In this work, time-resolved particle image velocimetry is used for indoor velocity determination of cross-ventilation flow sheltered by urban-like arrays, to elucidate the instantaneous and ...statistical characteristics of the velocity fields. Combinations of two opening positions relative to the main stream flow and two surrounding array types are considered, yielding four cross-ventilation flow cases for comparison. For the streamwise window condition, the instantaneous velocity distributions differ significantly according to the outdoor block arrangement. Intermittency of the flow introduction through the windward opening and the indoor flow distributions are also confirmed based on temporal variation of the velocities. These differences in flow distribution are statistically correct according to the temporally averaged flow distributions. For the lateral window condition, instantaneous flow introduction is found to occur intermittently and alternately through each opening. Moreover, the flow introduction angle differs according to the outdoor arrangement, for both the instantaneous and mean flow distributions, indicating the importance of the surrounding-block sheltering effects on the indoor flow distributions. In addition to this elucidation of the indoor flow characteristics, the datasets obtained in this work are valuable for validating future numerical analyses of the cross-ventilation flow of a generic block under sheltered conditions.
•Cross-ventilation flows under sheltered conditions were measured using time-resolved PIV.•Instantaneous indoor flow exhibits considerable intermittency.•The mean indoor flow varies significantly with the surrounding block arrangement.•The cross-ventilation flow statistics also vary clearly with the block arrangement.
We have investigated the atomic structure of superconducting Ca-intercalated bilayer graphene on a SiC(0001) substrate using total-reflection high-energy positron diffraction. By comparing the ...experimental rocking-curves with ones calculated for various structural models using a full-dynamical theory, we have found that Ca atoms are intercalated in the graphene-buffer interlayer, rather than between the two graphene layers. From transport measurements, the superconducting transition was observed to be at Tconset = 4 K for this structure. This study is the first to clearly identify the relation between the atomic arrangement and superconductivity in Ca-intercalated bilayer graphene.
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Measuring some 2400 km in length, the Himalaya accommodate millions of people in northern India and Pakistan, Nepal, Bhutan, and parts of other Asian nations. Every year, especially during monsoon ...rains, landslides and related natural events in these mountains cause tremendous damage to lives, property, infrastructure, and environment. In the context of the Himalaya, however, the rainfall thresholds for landslide initiation are not well understood. This paper describes regional aspects of rainfall thresholds for landslides in the Himalaya. Some 677 landslides occurring from 1951 to 2006 were studied to analyze rainfall thresholds. Out of the 677 landslides, however, only 193 associated with rainfall data were analyzed to yield a threshold relationship between rainfall intensity, rainfall duration, and landslide initiation. The threshold relationship fitted to the lower boundary of the field defined by landslide-triggering rainfall events is
I
=
73.90
D
−
0.79
(
I
=
rainfall intensity in mm h
−
1
and
D
=
duration in hours), revealing that when the daily precipitation exceeds 144 mm, the risk of landslides on Himalayan mountain slopes is high. Normalized rainfall intensity–duration relationships and landslide initiation thresholds were established from the data after normalizing rainfall-intensity data with respect to mean annual precipitation (
MAP) as an index in which
N
I
=
1.10
D
−
0.59
(
N
I
=
normalized intensity in h
−
1
). Finally, the role of antecedent rainfall in causing landslides was also investigated by considering daily rainfall during failure and the cumulative rainfall to discover at what point antecedent rainfall plays an important role in Himalayan landslide processes. Rainfall thresholds presented in this paper are generalized so they can be used in landslide warning systems in the Nepal Himalaya.
Abstract
Two-dimensional materials constitute a promising platform for developing nanoscale devices and systems. Their physical properties can be very different from those of the corresponding ...three-dimensional materials because of extreme quantum confinement and dimensional reduction. Here we report a study of TiTe
2
from the single-layer to the bulk limit. Using angle-resolved photoemission spectroscopy and scanning tunneling microscopy and spectroscopy, we observed the emergence of a (2 × 2) charge density wave order in single-layer TiTe
2
with a transition temperature of 92 ± 3 K. Also observed was a pseudogap of about 28 meV at the Fermi level at 4.2 K. Surprisingly, no charge density wave transitions were observed in two-layer and multi-layer TiTe
2
, despite the quasi-two-dimensional nature of the material in the bulk. The unique charge density wave phenomenon in the single layer raises intriguing questions that challenge the prevailing thinking about the mechanisms of charge density wave formation.
The AKARI IRC all-sky survey provided more than twenty thousand thermal infrared observations of over five thousand asteroids. Diameters and albedos were obtained by fitting an empirically calibrated ...version of the standard thermal model to these data. After the publication of the flux catalogue in October 2016, our aim here is to present the AKARI IRC all-sky survey data and discuss valuable scientific applications in the field of small body physical properties studies. As an example, we update the catalogue of asteroid diameters and albedos based on AKARI using the near-Earth asteroid thermal model (NEATM). We fit the NEATM to derive asteroid diameters and, whenever possible, infrared beaming parameters. We fit groups of observations taken for the same object at different epochs of the survey separately, so we compute more than one diameter for approximately half of the catalogue. We obtained a total of 8097 diameters and albedos for 5170 asteroids, and we fitted the beaming parameter for almost two thousand of them. When it was not possible to fit the beaming parameter, we used a straight line fit to our sample’s beaming parameter-versus-phase angle plot to set the default value for each fit individually instead of using a single average value. Our diameters agree with stellar-occultation-based diameters well within the accuracy expected for the model. They also match the previous AKARI-based catalogue at phase angles lower than 50°, but we find a systematic deviation at higher phase angles, at which near-Earth and Mars-crossing asteroids were observed. The AKARI IRC All-sky survey is an essential source of information about asteroids, especially the large ones, since, it provides observations at different observation geometries, rotational coverages and aspect angles. For example, by comparing in more detail a few asteroids for which dimensions were derived from occultations, we discuss how the multiple observations per object may already provide three-dimensional information about elongated objects even based on an idealised model like the NEATM. Finally, we enumerate additional expected applications for more complex models, especially in combination with other catalogues.
Context.
The Hayabusa2 spacecraft launched by Japan Aerospace Exploration Agency has been conducting observations of the asteroid (162173) Ryugu since June 2018. The Telescopic Optical Navigation ...Camera (ONC-T) onboard Hayabusa2 has obtained thousands of images under a variety of illumination and viewing conditions.
Aims.
Our objective is to examine and validate the camera calibration, derive a photometric correction for creating global albedo maps, and to interpret the photometric modeling results to characterize the surface of Ryugu.
Methods.
We observed (162173) Ryugu with the Gemini-South telescope, and combined these measurements with other published ground-based observations of the asteroid. The ground-based observations were compared with the data obtained by ONC-T in order to validate the radiometric calibration mutually. We used a combination of the Hapke disk-integrated and disk-resolved model equations to simultaneously analyze the combined ground- and spacecraft-based data.
Results.
The average spectrum of Ryugu was classified as Cb-type following the SMASSII taxonomy and C/F-type following the Tholen taxonomy based on spacecraft observations. We derived Hapke model parameters for all seven color filters, which allowed us to photometrically correct images to within an error of <10% for ~80% of the image pixels used in the modeling effort. Using this model, we derived a geometric albedo of 4.0 ± 0.5% (
v
band) for Ryugu. The average reflectance factor at the standard illumination condition was 1.87 ± 0.14% in the
v
band. Moreover we measured a phase reddening of (2.0 ± 0.7) × 10
−3
μ
m
−1
deg
−1
for Ryugu, similar to that observed for the asteroid (101955) Bennu.
Conclusions.
The global color map showed that the general trend was for darker regions to also be redder regions, however there were some distinct exceptions to this trend. For example, Otohime Saxum was bright and red while Kibidango crater was dark and blue. The darkness and flatness of Ryugu’s reflectance might be caused by a high abundance of organic materials.
Summary
The activation of nuclear factor‐kappa B (NF‐κB) in vascular endothelial cells may be involved in vascular pathogeneses such as vasculitis or atherosclerosis. Recently, it has been reported ...that some amino acids exhibit anti‐inflammatory effects. We investigated the inhibitory effects of a panel of amino acids on cytokine production or expression of adhesion molecules that are involved in inflammatory diseases in various cell types. The activation of NF‐κB was determined in human coronary arterial endothelial cells (HCAECs) because NF‐κB modulates the production of many cytokines and the expression of adhesion molecules. We examined the inhibitory effects of the amino acids cysteine, histidine and glycine on the induction of NF‐κB activation, expression of CD62E (E‐selectin) and the production of interleukin (IL)‐6 in HCAECs stimulated with tumour necrosis factor (TNF)‐α. Cysteine, histidine and glycine significantly reduced NF‐κB activation and inhibitor κBα (IκBα) degradation in HCAECs stimulated with TNF‐α. Additionally, all the amino acids inhibited the expression of E‐selectin and the production of IL‐6 in HCAECs, and the effects of cysteine were the most significant. Our results show that glycine, histidine and cysteine can inhibit NF‐κB activation, IκBα degradation, CD62E expression and IL‐6 production in HCAECs, suggesting that these amino acids may exhibit anti‐inflammatory effects during endothelial inflammation.
Context. The JAXA Hayabusa2 mission will perform the first ever sample return from a primitive asteroid. The target near-Earth asteroid (162173) Ryugu will be reached in mid-2018 and its samples will ...be returned to the Earth by the end of 2020. Aims. We want to improve the current knowledge of the compositional and rotational properties of Ryugu, which are still presenting some uncertainties that might affect the mission operations and scientific return. Methods. We acquired high-quality photometric time-series data with the FORS2 instrument at the Very Large Telescope of the European Southern Observatory (ESO-VLT, Chile). We also acquired four FORS2 visible spectra and three X-shooter spectra in the 0.35−2.15 μm range, at different rotational phases. Results. We obtained the currently highest-quality visual light-curve of Ryugu. A best solution of ~7.63 h is found for the rotational period, while a short-period solution (i.e., P ≈ 3.8 h) is ruled out by the clearly non-symmetric light-curve. The obtained spectra are generally similar and featureless, but present a drop-off of the reflectance at <0.45 μm, suggesting the presence of aqueously altered minerals on Ryugu. The best meteorite analogs for Ryugu are represented by thermally altered CM carbonaceous chondrites. Conclusions. Our new photometric data help to refine the target reference model used by the Hayabusa2 team for the mission preparation and implementation, improving our knowledge of Ryugu’s spin properties. Our new spectra constrain the compositional and geological context of the Ryugu’s surface in order to prepare the planning of mission observations and support the working group for the selection of possible landing and sampling sites.
Magnesium alloys are attracting engineers for their practical application to structural components. Here fatigue properties, which is essential for structural use, have been examined on extruded AZ31 ...bar under uniaxial cyclic loading by both strain and stress controlled conditions. Adding fatigue tests with mean stresses under stress controlling conditions, fatigue life evaluation method has been discussed along with the analysis of cyclic stress–strain behavior. The specimen is easy to yield in compression by twinning. This leads to the asymmetric hysteresis curves. It also tends to deform quasi-elastically during unloading from compression; this makes the plastic strain amplitude smaller to the maximum one in the hysteresis curve. These asymmetric features fairly disappear at half-life in the stress controlled tests. The fatigue lives and deformation characteristics can be expressed nicely by Manson–Coffin type equation. On the contrary, the strain controlled tests retain the asymmetry till the end and produce tensile mean stresses. The fatigue lives are unsuccessfully evaluated by the above equation. Various mean stress correction models for cubic metals are not operative in magnesium alloys. A new model has been devised adding a correction term of −
σ
m/2
E to the above mentioned Manson–Coffin type equation. Strain controlled test, as it retains pyriform shape till the end, could be evaluated more accurately with the maximum plastic strain amplitude in the hysteresis curve.
Pancreatic cancer has a poor prognosis because of its high refractoriness to chemotherapy and tumour recurrence, and these properties have been attributed to cancer stem cells (CSCs). MicroRNA ...(miRNA) regulates various molecular mechanisms of cancer progression associated with CSCs. This study aimed to identify the candidate miRNA and to characterise the clinical significance.
We established gemcitabine-resistant Panc1 cells, and induced CSC-like properties through sphere formation. Candidate miRNAs were selected through microarray analysis. The overexpression and knockdown experiments were performed by evaluating the in vitro cell growth and in vivo tumourigenicity. The expression was studied in 24 pancreatic cancer samples after laser captured microdissection and by immunohistochemical staining.
The in vitro drug sensitivity of pancreatic cancer cells was altered according to the miR-1246 expression via CCNG2. In vivo, we found that miR-1246 could increase tumour-initiating potential and induced drug resistance. A high expression level of miR-1246 was correlated with a worse prognosis and CCNG2 expression was significantly lower in those patients.
miR-1246 expression was associated with chemoresistance and CSC-like properties via CCNG2, and could predict worse prognosis in pancreatic cancer patients.
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