ABSTRACT
Since the conventional coherent transceiver is costly to be deployed in short-reach networks due to its complicated receiver structure, it is desired to simplify the structure itself. In this paper, we propose a simple polarization-diversity coherent receiver structure by exploiting the concept of the Stokes analyzer. Compared to the conventional architecture, the number of the photodiodes (PDs) is reduced from eight to six without relying on complicated analog circuits. In addition, splitters and combiners for dual-polarization (DP) signals can be replaced with only one polarization beam splitter or combiner (PBS/C). For evaluation of the proof-of-concept (PoC), we developed a prototype of the receiver using free-space optical components. We demonstrate the transmission of 120-Gb/s DP quadrature phase-shift keying (QPSK) and DP 8-ary quadrature-amplitude modulation (8QAM) signals over a 100-km single-mode fiber (SMF). We believe that the demonstrated architecture could potentially be integrated monolithically on silicon-photonic or InP platforms to realize compact and low-cost coherent transceivers for short-reach applications.
ABSTRACT
To determine if a prediction of epidemic cholera using climate data can be made, we performed autoregression analysis using the data recorded in Dhaka City, Bangladesh over a 20-year period (1983-2002) comparing the number of children aged <10 years who were infected with Vibrio cholerae O1 to the maximum and minimum temperatures and rainfall. We formulated a simple autoregression model that predicts the monthly number of patients using earlier climate variables. The monthly number of patients predicted by this model agreed well with the actual monthly number of patients where the Pearson's correlation coefficient was 0.95. Arbitrarily defined, 39.4% of the predicted numbers during the study period were within 0.8-1.2 times the observed numbers. This prediction model uses the climate data recorded 2-4 months before. Therefore, our approach may be a good basis for establishing a practical early warning system for epidemic cholera.
Subject(s)
Cholera/epidemiology , Cholera/prevention & control , Disease Outbreaks , Models, Statistical , Vibrio cholerae O1 , Bangladesh/epidemiology , Child , Child, Preschool , Cholera/etiology , Cholera/pathology , Climate , Humans , Infant , Infant, Newborn , Predictive Value of Tests , Rain , Regression Analysis , TemperatureABSTRACT
3 beta,16 beta,19-Trihydroxyandrost-5-en-17-one (12) was synthesized from 5 alpha-bromo-3 beta-acetoxy-6 beta,19-epoxyandrostan-17-one (2) through acetoxylation at C-16 beta of the enol acetate 4 with lead tetraacetate and reductive cleavage of the epoxide ring with zinc dust yielding the 3 beta,16 beta-diacetoxy-19-hydroxy steroid 11, followed by hydrolysis of the acetoxy groups with sulfuric acid. Jones oxidation of compound 11 followed by the acid hydrolysis gave the 19-oxo steroid 15. 5 alpha-Bromo-3 beta-hydroxy-16 beta-acetoxy-6 beta,19-epoxyandrostan-17-one (8), obtained by selective hydrolysis of the 3-formate 5 with ammonium hydroxide, was oxidized with Jones reagent to afford the 3-oxo steroid 16, which was converted into the 19-hydroxy derivative 17 by treatment with zinc dust. 16 beta,19-Dihydroxyandrost-4-ene-3,17-dione (18) and its 19-oxo derivative 21 were obtained from compound 17 through a similar reaction sequence.