Detection and mitigation of radio frequency interference （RFI） is the first and also the key step for data processing in radio observations, especially for ongoing low frequency radio experiments towards the detecti...Detection and mitigation of radio frequency interference （RFI） is the first and also the key step for data processing in radio observations, especially for ongoing low frequency radio experiments towards the detection of the cosmic dawn and epoch of reionization （EoR）. In this paper we demonstrate the tech- nique and efficiency of RFI identification and mitigation for the 21 Centimeter Array （21CMA）, a radio interferometer dedicated to the statistical measurement of EoR. For terrestrial, man-made RFI, we concen- trate mainly on a statistical approach by identifying and then excising non-Gaussian signatures, in the sense that the extremely weak cosmic signal is actually buried under thermal and therefore Gaussian noise. We also introduce the so-called visibility correlation coefficient instead of conventional visibility, which allows a further suppression of rapidly time-varying RFI. Finally, we briefly discuss removals of the sky RFI, the leakage of sidelobes from off-field strong radio sources with time-invariant power and a featureless spec- trum. It turns out that state of the art technique should allow us to detect and mitigate RFI to a satisfactory level in present low frequency interferometer observations such as those acquired with the 21CMA, and the accuracy and efficiency can be greatly improved with the employment of low-cost, high-speed computing facilities for data acquisition and processing.展开更多
INTRODUCTION Fatal familial insomnia （FFI） is a serious and rare prion disease, which was first reported by Lugaresi et al. in 1986.Early diagnosis of FFI might be important for early and sufficient counseling of pa...INTRODUCTION Fatal familial insomnia （FFI） is a serious and rare prion disease, which was first reported by Lugaresi et al. in 1986.Early diagnosis of FFI might be important for early and sufficient counseling of patients and their relatives, also concerning the risk of inheritance, and potentially also for treatment studies. However, the diagnosis of FFI might be difficult because of the heterogeneity of clinical features, low sensitivity of diagnostic tests, and absence of family history. The aim of the present study was to develop a clinical scheme and diagnostic criteria for FFI based on our research and expert consensus.展开更多
基金partially supported by the National Natural Science Foundation of China(Grant No.11433002)support by a Marsden Fund grant in New Zealand
文摘Detection and mitigation of radio frequency interference （RFI） is the first and also the key step for data processing in radio observations, especially for ongoing low frequency radio experiments towards the detection of the cosmic dawn and epoch of reionization （EoR）. In this paper we demonstrate the tech- nique and efficiency of RFI identification and mitigation for the 21 Centimeter Array （21CMA）, a radio interferometer dedicated to the statistical measurement of EoR. For terrestrial, man-made RFI, we concen- trate mainly on a statistical approach by identifying and then excising non-Gaussian signatures, in the sense that the extremely weak cosmic signal is actually buried under thermal and therefore Gaussian noise. We also introduce the so-called visibility correlation coefficient instead of conventional visibility, which allows a further suppression of rapidly time-varying RFI. Finally, we briefly discuss removals of the sky RFI, the leakage of sidelobes from off-field strong radio sources with time-invariant power and a featureless spec- trum. It turns out that state of the art technique should allow us to detect and mitigate RFI to a satisfactory level in present low frequency interferometer observations such as those acquired with the 21CMA, and the accuracy and efficiency can be greatly improved with the employment of low-cost, high-speed computing facilities for data acquisition and processing.
基金This work was supported by grants from the National Natural Science Foundation of China （No. 81470074）, and the Clinical funding from Beijing Municipal Science and Technology Committee （No.Z141107002514117）.
文摘INTRODUCTION Fatal familial insomnia （FFI） is a serious and rare prion disease, which was first reported by Lugaresi et al. in 1986.Early diagnosis of FFI might be important for early and sufficient counseling of patients and their relatives, also concerning the risk of inheritance, and potentially also for treatment studies. However, the diagnosis of FFI might be difficult because of the heterogeneity of clinical features, low sensitivity of diagnostic tests, and absence of family history. The aim of the present study was to develop a clinical scheme and diagnostic criteria for FFI based on our research and expert consensus.
