383 research outputs found

    Reliability analysis of the internet of things using Space Fault Network

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    The Internet of Things (IoT) is a network topology structure based on the interconnection of many nodes. It realizes the basic functions of IoT through the transmission of information, data, and energy between the nodes. To study the reliability of Internet of Things Network Topology (IoTNT) structure, we must abstract IoT as network topology and study the reliability of the network itself from the topology structure. This paper attempts to apply the Space Fault Network (SFN) to the study the reliability of IoTNT. To achieve this goal, the nodes and edges of IoTNT are equivalent to events and connections of SFN respectively. A structure analysis method based on SFN is proposed and used to study the reliability of IoTNT. At the same time, the influence of possible logical relationship between nodes on the reliability of IoTNT is studied. According to the SFN structure representation methods (SFNSRMs), considering different network structures and induced modes, the analysis methods and calculation methods of the evolution process of target event are given. An example is given to illustrate the analysis and calculation process. The research provides the new methods for the reliability study of IoT and the development of SFN

    Obesity Prevalence and Dietary Intake of Antioxidants in Native American Adolescents

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    Antioxidants are well known for possessing anti-inflammatory properties, which can reduce the risk of chronic disease and obesity. However, very little research has been done to examine antioxidant intake among adolescent minority populations such as Native American adolescents. Our study examined the significance of antioxidant intake among Native American adolescents at an urban residential high school in Southern California. Our study population consisted of 183 male and female Native American adolescents, 14-18 years of age, representing 43 tribes from across the United States. Students' primary source of meals was provided by the school food service. Based on the BMI calculations, the rate of obesity within our population was 38% for males and 40% for females, more than two-fold the national rate indicated by NHANESIII data. We used the Harvard School of Public Health Youth/Adolescent Questionnaire (HSPH YAQ), a semi-quantitative food frequency questionnaire, to examine antioxidant nutrient intake and evaluate the differences in the intake between normal and obese weight students. Statistical analysis of the results showed that intakes of vitamins C, E, and lycopene were the antioxidant nutrients found to be significantly different between normal and obese weight students and intakes of these nutrients were found to be higher among normal weight students (p-values = 0.02451, 0.00847, and 0.04928, respectively). These results suggest that dietary intake of antioxidants could be increased among Native American adolescents. Further research is needed to confirm our findings and identify effective ways for school food service to incorporate antioxidant rich foods into school menus

    Rabbit and Human Non-Keratinising Stratified Squamous Oesophageal Epithelium Displays Similar Microridge Structure by Scanning Electron Microscopy

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    Since the oesophageal epithelium of common laboratory animals, rats and mice, is keratinized it is unsuitable for comparison with typical non-keratinized stratified squamous human epithelium. It is thus important to find a suitable animal model for the study of human oesophageal tissue changes. This study investigated the microridge structure of immature and adult rabbit specimens, and adult human biopsies by scanning electron microscopy and morphometry. The investigation revealed a similarity between typical squamous human and adult rabbit oesophageal mucosal epithelium. While human epithelium specimens subdivided into two other groups (non-typical squamous and non-squamous); all typical squamous human biopsies were from patients who had normal endoscopy reports and no reflux symptoms. The surface cells of typical squamous human epithelium displayed complex microridge patterns (64% of cell surface) but patterns in non-typical squamous specimens were more variable (38%) (P \u3c 0.001) and cell boundaries less obvious. Rabbit squames displayed clear microridge patterns with an elevation in the percentage of cell surface covered by microridges, with increasing age, from immature to adult specimens (P \u3c 0.001). There was no statistically significant differences between adult rabbit, and \u27typical squamous\u27 human biopsies (range 51-65%), results which suggest potential use of a rabbit model to study changes in human oesophageal tissue

    A Statistical Study of the Subauroral Polarization Stream Over North American Sector Using the Millstone Hill Incoherent Scatter Radar 1979- 2019 Measurements

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    This work conducts a statistical study of the subauroral polarization stream (SAPS) feature in the North American sector using Millstone Hill incoherent scatter radar measurements from 1979 to 2019, which provides a comprehensive SAPS climatology using a significantly larger database of radar observations than was used in seminal earlier works. Key features of SAPS and associated electron density (Ne), ion temperature (Ti), and electron temperature (Te) are investigated using a superposed epoch analysis method. The characteristics of these parameters are investigated with respect to magnetic local time, season, geomagnetic activity, solar activity, and interplanetary magnetic field (IMF) orientation, respectively. The main results are as follows: (1) Conditions for SAPS are more favorable for dusk than near midnight, for winter compared to summer, for active geomagnetic periods compared to quiet time, for solar minimum compared to solar maximum, and for IMF conditions with negative By and negative Bz. (2) SAPS is usually associated with a midlatitude trough of 15- 20% depletion in the background density. The SAPS- related trough is more pronounced in the postmidnight sector and near the equinoxes. (3) Subauroral ion and electron temperatures exhibit a 3- 8% (50- 120 K) enhancement in SAPS regions, which tend to have higher percentage enhancement during geomagnetically active periods and at midnight. Ion temperature enhancements are more favored during low solar activity periods, while the electron temperature enhancement remains almost constant as a function of the solar cycle. (4) The electron thermal content, Te- à - Ne, in the SAPS associated region is strongly dependent on 1/Ne, with Te exhibiting a negative correlation with respect to Ne.Key PointsKey features of North American SAPS and associated Ne, Ti, and Te were analyzed using four decade Millstone Hill IS radar measurementsNorth American SAPS climatology in terms of MLT, season, geomagnetic activity, solar activity, and IMF condition was comprehensively studiedBoth ion and electron temperatures exhibit moderate enhancement around SAPS, with similar geomagnetic but different solar activity dependencePeer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/163417/2/jgra56052_am.pdfhttp://deepblue.lib.umich.edu/bitstream/2027.42/163417/1/jgra56052.pd

    Episodic Occurrence of Field‐Aligned Energetic Ions on the Dayside

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    The tens of kiloelectron volt ions observed in the ring current region at L ~ 3–7 generally have pancake pitch angle distributions, that is, peaked at 90°. However, in this study, by using the Van Allen Probe observations on the dayside, unexpectedly, we have found that about 5% time, protons with energies of ~30 to 50 keV show two distinct populations, having an additional field‐aligned population overlapping with the original pancake population. The newly appearing field‐aligned populations have higher occurrence rates at ~12–16 magnetic local time during geomagnetically active times. In particular, we have studied eight such events in detail and found that the source regions are located around 12 to 18 magnetic local time which coincides with our statistical result. Based on the ionospheric and geosynchronous observations, it is suggested that these energetic ions with field‐aligned pitch angle distributions probably are accelerated near postnoon in association with ionospheric disturbances that are triggered by tail injections.Plain Language SummaryProtons of different sources have different pitch angle distributions (PADs). For example, warm plasma cloak protons, which come directly from the ionosphere, have field‐aligned PADs, while ring current protons that generally originate from tail plasma sheet have pancake‐shaped PADs. In this study, unexpectedly, we have found that about 5% of the time on the dayside, protons of ring current energies show two distinct populations according to their PADs: higher fluxes of field‐aligned populations overlapping with the original pancake populations. The newly appeared field‐aligned populations have higher occurrence rates at ~12–16 magnetic local time during geomagnetically active times. In order to find the mechanism that generates these field‐aligned energetic proton populations, we have studied eight such events in detail by using the low‐altitude DMSP, POES satellites, and the NOAA‐LANL satellite at the geosynchronous orbit. The results imply that these energetic ions with field‐aligned PADs probably are accelerated by ionospheric disturbances that are triggered by tail injections. These results provide evidence of another possibly important source of the ring current ions.Key PointsWe have found that about 5% of the time on the dayside, protons with energies of ~30 to 50 keV have strong field‐aligned PADsThe field‐aligned PADs have higher occurrence rates at ~12‐16 MLT during geomagnetically active timesThese energetic field‐aligned ions possibly are accelerated by ionospheric disturbances triggered by tail injectionsPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/153687/1/grl60102_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/153687/2/grl60102.pd

    Application of kernel functions for accurate similarity search in large chemical databases

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    Background Similaritysearch in chemical structure databases is an important problem with many applications in chemical genomics, drug design, and efficient chemical probe screening among others. It is widely believed that structure based methods provide an efficient way to do the query. Recently various graph kernel functions have been designed to capture the intrinsic similarity of graphs. Though successful in constructing accurate predictive and classification models, graph kernel functions can not be applied to large chemical compound database due to the high computational complexity and the difficulties in indexing similarity search for large databases. Results To bridge graph kernel function and similarity search in chemical databases, we applied a novel kernel-based similarity measurement, developed in our team, to measure similarity of graph represented chemicals. In our method, we utilize a hash table to support new graph kernel function definition, efficient storage and fast search. We have applied our method, named G-hash, to large chemical databases. Our results show that the G-hash method achieves state-of-the-art performance for k-nearest neighbor (k-NN) classification. Moreover, the similarity measurement and the index structure is scalable to large chemical databases with smaller indexing size, and faster query processing time as compared to state-of-the-art indexing methods such as Daylight fingerprints, C-tree and GraphGrep. Conclusions Efficient similarity query processing method for large chemical databases is challenging since we need to balance running time efficiency and similarity search accuracy. Our previous similarity search method, G-hash, provides a new way to perform similarity search in chemical databases. Experimental study validates the utility of G-hash in chemical databases

    Control of apico-basal epithelial polarity by the microtubule minus-end-binding protein CAMSAP3 and spectraplakin ACF7

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    The microtubule cytoskeleton regulates cell polarity by spatially organizing membrane trafficking and signaling processes. In epithelial cells, microtubules form parallel arrays aligned along the apico–basal axis, and recent work has demonstrated that the members of CAMSAP/Patronin family control apical tethering of microtubule minus ends. Here, we show that in mammalian intestinal epithelial cells, the spectraplakin ACF7 (also known as MACF1) specifically binds to CAMSAP3 and is required for the apical localization of CAMSAP3-decorated microtubule minus ends. Loss of ACF7 but not of CAMSAP3 or its homolog CAMSAP2 affected the formation of polarized epithelial cysts in three-dimensional cultures. In short-term epithelial polarization assays, knockout of CAMSAP3, but not of CAMSAP2, caused microtubule re-organization into a more radial centrosomal array, redistribution of Rab11-positive (also known as Rab11A) endosomes from the apical cell surface to the pericentrosomal region and inhibition of actin brush border formation at the apical side of the cell. We conclude that ACF7 is an important regulator of apico–basal polarity in mammalian intestinal cells and that a radial centrosome-centered microtubule organization can act as an inhibitor of epithelial polarity

    Rational Design of Temperature-Sensitive Alleles Using Computational Structure Prediction

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    Temperature-sensitive (ts) mutations are mutations that exhibit a mutant phenotype at high or low temperatures and a wild-type phenotype at normal temperature. Temperature-sensitive mutants are valuable tools for geneticists, particularly in the study of essential genes. However, finding ts mutations typically relies on generating and screening many thousands of mutations, which is an expensive and labor-intensive process. Here we describe an in silico method that uses Rosetta and machine learning techniques to predict a highly accurate “top 5” list of ts mutations given the structure of a protein of interest. Rosetta is a protein structure prediction and design code, used here to model and score how proteins accommodate point mutations with side-chain and backbone movements. We show that integrating Rosetta relax-derived features with sequence-based features results in accurate temperature-sensitive mutation predictions

    Heritable Targeted Inactivation of Myostatin Gene in Yellow Catfish (Pelteobagrus fulvidraco) Using Engineered Zinc Finger Nucleases

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    Yellow catfish (Pelteobagrus fulvidraco) is one of the most important freshwater aquaculture species in China. However, its small size and lower meat yield limit its edible value. Myostatin (MSTN) is a negative regulator of mammalian muscle growth. But, the function of Mstn in fish remains elusive. To explore roles of mstn gene in fish growth and create a strain of yellow catfish with high amount of muscle mass, we performed targeted disruption of mstn in yellow catfish using engineered zinc-finger nucleases (ZFNs). Employing zebrafish embryos as a screening system to identify ZFN activity, we obtained one pair of ZFNs that can edit mstn in yellow catfish genome. Using the ZFNs, we successfully obtained two founders (Founder July29-7 and Founder July29-8) carrying mutated mstn gene in their germ cells. The mutated mstn allele inherited from Founder July29-7 was a null allele (mstnnju6) containing a 4 bp insertion, predicted to encode function null Mstn. The mutated mstn inherited from Founder July29-8 was a complex type of mutation (mstnnju7), predicted to encode a protein lacking two amino acids in the N-terminal secretory signal of Mstn. Totally, we obtained 6 mstnnju6/+ and 14 mstnnju7/+ yellow catfish. To our best knowledge, this is the first endogenous gene knockout in aquaculture fish. Our result will help in understanding the roles of mstn gene in fish
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