779 research outputs found
Embryo impacts and gas giant mergers II: Diversity of Hot Jupiters' internal structure
We consider the origin of compact, short-period, Jupiter-mass planets. We
propose that their diverse structure is caused by giant impacts of embryos and
super-Earths or mergers with other gas giants during the formation and
evolution of these hot Jupiters. Through a series of numerical simulations, we
show that typical head-on collisions generally lead to total coalescence of
impinging gas giants. Although extremely energetic collisions can disintegrate
the envelope of gas giants, these events seldom occur. During oblique and
moderately energetic collisions, the merger products retain higher fraction of
the colliders' cores than their envelopes. They can also deposit considerable
amount of spin angular momentum to the gas giants and desynchronize their spins
from their orbital mean motion. We find that the oblateness of gas giants can
be used to infer the impact history. Subsequent dissipation of stellar tide
inside the planets' envelope can lead to runaway inflation and potentially a
substantial loss of gas through Roche-lobe overflow. The impact of super-Earths
on parabolic orbits can also enlarge gas giant planets' envelope and elevates
their tidal dissipation rate over 100 Myr time scale. Since giant
impacts occur stochastically with a range of impactor sizes and energies, their
diverse outcomes may account for the dispersion in the mass-radius relationship
of hot Jupiters.Comment: 19 pages, 7 figures, 7 tables. Accepted for publication in MNRA
TRANSCRIPT PROFILING AS A METHOD TO STUDY FRUIT MATURATION, TREE-RIPENING, AND THE ROLE OF "TREE FACTOR" IN 'GALA' AND 'FUJI' APPLES
'Gala' and 'Fuji' are two high-quality apple (Malus domestica Borkh) cultivars. Their fruits mature and tree-ripen over a long period of time, and are resistant to pre-harvest drop. "Tree factor," a putative inhibitor of system 2 ethylene production is hypothesized to account for differences in ethylene production between attached and detached apple fruits. Three years of field data revealed two distinct patterns of maturation and ripening behavior in these two cultivars. 'Gala,' an early cultivar, demonstrated a typical positive "tree factor." Studies of the ripening pattern of 'Fuji' apple, which is a late-maturing cultivar, did not. 'Fuji' data were confounded by cold weather in the late fall. The natural progression of tree-ripening did not lead to the high concentrations of internal ethylene routinely measured in stored fruits. The stimulation of ethylene found in picked 'Gala' fruits ripened in the orchard might be explained by wounding stress coupled with a loss of nutrients and the water stress. Our alternative explanation for "tree factor" is the effect of continued termination of the phloem and xylem connection. The strength of the "tree factor" declined as 'Gala' fruit maturity progressed. Therefore, the "tree factor" tends to be more obvious in fruits with shorter growing period that mature during warm weather.
To investigate differential gene expression that accompanies maturation and tree ripening, we used cDNA-AFLP (Amplified Fragment Length Polymorphism) to identify changes in transcript profiling during tree-ripening, and in the ripening of harvested fruits. Two hundred differentially-expressed transcript-derived fragments were isolated from 'Gala.' Ripening-related genes including those known to function in the key processes of defense and stress, cell wall degradation, pigment production and aroma biosynthesis were identified. Clones similar to housekeeping genes involved in protein biosynthesis and degradation, intracellular trafficking and sorting, cell structure and mobility, and metabolism-associated genes were also isolated. Expression patterns of these transcript-derived fragments were verified by using a different 'Gala' sample set on microarray and/or Northern blots. Our study supports the hypothesis that many ripening processes are under transcriptional control and that most of these differentially-expressed genes are highly conserved in fruits
Research on the Moderating Role of Authorized Leadership in the Relationship Between Mental Capital and Innovative Performance of Knowledge-Oriented Employees
In this paper, through the collection and processing of 206 questionnaires of knowledge-oriented employees and their supervisors to match the effective data, empirical research on the impact of the psychological capital of knowledge-oriented staff on innovative performance through the intermediary mechanism, and the moderating role of authorized leadership in the intermediary mechanism. The results show that the mental capital of knowledge-based staff can influence the intrinsic mechanism of innovation performance through work effort, and authorized leaders can positively adjust the influence of psychological capital on work effort. Meanwhile, authorized leaders can adjust the influence of knowledge workers ' work on their innovation performance. On this basis, this paper proposes that managers can influence the relationship between mental capital of knowledge-based employees and their work and innovation performance through empowering leadership style and give full play to the positive role of knowledge workers in enterprise innovation. Keywords: Empowering Leadership, Knowledge workers, Innovative behavior, Trust mechanis
Research on the Affective Mechanism of Authorized Leaders' Influence on the Innovation Performance of Knowledge Workers
In this paper, we have collected and processed 233 effective data of paired survey questionnaires for knowledge workers and their supervisors, and empirically studied the affective mechanism of authorized leaders' influence on the innovative performance of knowledge workers. The results show that authorized leadership can positively influence the positive emotion of knowledge workers; it has negative influence on the knowledge worker's negative emotion, and ultimately affects the knowledge worker's innovation performance. Meanwhile, the Leader-Member eXchange (LMX) plays a positive role in the positive relationship between the authorized leadership and the knowledge worker. It plays a negative moderating role in the negative affective relationship between the authorized leadership and the knowledge worker. On this basis, this paper posits that leaders need to manage the innovative behavior of knowledge workers by implementing the authoritative leadership style; meanwhile, the authorized leaders should have more and better communication and interaction with the knowledge workers, which will effectively promote the positive emotion of the knowledge workers by authorized leadership style. And also, to further on dissolve their negative emotion, and finally improve the knowledge-oriented staff's innovative performance, in order to give full play to the knowledge of staff in the role of enterprise innovation. Keywords: Authorized leaders; Knowledge workers; Innovative performance; Trust mechanism
Comparing journal and paper level classifications of science
The classification of science into disciplines is at the heart of bibliometric analyses. While most classifications systems are implemented at the journal level, their accuracy has been questioned, and paper-level classifications have been considered by many to be more precise. However, few studies investigated the difference between journal and the paper classification systems. This study addresses this gap by comparing the journal- and paper-level classifications for the same set of papers and journals. This isolates the effects of classification precision (i.e., journal- or paper-level) to reveal the extent of paper misclassification. Results show almost half of papers could be misclassified in journal classification systems. Given their importance in the construction and analysis of bibliometric indicators, more attention should be given to the robustness and accuracy of these disciplinary classifications schemes
Diagnostic value of mammography density of breast masses by using deep learning
ObjectiveIn order to explore the relationship between mammographic density of breast mass and its surrounding area and benign or malignant breast, this paper proposes a deep learning model based on C2FTrans to diagnose the breast mass using mammographic density.MethodsThis retrospective study included patients who underwent mammographic and pathological examination. Two physicians manually depicted the lesion edges and used a computer to automatically extend and segment the peripheral areas of the lesion (0, 1, 3, and 5 mm, including the lesion). We then obtained the mammary glands’ density and the different regions of interest (ROI). A diagnostic model for breast mass lesions based on C2FTrans was constructed based on a 7: 3 ratio between the training and testing sets. Finally, receiver operating characteristic (ROC) curves were plotted. Model performance was assessed using the area under the ROC curve (AUC) with 95% confidence intervals (CI), sensitivity, and specificity.ResultsIn total, 401 lesions (158 benign and 243 malignant) were included in this study. The probability of breast cancer in women was positively correlated with age and mass density and negatively correlated with breast gland classification. The largest correlation was observed for age (r = 0.47). Among all models, the single mass ROI model had the highest specificity (91.8%) with an AUC = 0.823 and the perifocal 5mm ROI model had the highest sensitivity (86.9%) with an AUC = 0.855. In addition, by combining the cephalocaudal and mediolateral oblique views of the perifocal 5 mm ROI model, we obtained the highest AUC (AUC = 0.877 P < 0.001).ConclusionsDeep learning model of mammographic density can better distinguish benign and malignant mass-type lesions in digital mammography images and may become an auxiliary diagnostic tool for radiologists in the future
Correlation of the Cerebral Microvascular Blood Flow with Brain Temperature and Electro-Acupuncture Stimulation
ObjectiveTo investigate the relationship between the temperature and the microvascular blood flow of the cerebral cortex, and the influence of electro-acupuncture (EA) on the cortical microcirculation.MethodsHigh temperature spots on the anterior ectosylvian and low temperature spots on the posterior suprasylvian on the cortical surface of 20 cats were identified using cortical infrared thermography (CIT); the blood flow in the microcirculation on these spots was measured with laser-Doppler flowmetry. EA was given at Zusanli (ST 36) and changes in the blood flow in the cerebral cortex microcirculation were detected.Results1) The mean temperatures on the high (34.83±0.24°C) and low (32.28±0.27°C) temperature spots were significantly different (P<0.001); this was indicative of a temperature difference on the cortical surface; 2) The average blood flow in the microcirculation of the high (266.8±19.2 PU) and low (140.8±9.9 PU) temperature spots was significantly different (P<0.001). 3) On the cortical high temperature spots, the mean blood flow in the microcirculation significantly increased from 266.8±86.8 PU before EA, to 422.5±47.4 PU following 5 minutes of EA (58.35%; P<0.01), and 431.8±52.8 PU 5 minutes after ceasing EA (61.84%; P<0.01). 4) On the low temperature spots, there were no significant differences in blood flow following 5 minutes of EA (146.3±11.5 PU), and 5 minutes after ceasing EA (140.5±11.6 PU), when compared with that before acupuncture (140.8±9.9 PU; P>0.9).ConclusionThe high temperature spots of the cortex are active functional regions of neurons with higher blood flow and a stronger response to EA. EA induces a significant increase in blood flow in the high temperature spots of the cortex
Discovery of four gravitational lensing systems by clusters in the SDSS DR6
We report the discovery of 4 strong gravitational lensing systems by visual
inspections of the Sloan Digital Sky Survey images of galaxy clusters in Data
Release 6 (SDSS DR6). Two of the four systems show Einstein rings while the
others show tangential giant arcs. These arcs or rings have large angular
separations (>8") from the bright central galaxies and show bluer color
compared with the red cluster galaxies. In addition, we found 5 probable and 4
possible lenses by galaxy clusters.Comment: 6 pages, 3 figures. Added referenc
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