bluuebunny/crossref_metadata_2025_split huggingface dataset:
Experimental Study on Gravitational and Atmospheric Effects on Crater Size Formed by Low‐Velocity Impacts Into Granular Media
Authors: Kiuchi M. , Nakamura A. M. , Wada K. 
Published: March 2019

AbstractCollisions are ubiquitous phenomena on the surface of solar system objects. When secondary craters form on the surface of small bodies, such as asteroids and comets, the impactors have very low velocities of several meters per second or less. These secondary collisions can affect the surface topography of small bodies. Therefore, it is important to investigate low‐velocity impacts on a target simulating regolith to understand the effects of secondary collisions on the surface of small bodies. We conducted impact experiments into granular materials with a velocity range of 1 to 4.6 m/s, under a gravity range of 0.20 to 1 G, to investigate the effects of gravity on crater diameter. The gravitational dependence obtained under the reduced ambient pressure almost agreed with those obtained for high‐velocity impacts in previous studies. Gravitational dependences obtained under the standard atmospheric condition roughly agreed with the dependence obtained under the reduced pressure condition when a term of nondimensional atmospheric pressure was added to the scaling relationship. It was found that the crater‐size scaling law obtained for high‐velocity impacts could be applied to low‐velocity impacts of several meters per second under the reduced ambient pressure when the density ratio of the projectile to the target was close to unity. Finally, we applied the experimental results to estimate the diameters of secondary craters on asteroid 25143 Itokawa and compared the diameters with the dimple topography on Itokawa. The results support the hypothesis that dimples are formed by low‐velocity impacts of meter‐sized boulders.
Enhanced Identification of Snow Melt and Refreeze Events From Passive Microwave Brightness Temperature Using Air Temperature
Authors: Tuttle Samuel E. , Jacobs Jennifer M. 
Published: March 2019

AbstractSnow melt and refreeze events are important determinants of spring runoff timing, and snowpack stratigraphy and metamorphism. Previous studies have established the utility of differences between twice‐daily passive microwave brightness temperature (Tb) observations, called the diurnal amplitude variation (DAV), for identifying snow melt and refreeze. Liquid water in snow leads to a large increase in microwave emissivity compared to a completely frozen snowpack, so phase changes from nighttime freezing and daytime melting result in high DAV values. However, the physical temperature of the land surface also contributes to brightness temperature, independent of the phase of water. Thus, it is important to account for physical temperature change when using Tb differences to detect snow melt and refreeze. Here, we use near‐surface air temperature (Ta) to approximate the physical temperature of the land surface and compare diurnal Tb changes (ΔTb) from the Advanced Microwave Scanning Radiometer for the Earth Observing System satellite instrument to coincident Ta changes. We find that an approximately linear relationship exists between ΔTb and ΔTa for frozen snow and fit this relationship using modal linear regression. Melt and refreeze events are identified as large positive and negative excursions from the regression line, respectively. We demonstrate the method in the Northern Great Plains, USA, and evaluate it using ground‐based data from Senator Beck Basin Study Area, Colorado, USA. Melt and refreeze events identified from satellite observations mostly occur after the annual peak snow accumulation and are consistent with snow temperature and snowpack energy balance observations at Senator Beck Basin.
Typical Characteristics of Whistler Mode Waves Categorized by Their Spectral Properties Using Van Allen Probes Observations
Authors: Teng S. , Tao X. , Li W. 
Published: March 2019

AbstractProperties of banded, no‐gap, lower band only, and upper band only whistler mode waves (0.1–0.8fce) outside the plasmasphere are investigated using Van Allen Probes data. Our analysis shows that no‐gap whistler waves have higher occurrence rate at morning side and dayside, while banded and lower band only waves have higher occurrence rate between midnight and dawn. We also find that the occurrence rate of no‐gap whistler waves peaks at magnetic latitude |MLAT|∼8–10°, while banded waves have higher occurrence rate near the equator for
°. The wave normal angle distributions of these four groups of waves are similar to previous results. The distinct local time and latitudinal distribution of no‐gap and banded whistler mode waves is critical to further understand the formation mechanism of the power minimum at half electron gyrofrequency.
Sex-dependent behavioral deficits and neuropathology in a maternal immune activation model of autism
Authors: Haida Obelia , Al Sagheer Tareq , Balbous Anais , Francheteau Maureen , Matas Emmanuel , Soria Federico , Fernagut Pierre Olivier , Jaber Mohamed 
Published: March 2019

AbstractInfections during gestation and the consequent maternal immune activation (MIA) increase the risk of developing neuropsychiatric disorders in infants and throughout life, including autism spectrum disorders (ASD). ASD is a neurodevelopmental disorder that affects three times more males than females and is mainly characterized by deficits in social communication and restricted interests. Consistent findings also indicate that ASD patients suffer from movement disorders, although these symptoms are not yet considered as diagnosis criteria. Here we used the double-stranded RNA analog polyinosinic:polycytidylic acid (poly I:C) MIA animal model of ASD in mice and explored its effects in males and females on social and motor behavior. We then investigated brain areas implicated in controlling and coordinating movements, namely the nigro-striatal pathway, motor cortex and cerebellum. We show that male mice are more affected by this treatment than females as they show reduced social interactions as well as motor development and coordination deficits. Reduced numbers of Purkinje cells in the cerebellum was found more widespread and within distinct lobules in males than in females. Moreover, a reduced number of neurons was found in the motor cortex of males only. These results suggest that females are better protected against developmental insults leading to ASD symptoms in mice. They also point to brain areas that may be targeted to better manage social and motor consequences of ASD.
ECRG4 acts as a tumor suppressor gene frequently hypermethylated in human breast cancer
Authors: Tang Gao-Yan , Tang Guo-Jun , Yin Lu , Chao Chen , Zhou Ren , Ren Guo-Ping , Chen Jia-Yu , Zhang Wei 
Published: March 2019

Abstract
Human breast cancer is a malignant form of tumor with a relatively high mortality rate. Although esophageal cancer-related gene 4 (ECRG4) is thought to be a possible potent tumor suppressor gene that acts to suppress breast cancer, its precise role in this disease is not understood. Herein, we assess the correlation between ECRG4 expression and DNA methylation, probing the potential epigenetic regulation of ECRG4 in breast cancer. We analyzed ECRG4 promoter methylation via methylation-specific PCR (MSPCR), bisulfite sequencing, and a promoter reporter assay in human breast cancer cell lines and samples. Gene expression was assessed by quantitative real-time PCR (qPCR), while protein levels were assessed by Western blotting. CCK8 assays were used to quantify cell growth; Esophageal cancer-related gene 4 wound healing assays were used to assess cellular migration, while flow cytometry was used to assess apoptosis and cell cycle progression. Apoptosome formation was validated via CO-IP and Western blotting. We found that human breast cancer samples exhibited increased methylation of the ECRG4 promoter and decreased ECRG4 expression. Remarkably, the down-regulation of ECRG4 was highly associated with promoter methylation, and its expression could be re-activated via 5-aza-2′-deoxycytidine treatment to induce demethylation. ECRG4 overexpression impaired breast cancer cell proliferation and migration, and led to G0/G1 cell cycle phase arrest. Moreover, ECRG4 induced the formation of the Cytc/Apaf-1/caspase-9 apoptosome and promoted breast cancer cell apoptosis. ECRG4 is silenced in human breast cancer cells and cell lines, likely owing to promoter hypermethylation. ECRG4 may act as a tumor suppressor, inhibiting proliferation and migration, inducing G0/G1 phase arrest and apoptosis via the mitochondrial apoptotic pathway.
Hydrothermal synthesis of 3D hierarchical flower‐like CuGaO2 with high surface area for dye‐sensitised solar cell
Authors: Ursu Daniel , Vajda Melinda , Miclau Marinela 
Published: March 2019

CuGaO2 has been receiving much attention due to its potential as photocathode instead of NiO for p‐type dye sensitised solar cells (p ‐DSSCs). The improvement in the photovoltaic performance of such devices also depends on the increase of the efficient dye loading by significant enhanced specific surface areas. This work reports for the first time the fabrication of the three‐dimensional (3D) hierarchical flower‐like CuGaO2 nanostructures in a high uniformity by a facile one‐step hydrothermal synthesis. The growth mechanism and the effects of the reaction parameters (time and reducing agent) on the formation of the 3D hierarchical flower‐like CuGaO2 nanostructures were investigated in detailed. It is significantly to note that the prepared 3D hierarchical flower‐like CuGaO2 nanostructures exhibit the highest specific surface areas reported (60 m2/g with ethylene glycol). Due to the efficient dye loading by high specific surface areas, the performance of p ‐DSSCs based on delafossite CuGaO2 is enhanced. Thereby, based on the optical investigation, electrochemical impedance measurement and Mott–Schottky plots, the improved performance can be attributed to high loading of the dye molecules, the enhanced light‐scattering and the reduced interface recombination.
Precise radial velocities of giant stars
Authors: Reichert Katja , Reffert Sabine , Stock Stephan , Trifonov Trifon , Quirrenbach Andreas 
Published: March 2019

Context. Radial-velocity variations of the K giant star Aldebaran (α Tau) were first reported in the early 1990s. After subsequent analyses, the radial-velocity variability with a period of ∼629 d has recently been interpreted as caused by a planet of several Jovian masses.
Aims. We want to further investigate the hypothesis of an extrasolar planet around Aldebaran.
Methods. We combine 165 new radial-velocity measurements from Lick Observatory with seven already published data sets comprising 373 radial-velocity measurements. We perform statistical analyses and investigate whether a Keplerian model properly fits the radial velocities. We also perform a dynamical stability analysis for a possible two-planet solution. Furthermore, the possibility of oscillatory convective modes as cause for the observed radial-velocity variability is discussed.
Results. As best Keplerian fit to the combined radial-velocity data we obtain an orbit for the hypothetical planet with a smaller period (P = 607 d) and a larger eccentricity (e = 0.33 ± 0.04) than the previously proposed one. However, the residual scatter around that fit is still large, with a standard deviation of 117 ms−1. In 2006/2007, the statistical power of the ∼620 d period showed a temporary but significant decrease. Plotting the growth of power in reverse chronological order reveals that a period around 620 d is clearly present in the newest data but not in the data taken before ∼2006. Furthermore, an apparent phase shift between radial-velocity data and orbital solution is observable at certain times. A two-planet Keplerian fit matches the data considerably better than a single-planet solution, but poses severe dynamical stability issues.
Conclusions. The radial-velocity data from Lick Observatory do not further support but in fact weaken the hypothesis of a substellar companion around Aldebaran. Oscillatory convective modes might be a plausible alternative explanation of the observed radial-velocity variations.
Abundances of disk and bulge giants from high-resolution optical spectra
Authors: Lomaeva M. , Jönsson H. , Ryde N. , Schultheis M. , Thorsbro B. 
Published: March 2019

Context. The formation and evolution of the Galactic bulge and the Milky Way is still a debated subject. Observations of the X-shaped bulge, cylindrical stellar motions, and the presumed existence of a fraction of young stars in the bulge have suggested that it formed through secular evolution of the disk and not through gas dissipation and/or mergers, as thought previously.
Aims. Our goal was to measure the abundances of six iron-peak elements (Sc, V, Cr, Mn, Co, and Ni) in the local thin and thick disks and in the bulge. These abundances can provide additional observational constraints for Galaxy formation and chemical evolution models, and help us to understand whether the bulge has emerged from the thick disk or not.
Methods. We use high-resolution optical spectra of 291 K giants in the local disk mostly obtained by the FIES at NOT (signal-to-noise ratio (S/N) of 80–100) and 45 K giants in the bulge obtained by the UVES/FLAMES at VLT (S/N of 10–80). The abundances are measured using Spectroscopy Made Easy (SME). Additionally, we apply non-local thermodynamic equilibrium corrections to the ratios [Mn/Fe] and [Co/Fe]. The thin and thick disks were separated according to their metallicity, [Ti/Fe], as well as proper motions and the radial velocities from Gaia DR2.
Results. The trend of [V/Fe] vs. [Fe/H] shows a separation between the disk components, being more enhanced in the thick disk. Similarly, the [Co/Fe] vs. [Fe/H] trend shows a hint of an enhancement in the local thick disk. The trends of V and Co in the bulge appear to be even more enhanced, although within the uncertainties. The decreasing value of [Sc/Fe] with increasing metallicity is observed in all the components, while our [Mn/Fe] value steadily increases with increasing metallicity in the local disk and the bulge instead. For Cr and Ni we find a flat trend following iron for the whole metallicity range in the disk and the bulge. The ratio of [Ni/Fe] appears slightly overabundant in the thick disk and the bulge compared to the thin disk, although the difference is minor.
Conclusions. The somewhat enhanced ratios of [V/Fe] and [Co/Fe] observed in the bulge suggest that the local thick disk and the bulge might have experienced different chemical enrichment and evolutionary paths. However, we are unable to predict the exact evolutionary path of the bulge solely based on these observations. Galactic chemical evolution models could, on the other hand, allow us to predict them using these results.
Gaia DR2 unravels incompleteness of nearby cluster population: new open clusters in the direction of Perseus
Authors: Cantat-Gaudin T. , Krone-Martins A. , Sedaghat N. , Farahi A. , de Souza R. S. , Skalidis R. , Malz A. I. , Macêdo S. , Moews B. , Jordi C. , Moitinho A. , Castro-Ginard A. , Ishida E. E. O. , Heneka C. , Boucaud A. , Trindade A. M. M. 
Published: March 2019

Context. Open clusters (OCs) are popular tracers of the structure and evolutionary history of the Galactic disc. The OC population is often considered to be complete within 1.8 kpc of the Sun. The recent Gaia Data Release 2 (DR2) allows the latter claim to be challenged.
Aims. We perform a systematic search for new OCs in the direction of Perseus using precise and accurate astrometry from Gaia DR2.
Methods. We implemented a coarse-to-fine search method. First, we exploited spatial proximity using a fast density-aware partitioning of the sky via a k-d tree in the spatial domain of Galactic coordinates, (l, b). Secondly, we employed a Gaussian mixture model in the proper motion space to tag fields quickly around OC candidates. Thirdly, we applied an unsupervised membership assignment method, UPMASK, to scrutinise the candidates. We visually inspected colour-magnitude diagrams to validate the detected objects. Finally, we performed a diagnostic to quantify the significance of each identified over-density in proper motion and in parallax space.
Results. We report the discovery of 41 new stellar clusters. This represents an increment of at least 20% of the previously known OC population in this volume of the Milky Way. We also report on the clear identification of NGC 886, an object previously considered an asterism. This study challenges the previous claim of a near-complete sample of OCs up to 1.8 kpc. Our results reveal that this claim requires revision, and a complete census of nearby OCs is yet to be found.
Pluto’s ephemeris from ground-based stellar occultations (1988–2016)
Authors: Desmars J. , Meza E. , Sicardy B. , Assafin M. , Camargo J. I. B. , Braga-Ribas F. , Benedetti-Rossi G. , Dias-Oliveira A. , Morgado B. , Gomes-Júnior A. R. , Vieira-Martins R. , Behrend R. , Ortiz J. L. , Duffard R. , Morales N. , Santos Sanz P. 
Published: March 2019

Context. From 1988 to 2016, several stellar occultations have been observed to characterise Pluto’s atmosphere and its evolution. From each stellar occultation, an accurate astrometric position of Pluto at the observation epoch is derived. These positions mainly depend on the position of the occulted star and the precision of the timing.
Aims. We present 19 Pluto’s astrometric positions derived from occultations from 1988 to 2016. Using Gaia DR2 for the positions of the occulted stars, the accuracy of these positions is estimated at 2−10 mas, depending on the observation circumstances. From these astrometric positions, we derive an updated ephemeris of Pluto’s system barycentre using the NIMA code.
Methods. The astrometric positions were derived by fitting the light curves of the occultation by a model of Pluto’s atmosphere. The fits provide the observed position of the centre for a reference star position. In most cases other publications provided the circumstances of the occultation such as the coordinates of the stations, timing, and impact parameter, i.e. the closest distance between the station and centre of the shadow. From these parameters, we used a procedure based on the Bessel method to derive an astrometric position.
Results. We derive accurate Pluto’s astrometric positions from 1988 to 2016. These positions are used to refine the orbit of Pluto’system barycentre providing an ephemeris, accurate to the milliarcsecond level, over the period 2000−2020, allowing for better predictions for future stellar occultations.
Comparative analysis of microRNA profiles between wild and cultured Haemaphysalis longicornis (Acari, Ixodidae) ticks
Authors: Luo Jin , Ren Qiaoyun , Chen Ze , Liu Wenge , Qu Zhiqiang , Xiao Ronghai , Chen Ronggui , Lin Hanliang , Wu Zegong , Luo Jianxun , Yin Hong , Wang Hui , Liu Guangyuan 
Published: March 2019

The miRNA profiles of a Haemaphysalis longicornis wild-type (HLWS) and of a Haemaphysalis longicornis cultured population (HLCS) were sequenced using the Illumina Hiseq 4000 platform combined with bioinformatics analysis and real-time polymerase chain reaction (RT-PCR). A total of 15.63 and 15.48 million raw reads were acquired for HLWS and HLCS, respectively. The data identified 1517 and 1327 known conserved miRNAs, respectively, of which 342 were differentially expressed between the two libraries. Thirty-six novel candidate miRNAs were predicted. To explain the functions of these novel miRNAs, Gene Ontology (GO) analysis was performed. Target gene function prediction identified a significant set of genes related to salivary gland development, pathogen-host interaction and regulation of the defence response to pathogens expressed by wild H. longicornis ticks. Cellular component biogenesis, the immune system process, and responses to stimuli were represented at high percentages in the two tick libraries. GO enrichment analysis showed that the percentages of most predicted functions of the target genes of miRNA were similar, as were certain specific categories of functional enhancements, and that these genes had different numbers and specific functions (e.g., auxiliary transport protein and electron carrier functions). This study provides novel findings showing that miRNA regulation affects the expression of immune genes, indicating a considerable influence of environment-induced stressful stimulation on immune homeostasis. Differences in the living environments of ticks can lead to differences in miRNAs between ticks and provide a basis and a convenient means to screen for genes encoding immune factors in ticks.
Cardiac Biomarkers: What Is and What Can Be
Authors: Jacob Rachel , Khan Mahmood 
Published: March 2019

AbstractCardiac biomarkers are of great importance in the timely, accurate diagnosis and management of acute coronary syndrome as well as the prognosis. Diagnosis in the golden period is of utmost importance to institute therapy at the earliest and possibly reverse the myocardial damage. Cardiac biomarkers are also a powerful tool for triaging. Among the many biomarkers, the earliest examined were the myocardial enzymes, several myocardial proteins, peptides, and many other molecules. The latest addition to the repertoire is the microRNAs, which are stable molecules detectable in circulation. About four groups are found to be involved in regulation of circulatory system, and some show promise as specific and early markers of acute coronary syndrome and cardiac dysfunction. As in other fields of medicine, personalized precise treatment may be possible with the use of microRNAs. However, as of now, a multipronged approach, involving different markers of which troponins are necessary, seems to be the best way forward.
Safeuristics! Do Heuristic Evaluation Violation Severity Ratings Correlate with Patient Safety Severity Ratings for a Native Electronic Health Record Mobile Application?
Authors: Kennedy Brandan , Kerns Ellen , Chan Y. , Chaparro Barbara , Fouquet Sarah 
Published: March 2019

Objective Usability of electronic health records (EHRs) remains challenging, and poor EHR design has patient safety implications. Heuristic evaluation detects usability issues that can be classified by severity. The National Institute of Standards and Technology provides a safety scale for EHR usability. Our objectives were to investigate the relationship between heuristic severity ratings and safety scale ratings in an effort to analyze EHR safety.
Materials and Methods Heuristic evaluation was conducted on seven common mobile EHR tasks, revealing 58 heuristic violations and 28 unique usability issues. Each usability issue was independently scored for severity by trained hospitalists and a Human Factors researcher and for safety severity by two physician informaticists and two clinical safety professionals.
Results Results demonstrated a positive correlation between heuristic severity and safety severity ratings. Regression analysis demonstrated that 49% of safety risk variability by clinical safety professionals (r = 0.70; n = 28) and 42% of safety risk variability by clinical informatics specialists (r = 0.65; n = 28) was explained by usability severity scoring of problems outlined by heuristic evaluation. Higher severity ratings of the usability issues were associated with increased perceptions of patient safety risk.
Discussion This study demonstrated the use of heuristic evaluation as a technique to quickly identify usability problems in an EHR that could lead to safety issues. Detection of higher severity ratings could help prioritize failures in EHR design that more urgently require design changes. This approach is a cost-effective technique for improving usability while impacting patient safety.
Conclusion Results from this study demonstrate the efficacy of the heuristic evaluation technique to identify usability problems that impact safety of the EHR. Also, the use of interdisciplinary teams for evaluation should be considered for severity assessment.