3,205 research outputs found

    Log-Poisson Hierarchical Clustering of Cosmic Neutral Hydrogen and Ly-alpha Transmitted Flux of QSO Absorption Spectrum

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    we study, in this paper, the non-Gaussian features of the mass density field of neutral hydrogen fluid and the Ly-alpha transmitted flux of QSO absorption spectrum from the point-of-view of self-similar log-Poisson hierarchy. It has been shown recently that, in the scale range from the onset of nonlinear evolution to dissipation, the velocity and mass density fields of cosmic baryon fluid are extremely well described by the She-Leveque's scaling formula, which is due to the log-Poisson hierarchical cascade. Since the mass density ratio between ionized hydrogen to total hydrogen is not uniform in space, the mass density field of neutral hydrogen component is not given by a similar mapping of total baryon fluid. Nevertheless, we show, with hydrodynamic simulation samples of the concordance Λ\LambdaCDM universe, that the mass density field of neutral hydrogen, is also well described by the log-Poisson hierarchy. We then investigate the field of Lyα\alpha transmitted flux of QSO absorption spectrum. Due to redshift distortion, Lyα\alpha transmitted flux fluctuations are no longer to show all features of the log-Poisson hierarchy. However, some non-Gaussian features predicted by the log-Poisson hierarchy are not affected by the redshift distortion. We test these predictions with the high resolution and high S/N data of quasars Lyα\alpha absorption spectra. All results given by real data, including β\beta-hierarchy, high order moments and scale-scale correlation, are found to be well consistent with the log-Poisson hierarchy. We compare the log-Poisson hierarchy with the popular log-normal model of the Lyα\alpha transmitted flux. The later is found to yield too strong non-Gaussianity at high orders, while the log-Poisson hierarchy is in agreement with observed data.Comment: 24 pages, 9 figures, accepted by Ap

    Discovery of Protein Phosphorylation Motifs through Exploratory Data Analysis

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    BACKGROUND: The need for efficient algorithms to uncover biologically relevant phosphorylation motifs has become very important with rapid expansion of the proteomic sequence database along with a plethora of new information on phosphorylation sites. Here we present a novel unsupervised method, called Motif Finder (in short, F-Motif) for identification of phosphorylation motifs. F-Motif uses clustering of sequence information represented by numerical features that exploit the statistical information hidden in some foreground data. Furthermore, these identified motifs are then filtered to find "actual" motifs with statistically significant motif scores. RESULTS AND DISCUSSION: We have applied F-Motif to several new and existing data sets and compared its performance with two well known state-of-the-art methods. In almost all cases F-Motif could identify all statistically significant motifs extracted by the state-of-the-art methods. More importantly, in addition to this, F-Motif uncovers several novel motifs. We have demonstrated using clues from the literature that most of these new motifs discovered by F-Motif are indeed novel. We have also found some interesting phenomena. For example, for CK2 kinase, the conserved sites appear only on the right side of S. However, for CDK kinase, the adjacent site on the right of S is conserved with residue P. In addition, three different encoding methods, including a novel position contrast matrix (PCM) and the simplest binary coding, are used and the ability of F-motif to discover motifs remains quite robust with respect to encoding schemes. CONCLUSIONS: An iterative algorithm proposed here uses exploratory data analysis to discover motifs from phosphorylated data. The effectiveness of F-Motif has been demonstrated using several real data sets as well as using a synthetic data set. The method is quite general in nature and can be used to find other types of motifs also. We have also provided a server for F-Motif at http://f-motif.classcloud.org/, http://bio.classcloud.org/f-motif/ or http://ymu.classcloud.org/f-motif/

    Potential protective role of hydrogen against cisplatininduced side effects during chemotherapy: A mini-review of a novel hypothesis for antagonism of hydrogen

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    Purpose: To review the potential protective role of hydrogen against cisplatin-induced side effects during chemotherapy.Methods: We searched PubMed and SCOPUS using the following keywords and combinations in titles, keywords, abstracts and full texts: cisplatin; side effects; chemotherapy; tumor; toxicity; hydrogen; reactive oxidative species; and ischemic reperfusion.Results: The pathogenesis of cisplatin-induced side effects is suggested based on the increased level of reactive oxidative species (ROS). Cisplatin induces ROS-dependent platelet apoptosis via the extracellular signal-regulated kinase (ERK) signaling pathway, which might have contributed to cisplatininduced hematotoxicity, and in particular, thrombocytopenia. Molecular hydrogen has been shown to have therapeutic effects against damage to various organs (especially kidney, brain and liver) caused by ischemic reperfusion (IR) through selective elimination of the most cytotoxic ROS hydrogen radicals without affecting other types of ROS involved in signal transduction in vitro and in vivo.Conclusion: Hydrogen may not only alleviate hematotoxicity in patients with hemorrhagic tendencies during cisplatin-based chemotherapy, but also has a potential protective effect against other side effects induced by cisplatin.Keywords: Reactive oxygen species, Hydrogen radicals, Cisplatin, Hepatotoxicity, Chemotherapy, Side effects, Antagonis

    Square Key Matrix Management Scheme in Wireless Sensor Networks

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    In this paper we propose a symmetric cryptographic approach named Square Key Matrix Management Scheme (SKMaS) in which a sensor node named Key Distribution Server (KDS) is responsible for the security of key management. When the system starts up, the KDS sends its individual key and two sets of keys to sensor nodes. With the IDs, any two valid sensor nodes, e.g. i and j, can individually identify the corresponding communication keys (CKs) to derive a dynamic shared key (DSK) for encrypting/decrypting messages transmitted between them. When i leaves the underlying network, the CKs and the individually keys currently utilized by i can be reused by a newly joining sensor, e.g. h. However, when h joins the network, if no such previously-used IDs are available, h will be given a new ID, CKs and the individually key by the KDS. The KDS encrypts the CKs, with which an existing node q can communicate with h, with individual key so that only q rather than h can correctly decrypt the CKs. The lemmas and security analyses provided in this paper prove that the proposed system can protect at least three common attacks

    Three-Dimensional Reconstruction of Thoracic Structures: Based on Chinese Visible Human

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    We managed to establish three-dimensional digitized visible model of human thoracic structures and to provide morphological data for imaging diagnosis and thoracic and cardiovascular surgery. With Photoshop software, the contour line of lungs and mediastinal structures including heart, aorta and its ramus, azygos vein, superior vena cava, inferior vena cava, thymus, esophagus, diaphragm, phrenic nerve, vagus nerve, sympathetic trunk, thoracic vertebrae, sternum, thoracic duct, and so forth were segmented from the Chinese Visible Human (CVH)-1 data set. The contour data set of segmented thoracic structures was imported to Amira software and 3D thorax models were reconstructed via surface rendering and volume rendering. With Amira software, surface rendering reconstructed model of thoracic organs and its volume rendering reconstructed model were 3D reconstructed and can be displayed together clearly and accurately. It provides a learning tool of interpreting human thoracic anatomy and virtual thoracic and cardiovascular surgery for medical students and junior surgeons

    A way to learn : the service learning between Indonesia (SCU) and Taiwan (FJU)

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    Gills and Maclellan (2010) conducted a 1999-2009 systemic literature review service learning in nursing education, outcomes suggest that students who participate in international programs having an increase in self-perceived cultural competency, encouraging lifelong commitment to continue serving, developing students into a positive force of change in healthcare abroad and within their own communities. The purpose of this study is in depth to analyze nursing students\u27 learning process through the service learning. Design: Action research method was used and a total number of 6 nursing students were participated in this study. One Taiwanese and one Indonesia students as a team shared a bed and lived with Indonesia family for 11 days. During this period students logs, field notes, reflection sheets and team working records as raw materials together to be used as content analysis, the reliability and validity is based on Lincoln and Guba (1985) proposed vetting reliability and validity of qualitative research methods. Results: After intensively living and working with Indonesia students and family in this international service learning program, the results come up as an agricultural process. It is improving students\u27 cross-culture communication in spread period. Follow by cultivated period that participants established cross-cultural sensitivities and culture respect. In the final harvest period, through the serving activities, participant fulfilled the role as givers and receivers among Indonesia partners and families and able to understand the meaning of love. In conclusion, this study confirmed the previous studies outcomes and showed the dynamic interaction amongst nursing students who joined service learning, and enhanced students understanding among the cultures, with the respect on inner or outer levels
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