Relative orbit determination algorithm of space targets with passive observation

Angles-only relative orbit determination for space non-cooperative targets based on passive sensor is subject to weakly observable problem of the relative state between two spacecraft. Previously, the evidence for angles-only observability was found by using cylindrical dynamics, however, the solution of orbit determination is still not provided. This study develops a relative orbit determination algorithm with the cylindrical dynamics based on differential evolution. Firstly, the relative motion dynamics and line-of-sight measurement model for nearcircular orbit are established in cylindrical coordinate system.Secondly, the observability is qualitatively analyzed by using the dynamics and measurement model where the unobservable geometry is found. Then, the angles-only relative orbit determination problem is modeled into an optimal searching frame and an improved differential evolution algorithm is introduced to solve the problem. Finally, the proposed algorithm is verified and tested by a set of numerical simulations in the context of highEarth and low-Earth cases. The results show that initial relative orbit determination(IROD) solution with an appropriate accuracy in a relative short span is achieved, which can be used to initialize the navigation filter.

TLE orbit determination using simplex method

Two-Line Element(TLE)datasets are the only orbital data source of Earth-orbiting space objects for many civil users for their research and applications.The datasets have uneven qualities that may affect the reliability of the propagated positions of space objects using a single TLE.The least squares approach to use multiple TLEs also suffers from the poor quality of some TLEs,and reliable error information cannot be available.This paper proposes a simplex algorithm to estimate an optimal TLE from multiple TLEs and obtain the uncertainty of each element.It is a derivative-free technique that can deal with various orbit types.Experiments have demonstrated that using the TLE estimated from the simplex method is more reliable,stable,and effective than those from the batch least squares method.As an application example,the optimal TLE and its uncertainty are used for predicting the fallen area,keeping the actual fallen site in the prediction areas.

ORBIT评分与HAS-BLED评分对心脏瓣膜置换术后华法林抗凝出血风险的预测价值比较

目的比较ORBIT评分与HAS-BLED评分对心脏瓣膜置换术后华法林抗凝出血风险的预测价值。方法回顾性分析304例心脏瓣膜置换术后需行华法林抗凝治疗患者的病例资料,分别根据ORBIT评分和HAS-BLED评分对患者进行风险分层和分组,分析基于不同评分的风险分层与术后华法林抗凝出血事件的相关性,比较2种评分方法风险分层的一致性及其对出血事件的预测价值。结果304例患者中,出血患者32例、未出血患者272例,出血患者的术后ORBIT评分、HAS-BLED评分均高于未出血患者,差异有统计学意义(P<0.05)。基于ORBIT评分划分的中危、高危患者的出血风险分别为低危患者的6.092(95%CI:2.694~13.775)倍、9.373(95%CI:1.465~59.943)倍,基于HAS-BLED评分划分的中危、高危患者的出血风险分别为低危患者的3.750(95%CI:1.383~10.166)倍、14.250(95%CI:5.489~36.995)倍。受试者工作特征曲线分析结果显示,ORBIT评分预测华法林抗凝出血风险的曲线下面积(AUC)为0.646(95%CI:0.589~0.699),敏感度为46.88%,特异度为87.87%,最佳截断值为3分;HAS-BLED评分预测华法林抗凝出血风险的AUC为0.768(95%CI:0.717~0.814),敏感度为75.00%,特异度为69.85%,最佳截断值为2分;Delong检验结果显示,2种评分的AUC差异有统计学意义(D=0.122,95%CI:0.001~0.245,Z=1.962,P<0.05)。结论ORBIT评分和HAS-BLED评分对心脏瓣膜置换术后华法林抗凝出血风险均具有一定预测价值,其中HAS-BLED评分的预测效能更优。

Theory for Charge Density Wave and Orbital-Flux State in Antiferromagnetic Kagome Metal FeGe

We theoretically study the charge order and orbital magnetic properties of a new type of antiferromagnetic kagome metal FeGe.Based on first-principles density functional theory calculations,we study the electronic structures,Fermi-surface quantum fluctuations,as well as phonon properties of the antiferromagnetic kagome metal FeGe.It is found that charge density wave emerges in such a system due to a subtle cooperation between electron-electron interactions and electron–phonon couplings,which gives rise to an unusual scenario of interaction-triggered phonon instabilities,and eventually yields a charge density wave(CDW)state.We further show that,in the CDW phase,the ground-state current density distribution exhibits an intriguing star-of-David pattern,leading to flux density modulation.The orbital fluxes(or current loops)in this system emerge as a result of the subtle interplay between magnetism,lattice geometries,charge order,and spin-orbit coupling(SOC),which can be described by a simple,yet universal,tight-binding theory including a Kane-Mele-type SOC term and a magnetic exchange interaction.We further study the origin of the peculiar step-edge states in FeGe,which sheds light on the topological properties and correlation effects in this new type of kagome antiferromagnetic material.

p-d Orbital Hybridization Engineered Single-Atom Catalyst for Electrocatalytic Ammonia Synthesis

The rational design of metal single-atom catalysts(SACs)for electrochemical nitrogen reduction reaction(NRR)is challenging.Two-dimensional metal-organic frameworks(2DMOFs)is a unique class of promising SACs.Up to now,the roles of individual metals,coordination atoms,and their synergy effect on the electroanalytic performance remain unclear.Therefore,in this work,a series of 2DMOFs with different metals and coordinating atoms are systematically investigated as electrocatalysts for ammonia synthesis using density functional theory calculations.For a specific metal,a proper metal-intermediate atoms p-d orbital hybridization interaction strength is found to be a key indicator for their NRR catalytic activities.The hybridization interaction strength can be quantitatively described with the p-/d-band center energy difference(Δd-p),which is found to be a sufficient descriptor for both the p-d hybridization strength and the NRR performance.The maximum free energy change(ΔG_(max))andΔd-p have a volcanic relationship with OsC_(4)(Se)_(4)located at the apex of the volcanic curve,showing the best NRR performance.The asymmetrical coordination environment could regulate the band structure subtly in terms of band overlap and positions.This work may shed new light on the application of orbital engineering in electrocatalytic NRR activity and especially promotes the rational design for SACs.

Comparison between local-made and imported porous polyethylene orbital implant:a randomized controlled equivalence trial and multicenter study

AIM:To compare the exposure rate,infection rate,percentage of enhancement,and success rate between Medpor and the three-dimensional printed polyethylene(3DP-PE)orbital implant in a preliminary report.METHODS:This prospective,randomized,equivalence,controlled trial was conducted at two institutes.The equivalent margin was±10%.The sample size for the equivalence trial was 174 participants per group.Patients who were eligible for enucleations received either Medpor or 3DP-PE implants based on a randomized block of six.The surgeries were performed by five oculoplastic surgeons.The assessor and patients were masked.The magnetic resonance imaging(MRI)of the orbit was performed at least 6mo after operation and the fibrovascular ingrowth was analyzed using the Image J software.Follow-up continued at least 1y after surgery.The intention to treat and per protocol approaches were used.RESULTS:Totally 128 patients met the criteria in the report.Fifty Medpor and 553DP-PE cases completed the trial.The most common cause of blindness was trauma.The mean follow-up times of Medpor and 3DP-PE were 33 and 40mo respectively.The exposure rate was not statistically significant between two groups(6.0%and 7.3%),P<0.05,95%CI(-9.8%,+12.0%).The success rates were 94%(Medpor)and 92.7%(3DP-PE).No postoperative infection was reported.Nine patients had MRI tests and two had implant exposures with 66.3% enhancement at 75mo(Medpor)and 58% enhancement at 57mo(3DP-PE)postoperatively.CONCLUSION:There is no statistically significant difference in exposure rate and success rate between Medpor and 3DP-PE in enucleation in the report.However,we cannot conclude that they are equivalent in terms of the exposure rate and success rate because the 95%CI is wider than±10%.The infection rate is equivalent in both groups.

Late infection after peri-orbital autologous micro-fat graft:a case presentation and literature review

Citation:Pakdel F,Asadigandomani H,Arab Bafrani M,Nozarian Z,Abedinifar Z,Pirmarzdashti N,Jafari B,Siami Z.Late infection after peri-orbital autologous micro-fat graft:a case presentation and literature review.Int J Ophthalmol 2024;17(3):603-606.

High-Resolution Recognition of Orbital Angular Momentum Modes in Asymmetric Bessel Beams Assisted by Deep Learning

Fractional orbital angular momentum(OAM) vortex beams present a promising way to increase the data throughput in optical communication systems. Nevertheless, high-precision recognition of fractional OAM with different propagation distances remains a significant challenge. We develop a convolutional neural network(CNN)method to realize high-resolution recognition of OAM modalities, leveraging asymmetric Bessel beams imbued with fractional OAM. Experimental results prove that our method achieves a recognition accuracy exceeding 94.3% for OAM modes, with an interval of 0.05, and maintains a high recognition accuracy above 92% across varying propagation distances. The findings of our research will be poised to significantly contribute to the deployment of fractional OAM beams within the domain of optical communications.

Bone destruction of orbital wall in idiopathic orbital inflammatory pseudotumor:does it always imply malignancy?

AIM:To assess the clinical presentations and outcomes of idiopathic orbital inflammatory pseudotumor(IOIP)patients with orbital wall bone destruction(OWBD)and to propose an expanded classification system that includes bone destruction.METHODS:The study retrospectively reviewed clinical presentations,imaging findings,treatment modalities,and outcomes of six patients diagnosed histopathologically with IOIP and OWBD at the Beijing Tongren Hospital,Capital Medical University between October 2018 and June 2021.RESULTS:Over two years,6(10%)of 60 IOIP patients at our hospital exhibited OWBD,but this may overrepresent severe cases.The cohort consisted of three men and three women,aged 17 to 60y(mean 35.5±16.1y).Presenting symptoms included proptosis,eyelid swelling,decreased visual acuity with pain,and palpable mass.Imaging revealed multiple anatomical structures involved with the medial wall being the most common site of bone destruction.Histopathological examination showed classic type in five patients and sclerosing type in one patient.All patients underwent surgical resection followed by methylprednisolone treatment.Follow-up(mean 30.3±3.1mo)indicated three patients had no recurrence,while others had varying degrees of symptom persistence or recurrence.CONCLUSION:IOIP with bone destruction is a rare but significant subtype that mimics malignancy,leading to potential diagnostic and therapeutic challenges.Our findings suggest that complete surgical resection combined with adjunctive glucocorticoid therapy can yield favorable outcomes.However,larger-scale studies are needed to further optimize therapeutic approaches.

Orbital-Ordering Driven Simultaneous Tunability of Magnetism and Electric Polarization in Strained Monolayer VCl_(3)

Two-dimensional(2D)van der Waals magnetic materials have promising and versatile electronic and magnetic properties in the 2D limit,indicating a considerable potential to advance spintronic applications.Theoretical predictions thus far have not ascertained whether monolayer VCl_(3) is a ferromagnetic(FM)or anti-FM monolayer;this also remains to be experimentally verified.We theoretically investigate the influence of potential factors,including C_(3) symmetry breaking,orbital ordering,epitaxial strain,and charge doping,on the magnetic ground state.Utilizing first-principles calculations,we predict a collinear type-Ⅲ FM ground state in monolayer VCl_(3) with a broken C_(3) symmetry,wherein only the former two of three t_(2g)orbitals(a_(1g),e_(g2)^(π)and e_(g1)^(π))are occupied.The atomic layer thickness and bond angles of monolayer VCl_(3) undergo abrupt changes driven by an orbital ordering switch,resulting in concomitant structural and magnetic phase transitions.Introducing doping to the underlying Cl atoms of monolayer VCl_(3) without C_(3) symmetry simultaneously induces in-and out-of-plane polarizations.This can achieve a multiferroic phase transition if combined with the discovered adjustments of magnetic ground state and polarization magnitude under strain.The establishment of an orbital-ordering driven regulatory mechanism can facilitate deeper exploration and comprehension of magnetic properties of strongly correlated systems in monolayer VCl_(3).

Sex Determination in Homo sapiens as a Multi-Step Process: Potential for Development of Variants and Sex Differences in Disease Risk

Reproduction via cis-binary mechanisms appears to have evolved fairly early in the evolution of complex organisms, and a system committed to prior to evolution of humans. While the evolution of a chromosomal-specific approach has been a successful strategy for survival of a large variety of species including humans, the fidelity of sex determination leading to 100% cis-binary outcomes is not achieved in many species, with evidence for homosexual or bisexual behaviour evident in more than 1500 species. Thus, such outcomes indicates that sex determination is a multi-step process and not a single event, and as such, could lead to the appearance of variants during the process which developed much earlier than humans. Variants could arise either due to intrinsic variation in the steps of determination, or also be influenced by environmental factors of a biological or psychological nature. In contrast to homosexual variants which do not require interventions such as hormone therapy or surgery, expression of gender dysphoria, is more based in psychology, but also has biological underpinnings and can be influenced by such hormonal interventions and surgery. While the numbers of those with gender dysphoria is small (~0.6% - 1.0% of population), the attention given to this issue raises the possibility of biological and psychological environmental factors impacting the emergence of some of those expressing gender dysphoria. Furthermore, transitioning from male-to-female or female-to-male can have consequences regarding disease risks latter in life, including the appearance of autoimmune diseases. This review will attempt to review some of the evidence regarding sex determination, discuss why the system has potentially not been improved upon during evolution, how a potential role for sex chromosome function on neurodevelopment may be central to variation in humans, and how commitment to the current strategy is likely integrated into other sex-related events such as puberty, pregnancy, and menopause to ensure species survival. It will also discuss how variants in sex determination could contribute to sex differences in disease risk and how epigenetic modifications could play a role in such risk. .

Guidelines for the standardized diagnosis and treatment of non-specific orbital inflammation(2024)

Non-specific orbital inflammation(NSOI)is a noninfectious orbital inflammation.Although it is often considered the most common diagnosis in orbital biopsies,it is an exclusionary diagnosis that requires ruling out systemic disease or other possible causes.Its characteristics include acute orbital signs and symptoms,including pain,proptosis,periorbital edema,chemosis,diplopia,and visual impairment.The clinical manifestations and histological findings of NSOI are heterogeneous,without specific diagnostic criteria or treatment guidelines,which poses significant challenges for diagnosis and treatment.This guideline provides a detailed description of the definition,classification,diagnosis,and treatment of NSOI.

Prognostic factors and clinical features of rhino-orbitalmucormycosis cases:an update for patient and visual survivals

AIM:To determine the frequency of patients’vision survival and prognostic factors and evaluate clinical features in rhino-orbital mucormycosis.METHODS:Forty-three eyes of 43 patients followed up with orbital mucormycosis infections were included in the study.Demographic characteristics of the patients,symptoms at admission,ophthalmologic and non-ophthalmologic examination findings,clinical findings during follow-up,medical and surgical procedures,and complications were recorded.Patient survival was determined by assessing the incidence of mortality,and vision survival was defined as achieving a final visual acuity of at least light perception.RESULTS:Twenty-seven(62.8%)patients were male,and 16(37.2%)were female.When the underlying disease status of the patients was examined,it was observed that all patients had an underlying disease and diabetes constituted the majority(65.2%).Periorbital swelling(69.8%)and ophthalmoplegia(53.5%)were the most common symptoms and findings at the admission of patients with mucormycosis infection.The disease resulted in death in 22(51.2%)patients.The presence of fever and shorter duration of antifungal therapy were associated with lower patient survival.Exenteration surgery was not found to be associated with the survival of the patients.Frozen eye,loss of pupillary light reflex,and development of central retinal artery occlusion were associated with lower vision survival.CONCLUSION:This study presents one of the most extensive patient series in the literature on rhino-orbital mucormycosis.Knowing the patients’symptoms at the time of admission and the clinical findings during the infection process will increase awareness about the disease.

Silencing transformer and transformer-2 in Zeugodacus cucurbitae causes defective sex determination with inviability of most pseudomales

transformer is a switch gene for sex determination in many insects, which cooperates with transformer-2 that is expressed in both sexes to regulate female differentiation, particularly in dipterans. Zeugodacus cucurbitae(Coquillett) is a very destructive pest worldwide, however, its sex determination pathway remains largely uncharacterized. Here, we show that the female sex ratio is sharply reduced with knockdown of either transformer or transformer-2 by RNA interference in early embryos of Z. cucurbitae. Most of the males grown from the embryos with transient transformer and transformer-2 suppression mated with wild-type females and produced mixed sex progeny, with one exception that produced only female progeny, and all of the few remaining males failed to mate with wild-type females and produced no progeny. The exceptional male and those males with mating failure were XX pseudomales as determined by the detection of Y chromosome-linked Maleness-on-the-Y, indicating that most XX pseudomales are not viable. The phenotypes of transformer and transformer-2 suggest that they play a key role in regulating sex determination and are required for female sexual development of Z. cucurbitae. Our results will be beneficial to the understanding of sex determination in Z. cucurbitae and can facilitate the development of genetic sexing strains for its biological control.

Effect of navigation endoscopy combined with threedimensional printing technology in the treatment of orbital blowout fractures

●AIM:To explore the combined application of surgical navigation nasal endoscopy(NNE)and three-dimensional printing technology(3DPT)for the adjunctive treatment of orbital blowout fractures(OBF).●METHODS:Retrospective analysis was conducted on the data of patients with OBF who underwent surgical treatment at the Affiliated Eye Hospital of Nanchang University between July 2012 and November 2022.The control group consisted of patients who received traditional surgical treatment(n=43),while the new surgical group(n=52)consisted of patients who received NNE with 3DPT.The difference in therapeutic effects between the two groups was evaluated by comparing the duration of the operation,best corrected visual acuity(BCVA),enophthalmos difference,recovery rate of eye movement disorder,recovery rate of diplopia,and incidence of postoperative complications.●RESULTS:The study included 95 cases(95 eyes),with 63 men and 32 women.The patients’age ranged from 5 to 67y(35.21±15.75y).The new surgical group and the control group exhibited no statistically significant differences in the duration of the operation,BCVA and enophthalmos difference.The recovery rates of diplopia in the new surgical group were significantly higher than those in the control group at 1mo[OR=0.03,95%CI(0.01–0.15),P<0.0000]and 3mo[OR=0.11,95%CI(0.03–0.36),P<0.0000]postoperation.Additionally,the recovery rates of eye movement disorders at 1 and 3mo after surgery were OR=0.08,95%CI(0.03–0.24),P<0.0000;and OR=0.01,95%CI(0.00–0.18),P<0.0000.The incidence of postoperative complications was lower in the new surgical group compared to the control group[OR=4.86,95%CI(0.95–24.78),P<0.05].●CONCLUSION:The combination of NNE and 3DPT can shorten the recovery time of diplopia and eye movement disorder in patients with OBF.

Dynamic properties of the magnetic skyrmion driven by electromagnetic waves with spin angular momentum and orbital angular momentum

We theoretically studied the dynamic properties of the skyrmion driven by electromagnetic(EM)waves with spin angular momentum(SAM)and orbital angular momentum(OAM)using micromagnetic simulations.First,the guiding centers of the skyrmion driven by EM waves with SAM,i.e.,left-handed and right-handed circularly polarized EM waves,present circular trajectories,while present elliptical trajectories under linear EM waves driving due to the superposition of oppositely polarized wave components.Second,the trajectories of the skyrmion driven by EM waves with OAM demonstrate similar behavior to that driven by linearly polarized EM waves.Because the wave vector intensity varies with the phase for both linearly polarized EM waves and EM waves with OAM,the angular momentum is transferred to the skyrmion non-uniformly,while the angular momentum is transferred to the skyrmion uniformly for left-handed and right-handed circularly polarized EM driving.Third,the dynamic properties of the skyrmion driven by EM waves with both SAM and OAM are investigated.It is found that the dynamic trajectories exhibit more complex behavior due to the contributions or competition of SAM and OAM.We investigate the characteristics of intrinsic gyration modes and frequency-dependent trajectories.Our research may provide insight into the dynamic properties of skyrmion manipulated by EM waves with SAM or OAM and provide a method for controlling skyrmion in spintronic devices.

Generation of orbital angular momentum hologram using a modified U-net

Orbital angular momentum(OAM)holography has become a promising technique in information encryption,data storage and opto-electronic computing,owing to the infinite topological charge of one single OAM mode and the orthogonality of different OAM modes.In this paper,we propose a novel OAM hologram generation method based on a densely connected U-net(DCU),where the densely connected convolution blocks(DCB)replace the convolution blocks of the U-net.Importantly,the reconstruction process of the OAM hologram is integrated into DCU as its output layer,so as to eliminate the requirement to prepare training data for the OAM hologram,which is required by conventional neural networks through an iterative algorithm.The experimental and simulation results show that the OAM hologram can rapidly be generated with the well-trained DCU,and the reconstructed image's quality from the generated OAM hologram is significantly improved in comparison with those from the Gerchberg-Saxton generation method,the Gerchberg-Saxton based generation method and the U-net method.In addition,a 10-bit OAM multiplexing hologram scheme is numerically demonstrated to have a high capacity with OAM hologram.

Bessel–Gaussian beam-based orbital angular momentum holography

Orbital angular momentum(OAM), as a new degree of freedom, has recently been applied in holography technology.Due to the infinite helical mode index of OAM mode, a large number of holographic images can be reconstructed from an OAM-multiplexing hologram. However, the traditional design of an OAM hologram is constrained by the helical mode index of the selected OAM mode, for a larger helical mode index OAM mode has a bigger sampling distance, and the crosstalk is produced for different sampling distances for different OAM modes. In this paper, we present the design of the OAM hologram based on a Bessel–Gaussian beam, which is non-diffractive and has a self-healing property during its propagation. The Fourier transform of the Bessel–Gaussian beam is the perfect vortex mode that has the fixed ring radius for different OAM modes. The results of simulation and experiment have demonstrated the feasibility of the generation of the OAM hologram with the Bessel–Gaussian beam. The quality of the reconstructed holographic image is increased, and the security is enhanced. Additionally, the anti-interference property is improved owing to its self-healing property of the Bessel-OAM holography.

A Population Dynamics Approach to the Distribution of Space Debris in Low Earth Orbit

The presence of the debris in the Earth’s orbit poses a significant risk to human activity in outer space.This debris population continues to grow due to ground launches,the loss of external parts from space ships,and uncontrollable collisions between objects.A computationally feasible continuum model for the growth of the debris population and its spatial distribution is therefore critical.Here we propose a diffusion-collision model for the evolution of the debris density in the low-Earth orbit and its dependence on the ground-launch policy.We parametrize this model and test it against data from publicly available object catalogs to examine timescales for the uncontrolled growth.Finally,we consider sensible launch policies and cleanup strategies and how they reduce the future risk of collisions with active satellites or space ships.

Manipulating d-d orbital hybridization induced by Mo-doped Co_(9)S_(8) nanorod arrays for high-efficiency water electrolysis

Precisely refining the electronic structure of electrocatalysts represents a powerful approach to further optimize the electrocatalytic performance.Herein,we demonstrate an ingenious d-d orbital hybridization concept to construct Mo-doped Co_(9)S_(8) nanorod arrays aligned on carbon cloth(CC)substrate(abbreviated as Mo-Co_(9)S_(8)@CC hereafter)as a high-efficiency bifunctional electrocatalyst toward water electrolysis.It has experimentally and theoretically validated that the 4d-3d orbital coupling between Mo dopant and Co site can effectively optimize the H_(2)O activation energy and lower H^(*)adsorption energy barrier,thereby leading to enhanced hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)activities.Thanks to the unique electronic and geometrical advantages,the optimized Mo-Co_(9)S_(8)@CC with appropriate Mo content exhibits outstanding bifunctional performance in alkaline solution,with the overpotentials of 75 and 234 mV for the delivery of a current density of 10 mA cm^(-2),small Tafel slopes of 53.8 and 39.9 mV dec~(-1)and long-term stabilities for at least 32 and 30 h for HER and OER,respectively.More impressively,a water splitting electrolylzer assembled by the self-supported Mo-Co_(9)S_(8)@CC electrode requires a low cell voltage of 1.53 V at 10 mA cm^(-2)and shows excellent stability and splendid reversibility,demonstrating a huge potential for affordable and scalable electrochemical H_(2) production.The innovational orbital hybridization strategy for electronic regulation herein provides an inspirable avenue for developing progressive electrocatalysts toward new energy systems.