Graphene oxide (GO) and polyhedral oligomeric silsesquioxane (POSS) grafted carbon fiber (CF) was demonstrated to reinforce the mechanical properties of fiber composites. Such a fiber composite was ...prepared by grafting POSS onto the CF surface using GO as the linkage. The presence of GO linkage and POSS could significantly enhance both the area and wettability of fiber surface, leading to an increase in the interfacial strength between fibers and resin. Compared with the desized CF composites, the grafted CF composites fabricated by compression molding method exhibited 53.05% enhancement in the interlaminar shear strength. The changed surface morphology, surface composition and surface energy were supposed to be related with the interfacial performance of unidirectional composites, as revealed by scanning electron microscopy, atomic force microscope, dynamic contact angle test and X-ray photoelectron microscopy charaterizations.
On 17 August 2017, the Advanced LIGO and Virgo detectors observed the gravitational-wave event GW170817-a strong signal from the merger of a binary neutron-star system. Less than two seconds after ...the merger, a γ-ray burst (GRB 170817A) was detected within a region of the sky consistent with the LIGO-Virgo-derived location of the gravitational-wave source. This sky region was subsequently observed by optical astronomy facilities, resulting in the identification of an optical transient signal within about ten arcseconds of the galaxy NGC 4993. This detection of GW170817 in both gravitational waves and electromagnetic waves represents the first 'multi-messenger' astronomical observation. Such observations enable GW170817 to be used as a 'standard siren' (meaning that the absolute distance to the source can be determined directly from the gravitational-wave measurements) to measure the Hubble constant. This quantity represents the local expansion rate of the Universe, sets the overall scale of the Universe and is of fundamental importance to cosmology. Here we report a measurement of the Hubble constant that combines the distance to the source inferred purely from the gravitational-wave signal with the recession velocity inferred from measurements of the redshift using the electromagnetic data. In contrast to previous measurements, ours does not require the use of a cosmic 'distance ladder': the gravitational-wave analysis can be used to estimate the luminosity distance out to cosmological scales directly, without the use of intermediate astronomical distance measurements. We determine the Hubble constant to be about 70 kilometres per second per megaparsec. This value is consistent with existing measurements, while being completely independent of them. Additional standard siren measurements from future gravitational-wave sources will enable the Hubble constant to be constrained to high precision.
In this paper, we test whether time periods with hot proton temperature anisotropy are associated with electromagnetic ion cyclotron (EMIC) waves and whether the plasma conditions during the observed ...waves satisfy the linear theory threshold condition. We identify 865 events observed by the Composition Distribution Function instrument onboard Cluster spacecraft 4 during 1 January 2001 to 1 January 2011 that exhibit a positive temperature anisotropy (Ahp = T⊥ h/T∥ h − 1) in the 10–40 keV protons. The events occur over an L range from 4 to 10 in all magnetic local times and at magnetic latitudes (MLATs) within ±50°. Of these hot proton temperature anisotropy (HPTA) events, only 68 events have electromagnetic ion cyclotron (EMIC) waves. In these 68 HPTA events, for those at 3.8<L ≤ 5 and |MLAT| ≤ 10°, the EMIC waves with powers >1.0 nT2/Hz mainly appear in the region with fEMIC/fH,eq < 0.8. Two stop bands are present, one near the region with fEMIC/fH,eq ≈ 0.33, the other in the region with 0.8 < fEMIC/fH,eq < 0.9. Most of the EMIC waves in the He, H, and >H bands satisfy Ahp/(Ahp + 1) > fEMIC/fH,lo, Ahp/(Ahp + 1) > 0.45 × fEMIC/fH,lo, and Ahp/(Ahp + 1) < 0.45 × fEMIC/fH,lo. fEMIC, fH,eq, and fH,lo are the EMIC wave frequency, the magnetic equatorial, and the local proton gyrofrequencies. We also find that the EMIC waves predominantly occur with Ahp > 0.25. By testing a threshold equation for the EMIC instability based on linear theory, we find that for EMIC waves with |MLAT| ≤ 10° in the He, H, and >H bands, the percentages that satisfy the predicted conditions for wave growth by the threshold equation are 15.2%, 24.6%, and 25.6%. For the EMIC waves with |MLAT| > 10° the percentages that satisfy the wave growth predicted conditions are only 2.8%, 2.6%, and 0.0%. Finally, possible reasons for the low forecast accuracies of EMIC waves are suggested.
Key Points
We do the statistical analysis of EMIC waves from a 10 year Cluster observation
We test the A_hp versus EMIC wave frequency formula of Kennel and Petschek (1966)
We test the linear theory derived by Blum et al. (2009)
Abstract Background Gastric cancer is one of most common malignancies in the world. Currently the prognostic prediction is entirely based on the TNM staging system. In this study, we evaluated ...whether metastatic lymph node ratio (rN) at the time of surgery would improve the prognostic prediction in conjunction with the TNM staging system. Methods This retrospective study includes 745 patients, who had been referred for surgery due to gastric cancer between 1995 and 2007 and had at least 15 lymph nodes examined at the time of surgery without preoperative treatment. Clinicopathologic features and overall survival were analyzed using univariate and multivariate modes to identify the risk factors for overall survival. Results Median overall survival of all patients analyzed is 57.8 months and 5-year overall survival is 49.5%. Tumor site, macroscopic type, pTNM stage, and rN stage are identified as independent prognostic factors. Increased positive lymph node ratio correlates with shorter survival in all patients and in each T and N stage. In stage III gastric cancer patients, rN stage shows additional prognostic value on overall survival ( p < 0.001). Conclusions rN stage is a simple and promising prognostic factor of gastric cancer after surgery in addition to the TNM stage system especially in stage III patients. But the independent prognostic value of rN stage in stage I, II and IV gastric cancer is yet to be determined.
Most motion correction methods work by aligning a set of volumes together, or to a volume that represents a reference location. These are based on an implicit assumption that the subject remains ...motionless during the several seconds it takes to acquire all slices in a volume, and that any movement occurs in the brief moment between acquiring the last slice of one volume and the first slice of the next. This is clearly an approximation that can be more or less good depending on how long it takes to acquire one volume and in how rapidly the subject moves. In this paper we present a method that increases the temporal resolution of the motion correction by modelling movement as a piecewise continous function over time. This intra-volume movement correction is implemented within a previously presented framework that simultaneously estimates distortions, movement and movement-induced signal dropout. We validate the method on highly realistic simulated data containing all of these effects. It is demonstrated that we can estimate the true movement with high accuracy, and that scalar parameters derived from the data, such as fractional anisotropy, are estimated with greater fidelity when data has been corrected for intra-volume movement. Importantly, we also show that the difference in fidelity between data affected by different amounts of movement is much reduced when taking intra-volume movement into account. Additional validation was performed on data from a healthy volunteer scanned when lying still and when performing deliberate movements. We show an increased correspondence between the “still” and the “movement” data when the latter is corrected for intra-volume movement. Finally we demonstrate a big reduction in the telltale signs of intra-volume movement in data acquired on elderly subjects.
•We introduce a method to correct for intra-volume movement into an existing framework for movement and distortion correction.•It has been validated on realistic simulated data and on experimental data with deliberate movement.•The results indicate that one can reliably reverse the adverse effects of intra-volume movement.
The western Pacific subtropical high (WPSH) is closely related to Asian climate. Previous examination of changes in the WPSH found a westward extension since the late 1970s, which has contributed to ...the interdecadal transition of East Asian climate. The reason for the westward extension is unknown, however. The present study suggests that this significant change of WPSH is partly due to the atmosphere’s response to the observed Indian Ocean–western Pacific (IWP) warming. Coordinated by a European Union’s Sixth Framework Programme, Understanding the Dynamics of the Coupled Climate System (DYNAMITE), five AGCMs were forced by identical idealized sea surface temperature patterns representative of the IWP warming and cooling. The results of these numerical experiments suggest that the negative heating in the central and eastern tropical Pacific and increased convective heating in the equatorial Indian Ocean/Maritime Continent associated with IWP warming are in favor of the westward extension of WPSH. The SST changes in IWP influences the Walker circulation, with a subsequent reduction of convections in the tropical central and eastern Pacific, which then forces an ENSO/Gill-type response that modulates the WPSH. The monsoon diabatic heating mechanism proposed by Rodwell and Hoskins plays a secondary reinforcing role in the westward extension of WPSH. The low-level equatorial flank of WPSH is interpreted as a Kelvin response to monsoon condensational heating, while the intensified poleward flow along the western flank of WPSH is in accord with Sverdrup vorticity balance. The IWP warming has led to an expansion of the South Asian high in the upper troposphere, as seen in the reanalysis.
Celotno besedilo
Dostopno za:
BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
This paper is a statistical survey of polar cap patches in relation to solar and geomagnetic activity. Ten thousand six hundred eighty‐eight patches have been identified from in situ plasma ...observations of the Defense Meteorological Satellite Program F16 satellite for 14 years (2005–2018). These patches are divided into two groups: (a) cold patches, which consist of dense but cold plasma; and (b) hot patches, which consist of dense but hot plasma. The statistical results indicate that (a) the occurrence of cold patches is clearly dependent on solar and geomagnetic activity, but hot patches don not show such dependence; (b) both cold and hot patches preferably appear in the winter season; (c) the spatial size of both cold and hot patches decreases (increases) with solar (geomagnetic) activity; (d) the spatial size of cold patches appears larger than that of hot patches under similar solar and geomagnetic activity.
Plain Language Summary
Polar cap patches are localized regions of enhanced plasma density in the polar ionosphere. They are associated with strong electron density gradients resulting in non‐negligible ionospheric scintillations for satellite communication and navigation systems. To characterize polar cap patches and investigate their statistical dependence on solar and geomagnetic activity, 10,688 patches have been identified from 14 years of in situ Defense Meteorological Satellite Program satellite plasma observations. These patches have been divided into cold and hot patches. We find that cold patches occur more frequently during solar maximum years. The spatial size of cold and hot patches decreases with solar activity (increases with geomagnetic activity). Furthermore, the spatial size of cold patches is larger than that of hot patches under similar solar and geomagnetic activity.
Key Points
The occurrence of cold patches is clearly dependent on solar and geomagnetic activity, while hot patches do not show such dependence
In NH winter, the spatial size of both cold and hot patches decreases (increases) with solar (geomagnetic) activity
In NH winter, the spatial size of cold patches appears larger than that of hot patches under similar solar and geomagnetic activity
Mutations in the genes encoding isocitrate dehydrogenase, IDH1 and IDH2, have been reported in gliomas, myeloid leukemias, chondrosarcomas and thyroid cancer. We discovered IDH1 and IDH2 mutations in ...34 of 326 (10%) intrahepatic cholangiocarcinomas. Tumor with mutations in IDH1 or IDH2 had lower 5-hydroxymethylcytosine and higher 5-methylcytosine levels, as well as increased dimethylation of histone H3 lysine 79 (H3K79). Mutations in IDH1 or IDH2 were associated with longer overall survival (P=0.028) and were independently associated with a longer time to tumor recurrence after intrahepatic cholangiocarcinoma resection in multivariate analysis (P=0.021). IDH1 and IDH2 mutations were significantly associated with increased levels of p53 in intrahepatic cholangiocarcinomas, but no mutations in the p53 gene were found, suggesting that mutations in IDH1 and IDH2 may cause a stress that leads to p53 activation. We identified 2309 genes that were significantly hypermethylated in 19 cholangiocarcinomas with mutations in IDH1 or IDH2, compared with cholangiocarcinomas without these mutations. Hypermethylated CpG sites were significantly enriched in CpG shores and upstream of transcription start sites, suggesting a global regulation of transcriptional potential. Half of the hypermethylated genes overlapped with DNA hypermethylation in IDH1-mutant gliobastomas, suggesting the existence of a common set of genes whose expression may be affected by mutations in IDH1 or IDH2 in different types of tumors.
The radiation-based sterile insect technique (SIT) has successfully suppressed field populations of several insect pest species, but its effect on mosquito vector control has been limited. The ...related incompatible insect technique (IIT)-which uses sterilization caused by the maternally inherited endosymbiotic bacteria Wolbachia-is a promising alternative, but can be undermined by accidental release of females infected with the same Wolbachia strain as the released males. Here we show that combining incompatible and sterile insect techniques (IIT-SIT) enables near elimination of field populations of the world's most invasive mosquito species, Aedes albopictus. Millions of factory-reared adult males with an artificial triple-Wolbachia infection were released, with prior pupal irradiation of the released mosquitoes to prevent unintentionally released triply infected females from successfully reproducing in the field. This successful field trial demonstrates the feasibility of area-wide application of combined IIT-SIT for mosquito vector control.
We present the results of a search for rapidly evolving transients in the Dark Energy Survey Supernova Programme. These events are characterized by fast light-curve evolution (rise to peak in ≲10 d ...and exponential decline in ≲30 d after peak). We discovered 72 events, including 37 transients with a spectroscopic redshift from host galaxy spectral features. The 37 events increase the total number of rapid optical transients by more than a factor of two. They are found at a wide range of redshifts (0.05 < z < 1.56) and peak brightnesses (-15.75 > Mg > -22.25). The multiband photometry is well fit by a blackbody up to few weeks after peak. The events appear to be hot (T ≈ 10 000–30 000 K) and large (R ≈ 1014 - 2 × 1015 cm) at peak, and generally expand and cool in time, though some events show evidence for a receding photosphere with roughly constant temperature. Spectra taken around peak are dominated by a blue featureless continuum consistent with hot, optically thick ejecta. We compare our events with a previously suggested physical scenario involving shock breakout in an optically thick wind surrounding a core-collapse supernova, we conclude that current models for such a scenario might need an additional power source to describe the exponential decline. We find that these transients tend to favour star-forming host galaxies, which could be consistent with a core-collapse origin. However, more detailed modelling of the light curves is necessary to determine their physical origin.
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