bluuebunny/crossref_metadata_2025 huggingface dataset:
A Comparative Study on the Faecal Bacterial Community and Potential Zoonotic Bacteria of Muskoxen (Ovibos moschatus) in Northeast Greenland, Northwest Greenland and Norway
Authors: Andersen-Ranberg Emilie U. , Barnes Christopher J. , Rasmussen Linett , Salgado-Flores Alejandro , Grøndahl Carsten , Mosbacher Jesper B. , Hansen Anders J. , Sundset Monica Alterskjær , Schmidt Niels Martin , Sonne Christian
Published: July 2018

Muskoxen (Ovibos moschatus) are ruminants adapted to a high-fibre diet. There is increasing interest in the role that gut microbes play in the digestion and utilization of these specialized diets but only limited data available on the gut microbiome of high-Arctic animals. In this study, we metabarcoded the 16S rRNA region of faecal samples from muskoxen of Northeast Greenland, Northwest Greenland and Norway, and quantified the effects of physiological and temporal factors on bacterial composition. We found significant effects of body mass, year of sampling and location on the gut bacterial communities of North East Greenland muskoxen. These effects were however dwarfed by the effects of location, emphasizing the importance of the local ecology on the gut bacterial community. Habitat alterations and rising temperatures may therefore have a considerable impact on muskoxen health and reproductive success. Moreover, muskoxen are hunted and consumed in Greenland, Canada and Alaska; therefore, this study also screened for potential zoonoses of food safety interest. A total of 13 potentially zoonotic genera were identified, including the genera Erysipelothrix and Yersinia implicated in recent mass die-offs of the muskoxen themselves.
Comparative Study of Carborane- and Phenyl-Modified Adenosine Derivatives as Ligands for the A2A and A3 Adenosine Receptors Based on a Rigid in Silico Docking and Radioligand Replacement Assay
Authors: Vincenzi Marian , Bednarska Katarzyna , Leśnikowski Zbigniew J.
Published: July 2018

Adenosine receptors are involved in many physiological processes and pathological conditions and are therefore attractive therapeutic targets. To identify new types of effective ligands for these receptors, a library of adenosine derivatives bearing a boron cluster or phenyl group in the same position was designed. The ligands were screened in silico to determine their calculated affinities for the A2A and A3 adenosine receptors. An virtual screening protocol based on the PatchDock web server was developed. In the first screening phase, the effects of the functional group (organic or inorganic modulator) on the adenosine ligand affinity for the receptors were determined. Then, the lead compounds were identified for each receptor in the second virtual screening phase. Two pairs of the most promising ligands, compounds 3 and 4, and two ligands with lower affinity scores (compounds 11 and 12, one with a boron cluster and one with a phenyl group) were synthesized and tested in a radioligand replacement assay for affinity to the A2A and A3 receptors. A reasonable correlation of in silico and biological assay results was observed. In addition, the effects of a phenyl group and boron cluster, which is new adenosine modifiers, on the adenosine ligand binding were compared.
Alpha-Mangostin-Rich Extracts from Mangosteen Pericarp: Optimization of Green Extraction Protocol and Evaluation of Biological Activity
Authors: Ghasemzadeh Ali , Jaafar Hawa Z. E. , Baghdadi Ali , Tayebi-Meigooni Amin
Published: July 2018

Since α-mangostin in mangosteen fruits was reported to be the main compound able to provide natural antioxidants, the microwave-assisted extraction process to obtain high-quality α-mangostin from mangosteen pericarp (Garcinia mangostana L.) was optimized using a central composite design and response surface methodology. The parameters examined included extraction time, microwave power, and solvent percentage. The antioxidant and antimicrobial activity of optimized and non-optimized extracts was evaluated. Ethyl acetate as a green solvent exhibited the highest concentration of α-mangostin, followed by dichloromethane, ethanol, and water. The highest α-mangostin concentration in mangosteen pericarp of 121.01 mg/g dry matter (DM) was predicted at 3.16 min, 189.20 W, and 72.40% (v/v). The verification of experimental results under these optimized conditions showed that the α-mangostin value for the mangosteen pericarp was 120.68 mg/g DM. The predicted models were successfully developed to extract α-mangostin from the mangosteen pericarp. No significant differences were observed between the predicted and the experimental α-mangostin values, indicating that the developed models are accurate. The analysis of the extracts for secondary metabolites showed that the total phenolic content (TPC) and total flavonoid content (TFC) increased significantly in the optimized extracts (OE) compared to the non-optimized extracts (NOE). Additionally, trans-ferulic acid and catechin were abundant among the compounds identified. In addition, the optimized extract of mangosteen pericarp with its higher α-mangostin and secondary metabolite concentrations exhibited higher antioxidant activities with half maximal inhibitory concentration (IC50) values of 20.64 µg/mL compared to those of the NOE (28.50 µg/mL). The OE exhibited the highest antibacterial activity, particularly against Gram-positive bacteria. In this study, the microwave-assisted extraction process of α-mangostin from mangosteen pericarp was successfully optimized, indicating the accuracy of the models developed, which will be usable in a larger-scale extraction process.
Ascorbic Acid and Glucosinolate Levels in New Czech Cabbage Cultivars: Effect of Production System and Fungal Infection
Authors: Novotny Cenek , Schulzova Vera , Krmela Ales , Hajslova Jana , Svobodova Katerina , Koudela Martin
Published: July 2018

Nutritional value and disease-preventive effects of cabbage are well-known. Levels of the antioxidant compounds ascorbic acid (AA) and glucosinolates (GSL) in new Czech cabbage cultivars were determined in the context of different production systems. The contents of AA and GSLs in cabbage biomass were determined by HPLC. Individual GSLs were identified according to their exact masses with sinigrin used as the external standard. Artificial infection with A. brassicicola generally raised the AA levels. The major GSLs (≥10 mg kg−1) were glucobrassicin, sinigrin, and glucoiberin. Indole and aliphatic GSLs were present, but no aromatic ones were detected. Ecological growth conditions and the artificial fungal infection increased the total content of GSLs and, also, of the methoxylated indole GSLs. Sulforaphane, iberin, indole-3-carbinol, and ascorbigen resulting from the hydrolysis of GSLs were found in both cultivars. The amounts and profiles of GSLs present in the two Czech cultivars demonstrated their good nutritional value. The decomposition products sulforaphane, iberin, indole-3-carbinol, and ascorbigen detected improve its health-promoting qualities and represent a suitable component of the human diet.
A Synergistic Formulation of Plant Extracts Decreases Postprandial Glucose and Insulin Peaks: Results from Two Randomized, Controlled, Cross-Over Studies Using Real-World Meals
Authors: Adamska-Patruno Edyta , Billing-Marczak Katarzyna , Orlowski Marek , Gorska Maria , Krotkiewski Marcin , Kretowski Adam
Published: July 2018

This study investigated the efficacy of a plant-derived dietary supplement with respect to decreasing postprandial glucose and insulin peaks after the intake of real-world meals. Two randomized, double-blind, placebo-controlled, cross-over experiments were conducted on healthy subjects who received a supplement containing extracts of white mulberry, white bean, and green coffee or one containing the three extracts with added fibre before consuming high-GI/GL (glycaemic index/glycaemic load) meals. In study one, 32 subjects received an investigational product/placebo before a standardized meal at two visits. In study two, 150 subjects received an investigational product/placebo before five different standardized meals. Postprandial glucose and insulin concentrations were lower 20–35 min after meal intake among subjects taking the investigational product, and fewer episodes of postprandial reactive hypoglycaemia were noted. For example, after consuming breakfast cereal with milk, lower glucose peaks were observed for the investigational product (vs. placebo) after 20 min (100.2 ± 1.97 vs. 112.5 ± 3.12 mg/dL, respectively; p < 0.01); lower insulin peaks were noted at the same time point (45.9 ± 4.02 IU/mL vs. 68.2 ± 5.53 IU/mL, respectively, p < 0.01). The combined formulation decreases the adverse consequences of high-GI/GL meal consumption. It can be an effective dietary supplement for the management of metabolic syndrome and type 2 diabetes mellitus.
Relationship between Diet and Mental Health in a Young Adult Appalachian College Population
Authors: Wattick Rachel A. , Hagedorn Rebecca L. , Olfert Melissa D.
Published: July 2018

Young adults in Appalachia may face poor nutritional status due to low access to healthy food and high mental health symptoms attributed to high stress and the college environment. A cross-sectional design was used to investigate the relationship between diet intake and mental health status of this population via surveys. Participant responses (n = 1956) showed students’ mean number of depressed days over the past 30 days was 9.67 ± 8.80, and of anxious days, 14.1 ± 10.03. The mean fruit and vegetable intake was 1.80 ± 1.27 times per day and the mean added sugars intake was 1.79 ± 1.26 times per day. 36.7% of students were found to be food insecure. One-way ANOVA and Chi-Squared analyses were used to determine relationship between variables. Significant variables were placed into a full logistic regression model. Food insecurity and fruit and vegetable intake remained significant predictors of depression in males (odds ratio (OR) = 2.33 95% CI 1.47–3.71 and OR = 68 95% CI 50–89, respectively) and in females food insecurity remained a significant predictor of depression (OR = 2.26 95% CI 1.67–3.07). Food insecurity and added sugars intake were significant predictor of anxiety in males (OR = 2.33 95% CI 1.47–3.71 and OR = 1.09 95% CI 0.91–1.3, respectively) and for anxiety in females, added sugars intake and food insecurity were significant predictors (OR = 1.18 95% CI 1.05–1.32 and OR = 1.65 95% CI 1.27–2.16, respectively). Improving college student’s diet intake through increased access to healthy foods could improve the mental health and well-being of students.
The Association of Dietary Cholesterol and Fatty Acids with Dyslipidemia in Chinese Metropolitan Men and Women
Authors: Zhu Zhenni , Wu Fan , Lu Ye , Wang Zhengyuan , Zang Jiajie , Yu Huiting , Guo Changyi , Jia Xiaodong , Shen Xianbiao , Ding Gangqiang
Published: July 2018

Background: The associations between dietary cholesterol and fatty acids and serum lipids are controversial. This study is to examine the association of dietary cholesterol and fatty acids with serum lipids and dyslipidemia in Chinese metropolitan male and female adults. Methods: 3850 participants in the Shanghai Diet and Health Survey were investigated during the period 2012–2013. Information was obtained on dietary intake, anthropometric and blood laboratory measurements. Dyslipidemia was determined by US National Cholesterol Education Program Adult Treatment Panel III (NCEP-ATP III). Results: Dietary cholesterol was in line with serum TC, LDL-C and the LDL-C to HDL-C ratio in general and the partial correlation coefficients were 0.64 (95% CI: 0.13–1.15, p = 0.015), 0.73 (95% CI: 0.21–1.24, p = 0.006) and 0.01 (95% CI: 0.00–0.02, p = 0.018), respectively. The partial correlation coefficients were greater in women. Dietary fatty acids were not associated with serum lipids. The highest quintile of dietary cholesterol intake (≥538.0 mg/day) was associated with an approximate 1.6-fold risk for high TC and high HDL-C compared with the lowest quintile (<193.1 mg/day) generally. Conclusions: Dietary cholesterol was associated with serum cholesterol in Chinese metropolitan adults and a higher risk of dyslipidemia was observed at a high level of dietary cholesterol intake. Whether there should be an upper limit on dietary cholesterol in the Chinese population warrants further study.
Wearable Health Devices—Vital Sign Monitoring, Systems and Technologies
Authors: Dias Duarte , Paulo Silva Cunha João
Published: July 2018

Wearable Health Devices (WHDs) are increasingly helping people to better monitor their health status both at an activity/fitness level for self-health tracking and at a medical level providing more data to clinicians with a potential for earlier diagnostic and guidance of treatment. The technology revolution in the miniaturization of electronic devices is enabling to design more reliable and adaptable wearables, contributing for a world-wide change in the health monitoring approach. In this paper we review important aspects in the WHDs area, listing the state-of-the-art of wearable vital signs sensing technologies plus their system architectures and specifications. A focus on vital signs acquired by WHDs is made: first a discussion about the most important vital signs for health assessment using WHDs is presented and then for each vital sign a description is made concerning its origin and effect on heath, monitoring needs, acquisition methods and WHDs and recent scientific developments on the area (electrocardiogram, heart rate, blood pressure, respiration rate, blood oxygen saturation, blood glucose, skin perspiration, capnography, body temperature, motion evaluation, cardiac implantable devices and ambient parameters). A general WHDs system architecture is presented based on the state-of-the-art. After a global review of WHDs, we zoom in into cardiovascular WHDs, analysing commercial devices and their applicability versus quality, extending this subject to smart t-shirts for medical purposes. Furthermore we present a resumed evolution of these devices based on the prototypes developed along the years. Finally we discuss likely market trends and future challenges for the emerging WHDs area.
The Structure and Activity of Double-Nitroimidazoles. A Mini-Review
Authors: Żwawiak Justyna , Zaprutko Lucjusz
Published: July 2018

Many interesting applications have been found for nitroimidazoles as therapeutic agents. Among others, some of these compounds can radiosensitize hypoxic tumor cells. The introduction of a second nitroimidazole ring to the molecule can improve the level of its pharmacological effect. The aim of this article is to overview the literature concerning active compounds that contain two nitroimidazole moieties in their structures.
Historic Urban Landscapes: A Review on Trends and Methodologies in the Urban Context of the 21st Century
Authors: Azpeitia Santander Arturo , Azkarate Garai-Olaun Agustín , De la Fuente Arana Ander
Published: July 2018

This article makes a critical reflection, questioning the notion of historical urban landscapes as a conceptual paradigm used for the basis of urban conservation in the twenty-first century. The study begins with a brief summary of the origins and subsequent evolution of this concept, highlighting the two key reference milestones: the Vienna Memorandum (UNESCO, 2005) and the Paris Recommendation (UNESCO, 2011). Subsequently, the focus of attention will be on highlighting the problems and difficulties posed by the management and protection of historic urban landscapes today. In this sense, the focus of attention will be placed on the assumption that change is an inherent part of the urban condition, since there is no consensus on what the limits of acceptable change in historic urban landscapes should be. It also emphasizes three factors that make this more difficult: (1) the reminiscences of the doctrines of the Weberian administration in the current models of government; (2) the subjective nature of the systems of indicators applied to the scope of historic cities; and (3) the opportunism of tactical urbanism, which, despite its shortcomings, is becoming an outstanding alternative for the methodological development of the historic urban landscapes.
Building a More Sustainable Society? A Case Study on the Role of Sustainable Development in the Education and Early Career of Water and Environmental Engineers
Authors: Vehmaa Anu , Karvinen Meeri , Keskinen Marko
Published: July 2018

Engineering education is critical for sustainability, given the key role that engineers have in shaping the development of our society. Yet, engineering studies have traditionally not been driven by sustainability-related knowledge and skills, but focused more on general computational skills and technical problem-solving. This has also been the case in our case study, which focuses on recent water and environmental engineering graduates in Finland. We studied the role that sustainable development has had in their education and early career through an extensive questionnaire and semi-structured interviews. The analysis was done in two ways: indirectly by comparing how well the key working life knowledge and skills recognized by the respondents correspond with sustainability-related skills, and directly by studying the graduates’ views towards the sustainable development and their possibilities to advance it in their work. The results show that although sustainability was not at the core of respondents’ studies, their key competencies correspond well with sustainability-related working life skills. The respondents also see that sustainable development has a central role in water and environmental engineering, although it is typically more visible at a strategic rather than a practical level. However, the results also indicate that several early-career engineers have deficient knowledge of sustainable development, and are therefore lacking the ability to fully connect the principles of sustainable development into their own expertise. Overall, the findings suggest that water and environmental engineers with their wide set of competencies have the potential to take on a larger role in building a more sustainable society. To ensure this, engineering education should emphasize the connection between the field and sustainable development and clearly link engineers’ core competencies with the skills required to promote sustainability.
An E-Commerce Platform for Industrialized Construction Procurement Based on BIM and Linked Data
Authors: He Dandan , Li Zhongfu , Wu Chunlin , Ning Xin
Published: July 2018

Industrialized construction has raised the requirements of procurement methods used in the construction industry. The rapid development of e-commerce offers efficient and effective solutions, however the large number of participants in the construction industry means that the data involved are complex, and problems arise related to volume, heterogeneity, and fragmentation. Thus, the sector lags behind others in the adoption of e-commerce. In particular, data integration has become a barrier preventing further development. Traditional e-commerce platform, which considered data integration for common product data, cannot meet the requirements of construction product data integration. This study aimed to build an information-integrated e-commerce platform for industrialized construction procurement (ICP) to overcome some of the shortcomings existing platforms. We proposed a platform based on Building Information Modelling (BIM) and linked data, taking an innovative approach to data integration. It uses industrialized construction technology to support product standardization, BIM to support procurement process, and linked data to connect different data sources. The platform was validated using a case study. With the development of an e-commerce ontology, industrialized construction component information was extracted from BIM models and converted to Resource Description Framework (RDF) format. Related information from different data sources was also converted to RDF format, and Simple Protocol and Resource Description Framework Query Language (SPARQL) queries were implemented. The platform provides a solution for the development of e-commerce platform in the construction industry.
An Efficient Grid-Based K-Prototypes Algorithm for Sustainable Decision-Making on Spatial Objects
Authors: Jang Hong-Jun , Kim Byoungwook , Kim Jongwan , Jung Soon-Young
Published: July 2018

Data mining plays a critical role in sustainable decision-making. Although the k-prototypes algorithm is one of the best-known algorithms for clustering both numeric and categorical data, clustering a large number of spatial objects with mixed numeric and categorical attributes is still inefficient due to complexity. In this paper, we propose an efficient grid-based k-prototypes algorithm, GK-prototypes, which achieves high performance for clustering spatial objects. The first proposed algorithm utilizes both maximum and minimum distance between cluster centers and a cell, which can reduce unnecessary distance calculation. The second proposed algorithm as an extension of the first proposed algorithm, utilizes spatial dependence; spatial data tends to be similar to objects that are close. Each cell has a bitmap index which stores the categorical values of all objects within the same cell for each attribute. This bitmap index can improve performance if the categorical data is skewed. Experimental results show that the proposed algorithms can achieve better performance than the existing pruning techniques of the k-prototypes algorithm.
Computing Metric Dimension and Metric Basis of 2D Lattice of Alpha-Boron Nanotubes
Authors: Hussain Zafar , Munir Mobeen , Chaudhary Maqbool , Kang Shin Min
Published: July 2018

Concepts of resolving set and metric basis has enjoyed a lot of success because of multi-purpose applications both in computer and mathematical sciences. For a connected graph G(V,E) a subset W of V(G) is a resolving set for G if every two vertices of G have distinct representations with respect to W. A resolving set of minimum cardinality is called a metric basis for graph G and this minimum cardinality is known as metric dimension of G. Boron nanotubes with different lattice structures, radii and chirality’s have attracted attention due to their transport properties, electronic structure and structural stability. In the present article, we compute the metric dimension and metric basis of 2D lattices of alpha-boron nanotubes.
A Live-Attenuated Prime, Inactivated Boost Vaccination Strategy with Chimeric Hemagglutinin-Based Universal Influenza Virus Vaccines Provides Protection in Ferrets: A Confirmatory Study
Authors: Nachbagauer Raffael , Krammer Florian , Albrecht Randy A.
Published: July 2018

Influenza viruses cause severe diseases and mortality in humans on an annual basis. The current influenza virus vaccines can confer protection when they are well-matched with the circulating strains. However, due to constant changes of the virus surface glycoproteins, the vaccine efficacy can drop substantially in some seasons. In addition, the current seasonal influenza virus vaccines do not protect from avian influenza viruses of human pandemic potential. Novel influenza virus vaccines that aim to elicit antibodies against conserved epitopes like the hemagglutinin stalk could not only reduce the burden of drifted seasonal viruses but potentially also protect humans from infection with zoonotic and emerging pandemic influenza viruses. In this paper, we generated influenza virus vaccine constructs that express chimeric hemagglutinins consisting of exotic, avian head domains and a consistent stalk domain of a seasonal virus. Using such viruses in a sequential immunization regimen can redirect the immune response towards conserved epitopes. In this study, male ferrets received a live-attenuated vaccine virus based on the A/Ann Arbor/6/60 strain expressing a chimeric H8/1 (cH8/1) hemagglutinin, which was followed by a heterologous booster vaccination with a cH5/1N1 formalin inactivated non-adjuvanted whole virus. This group was compared to a second group that received a cH8/1N1 inactivated vaccine followed by a cH5/1N1 inactivated vaccine. Both groups showed a reduction in viral titers in the upper respiratory tract after the A(H1N1)pdm09 virus challenge. Animals that received the live-attenuated vaccine had low or undetectable titers in the lower respiratory tract. The results support the further development of chimeric hemagglutinin-based vaccination strategies. The outcome of this study confirms and corroborates findings from female ferrets primed with a A/Leningrad/134/17/57-based live attenuated cH8/1N1 vaccine followed by vaccination with an AS03-adjuvanted cH5/1N1 split virus vaccine 10.
Quis fratrem mihi reddit ? Notes sur la famille des légionnaires de Mayence
Authors: Rossignol Benoît
Published: July 2018

We study here 210 funerary inscriptions concerning soldiers from the legions of Mainz from Augustus to the IIIrd century. For the 1st century the sample can be divided in 3 chronologic al periods. During the 1st century, inscriptions making mention of the soldier’s family are in a minority and concerned mainly brothers, especially in the 1st period that gives the greatest number of brothers. From the IInd century the funerary inscriptions making mention of the soldier’s family are the largest number, they mention usually wife and children. Finally we discuss the term frater in our sample. Despite the possibility that it indicates sometimes a military brotherhood we must emphasize the fact that the largest number of brothers in our evidence are biological ones and that it is a signifi cant feature of the recruitment of the Roman army.
Time-resolved WISE/NEOWISE Coadds
Authors: Meisner A. M. , Lang D. , Schlegel D. J.
Published: July 2018

We have used the first ∼3 years of 3.4 μm (W1) and 4.6 μm (W2) observations from the WISE and NEOWISE missions to create a full-sky set of time-resolved coadds. As a result of the WISE survey strategy, a typical sky location is visited every six months and is observed during ≳12 exposures per visit, with these exposures spanning a ∼1 day time interval. We have stacked the exposures within such ∼1 day intervals to produce one coadd per band per visit—that is, one coadd every six months at a given position on the sky in each of W1 and W2. For most parts of the sky, we have generated six epochal coadds per band, with one visit during the fully cryogenic WISE mission, one visit during NEOWISE, and then, after a 33-month gap, four more visits during the NEOWISE-Reactivation mission phase. These coadds are suitable for studying long-timescale mid-infrared variability and measuring motions to ∼1.3 mag fainter than the single-exposure detection limit. In most sky regions, our coadds span a 5.5-year time period and therefore provide a >10× enhancement in time baseline relative to that available for the AllWISE catalog’s apparent motion measurements. As such, the signature application of these new coadds is expected to be motion-based identification of relatively faint brown dwarfs, especially those cold enough to remain undetected by Gaia.
Subaru/HiCIAO HKs Imaging of LKHa 330: Multi-band Detection of the Gap and Spiral-like Structures
Authors: Uyama Taichi , Hashimoto Jun , Muto Takayuki , Akiyama Eiji , Dong Ruobing , Leon Jerome de , Sakon Itsuki , Kudo Tomoyuki , Kusakabe Nobuhiko , Kuzuhara Masayuki , Bonnefoy Mickael , Abe Lyu , Brandner Wolfgang , Brandt Timothy D. , Carson Joseph C. , Currie Thayne , Egner Sebastian , Feldt Markus , Fung Jeffrey , Goto Miwa , Grady Carol A. , Guyon Olivier , Hayano Yutaka , Hayashi Masahiko , Hayashi Saeko S. , Henning Thomas , Hodapp Klaus W. , Ishii Miki , Iye Masanori , Janson Markus , Kandori Ryo , Knapp Gillian R. , Kwon Jungmi , Matsuo Taro , Mayama Satoshi , Mcelwain Michael W. , Miyama Shoken , Morino Jun-Ichi , Moro-Martin Amaya , Nishimura Tetsuo , Pyo Tae-Soo , Serabyn Eugene , Sitko Michael L. , Suenaga Takuya , Suto Hiroshi , Suzuki Ryuji , Takahashi Yasuhiro H. , Takami Michihiro , Takato Naruhisa , Terada Hiroshi , Thalmann Christian , Turner Edwin L. , Watanabe Makoto , Wisniewski John , Yamada Toru , Yang Yi , Takami Hideki , Usuda Tomonori , Tamura Motohide
Published: July 2018

We present H- and K
s-bands observations of the LkHα 330 disk with a multi-band detection of the large gap and spiral-like structures. The morphology of the outer disk (r ∼ 0.″3) at PA = 0°–45° and PA° = 180–290° is likely density wave-induced spirals, and comparison between our observational results and simulations suggests a planet formation. We have also investigated the azimuthal profiles at the ring and the outer-disk regions as well as radial profiles in the directions of the spiral-like structures and semimajor axis. Azimuthal analysis shows a large variety in wavelength and implies that the disk has non-axisymmetric dust distributions. The radial profiles in the major-axis direction (PA = 271°) suggest that the outer region (r ≥ 0.″25) may be influenced by shadows of the inner region of the disk. The spiral-like directions (PA = 10° and 230°) show different radial profiles, which suggests that the surfaces of the spiral-like structures are highly flared and/or have different dust properties. Finally, a color map of the disk shows a lack of an outer eastern region in the H-band disk, which may hint at the presence of an inner object that casts a directional shadow onto the disk.
A Study of the Hα Variability of Be Stars
Authors: Dimitrov Dinko P. , Kjurkchieva Diana P. , Ivanov Emil I.
Published: July 2018

This paper presents the results of 4 years of high-resolution spectral observations of 69 emission-line stars, 54 of them being newly discovered sources. We classified the stars on the basis of their position in the two-color IR diagram and some additional criteria: shape and width of the Hα profile, presence of He lines, proper motion and parallax, membership to open cluster and associations. Sixty of our targets turned out to be Be stars. We also found four late giants, four pre-MS stars, and one late dwarf. The Hα emission profiles of our Be stars range from single peaked to typical shell profiles that can also be highly asymmetric or single-peaked profiles with a narrow absorption core. The emission profiles appear almost constant with time or highly variable in intensity and in their V/R ratio. The detected long-term variability of the Hα emission is important for investigating the on/off switch phenomenon of Be stars. Our study led to an increase of the number of the emission-line stars of 16 open clusters.
Jupiter’s Mesoscale Waves Observed at 5 μm by Ground-based Observations and Juno JIRAM
Authors: Fletcher Leigh N. , Melin H. , Adriani A. , Simon A. A. , Sanchez-Lavega A. , Donnelly P. T. , Antuñano A. , Orton G. S. , Hueso R. , Kraaikamp E. , Wong M. H. , Barnett M. , Moriconi M. L. , Altieri F. , Sindoni G.
Published: July 2018

We characterize the origin and evolution of a mesoscale wave pattern in Jupiter’s North Equatorial Belt (NEB), detected for the first time at 5 μm using a 2016–17 campaign of “lucky imaging” from the VISIR instrument on the Very Large Telescope and the NIRI instrument on the Gemini observatory, coupled with M-band imaging from Juno’s JIRAM instrument during the first seven Juno orbits. The wave is compact, with a 1.°1–1.°4 longitude wavelength (wavelength 1300–1600 km, wavenumber 260–330) that is stable over time, with wave crests aligned largely north–south between 14°N and 17°N (planetographic). The waves were initially identified in small (10° longitude) packets immediately west of cyclones in the NEB at 16°N but extended to span wider longitude ranges over time. The waves exhibit a 7–10 K brightness temperature amplitude on top of an ∼210 K background at 5 μm. The thermal structure of the NEB allows for both inertio-gravity waves and gravity waves. Despite detection at 5 μm, this does not necessarily imply a deep location for the waves, and an upper tropospheric aerosol layer near 400–800 mbar could feature a gravity wave pattern modulating the visible-light reflectivity and attenuating the 5-μm radiance originating from deeper levels. Strong rifting activity appears to obliterate the pattern, which can change on timescales of weeks. The NEB underwent a new expansion and contraction episode in 2016–17 with associated cyclone–anticyclone formation, which could explain why the mesoscale wave pattern was more vivid in 2017 than ever before.
Millisecond Pulsar Origin of the Galactic Center Excess and Extended Gamma-Ray Emission from Andromeda: A Closer Look
Authors: Eckner Christopher , Hou Xian , Serpico Pasquale D. , Winter Miles , Zaharijas Gabrijela , Martin Pierrick , Mauro Mattia di , Mirabal Nestor , Petrovic Jovana , Prodanovic Tijana , Vandenbroucke Justin
Published: July 2018

A new measurement of a spatially extended gamma-ray signal from the center of the Andromeda galaxy (M31) has recently been published by the Fermi-LAT collaboration, reporting that the emission broadly resembles the so-called Galactic center excess (GCE) of the Milky Way (MW). The weight of the evidence is steadily accumulating on a millisecond pulsar (MSPs) origin for the GCE. These elements prompt us to compare these observations with what is, perhaps, the simplest model for an MSP population, which is solely obtained by rescaling of the MSP luminosity function that is determined in the local MW disk via the respective stellar mass of the systems. Remarkably, we find that without free fitting parameters, this model can account for both the energetics and the morphology of the GCE within uncertainties. For M31, the estimated luminosity due to primordial MSPs is expected to only contribute about a quarter of the detected emission, although a stronger contribution cannot be excluded given the large uncertainties. If correct, the model predicts that the M31 disk emission due to MSPs is not far below the present upper bound. We also discuss additional refinements of this simple model. Using the correlation between globular cluster gamma-ray luminosity and stellar encounter rate, we gauge the dynamical MSP formation in the bulge. This component is expected to contribute to the GCE only at a level of ≲5%, it could affect the signal’s morphology. We also comment on the limitations of our model and on future perspectives for improved diagnostics.
Observational Evidence for Langmuir Wave Collapse in the Source Region of a Solar Type III Radio Burst
Authors: Thejappa G. , MacDowall R. J.
Published: July 2018

High-time-resolution in situ wave observations show that Langmuir waves associated with solar type III radio bursts often occur as coherent localized one-dimensional magnetic-field-aligned wave packets with short durations of a few milliseconds and peak intensities well above the strong turbulence thresholds. In this paper, we report observations of a wave packet obtained by the time domain sampler of the STEREO WAVES experiment, which is unique in the sense that it is the most intense wave packet ever detected in association with a solar type III radio burst, with a peak intensity E

t
 ∼ 107 mVm−1. We show that this wave packet provides evidence for (1) oscillating two-stream instability (OTSI), (2) a collapsing soliton formed as a result of OTSI, (3) the formation of a soliton–caviton pair, and (4) excitation of second and third harmonic electromagnetic waves. We also show that the peak intensity and spatial width satisfy the threshold condition for this wave packet to be the collapsing Langmuir wave packet formed as a result of nucleation processes even when δn

b
 > δn

p
, where δn

b
and δn

p
are the levels of background and ponderomotive-force-induced density fluctuations, respectively. Thus, these observations provide unambiguous evidence for the spatial collapse of Langmuir waves in the source region of a type III radio burst, and the observed spectral evidence for OTSI and the ponderomotive-force-induced density cavity strongly suggest that OTSI is mostly likely responsible for the collapse of the observed wave packet.
Deep Chandra Observations of X-Ray Point Sources in M87
Authors: Luan Luan , Jones Christine , Forman William R. , Bogdán Ákos , Andrade-Santos Felipe , Goulding Andy D. , Hickox Ryan C. , Hou Meicun , Li Zhiyuan
Published: July 2018

We present a study of X-ray source populations in M87, the cD galaxy of the Virgo cluster, using 12 archival Chandra observations with a total exposure of ∼680 ks spanning about a decade. A total of 346 point-like sources are detected down to a limiting 0.5–8 keV luminosity of 4 × 1037 erg s−1 and out to a galactocentric radius of ∼40 kpc. We cross-correlate the X-ray sources with published catalogs of globular clusters (GCs), derived from the ACS Virgo Cluster Survey and the Next Generation Virgo Cluster Survey. This results in 122 matches, making it one of the largest samples of GC-hosting X-ray sources in an external galaxy. These sources, most likely low-mass X-ray binaries (LMXBs), correspond to ∼5% of all known GCs within the Chandra field-of-view. Conversely, ∼50% of the detected X-ray sources are found in a GC. Moreover, red (metal-rich) GCs are ∼2.2 times more likely to host an X-ray source than blue (metal-poor) GCs. We also examine 76 currently known ultra-compact dwarf galaxies around M87 but find no significant X-ray counterparts. After statistically accounting for the cosmic X-ray background, we identify ∼110 field-LMXBs. The GC-LMXBs and field-LMXBs differ in their luminosity function and radial distribution, which indicates that the latter cannot be primarily originated from GCs. Using another set of deep Chandra observations toward ∼100 kpc northwest of the M87 center, we statistically constrain the abundance of field-LMXBs in the stellar halo, which is consistent with that found in the central region. We also identify 40 variable X-ray sources, among which one source is likely a black hole binary residing in a GC.
Fourier Analysis of Advection-dominated Accretion Flows
Authors: Habibi Asiyeh , Abbassi Shahram , Shadmehri Mohsen
Published: July 2018

We implement a new semi-analytical approach to investigate radially self-similar solutions for the steady-state advection-dominated accretion flows (ADAFs). We employ the usual α-prescription for the viscosity, and all components of the energy–momentum tensor are considered. In this case, in the spherical coordinate, the problem reduces to a set of eighth-order, nonlinear differential equations with respect to the latitudinal angle θ. Using the Fourier expansions for all the flow quantities, we convert the governing differential equations to a large set of nonlinear algebraic equations for the Fourier coefficients. We solve the algebraic equations via the Newton–Raphson method, and investigate the ADAF properties over a wide range of model parameters. We also show that the implemented series are truly convergent. The main advantage of our numerical method is that it does not suffer from the usual technical restrictions that may arise for solving ADAF differential equations near the polar axis. In order to check the reliability of our approach, we recover some widely studied solutions. Further, we introduce a new varying α viscosity model. New outflow and inflow solutions for ADAFs are also presented, using Fourier expansion series.
Identification of Multiple Hard X-Ray Sources in Solar Flares: A Bayesian Analysis of the 2002 February 20 Event
Authors: Sciacchitano Federica , Sorrentino Alberto , Emslie A Gordon , Massone Anna Maria , Piana Michele
Published: July 2018

The hard X-ray emission in a solar flare is typically characterized by a number of discrete sources, each with its own spectral, temporal, and spatial variability. Establishing the relationship among these sources is critical to determining the role of each in the energy release and transport processes that occur within the flare. In this paper we present a novel method to identify and characterize each source of hard X-ray emission. The method permits a quantitative determination of the most likely number of subsources present, and of the relative probabilities that the hard X-ray emission in a given subregion of the flare is represented by a complicated multiple source structure or by a simpler single source. We apply the method to a well-studied flare on 2002 February 20 in order to assess competing claims as to the number of chromospheric footpoint sources present, and hence to the complexity of the underlying magnetic geometry/topology. Contrary to previous claims of the need for multiple sources to account for the chromospheric hard X-ray emission at different locations and times, we find that a simple two-footpoint-plus-coronal-source model is the most probable explanation for the data. We also find that one of the footpoint sources moves quite rapidly throughout the event, a factor that presumably complicated previous analyses. The inferred velocity of the footpoint corresponds to a very high induced electric field, compatible with the fields in thin reconnecting current sheets.
Neutron Star Cooling with a Dynamic Stellar Structure
Authors: Dong J. M. , Wang L. J. , Zuo W.
Published: July 2018

The observations combined with theory of neutron star (NS) cooling play a crucial role in achieving the intriguing information of the stellar interior, such as the equation of state, composition, and superfluidity of dense matter. The traditional NS cooling theory is based on the assumption that the stellar structure does not change with time. The validity of such a static description has not yet been confirmed. We generalize the theory to a dynamic treatment; that is, continuous change of the NS structure (rearrangement of the stellar density distribution with the total baryon number fixed) as the decrease of temperature during the thermal evolution, is taken into account. It is found that the practical thermal energy used for the cooling is slightly lower than that estimated in a static situation, and hence the cooling of NSs is accelerated correspondingly but the effect is rather weak. Therefore, the static treatment is a good approximation in the calculations of NS cooling.
A Vacuum Ultraviolet Photoionization Study on the Formation of N-methyl Formamide (HCONHCH3) in Deep Space: A Potential Interstellar Molecule with a Peptide Bond
Authors: Frigge Robert , Zhu Cheng , Turner Andrew M. , Abplanalp Matthew J. , Bergantini Alexandre , Sun Bing-Jian , Chen Yue-Lin , Chang Agnes H. H. , Kaiser Ralf I.
Published: July 2018

As one of the simplest molecules containing a peptide bond, N-methyl formamide (HCONHCH3) represents a potential key molecule involved in the peptide bond polymerization in extraterrestrial ices. Detected tentatively toward the star-forming region Sgr B2(N2), the synthetic pathways have previously been elusive. By exploiting isomer-selective detection of the reaction products via photoionization, coupled with reflectron time-of-flight mass spectrometry (PI-ReTOF-MS), we present compelling evidence for the formation of N-methyl formamide (HCONHCH3) in astrochemically relevant ice mixtures of methylamine (CH3NH2) and carbon monoxide (CO), upon irradiation with energetic electrons as generated in the track of galactic cosmic ray particles (GCRs) penetrating interstellar ices. As one of the simplest molecules containing a peptide bond (–CO–NH–), N-methyl formamide could represent a benchmark involved in radiation-induced peptide bond polymerization in extraterrestrial ices, and thus bring us closer to revealing where in the Universe the molecular precursors linked to the origins of life might have been synthesized.
Detection of Photospheric Features in the Near-infrared Spectrum of a Class 0 Protostar
Authors: Greene Thomas P. , Gully-Santiago Michael A. , Barsony Mary
Published: July 2018

We present a near-infrared K-band R ≃ 1500 Keck spectrum of S68N, a Class 0 protostar in the Serpens molecular cloud. The spectrum shows a very red continuum, CO absorption bands, weak or nonexistent atomic metal absorptions, and H2 emission lines. The near-IR H2 emission is consistent with excitation in shocks or by X-rays but not by UV radiation. We model the absorption component as a stellar photosphere plus circumstellar continuum emission with wavelength-dependent extinction. A Markov Chain Monte Carlo analysis shows that the most likely model parameters are consistent with a low-temperature, low-gravity photosphere with significant extinction and no more than modest continuum veiling. Its T
eff ≃ 3260 K effective temperature is similar to that of older, more evolved pre-main-sequence stars, but its surface gravity log g ≃ 2.4 cm s−2 is approximately 1 dex lower. This implies that the radius of this protostar is a factor of ∼3 larger than that of 106 year old T Tauri stars. Its low veiling is consistent with a circumstellar disk having intrinsic near-IR emission that is less than or equal to that of more evolved Class I protostars. Along with the high extinction, this suggests that most of the circumstellar material is in a cold envelope, as expected for a Class 0 protostar. This is the first known detection and analysis of a Class 0 protostar absorption spectrum.
A Chandra/LETGS Survey of Main-sequence Stars
Authors: Wood Brian E. , Laming J. Martin , Warren Harry P. , Poppenhaeger Katja
Published: July 2018

We analyze the X-ray spectra of 19 main-sequence stars observed by Chandra using its LETGS configuration. Emission measure (EM) distributions are computed based on emission line measurements, an analysis that also yields evaluations of coronal abundances. The use of newer atomic physics data results in significant changes compared to past published analyses. The stellar EM distributions correlate with surface X-ray flux (F
X) in a predictable way, regardless of spectral type. Thus, we provide EM distributions as a function of F
X, which can be used to estimate the EM distribution of any main-sequence star with a measured broadband X-ray luminosity. Comparisons are made with solar EM distributions, both full-disk distributions and spatially resolved ones from active regions (ARs), flares, and the quiet Sun. For moderately active stars, the slopes and magnitudes of the EM distributions are in excellent agreement with those of solar ARs for

, suggesting that such stars have surfaces completely filled with solar-like ARs. A stellar surface covered with solar X-class flares yields a reasonable approximation for the EM distributions of the most active stars. Unlike the EM distributions, coronal abundances are strongly dependent on spectral type, and we provide relations with surface temperature for both relative and absolute abundances. Finally, the coronal abundances of the exoplanet host star τ Boo A (F7 V) are anomalous, and we propose that this is due to the presence of the exoplanet.