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Imaging polarimetry in the LWIR with microgrid polarimeters  [cached]
Tyo J.S.
EPJ Web of Conferences , 2010, DOI: 10.1051/epjconf/20100504009
Abstract: Microgrid polarimeters have emerged over the past decade as a viable tool for performing real-time, highly accurate polarimetric imagery. A microgrid polarimeter operates by integrating a focal plane array (FPA) with an array of micropolarizing optics. Mircrogrids have the advantage of being relatively compact, rugged, and inherently spatiotemporally aligned. However, they have the single disadvantage that the various polarization measurements that go into estimating the Stokes parameters at a particular pixel are actually coming from separate locations in the field. Hence, a microgrid polarimeter performs best where there is no image information, obviating the need for an imaging polarimeter! Recently we have been working with a LWIR microgrid polarimeter at the College of Optical Sciences. Our instrument is a DRS Sensors & Targeting Systems 640 x 480 HgCdTe FPA with linear polarizers at 0°, 45°, 90°, and 135° [1]. In this paper we will review our recent results that derive methods for artifact-free reconstruction of band limited imagery.
环孔工艺的碲镉汞长波红外576×6焦平面探测器组件  [PDF]
红外与毫米波学报 , 2008,
Abstract: 碲镉汞长波红外576×6焦平面探测器组件是高性能热像仪的核心组件.本文中作者完成了碲镉汞长波红外576×6焦平面探测器组件的设计,利用环孔技术制备出576×6焦平面探测器芯片,经过杜瓦封装、配斯特林制冷机后成为实用的探测器组件.性能参数测试表明:典型的探测率达到1.79×1011cmHz1/2/W,非均匀性达到14.6%,盲元率达到6.0%,并完成探测器组件的实验室演示成像.
红外与毫米波学报 , 2008,
Abstract: 碲镉汞长波红外576×6焦平面探测器组件是高性能热像仪的核心组件.本文中作者完成了碲镉汞长波红外576×6焦平面探测器组件的设计,利用环孔技术制备出576×6焦平面探测器芯片,经过杜瓦封装、配斯特林制冷机后成为实用的探测器组件.性能参数测试表明:典型的探测率达到1.79×10^11cmHz^1/2/w,非均匀性达到14.6%,盲元率达到6.0%,并完成探测器组件的实验室演示成像.
Plasmonic Band-Pass Microfilters for LWIR Absorption Spectroscopy  [PDF]
J. M. Banks,P. D. Flammer,T. E. Furtak,R. E. Hollingsworth,R. T. Collins
International Journal of Optics , 2012, DOI: 10.1155/2012/916482
Abstract: Absorption spectroscopy in the long wave infrared provides an effective method for identification of various hazardous chemicals. We present a theoretical design for plasmonic band-pass filters that can be used to provide wavelength selectivity for uncooled microbolometer sensors. The microfilters consist of a pair of input reflection gratings that couple light into a plasmonic waveguide with a central resonant waveguide cavity. An output transmission grating on the other side of the structure pulls light out of the waveguide where it is detected by a closely spaced sensor. Fabrication of the filters can be performed using standard photolithography procedures. A spectral bandpass with a full-width at half-maximum (FWHM) of 100?nm can be obtained with a center wavelength spanning the entire 8–12?μm atmospheric transmission window by simple geometric scaling of only the lateral dimensions. This allows the simultaneous fabrication of all the wavelength filters needed for a full spectrometer on a chip. 1. Introduction Detection of long-wave infrared (LWIR) light in the 8–12?μm atmospheric transmission band is an important area of research with a high demand for good wavelength resolution, high sensitivity, portability, and affordability. An important application for LWIR detection is absorption spectroscopy for remote sensing of chemical vapors [1]. There have been several approaches for spectral imaging of LWIR light. One approach is to rapidly tune a liquid crystal-filled Fabry-Perot etalon coupled with a cooled LWIR camera to detect light over a wide wavelength range with good spectral resolution [2]. Cryogenic cooling, however, greatly increases the cost of operation and portability of the detector. Uncooled microbolometer sensors are commonly used as an alternative to the cooled detectors for thermal imaging, but they show low sensitivity [3]. It has been shown in recent work [4] that uncooled microbolometers, absorbing only a narrow band of radiation, can have sensitivities approaching that of cooled detectors. There are several ways to narrow the band of absorbed light in a microbolometer detector, including antennas [5–7], metamaterials [8–11], and vertical optical cavities [4, 12–17]. Vertical Fabry-Perot cavities are especially convenient to use since they can be placed above conventional microbolometer arrays. However, this requires the vertical dimensions to be changed for the detection of different wavelengths. The most common way this is achieved is by tuning the resonant wavelength by moving one of the mirrors via an included
Transcription Termination and Chimeric RNA Formation Controlled by Arabidopsis thaliana FPA  [PDF]
Céline Duc,Alexander Sherstnev,Christian Cole,Geoffrey J. Barton ,Gordon G. Simpson
PLOS Genetics , 2013, DOI: 10.1371/journal.pgen.1003867
Abstract: Alternative cleavage and polyadenylation influence the coding and regulatory potential of mRNAs and where transcription termination occurs. Although widespread, few regulators of this process are known. The Arabidopsis thaliana protein FPA is a rare example of a trans-acting regulator of poly(A) site choice. Analysing fpa mutants therefore provides an opportunity to reveal generic consequences of disrupting this process. We used direct RNA sequencing to quantify shifts in RNA 3′ formation in fpa mutants. Here we show that specific chimeric RNAs formed between the exons of otherwise separate genes are a striking consequence of loss of FPA function. We define intergenic read-through transcripts resulting from defective RNA 3′ end formation in fpa mutants and detail cryptic splicing and antisense transcription associated with these read-through RNAs. We identify alternative polyadenylation within introns that is sensitive to FPA and show FPA-dependent shifts in IBM1 poly(A) site selection that differ from those recently defined in mutants defective in intragenic heterochromatin and DNA methylation. Finally, we show that defective termination at specific loci in fpa mutants is shared with dicer-like 1 (dcl1) or dcl4 mutants, leading us to develop alternative explanations for some silencing roles of these proteins. We relate our findings to the impact that altered patterns of 3′ end formation can have on gene and genome organisation.

HU Xu,TAI Yun-Jian,YUAN Jun,CAI Yi,

红外与毫米波学报 , 2006,
Abstract: Progress in Hybrid Uncooled Pyroelectric IR FPA was introduced. Not only the electric and physical characteristics of the materials that are used in the FPA,but also its heat isolation structure and ROIC technology were discussed in datail.The key factor of the FPA's performance was analyzed.At last,the experimental result and some methods were discussed and analyzed.
Latest Development of Hybrid Uncooled Pyroelectric IR FPA

Hu Xu,Tai Yunjian,Huang Chengcai,Cai Yi,

光子学报 , 2005,
Abstract: 128×128 element Hybrid Uncooled Pyroelectric IR FPA,which was developed by Kunming Institute of Physics,was introduced in this paper.First,the national and oversea development of Hybrid Uncooled Pyroelectric IR FPA and hybrid structure was used in the FPA were presented,then the key factor that effected on the FPA′s performance was analyzed.Not only were the material′s electrics and physical characteristic that were applied in the FPA,but also heat isolation structure and ROIC technology were discussed.Some IR explicit picture getting from the IR FPA was given.At last,experimentation result and some methods that improving performance was applied in the future were discussed and analyzed.
基于光学读出非制冷红外成像系统的无基底FPA等效电学模型  [PDF]
红外与毫米波学报 , 2013,
Abstract: 与传统的有基底FPA(焦平面阵列)相比,基于全镂空支撑框架结构的新型无基底FPA在热学特性上存在显著差异,传统的基于恒温基底假设的热学分析模型不再适用,因此,通过电学比拟方法,将无基底FPA的热响应特性等效为电学模型.通过该模型,进一步分析了无基底FPA在非真空环境下的热学性能,分析表明:该无基底FPA具有在大气压下优良的红外成像性能,其NETD(噪声等效温度差)值仅比真空环境下增加了数倍.
The Infall Region of Abell 576: Independent Mass and Light Profiles  [PDF]
K. Rines,M. J. Geller,A. Diaferio,J. J. Mohr,G. A. Wegner
Physics , 2000, DOI: 10.1086/316811
Abstract: We describe observations of the nearby cluster of galaxies A576 beyond the virial radius and into the infall region. Using 1057 redshifts, we use the infall pattern in redshift space to determine the mass profile of A576 to a radius of ~4 Mpc/h. This mass estimation technique makes no assumptions about the equilibrium state of the cluster. Within 1 Mpc/h, the mass profile we derive exceeds that determined from X-ray observations by a factor of 2.5. At \~2.5 Mpc/h, however, the mass profile agrees with virial mass estimates. Our mass profile is consistent with a NFW or Hernquist profile, but it is inconsistent with an isothermal sphere. R-band images of a $3^\circ x 3^\circ$ region centered on the cluster allow an independent determination of the cluster light profile. We calculate the integrated mass-to-light ratio as a function of cluster radius; it decreases smoothly from the core to ~4 Mpc/h. The differential dM/dL_R profile decreases more steeply; we find M/L_R ~100 h at ~4 Mpc/h, in good agreement with the mass-to-light ratios of individual galaxies. This value implies $\Omega_m \lesssim 0.4$ at 95% confidence. For a Hernquist model, the best-fit mass profiles differ from the observed surface number density of galaxies; the galaxies have a larger scale radius than the mass. This result is consistent with the centrally peaked $M/L_R$ profile. Similarly, the scale radius of the light profile is larger than that of the mass profile. We discuss some potential systematic effects; none can easily reconcile our results with a constant mass-to-light ratio. (abstract edited)
A Novel TetR Family Transcriptional Regulator, SAV576, Negatively Controls Avermectin Biosynthesis in Streptomyces avermitilis  [PDF]
Jia Guo, Xuan Zhang, Shuai Luo, Fei He, Zhi Chen, Ying Wen, Jilun Li
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0071330
Abstract: Avermectins produced by Streptomyces avermitilis are potent anti-parasitic agents that are useful in animal health care, agriculture, and the treatment of human infections. In a search for novel regulators that affect avermectin biosynthesis, comparative transcriptome analysis was performed between wild-type strain ATCC31267 and avermectin overproducing strain 76-02-e, revealing some differentially expressed genes. SAV576, which is downregulated in 76-02-e and encodes a TetR family transcriptional regulator (TFR), was shown to inhibit avermectin production by indirectly affecting the expression of ave genes. SAV576 directly repressed the transcription of its gene SAV576 and of adjacent genes SAV575 (encodes cytochrome P450/NADPH-ferrihemoprotein reductase) and SAV574. The SAV576-binding sites within the bidirectional SAV575-SAV576 promoter region were determined by DNase I footprinting assays. A consensus 15-bp palindromic sequence CCRTACRVYGTATGS was found in these binding sites and shown to be important for SAV576-binding activity. SAV575, an important target gene of SAV576, was shown to exert a positive effect on avermectin production. The study findings extend our limited knowledge of the complex regulation of avermectin biosynthesis and provide a basis for rational genetic manipulation of S. avermitilis to improve avermectin production through control of SAV576 and its target gene.
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