ALBERT

Description: We performed a 22 GHz H 2 O maser survey towards 221 Bolocam Galactic Plane Survey (BGPS) sources. We detected 107 H 2 O masers, of which 12 are new. The detection rate is 48.4 per cent for our sample. We obtained the positions of five new H 2 O masers via On The Fly (OTF) observations. The detection rate of H 2 O masers is correlated with continuum emission fluxes of BGPS sources at far-infrared, sub-millimetre and millimetre wavelengths. We employed the classification of Dunham et al. to classify the evolutionary stage of BGPS sources into Group 0, 1, 2, and 3. The detection rate and velocity range of H 2 O masers increases as the BGPS sources evolve from Group 1 to Group 3. The BGPS sources associated with both H 2 O and CH 3 OH masers are more compact than that associated with either only H 2 O or only CH 3 OH masers. This indicates that the sources associated with both H 2 O and CH 3 OH masers are in relative later evolutionary stage. The detection rate of H 2 O masers towards BGPS sources displaying evidence of the collapse phenomenon is 62.1 per cent, which suggests that most BGPS sources showing indications of collapse phenomena contain ongoing active star formation activities.

Description: We performed a 22 GHz H 2 O maser survey towards 221 Bolocam Galactic Plane Survey (BGPS) sources. We detected 107 H 2 O masers, of which 12 are new. The detection rate is 48.4 per cent for our sample. We obtained the positions of five new H 2 O masers via On The Fly (OTF) observations. The detection rate of H 2 O masers is correlated with continuum emission fluxes of BGPS sources at far-infrared, sub-millimetre and millimetre wavelengths. We employed the classification of Dunham et al. to classify the evolutionary stage of BGPS sources into Group 0, 1, 2, and 3. The detection rate and velocity range of H 2 O masers increases as the BGPS sources evolve from Group 1 to Group 3. The BGPS sources associated with both H 2 O and CH 3 OH masers are more compact than that associated with either only H 2 O or only CH 3 OH masers. This indicates that the sources associated with both H 2 O and CH 3 OH masers are in relative later evolutionary stage. The detection rate of H 2 O masers towards BGPS sources displaying evidence of the collapse phenomenon is 62.1 per cent, which suggests that most BGPS sources showing indications of collapse phenomena contain ongoing active star formation activities.

Description: In vehicular networks, since reliable end-to-end paths between data source and destination seldom exist, replication-based routing protocols are widely used to increase the delivery ratio and reduce the transfer delay. However, after a data message is delivered, its replicas still exist and greatly waste network resources, such as transmission bandwidth and storage spaces. In mobile multimedia communications, the large size of multimedia data greatly aggravates this situation. In this paper, we propose a GPS-based replica deletion scheme with anti-packet distribution for vehicular networks, namely RAD. It utilizes vehicle-to-vehicle and vehicle-to-roadside-unit communications to remove redundant data replicas by a certain number of anti-packets. A roadside unit at each crossing distributes its collected anti-packets to nearby vehicles moving for different directions according to the geographical locations of the to-be-deleted targets. This distribution increases the delivery probability of these anti-packets. Experiment results in a real taxi network show that, compared with others, RAD accelerates replica deletion with less extra overhead

Description: In this work, we aim to characterize high-mass clumps with infall motions. We selected 327 clumps from the Millimetre Astronomy Legacy Team 90-GHz survey, and identified 100 infall candidates. Combined with the results of He et al., we obtained a sample of 732 high-mass clumps, including 231 massive infall candidates and 501 clumps where infall is not detected. Objects in our sample were classified as pre-stellar, proto-stellar, H ii or photodissociation region (PDR). The detection rates of the infall candidates in the pre-stellar, proto-stellar, H ii and PDR stages are 41.2 per cent, 36.6 per cent, 30.6 per cent and 12.7 per cent, respectively. The infall candidates have a higher H 2 column density and volume density compared with the clumps where infall is not detected at every stage. For the infall candidates, the median values of the infall rates at the pre-stellar, proto-stellar, H ii and PDR stages are 2.6 x 10 –3 , 7.0 x 10 –3 , 6.5 x 10 –3 and 5.5 x 10 –3 M  yr –1 , respectively. These values indicate that infall candidates at later evolutionary stages are still accumulating material efficiently. It is interesting to find that both infall candidates and clumps where infall is not detected show a clear trend of increasing mass from the pre-stellar to proto-stellar, and to the H ii stages. The power indices of the clump mass function are 2.04 ± 0.16 and 2.17 ± 0.31 for the infall candidates and clumps where infall is not detected, respectively, which agree well with the power index of the stellar initial mass function (2.35) and the cold Planck cores (2.0).

Description: Massive star-forming regions with observed infall motions are good sites for studying the birth of massive stars. In this paper, 405 compact sources have been extracted from the APEX Telescope Large Area Survey of the Galaxy (ATLASGAL) compact sources that also have been observed in the Millimetre Astronomy Legacy Team 90-GHz (MALT90) survey during years 1 and 2. These observations are complemented with Spitzer GLIMPSE/MIPSGAL mid-IR survey data to help classify the elected star-forming clumps into three evolutionary stages: pre-stellar, proto-stellar and UCHII regions. The results suggest that 0.05 g cm –2 is a reliable empirical lower bound for the clump surface densities required for massive-star formation to occur. The optically thick HCO + (1-0) and HNC(1-0) lines, as well as the optically thin N 2 H + (1-0) line were used to search for infall motions towards these sources. By analysing the asymmetries of the optically thick HCO + (1-0) and HNC(1-0) lines and the mapping observations of HCO + (1-0), a total of 131 reliable infall candidates have been identified. The HCO + (1-0) line shows the highest occurrence of obvious asymmetric features, suggesting that it may be a better infall motion tracer than other lines such as HNC(1-0). The detection rates of infall candidates towards pre-stellar, proto-stellar and UCHII clumps are 0.3452, 0.3861 and 0.2152, respectively. The relatively high detection rate of infall candidates towards UCHII clumps indicates that many UCHII regions are still accreting matter. The peak column densities and masses of the infall candidates, in general, display an increasing trend with progressing evolutionary stages. However, the rough estimates of the mass infall rate show no obvious variation with evolutionary stage.

Description: For extensional wave propagation along a cylindrical pipe, there exists a natural stopband in the frequency range between the first and second modes. This study explores the feasibility and practicality of building a drill collar acoustic extensional-wave isolator by combining the stopbands of pipes of different thicknesses. Numerical modelling shows that this is indeed possible and a stopband of designated width can be obtained using an optimization procedure. Laboratory measurement on an optimized design further verified this concept. The result provides a viable approach for the acoustic isolation design of a logging while drilling acoustic tool.

Description: Papillary thyroid carcinoma (PTC) is the most common type of thyroid cancer. However, we know little of mutational spectrum in the Chinese population. Thus, here we report the identification of somatic mutations for Chinese PTC using 402 tumor-normal pairs (Discovery: 91 pairs via exome sequencing; validation: 311 pairs via Sanger sequencing). We observed three distinct mutational signatures, evidently different from the two mutational signatures among Caucasian PTCs. Ten significantly mutated genes were identified, most previously uncharacterized. Notably, we found that long non-coding RNA (lncRNA) GAS8-AS1 is the secondary most frequently altered gene and acts as a novel tumor suppressor in PTC. As a mutation hotspot, the c.713A〉G/714T〉C dinucleotide substitution was found among 89.1% patients with GAS8-AS1 mutations and associated with advanced PTC disease ( P = 0.009). Interestingly, the wild-type lncRNA GAS8-AS1 (A 713 T 714 ) showed consistently higher capability to inhibit cancer cell growth compared to the mutated lncRNA (G 713 C 714 ). Further studies also elucidated the oncogene nature of the G protein-coupled receptor LPAR4 and its c.872T〉G (p.Ile291Ser) mutation in PTC malignant transformation. The BRAF c.1799T〉A (p.Val600Glu) substitution was present in 59.0% Chinese PTCs, more frequently observed in patients with lymph node metastasis ( P = 1.6 x 10 –4 ). Together our study defines a exome mutational spectrum of PTC in the Chinese population and highlights lncRNA GAS8-AS1 and LPAR4 as potential diagnostics and therapeutic targets.

Description: Transcription factors (TFs) play key roles in both development and stress responses. By integrating into and rewiring original systems, novel TFs contribute significantly to the evolution of transcriptional regulatory networks. Here, we report a high-confidence transcriptional regulatory map covering 388 TFs from 47 families in Arabidopsis . Systematic analysis of this map revealed the architectural heterogeneity of developmental and stress response subnetworks and identified three types of novel network motifs that are absent from unicellular organisms and essential for multicellular development. Moreover, TFs of novel families that emerged during plant landing present higher binding specificities and are preferentially wired into developmental processes and these novel network motifs. Further unveiled connection between the binding specificity and wiring preference of TFs explains the wiring preferences of novel-family TFs. These results reveal distinct functional and evolutionary features of novel TFs, suggesting a plausible mechanism for their contribution to the evolution of multicellular organisms.

Description: Scattering due to small-scale heterogeneities in the rock formation surrounding a wellbore can significantly change the acoustic waveform from a logging measurement which in turn can be used to characterize the formation heterogeneities. This study simulates the elastic heterogeneity scattering in monopole and dipole acoustic logging and analyse the resulting effects on the waveforms. The results show that significant coda waves are generated in both monopole and dipole waveforms and the dipole coda is dominated by S -to- S scattering, which can be effectively utilized to diagnose the heterogeneity in the rock formation. The coda wave modelling and analysis were used to characterize dipole acoustic data logged before and after fracturing a reservoir interval, with significant coda wave in the after-fracturing data indicating fracturing-induced heterogeneous property change in the rock volume surrounding the borehole.

Description: 〈span〉〈div〉SUMMARY〈/div〉With the comparison to the resistivity ultra-deep measurement, the single-well reflection survey in acoustic logging-while-drilling (ALWD) measurement lags far behind, especially ALWD dipole measurement has long been thought to be little added value. In this paper, we extended the dipole shear-wave (〈span〉S〈/span〉-wave) reflection survey technology in wireline logging into ALWD and demonstrated the theoretical feasibility of adopting a dipole source–receiver system to perform ALWD reflection survey. For this purpose, we investigated the radiation patterns of radiant〈span〉SH, SV〈/span〉 and 〈span〉P〈/span〉 waves, the energy fluxes of guided and radiant waves and their acoustical radiation efficiencies from an LWD dipole acoustic source by comparisons with the wireline results. The analysis results reveal that a dominant excitation-frequency band does exist in ALWD dipole 〈span〉S〈/span〉-wave reflection. Consequently, the expected excitation frequency should be located in the band of the signal with high radiation efficiency, guaranteeing the best radiation performance. In fast formations, 〈span〉SH〈/span〉 wave is the best candidate for ALWD reflection survey due to its highest radiation efficiency. In contrast, the dominant excitation-frequency band of 〈span〉SH〈/span〉 wave gets wider in a slow formation. Besides, the 〈span〉SV〈/span〉- and 〈span〉P〈/span〉-wave radiation efficiencies are also remarkable, implying that both waves can also be used for ALWD reflection survey in slow formations. We expounded the 〈span〉SH-, SV-〈/span〉 and 〈span〉P〈/span〉-reflection behaviours at three typical excitation frequencies by our 3-D finite difference. Simulations to single-well reflection validate the key role of dominant excitation-frequency band and demonstrate the theoretical feasibility of applying the technology to ALWD. Our results can guide the design and measurement methods of ALWD dipole 〈span〉S〈/span〉-wave reflection survey tool, which could have extensive application prospect for geo-steering.〈/span〉