polarization

摘要： Triggering receptor expressed on myeloid cells-like 2(TREML2)is a newly identified susceptibility gene for Alzheimer's disease(AD).It encodes a microglial inflammation-associated receptor.To date,the potential role of mic roglial TREML2 in neuroinflammation in the context of AD remains unclear.In this study,APP/PS1 mice were used to investigate the dynamic changes of TREML2 levels in brain during AD progression.In addition,lipopolysaccharide(LPS)stimulation of primary microglia as well as a lentivirus-mediated TREML2 overexpression and knockdown were employed to explore the role of TREML2 in neuroinflammation in the context of AD.Our res ults show that TREML2 levels gradually increased in the brains of AP P/PS1 mice during disease progression.LPS stimulation of primary microglia led to the release of inflammato ry cytokines including interleukin-1β,inte rleukin-6,and tumor necrosis factor-a in the culture medium.The LPS-induced mic roglial release of inflammatory cytokines was enhanced by TREML2 overexpression and was attenuated by TREML2 knoc kdown.LPS increased the levels of mic roglial M1-type polarization marker inducible nitric oxide synthase.This effect was enhanced by TREML2 overexpression and ameliorated by TREML2 knockdown.Furthermore,the levels of microglial M2-type polarization markers CD206 and ARG1 in the primary microglia were reduced by TREML2 overexpression and elevated by TREML2 knockdown.LPS stimulation increased the levels of NLRP3 in primary microglia.The LPS-induced increase in NLRP3 was further elevated by TREML2 overexpression and alleviated by TREML2 knockdown.In summary,this study provides the first evidence that TREML2 modulates inflammation by regulating microglial polarization and NLRP3 inflammasome activation.These findings reveal the mechanisms by which TREML2 regulates microglial inflammation and suggest that TREML2 inhibition may represent a novel therapeutic strategy for AD.

摘要： Metasurfaces that can realize the polarization manipulation of electromagnetic waves on the sub-wavelength scale have become an emerging research field.Here,a novel strategy of combining the metasurface and Fresnel zone plate to form a metasurface zone plate is proposed to realize the conversion from nearly arbitrary polarizations to a fixed polarization.Specifically,when one polarized wave is incident on adjacent ring zones constructed by different types of meta-atoms,the transmitted waves generated by odd-numbered and even-numbered ring zones converge at the same focus and superimpose to generate a fixed polarized wave.As function demonstrations,we have designed two types of metasurface zone plates:one is a focused linear polarizer,and the other can convert nearly arbitrary polarized waves into focused circularly polarized waves.The simulated and measured results are consistent with theoretical expectations,suggesting that the proposed concept is flexible and feasible.Our work provides an alternative platform for polarization manipulation and may vigorously promote the development of polarization photonic devices.

摘要： Pathologic inflammatory conditions are frequently correlated with dynamic alterations through macrophage activation,with classically activated Ml cells associated with promoting and sustaining inflammation and M2 cells implicated in resolving or smoldering chronic inflammation.Inflammation is a common feature of various chronic diseases,and it has direct involvement in the emergence and progression of these conditions.Macrophages participate in an autoregulatory loop characterizing inflammatory process,as they produce a wide range of biologically active mediators that exert either deleterious or beneficial effects during inflammation.Therefore,balancing the ratio of M1/M2 macrophages can help to ameliorate the inflammatory landscape of pathological conditions.This review will explore the role of macrophage polarization in distant pathological inflammatory conditions,such as cancer,autoimmunity,renal inflammation,stroke,and atherosclerosis,while sharing macrophage-driven pathogenesis.

摘要： Obtaining polarization information enables researchers to enhance underwater imaging quality by removing backscattering effect and to distinguish targets of different materials.However,due to the simplified assumption of unpolarized target light,most of the existing underwater polari-metric methods lose part of the polarization information,resulting in degraded imaging quality.In this work,a novel underwater polarimetric method is reported,which obtains the angle of polariza-tion(AOP)map to improve imaging quality.Specifically,the Stokes vectors were exploited to re-move the backscattering effect by obtaining two pairs of orthogonal polarization sub-images of the underwater scene.The target reflected light and the angle between the polarization directions of the target reflected light and the backscattered light were computed through the two groups of the or-thogonal polarized sub-images.The AOP map of the target light could be derived from the Stokes vectors.Then,the transmission map of the target light was estimated by using the non-local color priorly combined with the properties of light propagating underwater.Experiments show that the reported technique enables distinguishing different targets when the colors are similar.The quantit-ative metrics validate that the reported technique produces state-of-the-art performance for under-water imaging.

摘要： In this work,we study the magnetic field morphology of selected star-forming clouds spread over the galactic latitude(b)range−10°to 10°.The polarimetric observations of clouds CB24,CB27 and CB188 are conducted to study the magnetic field geometry of those clouds using the 104 cm Sampurnanand Telescope(ST)located at ARIES,Manora Peak,Nainital,India.These observations are combined with those of 14 further low latitude clouds available in the literature.Most of these clouds are located within a distance range 140–500 pc except for CB3(∼2500 pc),CB34(∼1500 pc),CB39(∼1500 pc)and CB60(∼1500 pc).Analyzing the polarimetric data of 17 clouds,we find that the alignment between the envelope magnetic field(θ^(env)_(B))and galactic plane(GP)(θGP)of the low-latitude clouds varies with their galactic longitudes(l).We observe a strong correlation between the longitude(l)and the offset(θ_(off)=|θ^(env)_(B)-θ_(GP))which shows that θ^(env)_(B) is parallel to the GP when the clouds are situated in the region 115°250°.To check the consistency of our results,the stellar polarization data available in the Heiles catalog are overlaid on the DSS image of the clouds having mean polarization vector of field stars.The results are almost consistent with the Heiles data.A systematic discussion is presented in the paper.The effect of turbulence in the cloud is also studied which may play an important role in causing the misalignment phenomenon observed between θ^(env)_(B) and θ_(GP).We have used Herschel(Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.)SPIRE 500μm and SCUBA 850μm dust continuum emission maps in our work to understand the density structure of the clouds.

摘要： PSR B1237+25,whose mean pulse profile has five components,is a well-known star to study pulsar emission geometries.We conducted mode changing and modulation analysis on this pulsar using FAST data at 1.25 GHz with a bandwidth of 400 MHz.We observed and identified three emission modes of this pulsar:a quiet normal mode that has little or no core activity with distinctive 2.8-period subpulse modulation on its outer cone,a flare normal mode in which the core is highly active and an abnormal mode in which the core is active and the last component is weak.We found that the core activity cuts off the position angle traverse in flare normal mode and leads to a position angle jumping in abnormal mode.We also found that there exists a quasi-periodical modulation on the outer conal components.Such modulation shows an irregular wave-like pattern,and has a weak correlation with the core component.We discuss the likely origin of such a modulation,and argue that this modulation can be interpreted as precession of the emission cones around the magnetic axis.

摘要： This article presents a Sub-6 GHz microstrip patch antenna(MPA)with enhanced gain using metamaterial(MTM)superstrate.The source MPA operates at 4.8 GHz and has a peak gain of 5.3 dBi at the resonance frequency.A window-shaped unit cell is designed and investigated through the material wave propagation technique.The unit cell shows an EpsilonNear Zero(ENZ)-Mu Very Large(MVL)behavior around 4.8 GHz.The unit cell has a fourfold geometry which makes it a polarization independent metamaterial.A double layer antenna is designed by placing a 4×4 MTM slab as a superstrate above the MPA at a height of 0.208λ0;whereλ0 is the free-space wavelength at the resonance frequency of the antenna.Impedance matching and gain of the source antenna is improved using the metamaterial.The simulation as well as measurement results show that novel antenna system has a peak gain of 7.68 dBi at 4.8 GHz and an impedance bandwidth of 0.22 GHz.The overall dimension of the antenna is 75×60×15 mm^(3).The proposed antenna operates in the Sub-6 GHz band and is suitable for 5G applications.

摘要： The curvature radiation is applied to the explanation of the circular polarization of fast radio bursts(FRBs).Significant circular polarization is reported in both apparently non-repeating and repeating FRBs.Curvature radiation can produce significant circular polarization at the wing of the radiation beam.In the curvature radiation scenario,in order to see significant circular polarization in FRBs,(1) more energetic bursts,(2) bursts with electrons having higher Lorentz factor,and(3) a slowly rotating neutron star at the center are required.Different rotational period of the central neutron star may explain why some FRBs have high circular polarization,while others do not.Considering possible difference in refractive index for the parallel and perpendicular components of electric field,the position angle may change rapidly over the narrow pulse window of the radiation beam.The position angle swing in FRBs may also be explained by this non-geometric origin,besides that of the rotating vector model.

摘要： A low-profile ultra-wideband(UWB)band-stop frequency selective surface(FSS)is designed for S-,C-,X-and Ku-bands communication applications.The FSS is constructed by using square and circular loop elements printed on the top and bottom sides of the RO3210 substrate.The FSS has been designed to reduce the electromagnetic interference(EMI)as well as to mitigate the harmful effects of electromagnetic radiation on the human body caused by different radio devices.The dimension and size of the UWB FSS have been reduced to 0.12λ×0.12λand 90%,respectively,as compared to the reported literature.The other advantages of the proposed FSS are that it is low profile,it has a simplified geometry and it ensures better angular and polarization stability of up to 85◦.The-10 and-20 dB bandwidths of the proposed FSS are 146%(2.0-13.0 GHz)and 80%(4.87-11.42 GHz),respectively.Theoretical results have been obtained using ANSYS HFSS and verified through measured results.

摘要： Because of their ability to sustain extremely high-amplitude electromagnetic fields and transient density and field profiles,plasma optical components are being developed to amplify,compress,and condition high-power laser pulses.We recently demonstrated the potential to use a relativistic plasma aperture—produced during the interaction of a high-power laser pulse with an ultrathin foil target—to tailor the spatiotemporal properties of the intense fundamental and second-harmonic light generated[Duff et al.,Sci.Rep.10,105(2020)].Herein,we explore numerically the interaction of an intense laser pulse with a preformed aperture target to generate second-harmonic laser light with higher-order spatial modes.The maximum generation efficiency is found for an aperture diameter close to the full width at half maximum of the laser focus and for a micrometer-scale target thickness.The spatial mode generated is shown to depend strongly on the polarization of the drive laser pulse,which enables changing between a linearly polarized TEM01 mode and a circularly polarized Laguerre–Gaussian LG01 mode.This demonstrates the use of a plasma aperture to generate intense higher-frequency light with selectable spatial mode structure.

摘要： The polarizations of dielectronic recombination satellite lines for hydrogenlike F to U ions are calculated including the generalized Breit interaction(GBI). The calculated values of the asymmetry parameter are compared with other theoretical results and good agreements are obtained for all lines except for those from the level 2s2p3P, .The GBI effects on the polarization become much stronger as the atomic number increases. However, for different lines the GBI effects on the polarization are different.