N-Morpholino-Δ8-dihydro­abietamide

The title compound, C24H39NO2 (systematic name: 4-{[1,4a-dimethyl-7-(propan-2-yl)-1,2,3,4,4a,5,6,7,8,9,10,10a-dodeca­hydro­phenanthren-1-yl]carbon­yl}morpholine), has been synthesized from Δ8-dihydro­abietic acid. Two cyclo­hexene rings adopt half-chair conformations, whereas the cyclo­hexane and morpholine rings are each in the chair conformation. Two methyl groups are in an axial position with respect to the tricyclic hydro­phenanthrene nuclei

Spatiotemporal Sparse Bayesian Learning with Applications to Compressed Sensing of Multichannel Physiological Signals

Energy consumption is an important issue in continuous wireless telemonitoring of physiological signals. Compressed sensing (CS) is a promising framework to address it, due to its energy-efficient data compression procedure. However, most CS algorithms have difficulty in data recovery due to non-sparsity characteristic of many physiological signals. Block sparse Bayesian learning (BSBL) is an effective approach to recover such signals with satisfactory recovery quality. However, it is time-consuming in recovering multichannel signals, since its computational load almost linearly increases with the number of channels. This work proposes a spatiotemporal sparse Bayesian learning algorithm to recover multichannel signals simultaneously. It not only exploits temporal correlation within each channel signal, but also exploits inter-channel correlation among different channel signals. Furthermore, its computational load is not significantly affected by the number of channels. The proposed algorithm was applied to brain computer interface (BCI) and EEG-based driver's drowsiness estimation. Results showed that the algorithm had both better recovery performance and much higher speed than BSBL. Particularly, the proposed algorithm ensured that the BCI classification and the drowsiness estimation had little degradation even when data were compressed by 80%, making it very suitable for continuous wireless telemonitoring of multichannel signals.Comment: Codes are available at: https://sites.google.com/site/researchbyzhang/stsb

The magnetic field in the NGC 2024 FIR 5 dense core

We used the Submillimeter Array (SMA) to observe the thermal polarized dust emission from the protostellar source NGC 2024 FIR 5. The polarized emission outlines a partial hourglass morphology for the plane-of-sky component of the core magnetic field. Our data are consistent with previous BIMA maps, and the overall magnetic field geometries obtained with both instruments are similar. We resolve the main core into two components, FIR 5A and FIR 5B. A possible explanation for the asymmetrical field lies in depolarization effects due to the lack of internal heating from FIR 5B source, which may be in a prestellar evolutionary state. The field strength was estimated to be 2.2 mG, in agreement with previous BIMA data. We discuss the influence of a nearby H{\sc ii} region over the field lines at scales of $\sim 0.01$ pc. Although the hot component is probably compressing the molecular gas where the dust core is embedded, it is unlikely that the radiation pressure exceeds the magnetic tension. Finally, a complex outflow morphology is observed in CO (3 $\rightarrow$ 2) maps. Unlike previous maps, several features associated with dust condensations other than FIR 5 are detected.Comment: 48 pages, 12 figures, accepted for publication in The Astrophysical Journa

Detection of 40-48 GHz dust continuum linear polarization towards the Class 0 young stellar object IRAS 16293-2422

We performed the new JVLA full polarization observations at 40-48 GHz (6.3-7.5 mm) towards the nearby ($d$ $=$147$\pm$3.4 pc) Class 0 YSO IRAS 16293-2422, and compare with the previous SMA observations reported by Rao et al. (2009; 2014). We observed the quasar J1407+2827 which is weakly polarized and can be used as a leakage term calibrator for $<$9 GHz observations, to gauge the potential residual polarization leakage after calibration. We did not detect Stokes Q, U, and V intensities from the observations of J1407+2827, and constrain (3-$\sigma$) the residual polarization leakage after calibration to be $\lesssim$0.3\%. We detect linear polarization from one of the two binary components of our target source, IRAS\,16293-2422\,B. The derived polarization position angles from our observations are in excellent agreement with those detected from the previous observations of the SMA, implying that on the spatial scale we are probing ($\sim$50-1000 au), the physical mechanisms for polarizing the continuum emission do not vary significantly over the wavelength range of $\sim$0.88-7.5 mm. We hypothesize that the observed polarization position angles trace the magnetic field which converges from large scale to an approximately face-on rotating accretion flow. In this scenario, magnetic field is predominantly poloidal on $>$100 au scales, and becomes toroidal on smaller scales. However, this interpretation remains uncertain due to the high dust optical depths at the central region of IRAS\,16293-2422\,B and the uncertain temperature profile. We suggest that dust polarization at wavelengths comparable or longer than 7\,mm may still trace interstellar magnetic field. Future sensitive observations of dust polarization in the fully optically thin regime will have paramount importance for unambiguously resolving the magnetic field configuration.Comment: 14 pages, 7 figures, accepted to A&A. Comments are welcom

N-Benzyl­idenenordehydro­abietylamine

The title compound [systematic name: (1R,4aS,10aR,E)-N-benzyl­idene-7-isopropyl-1,4a-dimethyl-1,2,3,4,4a,9,10,10a-octa­hydro­phenanthren-1-amine], C26H33N, has been synthesized from nor-dehydro­abietylamine and benzaldehyde. The two cyclo­hexane rings form a trans ring junction with classic chair and half-chair conformations, respectively, the two methyl groups are on the same side of tricyclic hydro­phenanthrene structure. The dihedral angle between two benzene rings is 44.2 (4)°. The C=N bond is in an E configuration

N-(2-Pyridylmethyleneamino)dehydro­abietylamine

The title compound {systematic name: 1-[(1R,4aS,10aR)-7-isopropyl-1,2,3,4,4a,9,10,10a-octa­hydro­phenanthren-1-yl]-N-[(E)-2-pyridylmethyleneamino]methanamine}, C26H33N2, has been synthesized from dehydro­abietylamine. The two cyclo­hexane rings form a trans ring junction with classic chair and half-chair conformations, respectively, whereas the benzene and pyridine rings are almost planar, and the dihedral angle between them is 80.4°. The two methyl groups directly attached to the tricyclic nucleus are on the same side of the tricyclic hydro­phenanthrene structure