Timing observations from the Parkes 64-m radio telescope for 165 pulsars between 1990 and 2011 have been searched for period glitches. Data spans for each pulsar ranged between 5.3 and 20.8 yr. From ...the total of 1911 yr of pulsar rotational history, 107 glitches were identified in 36 pulsars. Out of these glitches, 61 have previously been reported whereas 46 are new discoveries. Glitch parameters, both for the previously known and the new glitch detections, were measured by fitting the timing residual data. Observed relative glitch sizes Δνg/ν range between 10−10 and 10−5, where ν = 1/P is the pulse frequency. We confirm that the distribution of Δνg/ν is bimodal with peaks at approximately 10−9 and 10−6. Glitches are mostly observed in pulsars with characteristic ages between 103 and 105 yr, with large glitches mostly occurring in the younger pulsars. Exponential post-glitch recoveries were observed for 27 large glitches in 18 pulsars. The fraction Q of the glitch that recovers exponentially also has a bimodal distribution. Large glitches generally have low Q, typically just a few per cent, but large Q values are observed in both large and small glitches. Observed time constants for exponential recoveries ranged between 10 and 300 d with some tendency for longer time-scales in older pulsars. Shorter time-scale recoveries may exist but were not revealed by our data which typically have observation intervals of 2-4 weeks. For most of the 36 pulsars with observed glitches, there is a persistent linear increase in
(i.e. decrease in the slow-down rate
) in the interglitch interval. Where an exponential recovery is also observed, the effects of this are superimposed on the linear increase in
. In some but not all cases, the slope of the linear recovery changes at the time of a glitch. The
values characterizing the linear changes in
are almost always positive and, after subtracting the magnetospheric component of the braking, are approximately proportional to the ratio of
and the interglitch interval, as predicted by vortex-creep models.
The development of high-performance ultraelastic metals with superb strength, a large elastic strain limit and temperature-insensitive elastic modulus (Elinvar effect) are important for various ...industrial applications, from actuators and medical devices to high-precision instruments
. The elastic strain limit of bulk crystalline metals is usually less than 1 per cent, owing to dislocation easy gliding. Shape memory alloys
-including gum metals
and strain glass alloys
-may attain an elastic strain limit up to several per cent, although this is the result of pseudo-elasticity and is accompanied by large energy dissipation
. Recently, chemically complex alloys, such as 'high-entropy' alloys
, have attracted tremendous research interest owing to their promising properties
. In this work we report on a chemically complex alloy with a large atomic size misfit usually unaffordable in conventional alloys. The alloy exhibits a high elastic strain limit (approximately 2 per cent) and a very low internal friction (less than 2 × 10
) at room temperature. More interestingly, this alloy exhibits an extraordinary Elinvar effect, maintaining near-constant elastic modulus between room temperature and 627 degrees Celsius (900 kelvin), which is, to our knowledge, unmatched by the existing alloys hitherto reported.
The large-scale magnetic field of our Galaxy can be probed in three dimensions using Faraday rotation of pulsar signals. We report on the determination of 223 rotation measures from polarization ...observations of relatively distant southern pulsars made using the Parkes radio telescope. Combined with previously published observations, these data give clear evidence for large-scale counterclockwise fields (viewed from the north Galactic pole) in the spiral arms interior to the Sun and weaker evidence for a counterclockwise field in the Perseus arm. However, in interarm regions, including the solar neighborhood, we present evidence that suggests that large-scale fields are clockwise. We propose that the large-scale Galactic magnetic field has a bisymmetric structure with reversals on the boundaries of the spiral arms. Streaming motions associated with spiral density waves can directly generate such a structure from an initial, inwardly directed radial field. Large-scale fields increase toward the Galactic center, with a mean value of about 2 kG in the solar neighborhood and 4 kG at a galactocentric radius of 3 kpc.
► Land-use change impacts on hydrological processes in the Elbow River watershed, Canada were modeled. ► A cellular automata and MIKE-SHE were implemented within an integrated framework. ► Changes in ...multiple land uses were simulated up to 2031. ► Urbanization increases overland flow and reduces total water supply via the Elbow River. ► This highlights the importance of capturing local land-use changes in hydrological modeling.
The Elbow River in southern Alberta, Canada is the source of the Glenmore reservoir, which provides drinking water to the City of Calgary. Due to the rapid population growth in Calgary, the Elbow River watershed (ERW) that covers about 1238 km
2 has been under considerable pressure for land-use development over the last decade. This study was undertaken to assess the impact of potential land-use changes over the next 20
years on the hydrological processes in ERW by combining a land-use cellular automata (CA) model and the distributed physically-based MIKE-SHE/MIKE-11 hydrological model. The CA model was calibrated using four land-use maps covering the period 1985–2001 and validated against the maps of 2006 and 2010. Simulations of land-use changes were then performed from 2006 to 2031 at a five year interval; land-use based parameters were extracted from the simulated maps and transferred to MIKE-SHE/MIKE-11. MIKE-SHE was calibrated for the period 1985–1990 and validated for the period 2000–2005. The Nash and Sutcliffe coefficients of efficiency calculated between observed and simulated flow data for the calibration and validation periods are 0.56, 0.52, 0.79, and 0.75 based on different hydrometric stations respectively, indicating an acceptable level of performance of the model. Land-use changes analyzed for the period 2001–2031 reveal a 65% increase in built-up areas, 20% in rangeland/parkland, and 1% in agriculture along with a reduction of 28% in deciduous, and 6% in evergreen forest. As a result, the hydrological modeling indicates an increase of 7.3% in overland flow, and a decrease of 1%, 13.2%, and 2.3% in total evapotranspiration, baseflow, and infiltration respectively along with a decrease of the total flow by 4%. These results reveal a potential significant negative impact on the sustainability of ground/surface water supplies and groundwater storages in the future in the watershed in addition to an increased risk of flashy floods. The study also revealed that due to the complex hydrological regime existing in the study area, a comprehensive physically-based method is required to better represent the interaction between groundwater and surface water. The combined CA/MIKE-SHE models appear as a useful tool to assess the impact of land-use changes on the hydrologic cycle and to better understand the connection among the hydrologic components in the Elbow River watershed.
High circulating neutrophil-lymphocyte ratio (NLR) appears to be prognostic in metastatic colorectal cancer (mCRC). We investigated the relationship of NLR with circulating cytokines and molecular ...alterations.
We performed retrospective analyses on multiple cohorts of CRC patients (metastatic untreated (n=166), refractory metastatic (n=161), hepatectomy (n=198), stage 2/3 (n=274), and molecularly screened (n=342)). High NLR (ratio of absolute neutrophil-to-lymphocyte counts in peripheral blood) was defined as NLR>5. Plasma cytokines were evaluated using multiplex-bead assays. Kaplan-Meier estimates, non-parametric correlation analysis, and hierarchical cluster analyses were used.
High NLR was associated with poor prognosis in mCRC (hazard ratio (HR) 1.73; 95% confidence interval (CI):1.03-2.89; P=0.039) independent of known prognostic factors and molecular alterations (KRAS/NRAS/BRAF/PIK3CA/CIMP). High NLR correlated with increased expression of interleukin 6 (IL-6), IL-8, IL-2Rα, hepatocyte growth factor, macrophage-colony stimulating factor, and vascular epidermal growth factor in exploratory (n=39) and validation (n=166) cohorts. Fourteen additional cytokines correlated with high NLR in the validation cohort. All 20 cytokines fell into three major clusters: inflammatory cytokines, angiogenic cytokines, and epidermal growth factor ligands. In mCRC, composite stratification based on NLR-cytokine score provided enhanced prognostic information (HR 2.09; 95% CI: 1.59-2.76; P<0.001) over and above NLR.
High NLR is an independent poor prognostic marker in CRC and correlates with a distinct cytokine profile related to key biological processes involved in carcinogenesis. A composite NLR-cytokine stratification has enhanced prognostic value in mCRC.
•A theoretical framework based on the hierarchically correlated atomic theory of the glassy materials was proposed.•The theoretical framework can be validated by the stress relaxation and creep ...experiments on typical La-based metallic glass.•It provides quantitative insights into the non-elastic deformation mechanisms in metallic glasses.
Due to the structurally disordered arrangement of atoms and deviation from thermodynamic equilibrium, the physical and mechanical properties of metallic glasses can vary with time, temperature and magnitude of strain or stress. The current work provides a theoretical framework based on the hierarchically correlated atomic theory, which allows a quantitative description of the non-elastic deformation in metallic glasses. The defect concentration is adopted as an order parameter, which can evolve with temperature and non-elastic strain owing to correlated atomic movements. Through our hierarchically correlated atomic theory, we derive the characteristic times for local shear events in metallic glasses that entail activation, growth and/or annihilation of flow defects, which however are not accounted for in the previous mean field theories. Finally, we demonstrate that the current theoretical framework can be validated by the stress relaxation and creep experiments on typical La-based metallic glasses, which in turn provides quantitative insights into the non-elastic deformation mechanisms in metallic glasses.
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A large Mg-4.50Zn-1.13Ca (wt%) alloy ingot 350mm in diameter and 1730mm long was successfully fabricated by semi-continuous casting. The microstructures and mechanical properties of the as-cast and ...as-extruded alloys were investigated. The as-cast alloy exhibits uniform chemical composition and microstructure from the centre to the surface of the ingot and mainly consists of α-Mg and Ca2Mg6Zn3. The coarse grains and network-like second phases that are distributed at the grain boundaries result in poor mechanical properties for the as-cast alloy. The mechanical properties of the as-extruded alloys are significantly enhanced. The high yield strengths of the as-extruded alloys mainly result from the fine DRXed grain and the stronger basal texture.
Abstract
We report the observations of periodic nulling in PSR B2111+46 at 1250 MHz with the Five-hundred-meter Aperture Spherical radio Telescope (FAST). The nulling fractions (NF) as well as ...nulling period of this pulsar were calculated. The NF and nulling period are 17% ± 1% and 62.49 ± 0.99
P
1
, respectively, and the periodic nulling shows variations in periodicity with time. The durations of each consecutive burst and nulling were investigated, which show that the power-law distribution and the indices are −1.11 ± 0.04 and −2.08 ± 0.23. In the observed frequency band, the width of the profile is narrowed with the increase in frequency, and the degree of polarization has no obvious trend with the increase in frequency. We discovered a weak emission component in front of the leading component of this triple-type profile pulsar that was not observed in other bands and by other telescopes. With the fitting of rotation vector model, we obtained that the angles of the magnetic inclination
α
and the line of sight
ζ
are ∼13.°0 and ∼11.°6, respectively. The high-sensitivity observation of FAST improves our understanding of the emission of this pulsar.
The effects of the warm parameters (the strain rate and forming temperature) on the deformation behavior and microstructure in 2205 duplex stainless steels (DSS) was studied. The hot deformation ...behavior of 2205 DSS was investigated through hot tensile and hot compression testing on a Gleeble-1500 thermal-mechanical simulator within the temperature range of 1023–1623
K, in order to determine their reduction of area, resistance to deformation, deformability, and microstructure. The experimental results show that the hot deformation curves of the test steel has a high temperature brittlement region at temperatures higher than 1523
K, and the optimum hot ductility region is in the temperature range of 1423–1523
K. The microstructure of the steel obtained after hot deformation is much finer compared with the as-cast microstructure of the steel. It was found that dynamic recovery only occurs within the γ-phase during hot deformation, but the δ phase undergoes dynamic recrystallization. Small secondary γ′ phase islands are precipitated on the δ matrix, as demonstrated by TEM analysis, which can markedly promote hot ductility behavior.
A commercial scale Mg-7Gd-2Y–1Zn-0.5Zr alloy extrusion rod with synergetic high yield strength of 350 MPa and fracture toughness KIC of 22.4 MPa m1/2 was fabricated by direct-chill casting, hot ...extrusion and subsequent aging treatment at 200 °C for 108 h. The microstructures and mechanical properties of the as-extruded and peak-aged alloys were investigated, and the fracture toughness and fracture mechanisms before and after aging treatment were also analyzed. The results showed that the as-extruded alloy consisted of long period stacking ordered (LPSO) phase and bimodal matrix microstructure composed of fine dynamic recrystallized (DRXed) grains and coarse deformed grains. Microstructural analysis near fracture surfaces indicted that twinning was activated in the coarse deformed grains during fracture toughness test, which may be conducive to the improvement of the fracture toughness of the alloys. The lamellar-shaped LPSO phases enhanced the fracture toughness since the formation of secondary cracks parallel to the lamellar LPSO can cause significant energy dissipation and deflection of main crack. The micro-cracks were initiated and propagated in the bulk LPSO phases, which may deteriorate the fracture toughness. Large amount of nano β' phase precipitated in the T5 peak-aged alloy significantly improved the strength of the alloy. Fractography analysis indicated that fracture mechanism changed from ductile fracture of the as-extruded alloy to quasi-cleavage fracture of the peak-aged alloy. The precipitation of β' would suppress twin growth and induce the microcracks initiated at the DRXed grain boundaries and in the deformed grains, which led to slight decrease of KIC.
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