Hasil untuk "astro-ph.EP"

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S2 Open Access 2018
The GALAH Survey: Second Data Release

S. Buder, M. Asplund, L. Duong et al.

The Galactic Archaeology with HERMES (GALAH) survey is a large-scale stellar spectroscopic survey of theMilkyWay, designed to deliver complementary chemical information to a large number of stars covered by the Gaia mission. We present the GALAH second public data release (GALAH DR2) containing 342 682 stars. For these stars, the GALAH collaboration provides stellar parameters and abundances for up to 23 elements to the community. Here we present the target selection, observation, data reduction, and detailed explanation of how the spectra were analysed to estimate stellar parameters and element abundances. For the stellar analysis, we have used a multistep approach. We use the physics-driven spectrum synthesis of Spectroscopy Made Easy (SME) to derive stellar labels (T eff , logg, [Fe/H], [X/Fe], v mic , vsin i, AK S ) for a representative training set of stars. This information is then propagated to the whole sample with the data-driven method of The Cannon. Special care has been exercised in the spectral synthesis to only consider spectral lines that have reliable atomic input data and are little affected by blending lines. Departures from local thermodynamic equilibrium (LTE) are considered for several key elements, including Li, O, Na, Mg, Al, Si, and Fe, using 1D MARCS stellar atmosphere models. Validation tests including repeat observations, Gaia benchmark stars, open and globular clusters, and K2 asteroseismic targets lend confidence to our methods and results. Combining the GALAH DR2 catalogue with the kinematic information from Gaia will enable a wide range of Galactic Archaeology studies, with unprecedented detail, dimensionality, and scope.

253 sitasi en Physics
CrossRef Open Access 2025
Nonlinear quantum optics at a topological interface enabled by defect engineering

L. Hallacy, N. J. Martin, M. Jalali Mehrabad et al.

Abstract The integration of topology into photonics has generated a new design framework for constructing robust and unidirectional waveguides, which are not feasible with traditional photonic devices. Here, we overcome current barriers to the successful integration of quantum emitters such as quantum dots (QDs) into valley-Hall (VH) topological waveguides, utilising photonic defects at the topological interface to stabilise the local charge environment and inverse design for efficient topological-conventional mode conversion. By incorporating QDs within defects of VH-photonic crystals, we demonstrate the first instances of single-photon resonant fluorescence and resonant transmission spectroscopy of a quantum emitter at a topological waveguide interface. Our results bring together topological photonics with optical nonlinear effects at the single-photon level, offering a new avenue to investigate the interaction between topology and quantum nonlinear systems.

5 sitasi en
CrossRef Open Access 2024
Simulating Weak Attacks in a New Duplication–Divergence Model with Node Loss

Ruihua Zhang, Gesine Reinert

A better understanding of protein–protein interaction (PPI) networks representing physical interactions between proteins could be beneficial for evolutionary insights as well as for practical applications such as drug development. As a statistical model for PPI networks, duplication–divergence models have been proposed, but they suffer from resulting in either very sparse networks in which most of the proteins are isolated, or in networks which are much denser than what is usually observed, having almost no isolated proteins. Moreover, in real networks, where a gene codes a protein, gene loss may occur. The loss of nodes has not been captured in duplication–divergence models to date. Here, we introduce a new duplication–divergence model which includes node loss. This mechanism results in networks in which the proportion of isolated proteins can take on values which are strictly between 0 and 1. To understand this new model, we apply strong and weak attacks to networks from duplication–divergence models with and without node loss, and compare the results to those obtained when carrying out similar attacks on two real PPI networks of E. coli and of S. cerevisiae. We find that the new model more closely reflects the damage caused by strong and weak attacks found in the PPI networks.

S2 Open Access 2021
Dampak Kebijakan Merdeka Belajar Kampus Merdeka (MBKM) pada Perguruan Tinggi Swasta di Indonesia

K. D. P. Meke, R. B. Astro, M. H. Daud

Merdeka Belajar Kampus Merdeka (MBKM) adalah program pembelajaran pendidikan tinggi yang mandiri dan serbaguna yang dirancang untuk menciptakan komunitas pembelajaran kreatif yang tidak membatasi yang memenuhi kebutuhan mahasiswa Penelitian ini bertujuan untuk untuk melihat dampak dan persepsi penerapan Merdeka Belajar Kampus Merdeka (MBKM) kepada seluruh mahasiswa di perguruan tinggi swasta dengan tujuan untuk melihat sejauh mana pemahaman dan persepsi mahasiswa dan dampak dari penerapan program Merdeka Belajar Kampus Merdeka (MBKM) yang ada di Perguruan Tinggi. Penelitian ini merupakan penelitian deskriptif dengan pendekatan kuantitatif dengan metode survei. Data diperoleh dari populasi yakni 96 responden yang merupakan mahasiswa Program Studi Pendidikan Biologi Universitas Flores. Data dikumpulkan melalui kuesioner. Teknik analisis data dimulai dari pengumpulan data kemudian dianalisis menggunakan analisis deskriptif. Hasil dari penelitian survei ini menunjukan bahwa mahasiswa  pada program studi pendidikan biologi, Fakultas Keguruan dan Ilmu Pendidikan (FKIP) Universitas Flores memberikan respon yang positif terhadap program Merdeka Belajar Kampus Merdeka (MBKM).

85 sitasi en
CrossRef Open Access 2023
pH-Activated Dissolvable Polymeric Coatings to Reduce Biofouling on Electrochemical Sensors

Ahmet Uçar, Eva González-Fernández, Matteo Staderini et al.

Implantable electrochemical sensors that enable the real-time detection of significant biomarkers offer huge potential for the enhancement and personalisation of therapies; however, biofouling is a key challenge encountered by any implantable system. This is particularly an issue immediately after implantation, when the foreign body response and associated biofouling processes are at their most active in passivating a foreign object. Here, we present the development of a sensor protection and activation strategy against biofouling, based on coatings consisting of a pH-triggered, dissolvable polymer, that covered a functionalised electrode surface. We demonstrate that reproducible delayed sensor activation can be achieved, and that the length of this delay can be controlled by the optimisation of coating thickness, homogeneity and density through tuning of the coating method and temperature. Comparative evaluation of the polymer-coated and uncoated probe-modified electrodes in biological media revealed significant improvements in their anti-biofouling characteristics, demonstrating that this offers a promising approach to the design of enhanced sensing devices.

S2 Open Access 2023
A transcriptomic signature of X chromosome overdosage in Saudi Klinefelter syndrome induced pluripotent stem cells

V. Astro, E. Fiacco, Kelly J. Cardona-Londoño et al.

Objective The transcriptional landscape of Klinefelter syndromeduring early embryogenesis remains elusive. This study aimed to evaluate the impact of X chromosome overdosage in 47,XXY males induced pluripotent stem cells (iPSCs) obtained from patients with different genomic backgrounds and ethnicities. Design and method We derived and characterized 15 iPSC lines from four Saudi 47,XXY KS patients and one Saudi 46,XY male. We performed a comparative transcriptional analysis using the Saudi KS-iPSCs and a cohort of European and North American KS-iPSCs. Results We identified a panel of X-linked and autosomal genes commonly dysregulated in Saudi and European/North American KS-iPSCs vs 46,XY controls. Our findings demonstrate that seven PAR1 and nine non-PAR escape genes are consistently dysregulated and mostly display comparable transcriptional levels in both groups. Finally, we focused on genes commonly dysregulated in both iPSC cohorts and identified several gene-ontology categories highly relevant to KS physiopathology, including aberrant cardiac muscle contractility, skeletal muscle defects, abnormal synaptic transmission, and behavioral alterations. Conclusions Our results indicate that a transcriptomic signature of X chromosome overdosage in KS is potentially attributable to a subset of X-linked genes sensitive to sex chromosome dosage and escaping X inactivation, regardless of the geographical area of origin, ethnicity, and genetic makeup.

3 sitasi en Medicine
CrossRef Open Access 2023
Investigation of the Superlattice Phases Formed in Ta72Ru28

Alexander W. Carruthers, Bradley A. Young, Ed J. Pickering

The Ta-Ru binary phase diagram has not been fully investigated, but shows potential for a two-phase region of A2 + B2. Given the high melting points of both Ta and Ru, such an alloy would have the potential for high temperature strength. A Ta72Ru28 alloy was arc melted and investigated in the as-cast and aged (at 1000 °C) states. The as cast alloy was composed of A2 and B2, albeit not in a superalloy-like morphology. A third phase was found in the aged alloy, which has not been reported before, and which is also a coherent superlattice phase of the Ta BCC matrix. The structure of this phase was found to be consistent with the tetragonal Cr2Al prototype structure, with lattice parameters of (a, a, 3a), where a is the Ta BCC lattice parameter.

CrossRef Open Access 2022
Laser Written Stretchable Diffractive Optic Elements in Liquid Crystal Gels

Bohan Chen, Zimo Zhao, Camron Nourshargh et al.

Direct laser writing (DLW) in liquid crystals (LCs) enables a range of new stimuli-responsive functionality to be realized. Here, a method of fabricating mechanically tunable diffraction gratings in stretchable LC gels is demonstrated using a combination of two-photon polymerization direct laser writing (TPP-DLW) and ultraviolet (UV) irradiation. Results are presented that demonstrate the fabrication of a diffraction grating that is written using TPP-DLW in the presence of an electric field in order to align and lock-in the LC director in a homeotropic configuration. The electric field is subsequently removed and the surrounding regions of the LC layer are then exposed to UV light to freeze-in a different alignment so as to ensure that there is a phase difference between the laser written and UV illuminated polymerized regions. It is found that there is a change in the period of the diffraction grating when observed on a polarizing optical microscope as well as a change in the far-field diffraction pattern when the film is stretched or contracted. These experimental results are then compared with the results from simulations. The paper concludes with a demonstration of tuning of the far-field diffraction pattern of a 2-dimensional diffraction grating.

CrossRef Open Access 2022
Characterisation of a Complex CaZr0.9Ce0.1Ti2O7 Glass–Ceramic Produced by Hot Isostatic Pressing

Malin C. J. Dixon Wilkins, Clémence Gausse, Luke T. Townsend et al.

The behaviour of Ce-containing zirconolites in hot isostatically pressed (HIPed) materials is complex, characterised by redox interactions between the metallic HIP canister that result in reduction of Ce4+ to Ce3+. In this work, a glass–ceramic of composition 70 wt.% CaZr0.9Ce0.1Ti2O7 ceramic in 30 wt.% Na2Al2Si6O16 glass was produced by HIP (approx. 170 cm3 canister) to examine the extent of the material–canister interaction. A complex material with six distinct regions was produced, with the extent of Ce reduction varying depending on the distance from the canister. Notably, the innermost bulk regions (those approximately 7 mm from the canister) contained only Ce4+, demonstrating that a production-scale HIPed glass–ceramic would indeed have a bulk region unaffected by the reducing environment induced by a ferrous HIP canister despite the flow of glass at the HIP temperature. Each of the six regions was characterised by XRD (including Rietveld method refinements), SEM/EDX and linear combination fitting of Ce L3-edge XANES spectra. Regions in the lower part of the canister were found to contain a significantly higher fraction of Ce4+ compared to the upper regions. Though zirconolite-2M was the major crystalline phase observed in all regions, the relative abundances of minor phases (including sphene, baddeleyite, rutile and perovskite) were higher in the outermost regions, which comprised a significantly reduced Ce inventory.

S2 Open Access 2021
Multi-institutional retrospective analysis of ultrahypofractionated radiotherapy for Japanese prostate cancer patients

H. Ishiyama, H. Tsumura, H. Nagano et al.

To report outcomes and risk factors of ultrahypofractionated (UHF) radiotherapy for Japanese prostate cancer patients. This multi-institutional retrospective analysis comprised 259 patients with localized prostate cancer from 6 hospitals. A total dose of 35–36 Gy in 4–5 fractions was prescribed for sequential or alternate-day administration. Biochemical failure was defined according to the Phoenix ASTRO consensus. Toxicities were assessed using National Cancer Institute Common Toxicity Criteria version 4. Tumor control and toxicity rates were analyzed by competing risk frames. Median follow-up duration was 32 months (range 22–97 months). 2- and 3-year biochemical control rates were 97.7% and 96.4%, respectively. Initial prostate-specific antigen (p < 0.01) and neoadjuvant androgen deprivation therapy (p < 0.05) were identified as risk factors for biochemical recurrence. 2- and 3-year cumulative ≥ Grade 2 late genitourinary (GU) toxicities were 5.8% and 7.4%, respectively. Corresponding rates of gastrointestinal (GI) toxicities were 3.9% and 4.5%, respectively. Grade 3 rates were lower than 1% for both GU and GI toxicities. No grade 4 or higher toxicities were encountered. Biologically effective dose was identified as a risk factor for ≥ Grade 2 late GU and GI toxicities (p < 0.05). UHF radiotherapy offered effective, safe treatment for Japanese prostate cancer with short-term follow-up. Our result suggest higher prescribed doses are related to higher toxicity rates.

7 sitasi en Medicine
S2 Open Access 2021
Improvement of QDaedalus measurements with continuous detection of environmental parameters

L. Völgyesi, G. Tóth

QDaedalus is an automated, computer-controlled astro-geodetic measurement system. Astronomical deflections of the vertical measured by the QDaedalus system are significantly influenced by atmospheric refraction. Therefore, the measuring system was further improved by recording the environmental parameters influencing the refraction (air pressure, temperature, humidity) with accurate and high time resolution. In addition to meteorological parameters, refraction also depends on the spectrum of the stars. Both the continuously measured meteorological parameters and the color of the stars were taken into account in the calculation of the refraction. To control the method, we used the deflection of the vertical values of the Pistahegy point in the southern part of Budapest which were determined over 7 years during 260 night measurements. The corrected measurements fit within 0.01" with the average value of previous Pistahegy measurements. The standard deviation of the differences due to the corrections, however, may reach 0.015" for the DOV components.

5 sitasi en
S2 Open Access 2021
Improved Complexity Of Trust-Region Optimization For Zeroth-Order Stochastic Oracles with Adaptive Sampling

Yunsoo Ha, S. Shashaani, Quoc Tran-Dinh

We present an enhanced stochastic trust-region optimization with adaptive sampling (ASTRO-DF) in which optimizing an iteratively constructed local model on estimates of objective values with stochastic sample size guides the search. The noticeable feature is that the underdetermined quadratic model with a diagonal Hessian requires fewer function evaluations, which is particularly useful at high dimensions. This paper describes the enhanced algorithm in detail. It gives several theoretical results, including iteration complexity, and renders almost sure convergence guarantees. We report in our numerical experience the finite-time superiority of the enhanced ASTRO-DF over state-of-the-art using the SimOpt library.

5 sitasi en Computer Science
CrossRef Open Access 2020
The Influence of pH on the Combustion Properties of Bio-Coal Following Hydrothermal Treatment of Swine Manure

Aidan Mark Smith, Ugochinyere Ekpo, Andrew Barry Ross

The application of excessive amounts of manure to soil prompted interest in using alternative approaches for treating slurry. One promising technology is hydrothermal carbonisation (HTC) which can recover nutrients such as phosphorus and nitrogen while simultaneously making a solid fuel. Processing manure under acidic conditions can facilitate nutrient recovery; however, very few studies considered the implications of operating at low pH on the combustion properties of the resulting bio-coal. In this work, swine manure was hydrothermally treated at temperatures ranging from 120 to 250 °C in either water alone or reagents including 0.1 M NaOH, 0.1 M H2SO4, and finally 0.1 M organic acid (CH3COOH and HCOOH). The influence of pH on the HTC process and the combustion properties of the resulting bio-coals was assessed. The results indicate that pH has a strong influence on ash chemistry, with decreasing pH resulting in an increased removal of ash. The reduction in mineral matter influences the volatile content of the bio-coal and its energy content. As the ash content in the final bio-coal reduces, the energy density increases. Treatment at 250 °C results in a more “coal like” bio-coal with fuel properties similar to that of lignite coal and a higher heating value (HHV) ranging between 21 and 23 MJ/kg depending on pH. Processing at low pH results in favourable ash chemistry in terms of slagging and fouling. Operating at low pH also appears to influence the level of dehydration during HTC. The level of dehydration increases with decreasing pH, although this effect is reduced at higher temperatures. At higher-temperature processing (250 °C), operating at lower pH increases the yield of bio-coal; however, at lower temperatures (below 200 °C), the reverse is true. The lower yields obtained below 200 °C in the presence of acid may be due to acid hydrolysis of carbohydrate in the manure, whereas, at the higher temperatures, it may be due to the acid promoting polymerisation.

CrossRef Open Access 2020
Neural and physiological data from participants listening to affective music

Ian Daly, Nicoletta Nicolaou, Duncan Williams et al.

AbstractMusic provides a means of communicating affective meaning. However, the neurological mechanisms by which music induces affect are not fully understood. Our project sought to investigate this through a series of experiments into how humans react to affective musical stimuli and how physiological and neurological signals recorded from those participants change in accordance with self-reported changes in affect. In this paper, the datasets recorded over the course of this project are presented, including details of the musical stimuli, participant reports of their felt changes in affective states as they listened to the music, and concomitant recordings of physiological and neurological activity. We also include non-identifying meta data on our participant populations for purposes of further exploratory analysis. This data provides a large and valuable novel resource for researchers investigating emotion, music, and how they affect our neural and physiological activity.

18 sitasi en
S2 Open Access 2020
The astrophysical odds of GW151216

G. Ashton, E. Thrane

The gravitational-wave candidate GW151216 is a proposed binary black hole event from the first observing run of the Advanced LIGO detectors. Not identified as a bona fide signal by the LIGO--Virgo collaboration, there is disagreement as to its authenticity, which is quantified by $p_\text{astro}$, the probability that the event is astrophysical in origin. Previous estimates of $p_\text{astro}$ from different groups range from 0.18 to 0.71, making it unclear whether this event should be included in population analyses, which typically require $p_\text{astro}>0.5$. Whether GW151216 is an astrophysical signal or not has implications for the population properties of stellar-mass black holes and hence the evolution of massive stars. Using the astrophysical odds, a Bayesian method which uses the signal coherence between detectors and a parameterised model of non-astrophysical detector noise, we find that $p_\text{astro}=0.03$, suggesting that GW151216 is unlikely to be a genuine signal. We also analyse GW150914 (the first gravitational-wave detection) and GW151012 (initially considered to be an ambiguous detection) and find $p_\text{astro}$ values of 1 and 0.997 respectively. We argue that the astrophysical odds presented here improve upon traditional methods for distinguishing signals from noise.

11 sitasi en Physics
S2 Open Access 2019
Analytical ray-tracing in planetary atmospheres

A. Bourgoin, M. Zannoni, P. Tortora

Context. Ground-based astro-geodetic observations and atmospheric radio occultations are two examples of observational techniques requiring a scrutiny analysis of atmospheric refraction. In both cases, the measured changes of the observables are geometrically related to changes in the photon path through the refractive profile of the crossed medium. Therefore, having a clear knowledge of how the refractivity governs the photon path evolution is of prime importance to clearly understand observational features. Aims. We analytically performed the integration of the photon path and the light time of rays traveling across a non-spherically symmetric planetary atmosphere. Methods. Assuming that the atmospheric refraction evolves linearly with the Newtonian potential, we derived an exact solution to the equations of geometrical optics. By varying the solution’s arbitrary constants of integration, we reformulated the equation of geometrical optics into a new set of osculating equations describing the constants’ evolution following any changes in the refractive profile. We have highlighted the capabilities of the formalism, carrying out five realistic applications in which we derived analytical expressions. Finally, we assessed the accuracy by comparing the solution to results from a numerical integration of the equations of geometrical optics in the presence of a quadrupolar moment (J2). Results. Analytical expressions for the light time and the refractive bending are given with relative errors at the level of one part in 108 and one part in 105, for typical values of the refractivity and J2 at levels of 10−4 and 10−2, respectively. Conclusions. The establishment of the osculating equations for the ray propagation has two main advantages. Firstly, it provides an easy and comprehensive geometrical picture for interpreting the photon path. Secondly, it allows the analytical solving of the ray propagation in the presence of non-radial dependencies in the refractive profile.

13 sitasi en Physics
S2 Open Access 2018
AGILE Detection of Gamma-Ray Sources Coincident with Cosmic Neutrino Events

F. Lucarelli, F. Lucarelli, M. Tavani et al.

The origin of cosmic neutrinos is still largely unknown. Using data obtained by the gamma-ray imager on board the Astro-rivelatore Gamma a Immagini Leggero (AGILE) satellite, we systematically searched for transient gamma-ray sources above 100 MeV that are temporally and spatially coincident with 10 recent high-energy neutrino IceCube events. We found three AGILE candidate sources that can be considered possible counterparts to neutrino events. Detecting three gamma-ray/neutrino associations out of 10 IceCube events is shown to be unlikely due to a chance coincidence. One of the sources is related to the BL Lac source TXS 0506+056. For the other two AGILE gamma-ray sources there are no obvious known counterparts, and both Galactic and extragalactic origin should be considered.

21 sitasi en Physics

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