Infall, Fragmentation and Outflow in Sgr B2

Observations of H$_{2}$CO lines and continuum at 1.3 mm towards Sgr B2(N) and Sgr B2(M) cores were carried out with the SMA. We imaged H$_{2}$CO line absorption against the continuum cores and the surrounding line emission clumps. The results show that the majority of the dense gas is falling into the major cores where massive stars have been formed. The filaments and clumps of the continuum and gas are detected outside of Sgr B2(N) and Sgr B2(M) cores. Both the spectra and moment analysis show the presence of outflows from Sgr B2(M) cores. The H$_{2}$CO gas in the red-shifted outflow of Sgr B2(M) appears to be excited by a non-LTE process which might be related to the shocks in the outflow.Comment: 5 pages, 3 figures, Published in J. Physics Conference Serie

Superconducting fluctuations and charge-4ee plaquette state at strong coupling

Recent experiments indicate that superconducting fluctuations also play an important role in overdoped cuprates. Here we apply the static auxiliary field Monte Carlo approach to study phase correlations of the pairing fields in a microscopic model with spin-singlet pairing interaction. We find that the short- and long-range phase correlations are well captured by the phase mutual information, which allows us to construct a theoretical phase diagram containing the uniform $d$-wave superconducting region, the phase fluctuating region, the local pairing region, and the disordered region. We show that the gradual development of phase coherence has a number of consequences on spectroscopic measurements, such as the development of the Fermi arc and the anisotropy in the angle-resolved spectra, scattering rate, entropy, specific heat, and quasiparticle dispersion, in good agreement with experimental observations. For strong coupling, our Monte Carlo simulation reveals an unexpected charge-4$e$ plaquette state with $d$-wave bonds, which competes with the uniform $d$-wave superconductivity and exhibits a U-shaped density of states

Infall and Outflow of Molecular Gas in Sgr B2

Observations of two $H_2CO (3_{03}-2_{02} and 3_{21}-2_{20})$ lines and continuum emission at 1.3 mm toward Sgr B2(N) and Sgr B2(M) have been carried out with the SMA. The mosaic maps of Sgr B2(N) and Sgr B2(M) in both continuum and lines show a complex distribution of dust and molecular gas in both clumps and filaments surrounding the compact star formation cores. We have observed a decelerating outflow originated from the Sgr B2(M) core, showing that both the redshifted and blueshifted outflow components have a common terminal velocity. This terminal velocity is $58 ± 2 km s^{−1}$. It provides an excellent method for determination of the systematic velocity of the molecular cloud. The SMA observations have also shown that a large fraction of absorption against the two continuum cores is redshifted with respect to the systematic velocities of Sgr B2(N) and Sgr B2(M), respectively, suggesting that the majority of the dense molecular gas is flowing into the two major cores where massive stars have been formed. We have solved the radiative transfer in a multilevel system with LVG approximation. The observed $H_2CO$ line intensities and their ratios can be adequately fitted with this model for the most of the gas components. However, the line intensities between the higher energy level transition $H_2CO(3_{21}-2_{20})$ and the lower energy level transition $H_2CO(3_{03}-2_{02})$ is reversed in the redshifted outflow region of Sgr B2(M), suggesting the presence of inversion in population between the ground levels in the two K ladders $(K_{−1} = 0 and 2)$. The possibility of weak maser processes for the $H_2CO$ emission in Sgr B2(M) is discussed.Astronom

Spatiotemporal Variability and Change of the South China Spring Precipitation during 1961–2012

We analyze precipitation data from 47 meteorological stations spanning between 1961 and 2012 and NCEP/NCAR reanalysis to understand spatiotemporal variability and change of spring precipitation of South China and their relations to atmospheric circulations. Empirical orthogonal function (EOF) analysis and rotated EOF (REOF) are used to reveal dominant spatial structures of precipitation anomaly and Mann-Kendall testing method to determine the temporal locations of abrupt changes during the analyzed time span. We find that the first spatial mode of the spring precipitation of the South China has a domain uniform structure; the second is dominated by a spatial dipole; and the third contains six variability centers. 1980s was the decade of the largest amount of precipitation while 1960s the decade of the smallest amount of precipitation. The spring precipitation also appeared to have a decreasing trend since 2000. We also find that spring precipitation of the South China has experienced a few abrupt changes: sudden increment at 1964, sudden decrement at 2002, and sudden increment at 1995. In addition to these abrupt changes, the precipitation could also be characterized by variability of multiple temporal scales, with dominant periodicities of 4 years, 8 years, and 14 years. The South China spring precipitation is also closely tied to the atmospheric circulations: when Aleutian Low strengthens, westerly weakens, and the center of the Western Pacific subtropical high shifts southeastward in the early spring; and the South China precipitation tends to be abundant (positive anomaly). In contrast, when Ural ridge strengthens, the southern branch of the East Asian trough weakens and the Western Pacific subtropical high shifts northwestward in the early spring, the South China precipitation tends to be reduced (negative anomaly)

不同年龄和性别精神分裂症患者脑白质扩散张量成像的临床研究*

Objective: Diffusion tensor imaging (DTI) was used to analyze the changes of white matter fiber FA in patients with schizophrenia of different ages and genders, and to explore the reference of clinical imaging. Methods: Retrospective analysis of the clinical diagnosis of schizophrenia patients and healthy subjects in all 50 cases, were given routine examination of brain MRI parallel diffusion tensor imaging, comparison of different age and gender in different parts of the brain white matter changes of FA value. Results: (1) the FA values of white matter in different age groups were different between the patients and the normal group (P < 0.05). The normal group right superior frontal gyrus, left parietal lobe and left anterior cingulate gyrus of the cerebral white matter fiber FA value increased gradually before the age of 30, at the age of 30 and reached the peak gradually decreased after 30 years old. The left frontal gyrus and corpus callosum in patients with group pressure (after) of cerebral white matter fiber FA value increased gradually before the age of 30, at the age of 30 and reached the peak gradually decreased after 30 years old. (2) the FA values of white matter in different parts of male and female patients were different (P < 0.05). The white matter fiber FA in the left anterior capsule of the normal group was higher in males than in females. The FA value of bilateral occipital white matter in male patients was lower than that in female; the FA values of the central white matter in the left and right sides of the brain stem were higher in males than in females. Conclusion: the changes of FA value in the white matter of some parts of the brain in the normal group and the patient group are influenced by age and sex.  目的  运用扩散张量成像分析不同年龄和性别精神分裂症患者脑白质纤维FA值的变化，探讨临床影像学参考依据。方法  回顾性分析经临床确诊的精神分裂症患者和健康者各50例，均作颅脑MRI常规检查并行扩散张量成像，比较不同年龄和性别各部位脑白质FA值变化特点。结果  （1）患者组和正常组不同年龄各部位脑白质FA值有差异（P＜0.05）。正常组中右额上回、左顶叶及左扣带回前部脑白质纤维FA值在30岁前逐渐增高，30岁达高峰，在30岁后逐渐减少。患者组中左额上回及胼胝体压部（后）脑白质纤维FA值在30岁前逐渐增高，30岁达高峰，在30岁后逐渐减少。（2）患者组和正常组男女各部位脑白质FA值有差异（P＜0.05）。发现正常组中左侧内囊前肢脑白质纤维FA值男性较女性高。患者组中双侧枕叶脑白质纤维FA值男性较女性低；脑干左右侧中心脑白质FA值男性较女性高。结论  正常组和患者组大脑某些部位脑白质纤维FA值量的变化受年龄、性别的影响