ds-DNA antibodies.Retrospective data of all samples tested by indirect immunofluorescence(IF)for ANA antibodies and dsDNA antibodies was collected.To address positive and negative predictive values another control group(autoimmunity not suspected)of serum samples was taken from the healthy population.For the first group,age,gender,ANA antibodies and ds-DNA antibodies results(both tests performed by IIF)data was collected from a computer record cell;for the second control group,ANA antibodies were performed by IIF.12,967 and 4,703 samples(Group 1)were tested for ANA antibodies and dsDNA antibodies,respectively,during this period.1,119(9%)and 99(2%)were found positive for ANA antibodies and ds DNA antibodies.Among these positive samples,850(76%)and 73(74%)were females respectively.Gender predisposition towards autoimmunity(ANA)was found significant with a P value of(P=0.001).Relation of age was also found significant with anti-ANA antibodies with a P value of(P=0.001).This study shows a negative correlation between age(P=0.025)and gender(P=0.001)with anti-dsDNA which is also significant.High prevalence was found below the mean age of 38 years(SD±16.635)for ANA antibodies and the mean age of 35 years(SD±15.066)for ds-DNA antibodies.The age of ANA antibodies and dsDNA antibodies positive patients ranged from 1 year old to 98 years old and 2 years old to 95 years old respectively.In the second(autoimmunity-free)control group,a total of 468 samples were tested for ANA antibodies and 9(2%)were found positive.Positive predictive value(PPV)was 8.6%and negative predictive value(NPV)was 98%.ANA is a sensitive test for autoimmunity and it is significantly related to female gender and increasing age.The low prevalence of ANA antibodies among clinically suspected cases suggests that rationalization of test prescriptions is needed.Anti-ds-DNA is also a sensitive test for diagnosis of SLE and it is significantly related to female gender and increasing age.

基于特征信息融合预测Anti-CRISPR蛋白

CRISPR-Cas系统是一种存在于细菌和古细菌中的获得性免疫系统,作为基因编辑工具在癌症治疗等方面被广泛研究,但CRISPR-Cas基因编辑技术存在基因脱靶效应。研究发现,Anti-CRISPR蛋白是一种可以调节CRISPR-Cas系统功能的蛋白质,在不破坏靶向基因编辑的情况下,可以减少脱靶效应等不良影响,从而提高基因编辑技术的效率和安全性。因此,研究Anti-CRISPR蛋白对于理解CRISPR-Cas系统的功能和细菌-病毒相互作用具有重要意义。本文构建了Anti-CRISPR蛋白数据集,提取氨基酸组分、氨基酸二肽组分、g-gap二肽组成、蛋白质二级结构、平均化学位移和蛋白质骨架6种特征参数,利用支持向量机对Anti-CRISPRs蛋白进行预测,在Jackknife检验下,单特征参数最高预测成功率为93.50%;对维度过高的氨基酸二肽组分和g-gap二肽组成分别进行降维处理,得到g-gap二肽组成在g=3、维数是121维时预测成功率最高,为95.10%,进一步研究发现有16种g-gap二肽组合对应11种氨基酸与Anti-CRISPR蛋白预测相关度较大;最后对特征参数进行融合,融合后最高预测成功率为96.07%。

基于YOLOv5s-AntiUAV的反无人机目标检测算法研究

随着无人机的应用领域不断拓展,无人机的“黑飞”给公共安全造成严重损害。为解决侵入式无人机小目标在复杂飞行环境下的错检和漏检问题,提出基于YOLOv5s-AntiUAV的反无人机目标检测算法。首先,引入结合深度超参数卷积的Slim-Neck范式,增强算法特征提取能力并保持计算效率。其次,在骨干和颈部网络引入SPD-Conv模块,提高在低分辨率图像中小目标的检测性能。最后,用Alpha-CIoU替换YOLOv5s算法中的CIoU,增强算法泛用性。YOLOv5s-AntiUAV算法与YOLOv5s、SSD和Faster R-CNN算法在数据集Anti-UAV上的对比实验结果表明,改进算法的mAP@0.5值分别增长了1.1、12.1和4.9个百分点,凸显其实用性。由在VisDrone2019数据集上进行的迁移实验显示,相较于YOLOv5s算法,改进算法mAP@0.5值提升了4.5个百分点,表明其相较于原算法具有更强的鲁棒性。

Antibacterial, Anti-Inflammatory and Antioxidant Activities of an ACAZY Herbal Formula Used in Traditional Medicine to Treat Respiratory Infections

ACAZY is a plant formula used in traditional medicine in Burkina Faso to treat respiratory infections. After phytochemical analysis, this study evaluated extracts’ anti-inflammatory, antioxidant and antibacterial properties from the ACAZY recipe. Three extractions, an aqueous macerate (AM), an aqueous decoction (AD) and an hydroethanolic macerate (HEM) of the ACAZY recipe powder were carried out. Phytochemical screening of the extracts was carried out using high-performance thin-layer chromatography (HPTLC) and the determination of phenolic compounds. The anti-inflammatory potential was assessed in vitro using pro-inflammatory enzyme inhibition tests. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and Ferric-reducing antioxidant power (FRAP) antioxidant properties were also determined. The antibacterial activity was evaluated on Staphylococcus aureus and Streptococcus pneumoniae strains. Phytochemical analysis revealed the presence of flavonoids, saponins, tannins, anthracenosids, sterols and triterpenes in the extracts. The extracts inhibited pro-inflammatory enzymes by more than 40% at only 100 µg/mL. The extracts also showed potent antibacterial activity with a minimum inhibitory concentration 1 mg/mL on Staphylococcus aureus and 2 mg/mL on Streptococcus pneumoniae. The extracts in the ACAZY formula have shown anti-inflammatory and antioxidant properties in vitro. The AD also showed an antibacterial activity. This justifies its use in traditional medicine to treat acute respiratory infections.

Safety and in Vivo Anti-Inflammatory Activity of Ethanolic Extract of Ficus umbellata (Vahl.) Leaves

Toxicity is the totality of adverse effects, which can be functional and morphological lesions in a living organism, caused by a substance introduced in relatively high single doses or in small, repeated doses. The aim of this study was to assess the OECD-recommended acute oral toxicity and anti-inflammatory activity of ethanolic extract of Ficus umbellata leaves. Animals were given a single oral dose of 1000, 3000 and 5000 mg/Kg body weight (BW) of the extract. For the anti-inflammatory activity test, rats were given the ethanolic extract of F. umbellata leaves at doses of 100, 300 and 500 mg/Kg or aspirin® at a concentration of 100 mg/Kg PC orally, one hour before injection of 0.05 ml of 1% formalin under the plantar fascia of the rat’s right hind paw. Paw volume measurements were taken one, two and three hours after formalin injection, using an electronic caliper. After 14 days of observation, no deaths were observed in treated rats. The LD50 of ethanolic extract of Ficus umbellata leaf powder is greater than 5000 mg/Kg body weight. This extract has no significant effects on hematological parameters and on the main markers of nephrotoxicity and hepatotoxicity for a single dose of less than 5000 mg/Kg PC. It reduces formalin-induced edema. Evaluation of the percentage inhibition showed that the extract had greater anti-inflammatory activity at 3 hours after the start of the experiment. However, better inhibition of inflammatory oedema of the paw of rats treated with 500 mg/Kg was observed at 5 hours after the start of the experiment, with a percentage inhibition of 69.23 ± 1.02, compared with the reference group treated with aspirin® 100 mg/Kg, which showed an inhibition of 63.50 ± 0.98. These results show that F. umbellata leaves possess anti-inflammatory activity, which would justify their use in traditional African medicine to prevent or treat inflammation.

轮图中三类特殊子图的anti-Ramsey数

在边染色图中,如果某个子图的每条边都染不同的颜色,则称该子图是彩虹的。给定图G和H,对图G的一个k边染色若存在最大的正整数R,使得G中不包含彩虹的H作为子图,则将H的anti-Ramsey数记为ar(G,H)。当主图为轮图时,给出了Theta图、星图和双星图anti-Ramsey数的精确值。

Implications for Antigravity Tests of Dirac’s Negative Energy Antiparticles

P. A. M. Dirac conceived antimatter in 1928 as having negative energy by allowing a consistent representation of matter-antimatter annihilation into light. To achieve compatibility with special relativity, particle physics of the early 20th century made the theoretical assumption that antiparticles have positive energy, an assumption that remains in effect as of today. In this note we prove apparently for the first time a theorem stating that positive mass antiparticles violate Dirac’s particle-antiparticle annihilation into light. We then show the consequential unsettled character of the recent gravity test of the anti-Hydrogen atom due to the positive mass of its nucleus. We conclude by suggesting that a final scientific claim on matter-antimatter gravity requires tests on particles with clear antimatter character, such as the 1994 resolutory proposal for the comparative test of the gravity of very low energy electron and positron in horizontal flight on a supercooled vacuum tube.