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Aiming at the difficulty of tracking and recognizing ballistic targets and active multi-false targets in the presence of countermeasures, a joint tracking and recognition method for ballistic targets and false targets based on the robust interacting multiple model (RIMM) strategy is proposed. This method develops the interacting multiple model (IMM) strategy based on the deduced true target and false target motion pattern set and the fine difference features within the set, using the extended Kalman filter (EKF) as sub filters. Additionally, this method introduces probability adjustment factors and time-varying factors into the IMM strategy to update the probability transition matrix in real time and amplify the fine feature difference of the motion pattern set effectively, which not only achieves stable tracking of ballistic targets and false targets, improves the tracking accuracy, but also identifies them online in real time, achieving integrated tracking and identification. Simulation results show that the proposed method has better performance than traditional single model EKF algorithm and classical IMM+EKF algorithm, and it can track and recognize ballistic targets and false targets in real time, which is conducive to improving the efficiency of radar resource scheduling.

The rise of biomimetic unmanned aerial vehicle (UAV) cluster has brought new challenges for radar target tracking and identification. Different cluster flight modes will have different impacts on radar data processing and cluster target identification. For analyzing the influence mechanism of the cluster on radar tracking and identification, this paper models the flight process of UAV cluster based on three kinds of species: geese, wolves and bees, which respectively simulated the large-scale transport, close-in rounding attack and robust information communication of UAV cluster. Secondly, it discusses the influence mechanism of different cluster modes on several algorithms of tracking: track initiation, data association and tracking filter. Finally, combined with the characteristics of three biological movements, it designs the identification methods of cluster event pattern based on clustering in detail, and gives the judgment rules. The simulation results show that there is the suitable combination of radar data processing algorithms for different clustering modes. The optimized tracking algorithm combination based on different clustering modes can effectively improve the tracking accuracy of the radar cluster target, and can reduce the time cost. Moreover, the method proposed in this paper can realize the identification of different cluster patterns to the judgment of target intention and provide the subsequent processing.

The design of waveforms plays a critical role in integrated sensing and communication (ISAC) systems. An ISAC waveform with a 0dB peak‐to‐average power ratio (PAPR) is designed by combining a Golay complementary sequence with a constant envelope orthogonal frequency‐division multiplexing. By adjusting the phase modulation parameters, this waveform allows for a trade‐offs between communication and sensing capabilities. The authors focus on several key performance metrics for the proposed ISAC waveform, notably using mutual information as a holistic performance indicator to assess both sensing and communication effectiveness. Through extensive numerical simulations, the authors demonstrate that the ISAC waveform significantly enhances detection probability compared to traditional phase‐modulated waveforms. The findings suggest that this approach is beneficial for designing low PAPR phase‐modulated ISAC waveforms, enhancing both the functionality and efficiency of ISAC systems. [ABSTRACT FROM AUTHOR]

Myocardial fibrosis is a critical concern in clinical medicine. This study explores the potential of odoratin as a treatment for myocardial fibrosis and investigates its underlying mechanisms. In vitro experiments involved stimulating primary mouse cardiomyocytes with TGF‐β1, followed by odoratin treatment, to assess levels of reactive oxygen species (ROS) and nitric oxide (NO). In vivo, a mouse model of myocardial fibrosis was established using abdominal aortic constriction (AAC) and treated with odoratin. ROS and NO levels in myocardial tissue were then evaluated. Immunofluorescence and Western blotting analysis showed that odoratin reduced excess ROS, enhanced NO production and decreased fibrosis‐related protein expression in vitro. In vivo, odoratin significantly improved cardiac function, reduced ROS, increased NO levels and mitigated fibrosis in AAC‐induced mice. Both in vitro and in vivo, odoratin inhibited the expression of NADPH oxidase 4 and EZH2, while promoting the expression of phosphorylated endothelial nitric oxide synthase (p‐eNOS) and PPARγ. The anti‐fibrotic effects of odoratin were reversed by PPARγ antagonism, and EZH2 overexpression diminished PPARγ activation by odoratin. These findings suggest that odoratin may combat myocardial fibrosis by balancing ROS and NO through PPARγ activation, with EZH2 inhibition likely playing a key regulatory role. [ABSTRACT FROM AUTHOR]

Photoacoustic microscopy (PAM) utilizes short laser pulses to deposit energy into light absorbers and sensitively detects the ultrasonic waves the absorbers generate in response. PAM directly renders a three-dimensional spatial distribution of sub-surface optical absorbers. Unlike other optical imaging technologies, PAM features label-free optical absorption contrast and excellent imaging depths. Standard dental imaging instruments are limited to X-ray and CCD cameras. Subsurface optical dental imaging is difficult due to the highly-scattering enamel and dentin tissue. Thus, very few imaging methods can detect dental decay or diagnose dental pulp, which is the innermost part of the tooth, containing the nerves, blood vessels, and other cells. Here, we conducted a feasibility study on imaging dental decay and dental pulp with PAM. Our results showed that PAM is sensitive to the color change associated with dental decay. Although the relative PA signal distribution may be affected by surface contours and subsurface reflections from deeper dental tissue, monitoring changes in the PA signals (at the same site) over time is necessary to identify the progress of dental decay. Our results also showed that deep-imaging, near-infrared (NIR) PAM can sensitively image blood in the dental pulp of an in vitro tooth. In conclusion, PAM is a promising tool for imaging both dental decay and dental pulp. © 2011 SPIE.

PurposeTo obtain three-dimensional images from retinal transplants in live animals and evaluate the placement and structural quality of the transplants.MethodsDonor retinal sheets were isolated from E19 fetuses of transgenic rats expressing human alkaline phosphatase (hPAP), and transplanted to the subretinal space of 19-56 days old S334ter-3 rat recipients with fast retinal degeneration (average age at surgery 32 days). A total of 143 rats were imaged 1 day to 2.8 months after surgery, using a Fourier-domain optical coherence tomography (FDOCT) system, with an axial resolution of 3.5 microm. The CCD A-line integration time was set at 200 micros for better visualization of degenerated retina. After targeting the transplant area, 139 or 199 consecutive slices were scanned. Projection images and movies of the retinal transplant area were computed and later compared with histology.ResultsOCT scans identified 137 of 141 transplants as a thickening of the degenerated retina. OCT indicated the laminar structure of the transplants and surgical defects, such as RPE/choroid damage with an accuracy rate between 83 and 99%. Three-dimensional projections showed the transplant position in the retina in relation to the optic disc. Histology of transplants by hPAP and hematoxylin-eosin staining was correlated with the OCT results.ConclusionsOptical coherence tomography is an excellent tool to image retinal layers in a live rat. This procedure helps to evaluate the placement and quality of the transplants in the living eye.

Optical coherence tomography is an emerging non-invasive technology that provides high resolution, cross-sectional tomographic images of internal structures of specimens. It holds great potentials for a wide variety of applications, especially in the field of biomedical imaging. OCT images, however, are usually degraded by significant speckle noise. Here we report a 3D approach to attenuating speckle noise in OCT images. This approach is based on the 3D curvelet transform, and is conveniently controlled by a single parameter that determines the threshold in the curvelet domain. Unlike 2D approaches which only consider information in individual images, 3D processing, by analyzing all images in a volume simultaneously, has the advantage of also taking the information between images into account. This, coupled with the curvelet transform's nearly optimal sparse representation of curved edges that are common in OCT images, provides a simple yet powerful platform for speckle attenuation. We show the approach suppresses a significant amount of speckle noise, and in the mean time preserves and thus reveals many subtle features that could get attenuated in other approaches. © 2010 Copyright SPIE - The International Society for Optical Engineering.

We present a combined optical Doppler tomography/spectral Doppler imaging modality to quantitatively evaluate the dynamic blood circulation and the artery blockage before and after a localized ischemic stroke in a mouse model. Optical Doppler Tomography (ODT) combines the Doppler principle with optical coherence tomography for noninvasive localization and measurement of particle flow velocity in highly scattering media with micrometer scale spatial resolution. Spectral Doppler imaging (SDI) provides complementary temporal flow information to the spatially distributed flow information of Doppler imaging. Fast, repeated, ODT scans across an entire vessel were performed to record flow dynamic information with high temporal resolution of cardiac cycles. Spectral Doppler analysis of continuous Doppler images demonstrates how the velocity components and longitudinally projected flow-volume-rate change over time for scatters within the imaging volume using spectral Doppler waveforms. Furthermore, vascular conditions can be quantified with various Doppler-angle-independent flow indices. Non-invasive in-vivo mice experiments were performed to evaluate microvascular blood circulation of a localized ischemic stroke mouse model. © 2010 Copyright SPIE - The International Society for Optical Engineering.

Optical coherence tomography is an emerging non-invasive technology that provides high resolution, cross-sectional tomographic images of internal structures of specimens. OCT images, however, are usually degraded by significant speckle noise. Here we introduce to our knowledge the first 3D approach to attenuating speckle noise in OCT images. Unlike 2D approaches which only consider information in individual images, 3D processing, by analyzing all images in a volume simultaneously, has the advantage of also taking the information between images into account. This, coupled with the curvelet transform's nearly optimal sparse representation of curved edges that are common in OCT images, provides a simple yet powerful platform for speckle attenuation. We show the approach suppresses a significant amount of speckle noise, while in the mean time preserves and thus reveals many subtle features that could get attenuated in other approaches. (C) 2010 Optical Society of America

Phase microscopy for high-dynamic-range quantitative phase-contrast imaging of a transparent phase object was demonstrated. Using a common path Fourier domain optical coherence tomography system, this technique is capable of displacement measurement with a sensitivity of 34 pm. The limitation of 2pi ambiguity restriction was overcome by the use of a phase retrieval approach performed in spectral domain. Two-dimensional quantitative phase imaging of human neonatal dermal keratinocyte cells was demonstrated to evaluate the performance of the system for cell imaging.

We describe an algorithm based on shrinkage in the curvelet domain to attenuate speckles in optical coherence tomography (OCT) images. The algorithm exploits the curvelet transform's sparse representation of edge discontinuities that are common in OCT images and its ability to map signals and noise into different areas in the curvelet domain. The speckle attenuation is controlled by a single parameter that determines the threshold in the curvelet domain. Applying the algorithm to OCT images shows significant improvement of image quality.

Doppler Optical Coherence Tomography (DOCT) imaging of in-vivo retinal blood flow was widely studied as efforts of research community to push this technology into clinic. Spectral Doppler imaging of DOCT has been demonstrated as a quantification method of in-vivo pulsatile retinal blood flow in human eye. This technology has the all the advantages inherited from OCT comparing to Doppler ultrasound. Comparing to normal spatial-distributed color Doppler imaging of DOCT, spectral Doppler imaging can reveal more haemodynamics details on the time dimension. Although resistance index (RI) of a micro-vascular can be measured in vivo from human retina, the clinical significance of RI easurements still needs to be investigated. In vitro experiment conduced with ultrasound has demonstrated the higher vascular resistance value is associated with the higher RI measured assuming the constant compliance of vascular tube. In this study, the rodent window-chamber model (RWCM) was used as a platform to investigate the RI change as the micro-vasculature response to laser irradiation. The higher RI was measured after the occlusion of two veins (should it be arterials) that was verified with laser speckle imaging in our preliminary experiment results. © 2009 SPIE.

A functional Fourier domain optical coherence tomography instrument offering spectral Doppler imaging of in vivo pulsatile human retinal blood flow was constructed. An improved phase-resolved algorithm was developed to correct bulk motion artifacts. Spectral Doppler imaging provides complementary temporal flow information to the spatially distributed flow information of the color Doppler image by providing direct visualization of the Doppler spectrum of the flow whose pattern can be further quantified with various velocity envelope curves and their corresponding flow indices. The coefficient of repeatability on resistance index measurement was assessed by analyzing 14 measurements on two vessels within two normal subjects.

A series of antimony-bridged viologen derivatives, stiboviologens, were obtained by introducing an antimony atom into the viologen skeleton. By modifying them through N-alkylation and N-arylation, the optoelectronic properties of the stiboviologens were finely tuned. The stiboviologens displayed strong redox properties, high conjugation, and low energy gaps. Notably, the presence of the antimony atom significantly enhanced the ultrafast metal to ligand charge transfer (MLCT) process (to approximately 1 ps), as determined by femtosecond transient absorption studies. Leveraging their excellent optoelectronic properties, the stiboviologens were successfully applied in electrochromism and utilized as both photosensitizers and electron transfer agents for catalyzing α-amino C(sp3)–H functionalization reactions including the oxidative cyclization reaction and cross dehydrogenative coupling reaction under visible light conditions. These findings highlight the potential of stiboviologens as promising materials in the field of optoelectronics and their versatile utilization in synthetic transformations. [ABSTRACT FROM AUTHOR]

ObjectiveSutureless cataract surgery has been growing in popularity over the last decade. These clear corneal incisions allow for rapid visual recovery after phacoemulsification, but may be associated with an increased risk of endophthalmitis. The purpose of this study was to evaluate the effect of intraocular pressure (IOP), location, and angle of cataract incisions on wound apposition and sealing in postmortem globes.MethodsThis was an ex vivo laboratory investigation of 20 rabbit eyes and 14 human eyes. Self-sealing clear corneal, limbal, and scleral incisions were created and IOP was controlled with an infusion cannula. Incisions were made at a variety of angles. Optical coherence tomography was used to image the incisions in real time as the IOP was varied by raising and lowering the infusion bottle, so as to simulate the variation in IOP occurring with blinking or squeezing of the eye.ResultsWith each type of incision, optical coherence tomography demonstrated the dynamic nature of cataract wound morphology as IOP was varied. Higher IOPs, in general, were associated with more tightly sealed wounds than lower IOPs, but this varied according to the location and angle of the incisions. More perpendicular incisions, relative to the surface tangent, sealed less well than incisions created at smaller angles at higher levels of IOP; At lower IOPs, the reverse relationship was observed such that more perpendicular incisions sealed less well than smaller incision angles.ConclusionChanges in IOP may result in variable and sometime poor wound apposition in sutureless cataract incisions. The type of incision and angle of the incision may affect the likelihood of inoculation of the aqueous humor with potentially pathogenic bacteria. For each type of incision, there may be a critical angle at which the incision is better able to withstand fluctuations in IOP.

ObjectiveClear corneal cataract incisions without sutures allow for rapid visual rehabilitation after phacoemulsification but might be associated with an increased risk of postoperative infection. The goal of this study was to examine in vitro dynamic changes in unhealed clear corneal cataract incisions that might adversely affect the risk of intraocular infection.DesignLaboratory investigation.MethodsSelf-sealing clear corneal incisions were created in cadaveric human and rabbit eyes, and intraocular pressure was controlled with an infusion cannula. Incisions were imaged in real time using optical coherence tomography as intraocular pressure was varied. Using an artificial anterior chamber, India ink was applied to the surface of cadaveric human corneas with clear corneal incisions to detect possible flow of surface fluid along the incision. Intraocular pressure was varied by raising and lowering the infusion bottle so as to simulate the variation in intraocular pressure that would occur with successive blinks.ResultsOptical coherence tomography demonstrated variation of corneal wound morphology in response to changes in intraocular pressure. Higher intraocular pressures were associated with close apposition of the wound edges, with no tendency for wound leakage. At low intraocular pressures, however, wound edges tended to gape, starting at the internal aspect of the wound. One incision opened along the entire length, allowing fluid flow across the cornea. Histologic examination revealed India ink particles in all incisions for up to three fourths of the length of the wound.ConclusionsTransient reduction of intraocular pressure might result in poor wound apposition in clear corneal incisions, with the potential for fluid flow across the cornea and into the anterior chamber, with the attendant risk of endophthalmitis.

The reactions of cyclic (alkyl)(amino)germylenes (CAAGe) with copper(I) and gold(I) complexes were investigated. CAAGe (1) reacts with CuBr(SMe2) leading to a tetrameric germylene complex [CAAGeCuBr]4 (2), whereas CAAGe (3) undergoes Au−Cl bond insertion with LAuCl (L=phosphine or N‐heterocyclic carbene) to afford germanium gold(I) complexes (5 and 6). Chlorine abstraction of 6 gives the cationic germylene gold(I) complex 7. [ABSTRACT FROM AUTHOR]